Hi Jay; thanks for featuring my J44 in one of your videos! I am honored. Let us hope that I can get it all back together and running once again, restoring and helping to preserve a small piece of the history of gas turbine engines. It is a fairly simple engine , disposable, if you will, so that is a good start for us moronic beginners. The compressor is a mixed flow type, with 'impeller' and a 'compressor' pieces mated together. The two parts are actually two different metals; impeller is aluminum and the compressor is magnesium. Those turbine blades are actually welded to the disc! That is hard to believe but if you look close, you can see the two different-looking metals where they join together. Mark pointed that out, otherwise, I assumed that the 'blisk' is one piece as manufactured! The last version, the 'flight rated' J44-R-3, used the individual blade design, with a rotor disc, replaceable blades and keepers. All of my aluminum 'test stand' was designed and built by Mark of BoMar Industries, as well as that shipping package. Those boards were cut from a 4' x 8' sheet on a Mazak laser cutting machine! He is a friend that likes to trade favors so I have his talent and vast shop to help me out at times. Thank you to Mark for his time and efforts on the J44 Project. He made the stand itself, the engine mounts (Soon to be modified so that the rear mounts will slide axially, to allow for thermal expansion, per Jay's recommendation!) and the ignition exciter unit mounting bracket. Oh and the special spanner socket to fit the compressor stub shaft nut. Fragment sentence; sorry Graham. Last but not least, thank you Jay for taking the time to mess with my pissy little project, just a hobby for me, in your real world of gas turbine engines! Many jet shops would not want to bother with such a job. Thanks for your services and I intend to video everything; reassembly, checking clearances, reinstalling it on the stand, then, finally, firing her up! I am shooting for sometime next Spring. If you watch my "J44 3rd & 4th Runs!" video, it has a different set of sound characteristics, due to the GoPro cam being in its water tight case. The 'louder' jet sounds (high velocity gases rushing) are muffled enough to allow us to hear those sounds traveling through the stand and to the camera through its mounting (it is mounted on the stand cross-brace in the center, facing towards the rear (exhaust) end. Besides the fuel pump noise, heard at first, you can hear 'shaft' or 'gear' type noises that change with the speed of the shaft, up to idle speed. There would be some gear noise from the accessory drive box but some of that noise could be from an imbalance. It will interesting to use the same camera location and video a run, then compare the sounds! I am gonna bet it will be 'quieter'! I had a shot of moonshine (bought in a store, legal, some 'Tim Smith's'!) a while back when you told me you had the rotor balanced! To me, it is 'Voo Doo', the art of balancing an assembly! A disc I understand but an assembly, no. Thanks again and cheers! DD
Very cool channel! I'm studying for my aircraft technician license, and a teacher showed us one of you videos on jet engine bearings. Educational stuff, keep up the good work!
I've had the turbine bug since the summer of 1999! I went on a trip with EAA explorers to Denver CO to visit various aerospace manufacturers, I was into electronics, computers already at that point, when I got the first sight of the engineering beauty of the first commercial turbines I was able to examine closely, I remember it was at the old Denver international airport not long after they opened the then newer Denver intl. airport. When I returned home, I started on a turbine project, I quickly figured out from a then few other turbocharger based gas turbines, that I would build a turbocharger based turbine with a T3 turbocharger. I was able to purchase two junkyard T3's from donor cars, I believe they were both '80s 4cyl dodges, first I quickly figured out from a local retired Boeing engineer that I needed to work on the combustor first, back then the info. on these type of projects was scarce compared to today. I built a combustion chamber carefully over the fall into the spring of 2000, I tested several designs with a chamber - case made of a high nickel stainless, it was 1mm thick and welded by a local welder that did a superb job! I tested using an electric leaf blower and carefully placed thermocouples. I purchased rebuild kit for one of the T3's. with beryllium alloy bearings and new balanced compressor, and tested with the rebuilt T3, the rebuild kit was around $200 then, today you can get an entire T3 for $200, I did purchase a new T3 kit springtime of 2000, it cost over $600 then, with a ceramic bearings (zirconium oxide) kit, a $200 additional cost, which then ceramic bearings were a new 'premium' feature. By May 2000 it had its first run, now was time to build a controller, which then there weren't the easy to deal with arduinos or like hobby control boards that a plentiful today, at the time the Microchip PIC16F84 was a good choice, it is a microcontroller that is flash re-programmable, used to time & control everything for start-up, idling, throttle input etc..., I wire wrapped the control board, instead of acid etching test perfboard(s), which I later produced a finalized control board this way, It hasn't been installed permanently into the final setup. The complete turbine in its final current example, which I still own, was started around Jul 2000, and is still setup to run on propane, it still runs, as I am asked to bring it to the local vocational school fair once or twice a year, I still know the teacher at the high school, he will request me to show it a few times a year as well. The only things I've added to this turbine is, I've built an additional swap-able exhaust nozzle, one with chevrons & one without, and will run them one after the other to show how chevrons reduce exhaust noise, as well as a different intake with an acoustic tube, also to demonstrate noise reduction.
Mooted: That this young man be proposed for an Honorary Degree. For services above and beyond the norm. For exceptional educational value. For dedication to clarity of understanding.
love the vids u have on here, Im one of two rotor techs in the company i work in in england, we inspect , strip and build and low speed balance Seimans TA 1750 ,Tornado ( sgt 200 ) typhoon ( sgt 100 ) tempest ( sgt 300 ) compressors with the HP/LP discs , love the challanges of building and balances these girls ,Would love to aspend time with u guys ,
Must say I was wincing when I've seen the whole (well, half of :) ) rotor assembly resting on the turbine blades. As I have no doubt you know your stuff this is news to me: turbine blades/blisk are much stronger then I would have guessed just by looking at it! :) Thank you very much for all the videos you made. My four flights on jet airplanes at the end of october were much more fun after seeing all your videos and knowing what's going on engine-wise!
As I've said elsewhere, for those concerned about two blades taking the weight of that end of the rotor when it was on the table: don't be. The two were each only just off the vertical and were acting as struts in compression. Using a pair of Mk.1 eyeballs, calibrated with some experience, I reckon they would have been more than strong enough . Nevertheless, I couldn't resist doing a few very rough calcs, which I won't go through here, but I reckon that the gas bending load on each blade will be at least 50lb and probably a good deal more. I wouldn't recommend it, but I reckon that, if AgentJay Z lifted the rotor off the table with an attachment at the impeller end, plus a pair of strops around the two blades on the horizontal centre line of the turbine disc, then they would take the load quite comfortably ..... probably.
Ah, life is good once again. Nothing beats watching the master work his craft. Hope the beard comes off soon. having a home with workers in it all the time can get very, very tedious.
You can put a little Sharpie marker dot next to the nuts you have torqued, using multiple colors for multiple passes. Though a visual inspection for preexisting marks and mark-like marks would be necessary. They often do it on bike for "safety" fasteners. [I remember when my brother left a bolt loose on a car-engine flywheel, and the ticking sound it made as it tapped the clutch fingers.]
Man, you have so many cool tools and parts, and are having so much fun. And don't be skipping screws; it's like the sound of screechy chalk on a blackboard.
