I've been shooting my entire adult life, and I'm older, and I now know more about bullet aerodynamics and ballistics - in general - than I ever did. Thank you, Sir.
@@19Borneo67 Also the the extended 'boat tails', on the race cars at LaMans in the '70s. I was closely watching the NASA research on drag reduction on semi trucks, also in the mid '70s, I believe. The further they extended the faring out past the flat rear of the trailer the more aerodynamically efficient the vehicle became.
In the research you will notice that boattails dont do much at subsonic velocities (yet everyone mistakenly wants a boattail for its supposed improved lower drag). However, if you check the data, you'll see that a heel or gas check rebated base (without the gas check) has a very good a drag reduction at subsonic compared to a flat base projectile. There's some other advantages to a healed bullet and that is when a boattail is exiting the muzzle the gas jetting around the boatail tends to knock the tail off to rhe side slightly and so the bullet base 'spirals' or hunts for the first 50 to 100 yards before settling down. The crown of the muzzle is critical to launching a projectile smoothly. A flat base bullet exiting a cocked muzzle will get a jet on one side first and be knocked off quite a bit too BUT the healed bullet is affected least by this. I shoot bigger bore cast bullets, very long range and subsonic only, not 22LR and I've gone pretty much all healed designs (ordered as gas check molds but no gas check is ever used). I'm not ordering stock molds, im having my own custom designs done (ie: at Accurate Molds and even 4 of my designs at NOE Molds). Note that boattails are especially poor dropping down into subsonic at extreme ranges which is a problem the military has delt with for years with it ELR sniper rounds, the further down range around trans-sonic, the MOA jumps up a lot. And further, ive found that a flat meplat of 62% to 70% projectile diameter has a better Drag Coefficient than a rounded or pointed nose as you indicated in your video. The nice thing is that a hollow point loads up with air and becones the same drag as a solid flat meplat, so i use a HP aa necessary to adjust the CG of the bullet and move it aft (and some of them are good hunting rounds too, search for NOE mold # 358-152-HP-CF4 but shot without the gas check. Shot at 950 FPS its not lubed but the grooves give reduced bore friction, but the contact length gives it good internal ballistic stability (not cocking in the bore like a lot of shorter bullets) and a fair length for external ballistics (of course the ideal is 6:1 but in this caliber for subsonic flight only it gets shortened). The mentioned projectile, shot subsonic, gets MOA at 500 yards so I'm pretty proud of it.
@@jamesconger8509 I'd note that I might cast 200 bullets but by the time I QC them and eliminate any with weight variations (they all have to be visually perfect but MUST weigh within 0.01 grains) I get around 30 match grade slugs. And I consider myself an expert caster and have probably cast around 15,000 to 16,000 bullets (and shot them too!). I HAVE to shoot into bullet traps because I need to recycle the lead to save money. I have a range on my own property with 25, 50, 85 and 100 yard target stands (and a trap behind each) Why 85 yards? Because at 950 FPS, an 85 yard zero gives +-3" high at 50 yards and +-3" low at 100 yards. All my subsonic rifles are zeroed at 85 so I can swap from rifle to rifle and all hit the same point of aim. And I hunt a lot of hogs all year round, it simplifies drop calculations when aiming if you don't know the exact yards.
You rock. That explains why my Accurate Mold for .447 concicals with a gas check shoots so damned well in my cap and ball guns. It's point of aim up to 25 yards with 30 grains of Swiss. My friends were impressed whch ish ard to do .
Excellent balance between being clear and being absolutely technically accurate. I didn’t hear anything that you said that was “wrong” and you didn’t get lost in the weeds. As an ex-CFD guy, I would tend to get overly detailed and caveated for my audience (management) in an effort to be totally transparent. They just got bored or confused, or both. I did that because I learned the hard way that Box’s quote, “All models are wrong, but some are useful.” is really true. CFD can be a very useful tool, but it isn’t Truth. Some people take the simulation outputs as Gospel and don’t run them through the BS-o-meter, which can bite you. I am interested in OpenFOAM now to see what it is as I am now retired and don’t have access to the industrial codes any more. Thanks for an excellent presentation of your work!
@andrewhahn1476 Thanks, and thanks for reminding me of that great quote. One thing I have found throughout my career is that building models is a key to understanding a subject. Once you get that understanding, it is best to throw the model away.
The G/1 model was first developed for artillery back in the first world war where they were predicting the trajectory of hundred pound artillery shells. They were all flat base and short nosed. It’s kind of a holdover. And because it has the highest number, manufactures will not give it up. 17:35
Yeah, unfortunately, it's often the only apples to apples comparison. Before the G7 came out, it was THE bullet BC . Of the people who cared about BC and out of the companies that published it back then, the oversimplification was more higher BC = more better bullet. This was before the internet, so mass education on complex subjects wasn't really a thing. Basically a marketing holdover, although some classic bullet designs still fit the model. I think it was Krup munitions company that came out with G1, might be wrong though. Now "custom drag curves" are putting G7 out of business, though manufacturers will probably never stop reporting G1 and/or G7.
I was about to post something similar, except that I believe G1 model dates back to the late Victorian era around the advent of smokeless powder for artillery. It is NOT a model suitable for small arms ballistics except in the subsonic regime, as I understand it, but my knowledge is admittedly limited.
@@nunyabidniz2868 Yeah I vaguely recall that timeline too. Without looking, I don't know for sure when. I'm fairly certain it was Krup munitions that came up with it, but that might be incorrect too. Definitely appeared somewhere between 1850 and 1918 after the popularization of conical projectiles. It applies to small arms and arty, it's just not as accurate as we'd like, but better than nothing. This was a time when sub moa groups weren't really a thing, even in competition circles. I'm sure it happened, but wasn't the norm. 3 to 6 moa was fairly standard for precision. I'm sure arty has changed in a similar way. So in those cases, a "close enough" model is "good enough".
The G1 does match most 22lr bullets closer than G7 though. It's the only time I'd consider using G1. Thankfully there are lots of bullet specific custom profiles out there now
Thanks. I appreciate the informative data and sharing what you learned. The influence of its CG to be less resistant to tumbling down range was insightful. One of those things that makes sense but I never thought about. I’ve always wondered how much rifling grooves impacts the flow around it but for larger projectiles amongst other things. Anyways thanks.
Very well done... and the best thing, besides seeing that the bullet shapes are already optimized, was seeing that the increase in the barrel reduced the speed of the bullet, making the 16" long one better ... ! 😮❤
I have noticed that most subsonic rifle bullets match the external ballistics of subsonic .22lr fairly closely. Staying out of the transsonic velocity range seems to eliminate a lot of weirdness.
When a bullet goes sub sonic all sorts of unpredictable things can happen as it can lose stability and start to wobble or even tumble in some circumstances. Staying subsonic eliminates the unstably factor and the bullet will fly true until it hits something.
@@wwalker3738 I wonder if increasing the twist rate for another 20K RPM may help stabilize the projectile as it decelerates through the transonic region. the forces acting on the projectile will be the same, but the higher angular momentum may increase resistance to tumbling.
@@rickmoore6527you can speed up the rpm but…. Once you start over stabilizing, their nose will no longer follow their trajectory and they will start “floating” like a football.thrown really far. And then you lose tracking and all of your bc.
