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machined APFSDS projectiles

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Re: machined APFSDS projectiles

Unread postAuthor: Labtecpower » Wed Nov 06, 2013 5:14 pm

In theory faster spin rates should give better stability.
If you have a bicycle wheel lying around, give it a gentle spin, keep it in both hands and try to twist it. This will be pretty easy. Now give it a hard spin, and try to twist it. This will be much harder.
Spin stabilizing also gets less effective as projectile length increases.
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Re: machined APFSDS projectiles

Unread postAuthor: Gun Freak » Wed Nov 06, 2013 5:15 pm

Awesome results!!! Congrats. Their high speed footage is amazing... Especially the one with the socket head screw.
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Re: machined APFSDS projectiles

Unread postAuthor: jackssmirkingrevenge » Wed Nov 06, 2013 9:00 pm

Labtecpower wrote:HAHAA f*ck yes :D
That was exactly the result I was hoping for hehe


You should have seen the grin on my face when I first saw that hit :D

Especially the one with the socket head screw.


Not sure what the hell happened there :) could have been the hollow nose, or the fact that the stabilizing band I machined was causing a shock wave that prevented effective drag stabilisation.
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Re: machined APFSDS projectiles

Unread postAuthor: Labtecpower » Thu Nov 07, 2013 1:00 pm

You should have seen the grin on my face when I first saw that hit :D


I think it was about the same as mine :D

I've fired projectiles similar to the one that spiraled through the air, with the same effect.
I used a golf ball taped to a cardboard tube, it flew about 500 meters, but it did so with a corkscrew effect :roll:

The projectile that got stuck in the plate was made with one of these cores:

Image

I fired some from my hybrid, with the following result:

Image

The point on the last projectile is flattened because I tried to get it out with a sledgehammer hehe

Image
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Re: machined APFSDS projectiles

Unread postAuthor: Talk » Thu Nov 07, 2013 1:28 pm

the round used in shot 5 flew like a radar guided missile :D
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Re: machined APFSDS projectiles

Unread postAuthor: dart guy » Thu Nov 07, 2013 3:46 pm

jsr, you could try filling the socket with lead next time, it my help it, all bullets/ slugs do that spiral but some are less noticeable.
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Re: machined APFSDS projectiles

Unread postAuthor: Labtecpower » Thu Nov 07, 2013 3:56 pm

dart guy wrote:jsr, you could try filling the socket with lead next time


Why would you want to do that?
The idea of those darts is to have the CG in the front.
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Re: machined APFSDS projectiles

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Re: machined APFSDS projectiles

Unread postAuthor: dart guy » Thu Nov 07, 2013 3:58 pm

That would help because the socket is in the front.
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Re: machined APFSDS projectiles

Unread postAuthor: Labtecpower » Thu Nov 07, 2013 4:08 pm

dart guy wrote:That would help because the socket is in the front.


My bad :D
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Re: machined APFSDS projectiles

Unread postAuthor: POLAND_SPUD » Thu Nov 07, 2013 9:51 pm

Why not make them exactly like darts used on blowguns??
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Re: machined APFSDS projectiles

Unread postAuthor: jackssmirkingrevenge » Fri Nov 08, 2013 10:06 am

POLAND_SPUD wrote:Why not make them exactly like darts used on blowguns??


Subcalibre means lower frontal area means lower drag means more velocity retained downrange.
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Re: machined APFSDS projectiles

Unread postAuthor: mako » Fri Nov 08, 2013 11:31 am

JSR, JSR, JSR!!
Having noticed that all your darts that look like they should fly perfectly are not doing so, took a closer look. They look like rockets, not bullets, so aerodynamics says they should fly nicely. But the one that pierced the steel plate had heavier METAL fins on the back.

That got me thinking. Are you taking into account the fact that lighter materiel accelerates more easily? On an arrow the light materiel slows the rear, making it stay straight. But an arrow ceases to accelerate after leaving the string. A gun still has expanding gas leaving the barrel when the bullet exits the muzzle.

This expanding gas could be accelerating your projectiles a little bit; if the acceleration is minor, then the heavy tip isn't moving much, but the light fins are easier to move, causing tumble. The heavier fins seemed to be more accurate, which seems to bear out my theory. The last bit of propellant is still trying to accelerate the round, but the fins are now harder to affect than the tip.

@Labtecpower. Instead of hammering on them, you could try putting them in the freezer or cold water. The shrinkage might be enough to remove them. It might also make them brittle, so watch out.
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Re: machined APFSDS projectiles

Unread postAuthor: POLAND_SPUD » Fri Nov 08, 2013 12:03 pm

yeah, but testing is limited to 10 meters anyway
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Re: machined APFSDS projectiles

Unread postAuthor: mako » Fri Nov 08, 2013 12:18 pm

@POLAND_SPUD. What has that got to do with it? As a matter of fact, the closer the target, the less time the fins have to correct the tumble. I'm saying that the last expansion of gas sort of pops the fins, causing a severe tumble.
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Re: machined APFSDS projectiles

Unread postAuthor: Talk » Fri Nov 08, 2013 12:45 pm

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