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High pressure gun --> silencer video update

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: POLAND_SPUD » Mon May 11, 2009 5:01 pm

well I don't think that ammo is the problem here... it seems pretty well made... what did you use to make it ?

my guess is that you jerk the gun when you pull the trigger.. I think I could see that on the vid but I it's hard to tell when muzzle velocity is unknown and the gun is not visible at the same time...

what is more I suspect that the mass of the gun and lack of ergonomics make it pretty difficult to shoot it in unsupported position

ohh and don't use a laser sight.. it looks cool but it really sucks for real aiming
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Unread postAuthor: jackssmirkingrevenge » Mon May 11, 2009 5:04 pm

POLAND_SPUD wrote:well I don't think that ammo is the problem here... it seems pretty well made...


I disagree, the tail is the only support meaning there is no control over which direction the nose is pointing when it leaves the barrel, I don't expect to see a tight grouping with this even with the launcher clamped still and consistent valve opening time and chamber pressure.
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Unread postAuthor: POLAND_SPUD » Mon May 11, 2009 5:19 pm

uhmmm I didn't think of that... but still his ammo looks very well made

would a sabot cause accuracy problems?
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Unread postAuthor: jackssmirkingrevenge » Tue May 12, 2009 12:15 am

POLAND_SPUD wrote:would a sabot cause accuracy problems?


Saboted rounds will always be less accurate than their full bore equivalents, this is partly why projects like the Special Purpose Individual Weapon or the Steyr AMR have not met with much success, and why for example the British were so reluctant to give up their rifled tank cannons for the smoothbore guns that have now become the world standard.

Saboted ammunition must be very finely manufactured, and carefully designed in such a manner that sabot separation is consistent and doesn't tip the projectile. This can be done of course, we have tanks today that with APFSDS have scored kills over 3km away, but it needs the sort of dedication and resources only the military usually have.
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Unread postAuthor: Moonbogg » Tue May 12, 2009 6:02 am

I bet a good one could be made out of balsa wood. A cone shaped indentation could be drilled at the tip to cause rapid seperation of the halves.
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Unread postAuthor: jackssmirkingrevenge » Tue May 12, 2009 6:08 am

It would still be a pain to make them consistent unless you had a lathe.
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Unread postAuthor: Technician1002 » Tue May 12, 2009 6:33 am

jackssmirkingrevenge wrote:It would still be a pain to make them consistent unless you had a lathe.


For a heavy nail such as a cement nail, it would be easy to make one with a wood dowel. Drill the dowel to fit the shaft of the nail. Cut the dowel lengthwise. Cut a curf on each half 1/2 inch from one end. Lay the nail in the groove made by the first drilling with the head of the nail resting in the saw curf.

Assemble the other half on top. Load and shoot. The original drilled hole will provide the opening to separate the halfs upon launch leaving the nail to free flight.
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Unread postAuthor: Hotwired » Tue May 12, 2009 7:42 am

jackssmirkingrevenge wrote:and why for example the British were so reluctant to give up their rifled tank cannons for the smoothbore guns that have now become the world standard.


Also HESH rounds need spin to work properly, cost less than penetrator rounds and are a hell of a lot more likely to be used.

On the other hand penetrator rounds hate spin, British sabot rounds need to have special bearings to cancel out the spin of the rifling.

Cheaper demolition projectiles or cheaper anti-tank projectiles. Where's the tanks eh?
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Unread postAuthor: jackssmirkingrevenge » Tue May 12, 2009 8:05 am

Hotwired wrote:Also HESH rounds need spin to work properly, cost less than penetrator rounds and are a hell of a lot more likely to be use.


Not strictly true, yes they need to spin because rifling increases accuracy and it needs to hit its target to work, but spin doesn't affect the function of the round in terms of target damage. Rifling also has a negative effect on HEAT rounds as the spin tends to disperse the gas jet due to centrifugal force.

Besides, HESH isn't really useful against a modern battle tank because of composite armour and internal liners that have become almost universal and defeat the "spall" effect HESH needs to work. It still shines as a demolition charge though, beloved by combat engineers ;)
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Unread postAuthor: Hotwired » Tue May 12, 2009 8:18 am

Accuracy is a useful part of the whole works ^^

Rifling is less practical though by no means obsolete for tank cannons when used against other tanks.

Chances of meeting modern MBTs = bugger all

Chances of wanting to flatten a concrete wall without the mess of HE = by comparison, very high

So the logical thing is to go for improving the penetrator and HEAT rounds.

Such is army logic. There are much worse things that they've got round to doing though.
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Unread postAuthor: MRR » Tue May 12, 2009 10:57 am

@ Poland_Spud
This is what the darts are made of...
Image
And you are right, the gun is not very ergonomic and it is hard to aim with it.

@jsr
Do you think something like that would make the dart more stable during flight?
Image
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Unread postAuthor: thedeathofall » Tue May 12, 2009 11:50 am

Those tails look interesting. What are they?


As to flight stability, there are several options. you can always make fins for the darts, but that will be costly, and time consuming. Another options is to just leave them the way they are. They wont be pinpoint accurate, but cheaper than anything else.
Of course, if you take something like a piece of dowel and drill a hole through the center and place it on the dart, so that the dart is held centered in the barrel, it will probably increase accuracy.
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Unread postAuthor: MRR » Tue May 12, 2009 12:04 pm

Those are special screw anchors for ?pore concrete? .
I could imagine that they make the projectile spin during flight and provide a certain amount of stability.
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Unread postAuthor: POLAND_SPUD » Tue May 12, 2009 12:07 pm

@thedeadhofall I think it's made from nozzles for silicone sealant guns

EDIT
ohh you meant the one in the other pic
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Unread postAuthor: thedeathofall » Tue May 12, 2009 12:18 pm

Actually i was talking about the ones already in use :wink:

so sealant gun eh? that would be kind of expensive unless you use a lot of them all the time. Do you get them form work?

The screw anchors should work really well as long as they fit the barrel. they should provide a rifling affect or something similar to an arrow.
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