G Day and thank you for all your effort in putting this video together. While I never thought the heal had much of an effect on the 22LR ballistics I offend wondered why they never made a pointy bullet but now your work has shown me why. Thanks Again
I believe your skills/ knowledge may have stumbled upon a hobby that you will find people have great interest in learning more about. Good luck and i hope this ends up being worth your time!
Please, publish a thorough book regarding all things relative to 22LR. Your sales will set your grandchildren for decades. I'll personally buy six copies.
Thank you for the excellent video. Exterior ballistics and how a bullet becomes unstable as it slows down to sub sonic speeds at range has been trouble for centuries. I am happy to hear that the manufacturers are continuing to evolve the venerable 22lr. My Marlin Model 60 has been with me for 35 years and many rifles in other calibers have come and gone in that time. 👍
I found your discussion of comparing modelled results to single data point physical results very interesting. That is quite similar to the way naval architects design ship hulls (my profession for a number of years). We couldn't afford to run models of all the proposed designs down the tow tank, so we used a combination of the results from a standard design series (some of which are very old), and a single design we felt was in the ballpark, as the basis for making small tweaks here are there in the shape of the hull.
I must admit to dabbling a bit in the fluid dynamics of sailing boats. If you look on my channel you will find out what I learned. Sailboats are another example of an old but highly optimized piece of machinery.
@matthewgreenfield1449 Me too! If you look in the comments below, you will find that G1 dates way back to Krupp measuring howitzer shells. No wonder WWI took so long.
The software I'm using does not make modeling spin easy to do. I put several weeks into it without much success, but I might try again. Our bullets go about 64 diameters forward per revolution, so from the bullet's point of view it is pretty slow.
Thinking the platan / nose of the Eley bullet fosters a larger stagnation area. Seems similar to the idea of super cavitation to lessen drag. Don’t really know, but, thought it a possible interesting parallel.
In general, the bore twist rate must also be taken into consideration in 32- 36-, 40-,or 45-grain projectile weights of a mirriad of ammo brands, as the standard 1/16" twist rate is currently challenged by 1/12" and 1/13' twist rates that appear to stabilize the standard forty-grains .22 LR and the thirty-grains .22 Short better than the 1/16" twist rate commonly found in .22s. The 1/9" twist rate for the Aguila SSS 60 grains works, whereas the other twist rates don't. My Walther P22 has a 1/13.4" bore twist rate and does exceptionally well in a 5" bbl. @ 25m using ELEY Match. Therefore, it would be interesting to see how the ELEY Match bullet behaves in other bore twist rates in comparison to the standard 1/16"bore twist rate.
Ahhh so airgunners have some great tables on projectiles in the 750-1050fps range. We call solid bullets like these "slugs" but otherwise we shoot similar profiles, minus the heel. One thing of note is the wind drift, and BC changes at ~950 fps. The wind drift numbers get WORSE at 1000fps and don't get better until 2600fps! Unfortunately most .22LR is much faster than 950fps. If you can maintain subsonic speeds, you WILL get better accuracy, consistency, and less wind drift.
try either capturing (physically [with no impact] or photographically) of the bullets after they leave the barrel to show how the driving band part of the bullet retains it shape or is modified by its contact with the barrel and the rifling as that is the shape that is actually going through the air... the deformation of the driving band may positively affect things as might the longitudinal spirals made by the rifling... I look forward to the results
Interesting how the 24 inch barrel produced slower velocities. I reckon the bullet/rifling dynamic friction was greater than the gains from the added time under pressure for those last 8 inches. I’m thinking that, the powder was fast burning - perhaps designed for short barrel applications - such that the gas pressure had dropped below friction losses. I wonder if the loss of acceleration- while still in the barrel also reduced stability slightly - since bullet spin (in RPM) would also slow a bit. Again, very minor drop in velocity ~10fps - so any stability loss might be too small to measure. However, the take away might be - don’t waste money and effort buying and using a 24 inch barrel.
@@refuztosay9454 I've seen other people report higher velocity with a shorter barrel, so don't take my numbers as an average. Every gun is different, including ones from the same manufacturer. I guess it would be boring if they were predictable!
I can't find it at the moment, but I have enjoyed a UA-camr's video testing for the optimum 22LR barrel length. It was more than 16" but defiantly less than 24". If I find the vid I will post it here.
Few people have any idea of blunt body aerodynamics... I'm always amazed at these rooftop luggage carriers that have a "streamlined" front, and "squared off" tail, when real aerodynamics tell us that it should be mounted "backwards"! I was fortunate to have a friend who was a naval architect, and had written his own graphical fluid dynamics software, in 1980! So, being thirsty to learn..
As the bullet travels thru the air, two sources of drag are present. Nose drag and skin drag. A pointed nose has more surface area for the length covered by a hemisphere. A stepped conical shape can have LESS surface area if the proper angles and lengths are used.
Aside from the spectacular research, and very even keel presentation, I have a great deal of respect for this gentleman for using a Shure SM 58 microphone! Highly underrated tool. Well done. Also, maybe you've already done this, but I'd love to see some 40 Smith & Wesson ballistics content regarding what characteristics a round would need in order to deliver 500 FPE from a 4 inch barrel.
Great video. Fascinating info presented professionally. I hope that as 22 cal precision shooting becomes more popular, we will see some major steps forward in bullet design.
The ideal shape for supersonic projectiles should be the sears haack body, so good modern bullets are some kind of extended ogive with a boat tail, and have drag coefficients that are pretty close. Similarly there should be an ideal shape for transonic and subsonic projectiles, most likely something airfoil and supercritical airfoil shaped. I suspect that that Eley Match is getting pretty close to a stepped supercritical airfoil.
A lot of .22 air rifles are shooting just before that transonic area you referenced. I have several that shoot around 650 to 700 feet per second. It would be very interesting to see a similar video testing out various shapes and weights of pellets for .22 air rifles.
Thanks for the informative video. I have learned a lot about subsonic ballistics shooting pellets and slugs in a .22 caliber PCP air rifle. The difference between spin-stabilized (slugs) and drag-stabilized (Diabolo pellets) is fascinating. Regulated PCP air guns can control the projectile velocity much better (± a few FPS) than firearms ammo so this eliminates a variable. I also shoot .22 LR riles/pistols for reference.
I picked up "Modern Exterior Ballistics: The Launch and Flight Dynamics of Symmetric Projectiles by Robert L. McCoy" many years ago. Can't seem to find it (too many hobbies in front of my books) but I think he focused more on artillery - I don't recall much on small calibers. Then there are 3 dimentional partial diff-eq's; ufdah.....thanks, now I HAVE to find it! But; I was hoping you'd do a wad cutter...... :^)
I have a cnc machine, and a significant background in the hard sciences. I like to fiddle around with making my own bullet molds, especially for shotgun slugs. Is there a free or cheap program I can use for running pressure/ drag models? Possibly something similar to Fusion 360s free version. Ideally it would be able to tell me the center of pressure and center of gravity for a model, but anything would help.
@joearledge1 I use OpenFOAM, which is free, but not at all easy to use. It took me months of work to get a single case to work and report drag, and I had used it twice before.
An interesting video would be tutorial on how you generated the simulation, from freecad modeling and openfoam sim and paraview visualization. I'd like to do this with pellets.
@yootoobvyooer The way OpenFOAM people make money is by teaching classes on all these subjects. It's at least a week's worth of classes to get a Sim like this started. Much more than I would want to take on, and I don't want to interfere with their business.
