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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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Unread postAuthor: jackssmirkingrevenge » Wed Mar 05, 2008 1:21 pm

I'm not asking if *we* can do it, but if it can be done.
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Unread postAuthor: Jared Haehnel » Wed Mar 05, 2008 1:51 pm

"If" , in the vacuum of space, on the moon, on mars, or in high orbit it very well could be done.... but on earth at "normal" atmosphere... perhaps if we launched it really high with a good stiff tail wind and if an eagle perhaps carried it for a few extra feet....

Of course this is my attempt to be sarcastic not offensive.... :wink:

Surely it could, in "theory", be done.... or perhaps Rag is wrong with his calculus ...mach 100 seems very fast and it would take an object moving at that fast a long time to slow down even if it has a low mass and a high drag co efficient...

Honestly I've got no idea... but I would think that it could very well be likely but ...if Rag is right it would have to be moving dang fast! I've heard crazier things...
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Unread postAuthor: starman » Wed Mar 05, 2008 2:49 pm

jackssmirkingrevenge wrote:I'm not asking if *we* can do it, but if it can be done.


The TB lack of mass vs its large size and therefore it's drag coefficient in air would be the force dominating the calculation...same reason you couldn't shoot a ping pong ball a mile no matter how high the initial velocity.
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Unread postAuthor: POLAND_SPUD » Wed Mar 05, 2008 2:53 pm

what is the cd of spheres such as a TB?
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Unread postAuthor: Fnord » Wed Mar 05, 2008 3:06 pm

Probably around .55 to .6

If you shot a tennis ball fast enough to go a mile on earth it would just burn up. All the kinetic energy is being turned into heat by friction, and a 50 megajoule shot would probably be enough to initiate a fusion reaction in the tennis ball :)

In space however, you could just throw it. Ask your neighbor if he used to work for nasa.
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Unread postAuthor: Ragnarok » Wed Mar 05, 2008 3:24 pm

jackssmirkingrevenge wrote:Oh come on, surely at mach 100?

No, not even when it goes that fast - the calculator isn't designed for these speeds though, but doing the best I can, all that extra speed is scrubbed off in only a few hundred metres - the deceleration is vast. The friction would actually cause the ball to incinerate, but ignoring that...

After those initial 200, up to maybe 400 metres (if you account for possible error at those speeds), the tennis ball is once again subsonic, and adding on those 400 metres (plus of course some elevation) to a regular TB shot, it's hard to account, even with slightly generous parameters for more than about half a mile to a kilometre, even with a Mach 100 launch.

So I would say, no, I really don't think it can be done.

Getting it near fast enough would be impossible, speeds that would allow it to go that far would cause it to burn up, and it would probably get you arrested.
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Unread postAuthor: jimmy101 » Wed Mar 05, 2008 4:19 pm

OK, here is how you fire a TB ball to a distance of a mile;
1. Take a 105mm Howitzer round
2. Cut in half
3. Hollow out a TB sized cavity
4. Insert TB
5. Superglue the two halves of the shell back together ( :roll: )
6. Fire mod'd shell from 105mm howitzer
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Unread postAuthor: jackssmirkingrevenge » Wed Mar 05, 2008 4:25 pm

jimmy101 wrote:OK, here is how you fire a TB ball to a distance of a mile;
1. Take a 105mm Howitzer round
2. Cut in half
3. Hollow out a TB sized cavity
4. Insert TB
5. Superglue the two halves of the shell back together ( :roll: )
6. Fire mod'd shell from 105mm howitzer


Best answer all day :D now *that's* the sort of can-do attitude spudders need, bravo!
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Unread postAuthor: DYI » Wed Mar 05, 2008 4:34 pm

And the best part is, the TB isn't transformed into ash as soon as (or before) it leaves the barrel :D (unless the superglued howitzer shell doesn't take very well to being fired from a howitzer, but I think a lot more than the tennis ball would be incinerated in that case :roll: )
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Unread postAuthor: Ragnarok » Wed Mar 05, 2008 6:01 pm

jackssmirkingrevenge wrote:Best answer all day :D now *that's* the sort of can-do attitude spudders need, bravo!

It achieves it in strict terms, but not in the spirit of the idea...

If you filled said TB with the right material, it would certainly have the weight to allow it to be thrown that far without impossible velocity requirements.
Still, injecting water into a tennis ball doesn't add enough weight to make a mile a practical range. Even with a Mach 1 launch, it's only got enough oomph for 400 or 500 metres.

With the highest practical muzzle velocity we are likely to be able to achieve, perhaps 300 m/s, the weight needs to be approaching 2 lbs to get a projectile with the size and drag of a tennis ball out to a mile.
For that, you'll need to inject it with mercury, and have around 30000 ft-lbs of energy.

And then I'd be more entertained seeing that hit a target for damage, rather than trying to lob it a mile.

So, DYI - fancy a summer project(ile)?
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Unread postAuthor: DYI » Wed Mar 05, 2008 6:41 pm

So, DYI - fancy a summer project(ile)?


*Runs off to GGDT*
Yep, I'll be able to do it if I can get 2.5" pipe in Canada somewhere. Not with the SCTBDC, but the [redacted] project should be able to achieve it without much trouble, if not quite safely.

My real question is, why would you even want to send a TB a mile? You'd never find it unless it had an imbedded GPS receiver, and you'd certainly never see it in flight at ~1 000 fps. By the way, the appropriate amount of tungsten balls would be less difficult and toxic than mercury.
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Unread postAuthor: clide » Wed Mar 05, 2008 6:52 pm

DR from the Spudtech forums (who has always seemed rather trustworthy) had some pretty impressive TB range figures from one of his hybrids. IIRC they were near a mile for water filled tennis balls. Anyone else remember that?

Edit: After some digging it was over a mile but he was never able to reproduce it so he doubts the figure. He was able to consistently shoot about half a mile. I couldn't find the actual thread but I did find a few references to it.
http://www.spudfiles.com/spudtech_archi ... 957#p59957
http://www.spudfiles.com/spudtech_archi ... 934#p61934
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Unread postAuthor: iknowmy3tables » Wed Mar 05, 2008 7:26 pm

the whole butane in tennis ball is not likely to improve preormence but I saw a pic of sgort shooting a caulking tube from a combustion in the dark, there was a little extra aerosol in the tube, it made a cool glow as it was flying in the air
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Unread postAuthor: STHORNE » Wed Mar 05, 2008 8:23 pm

iknowmy3tables wrote:the whole butane in tennis ball is not likely to improve preormence but I saw a pic of sgort shooting a caulking tube from a combustion in the dark, there was a little extra aerosol in the tube, it made a cool glow as it was flying in the air


Yeah, it doesn't enhance performance....it enhances entertainment :happy1:
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Unread postAuthor: bigbob12345 » Wed Mar 05, 2008 8:31 pm

entertainment is the purpose of spudding so any thing that enhances entertainment such as performance is worth doing :)
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