I don't know the "cost" of the Rolls Royce and Orenda wall plaques, but it took $6million for me to get a Solar jacket some years ago. They used to have some really nice jackets with a picture of a turbine embroidered in the back in color. I was told they only gave them out to Solar employees. The company I worked for at the time purchased 3 Taurus 70's for a power project. So I got my jacket!
Oof, that assembly is beautiful! As part of Phase Two of my project, I've been looking at upsizing a 7" compressor with various modeling methods to see if I can build one out of carbon fiber. Trying to find a compressor wheel that size in my 'budget' was getting to be a problem, but I look at this with envy! It's soooo big!!
Wow, the disk and blades are 1 piece. I don't even want to think of the amount of machining and finishing work that has to go into that during manufacture.
I've done only newer two spool high bypass turbofan engines mainly, which are usually balanced in many phases. Static balancing for disks and dynamic balancing for the whole assembly/stacked rotors/seperate spools. Blade positions are calculated by their moment weight for disks which needs it. One can shift the blade positions or add weights. Usually after grinding it is not allowed to shift blade positions anymore, and that's why most of the rotors are pre balanced before grinding. The machine shows unbalance or needed correction or whatever you have chosen it to show in weight and degrees in planes what you are balancing. Or at least the schenck machines do. Tolerances are given in various units like gram-inch, gram-millimeter. In test run some trim weights are added to the fan if needed.
I remember reading somewhere that the blisk versions of this motor were dangerous and they went to a conventional turbine wheel. Maybe the blisk versions were one time use like in a missile or target drone.
I was hoping to see the actual process of balancing the spool. For example; the speed at which the balance takes place and the calculations required as it is not at operating speeds. I am curious , do you confirm the balance after the final torque? I was suprised to see the assembly resting on the table unsupported. Thanks
Whats your opinion on that Boeing 767 American Airline that caught on fire last October. They said a turbine disc failed. Don't they checked those discs for cracks during schedule inspections?
Of course they do. However, if you had checked the NTSB website, you would have found a photo of the failed HP2 turbine disc sections and a preliminary determination that fatigue propagation had initiated from an internal defect. Such defects are by no means impossible to detect using the latest NDT techniques, but it would be a good deal more difficult. I'm not in a position to draw any conclusions or speculate as to why the original defect was not detected, nor why a crack wasn't detected in its early stages: I will leave that to the NTSB. Fortunately, such uncontained failures occur only very occasionally, but they do happen. We had an uncontained failure of an HP compressor disc in the engine of a BA B.777 at Las Vegas last year and, back in 1989, a fan disc failure that led to that crash landing at Sioux City. Years ago, R-R had several failures of both fan and HPT discs in early RB211s, but no aircraft were lost. The experience and investigations contributed directly towards improvements in both metallurgy and inspection techniques.
Good video thanks. At about 7:45, was that a bit of chewing gum or special putty on the back of the compressor disk, using it to mark where to cut-out?
Having spent time on smaller gas turbine engines, the turbojet kind that spins in excess of 40.000 RPM, this looks like a test weight. You can see that the cutout made to the compressor`s back side is 180 out of phase with this test weight: you measure the weight of this material, and subtract from the other side. This is a lengthy process as balancing must be done in smaller and smaller adjustments: you dont want to cut more than necessary. Also, notice how the cut is done as smoothly as possible to minimize the risk of metal fatigue. I am not sure if +AgentJayZ put it there, or if it was left as a starting point by the engine owner. Either way, it seems that it was close enough in placement, but quite smaller than necessary. When we worked on balancing, we used a rubbery adhesive (like gum) used in car body shops
They will be to create a defined pivot point for the blades to flex about as they heat up and expand. If the expansion slot is taken up and any pressure applied to the adjacent blade, the metal will happily flex about the lower pivot point.
Can you explain the reason for the complicated transition from the disc proper into the blades? In particular why there is that strange ridge on the blades that looks like it is joining them into another ring part way out? Does the air from the inner and outer part take a different route through the rest of the engine?
1- it has to be strong enough so the blades don't rip out under centripetal stress. 2- larger blades in older designs needed those points of contact with each other for support and prevention of vibration and oscillation. 3- in turbofans, yes. That's why it's called bypass air.
thats awesome could make a similar engine from a locomotive turbo or even a large ship turbo but especially an EMD turbo because it has a power takeoff from the hot section
Turbochargers are power adders for piston engines, and therefore can be considered slaves. Turbojets, even small ones, are complete engines on their own, and are free to propel small aircraft to speeds several hundred miles per hour.
So in this config if a blade gets badly damaged you are good to buy a hole new blisk ? .... Same question for resonance I know they it's a working design so it's not a problem, but isn't the hole turbine and compressor blade not attached to the main frame to avoid resonance ?
I'll jump in and tell you what either Darren D or AgentJayZ could tell you. The J44 was originally designed as an expendable engine for a drone application, so it was never intended to come back for repair and overhaul: if it did, it wasn't intended to last very long, so R&O was not an issue. However, as Darren D has pointed out, the engine was further developed to a "flight rated" standard - as was the dear old Viper, which also started life as an expendable engine and with which I am more familiar. Back in the 90s, we even had to 'convert' a 202 engine out of a Jet Provost into a 201, to go into a Jindivik - if you don't know what those aircraft are, try Wikipedia. I'm quite impressed by the the blisk design and manufacture of the J44, recognising that it would have been quite possible, but probably far more expensive, to machine the aerofoils from a solid disc. However, in those days, long before CNC, it would have meant a very laborious copy-milling process and a lot of work by a skilled blade polisher (or two). I saw some of that on much smaller turbines for helicopter engines when I was an apprentice way back in the 60s. If you're thinking in terms of a firtree root being necessary to provide some damping, well think again. There might be a small effect and you can certainly kid yourself when the blades clatter loose as the engine is running down. However, think in terms of up to 50,000G at the rim of a disc and how rigid a firtree root will be under that sort of load. And for those concerned about two blades taking the weight of that end of the rotor when it was on the table: don't be. The two were each only just off the vertical and would have been more than strong enough.
PS I couldn't resist doing a quick calc for that disc: its rim G loading will be about 30,000. The 50,000 I quoted would be more typical of an HP turbine in a modern engine.
Blisk technology is used on smaller engines, where the natural resonant frequencies of the blades are outside the range of excitation experienced during operation.
It still boggles my mind that these things run at such slow speeds! 10k RPM? Really says something about these large compressors efficiency, when my little Holset Hx40 needs to spin at 240k RPM to make boost! Friggin Incredible!
The speed of the blade tips is the important thing, this one's rated upto 15kRPM I think, and has a radius of about 10" (0.25m), which means the tips go about 375m/s, or faster than sound (in cold air, but the air will be hot so it won't actually be supersonic). A small turbine does more RPM to get to the same blade speed. A turbojet engine has to stay subsonic in the core (otherwise you'd have a scramjet!).
AgentJayZ R.I.P. Shop kitty :/ I hope there are a job opening for a Mk II, I suggest a Norwegian Wood cat ( skogskatt ) because they are social,friendly and have no inbred health issues. They can get up to 18 years or older.