What’s crazy to me, is with CCi standard in my Savage MK II, I can easily hit soda cans at 150yards, but at 200 yards it all falls apart and everything hits all around the can, and inconsistently. I’m suspecting the bullet is tumbling somewhere in that last 50 yards.
Bullets don’t “tumble” at extended range if they have enough spin for gyro stability at the muzzle. They most likely fly with a sizable non-zero angle of attack and that makes them very sensitive to cross winds.
have you considered modeling bullet heads that have been fired. The soft lead heel of a .22lr changes shape... they basically turn into a G1 profile when they leave the barrel.
@@jamesconger8509 You might be able to look up slow motion footage of .22 bullets and use that to model the shape after being fired. (I don't know where that would be found though)
@@jamesconger8509 You may be able to fire the bullets into a low-density medium such as a large pile of fleece blankets to recover them without damage. I am pretty sure I have seen that be a successful method before. Aside from using a high-speed camera that may be the best option.
@@jamesconger8509 I will attest to the idea the 22 heeled bullets change shape. I've recovered dozens of projectiles, anything from the 20gr colibri, eley match, to the 60gr snipers. I've normally been able to capture these after they pass through game and they bury themselves into snow or soft dirt. I've also recovered bullets buy shooting them into dense snow and they come out perfect. Fired 22lr bullets will no longer have a heel. I think it's a common misconception that I've heard other channels over look. I would be interested on your take on this. Thanks for video.
@@joeneu I'd be interested in any pictures you might have of recovered bullets, particularly the Eley. They have a convex back end which may deform from the pressure of the charge.
Enjoyed the video. A lot of good information in there. My comment is about the shape of the bullet you modeled. I have seen high speed videos of 22 LR bullets exiting the muzzle. In both of them the heel of the bullet had obturated to fit the rifle bore diameter. One of those videos is by "Balistic High-Speed", I can't find the other one right now. I don't know what ammo they were using or what the velocity was. May not be the same for subsonic ammo as it is for high velocity ammo.
So, if I'm understanding this correctly, the ideal velocity would be below or above the trans-sonic range, correct? So wouldn't it be better to have the bullet never hit that range if you're shooting at distances that are short enough to avoid excessive bullet drop? The same would be true for longer distances, where the bullet stays at supersonic velocity and never falls into the trans-sonic range, right? Wouldn't adhering to this basic premise avoid the problems that occur when the bullet enters this trans-sonic range? Why would you make a cartridge that stays in that velocity range, like the CCI standard at 1070 fps? That velocity is right in the middle of the 'trouble zone'. Edit: great video!
The barrel length data shows that the pressure of the small powder charge drops below barrel friction beyond the 16" barrel for these loads. I always thot so... But I only have my 5.5" target pistol and my Ruger 10-22 18", so had no way to test that. Very interesting show. Eons ago, Herters made some coke bottle shaped 22 bullets - it was known that wasp waisted aircraft had lower drag... It might be interesting to model them vs. say Hornady spires vs. Sierra spitzers. They shot well in my 222 Rem. IF they maintained shape in the barrel, they would have less barrel friction, too. I thimque I may still have a few around someplace. I may load some to compare BC's with my Lab Radar...
James, if you recover a fired .22 LR bullet from a deep water tank, the base is bulged out to meet the barrel groove diameter, by means of sudden application of high pressure gas ahead of the chamber. So, the bullet base "in flight" does not look like it does, before firing. Certainly, full depth land impressions can be observed almost all the way to the rear of a fired .22 LR bullet. If Eley are attempting to mimic a boat tail bullet shape after firing, the rifling spin requirements for stable flight will exceed the typical 1:16 for a .22 LR barrel.
@@rickoshea8138 Thanks. It looks like the heal expands enough to merge with the outer diameter of the bullet. Good for stability, but bad for drag. I would choose stability any day.
They sell your "pointy" modified low drag bullet for 22LR handloading. It's expensive and handloading 22LR is a pain, but it's marketed towards ELR shooters.
Good stuff. I know that you are focusing on long-range target ammo, but I would love to see some basic comparisons with more standard 22 LR bullet profiles like Stingers or Punch. Ubuntu user. I'll checkout Freecad. Thanks
Been a while since I saw you last, apparently you are having fun without bow & arrow these days. Great video, I personally like 22LR CCI copper tips hollow points for quite decent accuracy up to 200 yards.
I'd be interested to see what would happen to drag with a blunt nose and a long pointy tail. It's an unrealistic design but it would be cool to see the effects at all speeds
You should verify the shape/profile of a fired 22lr bullet. The obturation of the heel and swaging by the leade changes the shape from the heeled projectile you show, to a round nose cylinder, with no diameter change at what used to be the crimp line. Bullets recovered from a snowbank, water tank, poly-fil trap all show the crimp line and smaller diameter heel have been reshaped to a uniform diameter from the leading edge of the drive bands to the cupped heel.
It is clear that the objective of your analysis is to accurately determine drag coefficients for your rifle's bullet/barrel, so as to accurately estimate correct DOPE for bullet drop and perhaps time-of-flight at various target distances. Your results confirm the proper (idealized) CD model that should be used for your external ballistic calculations and apply it to verified measured velocities based on muzzle chronograph readings and bullet-drop range testing using your individual firearm. The CFD results are interesting and informative. I'd be curious to review a comparison of CFD analysis from measured bullet configurations of commercially available offerings from various suppliers (CCI, Federal, SK, Ely, Aguila, Wolf, Norma etc.). Additionally, it occurs to me that rotational drag must necessarily reduce RPM and therefore impact external ballistics performance. I've long suspected that the standard 1:16 22 LR twist rate may be insufficient to stabilize bullets through the transonic velocity 'wall' and especially as drag at longer distance significantly impacts linear velocity. SV 22 rimfire ammo leaves the rifle muzzle at approx 1080 FPS or 48.6K RPM. Rotational drag heats the air and robs bullet rotational energy, thus providing increasingly less stability as time-of flight increases. I expect this may be a second-order effect to overall instability and increasing target group sizes at longer distance, but to my knowledge, that rotational contribution has not been modeled or analyzed. Discuss...
@rickmoore6527 I don't think I will ever be able to complete with simply shooting the bullets and measuring the muzzle velocity and the drop at distance. That is such a direct way to measure drag. What I got from the models is just a general understanding of how these bullets perform and how to best use my ballistic calculator.
You might find the black powder cartridge shooter's bullets interesting. 45-70 being the starting point. 500 grain, 1350 fps. Transsonic is the major part of the ballistic zone. Hundreds of bullet shapes: roundnose, creedmore, postel, money, flatnose, to name a few. Range out beyond 1000 yard shooting matches. Look at "Black Powder Cartridge News" magazine, also "Down Range Data" by William T. Falin Jr.
Stabilizing "pointy" bullets has been achieved with 8.5 Blackout. They do this with increasing rifling to a 1 and 3 twist rate. I wonder if doing something similar with .22 could be modeled?
Great video Sir! Thank you for the effort. I would be very much interested to see what your simulation says about boattails. It should have a great affect. If you look at Soviet VSS ammo SP5/6 they have large boattails. R.L McCoy's book that i have doesn't go into subsonic regime either but recognizes the effect of boattails and claims that shepe of the nose has little effect. I'm building a powerfull airgun for the competition you mentioned, and i believe this is where airguns will outperform .22LR subs
I have not done much past the sims I posted. Keep in mind that making a bullet longer to lower the drag will reduce the stability of the bullet, so you probably need to think about tighter rifling twist if you are going in that direction. And yes, air guns have a lot more flexibility, plus amazing repeatability.
