@ I dont think it does, because thrust comes with expelling gas, not pushing it, of course combustion will slow down as the inlets get less air but besides that, 10,000 ibs of thrust should be apples to apples at any alt
The unique thing about the 262 design is that the more you sweep the wing back the more area ruled it is, the second generation 262 was going to have the same sweep as the Sabre. That in addition with the v tail which would have greatly reduced frontal area would have made the second generation 262's an aerodynamic masterpiece.
The reduction in frontal area from sweeping the wings would be relatively minor. The vast majority of the drag reduction would be from less wave drag due to less spanwise flow. That is the real benefit of wing sweep for transonic and supersonic flight.
@@dogeness the reduction in frontal area would have been the reduction in tail surfaces from 3 to 2. The unique benefits to increasing the wing sweep in the 262 would be because it would significantly increase the benefits of "area rule". This is an important aerodynamic concept discovered in 1944 Germany.
@@shawns0762 1. Didn’t kno that about the tail surfaces. Makes sense. 2. It’s both. It’s the area ruling AND the lessening of spanwise flow. This was the reason wing sweep was done on transonic jets. Area ruling is a separate concept and was discovered afterwards. If, as you say, it is true that sweeping the wings back on the 262 makes it obey the area rule, that is purely a coincidental effect and not the original intended purpose. Many swept wing jets didn’t follow area ruling. The Sabre and Mig-15/17 didn’t. Their wing sweep was purely to decrease spanwise flow at transonic speeds.
@@dogeness Yes, increasing the wing sweep would have made it faster regardless of the increased area ruling. It was about to get afterburning turbojets as well which would have increased power by about 25%.
@@shawns0762about to get maybe isn’t the right word as they would probably not get any operational even if they had a year more before they surrendered.
It has a certain pride and elegance missing in the allied jets of the era. Maybe even more beautiful is the Arado 234 v19: ua-cam.com/video/B5665Vb8-6Q/v-deo.html
I learn more in an 30 minute episode of your channel than I did in a semester of math in college. Your presentation of what could be a mind boggling topic is very clear, concise, and well thought out. I now know that between 300 and 400 knots I can keep the G-meter at 2.8 G's and not lose any speed in my P80A Shooting Star, good to know if I get into it with a ME 262! :)
and I'll bet you the math you learned in college assumes that 1+1=2, despite that being trivially demonstrable as false. sure, 1 frog + 1 frog = 2 frogs, but 1 frog + 1 pond is not 2 of anything. and this problem occurs whenever the units on the vectors being listed are different. for instance, it shows up in fraction addition, since the denominator indicates the denomination, or unit, while the numerator indicates the number, thus you get things like 1/2 + 1/3 = 5/6, or if stripped down to bare numbers, 1+1=5. and it shows up in algebra, since 1x + 1 is neither 2x nor 2. and it shows up in unit conversions, since 1 foot + 1 yard = 48 inches, and thus 1+1=48. and in every instance of diagnosed dyscalculia that I've come across, the student actually didn't have any trouble with valid mathematics, they struggled exclusively with this shit. until I showed them the truth, and then miraculously they understood... almost as if what I'm saying here is true.
this basic point is extremely relevant to the long explanation given in the vid about how power relates to speed, because the reason people are confused there is the units. fundamentally math is about units, not numbers. hell, division is even capable of operating over bare units, and multiplication is capable of accepting either bare units or bare numbers as arguments, meaning that these operations are not even about vectors. but 'addition' and 'subtraction' require not only vectors, but specifically vectors with commensurate units... and they're the same 'operation'? the reason for that disparity is because 'addition' is not a mathematical operation at all. indeed, as I've already shown, it's quite simple to list things together that are of different units. but if you want to resolve such a list into a single vector then you need to perform unit conversions to get everything in agreement. note, however, that by definition for unit conversion to work, division must be capable of accepting bare units as its arguments. thus literally anything divided by itself is the dimensionless multiplicative identity 1. inch/inch = 1, dog/dog = 1, happiness/happiness = 1, pi/pi = 1, doesn't matter. this means that division is not actually an extension of 'subtraction' as is commonly claimed, but a different beast entirely. and it also means that the entire premise behind number theory is nonsense, as well as concepts like abelian groups.
The problem with the 262 is it wasn't a dogfighter even with newer engines installed. The weight of the turbines out on the wings drastically reduced the roll rate and is why you see no fighters these days with powerplants mounted anywhere but the fuselage as close to the centerline as possible.
I recently stumbled upon the Kommandogërat, a hydrolic-electro-mechanic control unit for the BMW 801 on the Fw190, very complex, very overengineered and very german. It looks like an interesting pre-electronic all-included computing device but can't find good info. This is the channel to ask for a video that goes deep on it. Anyway thanks for your content, Greg!
Please keep posting videos. I get more excited when I see you posted a video than anyone else. You’re a unique voice and your work is extremely informative
Don't remember this one, so I must have missed it when you first posted it. Once again, for a non-engineer audience, you managed to make most of the relevant information understandable, an accomplishment in itself (my math abilities are strictly upper-elementary school - arithmetic, fine, algebra and above, near-zero). Nicely done.
Hi Greg. I designed a little fishing aid which consisted of wings and a body/fuselage so to speak. In trying to describe some of what it does, I came up with a term 'vortectoral drag' which helped others understand what I was on about. That was 26 yrs ago. Seeing this vid has helped me understand and term what it was I was talking about. Thanks for vids Greg.
Concur. I have not taken a pilot's course since my ATP back in 1990. When I bring my old books in for one of today's cfws, he tells me that the current documents are nowhere near as good as what we had back then. I appreciate Greg going back and using tried and true proven sources
I seriously thought about fitting in the Meteor. The reason I didn't was simply due to time. I had planned a 20 min video and it sort of grew from there. I don't think the Meteor ever operated over enemy territory, of course assuming that's true, it was just a policy, so it certainly is possible that the two could have met. I might have a comparison later, it's easy to do now that the principles are knocked out in this video.
@@GregsAirplanesandAutomobiles It's very interesting to do this without the kind of nationalistic chest thumping that often goes along with this. I would like to see more of this with a focus on comparing the aircraft to "definitively prove that X aircraft is better than Y aircraft". It's far more technical than i am used to but very very good.
@@GregsAirplanesandAutomobiles The Meteor was initially relegated to anti-V-1 operations and "Red Force" training for USAAF aircrews to get experience defending against jets, but four Meteors of 616 Squadron were deployed to the continent in January 1945, shortly after the Unternehmen Bodenplatte attack by the Luftwaffe. While the pilots hoped that the Luftwaffe would send 262s to engage them, they were forbidden to fly over German-occupied territory to prevent capture of a downed aircraft. When moved forward as the front advanced, they performed recon and ground-attack duties, and wound up being painted white in an attempt to deter friendly fire; ground gunners knee-jerking that any jet was a 262 and should be shot at.
I have found that Gregg knows more about the Airplane than most people ever. I don't know how you know so much but your videos are very informative and interesting. Thank you.
Two thing about power: 1. Power (which animal lovers call horsepower) is rate of energy transfer. There is a law about energy conservation, but there is no law about power conservation. Shaft power is rate of transfer from fuel to crankstaft. Flight power is rate of energy transfer from fuel to airplane. They are not the same or generally equal. 2. As speed increases energy transfer from fuel to plane (or fuel to crankshaft or whatever) becomes more efficient. Why? Because we transfer energy by doing work. While things are constant, work = thrust X distance_over_which_we_apply_thrust When a thing goes faster distance_over_which_we_apply_thrust increases, so work increases and power increases. I like your videos. They appeal to both the WW2 buff in me and the engineer in me. Good job!
As a former fighter pilot (F-16), I can say this is pretty awesome stuff. Only thing I would say is max G limit typically is not a factor based on the pilot, but on aircraft structural limits above which you'll start stressing the airframe at least to the point of shortening its useful life, and perhaps even to warp or break the structure. Typically, post-WW II USAF jets were stressed to 7.33 Gs (though not always) and as mentioned in the video, the Navy tended to use 7.5 (F-14 was designed that way but eventually limited in practice to 6.5 to save airframe life). The F-16 was the first jet that increased that to 9Gs over the entire flight envelope (the F-15 has a weird G limit that varies within the flight envelope, initially limiting it to 7.33 until the addition of an aural G Overload Warning System which allowed 9Gs in some portions of the envelope). We see this philosophy continuing with the F-35, with the A model rated to 9Gs and the C (Navy) version to 7.5Gs only (USMC B models are 7Gs, but that's because the lift fan increases weight and reduces structural strength quite a bit). Anyway, really excellent material, keep up the good work!
Great information, thank you. The structural limits of most WW2 fighters are well above 7Gs, hence I went with 7 as I felt it's a good number for a typical pilot.
@@GregsAirplanesandAutomobiles Yes, that's right, you did well for that specific case. I just did not want viewers to think that was kind of the universal principle. In any case, that was the first of your videos I have seen, but I am going to subscribe. That was really, really well done.
@@GregsAirplanesandAutomobiles Also, regarding pilot limitations, more accurate would be to have one limit for instantaneous G and one for sustained G. I know in your examples here the sustained Gs are not all that high, so not an issue (it was a factor in the F-16 for sure!). But perhaps 7Gs is a little low for instantaneous G. It really depends on use of G suit or not (in WW II some planes had those, but most did not), and of course each individual is different (short, muscular people tend to do better). Most trained fighter pilots can probably take at least 9Gs for a few seconds, sometimes more. But anyway, minor point with no real impact on your video. Just for future reference.
@@GregsAirplanesandAutomobiles OK, I guess I need to catch up with your videos! I did not know about the 4Gs, it sounds a bit low, but then, I should not judge from the modern perspective with really nice G suits, and especially superior G-force training (the modern G-straining maneuver is critical to sustaining Gs). In any case it does not sound completely unreasonable.
Your channels is my favorite, I’m a Pilot, and a A&P and can’t tell you how much I enjoy watching your well done videos. Also agree with your ranking of the P-47. The Spitfire and Mustang are indeed elegant, but the P-47 hits my buttons in most categories. Obviously range is the Mustangs domaine. I appreciate what you do, and know your videos will be watched as long as this society survives. Best Regards
This commentary is great Greg. I often see comments / discussion saying that the P-80 was the better performing aircraft, but they often don't compare apples with apples (e.g. variants from the same years for a start). I remember Chuck Yeager stated the P-80 compared well to the Me 262 and given the variants he is likely to have flown that sounds about right. Of course its very likely that the engines in the P-80 would have been more reliable / longer lasting that the Jumo engines, simply due to the unavailability of the materials in Germany (to make reliable turbine blades) at the time. Which is just as well as the P-80 only had one engine. I have seen ME 262 aircraft in museums and they are great looking aircraft. The sweep back of the wings likely helped with max mach number, which I have heard was originally introduced to correct COG issues when the engines turned out heavier than expected.
Greg's Airplanes and Automobiles You are most welcome. I want to compliment your methodology in choosing data when there are no hard numbers. The fact that you came to the same Optimal Climb Speed for the ME-262 as the manual shows how good at that you are.
Thanks for the lesson, great to see how all the factors relate, rather than just facts and figures on aircraft performance. Helps me understand why rather than just know one airplane could out turn another.
I feel the same! I'm not a pilot or engineer or technician or anything. Just an enthusiast with a superficial knowledge of physics and engineering. But can anyone tell me if i am onto something with regards to my thoughts around induced and parasite drag? Could it be said that induced drag is caused by effects such as flow separation and drag caused by shear or interactions with the boundary layer? (unsure of exact terminology in this area) While parasite drag is the energy needed for the airplane to redirect the flow of air around itself (could this this be simplified as action=reaction between the panel being forced into the air and having to accelerate it out of the way? Inertia from the mass of the air molecules? If i am onto something here it seems to make sense to me to be the reason why parasite drag is v^2. (But that may come just from my basic physics knowledge) With induced drag, if i am thinking correctly here, it seems to make intuitive sense also that the airflow becomes more "sticky" and less likely to separate from the surface and create vortices and perhaps other effects. Would love some better educated input if anyone is able and willing. Thanks
Having just read Galland's memoir "The First and Last" I'm amazed at how close the Allies came to facing this machine in numbers up to two years earlier than they did. Amazed and relieved that it didn't happen!