Hell, if we're making Shop-Kitty recommendations, I'll vouch for this gray thing I rescued from the animal shelter that looks like it has a lot of "Russian Blue" in it's genetic background. Super friendly and confident cat. Godspeed Shop-Kitty I
Is there any particular advantage to a bladed disk / blisk over a turbine wheel which has individual blades fitted by those "fir tree" slots around the circumference? I suppose the blisk can be manufactured in one piece, but until I saw this video I didn't know they were made that large. I knew that smaller engines (like helicopter gas turbine engines) use blisks for their compressors and maybe for the turbines as well. Anyway, what happens if one of the blades gets damaged - do you have to replace the whole blisk? I'm guessing you can't just cut the damaged one out and weld a new one in, because the welded join would be weaker than the rest of the metal. Plus it would throw the balance out and probably cause many other problems.....
I believe the blisk was invented because a government contract for a new military engine was attempting to reduce costs. The specification was for a reduced parts count. Manufacturer says "Yes, sir! A 30% reduction in parts count!". Only thing is, it was more expensive anyway, and as you pointed out, repairs weren't cheaper either. You damage one blade in a blisk... the whole thing needs to be replaced.
Fair enough. I bet there were some questions asked and a lot of office stationery thrown around when the manufacturer submitted the final bill - and the civil servants thought "OK, they have reduced the parts count as we asked them to, but it's now more expensive? And what's this - we can't repair that large, expensive and rather vital component? We have to replace the whole thing instead?" I wonder if that's where Apple got their "no, you can't repair or upgrade your iphone / ipod / macbook in any way, you have to buy a new one" inspirational ideas from?
On civil aero's ie Trent XWB high pressure compressor it's for mostly for weight saving. FOD damage is a proper PITA necessitating being build up by welding and subsequently adaptively milled to recreate the aerofoil. You wouldn't design it like this for with no good reason. Although I'm not a mechanical integrity engineer I imagine the stresses would be lower in a RR style blisk as the root fixation stresses can be very high and not having discontinuities in the rim ie blade slots will also help - this doesn't apply to this arrangement. I'm not familiar with this engine but I suspect as it appears to be a turbine blisk it needs the expansion slots ...... A rough rule of thumb was that for every unit of mass at the disc rim necessitated double to be applied to the disc 'cob' or bore to contain the stresses.
I have a question about Axial compressors. You know how the compression happens when the fast air enter an expansion section of the jet-turbine? Does that mean that the air does not take up the entire space? If it takes the entire space and compresses by loosing speed, then there's a loss of energy for the expansion no?
I hesitate to answer, because I don't want to discourage your search for knowledge, but I have no idea what you are saying here. None of it makes any sense to me, and I'm not going to try and guess what you mean. As always, I suggest the first chapter or two of an introductory text on gas turbine engines. You'll see them often in my playlist "Your Questions Answered".
Not a jet mechanic, but pretty sure balance only depends on weight, it's not going to change as you tighten the nuts (unless you overtighten them so much it bends the thing).
From an R and D aspect: once balanced, installed and tested in the engine If you ever had to re-check the balance AFTER a test run, would you still find that turbine perfectly balanced or would you anticipate a bit of adjustment.
Interesting question... I feel like I am playing 3D chess with Spock. Why would I need to recheck the turbine balance after a test run? Because the vibes were too high. I would of course expect the turbine to be out of balance, because that's what makes an engine shake... ... ... ... eh?
I have had vibe issues with a bad batch of rear bearings and with coupling nut issues , its rare but it has happened . re-clocking of the turbine during installation has also been effective. What brought me to that question was that both Shenk and Hoffman balance machine reps have both indicated that some adjustment would be needed to balance the turbine simply by just removing the turbine off the balance machine and re-checking. Their answers bother me , lol. thanks though.
@@AgentJayZ we are tearing apart these j44s in class , instructor just informed us that green stripe is for heat detection, so if the shaft overheats the green turns into a orange or darker color and basically disintegrates. Neat I guess
I guess, but to know the engine is overheating, you have to disassemble it? Plus, the shaft is very well protected and isolated from the actual heat of the gas path. You can tell your instructor that I think he's pulling your leg... or maybe someone is pulling his leg. I'm not buying his explanation, but if he wants to reference a source...
It can’t have no reason for being there at all, if there was no reason there would be no green stripe. The look of it is way to specific for it to not have a function. #questioneverything
@@AgentJayZ I think the entire point is once you disassemble it, you will know once you see it, we can physically see as some of the ones that were green, are less green, some strips are orange/ dark red and some black and almost completely gone. So it seems to support his idea we’ve got about 6 of them disassembled in our hangar right now. I’ll check with him tomorrow and ask again. The manual doesn’t have anything about it but it doesn’t have much of anything I guess since it was written 10000 years ago lol.
No. They are powerful for their size because of their ability to burn a lot of fuel. There is a large rotating assembly with considerable mass to it, but when fuel flow is reduced or cut off, the deceleration of that assembly is instant.
I noticed that the end of the shaft on the hot side was damaged post balancing. It was not damaged pre balance. On your balance rig I see a small bearing on the hot end which I guess is used to keep the shaft from moving fore and aft. Did that small bearing get into the end of the shaft?
So, let's get this straight. You are saying that in the process of balancing this rotor, I damaged it? Based on what you saw, but are unwilling to refer to as a time in the VIDEO that you have just watched on UA-cam. Is that what you are claiming? I just want to be clear on this.
i cant even fathom the ability to learn what you have with these engines, you can break it down and im like WTF i still dont get it and then feeling of being an idiot sets in !
wow a blisk for a turbine disc? I assume the whole thing is dipped in fluorescent dye to check for cracks after manufacturing? whats that blisk made from? ti?
No, a turbine disc wouldn't be in Titanium, then or now. When the J44 was designed, I doubt that Ti was available and, even if it was, it would have been too expensive for a short-life expendable engine. I think that AgentJayZ has already suggested that the disc may be steel and the blades may be Nickel-based. However, in an engine of that vintage the blades could well be a heat-resistant stainless steel, particularly as the engine was destined for a short life.
it sorta has a stainless or Ni-Fe luster It seema like it would be much more difficult to manufacture that way compared to christmas tree rooted blades.
Fir tree blade roots and disc slots have to be manufactured to very tight tolerances (to within a couple of tenths - of a thousandth of an inch), so that the serrations share the load reasonably uniformly. Very specialised high precision machine tools are, therefore, required. An established jet engine manufacturer with such equipment would, no doubt, have utilised it to make discs and blades for an expendable engine. Armstrong Siddeley did when they designed and built the first Viper. However, Fairchild were primarily aircraft manufacturers and would almost certainly not have had such equipment. Assuming that constraint, the design and manufacturing solution that they came up with was (in my opinion) eminently fit for purpose.
I only just watched this video, from obviously a while back, but I simply wanted to ask, are you susceptible to flooding where you are, and is the snow melting earlier in the season? Just makin comparisons, as I have a friend that lives up north somwhere.
I hope I have not offended you. As a mechanic I know that no matter how careful I am, $hit happens. To me the shaft at the 7:55 mark looks a bit different that at the 10:15 mark. Perhaps I'm mistaken.