@jamesconger8509 Agreed. The bullet actually becomes too long, in a sence that sectional density exceeds modern air rifle capabilities forcing you to crank up the pressure. Gyroscopic stability is fairly simple to calculate, it's the dynamic stability that i don't understand how to calculate. Having a cavity in the back vs front ( reducing SD to acceptible levels) has an effect as well, just not clear on how to calculate it. Anyway...looking forward to your future research! Thank you for sgaring!
With the designs that have a steep increase in drag as it goes supersonic, it is possible to take advantage of this to reduce vertical dispersion at long range. It is sometimes called "Mach trimming". The bullet is loaded to just above the critical mach number. This way, the bullet reliably slows to its max subsonic speed soon after leaving the muzzle. Believe it or not, this often produces more uniform bullet speeds downrange than trying to launch each round at precisely the same (subsonic) muzzle velocity.
@@jfess1911 I have heard of this, but given how the speed of sound varies with conditions, it would seem like something only an air rifle could hope to do consistently, and it would be a pain to keep adjusting the muzzle velocity, which would also change the ballistics. Life is too short for this.
@@jamesconger8509 Bryan Litz has some interesting articles on Mach Trimming. He did quite a lot of radar testing on it. There is also a video here on YT with him being interviewed about it. You are right that it is.a pain to match the bullet to the speed of sound for changing conditions. One interesting point he brings up (along with high-speed photos of a shot 22 bullet) is that the shape of a fired .22 bullet is not the same as an unfired one. A photo of the bullet leaving the muzzle shows no heel section. It has obturated inside the bore to match the shank diameter.
@@jfess1911 Thanks. That implies that the sims I did for the no-heal case might actually reflect the bullet as fired. The shape of the drag curve was the same, so the same approach applies.
@@jamesconger8509 That video interview is on the Ultimate Reloader channel, if you want a look. The photo is shown there. There are also a couple short ones on Litz's Applied Ballistics channel. Litz stated that none of the existing ballistic curves do a great job of matching the 22 LR trajectories he saw with the radar. Now that I have looked farther into it, I agree that Mach trimming seems impractical. It looks like you might need a barrel with numerous ports drilled along its length that could be covered and uncovered to produce the perfect velocity from a batch of ammo . I have a silly imagination and pictured a sliding trombone-like device attached near the chamber tap off the desired amount of gas. Yes, I know it is ridiculous, but the image in my head is pretty funny!
1: Isn't there a partial vacuum behind the bullet?... 2: Is it possible for the bullet to create a vapor or condensation trail behind in a humid environment? 3: Could a motion pucture camera operating at 42 frames per second capture that trail before it evaporates?
I don't know. There is a little low pressure region right behind the bullet, but the wake is also heated up by the bullet's passing, which would tend to make any mist evaporate. I've shot in 100% humidity and never noticed a vapor trail, but that doesn't mean it can't happen.
@jamesconger8509 : Thanks. I mention it as there's a famous photo of a streak photographed passing Trump's head. And a certain frame of the Zapruder film of JFK's assassination wherein a streak appears passing behind the driver's head as the President's head is hit.
4:09 The velocity of air rises to above 0.73M around the ogive, lowering the temperature. As it reaches the heel, velocity drops (skin drag is a contributor), temperature and pressure rise. Subsonic diffuser flow conditions. I don’t think you included internally generated heat into your simulation, so the bullet temperature is probably not the cause.
I adjust my speed in the kestrel to match the real bullet flight out to 200 yards regardless of what my chronograph says. I just use the chrono to identify flyers/ES outliers while im getting dope. After 200 I adjust the AB 'drop scale factor' in the kestrel. G1 also works well but i really like how easy the DSF feature makes it to get a good dope card. Loved the video thank you for the lesson.
I think the reason this works for you is that you are working around the poor fit of the G1 model by adjusting the muzzle velocity. Try using the G7 model with a BC of around 0.069 and the measured muzzle vel. I think you will find it fits the data better. BTW: I used to do exactly what you are doing.
I'm surprised this only has 230 views, especially considering how informative and well spoken this is.
It's just been out for 1 day, so I'm pretty happy with the response, but thanks for the vote of confidence.
It's because the horrible background music.
The problem, as usual, it’s the lack of humans to make the difficult action to click on thumb up, that is a shame!
Sadly, that's exactly why it doesn't get very much love from the algorithm. We have to hunt around for channels like this gem.
4 days posted and nearly 8000 views.
I've been shooting my entire adult life, and I'm older, and I now know more about bullet aerodynamics and ballistics - in general - than I ever did. Thank you, Sir.
Thanks for the kind words.
This is a fantastic video. Extremely well done. Thank you !
It's mind boggling (to me at least) that the heel on the bullet does not ruin the ballistics of the projectile.
Same here. Eley tapers the back end of the heal, so it approximates a more modern bullet. That might be part of the explanation.
Most times when something gets smaller on the tail it improves aerodynamics - like those big fold-out panels on semi trailers.
@@19Borneo67 Also the the extended 'boat tails', on the race cars at LaMans in the '70s. I was closely watching the NASA research on drag reduction on semi trucks, also in the mid '70s, I believe. The further they extended the faring out past the flat rear of the trailer the more aerodynamically efficient the vehicle became.
More or this. As an engineer student. I love it.
In the research you will notice that boattails dont do much at subsonic velocities (yet everyone mistakenly wants a boattail for its supposed improved lower drag). However, if you check the data, you'll see that a heel or gas check rebated base (without the gas check) has a very good a drag reduction at subsonic compared to a flat base projectile. There's some other advantages to a healed bullet and that is when a boattail is exiting the muzzle the gas jetting around the boatail tends to knock the tail off to rhe side slightly and so the bullet base 'spirals' or hunts for the first 50 to 100 yards before settling down. The crown of the muzzle is critical to launching a projectile smoothly. A flat base bullet exiting a cocked muzzle will get a jet on one side first and be knocked off quite a bit too BUT the healed bullet is affected least by this.
I shoot bigger bore cast bullets, very long range and subsonic only, not 22LR and I've gone pretty much all healed designs (ordered as gas check molds but no gas check is ever used). I'm not ordering stock molds, im having my own custom designs done (ie: at Accurate Molds and even 4 of my designs at NOE Molds).
Note that boattails are especially poor dropping down into subsonic at extreme ranges which is a problem the military has delt with for years with it ELR sniper rounds, the further down range around trans-sonic, the MOA jumps up a lot.
And further, ive found that a flat meplat of 62% to 70% projectile diameter has a better Drag Coefficient than a rounded or pointed nose as you indicated in your video. The nice thing is that a hollow point loads up with air and becones the same drag as a solid flat meplat, so i use a HP aa necessary to adjust the CG of the bullet and move it aft (and some of them are good hunting rounds too, search for NOE mold # 358-152-HP-CF4 but shot without the gas check. Shot at 950 FPS its not lubed but the grooves give reduced bore friction, but the contact length gives it good internal ballistic stability (not cocking in the bore like a lot of shorter bullets) and a fair length for external ballistics (of course the ideal is 6:1 but in this caliber for subsonic flight only it gets shortened). The mentioned projectile, shot subsonic, gets MOA at 500 yards so I'm pretty proud of it.