The USAF museum in Dayton Ohio has a me262 and many other rare WW2 aircraft. If you find yourself near Dayton it is definitely worth your time to visit.
@@steveboz Sorry, but that about Hitler delaying the Me-262 is mostly a myth. it was a revolutionary airplane and therefore switching everything (factories, mechanics, pilots...) from piston engined aircraft to jet engined ones on a massive scale was very difficult. Add to that that Germany didn' t have the materials and that the war was already lost and you will see that it was not possible to have the Me-262 before than when it was introduced. At least to affect the war' s outcome in any significant way.
@ While that is partly true, it isn't exactly a restraint. The germans initially built the Jumo 004 with high temperature alloys and did see a somewhat reliably operating engine to up to 50 hours and more of operation. For the lower quality engines, they used some interesting tricks, like active blade cooling or aliminum coating the steel blades to improve their livespan in such a highly corrosive environment. Such engines could operate up to 25 hours until they needed a complete over hall to then work 10 to 15 hours at best until the next over hall. These engines were mostly made out of simple steel and aluminium parts and probably the most work intensive part was the check of the turbine blades by sound (inducing a vibration via violin strings and determine the quality of the blade by the frequency that has been induced). The metallurgy was the easier problem to solve, the sheer manufacturing was simply to overwhelming.
@@steveboz A couple of things to think about. One, there are two ways to turn a fighter into a bomber: one is *very* easy, and one is *very* hard. The easy way is to bolt one or more bomb racks underneath the wings and/or fuselage and carry the payload externally. This is *so* easy that AVG mechanics designed, fabricated, and installed bomb racks for their early-model P-40s in a matter of days, from scratch. In the field. In *China.* It doesn't take 2 years of redesign at the factory to bolt on a bomb rack. The hard way involves a ground-up redesign, and results in an aircraft that only vaguely resembles the original - for a great example of this process, look at how Vought derived the A-7 Corsair II from the F-8 Crusader. But the aircraft you get from this kind of process is emphatically *not* a fighter. And that brings us to Two: the first production Me262s, when they finally arrived in 1944, were fighters. Not bombers. Not even fighter-bombers. *Fighters.* Which tells us that the Me262 never was redesigned as a bomber. Galland's account is mostly bunk. Mostly, but not entirely: he got one thing right. When Me262s started rolling off the production line in 1944, Hitler was furious that they were *not* bombers. (To placate him, some later Me262s had hard points where bombs could be carried on external racks - in a lot less than two years!) The thing about memoirs - especially memoirs from high-ranking officers on the losing side of a major war - is that they tend not to be "accurate recounting of events" so much as "fables intended to whitewash the writers' own careers." In the case of post-WW2 German officers' memoirs in particular, *including Galland's,* there's a noted tendency to blame everything on the Austrian Corporal: as an amateur at warfare, and insane to boot, he made a perfect scapegoat for all of Germany's failures, misdeeds, and mistakes. (This is in no way intended to say that Hitler wasn't a nightmare walking. It just means that his interference with the military conduct of the war has been hugely overstated, and that there was plenty of blame to go around.) Memoirs should always be taken with a grain of salt the size of Everest.
First off i glad i found this channel its full of interesting information. For instance this video i watched several times as each time i gained useful knowledge.. . Thanks for the videos they will give me a better understanding of this field ..i use to work for a power generation company..i spent some time in the engineering office having the fellow in there show me on paper the math behind why thing certain things do what they do . Interesting to me . Thanks
Your dissertation on the L/D, induced drag, parasite drag and total drag reminds me of primary flight training. A good visual example of 'getting behind the power curve' can be seen in videos of the 'Sabre Dance"{F-100} and the F-16 crashes when dropping below the minimum speed on landing approach. Even an above-1-1 power to weight ratio can not assure recovery from this attitude. Love your videos, and the fine details brought forth. A refreshing break from mainstream, myth-ridden history of all these fine aircraft.
I calculated the power in KW of the Me 262 from my knowledge of physics and data from books in the early 90s and came up with a number so high I assumed I had made a mistake somewhere. Later I realised it was just due to the nature of gas turbines.
Three quarters of an hour full with interesting, comprehensible content, in a way my lecturers would be jealous of if they could fit it into one week of readings; ends the video with "thats all for this video". Thanks alot for your efforts.
That put the P51 versus ME262 Hollywood dogfights into perspective. There is just no possible way that a piston engine fighter can sustain a dogfight at reasonable speed with a Jet. On the lower speed range it appears that the Sopwith Camel can easily out-turn the P80 and ME 262. The future belongs to the Sopwith Camel!
Very interesting, as a mere life sciences grad, the non intuitive maths is very enlightening and obvious when you think about it which of course I didn’t initially 🙈 Thanks for a mathematical workout - I always learn lots from your videos Greg!
From the perspective of pure physics (or mechanics, rather), the concept of "propulsive power" goes as follows: The definition of mechanical work is W = F s (force applied over a certain distance). The definition of power is P = W/t (work done in a certain time). The definition of velocity is v = s/t (distance crossed in a certain time). Substituting the above to the equation of power, you get P = F s / t ...and since s/t equals velocity, the equation for power can be written as P = F v or, "power is the product of force and velocity". In aircraft context, the force is the thrust, and velocity is the true airspeed. In other words, the "power" is the rate at which the aircraft is doing work (moving through air) against the drag force (which at steady state flight is equal to thrust). By the way, the units in this formula should be SI-units: Newtons for force and metres per second for velocity, which will result in power in watts. Using other units requires corrective factors, as was shown in the video. All of the formulas in the video were correct, though in my opinion unnecessarily complicated because of US Navy... ;) This concept of "propulsive power" is physically very real thing, but I find it a bit of an esoteric concept. At sea level where true airspeed is practically equal to calibrated airspeed, it makes some sense and can be a reasonably useful tool for calculations. Otherwise, its usefulness is limited and in almost all situations it's more sensible to just refer to the jet engine's performance with its thrust. The thrust of a jet engine varies with airspeed, so using values from static thrust measurements doesn't necessarily give correct results at higher airspeeds. In fact, treating thrust as a constant value is almost bound to produce incorrect results, especially when you're trying to calculate sustainable top speed or maximum sustainable rate of turn (which is the same as calculating the top speed but with increased load factor). It can give you a ballpark figure for sure, but in practice you would have to look at how much actual thrust the engine is producing at a particular airspeed. If the difference between static thrust and thrust at particular airspeed is significant, then it could obviously affect the estimated sustained G-force in turn as well. A typical thrust/airspeed curve shows a high value at zero airspeed (static thrust), then it starts to decrease due to drag losses, then it starts to go back up due to ram air effect assisting in the compression of air. Some jet engines actually produce more than static thrust at very high airspeeds (though I don't think any of the WW2 era jets did that). The design of the intake and the engine itself obviously affects this a lot, and considering the P-80 and Me 262 used very different engines (centrifugal flow vs. axial flow compressors) and different intake ducting, I would expect a big difference in the thrust curves of these two aircraft. The P-80 would probably have more channel losses simply due to the length of the intake ducting and the amount of turns the airflow has to make, while the Me 262 would not be affected quite as much. On the other hand, the P-80 had the engine concealed in a fairly streamlined fuselage, while on the Me 262 the engine nacelles were out there in the wind, so the difference in parasitic drag would also make a difference.
The formulas I used are straight out of the book I referenced. You may view them as unnecessarily complicated, but I'm not sure what I can do about that. The formulas you put up are nice, and certainly correct, but I think you understand why I have to go with the official stuff in my videos, at least official in terms of pilot training. Regarding thrust varying with speed. yes, it does do that. I mentioned it, and I put up the chart from the book showing it. Since it's a small variation that we have no way to quantify in these planes, I felt it made sense to leave it out of the calculations. Frankly I'm much more worried about the possible error with the 262's clean stall speed, that's the biggest possible variable here. Thanks for your post, it's quite good.
Thanks for your description of jet power. I find it's a difficult concept to grasp, but it helps to think of it as the rate of work done to oppose drag. By the way, did you mean 'then it starts to go back *up*' in your second to last para?
@@GregsAirplanesandAutomobiles I understand the reason why you put the formulas in as they are in the source material, and why the source material has them in that form - because they want to keep using one unit for one thing (pounds for thrust and knots for airspeed in this case). Mixing and matching units is known to cause confusion, resulting in a wide range of accidents - from airliners running out of fuel (like the Gimli Glider) to Mars probes crashing due to software not doing unit conversion correctly. I didn't mean that comment as a critique of the video, but just to point out that the physics equations themselves are simpler than the equations used in the aviation textbooks and such. That is the advantage of using SI units - the equations can be more representative of the underlying physics, while the more archaic units (like knots and pounds and horsepowers and such) always require some seemingly random numbers inserted into the equation to make it spit out the numbers in the desired archaic units. Regarding the thrust variance of jet engines, I understand that sometimes there's just not enough information to work with and in those cases, using what you got is fine and usually gives results that are at least somewhat comparable to each other. The thrust variance was recognized as a possible error source, which is good. There are theoretical ways of estimating the thrust variance as a function of airspeed but without some computational fluid dynamics simulation, you'd have to do some guesswork on how the airspeed affects the flow rate through the engine - and sometimes, it's just best to minimize guesswork altogether and use the available numbers even if you know the results aren't going to be 100% accurate. In most cases the results are at least going to be comparable to each other between different aircraft. Luckily there is some information about this old tech - fragmented as it is, there is this image that looks like it comes from an original German document: i.imgur.com/qtQBoKo.jpg Unfortunately I don't know exactly what document that image comes from, so I can't tell the exact context - except that it supposedly shows the thrust curves of a Jumo 004B engine at different altitudes and airspeeds. From the document, we can see that at sea level (H=0), the static thrust is almost 900 kgf but drops quickly as airspeed increases, going as low as 680-690 kgf at airspeed of 400 km/h, and then picking up towards higher airspeeds. Since the difference can be as high as 25% of the full static thrust, I think it's fair to say it should be factored into the results, especially as the biggest thrust reduction effect happens just around the airspeeds mentioned in this video - 400 km/h is roughly 250 mph or 216 knots.
@@HerraTohtori The pic is in Russian (from their own after the war testing, may be?) and gives not only the curves of the engine thrust for different heights and speeds in SI units in the lower part, but also in the upper part the curves are the fuel consumption in kilograms per hour for a kilogram of thrust for the same heights and speeds, presumably for a single engine.
I had a unique opportunity about 12 years ago to sit in a REAL ME262. My Dad worked as a volunteer at the US Air Force Museum in Dayton, Ohio. Once a year they had an employee appreciation dinner & also opened up several planes that you can climb into. I noticed they actually had the ME262 canopy open so I climbed in, I was amazed at how few instruments were in it. That same night I sat in a P-38J Lighting, an SR71, a P-47 & the B-29 "Bocks Car" that dropped the A-bomb on Nagasaki. Quite the evening! (They don't do this anymore by the way).
I had heard the 263 was originally to have a straight plan form wing. However the Jumo engines were front heavy, so they returned the centre of balance by sweeping the wing, thus moving its CG to an ideal, just to the pilots rear as intended.
Ahhh Greg, I can see you love this stuff. Me too, now too old to remember stuff, in order. But you give me delightful insights in the stuff I have always loved. Thank you so much.
Your analysis of aircraft is absolutely amazing. Your knowledge of the subject matter and the way you present it makes your channel the best on the internet. You find in depth information on each aircraft, then explain to us amateur armchair critics what it means. Thank you for your hard work and dedication.
26:40 If you using excel or pretty much any other spreeadsheet software, you can change a setting in the graph making them interpolate any value between giving a really good estimation if intermediate values.
Hi Greg! I would love to see you do a video comparing characteristics of early Jet fighters with late "Superprop" fighters. For example, why do early jets have such horrible acceleration at low speeds?
To clear up the correct spelling of the ME262‘s name... I‘m german and very old 😂. In all older german documentaries, wochenschauen or pilot interviews it was always the „MEH zweizweiundsechzig“, means „MEH twosixtytwo“. Not „M.E. Two six two“. I also noticed that in modern english or even german documentaries the BF109 is mostly called „B.F. One O Nine“ while german pilots called it the „B.F. Hundred Nine“ or some the „MEH Hundred Nine“ or simply the „Hundred Nine“. I‘m not saying this is the official correct spelling but i noticed this has changed since the rise of the internet.
Another great book is Introduction to Flight by John Anderson. We use it in my university aerodynamics class. It’s very understandable and breaks down these similar concepts. However it costs money. Great video as usual!
Horsepower is defined as 1 hp = 550 lbs of force being applied at the rate of 1 foot per second. A knot is 1.688 feet per second so to convert from fps to knots, divide 550 by 1.688 and you get approximately 325.
Excellent, as usual, Greg - and one more demonstration of why, when I was young enough for it to be a possibility, I would have washed out of flight training before ever reaching the flight line. I understand the general ideas, but the actual math might as well be in Martian. Right after WWII, my dad went into flight testing for what was then McDonnell Aircraft, so these early jets are quite relevant to his experience. He never flew a 262, to my knowledge, but he did fly a P-80, F1H and F2H Navy fighters as they were being developed, as well as the XF-85 and XF-88 prototypes for the Air Force.
Presentation is excellent, clear, not overloading the viewers ("students") w facts all at once but building up lvl of complexity at just the right rate as well as non-biased - just factual & objective. Continue... Also, waiting for Parts #3/4 of the FW190 lectures..whenever the Muse strikes ***** 5 Stars: would watch again
@@GregsAirplanesandAutomobiles you are welcome Greg, I appreciate your deeply analytic content. I like airplanes and I am quite interested in this kind of information and I must say, congrats for the effort and RESEARCH you put on them.
Great presentations ,, I subscribed just now. One detail, however -> the sound quality of the couple vids of yours I watched... is like you are in a tin can. Not sure how other people get great sound.. just a detail. Thanks for making these presentations.
Great video Greg, it's always nice to see material from you. I'm afraid I'll have re-read it a couple more times to get my head all the way around it, but thanks for your work.
@@GregsAirplanesandAutomobiles Hi Greg, I have a question about flying and it occurs to me that you could explain it better then anyone I know. Recently I was looking at some stuffed airplanes on display and reading the explanation plaques on each. One, a U-2C, said that at it's cruising speed (?) above 70,000 ft, there was a 4 Kt difference between mach buffet and stall buffet. What does that mean? Can't quite get my head around that one either. Sounds like it was a bi+#h to fly!
Hello Greg, sorry for the late comment but I have a question : at 44:00 you are calculating the amount of G's an Me-262 can sustain, yet when I do the calculation : square root of (3940 which is the engine thrust - 1251 which is the parasitic drag):300 I get 3.03 , while in your video you say 2.88, you presumably accidenctally even mention it having 3600 pounds of thrust but even then it doesn't work, am I missing anything?
Every bit of this is fascinating. I don't know if you do requests. If you do, I would love to see a bit of a breakdown of the flight/performance characteristics of the F-104 Starfighter. How that teeny wing does was it does, is magic.
@@GregsAirplanesandAutomobiles Thanks for responding and thanks for the link. I kinda figured but I thought I'd ask. You're a busy guy. I can't imagine the work that goes into your analysis. I'm not sure how you find the time to sleep, much less start any new projects. Have a good day.
Thanks for watching. I do try and not only list sources, but put the actual pages up (they are not copyrighted) so you can pause if needed and read it for yourself.
@@GregsAirplanesandAutomobiles Well, yes. I could... But the entire bummer of ad hoc 135 is what convinced me to retire in the first place. So I'm thinking that maybe a better plan is to rent some hanger space somewhere and start building BD-5's or whatever.
Just want to say that if you do velocity in m/s, and thrust in newtons, you get kW without needing a correction factor. Why I like working in SI units.
That crap is too easy and it will rot your brain. That's why the Americans never complain if the units are in Metric, because they can understand both.
No no no. 144/48 = 3. "In aerodynamics, it's always a square or a square root". It should take you 48/(1/sqrt2) minutes to watch the video, the first time. If you have enough excess power to sustain that rate. Personally, I got GLOC a few times in the video and had to pause it.
@@GregsAirplanesandAutomobiles I shoulda said Greg, great video. I was an aeronautical engineering undergrad and this took me straight back to Mechanics of Flight lectures, and dreams of slipping the surly bonds of earth and dancing the skies on laughter-silvered wings. Happy days, man: great video.
I believe the 262 was designed to cause allied pilots to poop their breeches. When asked about the 262 (which he loved) Winkle Brown said, quite enthusiastically, "power, power POWER".
Unless I missed it the numbers used in this video were for sea level performance, correct? How did the effects of altitude change the graphs? I am assuming that the changes in power output of the two A/C engines is not identical at altitudes and that an A/C with thrust advantage at 15,000 FT may not have that same advantage at 32,000 FT. Also because indicated airspeed and true airspeed diverge in increasing amounts as altitude increases and indicated airspeed is what determines aerodynamic performance won't the A/C with the lower stall speed gain relative advantages at higher altitudes? I have read that the ME262 performance decreased substantially above 24,000 FT. Just how did the effects of altitude differ for these aircraft?
Hi Keith, it was in the video, but easy to miss. All the numbers I used are at sea level and airspeeds are in CAS MPH. The primary purpose of this video was to clairfy some principles which will factor into further comparisons in later videos. To keep everything simple (relatively simple), I kept everything down at sea level specifically so I wouldn't have to cover power decreasing with altitude, and the True vs. Calibrated, vs. Indicated airspeed issues. In other words, as I stated, this wasn't intended as a total comparison of the two planes, but rather an explanation of principles, in which we gathered some comparative data. Now, in aerodynamic terms, yes the plane with the lower stall speed will gain advantage with altitude, and both jets will loose power up high. None of that is covered in this video. I am planning on covering that when I get to the TA152.
@@GregsAirplanesandAutomobiles Thanks for your reply. I am unsure of the differences on the compressor stage performance in the engines in the P-80 and the ME262 but I was surprised in altitude performance of the ME262. Was wondering how the P-80 did at higher altitude Vs. 262. Interesting to see how you constructed the performance profiles of these aircraft. I would add, though that you would only see these numbers in a wind tunnel environment. TA152 should be interesting VS P-47M with late engine MP and RPM specs as related in Pratt Whitney tech notices. Looking forward to it!
One useful thing to realize is that power, horsepower is just an abstract construct used to help us with performance calculations and comparisons. It's not something we can measure directly, there's no horsepower-o-meter. What we can measure are force (thrust), torque, speed, and convert them to power using mathematical formulas. So instead of thinking too much about abstract propulsive horsepower doubling with speed (sorcery!), it's easier to think about the measurable force applied on an airframe, which is engine thrust. Jet engine thrust does not drop down with speed, which is a huge advantage over prop driven aircraft, because propeller thrust drops down considerably as the speed increases. And falls of a cliff when the propeller goes supersonic. That's the reason jet vs. prop power diagrams look like they do on the video. On the other hand, propellers generate a lot of thrust at low speeds, that's why turboprops are still a thing.
@@GregsAirplanesandAutomobiles Thanks. I'm not trying to correct the video by any means, I just thought I'd write what helped me grasp this topic some time ago.
For impatient - formula is @ 18:04 :) Very informative video btw, you could mention that power loading for turbojet engine is different than for turboprop or turbofan of the same thrust, which have lower disc loading - and thus need less power (hp) for the same thrust as turbojet.
Thanks, I should add that time stamp to the description. Probably one for when the video gets to the comparative drag data as well. I understand that the entire video is a bit much for some people. It's not aimed at the masses. I thought about power loading issues, but the video just came out way too long as it was, I was aiming for 20mins.
Technically you can also calculate horsepower for a jet engine as thrust power, which is different (and much less useful) than propulsive power. In this case, you use the velocity of the exhaust gas in place of the velocity of the aircraft. Unfortunately it's hard to find information as to the exhaust velocity for the 004. However, as best I can tell, it had a max exhaust temperature somewhere in the region of 670C. Using kinetic gas theory, that translates to about 750m/s, or mach 2.2 That produces about 3.3MW per engine, or about 4400hp, for a total of ~8800. Of course this figure is mostly only for academic interest, it's not very useful for flight performance. About the only real world application it has is determining how much damage a jet engine will do to something directly behind it.