There you go. A time stamp is very helpful. It looks to me that the turbine disk was balanced by grinding away at an area supplied for just that. It does look like scarring. The marks on the turbine are visible at both of your time stamps, but the lighting was different. Being a tech yourself, I expect you to notice all details with an eagle eye. My goal was to balance the thing without any grinding. I managed to do that on the turbine, but the only way to balance the compressor was to grind, so I did. All of this was explained in the video. Did you watch all of it? Hell yeah you offended me. If you are gonna say I damaged something, you better be damned sure, not just guessing. There's no replacement for actually being there.
It is the same before and after balancing. I guess you were confused because the shaft was not at the exact same angular position after balancing, and you could see some marks on the hot end turbine at 10:15, which were not visible due to the camera angle on the turbine at 7:55. You can see the same marks at 7:55 too if you look a little bit closer to the far side of the turbine. And I am assuming those marks were scraped off for balancing the turbine in the first place anyway...
Johann Sebastian Bach Thanks for your explanation. I agree. It was camera angle. I didn't notice the countersunk portion on the end of the shaft in the first time stamp shot. That is what I was asking about but when things were getting tense I dropped it. lol.
Sorry, nitpicking warning as nitpicking coming up:. Strictly from a Metrology point of view, it is unlikely that your torque wrench has better than combined 1% accuracy so it is possible that setting your torque wrench at 227 could end up being a slightly below the specification requirement of 225 to 250.
Sorry, I only heard where he set them to 227. My brain went on alert when he said he chose 227 as setting to get within the spec of 225 - 250. I am paying attention to these videos because they are fascinating and because I don't have a lot of hands-on experience, so I wanted to know why. I thought he said he accidentally went to far torquing one, and it hit 240. I thought that was the reason, but he did not state (from what I remember). Anyway, thanks. I will never work on a jet engine, but I was always fascinated and the cut-away drawings and cut-away engines I saw never quite explained it to me. I was disappointed that I did not see it spinning on the balancing machine. I have always wondered how high-speed balancing works.
Well, we have decided that next time I balance something, I will show the running of the machine. A word of warning: the machine is computerized, and the operating system is Win95. I shit you not, sir!
ppl saying you use cheap tools.....................im no jet engine master but common sense tells me if you were doing such a bad job or didnt have quality standards you wouldnt be succeeding in any way, theres no room for sub par standards with these engines and if you really screw up once you could lose the business altogether, its not acceptable in this field, no second chances sometimes
Your comment is both a weather vane and the tip of the iceberg. All previous balancing videos have brought on a torrent of nothing but complaints about the process, or advice how to do it, or complaints about how I don't know what I'm doing. ... not interested, and hey, it's my show...
You need to be something like a mechanical genius to do really well. That is something you are prepared for early in childhood and possibly in the womb. None of that requires a formal education. It's like writing, either you have the ability or you don't.
Wish I had money to buy even just one helicopter engine then build a pulling tractor around it. Heck I wish also that I could afford a pair of GE F110 engines for you to play with on the stands but then they would just be sitting an collecting dust after that. If only I could have a F14D to put them in lol.
A hundred years ago, millions of soldiers died in the mud; most of them were 18 years old or even younger. I think of that and realize how lucky I am to live where, when, and how I do.
I wore my poppy on Remembrance Sunday too. My maternal grandfather survived the Great War, having been wounded twice: if he had not, then I wouldn't be here. A few years ago, I visited the locality in Flanders where he saw action and paid my respects at the Menin Gate in Ypres to those who did not return. I also paid my respects at the village war memorial last Sunday, with gratitude that my son returned safely from Afghanistan, remembering that he lost two friends from his regiment there. To complete the record, my paternal grandfather also served in and survived the Great War. However, I know very little about him, other than he was a driver, having been one of the first chauffeurs in the country before the war. I believe that he was gassed and had a lung removed as a result.
Didn't see a link in the description so here's a link to the videos section of Darren's page, just remove this comment or thumbs down if either party didn't want to link these videos. ua-cam.com/users/DScottDuncanvideos
Are you seriously trying to hold that wheel sitting on those bits of wood while aplying 250lbs ?? what is it you actually do in that outfit follow the brush around..
Are you seriously expecting me to take you seriously when you don't know the difference between inch pounds and foot pounds? Double punctuation indicates fear, confusion and panic. Calm down, please.
Hi Jay; thanks for featuring my J44 in one of your videos! I am honored. Let us hope that I can get it all back together and running once again, restoring and helping to preserve a small piece of the history of gas turbine engines. It is a fairly simple engine , disposable, if you will, so that is a good start for us moronic beginners. The compressor is a mixed flow type, with 'impeller' and a 'compressor' pieces mated together. The two parts are actually two different metals; impeller is aluminum and the compressor is magnesium. Those turbine blades are actually welded to the disc! That is hard to believe but if you look close, you can see the two different-looking metals where they join together. Mark pointed that out, otherwise, I assumed that the 'blisk' is one piece as manufactured! The last version, the 'flight rated' J44-R-3, used the individual blade design, with a rotor disc, replaceable blades and keepers.
All of my aluminum 'test stand' was designed and built by Mark of BoMar Industries, as well as that shipping package. Those boards were cut from a 4' x 8' sheet on a Mazak laser cutting machine! He is a friend that likes to trade favors so I have his talent and vast shop to help me out at times. Thank you to Mark for his time and efforts on the J44 Project. He made the stand itself, the engine mounts (Soon to be modified so that the rear mounts will slide axially, to allow for thermal expansion, per Jay's recommendation!) and the ignition exciter unit mounting bracket. Oh and the special spanner socket to fit the compressor stub shaft nut. Fragment sentence; sorry Graham.
Last but not least, thank you Jay for taking the time to mess with my pissy little project, just a hobby for me, in your real world of gas turbine engines! Many jet shops would not want to bother with such a job. Thanks for your services and I intend to video everything; reassembly, checking clearances, reinstalling it on the stand, then, finally, firing her up! I am shooting for sometime next Spring.
If you watch my "J44 3rd & 4th Runs!" video, it has a different set of sound characteristics, due to the GoPro cam being in its water tight case. The 'louder' jet sounds (high velocity gases rushing) are muffled enough to allow us to hear those sounds traveling through the stand and to the camera through its mounting (it is mounted on the stand cross-brace in the center, facing towards the rear (exhaust) end. Besides the fuel pump noise, heard at first, you can hear 'shaft' or 'gear' type noises that change with the speed of the shaft, up to idle speed. There would be some gear noise from the accessory drive box but some of that noise could be from an imbalance. It will interesting to use the same camera location and video a run, then compare the sounds! I am gonna bet it will be 'quieter'!
I had a shot of moonshine (bought in a store, legal, some 'Tim Smith's'!) a while back when you told me you had the rotor balanced! To me, it is 'Voo Doo', the art of balancing an assembly! A disc I understand but an assembly, no. Thanks again and cheers!
DD
Very cool channel! I'm studying for my aircraft technician license, and a teacher showed us one of you videos on jet engine bearings. Educational stuff, keep up the good work!