And I thought I took my hobby seriously! You have me beat by a long shot (pun intended)!
@@jamesconger8509 I'd note that I might cast 200 bullets but by the time I QC them and eliminate any with weight variations (they all have to be visually perfect but MUST weigh within 0.01 grains) I get around 30 match grade slugs. And I consider myself an expert caster and have probably cast around 15,000 to 16,000 bullets (and shot them too!). I HAVE to shoot into bullet traps because I need to recycle the lead to save money. I have a range on my own property with 25, 50, 85 and 100 yard target stands (and a trap behind each)
Why 85 yards? Because at 950 FPS, an 85 yard zero gives +-3" high at 50 yards and +-3" low at 100 yards. All my subsonic rifles are zeroed at 85 so I can swap from rifle to rifle and all hit the same point of aim.
And I hunt a lot of hogs all year round, it simplifies drop calculations when aiming if you don't know the exact yards.
You rock. That explains why my Accurate Mold for .447 concicals with a gas check shoots so damned well in my cap and ball guns. It's point of aim up to 25 yards with 30 grains of Swiss. My friends were impressed whch ish ard to do .
Excellent balance between being clear and being absolutely technically accurate. I didn’t hear anything that you said that was “wrong” and you didn’t get lost in the weeds. As an ex-CFD guy, I would tend to get overly detailed and caveated for my audience (management) in an effort to be totally transparent. They just got bored or confused, or both. I did that because I learned the hard way that Box’s quote, “All models are wrong, but some are useful.” is really true. CFD can be a very useful tool, but it isn’t Truth. Some people take the simulation outputs as Gospel and don’t run them through the BS-o-meter, which can bite you. I am interested in OpenFOAM now to see what it is as I am now retired and don’t have access to the industrial codes any more. Thanks for an excellent presentation of your work!
@andrewhahn1476 Thanks, and thanks for reminding me of that great quote. One thing I have found throughout my career is that building models is a key to understanding a subject. Once you get that understanding, it is best to throw the model away.
The G/1 model was first developed for artillery back in the first world war where they were predicting the trajectory of hundred pound artillery shells. They were all flat base and short nosed. It’s kind of a holdover. And because it has the highest number, manufactures will not give it up. 17:35
Thanks for the background, especially about why it lingers. Sigh...
Yeah, unfortunately, it's often the only apples to apples comparison. Before the G7 came out, it was THE bullet BC . Of the people who cared about BC and out of the companies that published it back then, the oversimplification was more higher BC = more better bullet. This was before the internet, so mass education on complex subjects wasn't really a thing. Basically a marketing holdover, although some classic bullet designs still fit the model. I think it was Krup munitions company that came out with G1, might be wrong though. Now "custom drag curves" are putting G7 out of business, though manufacturers will probably never stop reporting G1 and/or G7.
I was about to post something similar, except that I believe G1 model dates back to the late Victorian era around the advent of smokeless powder for artillery. It is NOT a model suitable for small arms ballistics except in the subsonic regime, as I understand it, but my knowledge is admittedly limited.
@@nunyabidniz2868 Yeah I vaguely recall that timeline too. Without looking, I don't know for sure when. I'm fairly certain it was Krup munitions that came up with it, but that might be incorrect too. Definitely appeared somewhere between 1850 and 1918 after the popularization of conical projectiles. It applies to small arms and arty, it's just not as accurate as we'd like, but better than nothing. This was a time when sub moa groups weren't really a thing, even in competition circles. I'm sure it happened, but wasn't the norm. 3 to 6 moa was fairly standard for precision. I'm sure arty has changed in a similar way. So in those cases, a "close enough" model is "good enough".
The G1 does match most 22lr bullets closer than G7 though. It's the only time I'd consider using G1. Thankfully there are lots of bullet specific custom profiles out there now
Thanks. I appreciate the informative data and sharing what you learned. The influence of its CG to be less resistant to tumbling down range was insightful. One of those things that makes sense but I never thought about. I’ve always wondered how much rifling grooves impacts the flow around it but for larger projectiles amongst other things. Anyways thanks.
Very well done... and the best thing, besides seeing that the bullet shapes are already optimized, was seeing that the increase in the barrel reduced the speed of the bullet, making the 16" long one better ... ! 😮❤
I really enjoyed this, thank you sir.
Physics is Fun
Thanks for the great presentation!
I have noticed that most subsonic rifle bullets match the external ballistics of subsonic .22lr fairly closely. Staying out of the transsonic velocity range seems to eliminate a lot of weirdness.
When a bullet goes sub sonic all sorts of unpredictable things can happen as it can lose stability and start to wobble or even tumble in some circumstances.
Staying subsonic eliminates the unstably factor and the bullet will fly true until it hits something.
@@wwalker3738 I wonder if increasing the twist rate for another 20K RPM may help stabilize the projectile as it decelerates through the transonic region. the forces acting on the projectile will be the same, but the higher angular momentum may increase resistance to tumbling.
@@rickmoore6527you can speed up the rpm but…. Once you start over stabilizing, their nose will no longer follow their trajectory and they will start “floating” like a football.thrown really far. And then you lose tracking and all of your bc.
Incredibly interesting, informative and relaxing video!
Awesome information perfectly explained 👏
G Day and thank you for all your effort in putting this video together. While I never thought the heal had much of an effect on the 22LR ballistics I offend wondered why they never made a pointy bullet but now your work has shown me why. Thanks Again
Yeah, it means the new .21 sharp ain't ever going to replace .22lr...
Part 2? Anything missing that you want to add ?? Really enjoyed this video!
Thanks!
I believe your skills/ knowledge may have stumbled upon a hobby that you will find people have great interest in learning more about.
Good luck and i hope this ends up being worth your time!
I'm quite happy I came upon this video. Very informative, I'll give your other videos a try, even if they are not exactly ballistic themed :)
Please, publish a thorough book regarding all things relative to 22LR. Your sales will set your grandchildren for decades. I'll personally buy six copies.
Great video, thanks for taking the time to share your models and findings!
@@myersarmsllc Thanks for the kind words.
Thank you for the excellent video. Exterior ballistics and how a bullet becomes unstable as it slows down to sub sonic speeds at range has been trouble for centuries. I am happy to hear that the manufacturers are continuing to evolve the venerable 22lr. My Marlin Model 60 has been with me for 35 years and many rifles in other calibers have come and gone in that time. 👍
My Model 60 will have been with me 40 years this Christmas.
@colby7625 That is the best Christmas gift I have ever heard of. Happy Holidays
Wow! This is excellent stuff! I'm subscribed.
Great video, with good usable conclusions!
Excellent presentation
I found your discussion of comparing modelled results to single data point physical results very interesting. That is quite similar to the way naval architects design ship hulls (my profession for a number of years). We couldn't afford to run models of all the proposed designs down the tow tank, so we used a combination of the results from a standard design series (some of which are very old), and a single design we felt was in the ballpark, as the basis for making small tweaks here are there in the shape of the hull.
I must admit to dabbling a bit in the fluid dynamics of sailing boats. If you look on my channel you will find out what I learned. Sailboats are another example of an old but highly optimized piece of machinery.
Couldn't have had a better Christmas season than being able to consider this information. Thank you, Santa!
Great Information and explanation.
Very informative, thank you!
Thanks for showing the comparison for a G1 curve. I have tried using G1 curves on the past with poor results.
