Best video explaining an alternative explanation to the usual reasons given for the dreaded problem of pellets spiralling. Thank you so much for all your efforts
Gregor Kamenšek hello sir, is it possible to show us on video a slow-mo travel of a .22 cal pellet ( jsb 18gr for example) at 100 yards using the rti barrel or the new 1:32 barrel? Im curious how well it groups.. if most airgun enthusiast see this on youtube, i believe you can easily sell Rti priest and the new prophet..
Gregor, Being a fellow EE, I can appreciate your quest for knowledge and understanding. Thank you for taking the time and effort to share. Looking forward to your future adventures.
Thank you for your interest in sharing your knowledge. I feel I have solved some of my doubts. I believe your video will make me a better shooter. Greetings from Portugal
Excellent explanation! So probably this is why shorter pellets tend to spiral on lower velocities, shorter pellet means weaker drag stabilization (centers of pressure and mass are closer together) and in that case in downrange pellet orientation doesn't follow the flight direction as it should...
Hm, that might be the case but I would assume that bigger effect plays the fact that shorter pellets are also lighter and therefore more prone to destabilization. In my experiences though, a lot of longer and heavier pellets have more problems with high velocities than the short lighter (sometime). For example, JSB King in the barrels I tested (standard LW) can take up to 290 m/s bit the longer and heavier Kink Heavy can only reliable go up to 275 m/s and the MK2 even less. I do agree that the momentum created on shorter pellets by drag/flare is smaller but shorter/lighter pellets also need less force to correct their trajectory so I am not sure what play a bigger role here. Sorry but I do not have a definitive answer here.
@@gregorkamensek3923 I forgot to mention that I mean comparing shorter and longer pellets with same weight, so the destabilization can't come from the less mass. JSB King Heavies are very good example, shorter MKII pellets go easier to spiral on higher speeds because they have less momentum from drag compared to longer ones. Additionally on downrange rotation of pellet is lost very little, almost none, but the drag is reduced by squared velocity, so the resistance of the pellet direction to follow the trajectory is even more prominent on shorter pellets (with same mass as longer). In my option every pellet go spiral below some speed and that speed I think has something with dominance of rotational stability over the drag stability.
Great explanation about this problem some shooters have ! I have 2 Weihrauch 77K in .177 and .22 cal. and tuned those down to sub 12 fpe because FT shooting. What I´v found out is , the .177 do not like 10.3 gr JSB´s anymore wich was my preferred pellet at 18 fpe So ...Physics are all over the place !!!!!! Thanks for sharing and bring us closer to the "medium" !!
You are a very smart man I have to say. I in joy your video and you English is really good. I have been waiting your video for some time now enough to say your English is really clean now 👍👌✌️💯
Perfect answer for my problem, thanks :) Some months ago I installed nitro piston into my hungarian made FÉG LG42 airgun (.22). The velocity increased, pellet turning speed increased and that went out from the barrel unstable :( I will try with slug, but I think the final solution will be to reinstall the spring.
Great explanations! I would like to hear your take on how the arched path for longer shots introduces another set of angle changes initiating more destabilization.
Very nicely explained, Gregor, despite English not being your native language. You did a good job explaining why higher twist rates can make a pellet that is not pointed straight spiral. It would be interesting to talk more about why two barrels with the same twist rate might have different results. How differences in the silencer, the crown and other variables might be a factor causing the pellets to tilt.
You are right, that would be a good topic too, right now I am preparing to go more in depth in the PCP airguns them self, so next video, will probably be about regulators...
Good stuff as always 😄 Barreltwist and velocity is one part to go long range, projectileweight and shape another. The most ballistic shape for what barreltwist.... The milliondollarmystery 😊 And i belive that a slug coated with plastic could increase speed a lot. And is known that ligter pellets go faster. Finding the ideal bullet/weight/speed/barreltwist has always been the enigma for airgunners. In gunpowder ammo the sabotbullets increased speed. With airguns, sabots i belive is not the best solution due that it missing out on 1500 fps. Coated bullets will for sure do that increase of speed. Have a nice day and keep your good vids comming.
Hi Gregor , thanks for ur input. One of the important Airgun subject is the projectile of Pellets and Slugs in conjunction with its grain weight and air push in PCP and semi auto AirGuns? Love if u can explain that too😀
This why FX "smooth twist" works so well in conjunction with an effective air stripper. Even at long ranges. The effective twist rate on these older FX barrels was 3 to 4 feet...
Yes...my mind is eating this brain candy up. Thank you. If you wouldn’t mind since you brought it up, yes, a video on transfer ports and valving working together. Most of the air guns I have modified are made in China. They came with ok power but after drilling out the transfer port and turning down the size of the valve, these guns have become quite powerful. Upping regulator pressures or lowering regulator pressures while increasing plenum size is another effective way for power and efficiency that could be brain candy. Thank bud. Love your videos. Take care.
I will definitely cover TP, plenum size, valves, regulator pressures,... I just don't know yet how to split the videos as all of those topic are related but they are probably too long for one video...
Very good and informative, keep them coming. Does that mean that slower rate twist is always better even at slower velocity? What about Airgun slugs ? Where do they fall in this bind .
Not necessarily. It depends on RPM, so for solver velocity, you can use slightly higher twist (standard 1/18" is more than enough) otherwise the gyro effect will almost not exist and you do need some for that first few inches /cm of pellet flight. It also depends on how far you are shooting, it is close range, higher RPM will be better usually.
Thanks , Its a good one, Because of you I am down to buy one of the first Prophet to hit the USA in 25 caliber, I have held off buying the troubled Impact from FX just to many problems (o rings) , I have followed the RTI guns from the start and I do believe they are more of a K.I.S.S. gun, Thanks and make more videos, Mike
@@gregorkamensek3923 Yeah mine were kits too, but you had to assemble them. They are a Schluter, Scout 60, a Kalt Baron with a gasoline engine, and a Kyosho, Concept 30. They are probably considered antiques now. I haven't flown them for 3 years now. I mostly fly on the simulator now, way cheaper.
@@johnb5519 Yea, a mild crash with CP helicopter is almost the same as maximum crash....LOL. I think that everyone who flies a RC CP heli knows that it is 90% service and 10% flying (or even less).
Gregor, we would have been great neighbors. May of the same interest, the helicopter rotor system love it. Picked up my new SK-19 Semi-auto/Full-auto AirRifle last week.
very good explanation! started to loose me a little bit with the helicopter blades? but like your style of bringing it all together. please do a video on transfer ports vs. barrel Dia. and velocity
The So of Pellets Ok, the pellet is moving away from someone. The pellet is spinning clockwise - looking at it from behind. A force acts on the pellet skirt to move that point of the skirt toward the pellet center. Because of gyroscopic procession, that force is transferred 90° around the pellet skirt counterclockwise, and acts to move the/a skirt point toward the pellet center. That is, toward the pellet center of rotation. So the axis of rotation moves the same distance and direction as the skirt. The entire skirt moves the same. So the skirt moves off center. So the wind resistance acts on the opposite side of the skirt, which is now not in line with the pellet direction of travel, it is out in the wind. So the skirt is now continually moved in a smooth development, farther out of the line of travel by the wind resistance while the gyroscopic procession simply moves the wind resistance force 90° counterclockwise. So the momentum in the pellet increases the effects of these forces, causing the skirt to be moved increasingly farther away from the trajectory. Soon the pellet axis of rotation is being moved so far from its trajectory the head of the pellet is also moved away from the trajectory. By the wind. So those pattern effects feed on themselves and the entire pellet begins to wobble in a circle. That circle grows in a counterclockwise direction while the pellet rolls (spins) clockwise. It's 5 individual forces working on one item from different directions. Forward momentum. Wind resistance. Clockwise spin. An initial force on the pellet skirt. Gyroscopic procession. (The pellet decelerating because of wind resistance adds a millionth of a force helping increase the wobble, but we shouldn't mention it or the subject might get complicated).