Hi again Greg. Here it goes. I apologise for the length but please read it through before disregarding any point as they are all related. 1- At around 6:15 you say the green arrow is the resultant of the force generated by the wing. I agree, it is the vector addition of lift and total drag. Then you say there is a rearwards component of this force, the red arrow, correct. But then at around 6:30 you say "this rearward component of lift is the induced drag". The statement is correct, the induced drag is the rearward component of lift, but this red arrow is not the rearward component of lift. As you have already said seconds before, the lift is the vertical black arrow, hence it can't have a rearward component. The red arrow is the rearward componet of the total resultant force on the wing, the green arrow, and hence it is the total drag. Please bear with me until the end of the post, because I'll try to explain how the lift is tilted rearwards in a finite wing and thus generates the induced drag, which it really is the backwards component of lift, as you said, but not in the way you are showing in this diagram. 2- At 6:43 you show a quote from AFNA that is, of course, correct. But please note that it says explicitly "finite wing" not just "wing". Why would they bother to state this considering that all real wings on all real airplanes are finite and no infinite wing exits or can exist? It seems unnecesary to say it, doesn't it? The answer is because the wings being finite (i.e. they have wingtips) is the ultimate cause of the induced drag. Please, again, bear with me until the end of the explanation. 3- Your explanation starting around 06:15 disregards this and it could be applied exactly as it is to explain induced drag for an hypothetical infinite span wing (i.e. a wing without wingtips), but infinite wings don´t have induced drag as the quote from AFNA of point 2 above implies when it explicitly says "finite wing", when it would seem unnecesaty to state it. 4- How then is the induced drag created if the lift vector is always perpendicular to the airflow as you shown with the black arrow at around 6:15? Because the wing being finite, and this is the key point, there is a circulation of air from the surface below the wing to the top of the wing around the wingtips due to the pressure difference between both surfaces. This circulation creates a spanwise flow of air (from the wingtip to the wing root on the upper surface and from the root to the wingtip in the lower one) and the wingtip vortices. All this tilts downwards the airflow the wing encounters locally (i. e. the "downwash"). If the airflow is tilted downwards then the lift vector is tilted backwards, as it is perpendicular to the airflow by definition, hence now it has a component in the horizontal direction and pointed backwards: the induced drag, exactly as you said and quoted from AFTA from 6:42 to 6:45 but didn't quite draw correctly in the diagram. If you had considered this you'd have drawn the black arrow slightly tilted to the rear and explained why in a similar way to what I just wrote here. 5- Further, albeit indirect, proof that the induced drag is created by the wingtip circulation flow, as indicated in point 4, is the fact that some airplanes have winglets in the wingtips. Their purpose is to reduce this flow which in turn reduces the induced drag. Please consider that this is not the explanation of a random guy in youtube. I just tried to summarize the best I could and without the advantage of diagrams the explanation given by John Anderson, who is the Curator of Aerodynamics of the National Air and Space Museum Smithsonian Institution and Professor Emeritus of the University of Maryland, in chapter 5 of his book "Fundamentals of aerodynamics" 6th edition published in 2017. I am not asking you to accept my word, I am just asking you to check the book for yourself. How difficult can this be for someone that has been searching in 70 year old documents to get data for a comparison between the P-80 and the Me-262? I even offered to send you pictures of the relevant pages. It is not in contradiction with your quote from AFNA, they agree. It is your diagram that fails to acknowledge the source of the induced drag, the downwash created by the vortices created by the flow around the wingtips. So, I think I tried to the best of my ability, now I leave it in your hands. I can´t do anything more without repeating myself over and over. Just one more thing. To give credit where is due I quote some paragraphs from the book that are much better than anything I could possibly write: "In chapter 4 we discussed the properties of airfoils, which are the same as the properties of a wing of infinite span; indeed airfoil data are frequently denoted as `infinite wing´ data. However, all real airplanes have wings of finite span, and the purpose of the present chapter is to apply our knowledge of airfoil properties to the analysis of such finite wings." "Question: Why are the aerodynamic characteristics of a finite wing any different from the properties of its airfoil sections? Indeed, an airfoil is simply a section of a wing, and at first thought, you might expect the wing to behave exactly the same as the airfoil. However, as studied in Chapter 4, the flow over an airfoil is two-dimensional. In contrast, a finite wing is a three-dimensional body, and consequently the flow over the finite wing is three-dimensional; that is, there is a component of flow in the spanwise direction." "The tendency for the flow to `leak´ around the wing tips has another important effect on the aerodynamics of the wing. This flow establishes a circulatory motion that trails downstream of the wing; that is, a trailing vortex is created at each wing tip" "These wing tip vortices downstream of the wing induce a small downward component of air velocity in the neighborhood of the wing itself [...]. This downward component is called downwash [...]. In turn, the downwash combines with the freestream velocity to produce a local relative wind which is canted downward in the vicinity of each airfoil section of the wing." "The presence of downwash, and its effect on inclining the local relative wind in the downward direction, has two important effects on the local airfoil sections, as follows: 1- [...] Although the wind is at a geometric angle of attack, the local airfoil section is seeing a smaller angle, namely, the effective angle of attack. [...] 2- The local lift vector is aligned perpendicular to the local relative wind, and hence is inclined behind the vertical angle [...]. Consequently, there is a component of the local lift vector in the direction of the airflow; that is, there is a drag created by the presence of downwash. This drag is defined as induced drag."
I read all of this, but I'll have to respond in pieces due to my other obligations. I'll take point #1 first. That diagram is something I made in Paint, it's intended to give an overall picture. I clearly said in regards to this diagram that it's a bit simplified. Still, let's go over what I said. I said "the force being generated by the wing is represented by the green arrows here, the lift is the vertical component, however there is a rearward component". Now I am clearly talking about the green arrow there, which you apparently didn't hear. Now in the next sentence I do refer to that as the rearward component of lift. I did that to be in harmony with the statement from AFNA which I put on screen seconds later. As for your statement that the red arrow is the total drag, that might be true in another context, but the context of the discussion at this point was induced drag, we were not talking about other types of drag.
@@GregsAirplanesandAutomobiles Greg, I am sorry but if the green arrow is the total resultant force on the wing as you say in the video, the red arrow (its horizontal component) can not be the induced drag. As you yourself said the induced drag is the horizontal component of lift, not the horizontal component of the total resultant force on the wing. Now, if you say that the green arrow is the lift tilted backwards by the downwash, I agree, the red arrow is the horizontal component of lift and therefore the induced drag..
No, I didn't say anything about downwash. I am also not saying that the green arrow is the "lift tilted backwards by the wing". Lift is clearly defined as being perpendicular to the relative wind. Lift being tilted backwards is not a part of the definition. That's the reason I added the green arrows.
Pretty darned interesting. The concept of a piston engine not rotating a crankshaft at 20:34 might be able to use the average piston speed as your linear motion rather than the rotation of the crankshaft. What happens when you apply the same logic to a piston engine/propeller driven aircraft and determine it's relative propulsive horsepower, since you show a beautiful Packard built Merlin in your video, use a P-51 and a Spitfire in their top of the line designs for a similar comparison as the 262 vs the P-80? I see there's one for the P-51 vs the (which version, BF or ME?) 109 so half the comparison is already done. It would be very interesting to see how the numbers compare given two airplanes that are so dissimilar and yet used the same engine. Just for giggles and fun how about a later model P-47. Discussing the F-14 reminds me of the demonstration they used to do at the Point Mugu Naval Air Station "Space Fair". The F-14 would do a 360 degree turn while keeping between the runway and the perimeter of the base. It was both scary and very very impressive both of the plane's capability and the pilot's ability to fly in such a edge of the envelope maneuver. He would be in a near 90 degree bank and full afterburner and you could see the pilot changing the bank angle constantly to avoid going over the edge. He did this only 150 or so feet above ground level, if that. I doubt he would have survived had the airplane stalled. Personally I think the navy gave up a huge advantage in air superiority when they retired the F-14. Yep. Very interesting video. Otherwise I wouldn't have such a large comment. And near the end you did mention propeller driven aicraft but not a comparison of the 2 different planes with the same engine that I suggested. I won't kid myself that I could do it myself because I can't. I also won't kill myself is you never do it. But I do intend to watch your other videos. Thanks Chris
Hi Chris, I saw the Blue Angels perform in F4 Phantoms at Point Magu when I was very young. I just flew into Point Magu myself a couple weeks ago and talked to some Navy pilots. It really brought back memories.
hmm... since you mentioned later upgrades, could we consider the newer Me 262 with GE engines in comparison to upgraded P-80's and late war meteors too? would be quite interesting to compare the newer frame (altho not as fast on the deck for safety reasons...).
For the 262, are there numbers for lift, drag, Vx and Vy from the modern replicas that are flying? You could then adjust for the engine difference between original and replica.
it would be really interesting to compare the ME262 to the Gloster Meteor as they had a real chance of fighting each other in 1944-1945. The Meteor had been held back in UK to take out V1s and also the British didn't want to lose one over enemy lines. I believe they would've been a closer match than most people think.
Most low altitude max climb rates in a jet are accomplished at a constant indicated or calibrated airspeeds. This requires a small amount of acceleration to maintain, while small, is not zero and is noticeable.
Just thinking. The turbine section drives a shaft that, in turn, drives the compressor section. There is some measurable hp there. The accelerated exhaust being the source of propulsion that is hard to calculate into hp.
My flight instructor told me one pound of thrust equals one horsepower at 375 Mph. I find that useful to do a quick calculation of power because I have difficulty conceptualising "thrust" compared to HP.
Think about it this way: A piston engine, propeller driven plane uses the propeller to convert the engine's horsepower into thrust from the burning fuel. However, the turbojet engine uses the burning fuel directly to produce thrust. Either way, it's the thrust produced by the engine that is acting against drag, not the engine's "horsepower".
Glide distance (glide slope) will vary with weight because as you increase wing loading you shift the induced drag curve to the right and the lowest drag value will also increase.
Aerodynamics for Naval Aviators disagrees with you, specifically pages 32 and 33 if you want to look it up. Here is the quote: "An unbelievable feature of gliding performance is the effect of airplane gross weight. Since the maximum lift-drag ratio of a given airplane is an intrinsic property of the aerodynamic configuration, gross weight will not affect the gliding performance." You can go to the actual source for more info on this if desired.
That's correct, at high speeds glide distance decreases because you are getting too far from the optimal speed. Best glide speed in an airliner varies a lot with weight, but the glide ratio stays the same. I'll use a Boeing 767 since that's what I fly. Best glide speed in this plane happens at Vref +80 which is the minimum maneuvering speed with the flaps up. At typical weights this is about 230 knots, but at or near max weight it's around 254 knots. The speed can actually be pulled up on the CDU. Actually, you pull up the best angle of climb speed on the display, but that coincides with best glide speed in a jet airplane. (source AFNA page 32).
No one else on UA-cam is putting out this kind of content, with this level of quality. Keep up the great work Greg!
Thanks, and I understand and love your user name.
@@GregsAirplanesandAutomobiles Well, I'm glad neither of us will have to answer to the Coca-Cola company!
LOL
@ I dont think it does, because thrust comes with expelling gas, not pushing it, of course combustion will slow down as the inlets get less air but besides that, 10,000 ibs of thrust should be apples to apples at any alt
@@cerdon4076 But would the surrounding air density effect how the gas is expelled?
Finally... Some one is doing real comparison of WWII Jets! Great job mate!
The unique thing about the 262 design is that the more you sweep the wing back the more area ruled it is, the second generation 262 was going to have the same sweep as the Sabre. That in addition with the v tail which would have greatly reduced frontal area would have made the second generation 262's an aerodynamic masterpiece.
The reduction in frontal area from sweeping the wings would be relatively minor. The vast majority of the drag reduction would be from less wave drag due to less spanwise flow. That is the real benefit of wing sweep for transonic and supersonic flight.
@@dogeness the reduction in frontal area would have been the reduction in tail surfaces from 3 to 2. The unique benefits to increasing the wing sweep in the 262 would be because it would significantly increase the benefits of "area rule". This is an important aerodynamic concept discovered in 1944 Germany.
@@shawns0762 1. Didn’t kno that about the tail surfaces. Makes sense.
2. It’s both. It’s the area ruling AND the lessening of spanwise flow. This was the reason wing sweep was done on transonic jets. Area ruling is a separate concept and was discovered afterwards. If, as you say, it is true that sweeping the wings back on the 262 makes it obey the area rule, that is purely a coincidental effect and not the original intended purpose. Many swept wing jets didn’t follow area ruling. The Sabre and Mig-15/17 didn’t. Their wing sweep was purely to decrease spanwise flow at transonic speeds.
@@dogeness Yes, increasing the wing sweep would have made it faster regardless of the increased area ruling. It was about to get afterburning turbojets as well which would have increased power by about 25%.
@@shawns0762about to get maybe isn’t the right word as they would probably not get any operational even if they had a year more before they surrendered.
The ME 262 is just a beautiful aircraft.
It sure is!
It has a certain pride and elegance missing in the allied jets of the era. Maybe even more beautiful is the Arado 234 v19: ua-cam.com/video/B5665Vb8-6Q/v-deo.html
It looks like an ugly pipe gun.
@@coryfice1881 no it doesn't
@@vadimpm1290 yes it does.
I learn more in an 30 minute episode of your channel than I did in a semester of math in college. Your presentation of what could be a mind boggling topic is very clear, concise, and well thought out. I now know that between 300 and 400 knots I can keep the G-meter at 2.8 G's and not lose any speed in my P80A Shooting Star, good to know if I get into it with a ME 262! :)
and I'll bet you the math you learned in college assumes that 1+1=2, despite that being trivially demonstrable as false.
sure, 1 frog + 1 frog = 2 frogs, but 1 frog + 1 pond is not 2 of anything. and this problem occurs whenever the units on the vectors being listed are different. for instance, it shows up in fraction addition, since the denominator indicates the denomination, or unit, while the numerator indicates the number, thus you get things like 1/2 + 1/3 = 5/6, or if stripped down to bare numbers, 1+1=5. and it shows up in algebra, since 1x + 1 is neither 2x nor 2. and it shows up in unit conversions, since 1 foot + 1 yard = 48 inches, and thus 1+1=48.
and in every instance of diagnosed dyscalculia that I've come across, the student actually didn't have any trouble with valid mathematics, they struggled exclusively with this shit. until I showed them the truth, and then miraculously they understood... almost as if what I'm saying here is true.
this basic point is extremely relevant to the long explanation given in the vid about how power relates to speed, because the reason people are confused there is the units. fundamentally math is about units, not numbers. hell, division is even capable of operating over bare units, and multiplication is capable of accepting either bare units or bare numbers as arguments, meaning that these operations are not even about vectors.
but 'addition' and 'subtraction' require not only vectors, but specifically vectors with commensurate units... and they're the same 'operation'? the reason for that disparity is because 'addition' is not a mathematical operation at all. indeed, as I've already shown, it's quite simple to list things together that are of different units. but if you want to resolve such a list into a single vector then you need to perform unit conversions to get everything in agreement.
note, however, that by definition for unit conversion to work, division must be capable of accepting bare units as its arguments. thus literally anything divided by itself is the dimensionless multiplicative identity 1. inch/inch = 1, dog/dog = 1, happiness/happiness = 1, pi/pi = 1, doesn't matter. this means that division is not actually an extension of 'subtraction' as is commonly claimed, but a different beast entirely. and it also means that the entire premise behind number theory is nonsense, as well as concepts like abelian groups.
Those darned ME-262s will get ya on the daily commute if you aren't careful!
@@sumdumbmick Your two comments took me in for a spin, but in the end you make a valid point.
The problem with the 262 is it wasn't a dogfighter even with newer engines installed. The weight of the turbines out on the wings drastically reduced the roll rate and is why you see no fighters these days with powerplants mounted anywhere but the fuselage as close to the centerline as possible.
I have been curious about p80 and me262 performance for years. Your research and presentation is top notch. Well done Sir!
>log in to youtube to play some music to work to
>new Greg video
>shut office door and settle in for 48 minutes of putting off work
Good stuff Greg, and I'll have a look at Aerodynamics for Naval Aviators. Thanks for the recommendation.
Thanks Central.
This is a gem of a channel, thanks for so much thoughtful and high effort content!
Messerschmitt Me 262 and P-80 Thrust, Drag, and Horsepower - I haven't been so excited in weeks. Thank you!
c0^id has worn you thin. You need to get out more.
I recently stumbled upon the Kommandogërat, a hydrolic-electro-mechanic control unit for the BMW 801 on the Fw190, very complex, very overengineered and very german. It looks like an interesting pre-electronic all-included computing device but can't find good info. This is the channel to ask for a video that goes deep on it. Anyway thanks for your content, Greg!
I'll cover it at some point.
Please keep posting videos. I get more excited when I see you posted a video than anyone else. You’re a unique voice and your work is extremely informative
Don't remember this one, so I must have missed it when you first posted it. Once again, for a non-engineer audience, you managed to make most of the relevant information understandable, an accomplishment in itself (my math abilities are strictly upper-elementary school - arithmetic, fine, algebra and above, near-zero). Nicely done.
Hi Greg. I designed a little fishing aid which consisted of wings and a body/fuselage so to speak. In trying to describe some of what it does, I came up with a term 'vortectoral drag' which helped others understand what I was on about. That was 26 yrs ago. Seeing this vid has helped me understand and term what it was I was talking about. Thanks for vids Greg.
Never thought anybody would ever put this excellent presentation together. Thank you. Look forward to more !
Take heed guys. This is a free performance course. Even today's pilots can benefit from this. Thanks Capt very well done.
Concur. I have not taken a pilot's course since my ATP back in 1990. When I bring my old books in for one of today's cfws, he tells me that the current documents are nowhere near as good as what we had back then. I appreciate Greg going back and using tried and true proven sources
With over 3 decades in aviation I'm still learning everyday Thanks to people like you! Great content!!!
Amazing work! Now we need a similar analysis for the 262 and the (early) Gloster Meteor, as these were operational and could have met in combat.
I seriously thought about fitting in the Meteor. The reason I didn't was simply due to time. I had planned a 20 min video and it sort of grew from there. I don't think the Meteor ever operated over enemy territory, of course assuming that's true, it was just a policy, so it certainly is possible that the two could have met. I might have a comparison later, it's easy to do now that the principles are knocked out in this video.
@@GregsAirplanesandAutomobiles It's very interesting to do this without the kind of nationalistic chest thumping that often goes along with this. I would like to see more of this with a focus on comparing the aircraft to "definitively prove that X aircraft is better than Y aircraft". It's far more technical than i am used to but very very good.
@@GregsAirplanesandAutomobiles The Meteor was initially relegated to anti-V-1 operations and "Red Force" training for USAAF aircrews to get experience defending against jets, but four Meteors of 616 Squadron were deployed to the continent in January 1945, shortly after the Unternehmen Bodenplatte attack by the Luftwaffe. While the pilots hoped that the Luftwaffe would send 262s to engage them, they were forbidden to fly over German-occupied territory to prevent capture of a downed aircraft. When moved forward as the front advanced, they performed recon and ground-attack duties, and wound up being painted white in an attempt to deter friendly fire; ground gunners knee-jerking that any jet was a 262 and should be shot at.
A He162 shoot down a gloster during ww2 first jet vs jet combat
@@YUSKHAN : please state a source as I think that is debunkable information
I have found that Gregg knows more about the Airplane than most people ever. I don't know how you know so much but your videos are very informative and interesting. Thank you.
Two thing about power:
1. Power (which animal lovers call horsepower) is rate of energy transfer.
There is a law about energy conservation, but there is no law about power conservation.
Shaft power is rate of transfer from fuel to crankstaft. Flight power is
rate of energy transfer from fuel to airplane. They are not the same or generally equal.
2. As speed increases energy transfer from fuel to plane (or fuel to crankshaft
or whatever) becomes more efficient. Why? Because we transfer energy by doing
work. While things are constant,
work = thrust X distance_over_which_we_apply_thrust
When a thing goes faster distance_over_which_we_apply_thrust increases, so work
increases and power increases.
I like your videos. They appeal to both the WW2 buff in me and the engineer in me. Good job!
Wow, great video...so much great information. Enjoyed it a lot. Always happy to see a new video from you. Wow!
Thanks Carl. I'm glad I made this one, as it takes care of a lot of principles I'll need to reference in the future.
As a former fighter pilot (F-16), I can say this is pretty awesome stuff. Only thing I would say is max G limit typically is not a factor based on the pilot, but on aircraft structural limits above which you'll start stressing the airframe at least to the point of shortening its useful life, and perhaps even to warp or break the structure. Typically, post-WW II USAF jets were stressed to 7.33 Gs (though not always) and as mentioned in the video, the Navy tended to use 7.5 (F-14 was designed that way but eventually limited in practice to 6.5 to save airframe life). The F-16 was the first jet that increased that to 9Gs over the entire flight envelope (the F-15 has a weird G limit that varies within the flight envelope, initially limiting it to 7.33 until the addition of an aural G Overload Warning System which allowed 9Gs in some portions of the envelope). We see this philosophy continuing with the F-35, with the A model rated to 9Gs and the C (Navy) version to 7.5Gs only (USMC B models are 7Gs, but that's because the lift fan increases weight and reduces structural strength quite a bit). Anyway, really excellent material, keep up the good work!
Great information, thank you. The structural limits of most WW2 fighters are well above 7Gs, hence I went with 7 as I felt it's a good number for a typical pilot.
@@GregsAirplanesandAutomobiles Yes, that's right, you did well for that specific case. I just did not want viewers to think that was kind of the universal principle. In any case, that was the first of your videos I have seen, but I am going to subscribe. That was really, really well done.
@@GregsAirplanesandAutomobiles Also, regarding pilot limitations, more accurate would be to have one limit for instantaneous G and one for sustained G. I know in your examples here the sustained Gs are not all that high, so not an issue (it was a factor in the F-16 for sure!). But perhaps 7Gs is a little low for instantaneous G. It really depends on use of G suit or not (in WW II some planes had those, but most did not), and of course each individual is different (short, muscular people tend to do better). Most trained fighter pilots can probably take at least 9Gs for a few seconds, sometimes more. But anyway, minor point with no real impact on your video. Just for future reference.
I talk about that a bit in another video. During WW2 the USAAF considered 4Gs as the maximum sustainable. Thank you for subscribing, I appreciate it.
@@GregsAirplanesandAutomobiles OK, I guess I need to catch up with your videos! I did not know about the 4Gs, it sounds a bit low, but then, I should not judge from the modern perspective with really nice G suits, and especially superior G-force training (the modern G-straining maneuver is critical to sustaining Gs). In any case it does not sound completely unreasonable.
Your channels is my favorite, I’m a Pilot, and a A&P and can’t tell you how much I enjoy watching your well done videos. Also agree with your ranking of the P-47. The Spitfire and Mustang are indeed elegant, but the P-47 hits my buttons in most categories. Obviously range is the Mustangs domaine. I appreciate what you do, and know your videos will be watched as long as this society survives. Best Regards
You do a phenomenally good job of teaching flight principles and improving the understanding of competitive fighting envelopes in combat aircraft.
Thank you. I am trying here.
This commentary is great Greg. I often see comments / discussion saying that the P-80 was the better performing aircraft, but they often don't compare apples with apples (e.g. variants from the same years for a start). I remember Chuck Yeager stated the P-80 compared well to the Me 262 and given the variants he is likely to have flown that sounds about right.
Of course its very likely that the engines in the P-80 would have been more reliable / longer lasting that the Jumo engines, simply due to the unavailability of the materials in Germany (to make reliable turbine blades) at the time. Which is just as well as the P-80 only had one engine.
I have seen ME 262 aircraft in museums and they are great looking aircraft. The sweep back of the wings likely helped with max mach number, which I have heard was originally introduced to correct COG issues when the engines turned out heavier than expected.
I really enjoyed this video, right up until my head exploded.
Haha, me too.
Impressive reconstructive effort. There isn’t a whole lot of data on these planes, and it’s really awesome to see the effort that you put into this.
Thank you.
Greg's Airplanes and Automobiles You are most welcome. I want to compliment your methodology in choosing data when there are no hard numbers. The fact that you came to the same Optimal Climb Speed for the ME-262 as the manual shows how good at that you are.
Thanks for the lesson, great to see how all the factors relate, rather than just facts and figures on aircraft performance. Helps me understand why rather than just know one airplane could out turn another.
This channel is where the term "my brain is full" applies best. Thanks for an excellent video that makes me think.
I feel the same! I'm not a pilot or engineer or technician or anything. Just an enthusiast with a superficial knowledge of physics and engineering. But can anyone tell me if i am onto something with regards to my thoughts around induced and parasite drag?
Could it be said that induced drag is caused by effects such as flow separation and drag caused by shear or interactions with the boundary layer? (unsure of exact terminology in this area)
While parasite drag is the energy needed for the airplane to redirect the flow of air around itself (could this this be simplified as action=reaction between the panel being forced into the air and having to accelerate it out of the way? Inertia from the mass of the air molecules?
If i am onto something here it seems to make sense to me to be the reason why parasite drag is v^2. (But that may come just from my basic physics knowledge)
With induced drag, if i am thinking correctly here, it seems to make intuitive sense also that the airflow becomes more "sticky" and less likely to separate from the surface and create vortices and perhaps other effects.
Would love some better educated input if anyone is able and willing.
Thanks
Having just read Galland's memoir "The First and Last" I'm amazed at how close the Allies came to facing this machine in numbers up to two years earlier than they did. Amazed and relieved that it didn't happen!
I need to re-read that book, I last read it about 30 years ago.
The USAF museum in Dayton Ohio has a me262 and many other rare WW2 aircraft. If you find yourself near Dayton it is definitely worth your time to visit.