I've had the turbine bug since the summer of 1999! I went on a trip with EAA explorers to Denver CO to visit various aerospace manufacturers, I was into electronics, computers already at that point, when I got the first sight of the engineering beauty of the first commercial turbines I was able to examine closely, I remember it was at the old Denver international airport not long after they opened the then newer Denver intl. airport. When I returned home, I started on a turbine project, I quickly figured out from a then few other turbocharger based gas turbines, that I would build a turbocharger based turbine with a T3 turbocharger. I was able to purchase two junkyard T3's from donor cars, I believe they were both '80s 4cyl dodges, first I quickly figured out from a local retired Boeing engineer that I needed to work on the combustor first, back then the info. on these type of projects was scarce compared to today. I built a combustion chamber carefully over the fall into the spring of 2000, I tested several designs with a chamber - case made of a high nickel stainless, it was 1mm thick and welded by a local welder that did a superb job! I tested using an electric leaf blower and carefully placed thermocouples. I purchased rebuild kit for one of the T3's. with beryllium alloy bearings and new balanced compressor, and tested with the rebuilt T3, the rebuild kit was around $200 then, today you can get an entire T3 for $200, I did purchase a new T3 kit springtime of 2000, it cost over $600 then, with a ceramic bearings (zirconium oxide) kit, a $200 additional cost, which then ceramic bearings were a new 'premium' feature. By May 2000 it had its first run, now was time to build a controller, which then there weren't the easy to deal with arduinos or like hobby control boards that a plentiful today, at the time the Microchip PIC16F84 was a good choice, it is a microcontroller that is flash re-programmable, used to time & control everything for start-up, idling, throttle input etc..., I wire wrapped the control board, instead of acid etching test perfboard(s), which I later produced a finalized control board this way, It hasn't been installed permanently into the final setup. The complete turbine in its final current example, which I still own, was started around Jul 2000, and is still setup to run on propane, it still runs, as I am asked to bring it to the local vocational school fair once or twice a year, I still know the teacher at the high school, he will request me to show it a few times a year as well. The only things I've added to this turbine is, I've built an additional swap-able exhaust nozzle, one with chevrons & one without, and will run them one after the other to show how chevrons reduce exhaust noise, as well as a different intake with an acoustic tube, also to demonstrate noise reduction.
Mooted: That this young man be proposed for an Honorary Degree.
For services above and beyond the norm. For exceptional educational value. For dedication to clarity of understanding.
The quality of the shipping crate is beyond my level.
love the vids u have on here, Im one of two rotor techs in the company i work in in england, we inspect , strip and build and low speed balance Seimans TA 1750 ,Tornado ( sgt 200 ) typhoon ( sgt 100 ) tempest ( sgt 300 ) compressors with the HP/LP discs , love the challanges of building and balances these girls ,Would love to aspend time with u guys ,
Must say I was wincing when I've seen the whole (well, half of :) ) rotor assembly resting on the turbine blades. As I have no doubt you know your stuff this is news to me: turbine blades/blisk are much stronger then I would have guessed just by looking at it! :)
Thank you very much for all the videos you made. My four flights on jet airplanes at the end of october were much more fun after seeing all your videos and knowing what's going on engine-wise!
The table is covered in rubber, so everybody is happy.
As I've said elsewhere, for those concerned about two blades taking the weight of that end of the rotor when it was on the table: don't be. The two were each only just off the vertical and were acting as struts in compression. Using a pair of Mk.1 eyeballs, calibrated with some experience, I reckon they would have been more than strong enough .
Nevertheless, I couldn't resist doing a few very rough calcs, which I won't go through here, but I reckon that the gas bending load on each blade will be at least 50lb and probably a good deal more. I wouldn't recommend it, but I reckon that, if AgentJay Z lifted the rotor off the table with an attachment at the impeller end, plus a pair of strops around the two blades on the horizontal centre line of the turbine disc, then they would take the load quite comfortably ..... probably.
Ah, life is good once again. Nothing beats watching the master work his craft. Hope the beard comes off soon. having a home with workers in it all the time can get very, very tedious.
You can put a little Sharpie marker dot next to the nuts you have torqued, using multiple colors for multiple passes. Though a visual inspection for preexisting marks and mark-like marks would be necessary. They often do it on bike for "safety" fasteners.
[I remember when my brother left a bolt loose on a car-engine flywheel, and the ticking sound it made as it tapped the clutch fingers.]
Cool engine! I don't recall you doing any vids on centrifugal engines before.
Nice touch wearing a poppy much respect
Man, you have so many cool tools and parts, and are having so much fun. And don't be skipping screws; it's like the sound of screechy chalk on a blackboard.
Jay, LOVE your videos. I'm an Agent JayZ junkie!
It would be really cool to, someday, actually see that
dynamic balancing process.
Biff, in Arizona
I don't know the "cost" of the Rolls Royce and Orenda wall plaques, but it took $6million for me to get a Solar jacket some years ago. They used to have some really nice jackets with a picture of a turbine embroidered in the back in color. I was told they only gave them out to Solar employees. The company I worked for at the time purchased 3 Taurus 70's for a power project. So I got my jacket!
Wanted to see the balancing operation :(
i am also doing balancing... and so many turbo charger i am doing balancing.. now i learn some more thinks... thanks for sharing this video
Oof, that assembly is beautiful! As part of Phase Two of my project, I've been looking at upsizing a 7" compressor with various modeling methods to see if I can build one out of carbon fiber. Trying to find a compressor wheel that size in my 'budget' was getting to be a problem, but I look at this with envy! It's soooo big!!
Wow, the disk and blades are 1 piece. I don't even want to think of the amount of machining and finishing work that has to go into that during manufacture.
The ultimate youtube unboxing video.
Can you show us the balancing process? I'm interested in how the balancing machine works. Thanks for all your videos.
Maybe next time.
I've done only newer two spool high bypass turbofan engines mainly, which are usually balanced in many phases. Static balancing for disks and dynamic balancing for the whole assembly/stacked rotors/seperate spools. Blade positions are calculated by their moment weight for disks which needs it. One can shift the blade positions or add weights. Usually after grinding it is not allowed to shift blade positions anymore, and that's why most of the rotors are pre balanced before grinding. The machine shows unbalance or needed correction or whatever you have chosen it to show in weight and degrees in planes what you are balancing. Or at least the schenck machines do. Tolerances are given in various units like gram-inch, gram-millimeter. In test run some trim weights are added to the fan if needed.
I remember reading somewhere that the blisk versions of this motor were dangerous and they went to a conventional turbine wheel. Maybe the blisk versions were one time use like in a missile or target drone.
I was hoping to see the actual process of balancing the spool. For example; the speed at which the balance takes place and the calculations required as it is not at operating speeds.
I am curious , do you confirm the balance after the final torque?
I was suprised to see the assembly resting on the table unsupported.
Thanks
It's an extremely robust assembly. It performs it's job at over 10 thousand rpm and while nearly red hot.
Realy beautiful machine uff i like this turbine design
.....And you're more than books. Hats off for you
Whats your opinion on that Boeing 767 American Airline that caught on fire last October. They said a turbine disc failed. Don't they checked those discs for cracks during schedule inspections?
