If you could shoot a lead Diabolo pellet at 1400FPS, what would be the factors that would cause it to destabilize?

Jump to latest Follow Reply
SkeeterHawk

SkeeterHawk

Member
Oct 23, 2021
684
621
Florissant, Colorado, United States
This should (hopefully) be a fun question for the group:
If you could shoot a lead Diabolo pellet at 1400FPS, what would be the factors that would cause it to destabilize?​
  • Would the blast of air required to get it to that velocity deform the skirt against the barrel?
  • Would the "dirty air" coming out behind the pellet flip it over?
  • Would the rifeling be too fast regardless such that the pellet wouldn't spin, but just get torn up on the way down the barrel?
    • Would a smooth-twist barrel fix that issue?
    • Badger5th suspects that the head of the pellet may get blown off and leave the skirt in the breech
  • Would the increased barrel-whip be the nail-in-the-coffin?
  • The BC would be jacked up and cause the pellet to get into trans-sonic soon after firing (Scotchmo's contribution and "hurrumphed" by others)
  • Increased Gyroscopic Effect if the pellet engages the rifeling (Dizzums contribution)
  • What am I missing?
 
Last edited:
  • Haha
Reactions: SoulSniper
one of the main factors at play with pellets is theyre designed to fly and stabilize by air flow .. supersonic forces affect them negatively, at least around the mach point .. also there exists some opposing forces from the twisting motion caused by rifling which imparts a gyroscopic affect and tends to keep the pellet in a single plane inline with the barrel .. it tends not to follow the flight arc and can get tilted in relation to the airflow .. examples of this show up on paper sometimes as a 'side profile of a pellet' hole ...
 
  • Like
Reactions: beerthief
Upvote 0
beerthief said:
would 1400 FPS increase lead loss due to friction/speed in the barrel ? possible damaging the edge of the skirt in an erratic manor ?
Click to expand...
That was my thought with my third point, that it would just scoot past the rifeling instead of engaging.

Scotchmo said:
It might fly fine out to 15yd, at which point it transitions to subsonic and bad things happen to the air flow and shock wave. There is a big disconnect between subsonic and supersonic. Best to keep it one or the other, not both.
Click to expand...
You're probably right. There is enough drag that it would have the worst BC ever at those velocities.

dizzums said:
one of the main factors at play with pellets is theyre designed to fly and stabilize by air flow .. supersonic forces affect them negatively, at least around the mach point
Click to expand...
Yea, that was why I was pushing them out well into the super-sonic range before they exit the barrel. As Scotchmo pointed out, they will probably hit trans-sonic in the first 15 yards.

dizzums said:
also there exists some opposing forces from the twisting motion caused by rifling which imparts a gyroscopic affect and tends to keep the pellet in a single plane inline with the barrel .. it tends not to follow the flight arc and can get tilted in relation to the airflow .. examples of this show up on paper sometimes as a 'side profile of a pellet' hole ...
Click to expand...
This is an interesting point. So if the pellet could engage the rifeling and not get torn up, it would be spinning really fast when it exits, so the gyroscopic effect would come more into play.
 
Upvote 0
Diabolo pellets rely on the skirt to stabilize their flight via drag forces, but breaking the sound barrier creates a sonic shockwave that travels over the body and then the skirt of the pellet changing the drag dynamics. Unlike with bullets there is much less spin to stabilize the pellet as the center of gravity/pressure changes due to the sonic wave creating more pitching and yawing, maybe even tumbling. I’m only guessing but the pellet doesn’t have a strong enough axis of rigidity to counteract the turbulence due to the slower twist rate of the pellet.

-Marty
 
Upvote 0
SkeeterHawk said:
This should (hopefully) be a fun question for the group:
If you could shoot a lead Diabolo pellet at 1400FPS, what would be the factors that would cause it to destabilize?​
  • Would the blast of air required to get it to that velocity deform the skirt against the barrel?
  • Would the "dirty air" coming out behind the pellet flip it over?
  • Would the rifeling be too fast regardless such that the pellet wouldn't spin, but just get torn up on the way down the barrel?
    • Would a smooth-twist barrel fix that issue?
  • Would the increased barrel-whip be the nail-in-the-coffin?
  • Increased Gyroscopic Effect if the pellet engages the rifeling (Dizzums contribution)
  • What am I missing?
Click to expand...
the drag will bring it into transonic fluid around it, very soon, say within 100m, if it makes out its way of the barrel straight... Throughout it's path it won't be a repeatable experience You would want to rely upon for hunting/shooting... Besides, Mach1 1125+ fps You'd also make that supersonic crack that's too loud to wary away the pests...
 
Upvote 0
With pellets at those velocities I would expect issues with skirt flare from excessive RPM's and possibly tearing the skirt off in the breach with only the head exiting the muzzle. Based on soft lead being standard for airguns I would also expect severe leading at those velocities. A slug cast from 50/50 wheel weights/linotype would at least have less of a leading issue and even then even 4,500 PSI may not be enough to properly obturate alloy that hard.
 