hmm, My brain flipped out at how neat the helicopter was and I could not take that bit in. The oil filter was less interesting , and therefore I was able to comprehend that part. More likely I am a thick as champ, still every day is a school day. thanks Gregor.
wow so great greg very well exlplained and i gain knowledge much. so now i dont wonder y some my pellets fly away far from the grouping. that moment i was thinking that maybe some pellets are not perfectly correct made. of course there is always one pellets are incorrect centrifugal or i mean its not balance on side to side.. while on the moment of molding from factory.like for example the rim tire of motorcycle bike there is tiny metal thing attach on one side just to balance the weight on opposite side .for some reason that it was not perfeclty equal in centrifugal weight. but dont take my word coz its just my own opinion ..not really hundred percent sure if im right. but still im hoping to contribute some idea ...
Yes, that is one of the reason that the spiraling effect can occur but I wanted to focus on why the spiraling is progressive and the direction is in the opposite side twist direction... BTW: match grade bullets for firearms are actually tested for center of gravity similar than a tire of a vehicle...:)
This is great and I am looking forward to future videos in the series. I thought the helicopter analogy was confusing as you have to introduce concepts from the analogy. I would be interested in the math of how caliber, speed, twist rate and mass of pellet is related to destabilization. The gyroscopic stabilization, you said, is required to overcome the destabilizing force of the back pressure at the muzzle.... but that distance is very short compared to distance to the target so to me this explanation doesn't makes sense. Is there an optimal number of revolutions for the projectile to complete before it hits the target? Switch rate and distance are obviously factors here. Rotation would also cancel out effects of an uneven mass distribution, but I don't know if matters in the scheme of things in particular of the magnitude of uneven drag. Do slugs require lower twist rate only because of their relatively greater mass?
Spiraling diablo pellets is due to The Dzhanibekov Effect. As pellet spin it tries to flip over but cannot because airflow drag on its tail end is preventing it. But the farthest the pellet the slower it goes... the lesser the tail drag... the worse the spiraling. You can't stop this from happening. Because 1st nothings perfect: pellet shape, pellet mass distribution and 2nd most importantly a perfect pellet spinning vs pellet flight path: the more gyroscopic stabilization you have the more angle you'll have at longer range between spinning axis and flight path/airflow drag. Enough to initiate Dzhanibekov Effect... Airflow drag prevent it at beginning of flight but... initiate it at some point toward the end... You can only mitigate it using: 1 - diablo pellet with higher (diameter/length) ratio (for a given caliber it means using shorter pellets) 2 - or lower twist rate. This is logic remember: given a caliber heavier pellet are longer... which in turn need faster twist rate... for bullet shaped slugs not diablo one! czcams.com/video/Xrf1HzFJ8jc/video.htmlsi=9SSY4AG0boOzVt26 czcams.com/video/1VPfZ_XzisU/video.htmlsi=7UcEdvh0DZyLdOt_
Actually, that is not true. Pellet and slugs have only 2 axis of inertia. Although you could claim the imperfections are the way they get three axis, then the slugs would have same problem as pellets. The very point of this video is the corelation of drag (or flare as some preferred to call it although the momentum derives from drag) and spin stabilization (gyro) stabilization. Both of these two are only present in shapes like pellets at the same time and the problem is that although flare is only dependent of the airflow, the gyro is not, it is actually dependent of derivative of the projectile movement and causes 90° force to the momentum it is caused by. This is best demonstrated by the fact that the spirals are ALWAYS in opposite direction of the pellet rotation. Just think about how weird that is :) You are right that the issues needs a "trigger" and that trigger is imperfection of the projectile (or a ever so slight wooable at barrel exit). That is the initial condition that is required, same as with Dzhanibekov Effect.
@gregorkamensek3923 At 9:55 czcams.com/video/1VPfZ_XzisU/video.htmlsi=OF1cslT15F_PuGV1 But well... indeed, you have the full right to believe in whatever you like! Have a nice day.
Thank you for this. I love brain food and this really helped me understand this issue much much better. I have a completely different outlook on this matter now and I have no doubt others will also. Very helpful. Oh, by the way, the LCS SK-19 and the Huben have a completely different trigger group altogether. I wish I could send you a picture of mine I have on my phone. Mine gun stopped firing suddenly after 6000+ rounds and was sent back. The action is similar if not the same as the Huben but that’s about it. I don’t know if that’s a good thing or a bad thing because I don’t have a Huben yet, plus 5000 psi is a heck of a lot of pressure and my compressor is only rated for 4500 of which I only fill to 42-4300 on a fill. Being that the Huben is regulated wouldn’t matter with a lower psi fill but still would get less shots at a lower pressure. Anyway, just wanted to let you know they are a little different.
Thanks for the info. Yeah, the trigger has to be different as LCS also has full auto. There is not simple mod that would enable K1 to have it so it makes sense that the trigger cannot be the same design.
Unfortunately this video is based on a completely wrong assumption. Pellets are not drag stabilised, never have been and never will be unless someone ties a parachute or ribbon on the back of their pellet. Pellets are flare stabilised and flares stabilise by producing lateral stabilising aerodynamic moments about the CG, not through drag. If the pellet was travelling at around 6000ft/sec then there may well be a drag stabilising moment but subsonic aerodynamics simply do not work as described in this and other videos purporting to describe pellet stability (the one recommended by Gregor contains more than 20 mistakes at my last count, some of which are major completely misleading mistakes). The centre of pressure on any projectile is associated with lateral forces, drag makes next to no contribution to its position relative to the CG. As a simple test perhaps the drag stabilisation proponents can explain why projectiles with cylindrical bases are apparently not drag stabilised when the base drag on them is much higher than the drag on the front when it is streamlined, just as it is on a pellet. Alternatively, wadcutter pellets have most of their drag on the front and should therefore according to the drag theory be unstable but they are not, why is that? All that is being described in this video is the basic gyroscopic reaction to a lateral moment about the CG, nothing to do with drag. Gyroscopic stability relies on this reaction and without it nothing would ever be gyroscopically stable. The reason pellets spiral is through a loss of dynamic stability leading to dynamic instability and an increase in yaw angle rather than a decrease when the pellet is dynamically stable. It is all tied in with the ratio between the pellet spin rate and its forward velocity, it is changes in this which produce dynamic instability. So why should anyone believe me rather than the video? Maybe because I spent almost 40 years working exclusively on the external ballistics and aerodynamics of gun launched projectiles having been trained in aerodynamics and ballistics.
Hi. I appreciate your input. I have studied it and I understand it and you are correct in using the wrong terminology for the force that is trying to keep the pellet flying straight (flare instead of drag). Interestingly enough, everyone is using the work drag stabilization for pellets; I have only found a few that uses flare stabilization and this was not that I am aware of this term. However this does not much for the base of this video as the force of drag would act in the same direction as flare force does and the result in this case is the same (it is trying to get the pellet orientation facing the pellet head in direction of the flight). As mentioned the beginning of the video, I am not a physicist nor English is my native language, so terminology mistakes are bound to happen. In any case, I will correct this in the next video (the video itself will be about different topic though). Since you seem to be interested in the topic (related to airguns), I would encourage you to make your own videos or at least contribute your knowledge to airgun community. We would desperately need people that understands this, possible better than me :). There are tons of material on the firearm projectiles and supersonic flight but very little to none about subsonic airgun projectiles.
