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Airsoft Damage Challenge

A place to ask general spud cannon related questions.
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 30, 2009 8:45 am

Ragnarok wrote:*Which sounds like it's trying to be a name for some product that the marketing department wants to try and sell to men who think they're butch and manly. "Buy Mach One-Two-Five, now with 400% more testosterone!"


When really, the proper manly thing to do is shave once a month, with a bowie knife and old bathwater :D

Back on topic, momentum is good, but velocity is also important. The projectile must be going fast enough to penetrate the target medium without giving it time to deform and absorb the blow. There's a good discussion on penetration here.
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Unread postAuthor: Ragnarok » Mon Nov 30, 2009 9:55 am

jackssmirkingrevenge wrote:The projectile must be going fast enough to penetrate the target medium without giving it time to deform and absorb the blow.

This is an important point, and it's why my AP dart designs are deliberately being pushed to about 270 m/s (about as fast as moderately practical for a pneumatic), in order to try and minimise the target's absorption of a hit.
Similarly, more velocity reduces the deformation of the projectile - which is why a 90 m/s paintball can be flattened against sturdy card, but a 300 m/s one can go through intact.

However, in this case, due to relative projectile and target hardnesses, we can probably say that the issue is not so much projectile deformation as the projectile being annihilated. The energy is not going effectively into the target, it's going into the BB.

As something of an imaginative aid, consider a semi-elastic collision between two masses.
Looking at it as such, a projectile really wants to be more massive than however much it's got to punch through, else it's suffering a large change in kinetic energy, a lot of which will go into its own deformation.

In other words, the sectional density of the projectile should be higher than that of the target. You can get away with less SD if you add enough velocity, or with more SD, less velocity.
But you shouldn't rule out either. Both sectional density and velocity are needed, and there'll be a sweet spot of projectile mass where both velocity and SD are high enough. Too fast, and there won't be the SD to be efficient. Too heavy, and there won't be the velocity to be efficient.

How fast is velocity enough, and how massive is SD enough will vary with each target of course. Cheese isn't too fussy either way. Steel plate is quite picky about what will make it through, particularly as thickness increases.

I got quite fanatical about the subject of efficient penetrators in the early stages of designing the AP darts, so I do have a few ideas on the matter.

Anyway, as DYI's BBs are likely already doing 1300 m/s or so, it's unlikely that practical increases to their velocity will be improvement enough.
With a heavier, slower projectile, the increase in SD might give it the edge.

I do have amongst my arsenal of ideas something that would get a 0.3g BB up well into hypersonic velocities (if I ever built it), but that's another whole ballpark.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: kenbo0422 » Mon Nov 30, 2009 10:28 am

And before we fall into the old trap: Inertia and momentum, although used in common speech to mean the same thing, are separate concepts.
Numerically, inertia is simply an object's mass. Momentum is the product of an object's mass and velocity.


Exactly your point. A higher mass bb has to be used.... steel or lead comes to mind :D
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Unread postAuthor: Ragnarok » Mon Nov 30, 2009 1:29 pm

kenbo0422 wrote:A higher mass bb has to be used.... steel or lead comes to mind

Then falling outside the criteria set. 6mm plastic only. If you start using metal ones, then hardness comes into the equation, messing things up.

It's not hard to find a more massive plastic BB than 0.12g though.
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Unread postAuthor: kenbo0422 » Mon Nov 30, 2009 1:39 pm

What about leaded plastic?? Anything to increase the mass weight and still keep it as a plastic BB.
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Unread postAuthor: Ragnarok » Mon Nov 30, 2009 2:14 pm

Leaded plastic still changes things. We can be pretty sure the plastic will disintegrate, and then the lead is exposed.

Still, 0.43g plastic BBs are possible, and that's still a respectable way closer towards a 1.28g lead BB.
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Unread postAuthor: ohspyro89 » Mon Dec 07, 2009 2:29 pm

That's odd that the BB is still in tact. Most bbs I've used shatter quite easily. The rifle I use to skirmish, will break bbs when they hit a soft sticky rubber target. I use .3 gram bbs though, so it may have something to do with it.
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Unread postAuthor: Larda » Mon Dec 07, 2009 4:25 pm

The BB in the picture is just for comparison.

DYI wrote:I can say that there is 1" of wood between me and the launcher, and that, at these speeds, bouncing is not an issue - the round either punches through, and shatters into tiny pieces, or fails to punch through, and shatters into tiny pieces.
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Unread postAuthor: Davidvaini » Mon Dec 07, 2009 10:06 pm

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Unread postAuthor: DYI » Mon Apr 19, 2010 8:24 pm

I'd just like to remind everyone that there is an open challenge here, which is quite simple; launch an airsoft round at a dime, Canadian or American with whatever you've got laying around, and send in a picture of the result. I didn't seriously expect any of you to put one through a dime, but it would be interesting to see some other attempts for comparison.
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Unread postAuthor: SpudBlaster15 » Mon Apr 19, 2010 10:00 pm

Trying to motivate my friend SWIM are we? :lol:

I may have some interesting pictures within the next few days (I know you've heard that one before :roll: ).
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Unread postAuthor: JDP12 » Wed Apr 21, 2010 12:05 pm

Hmm... I may have to consider attempting this now..

Just to see what would happen.
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 21, 2010 12:41 pm

Any excuse for some high speed video, here's 0.25 and 0.15 gram airsoft BBs respectively out of one of my 6mm mini-pistons at 500 psi, fired at a 5 euro cent coin:

[youtube]http://www.youtube.com/watch?v=Ewmbt8zzqYc[/youtube]


[youtube]http://www.youtube.com/watch?v=5Y4pT6MVWWk[/youtube]

Path of least resistance, the BBs just shattered into smithereens (you can see the shrapnel puncturing the cardboard backing above the coin in the first one), marked the surface of the coin but no visible distortion if viewed from the side.
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Unread postAuthor: woodscout » Wed Apr 21, 2010 1:24 pm

i just had an idea.. mayby i just put the coin to my forge and warm it "a little" :twisted: and shoot it throu with my modified AEG airsoftgun :D
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 21, 2010 1:42 pm

Beware splashes of molten metal :roll:
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