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making your projectile go further

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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making your projectile go further

Unread postAuthor: ROCK SOLID » Wed Mar 05, 2008 6:14 am

Well i am new to this forum and to spud guns and i've only built one but i am

going to build more but my neighbor also has a spud gun and he said he can send a tennis ball over a mile :shock: and i asked how he did this

and he said that riffled the barrel making it more stable

I was suggesting that steamlining a object would make it more aerodynamic so it could move faster through the air and go further and using my neighbor idea would send it even further.

PLZ MIND MY SPELLING IS NOT GOOD
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Last edited by ROCK SOLID on Thu Mar 06, 2008 3:25 am, edited 1 time in total.

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Unread postAuthor: Carlman » Wed Mar 05, 2008 6:19 am

i highly dought that his way would do anything at all for starters

a more streamlined projectile would improve distance greatly
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Re: making your progectile go further

Unread postAuthor: jackssmirkingrevenge » Wed Mar 05, 2008 6:35 am

ROCK SOLID wrote:My neighbour also has a spud gun and he said he can send a tennis ball over a mile :shock:


A load of bovine excrement if you ask me, unless you have an extremely high pressure,long barreled and quick valved pneumatic launcher.

Spraying butane into the tennis ball will have no effect whatsoever on performance, even if it does detonate and has a limited "jet" effect, since the projectile is spinning randomly it is irrelevant.
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Unread postAuthor: Jared Haehnel » Wed Mar 05, 2008 7:25 am

A load of bovine excrement


:shock:.... I love's Jacks humor

Thats a long way for a tennis ball considering it is light and has a rather high co-efficient of drag....


I agree with Jack only I think its more of a pile.... watch your step :D
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Last edited by Jared Haehnel on Wed Mar 05, 2008 11:11 am, edited 1 time in total.
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Re: making your progectile go further

Unread postAuthor: Ragnarok » Wed Mar 05, 2008 10:28 am

ROCK SOLID wrote:My neighbour also has a spud gun and he said he can send a tennis ball over a mile.

Jack has it in one. This is practically impossible, and your neighbour is spouting pseudoscience.
Filling a tennis ball with butane will not improve it's range. More likely, as it removes the pressurization of the ball in the first place, making it spongy, it will actually lose range.

Now, if you add some weight to the ball, by injecting it with water instead, that might help range, but no way is a mile possible with anything that can be practically built in a back garden.
I've not heard a report of more than around 500 metres range with an un-optimised projectile that I would believe, and normally, unless it was a seriously big-shot member that had claimed it, I would probably doubt claims of more than a 1/4 mile.

In this case, you have to ask how is he supposed to know it's gone a mile in the first place. He went out there and found it again? Hardly likely.
Nor could he watch it out there, then make an accurate range guess - at that distance, a tennis ball makes up only 0.15 of a minute of arc, which is like you being able to identify a small pea at 200 yards.

Get a demonstration.The ball probably won't go more than 200-300 yards, tops.

In this hobby, it's worth knowing that most people, unless they've had a lot of practise, will drastically overestimate range. Now, I've done calculations, and I know that with the right low drag projectile, I could almost certainly beat one mile range with some of my launchers, but I'd have one heck of a time proving it beyond all doubt.

What I ask is - do you need so much range? If you're firing that far, then you're probably firing out of your visual range, and that's potentially VERY dangerous. I won't fire anything unless I have a very good idea of where it's going to end up, and I know that area, and several radii out from there are going to be clear of innocent bystanders both for some time before and after firing.

The other thing is, it won't be much fun. The projectile will have to travel so fast you won't be able to see it's flight, and impact won't be visible - and that's not particularly entertaining.
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Unread postAuthor: SpudFarm » Wed Mar 05, 2008 11:09 am

rag you cant see it but it would do some damage...
but mabe if you make a big ass gunpowder cannon you have the chanse at mach 11 or something and then the ball would burn up. even a big hybrid cant get a mile with a tennis ball!
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Unread postAuthor: jackssmirkingrevenge » Wed Mar 05, 2008 11:20 am

I would say it's possible to send a tennis ball a mile a way without adding weight to it, if you launched it fast enough.

The pneumatic cannon on the USS Vesuvius for example had a maximum range of 5000 yards - throw something hard enough and it will go as far as you want it to ;)
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Unread postAuthor: jimmy101 » Wed Mar 05, 2008 12:47 pm

It doesn't look like it is possible to get a tennis ball to go a mile. Using Joanna's ballistic calculator (V2.2) and a Mach-1 tennis ball;

Mass: 57g
Diameter: 6.5cm (2.56")
Cd: 0.6
Optimal launch angle: ~20 degrees

Range: 133m (436ft)

Less than one tenth of a mile.

Anybody else have a ballistics calculator?

Heck, even the SpudWiki on tennis balls says the range is limited to about 137m.

The sectional density of a tennis ball is just too low to get a range of a mile. Doesn't really matter how fast you launch it.
jsr wrote:The pneumatic cannon on the USS Vesuvius for example had a maximum range of 5000 yards - throw something hard enough and it will go as far as you want it to.

That is only true up to a point. It doesn't matter how fast you launch an 12" diameter air filled ballon, it'll only go a couple feet. Tennis balls are basically small air filled balloons.
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Unread postAuthor: Ragnarok » Wed Mar 05, 2008 12:50 pm

spudfarm wrote:rag you cant see it but it would do some damage...

Indeed...

In fact, that's why you get few range claims from experienced spudders, but lots of damage pics. The projectiles are too fast to follow and find the range for, but they do hit hard and make nice messes on impact.

@ Jack: Without extra weight, to get said ball that far... it's going to need to be thrown at well over the maximum particle speed in the combusted gas. I'd go so far as to say it was impossible.

I've put in a velocity higher than the fastest ever projectile of significant mass (done by a plasma/electromagnetic combination no less, see my post in "Plasma power"), on my range calculator, and I still can't get a standard tennis ball to go a mile. The drag on a tennis ball is very high (as a deliberate design feature), the weight is pretty low, not a good combination.
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Unread postAuthor: jackssmirkingrevenge » Wed Mar 05, 2008 12:53 pm

But what if you launched it really really really really fast?

*puppy eyes*
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Unread postAuthor: Jared Haehnel » Wed Mar 05, 2008 12:56 pm

I've put in a velocity higher than the fastest ever projectile of significant mass



Did you stick it in at 36,000ft? Or at 72,000ft

Just for kicks and giggles....
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Unread postAuthor: Ragnarok » Wed Mar 05, 2008 12:58 pm

I got to 100 times the speed of sound and couldn't get a TB to go that far. Admittedly, my program isn't designed to handle those velocities, but surely we can tell it's impossible for any of us to manage such a feat.
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Unread postAuthor: jackssmirkingrevenge » Wed Mar 05, 2008 1:01 pm

Oh come on, surely at mach 100?
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Unread postAuthor: Jared Haehnel » Wed Mar 05, 2008 1:03 pm

Would a tennis ball be a tennis ball at mach 100?
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Unread postAuthor: SpudFarm » Wed Mar 05, 2008 1:11 pm

a tennis ball at mach 100 is a fire ball to the 100feet range until it is dust :)
then as rag said WE cant make a cannon to shoot a tennis ball 1mile.
that is impossible for us. mabe NASA or something could have done it with liquid hydrogen and oxygen:P
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