Of course they do. However, if you had checked the NTSB website, you would have found a photo of the failed HP2 turbine disc sections and a preliminary determination that fatigue propagation had initiated from an internal defect. Such defects are by no means impossible to detect using the latest NDT techniques, but it would be a good deal more difficult. I'm not in a position to draw any conclusions or speculate as to why the original defect was not detected, nor why a crack wasn't detected in its early stages: I will leave that to the NTSB.
Fortunately, such uncontained failures occur only very occasionally, but they do happen. We had an uncontained failure of an HP compressor disc in the engine of a BA B.777 at Las Vegas last year and, back in 1989, a fan disc failure that led to that crash landing at Sioux City. Years ago, R-R had several failures of both fan and HPT discs in early RB211s, but no aircraft were lost. The experience and investigations contributed directly towards improvements in both metallurgy and inspection techniques.
Good video thanks. At about 7:45, was that a bit of chewing gum or special putty on the back of the compressor disk, using it to mark where to cut-out?
Having spent time on smaller gas turbine engines, the turbojet kind that spins in excess of 40.000 RPM, this looks like a test weight. You can see that the cutout made to the compressor`s back side is 180 out of phase with this test weight: you measure the weight of this material, and subtract from the other side. This is a lengthy process as balancing must be done in smaller and smaller adjustments: you dont want to cut more than necessary. Also, notice how the cut is done as smoothly as possible to minimize the risk of metal fatigue. I am not sure if +AgentJayZ put it there, or if it was left as a starting point by the engine owner. Either way, it seems that it was close enough in placement, but quite smaller than necessary. When we worked on balancing, we used a rubbery adhesive (like gum) used in car body shops
thanks for taking the time to answer. very interesting about the 180 out of phase. makes sense.
I love your videos body .
Well explained and thanks for share your knowledge .
I am learning alot to do my own project .
👍✈
Wow that fuel pump looks so close to a Stanadyne Diesel Injection pump. Prolly a little more skookum though
If a blade of that, as its called blisk, goes your done and had to by a whole new/used disc?
Cool video! But what is the point in those little holes on the blisk on the base of the blades that don't really look like they take out any heat?
They will be to create a defined pivot point for the blades to flex about as they heat up and expand. If the expansion slot is taken up and any pressure applied to the adjacent blade, the metal will happily flex about the lower pivot point.
Can you explain the reason for the complicated transition from the disc proper into the blades?
In particular why there is that strange ridge on the blades that looks like it is joining them into another ring part way out? Does the air from the inner and outer part take a different route through the rest of the engine?
1- it has to be strong enough so the blades don't rip out under centripetal stress.
2- larger blades in older designs needed those points of contact with each other for support and prevention of vibration and oscillation.
3- in turbofans, yes. That's why it's called bypass air.
thats awesome could make a similar engine from a locomotive turbo or even a large ship turbo but especially an EMD turbo because it has a power takeoff from the hot section
Turbochargers are power adders for piston engines, and therefore can be considered slaves. Turbojets, even small ones, are complete engines on their own, and are free to propel small aircraft to speeds several hundred miles per hour.
so tnx for yor videos.you are best👍
Which Material For Turbine Blade Sir.
very cool. im surprised its ok to set the blisk on the blades like that.
They are each under hundreds of pounds of force during operation. This is nothing for them.
You mentioned some repairs were done / blades swapped. How does that work on a solid disc?
... that was before I knew it was a blisk. Just another example of me not knowing what the heck...
So in this config if a blade gets badly damaged you are good to buy a hole new blisk ? .... Same question for resonance I know they it's a working design so it's not a problem, but isn't the hole turbine and compressor blade not attached to the main frame to avoid resonance ?
I'll jump in and tell you what either Darren D or AgentJayZ could tell you. The J44 was originally designed as an expendable engine for a drone application, so it was never intended to come back for repair and overhaul: if it did, it wasn't intended to last very long, so R&O was not an issue. However, as Darren D has pointed out, the engine was further developed to a "flight rated" standard - as was the dear old Viper, which also started life as an expendable engine and with which I am more familiar. Back in the 90s, we even had to 'convert' a 202 engine out of a Jet Provost into a 201, to go into a Jindivik - if you don't know what those aircraft are, try Wikipedia.
I'm quite impressed by the the blisk design and manufacture of the J44, recognising that it would have been quite possible, but probably far more expensive, to machine the aerofoils from a solid disc. However, in those days, long before CNC, it would have meant a very laborious copy-milling process and a lot of work by a skilled blade polisher (or two). I saw some of that on much smaller turbines for helicopter engines when I was an apprentice way back in the 60s.
If you're thinking in terms of a firtree root being necessary to provide some damping, well think again. There might be a small effect and you can certainly kid yourself when the blades clatter loose as the engine is running down. However, think in terms of up to 50,000G at the rim of a disc and how rigid a firtree root will be under that sort of load.
And for those concerned about two blades taking the weight of that end of the rotor when it was on the table: don't be. The two were each only just off the vertical and would have been more than strong enough.
PS I couldn't resist doing a quick calc for that disc: its rim G loading will be about 30,000. The 50,000 I quoted would be more typical of an HP turbine in a modern engine.
is he resting the assembly right on the fan blades !? :|
Question dealt with below. There is no fan in this video.
yes and they were flexing as he torqued the nuts, is he nuts?
And is onenut done up 13 more than the others?
How does a BLISC achieve vibration damping, since blades are not free to move ?
Blisk technology is used on smaller engines, where the natural resonant frequencies of the blades are outside the range of excitation experienced during operation.
Thanks.
Hi Jay - Regarding the J79 afterburner actuator - How much force does a single one produce ? The J79 appears to use four of them.
Not sure, because it's not stated anywhere. But they have a piston diameter of about 2 inches, and are supplied with fuel at around 600 psi...
It still boggles my mind that these things run at such slow speeds! 10k RPM? Really says something about these large compressors efficiency, when my little Holset Hx40 needs to spin at 240k RPM to make boost! Friggin Incredible!
The speed of the blade tips is the important thing, this one's rated upto 15kRPM I think, and has a radius of about 10" (0.25m), which means the tips
go about 375m/s, or faster than sound (in cold air, but the air will be hot so it won't actually be supersonic). A small turbine does more RPM to get to the same blade speed. A turbojet engine has to stay subsonic in the core (otherwise you'd have a scramjet!).
How is the shop kitty doing?
Like all good things, there must come an end. Shop Kitty had a long and luxurious run, and has moved on to a higher ground.
AgentJayZ R.I.P. Shop kitty :/ I hope there are a job opening for a Mk II, I suggest a Norwegian Wood cat ( skogskatt ) because they are social,friendly and have no inbred health issues. They can get up to 18 years or older.
Hell, if we're making Shop-Kitty recommendations, I'll vouch for this gray thing I rescued from the animal shelter that looks like it has a lot of "Russian Blue" in it's genetic background. Super friendly and confident cat.
Godspeed Shop-Kitty I
I watched the whole video and I still have no idea how do you figure out the balance of the assembly.
He spins it on that special machine which feels what way it's pulling while it's spinning to figure out which side is heavy
Same way they balance tires, pretty much.