@@gregorkamensek3923 Thanks for the reply. Your English is fine do not worry about it, I am sure it is much better than if I tried to talk in your language. I write on a number of forums under the label Ballisticboy, mainly the GTA forum, the UK Airgunforum and the UK based Shooting the Breeze forum. I have recently put an explanation on pellet stability and the different types of stability on the GTA forum. It attempts to explain that drag plays little to no part in pellet stabilisation and that it is lift forces at right angles to the drag, produced by suction on the side of the flare, which produce correcting moments. The whole reason why flares are used is because they produce a stabilising lift moment as predicted by slender body theory and stability is all about moments about the CG, not forces. The vasy majority of the drag force cannot produce any moment about the CG. As for making a video, if I did everyone would be asleep after the first couple of minutes. It is a pity as I have a simple device incorporating a freely moving flywheel made for me by the late Gerald Cardew, an airgun pioneer, which demonstrates very simply how gyroscopic stability works.
@@milesm1465 I agree with you an all parts, including the one about most people falling asleep as this was my main concern when going in this video, so you might be surprised by response as I was :). I would love to see the freely moving flywheel, I am sure that it looks way more convincing than my ball-baring spinner. LOL
Gregor, do bullets have higher (faster) twist rates and is that a good thing for bullets? For example, what is the average twist for a .22 rim fire rifle? Also, do large caliber center fire rifles, eg. .308 have the same twist as a .22 rim fire?
Yes, generally barrels for bullets have faster twist rate than barrels for pellets. The required twist rate for bullets depends on many parameters like caliber, bullet length, velocity,... So here are some examples: standard airgun barrel has approx 1:18" twist, standard .22 LR barrel has 1:16" or even faster, typical 308 has 1:12". Typical rule is: the longer the bullet the faster twist is required, the smaller the caliber again faster twist is required...
Hello, congratulations for the video. I'm going crazy, because my cricket tactical carbine 2 in 5.5mm at 50 meters with JSB of 18.13 group well (880 FPS); but, with 25 grain, it makes that "spiral" and I CANNOT CORRECT IT. From your video I have a better idea of what I should do. What do you recommend, increase or decrease speed? Thank you.
Are you using Monster Redesign? Those should be stable... Standard .22 LW barrels (and also other like CZ) are in my experience very prone to make the pellets spiral. Poly barrels are much better in this regard. But in any case, lower velocity is usually better although you are already quite low I imagine so I am not sure they will solve the problem.
That depends, I assume that you are talking about pellets since this video is about pellets. If I would have to set a threshold for what is high velocity, I guess I would say everything above 950 fps. Here is an example. RTI long range barrel uses 1:32" twist and at the EBR, I was shooting Monster Redesign at about 1040 fps. At these velocities, the probability that the transonic air around the pellet is higher (compared to typical "regular" velocity) but there are definitely no spirals caused by the effect described in the video that would most likely appear with regular twist barrels. All I am trying to emphasize here is what is the reason for pellet spirals and not every pellet will behave the same and there is a definite limit of the pellet shape and sectional density that limit the optimal velocity but in competition where the use of pellets in mandatory (like EBR), one of the very important things is to be able to shoot with as high velocities as the accuracy allows it simply because the shooting takes place in outdoor environment.
Hi Gregor In my Edgun Matador cal.30 Super long, from time to time I see how the pellet makes this turn ..... same shot 30 times, and the shots are good and the next shot 31 does this ?? I have tested at different speeds 270ms, 275ms, 280ms, 285ms, etc. and it is always the same You already tell me what you think since you have an equal to mine. B, regards
nice vido ,bro , i learn more about airgun and pellet now ， thanks for sharing . how about slug ? it will also spiral as pellet too ? i am interested in slug , it have better BC and is good for long range shhooting Looking forward to your more videos ）））
@@gregorkamensek3923 So what causes spiral for slug? I watch Matt's video about slug, and I think it may be related to muzzle velocity. 950FPS or highermuzzle velocity will have tighter groups
you say pellets need fast twist rates, but FX after many tests discovered that slower twist rates are better for pellets and faster twist rates are better for slugs,. thats why the FX pellet liners are 1:28 and the slug liners are 1:20
Better way of saying would be that this 90° difference of cause an effect between those two stabilization causes an oscillation because a positive feedback loop is presented and any minor starting deviation from perfect axis alignment of pellet and flight path is amplified with time (or length of flight) due to those positive feedback loop.
Thank you Gregor, I've been waiting for this kind of series from someone that can explain it without the math ( maybe a little ). I have a question; is it possible to tune a pcp to a particular pellet for accuracy, ie after sorting for size and weight, If I have a lot of one type of pellet. Don't want to waste them. Again thank you.
If the pellet size is appropriate for the barrel and the pellet design is good (meaning that the pellet is capable of accurate flight), then probably yes. But the problem is that if the reason for lack of accuracy is too high spin (twist), you will simply need to shot it at lower velocity or get a barrel with slower twist rate.
@@gregorkamensek3923 Thanks for reply. What twist rate and speed would you suggest for 10.33 Gn .177 Diablo out to 50m for best accuracy. I realise theres more to it than twist rate and speed, but as a starting point. Regards Peter
The only way to find the best air pressure, hammer spring adjustment and muzzle velocity combination for the best accuracy is to test...a lot. Start at a low air pressure (if regulated) and hammer hit and slowly increase the pressure and when that stops the fps increase add more hammer spring until fps stops increasing, then add more air pressure etc, etc, etc. Shoot 5 shot groups at each setting and you will see them hit all over except at one combination - that's the one. Be prepared to shoot a lot of pellets. Weighing and head sizing helps. Eliminate the light and heavy ones. Then find which head size works best in your gun and test with these.
@@james1795 I have a benjamin maximis .177 the rifle shot the jsb 13gr pellets will at 830 fps. Tomorrow I will be testing different pellets slugs and different velocities. I also have a hatsan nova. 177 and it doesn't shot any pellets will only the 21gr nsa slugs @ 880 fps. I believe the benjamin maximis has a 1:26 twist rate. The twist rate is slow for slugs but it may be good for pellets.
@@airgunsofidaho4886 I don't have a Maximis. But testing some of my .177s I get the best groups with H&N Baracuda Match also sometimes even better groups with the Beeman Kodiak Match. Both are 10.65gr and made by H&N only in different dies. Keep in mind these .177s are made in different diameters to choose from which can make or break the "perfect" group we like to see.
@@airgunsofidaho4886 Just to add. If you are getting 830fps out of the 13gn, a 10.65gn will be coming out hot, maybe not too hot to lose stability, but something to keep in mind.
You mean longer thane 600 mm?. I have actually used about 660 mm in my first videos with K1 and I also had an idea to modify one K1 with about 750 mm barrel but I don't know if I will actually do it...