@matthewgreenfield1449 Me too! If you look in the comments below, you will find that G1 dates way back to Krupp measuring howitzer shells. No wonder WWI took so long.
Spin rotation is also dragging air around the rotational axis although minimal it factors in.
The software I'm using does not make modeling spin easy to do. I put several weeks into it without much success, but I might try again. Our bullets go about 64 diameters forward per revolution, so from the bullet's point of view it is pretty slow.
Thinking the platan / nose of the Eley bullet fosters a larger stagnation area. Seems similar to the idea of super cavitation to lessen drag. Don’t really know, but, thought it a possible interesting parallel.
thanks for sharing, it's a great video about rimfire shooting. Hope for more great videos like this one in the future.
In general, the bore twist rate must also be taken into consideration in 32- 36-, 40-,or 45-grain projectile weights of a mirriad of ammo brands, as the standard 1/16" twist rate is currently challenged by 1/12" and 1/13' twist rates that appear to stabilize the standard forty-grains .22 LR and the thirty-grains .22 Short better than the 1/16" twist rate commonly found in .22s. The 1/9" twist rate for the Aguila SSS 60 grains works, whereas the other twist rates don't. My Walther P22 has a 1/13.4" bore twist rate and does exceptionally well in a 5" bbl. @ 25m using ELEY Match. Therefore, it would be interesting to see how the ELEY Match bullet behaves in other bore twist rates in comparison to the standard 1/16"bore twist rate.
0 seconds of the video watched, liked and subscribed, i already know this is going to be good based on the title and the thumbnail
Ahhh so airgunners have some great tables on projectiles in the 750-1050fps range. We call solid bullets like these "slugs" but otherwise we shoot similar profiles, minus the heel. One thing of note is the wind drift, and BC changes at ~950 fps. The wind drift numbers get WORSE at 1000fps and don't get better until 2600fps! Unfortunately most .22LR is much faster than 950fps. If you can maintain subsonic speeds, you WILL get better accuracy, consistency, and less wind drift.
@@life_of_riley88 absolutely, it's a much different shooting experience than firearms but very satisfying.
I was wondering if an airgunner would post. This is a great video, but any good rat sniper knows all this. Especially trans-sonic velocity issues.
try either capturing (physically [with no impact] or photographically) of the bullets after they leave the barrel to show how the driving band part of the bullet retains it shape or is modified by its contact with the barrel and the rifling as that is the shape that is actually going through the air... the deformation of the driving band may positively affect things as might the longitudinal spirals made by the rifling... I look forward to the results
Thanks Very technical but you explain well enough to follow.
Thanks for the kind words.
Great video. Clears up a lot of questions.
As someone who builds pcps as a hobby this video is absolute gold. Thanks for making this.
I am using Lapua because of the proximity of their test facility. Their bullet is a bit more pointed.
Awesome video!!💯
Great vid - looking forward to more like this.
Interesting how the 24 inch barrel produced slower velocities. I reckon the bullet/rifling dynamic friction was greater than the gains from the added time under pressure for those last 8 inches. I’m thinking that, the powder was fast burning - perhaps designed for short barrel applications - such that the gas pressure had dropped below friction losses. I wonder if the loss of acceleration- while still in the barrel also reduced stability slightly - since bullet spin (in RPM) would also slow a bit. Again, very minor drop in velocity ~10fps - so any stability loss might be too small to measure. However, the take away might be - don’t waste money and effort buying and using a 24 inch barrel.
@@refuztosay9454 I've seen other people report higher velocity with a shorter barrel, so don't take my numbers as an average. Every gun is different, including ones from the same manufacturer. I guess it would be boring if they were predictable!
I can't find it at the moment, but I have enjoyed a UA-camr's video testing for the optimum 22LR barrel length. It was more than 16" but defiantly less than 24". If I find the vid I will post it here.
Few people have any idea of blunt body aerodynamics... I'm always amazed at these rooftop luggage carriers that have a "streamlined" front, and "squared off" tail, when real aerodynamics tell us that it should be mounted "backwards"!
I was fortunate to have a friend who was a naval architect, and had written his own graphical fluid dynamics software, in 1980! So, being thirsty to learn..
Look up notch airfoils or Kline Fogleman airfoils.
Quite common in high performance model aircraft.
They don’t scale up very well.
As the bullet travels thru the air, two sources of drag are present. Nose drag and skin drag. A pointed nose has more surface area for the length covered by a hemisphere. A stepped conical shape can have LESS surface area if the proper angles and lengths are used.
Great vid mate!
@@drewbailey5653 Thanks!
Maybe this should be a gun channel!? Well done!
Aside from the spectacular research, and very even keel presentation, I have a great deal of respect for this gentleman for using a Shure SM 58 microphone! Highly underrated tool. Well done.
Also, maybe you've already done this, but I'd love to see some 40 Smith & Wesson ballistics content regarding what characteristics a round would need in order to deliver 500 FPE from a 4 inch barrel.
Very interesting video Mr. Conger please make more on other calibers!
Great video. Fascinating info presented professionally. I hope that as 22 cal precision shooting becomes more popular, we will see some major steps forward in bullet design.
Thanks. I'm increasingly thinking that these little guys have been pretty well optimized already. I should give them more credit!
This is a top notch, super excellent vid.
Thanks for your work.
Jk; you blinded me with science!
The ideal shape for supersonic projectiles should be the sears haack body, so good modern bullets are some kind of extended ogive with a boat tail, and have drag coefficients that are pretty close.
Similarly there should be an ideal shape for transonic and subsonic projectiles, most likely something airfoil and supercritical airfoil shaped.
I suspect that that Eley Match is getting pretty close to a stepped supercritical airfoil.
Thank you, very informative and interesting.
Nice presentation. I would also like to see the vorticity maps and correlate them to the drag. Thank you!
A lot of .22 air rifles are shooting just before that transonic area you referenced. I have several that shoot around 650 to 700 feet per second. It would be very interesting to see a similar video testing out various shapes and weights of pellets for .22 air rifles.
@@brianwilke592 You are the fourth person to suggest that!
@17:40 The Eley Match FPS rating on my box is 1085, not 1065, so almost exactly the result through the 16" Ruger.
Thanks for the informative video.
I have learned a lot about subsonic ballistics shooting pellets and slugs in a .22 caliber PCP air rifle.
The difference between spin-stabilized (slugs) and drag-stabilized (Diabolo pellets) is fascinating.
Regulated PCP air guns can control the projectile velocity much better (± a few FPS) than firearms ammo so this eliminates a variable.
I also shoot .22 LR riles/pistols for reference.
A friend was showing me his air rifle slugs a couple of nights ago, and they look like a lot of thought has gone into the design for high BC.
The first lesson of aerodynamics, air is easily deceived .
I picked up "Modern Exterior Ballistics: The Launch and Flight Dynamics of Symmetric Projectiles by Robert L. McCoy" many years ago. Can't seem to find it (too many hobbies in front of my books) but I think he focused more on artillery - I don't recall much on small calibers. Then there are 3 dimentional partial diff-eq's; ufdah.....thanks, now I HAVE to find it! But; I was hoping you'd do a wad cutter...... :^)
very interesting and great and understandable explained 🙂
Great video
I have a cnc machine, and a significant background in the hard sciences. I like to fiddle around with making my own bullet molds, especially for shotgun slugs. Is there a free or cheap program I can use for running pressure/ drag models? Possibly something similar to Fusion 360s free version. Ideally it would be able to tell me the center of pressure and center of gravity for a model, but anything would help.