@@steveboz Sorry, but that about Hitler delaying the Me-262 is mostly a myth. it was a revolutionary airplane and therefore switching everything (factories, mechanics, pilots...) from piston engined aircraft to jet engined ones on a massive scale was very difficult. Add to that that Germany didn' t have the materials and that the war was already lost and you will see that it was not possible to have the Me-262 before than when it was introduced. At least to affect the war' s outcome in any significant way.
@
While that is partly true, it isn't exactly a restraint. The germans initially built the Jumo 004 with high temperature alloys and did see a somewhat reliably operating engine to up to 50 hours and more of operation. For the lower quality engines, they used some interesting tricks, like active blade cooling or aliminum coating the steel blades to improve their livespan in such a highly corrosive environment. Such engines could operate up to 25 hours until they needed a complete over hall to then work 10 to 15 hours at best until the next over hall. These engines were mostly made out of simple steel and aluminium parts and probably the most work intensive part was the check of the turbine blades by sound (inducing a vibration via violin strings and determine the quality of the blade by the frequency that has been induced).
The metallurgy was the easier problem to solve, the sheer manufacturing was simply to overwhelming.
@@steveboz A couple of things to think about. One, there are two ways to turn a fighter into a bomber: one is *very* easy, and one is *very* hard. The easy way is to bolt one or more bomb racks underneath the wings and/or fuselage and carry the payload externally. This is *so* easy that AVG mechanics designed, fabricated, and installed bomb racks for their early-model P-40s in a matter of days, from scratch. In the field. In *China.* It doesn't take 2 years of redesign at the factory to bolt on a bomb rack.
The hard way involves a ground-up redesign, and results in an aircraft that only vaguely resembles the original - for a great example of this process, look at how Vought derived the A-7 Corsair II from the F-8 Crusader. But the aircraft you get from this kind of process is emphatically *not* a fighter.
And that brings us to Two: the first production Me262s, when they finally arrived in 1944, were fighters. Not bombers. Not even fighter-bombers. *Fighters.* Which tells us that the Me262 never was redesigned as a bomber. Galland's account is mostly bunk.
Mostly, but not entirely: he got one thing right. When Me262s started rolling off the production line in 1944, Hitler was furious that they were *not* bombers. (To placate him, some later Me262s had hard points where bombs could be carried on external racks - in a lot less than two years!)
The thing about memoirs - especially memoirs from high-ranking officers on the losing side of a major war - is that they tend not to be "accurate recounting of events" so much as "fables intended to whitewash the writers' own careers." In the case of post-WW2 German officers' memoirs in particular, *including Galland's,* there's a noted tendency to blame everything on the Austrian Corporal: as an amateur at warfare, and insane to boot, he made a perfect scapegoat for all of Germany's failures, misdeeds, and mistakes. (This is in no way intended to say that Hitler wasn't a nightmare walking. It just means that his interference with the military conduct of the war has been hugely overstated, and that there was plenty of blame to go around.) Memoirs should always be taken with a grain of salt the size of Everest.
Not only a great video but some good and intelligent comments. Also very nice that Greg addresses many of the comments .
Thanks George.
First off i glad i found this channel its full of interesting information. For instance this video i watched several times as each time i gained useful knowledge.. . Thanks for the videos they will give me a better understanding of this field ..i use to work for a power generation company..i spent some time in the engineering office having the fellow in there show me on paper the math behind why thing certain things do what they do . Interesting to me . Thanks
Your dissertation on the L/D, induced drag, parasite drag and total drag reminds me of primary flight training. A good visual example of 'getting behind the power curve' can be seen in videos of the 'Sabre Dance"{F-100} and the F-16 crashes when dropping below the minimum speed on landing approach. Even an above-1-1 power to weight ratio can not assure recovery from this attitude. Love your videos, and the fine details brought forth. A refreshing break from mainstream, myth-ridden history of all these fine aircraft.
I calculated the power in KW of the Me 262 from my knowledge of physics and data from books in the early 90s and came up with a number so high I assumed I had made a mistake somewhere. Later I realised it was just due to the nature of gas turbines.
Yes, that increase with speed throws a lot of people off, few people understand it.
I see a Greg video, I click and like instantly. This is some really high quality stuff. Keep up the good work!
Yuki, my son's dog is named Yuki, he like anime.
Three quarters of an hour full with interesting, comprehensible content, in a way my lecturers would be jealous of if they could fit it into one week of readings; ends the video with "thats all for this video".
Thanks alot for your efforts.
That put the P51 versus ME262 Hollywood dogfights into perspective. There is just no possible way that a piston engine fighter can sustain a dogfight at reasonable speed with a Jet. On the lower speed range it appears that the Sopwith Camel can easily out-turn the P80 and ME 262. The future belongs to the Sopwith Camel!
Very interesting, as a mere life sciences grad, the non intuitive maths is very enlightening and obvious when you think about it which of course I didn’t initially 🙈 Thanks for a mathematical workout - I always learn lots from your videos Greg!
From the perspective of pure physics (or mechanics, rather), the concept of "propulsive power" goes as follows:
The definition of mechanical work is W = F s (force applied over a certain distance).
The definition of power is P = W/t (work done in a certain time).
The definition of velocity is v = s/t (distance crossed in a certain time).
Substituting the above to the equation of power, you get
P = F s / t
...and since s/t equals velocity, the equation for power can be written as
P = F v
or, "power is the product of force and velocity". In aircraft context, the force is the thrust, and velocity is the true airspeed. In other words, the "power" is the rate at which the aircraft is doing work (moving through air) against the drag force (which at steady state flight is equal to thrust). By the way, the units in this formula should be SI-units: Newtons for force and metres per second for velocity, which will result in power in watts. Using other units requires corrective factors, as was shown in the video. All of the formulas in the video were correct, though in my opinion unnecessarily complicated because of US Navy... ;)
This concept of "propulsive power" is physically very real thing, but I find it a bit of an esoteric concept. At sea level where true airspeed is practically equal to calibrated airspeed, it makes some sense and can be a reasonably useful tool for calculations. Otherwise, its usefulness is limited and in almost all situations it's more sensible to just refer to the jet engine's performance with its thrust.
The thrust of a jet engine varies with airspeed, so using values from static thrust measurements doesn't necessarily give correct results at higher airspeeds. In fact, treating thrust as a constant value is almost bound to produce incorrect results, especially when you're trying to calculate sustainable top speed or maximum sustainable rate of turn (which is the same as calculating the top speed but with increased load factor). It can give you a ballpark figure for sure, but in practice you would have to look at how much actual thrust the engine is producing at a particular airspeed.
If the difference between static thrust and thrust at particular airspeed is significant, then it could obviously affect the estimated sustained G-force in turn as well.
A typical thrust/airspeed curve shows a high value at zero airspeed (static thrust), then it starts to decrease due to drag losses, then it starts to go back up due to ram air effect assisting in the compression of air. Some jet engines actually produce more than static thrust at very high airspeeds (though I don't think any of the WW2 era jets did that). The design of the intake and the engine itself obviously affects this a lot, and considering the P-80 and Me 262 used very different engines (centrifugal flow vs. axial flow compressors) and different intake ducting, I would expect a big difference in the thrust curves of these two aircraft. The P-80 would probably have more channel losses simply due to the length of the intake ducting and the amount of turns the airflow has to make, while the Me 262 would not be affected quite as much.
On the other hand, the P-80 had the engine concealed in a fairly streamlined fuselage, while on the Me 262 the engine nacelles were out there in the wind, so the difference in parasitic drag would also make a difference.
The formulas I used are straight out of the book I referenced. You may view them as unnecessarily complicated, but I'm not sure what I can do about that. The formulas you put up are nice, and certainly correct, but I think you understand why I have to go with the official stuff in my videos, at least official in terms of pilot training. Regarding thrust varying with speed. yes, it does do that. I mentioned it, and I put up the chart from the book showing it. Since it's a small variation that we have no way to quantify in these planes, I felt it made sense to leave it out of the calculations. Frankly I'm much more worried about the possible error with the 262's clean stall speed, that's the biggest possible variable here. Thanks for your post, it's quite good.
Thanks for your description of jet power. I find it's a difficult concept to grasp, but it helps to think of it as the rate of work done to oppose drag.
By the way, did you mean 'then it starts to go back *up*' in your second to last para?
@@ltflipper2 Yes, thanks for the correction.
@@GregsAirplanesandAutomobiles I understand the reason why you put the formulas in as they are in the source material, and why the source material has them in that form - because they want to keep using one unit for one thing (pounds for thrust and knots for airspeed in this case). Mixing and matching units is known to cause confusion, resulting in a wide range of accidents - from airliners running out of fuel (like the Gimli Glider) to Mars probes crashing due to software not doing unit conversion correctly.
I didn't mean that comment as a critique of the video, but just to point out that the physics equations themselves are simpler than the equations used in the aviation textbooks and such. That is the advantage of using SI units - the equations can be more representative of the underlying physics, while the more archaic units (like knots and pounds and horsepowers and such) always require some seemingly random numbers inserted into the equation to make it spit out the numbers in the desired archaic units.
Regarding the thrust variance of jet engines, I understand that sometimes there's just not enough information to work with and in those cases, using what you got is fine and usually gives results that are at least somewhat comparable to each other. The thrust variance was recognized as a possible error source, which is good.
There are theoretical ways of estimating the thrust variance as a function of airspeed but without some computational fluid dynamics simulation, you'd have to do some guesswork on how the airspeed affects the flow rate through the engine - and sometimes, it's just best to minimize guesswork altogether and use the available numbers even if you know the results aren't going to be 100% accurate. In most cases the results are at least going to be comparable to each other between different aircraft.
Luckily there is some information about this old tech - fragmented as it is, there is this image that looks like it comes from an original German document: i.imgur.com/qtQBoKo.jpg
Unfortunately I don't know exactly what document that image comes from, so I can't tell the exact context - except that it supposedly shows the thrust curves of a Jumo 004B engine at different altitudes and airspeeds. From the document, we can see that at sea level (H=0), the static thrust is almost 900 kgf but drops quickly as airspeed increases, going as low as 680-690 kgf at airspeed of 400 km/h, and then picking up towards higher airspeeds.
Since the difference can be as high as 25% of the full static thrust, I think it's fair to say it should be factored into the results, especially as the biggest thrust reduction effect happens just around the airspeeds mentioned in this video - 400 km/h is roughly 250 mph or 216 knots.
@@HerraTohtori The pic is in Russian (from their own after the war testing, may be?) and gives not only the curves of the engine thrust for different heights and speeds in SI units in the lower part, but also in the upper part the curves are the fuel consumption in kilograms per hour for a kilogram of thrust for the same heights and speeds, presumably for a single engine.
GREG IS BACK!
Praise the lord of airplanes and automobiles!
I had a unique opportunity about 12 years ago to sit in a REAL ME262. My Dad worked as a volunteer at the US Air Force Museum in Dayton, Ohio. Once a year they had an employee appreciation dinner & also opened up several planes that you can climb into. I noticed they actually had the ME262 canopy open so I climbed in, I was amazed at how few instruments were in it. That same night I sat in a P-38J Lighting, an SR71, a P-47 & the B-29 "Bocks Car" that dropped the A-bomb on Nagasaki. Quite the evening! (They don't do this anymore by the way).
Wow, what a great experience.
I had heard the 263 was originally to have a straight plan form wing. However the Jumo engines were front heavy, so they returned the centre of balance by sweeping the wing, thus moving its CG to an ideal, just to the pilots rear as intended.
Ahhh Greg, I can see you love this stuff.
Me too, now too old to remember stuff, in order.
But you give me delightful insights in the stuff
I have always loved.
Thank you so much.
Your analysis of aircraft is absolutely amazing. Your knowledge of the subject matter and the way you present it makes your channel the best on the internet. You find in depth information on each aircraft, then explain to us amateur armchair critics what it means. Thank you for your hard work and dedication.