Ok I'm at 3:19 and i swear i haven't seen your video before. I'm going to guess that why you say pellets spiral is something similar to why at low speeds of a centrifuge one can get away with inaccuracies of the tubes not being weighed out correctly but as soon as one increases the speed, say to getting up around several g; several things will happen (maybe even quickly LOL One is the centrifuge will begin to vibrate like hell, it may even move off the bench if it is indeed a bench mounted one then you'll be blown up by your boss if your not the boss of the lab and finally if not stopped by an automatic cut out you could have a serious accident depending upon the speed. So I'm thinking that since in reality airgun pellets are not exactly symmetrical or at least they can be easily made non symmetrical by clumsy fingers or just come that way and hence the rotational axis can easily be off centre. Ok there O've said it LOL. I'm not a ballistics guy nor an engineer but some crazy scientist LOL. Now I watch more!
Yes, that is let's say the initial reason for issues that everyone thinks off but as you have probably seen from the video, I wanted emphasize to the relation and cause / effect of a dual stabilization any why this problem progresses... Also, based on this theory the RTI long range barrel for pellets was developed that has amazing results with pellets as close to sonic speed.
Yeah after I watched your video i checked out their site. Amazing looking for sure. Would love to have one but maybe it could be divorce if i did LOL Thanks for the feed back!@@gregorkamensek3923
Just a minor correction. You mention in your excellent video that a bullet stabilizes due to “angular precession.” I do not believe this 100% correct. Consider this small summary of physics 1.0.1. below: In physics, angular momentum is the rotational equivalent of linear momentum. Like linear momentum, angular momentum is preserved. In practice that means angular momentum of a linear moving particle (f.i. a bullet) has a “pseudovector” (read direction) which is also conserved; i.e. remains constant. This is why a pellet or bullet spinning around its longitudinal axis keeps pointing in the same direction. Precession is a change in the orientation of the “pseudovector” of a rotating body (but not “nutation”). Precession can be caused by external forces AND/OR without any external forces (torque free precession). This effectively means, all spinning particles (bullets) are subject to precession, “wobbling” (but not “nutation”). The most important thing here is that in practice (and theory) the conservation of angular momentum causes bullets to fly straight. Not angular precession. P.s. “Nutation” is, more or less, non-contant precession.
Thanks for the input. I really appreciate this kind of comments! Hm, I have to be honest, I checked the word "nutation" before I began forming the answer despite the fact that I know the word but I wanted to make sure I know the correct meaning. You are right that nutaion can be the cause for bullet wobbling but tis (from my understanding) is purely based on the fact that the center of mass in not it the longitudinal axis of the bullet or if the bullets shape is not symmetric and the air friction (drag causes) this wobble. But you are right that if you think about it, the bullet just creates an axis of the angular momentum that is unlike in the with the pellet not changing direction. I should have put this in the video :). That is why I like this kind of videos as I get a chance to learn more :). Thanks!
Gregor Kamenšek : I am glad I was able to assist! For the avoidance of doubt, your explanation why pellets “spiral” and other explanations are fully correct. I just thought it would be useful if the correct terminology is used; Conservation of Angular Momentum: The cause why spinning projectiles fly straight (in vacuum), Precession: The “wobbling” of projectiles with a 90 degree phase shift caused by “fluid-dynamical” disturbances (a change in the “first Euler angle”) and Nutation (Latin for “Nodding”): Variations in Precession, caused by a change in the “second Euler angle.” As I stated above, I believe you are correct in that Precession causes the spiraling of pellets. But due to the fact that projectiles move in 3 dimensions, rotate around 3 axis, have imperfections in their internal consistency AND the influence of “fluid-dynamics” makes mathematical modeling of the flight of pellets extremely difficult. Perhaps a nice subject for a PhD dissertation, but hardly interesting CZcams material...;-) Looking forward to your next CZcams video!!!
oh yes greg so ur also up into 3d heli hobbie... i think u also know how to invert fly tricks haha. anyway regarding the heli blades the term use to call when blade shifting down and up is called pitch. pitch propeller . negative pitch and positive pitch. that was driven by swashplates.
Yeah, I used to be... But I don't practice anymore and I would not dare to invert the heli anymore. In my "best" days I quite confidently inverted it but I definitely did not know to do any 3D tricks... Yes, correct it is called pitch and these helis are called collective pitch because the blades RPM is constant (Governor mode) and only the pitch determines lift and controls...
@@gregorkamensek3923 haha and its very expencive hobbies ... the more u having fun about the tricks the u spent thousand of money and i stop this hobbies by looking for some another hobbies that is not so expencive hehe. better go into drone hobbies and aerial video much better ...its not that expencive and very entertaining.
@@gregorkamensek3923 hellow greg hows it going...? i bet u know the lcs sk19 semi full auto? how u compare that pcp to huben k1? which one is best for longrange? and also how u compare the fx impact to huben when it come to longrange. knowing that the impact has the lower power in footpound energy... but ive seen some utube vlog that the impact mk2 reach the 415yard shoot. but that is maybe bigger caliber
This video is pure gold. I watched the original one from M.D. but he wasn't even near your deepness and knowledge.
Thanks. I appreciate it!!!
Dear Gregor, I admire the way you explained with simple words and clarity the subject in your video.Keep up the good work! :)
Best video explaining an alternative explanation to the usual reasons given for the dreaded problem of pellets spiralling.
Thank you so much for all your efforts
Thank you all, I really appreciate comments and pozitive response.
Gregor Kamenšek hello sir, is it possible to show us on video a slow-mo travel of a .22 cal pellet ( jsb 18gr for example) at 100 yards using the rti barrel or the new 1:32 barrel? Im curious how well it groups.. if most airgun enthusiast see this on youtube, i believe you can easily sell Rti priest and the new prophet..
@@briango7489 Yes, I will definitely have a video that shows this.
Thank you for explaining part of the physics behind airgun shots , spaciba 👍
Really interesting, Gregor. Keep'em coming. please. Already looking forward to your next one.
Please bring those videos asap, you are spot on with the physics.you have explained it beautifully.
Gregor, Being a fellow EE, I can appreciate your quest for knowledge and understanding. Thank you for taking the time and effort to share. Looking forward to your future adventures.
You did a good job explaining this, looking forward to your next video.
yes keep them coming ,great video Greg.
Excellent video. Thanks for sharing your knowledge good man.
Congratulations on your win.
Thanks for taking the time to explain these issues.
God bless you brother.🍺🍺🍺🎯🎯
Matt Dubber sent me here!!!🍺🍺
Thanks:) Matt's video is excellent as well.
Please continue, I am sure we will all appreciate to learn more! Thank you.
What a clear & concise explanation on it! good job!!!
I'm getting more into this gyroscopic movement of pellets, all the vids on this are very interesting.
Thanks for posting.
Thank you Gregor, for this great video. I also want to thank AirArmsHuntingSA for recommending your channel to explain this subject.
I understood everything and all does makes sense..pls continue making informative videos..thank you
Thank you for your interest in sharing your knowledge.
I feel I have solved some of my doubts.
I believe your video will make me a better shooter.
Greetings from Portugal
The way you explain these matters is excellent. I have now a better understanding of ballistics.
Excellent explanation!
So probably this is why shorter pellets tend to spiral on lower velocities, shorter pellet means weaker drag stabilization (centers of pressure and mass are closer together) and in that case in downrange pellet orientation doesn't follow the flight direction as it should...
Hm, that might be the case but I would assume that bigger effect plays the fact that shorter pellets are also lighter and therefore more prone to destabilization. In my experiences though, a lot of longer and heavier pellets have more problems with high velocities than the short lighter (sometime). For example, JSB King in the barrels I tested (standard LW) can take up to 290 m/s bit the longer and heavier Kink Heavy can only reliable go up to 275 m/s and the MK2 even less. I do agree that the momentum created on shorter pellets by drag/flare is smaller but shorter/lighter pellets also need less force to correct their trajectory so I am not sure what play a bigger role here. Sorry but I do not have a definitive answer here.
@@gregorkamensek3923 I forgot to mention that I mean comparing shorter and longer pellets with same weight, so the destabilization can't come from the less mass. JSB King Heavies are very good example, shorter MKII pellets go easier to spiral on higher speeds because they have less momentum from drag compared to longer ones. Additionally on downrange rotation of pellet is lost very little, almost none, but the drag is reduced by squared velocity, so the resistance of the pellet direction to follow the trajectory is even more prominent on shorter pellets (with same mass as longer). In my option every pellet go spiral below some speed and that speed I think has something with dominance of rotational stability over the drag stability.
You made it crystal clear thanks
This is great as a new air gunner this info is really benefitial, thanks
Great explanation about this problem some shooters have ! I have 2 Weihrauch 77K in .177 and .22 cal. and tuned those down to sub 12 fpe because FT shooting.
What I´v found out is , the .177 do not like 10.3 gr JSB´s anymore wich was my preferred pellet at 18 fpe So ...Physics are all over the place !!!!!!
Thanks for sharing and bring us closer to the "medium" !!
Very good dissertation on the subject!!! Thank you for your presentation.
This was an excellent explanation and I thank you for sharing your knowledge.
You are a very smart man I have to say. I in joy your video and you English is really good. I have been waiting your video for some time now enough to say your English is really clean now 👍👌✌️💯
Superb explanation. Thank you !
Wow! Very well explained!
Interesting, a new look at airgun ballistics ..!
Perfect answer for my problem, thanks :)
Some months ago I installed nitro piston into my hungarian made FÉG LG42 airgun (.22). The velocity increased, pellet turning speed increased and that went out from the barrel unstable :( I will try with slug, but I think the final solution will be to reinstall the spring.
Pretty nice content and clear. I love physics
Great explanation.
Excellent video Gregor. Looking forward the whole serie. Greetings ✌
Informative video.
Thank you, my friend. 🙏
Ok just watched it great explanation, u got a subber.
Thanks :)
Great explanations! I would like to hear your take on how the arched path for longer shots introduces another set of angle changes initiating more destabilization.
Yes, that would be a good topic as well... I will consider it for a future video.
Very great and informative video, thanks a lot sir
Thought provoking. I begin to wonder about the high and low RPM's affecting trajectory drag...
More stuff to keep me awake at night :>)
Very nicely explained, Gregor, despite English not being your native language. You did a good job explaining why higher twist rates can make a pellet that is not pointed straight spiral. It would be interesting to talk more about why two barrels with the same twist rate might have different results. How differences in the silencer, the crown and other variables might be a factor causing the pellets to tilt.
You are right, that would be a good topic too, right now I am preparing to go more in depth in the PCP airguns them self, so next video, will probably be about regulators...
Good stuff as always 😄
Barreltwist and velocity is one part to go long range, projectileweight and shape another.
The most ballistic shape for what barreltwist....
The milliondollarmystery 😊
And i belive that a slug coated with plastic could increase speed a lot. And is known that ligter pellets go faster.
Finding the ideal bullet/weight/speed/barreltwist has always been the enigma for airgunners.
In gunpowder ammo the sabotbullets increased speed. With airguns, sabots i belive is not the best solution due that it missing out on 1500 fps.
Coated bullets will for sure do that increase of speed.
Have a nice day and keep your good vids comming.
Mind blown... great video!
Excellent- it all makes sense now, thanks :)
Great! Keep the videos coming Gregor!
Nice explaining, i have to slow my aselkon down again, got bad spiraling when going to high pressor( 150 Ba )
Hi Gregor , thanks for ur input. One of the important Airgun subject is the projectile of Pellets and Slugs in conjunction with its grain weight and air push in PCP and semi auto AirGuns? Love if u can explain that too😀
Well, considering my show pase, I sure hope I will get to this topic as well... :)
Thanks, very cool!
Seveda Gregor, keep up the good work. Zelo poučno in zanimivo.
This why FX "smooth twist" works so well in conjunction with an effective air stripper. Even at long ranges. The effective twist rate on these older FX barrels was 3 to 4 feet...
Yes, very true.
Yes...my mind is eating this brain candy up. Thank you. If you wouldn’t mind since you brought it up, yes, a video on transfer ports and valving working together. Most of the air guns I have modified are made in China. They came with ok power but after drilling out the transfer port and turning down the size of the valve, these guns have become quite powerful. Upping regulator pressures or lowering regulator pressures while increasing plenum size is another effective way for power and efficiency that could be brain candy. Thank bud. Love your videos. Take care.
I will definitely cover TP, plenum size, valves, regulator pressures,... I just don't know yet how to split the videos as all of those topic are related but they are probably too long for one video...
Very good and informative, keep them coming. Does that mean that slower rate twist is always better even at slower velocity? What about Airgun slugs ? Where do they fall in this bind .
Not necessarily. It depends on RPM, so for solver velocity, you can use slightly higher twist (standard 1/18" is more than enough) otherwise the gyro effect will almost not exist and you do need some for that first few inches /cm of pellet flight. It also depends on how far you are shooting, it is close range, higher RPM will be better usually.
Thank you very good video
yes , more !! , thank you for the video ;)
Thanks , Its a good one, Because of you I am down to buy one of the first Prophet to hit the USA in 25 caliber, I have held off buying the troubled Impact from FX just to many problems (o rings) , I have followed the RTI guns from the start and I do believe they are more of a K.I.S.S. gun,
Thanks
and make more videos,
Mike
Great explanation of a complex bit of physics. Interesting to see you are into model helicopters. I still have my old ones from over thirty years ago.
You probably build it yourself then, this is a HK kit...
@@gregorkamensek3923 Yeah mine were kits too, but you had to assemble them. They are a Schluter, Scout 60, a Kalt Baron with a gasoline engine, and a Kyosho, Concept 30. They are probably considered antiques now. I haven't flown them for 3 years now. I mostly fly on the simulator now, way cheaper.
@@johnb5519 Yea, a mild crash with CP helicopter is almost the same as maximum crash....LOL. I think that everyone who flies a RC CP heli knows that it is 90% service and 10% flying (or even less).
@@gregorkamensek3923 Yes, you are right about that.
Gregor, we would have been great neighbors. May of the same interest, the helicopter rotor system love it.
Picked up my new SK-19 Semi-auto/Full-auto AirRifle last week.
Nice :) Let me know how it works compared to Huben...
very good explanation! started to loose me a little bit with the helicopter blades? but like your style of bringing it all together. please do a video on transfer ports vs. barrel Dia. and velocity
no offense, i like your channel! Explains the physics of why a pellet makes spirals when shot at high velocities
Please continue with these series. I’m interested in valve spring pressure v reg pressure.
I will :)
very nice and informative video keep up the good work liked and supscriped and should have done that long time ago 👍🏻
The So of Pellets
Ok, the pellet is moving away from someone. The pellet is spinning clockwise - looking at it from behind.
A force acts on the pellet skirt to move that point of the skirt toward the pellet center. Because of gyroscopic procession,
that force is transferred 90° around the pellet skirt counterclockwise, and acts to move the/a skirt point toward the pellet center. That is, toward the pellet center of rotation. So the axis of rotation moves the same distance and direction as the skirt. The entire skirt moves the same.