@joearledge1 I use OpenFOAM, which is free, but not at all easy to use. It took me months of work to get a single case to work and report drag, and I had used it twice before.
An interesting video would be tutorial on how you generated the simulation, from freecad modeling and openfoam sim and paraview visualization. I'd like to do this with pellets.
@yootoobvyooer The way OpenFOAM people make money is by teaching classes on all these subjects. It's at least a week's worth of classes to get a Sim like this started. Much more than I would want to take on, and I don't want to interfere with their business.
What’s crazy to me, is with CCi standard in my Savage MK II, I can easily hit soda cans at 150yards, but at 200 yards it all falls apart and everything hits all around the can, and inconsistently. I’m suspecting the bullet is tumbling somewhere in that last 50 yards.
Bullets don’t “tumble” at extended range if they have enough spin for gyro stability at the muzzle. They most likely fly with a sizable non-zero angle of attack and that makes them very sensitive to cross winds.
@@jeffsiewert1258 Maybe you are wrong.
@deandeann1541 I think 45+ years as a ballistics engineer says otherwise.
@@jeffsiewert1258 $5 years means nothing if you cannot back up your opinion with data. I will provide my data if you will provide yours.
That P47 doesn't have a blunt nose, it has a great big gaping hole for the air to pass through and cool the engine.
@@jimlongley9531 True! But tell me you don't see a Thunderbolt when you look at the CAD image of an Eley 22!
@@jamesconger8509 There is a vague resemblance, but not close enough to make the comparison that you do.
have you considered modeling bullet heads that have been fired. The soft lead heel of a .22lr changes shape... they basically turn into a G1 profile when they leave the barrel.
@@hunt3r827 How would I collect a sample bullet without further deforming it?
@@jamesconger8509 You might be able to look up slow motion footage of .22 bullets and use that to model the shape after being fired. (I don't know where that would be found though)
@@jamesconger8509 You may be able to fire the bullets into a low-density medium such as a large pile of fleece blankets to recover them without damage. I am pretty sure I have seen that be a successful method before. Aside from using a high-speed camera that may be the best option.
@@jamesconger8509 I will attest to the idea the 22 heeled bullets change shape. I've recovered dozens of projectiles, anything from the 20gr colibri, eley match, to the 60gr snipers. I've normally been able to capture these after they pass through game and they bury themselves into snow or soft dirt. I've also recovered bullets buy shooting them into dense snow and they come out perfect.
Fired 22lr bullets will no longer have a heel. I think it's a common misconception that I've heard other channels over look. I would be interested on your take on this.
Thanks for video.
@@joeneu I'd be interested in any pictures you might have of recovered bullets, particularly the Eley. They have a convex back end which may deform from the pressure of the charge.
Wow!!!! very interesting!!!!
Lovely stuff. Thanks for sharing. 🖖
Enjoyed the video. A lot of good information in there.
My comment is about the shape of the bullet you modeled. I have seen high speed videos of 22 LR bullets exiting the muzzle. In both of them the heel of the bullet had obturated to fit the rifle bore diameter. One of those videos is by "Balistic High-Speed", I can't find the other one right now. I don't know what ammo they were using or what the velocity was. May not be the same for subsonic ammo as it is for high velocity ammo.
So, if I'm understanding this correctly, the ideal velocity would be below or above the trans-sonic range, correct? So wouldn't it be better to have the bullet never hit that range if you're shooting at distances that are short enough to avoid excessive bullet drop? The same would be true for longer distances, where the bullet stays at supersonic velocity and never falls into the trans-sonic range, right? Wouldn't adhering to this basic premise avoid the problems that occur when the bullet enters this trans-sonic range? Why would you make a cartridge that stays in that velocity range, like the CCI standard at 1070 fps? That velocity is right in the middle of the 'trouble zone'. Edit: great video!
@@godzillaburger9690 The air gun folks favor low velocity when they are shooting short distances, I think for the reasons you state.
The barrel length data shows that the pressure of the small powder charge drops below barrel friction beyond the 16" barrel for these loads. I always thot so... But I only have my 5.5" target pistol and my Ruger 10-22 18", so had no way to test that. Very interesting show.
Eons ago, Herters made some coke bottle shaped 22 bullets - it was known that wasp waisted aircraft had lower drag... It might be interesting to model them vs. say Hornady spires vs. Sierra spitzers. They shot well in my 222 Rem. IF they maintained shape in the barrel, they would have less barrel friction, too. I thimque I may still have a few around someplace. I may load some to compare BC's with my Lab Radar...
Great video,thx
James, if you recover a fired .22 LR bullet from a deep water tank, the base is bulged out to meet the barrel groove diameter, by means of sudden application of high pressure gas ahead of the chamber. So, the bullet base "in flight" does not look like it does, before firing.
Certainly, full depth land impressions can be observed almost all the way to the rear of a fired .22 LR bullet.
If Eley are attempting to mimic a boat tail bullet shape after firing, the rifling spin requirements for stable flight will exceed the typical 1:16 for a .22 LR barrel.
@rickoshea8138 Any chance of a close-up photograph?
@@jamesconger8509 YTSearch for:
22LR Accuracy UNKNOWN SECRETS Found?
You should find a video on STKO
@@jamesconger8509 Search:
STKO 22LR Accuracy UNKNOWN SECRETS Found?
Look for this string:
STKO 22LR Accuracy UNKNOWN SECRETS Found
@@rickoshea8138 Thanks. It looks like the heal expands enough to merge with the outer diameter of the bullet. Good for stability, but bad for drag. I would choose stability any day.
Thank you for this very interesting video. Best regards :)
They sell your "pointy" modified low drag bullet for 22LR handloading. It's expensive and handloading 22LR is a pain, but it's marketed towards ELR shooters.
Great video, first one I have heard of about the 22 lr. Thanks.
@@rogerdavis2056 Thanks for the note.
Good stuff. I know that you are focusing on long-range target ammo, but I would love to see some basic comparisons with more standard 22 LR bullet profiles like Stingers or Punch. Ubuntu user. I'll checkout Freecad. Thanks
Earned a sub 😊
Been a while since I saw you last, apparently you are having fun without bow & arrow these days.
Great video, I personally like 22LR CCI copper tips hollow points for quite decent accuracy up to 200 yards.
@bernhardgoesmann6490 Thanks Bernard. You ever try NRL22? Closest thing to field archery, and quite a challenge.
I'd be interested to see what would happen to drag with a blunt nose and a long pointy tail. It's an unrealistic design but it would be cool to see the effects at all speeds
What about a raindrop ?
Brian doesn’t need to fix the book you just did.
You should verify the shape/profile of a fired 22lr bullet.
The obturation of the heel and swaging by the leade
changes the shape from the heeled projectile you show,
to a round nose cylinder, with no diameter change
at what used to be the crimp line.
Bullets recovered from a snowbank, water tank, poly-fil trap
all show the crimp line and smaller diameter heel
have been reshaped to a uniform diameter from the leading edge of the drive bands to the cupped heel.
Several people have made that comment. The "no heel" model in the video might be the base case.
Thank you for the excellent, informative video.