  • Like
Reactions: SkeeterHawk
Upvote 0
Gerry52 said:
Original Smooth Twist barrels wouldn't solve the 1400fps thing
Click to expand...
Thank you for addressing this question, Gerry52, as I have yet to own an FX, so I am depending on your input for this based on my limited knowledge of the platform (yet).

Gerry52 said:
High speed is counterproductive to skirt stabilized projectiles
Click to expand...
This is what I'd hoped would make this topic "fun". We know if you look at the Gamo Swarm box, it is saying 1300+FPS. Since this is using non-lead pellets, we can discount some of the nuances that we are discussing here, like the fact that lead is so soft and that it would probably "explode" in some way out of the gun...in the breech (@badger5th), or on the way out of the barrel (like @beerthief validated). I believe pretty firmly that the velocity would make the pellet sail past the rifeling without properly engaging, so it would tear the skirt to heck on the way out of the barrel. A 1:24 or something longer may work, but this would require experimentation, for sure. I don't suspect that traditional land-and-groove rifeling would do anything but tear up the pellet, so you would need something more subtle like the smooth twist at a slower rate. Thoughts?
 
  • Like
Reactions: SoulSniper
Upvote 0
hi again, @SkeeterHawk ! saw You're looking forward to the FX products...
for the velocities, You can achieve that 1400fps for pellets in the Smooth Twixt X that comes stock with them now across the platform, but again it won't help with accuracy and the noise it produces. Besides, the Platform is to a good extent service demanding that You'll need to upkeep with...
My first impressions were like i'd prefer my springer any day over the Maverick i also own, but now that i've got a hand over service/maintenance side of it, Maverick is my go-to machine, as i've customized the power wheel to suite the velocity needs and pellets selection...
 
Upvote 0
1662586935265.png
Humidity might be a greater factor of affect at speed. I am just guessing and then temperature vs dew point with said speed. But this would only be revealed at longer distance. Post video if you find out anything interesting please.
 
  • Like
Reactions: MEC17670
Upvote 0
Blankshot17 said:
View attachment 288269Humidity might be a greater factor of affect at speed. I am just guessing and then temperature vs dew point with said speed. But this would only be revealed at longer distance. Post video if you find out anything interesting please.
Click to expand...
I always loved that photo. The vapor is condensed out of the air because of the rapid compression and expansion of air in a standing shock wave. The air is compressed putting tremendous potential energy into it and when it drops sub-sonic it goes BOOM and the water vapor dumps out visibly. High humidity does not increase drag. The water vapor interestingly makes humid air less dense than dry air. That's why it takes a plane longer to take off in high humidity, same as if it were at a higher altitude.
 
  • Like
Reactions: SkeeterHawk and Blankshot17
Upvote 0
SkeeterHawk said:
Thank you for addressing this question, Gerry52, as I have yet to own an FX, so I am depending on your input for this based on my limited knowledge of the platform (yet).


This is what I'd hoped would make this topic "fun". We know if you look at the Gamo Swarm box, it is saying 1300+FPS.
Click to expand...
LOL...marketing hype for the unknowing and unwary. Impress you with how fast the gun shoots so you think oh wow, more power. Never see anything about the accuracy of that super lightweight pellet at those kind of speeds on the box now, do you? Course not because if you did, you'd never buy the rifle.
Of course, then you go looking for reasons why your new gun shoots lousy, you find places like AGN and you find out why :)
Accuracy trumps power. You can have all the power you want but if it ain't accurate, that power is useless ;)
 
  • Like
Reactions: Smitty911
Upvote 0
SteveP-52 said:
Accuracy trumps power. You can have all the power you want but if it ain't accurate, that power is useless ;)
Click to expand...
I absolutely agree, with everything you said, but especially with the statement above.

Yea, that hype is "subtly" the point of this post. We know that the Bold print on the box, in the box stores, is bogus. They don't care if the projectile was a grain of sand, as long as the chronograph said a higher number than the other box on the shelf, it's all good. Who cares where it lands? So that was my thought, the alloy pellets won't blow apart like the soft lead will when subjected to the same conditions. We know that the pellet won't have any accuracy whatsoever when trying to push it to 1400FPS...but what is the reason?...in theory.

All of this said, this question/post was spawned by this post on projectile drag in trans-sonic. This is more relative to a slug, which doesn't have the skirt...and can probably be shot at 1400FPS without getting as torn up on the way out of the barrel. Since we all know that the skirt would be the problem, my favorite thing to happen was from @badger5th when theorizing that the head would completely separate from the skirt, and the skirt would be left in the breech. That's awesome!:p

If the hype was real, bad things would happen. What else could go wrong to add to the list? Could we diesel the lube on the outside of the pellet and cause the pellet to "liquify" down the barrel????:ROFLMAO:
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu