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Improving darts - some thoughts

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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Unread postAuthor: jonot05 » Thu Oct 02, 2008 2:58 pm

Does your cannon have much recoil? If it does then you might have difficulty mounting a scope so that it does move.
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Unread postAuthor: Ragnarok » Thu Oct 02, 2008 3:05 pm

jonot05 wrote:Does your cannon have much recoil?

Don't know yet, I'm still building it. :P

However, I do know how to fit a scope so that it won't move - I've argued with my springer before, and those are notorious for scopes wandering along the rails.
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Unread postAuthor: john bunsenburner » Fri Oct 24, 2008 5:35 am

why use darts and not self made bullets they are alot smaller not as much air resistance, they are simple to make and each one of them can look the same. then all you need in a strong gun and its easy!
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Unread postAuthor: Ragnarok » Fri Oct 24, 2008 6:20 am

john bunsenburner wrote:why use darts and not self made bullets they are alot smaller

Because darts have numerous advantages over bullets.
Drag forces are based on the frontal areas of a projectile. Smaller overall is one thing, but smaller cross sectional areas are another, and that's what you need.

Not only is it easy for them to be made subcalibre, unlike most bullets - which reduces the drag forces, finned darts can have very long bodies, which is good for air resistance and target penetration, because they have more mass for the same drag.

The design I'm working on also doesn't need a rifled barrel unlike a bullet would, and that's the clincher, because making rifled barrels is exceptionally difficult without tooling which I don't have.

For this kind of application, darts are vastly superior to bullet shapes. They might not have the "K.O." factor of bullets, and they're harder to make, but for long range and penetrative capability, they can't be beaten - why do you think the army uses them for anti-tank rounds?
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Unread postAuthor: jackssmirkingrevenge » Fri Oct 24, 2008 7:51 am

john bunsenburner wrote:then all you need in a strong gun and its easy!


That's the beauty of saboted darts, they maximise the power you already have by optimising the parameters - namely velocity and sectional density - which give the best penetrative performance.

It's a bit like having a heavy car. Why add a bigger engine when you can keep the one you have and use a lighter chassis. Even better, you can then add a bigger engine and have even more performance ;)
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Unread postAuthor: ALIHISGREAT » Fri Oct 24, 2008 7:59 am

since this topic is bumped... what kind of drag coefficient are you aiming for?
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Unread postAuthor: Ragnarok » Fri Oct 24, 2008 8:11 am

ALIHISGREAT wrote:since this topic is bumped... what kind of drag coefficient are you aiming for?

Below 0.1 ideally, which I think I can do. I'll need to get actual figures for it when I've made them though.

@JSR: It sounds like the development of the Ariel Atom 500!

Take Toyota engine (I think, anyway) - put it in scaffolding that weighs less than half a ton instead, and get something that will do 0-60mph in under 3 seconds.
Then get bored and build a supercharged 500hp Aluminium V8 for your scaffolding instead, and while you're at it, add a load of downforce as well.
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