26:40
If you using excel or pretty much any other spreeadsheet software, you can change a setting in the graph making them interpolate any value between giving a really good estimation if intermediate values.
Great art at 11:26. I enjoy your outstanding explanations of aircraft and auto performance.
The art is straight out of the 1945 P-80 pilot's manual. I like to use that because it's free, historically relevant, and I just like it.
It’s good stuff!
Top notch. Clear and relevant to jet aircraft performance. Kudos!
I didn't understand all those words, but i found the video very interesting! Thanks Greg!
Fascinating - Im not a great fan of theortetical maths but when it becomes applied like this I seem to reach for my pencil and a spreadsheet!
Amazing video, the way you explained all these aerodynamics is incredible. Amazing video, hard to find such quality on UA-cam
Hi Greg! I would love to see you do a video comparing characteristics of early Jet fighters with late "Superprop" fighters. For example, why do early jets have such horrible acceleration at low speeds?
Most early jets were slow to spool up, and in the case of the 262, it has a lot of induced drag at low speeds.
Greg thank you for all your hard work! It's always a pleasure watching your content.
Thanks Stefan
To clear up the correct spelling of the ME262‘s name...
I‘m german and very old 😂. In all older german documentaries, wochenschauen or pilot interviews it was always the „MEH zweizweiundsechzig“, means „MEH twosixtytwo“. Not „M.E. Two six two“.
I also noticed that in modern english or even german documentaries the BF109 is mostly called „B.F. One O Nine“ while german pilots called it the „B.F. Hundred Nine“ or some the „MEH Hundred Nine“ or simply the „Hundred Nine“.
I‘m not saying this is the official correct spelling but i noticed this has changed since the rise of the internet.
I think it was called the me 109 by the allies in english more often but language works in funny ways ig
Reminds me of my hungarian grandmother, she used to say years as for example: nineteen hundred sixteen. When speaking english
Another great book is Introduction to Flight by John Anderson. We use it in my university aerodynamics class. It’s very understandable and breaks down these similar concepts. However it costs money. Great video as usual!
Horsepower is defined as 1 hp = 550 lbs of force being applied at the rate of 1 foot per second. A knot is 1.688 feet per second so to convert from fps to knots, divide 550 by 1.688 and you get approximately 325.
Excellent, as usual, Greg - and one more demonstration of why, when I was young enough for it to be a possibility, I would have washed out of flight training before ever reaching the flight line. I understand the general ideas, but the actual math might as well be in Martian. Right after WWII, my dad went into flight testing for what was then McDonnell Aircraft, so these early jets are quite relevant to his experience. He never flew a 262, to my knowledge, but he did fly a P-80, F1H and F2H Navy fighters as they were being developed, as well as the XF-85 and XF-88 prototypes for the Air Force.
I think you would have been fine. Nobody asks you to do such math on a checkride, but they do expect you to be familiar with the concepts.
Presentation is excellent, clear, not overloading the viewers ("students") w facts all at once but building up lvl of complexity at just the right rate as well as non-biased - just factual & objective. Continue...
Also, waiting for Parts #3/4 of the FW190 lectures..whenever the Muse strikes
***** 5 Stars: would watch again
Thanks, I appreciate it. After I finish the P-47 series, which has one more episode then I'll be in a good position to continue the 190 series.
I just listened through 48 minutes of aerodynamics and aircraft flying theory while working from home, guess this is a new level of quarantine life
I'm glad I could help. I know this whole quarantine thing is pretty miserable.
@@GregsAirplanesandAutomobiles you are welcome Greg, I appreciate your deeply analytic content. I like airplanes and I am quite interested in this kind of information and I must say, congrats for the effort and RESEARCH you put on them.
Great presentations ,, I subscribed just now. One detail, however -> the sound quality of the couple vids of yours I watched... is like you are in a tin can. Not sure how other people get great sound.. just a detail. Thanks for making these presentations.
Great video Greg, it's always nice to see material from you. I'm afraid I'll have re-read it a couple more times to get my head all the way around it, but thanks for your work.
Hi Randy, that's pretty normal. I have to re read/re watch stuff all the time.
@@GregsAirplanesandAutomobiles Hi Greg, I have a question about flying and it occurs to me that you could explain it better then anyone I know. Recently I was looking at some stuffed airplanes on display and reading the explanation plaques on each. One, a U-2C, said that at it's cruising speed (?) above 70,000 ft, there was a 4 Kt difference between mach buffet and stall buffet. What does that mean? Can't quite get my head around that one either. Sounds like it was a bi+#h to fly!
Brilliant video Greg. Always glad to see the finer technical aspects of these great aircraft.
Hello Greg, sorry for the late comment but I have a question : at 44:00 you are calculating the amount of G's an Me-262 can sustain, yet when I do the calculation : square root of (3940 which is the engine thrust - 1251 which is the parasitic drag):300 I get 3.03 , while in your video you say 2.88, you presumably accidenctally even mention it having 3600 pounds of thrust but even then it doesn't work, am I missing anything?
I'm hooked. Fantastic videos! I'm learning so much by watching them.
Every bit of this is fascinating. I don't know if you do requests. If you do, I would love to see a bit of a breakdown of the flight/performance characteristics of the F-104 Starfighter. How that teeny wing does was it does, is magic.
Thanks, I don't want to get into the F104 right now, you might ask ua-cam.com/users/Millennium7HistoryTechvideos .
@@GregsAirplanesandAutomobiles Thanks for responding and thanks for the link. I kinda figured but I thought I'd ask. You're a busy guy. I can't imagine the work that goes into your analysis. I'm not sure how you find the time to sleep, much less start any new projects. Have a good day.
Great video with very good and detailed examples explained in a manner that was easy to comprehend.
Thanks so much for making these. I learn a lot from it and feel I can trust it because you show your workings and sources. Great job.
Thanks for watching. I do try and not only list sources, but put the actual pages up (they are not copyrighted) so you can pause if needed and read it for yourself.
Retired pilot here... Keep up the good work. And I salute you.
Thanks Mike, I hope you enjoy retirement.
@@GregsAirplanesandAutomobiles
LMAO... Well, to be honest, it sucks. Just saying.
You could always go fly for Ameriflight.
@@GregsAirplanesandAutomobiles
Well, yes. I could... But the entire bummer of ad hoc 135 is what convinced me to retire in the first place. So I'm thinking that maybe a better plan is to rent some hanger space somewhere and start building BD-5's or whatever.
Last time I had this much fun is when I discovered "Aircraft Design: A Conceptual Approach" by Daniel P. Raymer. Keep up the good work, Mr. Greg.
Thanks Stefan
Great work as always, Greg! I have been learning so much!
Just want to say that if you do velocity in m/s, and thrust in newtons, you get kW without needing a correction factor.
Why I like working in SI units.
That crap is too easy and it will rot your brain. That's why the Americans never complain if the units are in Metric, because they can understand both.
I learned something today, thanks Greg!
Thanks Paddy. I really like your Spitfire and 190 chase video. That's some great footage you put up.
Spectacular job, Greg. Much of it is over this mathematically challenged guys head, but I get the results just fine.
Thanks!
As always, your video answers a great number of "why" questions. Super!
Only 8 minutes in, but my god do you make it easy to understand, wow!
New 48 minute video from Greg? Well I know what I’ll be doing for the next 144 minutes.
No no no. 144/48 = 3. "In aerodynamics, it's always a square or a square root". It should take you 48/(1/sqrt2) minutes to watch the video, the first time. If you have enough excess power to sustain that rate. Personally, I got GLOC a few times in the video and had to pause it.
@Jan Graham, LOL.
@@GregsAirplanesandAutomobiles I shoulda said Greg, great video. I was an aeronautical engineering undergrad and this took me straight back to Mechanics of Flight lectures, and dreams of slipping the surly bonds of earth and dancing the skies on laughter-silvered wings. Happy days, man: great video.
I believe the 262 was designed to cause allied pilots to poop their breeches. When asked about the 262 (which he loved) Winkle Brown said, quite enthusiastically, "power, power POWER".
Good to see u back Greg!
Thanks Asif!
Unless I missed it the numbers used in this video were for sea level performance, correct? How did the effects of altitude change the graphs? I am assuming that the changes in power output of the two A/C engines is not identical at altitudes and that an A/C with thrust advantage at 15,000 FT may not have that same advantage at 32,000 FT. Also because indicated airspeed and true airspeed diverge in increasing amounts as altitude increases and indicated airspeed is what determines aerodynamic performance won't the A/C with the lower stall speed gain relative advantages at higher altitudes? I have read that the ME262 performance decreased substantially above 24,000 FT. Just how did the effects of altitude differ for these aircraft?
Hi Keith, it was in the video, but easy to miss. All the numbers I used are at sea level and airspeeds are in CAS MPH. The primary purpose of this video was to clairfy some principles which will factor into further comparisons in later videos. To keep everything simple (relatively simple), I kept everything down at sea level specifically so I wouldn't have to cover power decreasing with altitude, and the True vs. Calibrated, vs. Indicated airspeed issues. In other words, as I stated, this wasn't intended as a total comparison of the two planes, but rather an explanation of principles, in which we gathered some comparative data. Now, in aerodynamic terms, yes the plane with the lower stall speed will gain advantage with altitude, and both jets will loose power up high. None of that is covered in this video. I am planning on covering that when I get to the TA152.
@@GregsAirplanesandAutomobiles Thanks for your reply. I am unsure of the differences on the compressor stage performance in the engines in the P-80 and the ME262 but I was surprised in altitude performance of the ME262. Was wondering how the P-80 did at higher altitude Vs. 262. Interesting to see how you constructed the performance profiles of these aircraft. I would add, though that you would only see these numbers in a wind tunnel environment.
TA152 should be interesting VS P-47M with late engine MP and RPM specs as related in Pratt Whitney tech notices. Looking forward to it!
One useful thing to realize is that power, horsepower is just an abstract construct used to help us with performance calculations and comparisons. It's not something we can measure directly, there's no horsepower-o-meter. What we can measure are force (thrust), torque, speed, and convert them to power using mathematical formulas.
So instead of thinking too much about abstract propulsive horsepower doubling with speed (sorcery!), it's easier to think about the measurable force applied on an airframe, which is engine thrust. Jet engine thrust does not drop down with speed, which is a huge advantage over prop driven aircraft, because propeller thrust drops down considerably as the speed increases. And falls of a cliff when the propeller goes supersonic. That's the reason jet vs. prop power diagrams look like they do on the video.
On the other hand, propellers generate a lot of thrust at low speeds, that's why turboprops are still a thing.
Michal, that's a great post, thanks.
@@GregsAirplanesandAutomobiles Thanks. I'm not trying to correct the video by any means, I just thought I'd write what helped me grasp this topic some time ago.
Outstanding detail, as always. Thanks for the video.
Thank you Greg, you make perfect sense
For impatient - formula is @ 18:04 :)
Very informative video btw, you could mention that power loading for turbojet engine is different than for turboprop or turbofan of the same thrust, which have lower disc loading - and thus need less power (hp) for the same thrust as turbojet.
Thanks, I should add that time stamp to the description. Probably one for when the video gets to the comparative drag data as well. I understand that the entire video is a bit much for some people. It's not aimed at the masses. I thought about power loading issues, but the video just came out way too long as it was, I was aiming for 20mins.
Technically you can also calculate horsepower for a jet engine as thrust power, which is different (and much less useful) than propulsive power.
In this case, you use the velocity of the exhaust gas in place of the velocity of the aircraft. Unfortunately it's hard to find information as to the exhaust velocity for the 004.
However, as best I can tell, it had a max exhaust temperature somewhere in the region of 670C. Using kinetic gas theory, that translates to about 750m/s, or mach 2.2
That produces about 3.3MW per engine, or about 4400hp, for a total of ~8800. Of course this figure is mostly only for academic interest, it's not very useful for flight performance.