The balance machine sensors are connected to a computer, which makes suggestions about where to add or remove weight.
Is there any particular advantage to a bladed disk / blisk over a turbine wheel which has individual blades fitted by those "fir tree" slots around the circumference? I suppose the blisk can be manufactured in one piece, but until I saw this video I didn't know they were made that large. I knew that smaller engines (like helicopter gas turbine engines) use blisks for their compressors and maybe for the turbines as well. Anyway, what happens if one of the blades gets damaged - do you have to replace the whole blisk? I'm guessing you can't just cut the damaged one out and weld a new one in, because the welded join would be weaker than the rest of the metal. Plus it would throw the balance out and probably cause many other problems.....
I believe the blisk was invented because a government contract for a new military engine was attempting to reduce costs. The specification was for a reduced parts count.
Manufacturer says "Yes, sir! A 30% reduction in parts count!".
Only thing is, it was more expensive anyway, and as you pointed out, repairs weren't cheaper either.
You damage one blade in a blisk... the whole thing needs to be replaced.
Fair enough. I bet there were some questions asked and a lot of office stationery thrown around when the manufacturer submitted the final bill - and the civil servants thought "OK, they have reduced the parts count as we asked them to, but it's now more expensive? And what's this - we can't repair that large, expensive and rather vital component? We have to replace the whole thing instead?"
I wonder if that's where Apple got their "no, you can't repair or upgrade your iphone / ipod / macbook in any way, you have to buy a new one" inspirational ideas from?
On civil aero's ie Trent XWB high pressure compressor it's for mostly for weight saving. FOD damage is a proper PITA necessitating being build up by welding and subsequently adaptively milled to recreate the aerofoil. You wouldn't design it like this for with no good reason. Although I'm not a mechanical integrity engineer I imagine the stresses would be lower in a RR style blisk as the root fixation stresses can be very high and not having discontinuities in the rim ie blade slots will also help - this doesn't apply to this arrangement. I'm not familiar with this engine but I suspect as it appears to be a turbine blisk it needs the expansion slots ...... A rough rule of thumb was that for every unit of mass at the disc rim necessitated double to be applied to the disc 'cob' or bore to contain the stresses.
I have a question about Axial compressors.
You know how the compression happens when the fast air enter an expansion section of the jet-turbine? Does that mean that the air does not take up the entire space?
If it takes the entire space and compresses by loosing speed, then there's a loss of energy for the expansion no?
I hesitate to answer, because I don't want to discourage your search for knowledge, but I have no idea what you are saying here.
None of it makes any sense to me, and I'm not going to try and guess what you mean.
As always, I suggest the first chapter or two of an introductory text on gas turbine engines.
You'll see them often in my playlist "Your Questions Answered".
So you don't do the final torquing on the balance machine?
Balance doesn't change at all once she's all tightened up?
Not a jet mechanic, but pretty sure balance only depends on weight, it's not going to change as you tighten the nuts (unless you overtighten them so much it bends the thing).
The balance heads are delicate, and not a good place to have the shaft when applying forces to it.
AgentJayZ Fair enough.
***** Yeah, I was thinking more of the elasticity of the metal. Hooks law/Young's modulus ect. I guess it's just insignificant.
Congrats on that badge! Obviously your job (and your co-workers´) is a big part of it being hanging there!
From an R and D aspect: once balanced, installed and tested in the engine If you ever had to re-check the balance AFTER a test run, would you still find that turbine perfectly balanced or would you anticipate a bit of adjustment.
Interesting question... I feel like I am playing 3D chess with Spock.
Why would I need to recheck the turbine balance after a test run?
Because the vibes were too high.
I would of course expect the turbine to be out of balance, because that's what makes an engine shake...
...
... ...
eh?
I have had vibe issues with a bad batch of rear bearings and with coupling nut issues , its rare but it has happened . re-clocking of the turbine during installation has also been effective. What brought me to that question was that both Shenk and Hoffman balance machine reps have both indicated that some adjustment would be needed to balance the turbine simply by just removing the turbine off the balance machine and re-checking. Their answers bother me , lol. thanks though.
,,, how could you Not show the assembly spinning in the balance machine ??????
What’s the point of that green strip in the middle?
I doesn't really have a point... in more ways than one. It can serve as a border between the front and the back, in case anyone gets lost.
@@AgentJayZ we are tearing apart these j44s in class , instructor just informed us that green stripe is for heat detection, so if the shaft overheats the green turns into a orange or darker color and basically disintegrates. Neat I guess
I guess, but to know the engine is overheating, you have to disassemble it? Plus, the shaft is very well protected and isolated from the actual heat of the gas path.
You can tell your instructor that I think he's pulling your leg... or maybe someone is pulling his leg.
I'm not buying his explanation, but if he wants to reference a source...
It can’t have no reason for being there at all, if there was no reason there would be no green stripe. The look of it is way to specific for it to not have a function. #questioneverything
@@AgentJayZ I think the entire point is once you disassemble it, you will know once you see it, we can physically see as some of the ones that were green, are less green, some strips are orange/ dark red and some black and almost completely gone. So it seems to support his idea we’ve got about 6 of them disassembled in our hangar right now. I’ll check with him tomorrow and ask again. The manual doesn’t have anything about it but it doesn’t have much of anything I guess since it was written 10000 years ago lol.
So if one blade would break you had to buy a whole new disc with blades on it then? That kinda suck.
are jet engine like big flywheels is that were they get such high horse power ratings?
No. They are powerful for their size because of their ability to burn a lot of fuel. There is a large rotating assembly with considerable mass to it, but when fuel flow is reduced or cut off, the deceleration of that assembly is instant.
thank you
I noticed that the end of the shaft on the hot side was damaged post balancing. It was not damaged pre balance. On your balance rig I see a small bearing on the hot end which I guess is used to keep the shaft from moving fore and aft. Did that small bearing get into the end of the shaft?
So, let's get this straight. You are saying that in the process of balancing this rotor, I damaged it?
Based on what you saw, but are unwilling to refer to as a time in the VIDEO that you have just watched on UA-cam.
Is that what you are claiming?
I just want to be clear on this.
The points of life get cheaper every time you get another point until you buy a new bit, lol
Nice videos man. We jus finished to disassemble ALSTOM GT26 FOR COMPRESSOR BLADE REPLACEMENT. ITS A LITEL BIT BIGGER ;)
i cant even fathom the ability to learn what you have with these engines, you can break it down and im like WTF i still dont get it and then feeling of being an idiot sets in !
i love the snap-on shine XD
wow a blisk for a turbine disc? I assume the whole thing is dipped in fluorescent dye to check for cracks after manufacturing? whats that blisk made from? ti?
No, a turbine disc wouldn't be in Titanium, then or now. When the J44 was designed, I doubt that Ti was available and, even if it was, it would have been too expensive for a short-life expendable engine. I think that AgentJayZ has already suggested that the disc may be steel and the blades may be Nickel-based. However, in an engine of that vintage the blades could well be a heat-resistant stainless steel, particularly as the engine was destined for a short life.
it sorta has a stainless or Ni-Fe luster It seema like it would be much more difficult to manufacture that way compared to christmas tree rooted blades.