So the skirt moves off center. So the wind resistance acts on the opposite side of the skirt, which is now not in line with the pellet direction of travel, it is out in the wind.
So the skirt is now continually moved in a smooth development, farther out of the line of travel by the wind resistance while the gyroscopic procession simply moves the wind resistance force 90° counterclockwise. So the momentum in the pellet increases the effects of these forces, causing the skirt to be moved increasingly farther away from the trajectory.
Soon the pellet axis of rotation is being moved so far from its trajectory the head of the pellet is also moved away from the trajectory. By the wind. So those pattern effects feed on themselves and the entire pellet begins to wobble in a circle. That circle grows in a counterclockwise direction while the pellet rolls (spins) clockwise.
It's 5 individual forces working on one item from different directions. Forward momentum.
Wind resistance.
Clockwise spin.
An initial force on the pellet skirt.
Gyroscopic procession.
(The pellet decelerating because of wind resistance adds a millionth of a force helping increase the wobble, but we shouldn't mention it or the subject might get complicated).
hmm,
My brain flipped out at how neat the helicopter was and I could not take that bit in.
The oil filter was less interesting , and therefore I was able to comprehend that part.
More likely I am a thick as champ,
still every day is a school day.
thanks Gregor.
great pls keep go
wow so great greg very well exlplained and i gain knowledge much. so now i dont wonder y some my pellets fly away far from the grouping. that moment i was thinking that maybe some pellets are not perfectly correct made. of course there is always one pellets are incorrect centrifugal or i mean its not balance on side to side.. while on the moment of molding from factory.like for example the rim tire of motorcycle bike there is tiny metal thing attach on one side just to balance the weight on opposite side .for some reason that it was not perfeclty equal in centrifugal weight. but dont take my word coz its just my own opinion ..not really hundred percent sure if im right. but still im hoping to contribute some idea ...
Yes, that is one of the reason that the spiraling effect can occur but I wanted to focus on why the spiraling is progressive and the direction is in the opposite side twist direction... BTW: match grade bullets for firearms are actually tested for center of gravity similar than a tire of a vehicle...:)
@@gregorkamensek3923 Are there easy ways to test diabolo pellets for their centers of gravity?
Thanks :)
This is great and I am looking forward to future videos in the series. I thought the helicopter analogy was confusing as you have to introduce concepts from the analogy. I would be interested in the math of how caliber, speed, twist rate and mass of pellet is related to destabilization. The gyroscopic stabilization, you said, is required to overcome the destabilizing force of the back pressure at the muzzle.... but that distance is very short compared to distance to the target so to me this explanation doesn't makes sense. Is there an optimal number of revolutions for the projectile to complete before it hits the target? Switch rate and distance are obviously factors here. Rotation would also cancel out effects of an uneven mass distribution, but I don't know if matters in the scheme of things in particular of the magnitude of uneven drag. Do slugs require lower twist rate only because of their relatively greater mass?
Goog info keep it on👍
Spiraling diablo pellets is due to The Dzhanibekov Effect. As pellet spin it tries to flip over but cannot because airflow drag on its tail end is preventing it. But the farthest the pellet the slower it goes... the lesser the tail drag... the worse the spiraling. You can't stop this from happening. Because 1st nothings perfect: pellet shape, pellet mass distribution and 2nd most importantly a perfect pellet spinning vs pellet flight path: the more gyroscopic stabilization you have the more angle you'll have at longer range between spinning axis and flight path/airflow drag. Enough to initiate Dzhanibekov Effect... Airflow drag prevent it at beginning of flight but... initiate it at some point toward the end...
You can only mitigate it using:
1 - diablo pellet with higher (diameter/length) ratio (for a given caliber it means using shorter pellets)
2 - or lower twist rate.
This is logic remember: given a caliber heavier pellet are longer... which in turn need faster twist rate... for bullet shaped slugs not diablo one!
czcams.com/video/Xrf1HzFJ8jc/video.htmlsi=9SSY4AG0boOzVt26
czcams.com/video/1VPfZ_XzisU/video.htmlsi=7UcEdvh0DZyLdOt_
Actually, that is not true. Pellet and slugs have only 2 axis of inertia. Although you could claim the imperfections are the way they get three axis, then the slugs would have same problem as pellets. The very point of this video is the corelation of drag (or flare as some preferred to call it although the momentum derives from drag) and spin stabilization (gyro) stabilization. Both of these two are only present in shapes like pellets at the same time and the problem is that although flare is only dependent of the airflow, the gyro is not, it is actually dependent of derivative of the projectile movement and causes 90° force to the momentum it is caused by. This is best demonstrated by the fact that the spirals are ALWAYS in opposite direction of the pellet rotation. Just think about how weird that is :) You are right that the issues needs a "trigger" and that trigger is imperfection of the projectile (or a ever so slight wooable at barrel exit). That is the initial condition that is required, same as with Dzhanibekov Effect.
@gregorkamensek3923 two axis of inertia? at 9:55 :
czcams.com/video/1VPfZ_XzisU/video.htmlsi=t_Z2NYML8uyNHgv1
@gregorkamensek3923
At 9:55
czcams.com/video/1VPfZ_XzisU/video.htmlsi=OF1cslT15F_PuGV1
But well... indeed, you have the full right to believe in whatever you like! Have a nice day.
Good job!
Great explanation Thanks moor Please
Excellent informative
Thank you…
what range of twist rate is the correct for shooting pellets at long distances and at moderated speeds (no more than 900fps)
I was just thinking during his video that maybe the props you should use would be a Batman Birdy and spinning top
Very well explained, I was able to understand from you not from Matt :)
Gregor hvala za poučen video in znanje, ki ga deliš na posnetku.
Hvala :)
Thank you for this. I love brain food and this really helped me understand this issue much much better. I have a completely different outlook on this matter now and I have no doubt others will also. Very helpful. Oh, by the way, the LCS SK-19 and the Huben have a completely different trigger group altogether. I wish I could send you a picture of mine I have on my phone. Mine gun stopped firing suddenly after 6000+ rounds and was sent back. The action is similar if not the same as the Huben but that’s about it. I don’t know if that’s a good thing or a bad thing because I don’t have a Huben yet, plus 5000 psi is a heck of a lot of pressure and my compressor is only rated for 4500 of which I only fill to 42-4300 on a fill. Being that the Huben is regulated wouldn’t matter with a lower psi fill but still would get less shots at a lower pressure. Anyway, just wanted to let you know they are a little different.
Thanks for the info. Yeah, the trigger has to be different as LCS also has full auto. There is not simple mod that would enable K1 to have it so it makes sense that the trigger cannot be the same design.
Unfortunately this video is based on a completely wrong assumption. Pellets are not drag stabilised, never have been and never will be unless someone ties a parachute or ribbon on the back of their pellet. Pellets are flare stabilised and flares stabilise by producing lateral stabilising aerodynamic moments about the CG, not through drag. If the pellet was travelling at around 6000ft/sec then there may well be a drag stabilising moment but subsonic aerodynamics simply do not work as described in this and other videos purporting to describe pellet stability (the one recommended by Gregor contains more than 20 mistakes at my last count, some of which are major completely misleading mistakes). The centre of pressure on any projectile is associated with lateral forces, drag makes next to no contribution to its position relative to the CG.
As a simple test perhaps the drag stabilisation proponents can explain why projectiles with cylindrical bases are apparently not drag stabilised when the base drag on them is much higher than the drag on the front when it is streamlined, just as it is on a pellet. Alternatively, wadcutter pellets have most of their drag on the front and should therefore according to the drag theory be unstable but they are not, why is that?