Love this! 22lr🤌
It is clear that the objective of your analysis is to accurately determine drag coefficients for your rifle's bullet/barrel, so as to accurately estimate correct DOPE for bullet drop and perhaps time-of-flight at various target distances. Your results confirm the proper (idealized) CD model that should be used for your external ballistic calculations and apply it to verified measured velocities based on muzzle chronograph readings and bullet-drop range testing using your individual firearm. The CFD results are interesting and informative.
I'd be curious to review a comparison of CFD analysis from measured bullet configurations of commercially available offerings from various suppliers (CCI, Federal, SK, Ely, Aguila, Wolf, Norma etc.).
Additionally, it occurs to me that rotational drag must necessarily reduce RPM and therefore impact external ballistics performance. I've long suspected that the standard 1:16 22 LR twist rate may be insufficient to stabilize bullets through the transonic velocity 'wall' and especially as drag at longer distance significantly impacts linear velocity. SV 22 rimfire ammo leaves the rifle muzzle at approx 1080 FPS or 48.6K RPM. Rotational drag heats the air and robs bullet rotational energy, thus providing increasingly less stability as time-of flight increases. I expect this may be a second-order effect to overall instability and increasing target group sizes at longer distance, but to my knowledge, that rotational contribution has not been modeled or analyzed.
Discuss...
@rickmoore6527 I don't think I will ever be able to complete with simply shooting the bullets and measuring the muzzle velocity and the drop at distance. That is such a direct way to measure drag. What I got from the models is just a general understanding of how these bullets perform and how to best use my ballistic calculator.
You might find the black powder cartridge shooter's bullets interesting. 45-70 being the starting point. 500 grain, 1350 fps. Transsonic is the major part of the ballistic zone. Hundreds of bullet shapes: roundnose, creedmore, postel, money, flatnose, to name a few. Range out beyond 1000 yard shooting matches. Look at "Black Powder Cartridge News" magazine, also "Down Range Data" by William T. Falin Jr.
Thanks. Will do.
Stabilizing "pointy" bullets has been achieved with 8.5 Blackout. They do this with increasing rifling to a 1 and 3 twist rate. I wonder if doing something similar with .22 could be modeled?
@jmonty If I get bored, I might examine stability. I'm curious how the shape affects the forces that push a bullet off course.
@@jamesconger8509 look into spin drift if you haven't already
Great video Sir! Thank you for the effort. I would be very much interested to see what your simulation says about boattails. It should have a great affect. If you look at Soviet VSS ammo SP5/6 they have large boattails. R.L McCoy's book that i have doesn't go into subsonic regime either but recognizes the effect of boattails and claims that shepe of the nose has little effect. I'm building a powerfull airgun for the competition you mentioned, and i believe this is where airguns will outperform .22LR subs
I have not done much past the sims I posted. Keep in mind that making a bullet longer to lower the drag will reduce the stability of the bullet, so you probably need to think about tighter rifling twist if you are going in that direction. And yes, air guns have a lot more flexibility, plus amazing repeatability.
@jamesconger8509 Agreed. The bullet actually becomes too long, in a sence that sectional density exceeds modern air rifle capabilities forcing you to crank up the pressure. Gyroscopic stability is fairly simple to calculate, it's the dynamic stability that i don't understand how to calculate. Having a cavity in the back vs front ( reducing SD to acceptible levels) has an effect as well, just not clear on how to calculate it. Anyway...looking forward to your future research! Thank you for sgaring!
Most 22 Lr that I have pulled have truncated spherical heels
I subscribed even though I’m more of a shoot and measure guy. I sent this to my math centric friend.
Great work.
You must write and publish. Please.
With the designs that have a steep increase in drag as it goes supersonic, it is possible to take advantage of this to reduce vertical dispersion at long range. It is sometimes called "Mach trimming". The bullet is loaded to just above the critical mach number. This way, the bullet reliably slows to its max subsonic speed soon after leaving the muzzle. Believe it or not, this often produces more uniform bullet speeds downrange than trying to launch each round at precisely the same (subsonic) muzzle velocity.
@@jfess1911 I have heard of this, but given how the speed of sound varies with conditions, it would seem like something only an air rifle could hope to do consistently, and it would be a pain to keep adjusting the muzzle velocity, which would also change the ballistics. Life is too short for this.
@@jamesconger8509 Bryan Litz has some interesting articles on Mach Trimming. He did quite a lot of radar testing on it. There is also a video here on YT with him being interviewed about it. You are right that it is.a pain to match the bullet to the speed of sound for changing conditions.
One interesting point he brings up (along with high-speed photos of a shot 22 bullet) is that the shape of a fired .22 bullet is not the same as an unfired one. A photo of the bullet leaving the muzzle shows no heel section. It has obturated inside the bore to match the shank diameter.
@@jfess1911 Thanks. That implies that the sims I did for the no-heal case might actually reflect the bullet as fired. The shape of the drag curve was the same, so the same approach applies.
@@jamesconger8509 That video interview is on the Ultimate Reloader channel, if you want a look. The photo is shown there. There are also a couple short ones on Litz's Applied Ballistics channel.
Litz stated that none of the existing ballistic curves do a great job of matching the 22 LR trajectories he saw with the radar.
Now that I have looked farther into it, I agree that Mach trimming seems impractical. It looks like you might need a barrel with numerous ports drilled along its length that could be covered and uncovered to produce the perfect velocity from a batch of ammo
.
I have a silly imagination and pictured a sliding trombone-like device attached near the chamber tap off the desired amount of gas. Yes, I know it is ridiculous, but the image in my head is pretty funny!
1: Isn't there a partial vacuum behind the bullet?...
2: Is it possible for the bullet to create a vapor or condensation trail behind in a humid environment?
3: Could a motion pucture camera operating at 42 frames per second capture that trail before it evaporates?
I don't know. There is a little low pressure region right behind the bullet, but the wake is also heated up by the bullet's passing, which would tend to make any mist evaporate. I've shot in 100% humidity and never noticed a vapor trail, but that doesn't mean it can't happen.
@jamesconger8509 : Thanks. I mention it as there's a famous photo of a streak photographed passing Trump's head. And a certain frame of the Zapruder film of JFK's assassination wherein a streak appears passing behind the driver's head as the President's head is hit.
4:09 The velocity of air rises to above 0.73M around the ogive, lowering the temperature. As it reaches the heel, velocity drops (skin drag is a contributor), temperature and pressure rise. Subsonic diffuser flow conditions. I don’t think you included internally generated heat into your simulation, so the bullet temperature is probably not the cause.
He's not old enough to be my grandpa but it felt like " come er young fella and let me teach ya how amazing this thing is."
The heel obturates and fills the bore entirely once fired, we recovered several after I broke my last record with them at 1325 yards.
@@jamesstewart9970 Yes, several people have mentioned this. The no heel case might be the base case.
Interesting, thank you.
I adjust my speed in the kestrel to match the real bullet flight out to 200 yards regardless of what my chronograph says. I just use the chrono to identify flyers/ES outliers while im getting dope. After 200 I adjust the AB 'drop scale factor' in the kestrel. G1 also works well but i really like how easy the DSF feature makes it to get a good dope card. Loved the video thank you for the lesson.
I think the reason this works for you is that you are working around the poor fit of the G1 model by adjusting the muzzle velocity. Try using the G7 model with a BC of around 0.069 and the measured muzzle vel. I think you will find it fits the data better. BTW: I used to do exactly what you are doing.
I'll give it a whirl and see how it goes!
As a pilot... i appreciate the applied aerodynamics on the bullet shape
That's my bias too. Most of my time is in gliders.