Fir tree blade roots and disc slots have to be manufactured to very tight tolerances (to within a couple of tenths - of a thousandth of an inch), so that the serrations share the load reasonably uniformly. Very specialised high precision machine tools are, therefore, required. An established jet engine manufacturer with such equipment would, no doubt, have utilised it to make discs and blades for an expendable engine. Armstrong Siddeley did when they designed and built the first Viper. However, Fairchild were primarily aircraft manufacturers and would almost certainly not have had such equipment. Assuming that constraint, the design and manufacturing solution that they came up with was (in my opinion) eminently fit for purpose.
I note that your shop is as quiet as a church library. There was definitely no "While My Guitar Gently..." in the background.
sir..is it started by motor ?
Can you please show a GE 747 turbofan engine ?
The 747 is not an engine, it is an aircraft.
I do have a video where I do a quick walk around a JT9-D, which was the first type of engine used in the first generation of the 747.
10:42 it's either that or a dlade
I want to Punch the guy in the face that invented the Try-wing screw XD
I only just watched this video, from obviously a while back, but I simply wanted to ask, are you susceptible to flooding where you are, and is the snow melting earlier in the season? Just makin comparisons, as I have a friend that lives up north somwhere.
At what RPM does your balancer run while balancing?
Whatever speed you choose, depending on the diameter of the driven piece, and speed control setting.
6 inches and 3/10 makes about 500 rpm.
отличный канал и работа
That is a moving little unit!!!! 15k?
I hope I have not offended you. As a mechanic I know that no matter how careful I am, $hit happens. To me the shaft at the 7:55 mark looks a bit different that at the 10:15 mark. Perhaps I'm mistaken.
There you go. A time stamp is very helpful. It looks to me that the turbine disk was balanced by grinding away at an area supplied for just that.
It does look like scarring.
The marks on the turbine are visible at both of your time stamps, but the lighting was different. Being a tech yourself, I expect you to notice all details with an eagle eye.
My goal was to balance the thing without any grinding. I managed to do that on the turbine, but the only way to balance the compressor was to grind, so I did.
All of this was explained in the video.
Did you watch all of it?
Hell yeah you offended me. If you are gonna say I damaged something, you better be damned sure, not just guessing.
There's no replacement for actually being there.
It is the same before and after balancing. I guess you were confused because the shaft was not at the exact same angular position after balancing, and you could see some marks on the hot end turbine at 10:15, which were not visible due to the camera angle on the turbine at 7:55. You can see the same marks at 7:55 too if you look a little bit closer to the far side of the turbine. And I am assuming those marks were scraped off for balancing the turbine in the first place anyway...
Johann Sebastian Bach
Thanks for your explanation. I agree. It was camera angle. I didn't notice the countersunk portion on the end of the shaft in the first time stamp shot. That is what I was asking about but when things were getting tense I dropped it. lol.
Yeah, I can understand that. Both you and AgentJayZ are relatively young and quick-tempered, whereas I am 331 and chill :D
Sorry, nitpicking warning as nitpicking coming up:. Strictly from a Metrology point of view, it is unlikely that your torque wrench has better than combined 1% accuracy so it is possible that setting your torque wrench at 227 could end up being a slightly below the specification requirement of 225 to 250.
+Jack Feder
Meh.
Sorry, I only heard where he set them to 227. My brain went on alert when he said he chose 227 as setting to get within the spec of 225 - 250. I am paying attention to these videos because they are fascinating and because I don't have a lot of hands-on experience, so I wanted to know why. I thought he said he accidentally went to far torquing one, and it hit 240. I thought that was the reason, but he did not state (from what I remember). Anyway, thanks. I will never work on a jet engine, but I was always fascinated and the cut-away drawings and cut-away engines I saw never quite explained it to me.
I was disappointed that I did not see it spinning on the balancing machine. I have always wondered how high-speed balancing works.
a friend of mine has a MiG 23 jet engine in a basement :)
or was it 21, can't tell
If you really want to go high-end for a torque wrench it should be a Tohnichi.
I would like seen that ran in balance machine I never ever seen something other then tires in balance machine
Well, we have decided that next time I balance something, I will show the running of the machine.
A word of warning: the machine is computerized, and the operating system is Win95. I shit you not, sir!
AgentJayZ I shit _you_ not, Mr. Jay 😊
ppl saying you use cheap tools.....................im no jet engine master but common sense tells me if you were doing such a bad job or didnt have quality standards you wouldnt be succeeding in any way, theres no room for sub par standards with these engines and if you really screw up once you could lose the business altogether, its not acceptable in this field, no second chances sometimes
Three people voted this video down? Unbelievable
I see more than just jet porn in the opening. Splendid!
You could have shown 10 minutes of how the balancing machine works.
Your comment is both a weather vane and the tip of the iceberg. All previous balancing videos have brought on a torrent of nothing but complaints about the process, or advice how to do it, or complaints about how I don't know what I'm doing.
... not interested, and hey, it's my show...
What kind of education do you need to do this kind of a job?
You need to be something like a mechanical genius to do really well. That is something you are prepared for early in childhood and possibly in the womb. None of that requires a formal education. It's like writing, either you have the ability or you don't.
Use Torx and you regain life points =D
You call it a compressor blade, I call it a kaiser blade mmmhmmm
Wish I had money to buy even just one helicopter engine then build a pulling tractor around it. Heck I wish also that I could afford a pair of GE F110 engines for you to play with on the stands but then they would just be sitting an collecting dust after that. If only I could have a F14D to put them in lol.
I'm going to start wearing a poppy on what Americans (improperly, IMHO) call veteran's day.
A hundred years ago, millions of soldiers died in the mud; most of them were 18 years old or even younger.
I think of that and realize how lucky I am to live where, when, and how I do.
I wore my poppy on Remembrance Sunday too. My maternal grandfather survived the Great War, having been wounded twice: if he had not, then I wouldn't be here. A few years ago, I visited the locality in Flanders where he saw action and paid my respects at the Menin Gate in Ypres to those who did not return. I also paid my respects at the village war memorial last Sunday, with gratitude that my son returned safely from Afghanistan, remembering that he lost two friends from his regiment there.
To complete the record, my paternal grandfather also served in and survived the Great War. However, I know very little about him, other than he was a driver, having been one of the first chauffeurs in the country before the war. I believe that he was gassed and had a lung removed as a result.
Keep the beard! it suits you.
if you want to help or personnel i can help i am balance and hsg operator. i have full balance and grind authorization for v2500 cfm56 3-5-7 soon cf6
Awesome jet porn!! Hope my mom dont find out!!!!
Didn't see a link in the description so here's a link to the videos section of Darren's page, just remove this comment or thumbs down if either party didn't want to link these videos.
ua-cam.com/users/DScottDuncanvideos
I didn't put a link in only because if you do as suggested, and type J44 in the YT search bar, Darren's videos are right there.
Gotcha 👍
Are you seriously trying to hold that wheel sitting on those bits of wood while aplying 250lbs ?? what is it you actually do in that outfit follow the brush around..
Are you seriously expecting me to take you seriously when you don't know the difference between inch pounds and foot pounds?
Double punctuation indicates fear, confusion and panic.
Calm down, please.