About the only real world application it has is determining how much damage a jet engine will do to something directly behind it.
Thanks Brent.
*Greetings...Plane Whisperer....you have 100% of our attention*
Informative work as always. Learned quite a bit more about stuff I never knew about.
Hi again Greg. Here it goes. I apologise for the length but please read it through before disregarding any point as they are all related.
1- At around 6:15 you say the green arrow is the resultant of the force generated by the wing. I agree, it is the vector addition of lift and total drag. Then you say there is a rearwards component of this force, the red arrow, correct. But then at around 6:30 you say "this rearward component of lift is the induced drag". The statement is correct, the induced drag is the rearward component of lift, but this red arrow is not the rearward component of lift. As you have already said seconds before, the lift is the vertical black arrow, hence it can't have a rearward component. The red arrow is the rearward componet of the total resultant force on the wing, the green arrow, and hence it is the total drag. Please bear with me until the end of the post, because I'll try to explain how the lift is tilted rearwards in a finite wing and thus generates the induced drag, which it really is the backwards component of lift, as you said, but not in the way you are showing in this diagram.
2- At 6:43 you show a quote from AFNA that is, of course, correct. But please note that it says explicitly "finite wing" not just "wing". Why would they bother to state this considering that all real wings on all real airplanes are finite and no infinite wing exits or can exist? It seems unnecesary to say it, doesn't it? The answer is because the wings being finite (i.e. they have wingtips) is the ultimate cause of the induced drag. Please, again, bear with me until the end of the explanation.
3- Your explanation starting around 06:15 disregards this and it could be applied exactly as it is to explain induced drag for an hypothetical infinite span wing (i.e. a wing without wingtips), but infinite wings don´t have induced drag as the quote from AFNA of point 2 above implies when it explicitly says "finite wing", when it would seem unnecesaty to state it.
4- How then is the induced drag created if the lift vector is always perpendicular to the airflow as you shown with the black arrow at around 6:15? Because the wing being finite, and this is the key point, there is a circulation of air from the surface below the wing to the top of the wing around the wingtips due to the pressure difference between both surfaces. This circulation creates a spanwise flow of air (from the wingtip to the wing root on the upper surface and from the root to the wingtip in the lower one) and the wingtip vortices. All this tilts downwards the airflow the wing encounters locally (i. e. the "downwash"). If the airflow is tilted downwards then the lift vector is tilted backwards, as it is perpendicular to the airflow by definition, hence now it has a component in the horizontal direction and pointed backwards: the induced drag, exactly as you said and quoted from AFTA from 6:42 to 6:45 but didn't quite draw correctly in the diagram. If you had considered this you'd have drawn the black arrow slightly tilted to the rear and explained why in a similar way to what I just wrote here.
5- Further, albeit indirect, proof that the induced drag is created by the wingtip circulation flow, as indicated in point 4, is the fact that some airplanes have winglets in the wingtips. Their purpose is to reduce this flow which in turn reduces the induced drag.
Please consider that this is not the explanation of a random guy in youtube. I just tried to summarize the best I could and without the advantage of diagrams the explanation given by John Anderson, who is the Curator of Aerodynamics of the National Air and Space Museum Smithsonian Institution and Professor Emeritus of the University of Maryland, in chapter 5 of his book "Fundamentals of aerodynamics" 6th edition published in 2017.
I am not asking you to accept my word, I am just asking you to check the book for yourself. How difficult can this be for someone that has been searching in 70 year old documents to get data for a comparison between the P-80 and the Me-262? I even offered to send you pictures of the relevant pages. It is not in contradiction with your quote from AFNA, they agree. It is your diagram that fails to acknowledge the source of the induced drag, the downwash created by the vortices created by the flow around the wingtips.
So, I think I tried to the best of my ability, now I leave it in your hands. I can´t do anything more without repeating myself over and over.
Just one more thing. To give credit where is due I quote some paragraphs from the book that are much better than anything I could possibly write:
"In chapter 4 we discussed the properties of airfoils, which are the same as the properties of a wing of infinite span; indeed airfoil data are frequently denoted as `infinite wing´ data. However, all real airplanes have wings of finite span, and the purpose of the present chapter is to apply our knowledge of airfoil properties to the analysis of such finite wings."
"Question: Why are the aerodynamic characteristics of a finite wing any different from the properties of its airfoil sections? Indeed, an airfoil is simply a section of a wing, and at first thought, you might expect the wing to behave exactly the same as the airfoil. However, as studied in Chapter 4, the flow over an airfoil is two-dimensional. In contrast, a finite wing is a three-dimensional body, and consequently the flow over the finite wing is three-dimensional; that is, there is a component of flow in the spanwise direction."
"The tendency for the flow to `leak´ around the wing tips has another important effect on the aerodynamics of the wing. This flow establishes a circulatory motion that trails downstream of the wing; that is, a trailing vortex is created at each wing tip"
"These wing tip vortices downstream of the wing induce a small downward component of air velocity in the neighborhood of the wing itself [...]. This downward component is called downwash [...]. In turn, the downwash combines with the freestream velocity to produce a local relative wind which is canted downward in the vicinity of each airfoil section of the wing."
"The presence of downwash, and its effect on inclining the local relative wind in the downward direction, has two important effects on the local airfoil sections, as follows:
1- [...] Although the wind is at a geometric angle of attack, the local airfoil section is seeing a smaller angle, namely, the effective angle of attack. [...]
2- The local lift vector is aligned perpendicular to the local relative wind, and hence is inclined behind the vertical angle [...]. Consequently, there is a component of the local lift vector in the direction of the airflow; that is, there is a drag created by the presence of downwash. This drag is defined as induced drag."
I read all of this, but I'll have to respond in pieces due to my other obligations. I'll take point #1 first. That diagram is something I made in Paint, it's intended to give an overall picture. I clearly said in regards to this diagram that it's a bit simplified. Still, let's go over what I said. I said "the force being generated by the wing is represented by the green arrows here, the lift is the vertical component, however there is a rearward component". Now I am clearly talking about the green arrow there, which you apparently didn't hear. Now in the next sentence I do refer to that as the rearward component of lift. I did that to be in harmony with the statement from AFNA which I put on screen seconds later. As for your statement that the red arrow is the total drag, that might be true in another context, but the context of the discussion at this point was induced drag, we were not talking about other types of drag.
@@GregsAirplanesandAutomobiles Greg, I am sorry but if the green arrow is the total resultant force on the wing as you say in the video, the red arrow (its horizontal component) can not be the induced drag. As you yourself said the induced drag is the horizontal component of lift, not the horizontal component of the total resultant force on the wing. Now, if you say that the green arrow is the lift tilted backwards by the downwash, I agree, the red arrow is the horizontal component of lift and therefore the induced drag..
No, I didn't say anything about downwash. I am also not saying that the green arrow is the "lift tilted backwards by the wing". Lift is clearly defined as being perpendicular to the relative wind. Lift being tilted backwards is not a part of the definition. That's the reason I added the green arrows.
Superbe. This is a primer for me. I am studying this. I will also download the aviation book. Love this stuff.
Hi edo, I'm glad you like it.
My favorite youtube channel!
Pretty darned interesting. The concept of a piston engine not rotating a crankshaft at 20:34 might be able to use the average piston speed as your linear motion rather than the rotation of the crankshaft. What happens when you apply the same logic to a piston engine/propeller driven aircraft and determine it's relative propulsive horsepower, since you show a beautiful Packard built Merlin in your video, use a P-51 and a Spitfire in their top of the line designs for a similar comparison as the 262 vs the P-80? I see there's one for the P-51 vs the (which version, BF or ME?) 109 so half the comparison is already done. It would be very interesting to see how the numbers compare given two airplanes that are so dissimilar and yet used the same engine. Just for giggles and fun how about a later model P-47.
Discussing the F-14 reminds me of the demonstration they used to do at the Point Mugu Naval Air Station "Space Fair". The F-14 would do a 360 degree turn while keeping between the runway and the perimeter of the base. It was both scary and very very impressive both of the plane's capability and the pilot's ability to fly in such a edge of the envelope maneuver. He would be in a near 90 degree bank and full afterburner and you could see the pilot changing the bank angle constantly to avoid going over the edge. He did this only 150 or so feet above ground level, if that. I doubt he would have survived had the airplane stalled. Personally I think the navy gave up a huge advantage in air superiority when they retired the F-14.
Yep. Very interesting video. Otherwise I wouldn't have such a large comment. And near the end you did mention propeller driven aicraft but not a comparison of the 2 different planes with the same engine that I suggested. I won't kid myself that I could do it myself because I can't. I also won't kill myself is you never do it. But I do intend to watch your other videos.
Thanks
Chris
Hi Chris, I saw the Blue Angels perform in F4 Phantoms at Point Magu when I was very young. I just flew into Point Magu myself a couple weeks ago and talked to some Navy pilots. It really brought back memories.
Another informative video Greg, great stuff.
Very well done. Outstanding specificity.
hmm... since you mentioned later upgrades, could we consider the newer Me 262 with GE engines in comparison to upgraded P-80's and late war meteors too? would be quite interesting to compare the newer frame (altho not as fast on the deck for safety reasons...).
For the 262, are there numbers for lift, drag, Vx and Vy from the modern replicas that are flying? You could then adjust for the engine difference between original and replica.
I don't think so, but maybe.
it would be really interesting to compare the ME262 to the Gloster Meteor as they had a real chance of fighting each other in 1944-1945. The Meteor had been held back in UK to take out V1s and also the British didn't want to lose one over enemy lines. I believe they would've been a closer match than most people think.
Most low altitude max climb rates in a jet are accomplished at a constant indicated or calibrated airspeeds. This requires a small amount of acceleration to maintain, while small, is not zero and is noticeable.
Perhaps you would consider doing a video on the British Electric Lightning F6. I'm a big fan of that one!
Just thinking. The turbine section drives a shaft that, in turn, drives the compressor section. There is some measurable hp there. The accelerated exhaust being the source of propulsion that is hard to calculate into hp.
Yes, we are talking about propulsive horsepower here.
Great video as always. Fascinating!
My flight instructor told me one pound of thrust equals one horsepower at 375 Mph. I find that useful to do a quick calculation of power because I have difficulty conceptualising "thrust" compared to HP.
That's correct, or close enough, 325 knots is 374mph.
Think about it this way: A piston engine, propeller driven plane uses the propeller to convert the engine's horsepower into thrust from the burning fuel. However, the turbojet engine uses the burning fuel directly to produce thrust. Either way, it's the thrust produced by the engine that is acting against drag, not the engine's "horsepower".
Glide distance (glide slope) will vary with weight because as you increase wing loading you shift the induced drag curve to the right and the lowest drag value will also increase.
Aerodynamics for Naval Aviators disagrees with you, specifically pages 32 and 33 if you want to look it up. Here is the quote: "An unbelievable feature of gliding performance is the effect of airplane gross weight. Since the maximum lift-drag ratio of a given airplane is an intrinsic property of the aerodynamic configuration, gross weight will not affect the gliding performance." You can go to the actual source for more info on this if desired.
@@GregsAirplanesandAutomobiles Ok this checks out at low Mach. I was thinking of airliners which glide worse when they go faster.
That's correct, at high speeds glide distance decreases because you are getting too far from the optimal speed. Best glide speed in an airliner varies a lot with weight, but the glide ratio stays the same. I'll use a Boeing 767 since that's what I fly. Best glide speed in this plane happens at Vref +80 which is the minimum maneuvering speed with the flaps up. At typical weights this is about 230 knots, but at or near max weight it's around 254 knots. The speed can actually be pulled up on the CDU. Actually, you pull up the best angle of climb speed on the display, but that coincides with best glide speed in a jet airplane. (source AFNA page 32).