All that is being described in this video is the basic gyroscopic reaction to a lateral moment about the CG, nothing to do with drag. Gyroscopic stability relies on this reaction and without it nothing would ever be gyroscopically stable. The reason pellets spiral is through a loss of dynamic stability leading to dynamic instability and an increase in yaw angle rather than a decrease when the pellet is dynamically stable. It is all tied in with the ratio between the pellet spin rate and its forward velocity, it is changes in this which produce dynamic instability.
So why should anyone believe me rather than the video? Maybe because I spent almost 40 years working exclusively on the external ballistics and aerodynamics of gun launched projectiles having been trained in aerodynamics and ballistics.
Hi. I appreciate your input. I have studied it and I understand it and you are correct in using the wrong terminology for the force that is trying to keep the pellet flying straight (flare instead of drag). Interestingly enough, everyone is using the work drag stabilization for pellets; I have only found a few that uses flare stabilization and this was not that I am aware of this term. However this does not much for the base of this video as the force of drag would act in the same direction as flare force does and the result in this case is the same (it is trying to get the pellet orientation facing the pellet head in direction of the flight). As mentioned the beginning of the video, I am not a physicist nor English is my native language, so terminology mistakes are bound to happen. In any case, I will correct this in the next video (the video itself will be about different topic though). Since you seem to be interested in the topic (related to airguns), I would encourage you to make your own videos or at least contribute your knowledge to airgun community. We would desperately need people that understands this, possible better than me :). There are tons of material on the firearm projectiles and supersonic flight but very little to none about subsonic airgun projectiles.
@@gregorkamensek3923
Thanks for the reply. Your English is fine do not worry about it, I am sure it is much better than if I tried to talk in your language. I write on a number of forums under the label Ballisticboy, mainly the GTA forum, the UK Airgunforum and the UK based Shooting the Breeze forum. I have recently put an explanation on pellet stability and the different types of stability on the GTA forum. It attempts to explain that drag plays little to no part in pellet stabilisation and that it is lift forces at right angles to the drag, produced by suction on the side of the flare, which produce correcting moments. The whole reason why flares are used is because they produce a stabilising lift moment as predicted by slender body theory and stability is all about moments about the CG, not forces. The vasy majority of the drag force cannot produce any moment about the CG.
As for making a video, if I did everyone would be asleep after the first couple of minutes. It is a pity as I have a simple device incorporating a freely moving flywheel made for me by the late Gerald Cardew, an airgun pioneer, which demonstrates very simply how gyroscopic stability works.
@@milesm1465 I agree with you an all parts, including the one about most people falling asleep as this was my main concern when going in this video, so you might be surprised by response as I was :). I would love to see the freely moving flywheel, I am sure that it looks way more convincing than my ball-baring spinner. LOL
Gregor, do bullets have higher (faster) twist rates and is that a good thing for bullets? For example, what is the average twist for a .22 rim fire rifle? Also, do large caliber center fire rifles, eg. .308 have the same twist as a .22 rim fire?
Yes, generally barrels for bullets have faster twist rate than barrels for pellets. The required twist rate for bullets depends on many parameters like caliber, bullet length, velocity,... So here are some examples: standard airgun barrel has approx 1:18" twist, standard .22 LR barrel has 1:16" or even faster, typical 308 has 1:12".
Typical rule is: the longer the bullet the faster twist is required, the smaller the caliber again faster twist is required...
Hello, congratulations for the video. I'm going crazy, because my cricket tactical carbine 2 in 5.5mm at 50 meters with JSB of 18.13 group well (880 FPS); but, with 25 grain, it makes that "spiral" and I CANNOT CORRECT IT. From your video I have a better idea of what I should do. What do you recommend, increase or decrease speed? Thank you.
Are you using Monster Redesign? Those should be stable... Standard .22 LW barrels (and also other like CZ) are in my experience very prone to make the pellets spiral. Poly barrels are much better in this regard. But in any case, lower velocity is usually better although you are already quite low I imagine so I am not sure they will solve the problem.
@@gregorkamensek3923 thank you very much for your reply. Tomorrow I will test and take your recommendations into account. thank you

I would be interested in knowing about transfer ports
so what what twist rate is preferred for higher velocities? and what range of fps do you regard as high velocity?
That depends, I assume that you are talking about pellets since this video is about pellets. If I would have to set a threshold for what is high velocity, I guess I would say everything above 950 fps. Here is an example. RTI long range barrel uses 1:32" twist and at the EBR, I was shooting Monster Redesign at about 1040 fps. At these velocities, the probability that the transonic air around the pellet is higher (compared to typical "regular" velocity) but there are definitely no spirals caused by the effect described in the video that would most likely appear with regular twist barrels. All I am trying to emphasize here is what is the reason for pellet spirals and not every pellet will behave the same and there is a definite limit of the pellet shape and sectional density that limit the optimal velocity but in competition where the use of pellets in mandatory (like EBR), one of the very important things is to be able to shoot with as high velocities as the accuracy allows it simply because the shooting takes place in outdoor environment.
Hi Gregor
In my Edgun Matador cal.30 Super long, from time to time I see how the pellet makes this turn ..... same shot 30 times, and the shots are good and the next shot 31 does this ??
I have tested at different speeds 270ms, 275ms, 280ms, 285ms, etc. and it is always the same
You already tell me what you think since you have an equal to mine.
B, regards
nice vido ,bro , i learn more about airgun and pellet now ， thanks for sharing .
how about slug ? it will also spiral as pellet too ? i am interested in slug , it have better BC and is good for long range shhooting
Looking forward to your more videos ）））
Slug can spiral as well but unlike the pellet, spiraling is usually not progressive and direction of spiral is the same as the twist...
@@gregorkamensek3923 So what causes spiral for slug? I watch Matt's video about slug, and I think it may be related to muzzle velocity. 950FPS or highermuzzle velocity will have tighter groups
you say pellets need fast twist rates, but FX after many tests discovered that slower twist rates are better for pellets and faster twist rates are better for slugs,. thats why the FX pellet liners are 1:28 and the slug liners are 1:20
No, actually I said just the opposite, pellets need slow twist. Also if you check my video about the pellet barrel from RTI, it is 1:32" twist.
So in short words pellet at further distances just simply drop and gyroscopic effect is not in line with drag stabilisation.
Better way of saying would be that this 90° difference of cause an effect between those two stabilization causes an oscillation because a positive feedback loop is presented and any minor starting deviation from perfect axis alignment of pellet and flight path is amplified with time (or length of flight) due to those positive feedback loop.
Thank you Gregor, I've been waiting for this kind of series from someone that can explain it without the math ( maybe a little ).
I have a question; is it possible to tune a pcp to a particular pellet for accuracy, ie after sorting for size and weight, If I have a lot of one type of pellet.
Don't want to waste them.
Again thank you.
If the pellet size is appropriate for the barrel and the pellet design is good (meaning that the pellet is capable of accurate flight), then probably yes. But the problem is that if the reason for lack of accuracy is too high spin (twist), you will simply need to shot it at lower velocity or get a barrel with slower twist rate.
@@gregorkamensek3923 Thanks for reply.
What twist rate and speed would you suggest for 10.33 Gn .177 Diablo out to 50m for best accuracy.
I realise theres more to it than twist rate and speed, but as a starting point.
Regards Peter
@@petera7070 Standard twist (1/18") should do just fine for .177 and 50 meters.
The only way to find the best air pressure, hammer spring adjustment and muzzle velocity combination for the best accuracy is to test...a lot. Start at a low air pressure (if regulated) and hammer hit and slowly increase the pressure and when that stops the fps increase add more hammer spring until fps stops increasing, then add more air pressure etc, etc, etc. Shoot 5 shot groups at each setting and you will see them hit all over except at one combination - that's the one. Be prepared to shoot a lot of pellets.
Weighing and head sizing helps. Eliminate the light and heavy ones. Then find which head size works best in your gun and test with these.
What would be a good long range barrel twist rates for pellets? 1: 18 or 1: 20
It depends on pellets weigh and length
Nope. It depends on the speed.
@@james1795 I have a benjamin maximis .177 the rifle shot the jsb 13gr pellets will at 830 fps. Tomorrow I will be testing different pellets slugs and different velocities. I also have a hatsan nova. 177 and it doesn't shot any pellets will only the 21gr nsa slugs @ 880 fps. I believe the benjamin maximis has a 1:26 twist rate. The twist rate is slow for slugs but it may be good for pellets.
@@airgunsofidaho4886 I don't have a Maximis. But testing some of my .177s I get the best groups with H&N Baracuda Match also sometimes even better groups with the Beeman Kodiak Match. Both are 10.65gr and made by H&N only in different dies. Keep in mind these .177s are made in different diameters to choose from which can make or break the "perfect" group we like to see.
@@airgunsofidaho4886 Just to add. If you are getting 830fps out of the 13gn, a 10.65gn will be coming out hot, maybe not too hot to lose stability, but something to keep in mind.
Hello Mr. Gregor I am very interested in the longer barrel for the Huben K1 gen 5. Did you ever succeed in this design?
You mean longer thane 600 mm?. I have actually used about 660 mm in my first videos with K1 and I also had an idea to modify one K1 with about 750 mm barrel but I don't know if I will actually do it...
Pozdravljen, imam vprašanje za tebe. Lahko kako zasebno komunicirama?
Emial, tel, Whatsapp... Samo ne morem ti posredovati informacij na javni platformi...
@@gregorkamensek3923 Moj mail je lukasipek@gmail.com.
Imam vprašanje za PCP polavtomatsko puško.
Ok I'm at 3:19 and i swear i haven't seen your video before. I'm going to guess that why you say pellets spiral is something similar to why at low speeds of a centrifuge one can get away with inaccuracies of the tubes not being weighed out correctly but as soon as one increases the speed, say to getting up around several g; several things will happen (maybe even quickly LOL One is the centrifuge will begin to vibrate like hell, it may even move off the bench if it is indeed a bench mounted one then you'll be blown up by your boss if your not the boss of the lab and finally if not stopped by an automatic cut out you could have a serious accident depending upon the speed. So I'm thinking that since in reality airgun pellets are not exactly symmetrical or at least they can be easily made non symmetrical by clumsy fingers or just come that way and hence the rotational axis can easily be off centre. Ok there O've said it LOL. I'm not a ballistics guy nor an engineer but some crazy scientist LOL. Now I watch more!
Yes, that is let's say the initial reason for issues that everyone thinks off but as you have probably seen from the video, I wanted emphasize to the relation and cause / effect of a dual stabilization any why this problem progresses... Also, based on this theory the RTI long range barrel for pellets was developed that has amazing results with pellets as close to sonic speed.
Yeah after I watched your video i checked out their site. Amazing looking for sure. Would love to have one but maybe it could be divorce if i did LOL Thanks for the feed back!@@gregorkamensek3923
👍
Just a minor correction. You mention in your excellent video that a bullet stabilizes due to “angular precession.” I do not believe this 100% correct.
Consider this small summary of physics 1.0.1. below:
In physics, angular momentum is the rotational equivalent of linear momentum. Like linear momentum, angular momentum is preserved. In practice that means angular momentum of a linear moving particle (f.i. a bullet) has a “pseudovector” (read direction) which is also conserved; i.e. remains constant. This is why a pellet or bullet spinning around its longitudinal axis keeps pointing in the same direction.
Precession is a change in the orientation of the “pseudovector” of a rotating body (but not “nutation”). Precession can be caused by external forces AND/OR without any external forces (torque free precession). This effectively means, all spinning particles (bullets) are subject to precession, “wobbling” (but not “nutation”).
The most important thing here is that in practice (and theory) the conservation of angular momentum causes bullets to fly straight. Not angular precession.
P.s. “Nutation” is, more or less, non-contant precession.
Thanks for the input. I really appreciate this kind of comments!
Hm, I have to be honest, I checked the word "nutation" before I began forming the answer despite the fact that I know the word but I wanted to make sure I know the correct meaning. You are right that nutaion can be the cause for bullet wobbling but tis (from my understanding) is purely based on the fact that the center of mass in not it the longitudinal axis of the bullet or if the bullets shape is not symmetric and the air friction (drag causes) this wobble. But you are right that if you think about it, the bullet just creates an axis of the angular momentum that is unlike in the with the pellet not changing direction. I should have put this in the video :). That is why I like this kind of videos as I get a chance to learn more :). Thanks!
Gregor Kamenšek : I am glad I was able to assist! For the avoidance of doubt, your explanation why pellets “spiral” and other explanations are fully correct. I just thought it would be useful if the correct terminology is used; Conservation of Angular Momentum: The cause why spinning projectiles fly straight (in vacuum), Precession: The “wobbling” of projectiles with a 90 degree phase shift caused by “fluid-dynamical” disturbances (a change in the “first Euler angle”) and Nutation (Latin for “Nodding”): Variations in Precession, caused by a change in the “second Euler angle.” As I stated above, I believe you are correct in that Precession causes the spiraling of pellets. But due to the fact that projectiles move in 3 dimensions, rotate around 3 axis, have imperfections in their internal consistency AND the influence of “fluid-dynamics” makes mathematical modeling of the flight of pellets extremely difficult. Perhaps a nice subject for a PhD dissertation, but hardly interesting CZcams material...;-)
Looking forward to your next CZcams video!!!
@@paulerhard1252 Thank you for your corrections. I fully understand them and agree with them. Thank you also for explaining correct terminology :)
oh yes greg so ur also up into 3d heli hobbie... i think u also know how to invert fly tricks haha.
anyway regarding the heli blades the term use to call when blade shifting down and up is called pitch. pitch propeller . negative pitch and positive pitch. that was driven by swashplates.
Yeah, I used to be... But I don't practice anymore and I would not dare to invert the heli anymore. In my "best" days I quite confidently inverted it but I definitely did not know to do any 3D tricks... Yes, correct it is called pitch and these helis are called collective pitch because the blades RPM is constant (Governor mode) and only the pitch determines lift and controls...
@@gregorkamensek3923 haha and its very expencive hobbies ... the more u having fun about the tricks the u spent thousand of money and i stop this hobbies by looking for some another hobbies that is not so expencive hehe. better go into drone hobbies and aerial video much better ...its not that expencive and very entertaining.
@@gregorkamensek3923 hellow greg hows it going...? i bet u know the lcs sk19 semi full auto? how u compare that pcp to huben k1? which one is best for longrange?
and also how u compare the fx impact to huben when it come to longrange. knowing that the impact has the lower power in footpound energy... but ive seen some utube vlog that the impact mk2 reach the 415yard shoot. but that is maybe bigger caliber