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lego sight

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: SEAKING9006 » Tue Oct 21, 2008 10:17 pm

How to accurately aim a pneumatic cannon, by me.

1: Obtain a Ti-83 series of calculator or download a simulator.
2: Download the SGBC from the theories/accessories forum. (I created a version for MirageOS!)
3: Using either GGDT or better yet, a chronograph, clock the muzzle velocity of your cannon.
4: Using the bubble level indicators found on level sticks, create a mount for your gun using protractors and sticks.
5: Using a compass, set the correct azimuth for the shot and using the SGBC, the angle.
6: Pray to god the mount doesn't break when you fire.

Viola! You just put a freaking potato downrange with greater theoretical accuracy than PVC should EVER be able to match. Good job.

:lol: :lol: :lol: :lol: :lol: :lol: :lol:
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Unread postAuthor: cannon monkey » Tue Oct 21, 2008 10:24 pm

thats very smart i wish i could have came up with that
good for u :)
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Unread postAuthor: jimmy101 » Wed Oct 22, 2008 11:25 am

Speaking: have you ever actually tried that? I would think the accuracy would suck big time, especially with a spud as the ammo. What would you use as the C<sub>d</sub> for a spud? IIRC, nobody has ever actually measured the C<sub>d</sub> of variously sized spuds.

To get even moderate accuracy your method would have to be changed to something like;


1: Obtain a Ti-83 series of calculator or download a simulator.
2: Download the SGBC from the theories/accessories forum. (I created a version for MirageOS!)
3: Using either GGDT or better yet, a chronograph, clock the muzzle velocity of your cannon.

3b: Find the where the previous shot hit the ground.
3c: Back calculate a Cd given the range, ammo characteristics (mass, length, diamater...), launch angle, etc.
3d: Load the calculated Cd into SGBC.

4: Using the bubble level indicators found on level sticks, create a mount for your gun using protractors and sticks.
5: Using a compass, set the correct azimuth for the shot and using the SGBC, the angle.
6: Pray to god the mount doesn't break when you fire.
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Unread postAuthor: SEAKING9006 » Wed Oct 22, 2008 7:10 pm

Meh. I don't use spuds anyway. I prefer golfballs. Besides, did you read the commentary on the thread for the SGBC? They were trying to add so many equations, they nearly took the curvature of the Earth into account! :lol: But anyway, as long as you use good ammo, accuracy will be fine.


Besides, the Cd for golfballs is on the wiki. :wink:
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Unread postAuthor: Ragnarok » Wed Oct 22, 2008 7:41 pm

SEAKING9006 wrote:Besides, the Cd for golfballs is on the wiki.

Only because Jimmy put it there in the first place!

You shouldn't ever take a Cd as solid, different brands or minor damage to the surface of the ball could cause quite a big difference.
Not to mention that even NASA struggles to get Cd values of any real accuracy, so I'm a little bemused as to why it's quoted as 0.299 rather than 0.3
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Unread postAuthor: SEAKING9006 » Wed Oct 22, 2008 7:52 pm

But really, is the Cd really going to matter more than ten feet of accuracy? And what's ten feet with a gun made of plastic? :lol:
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Unread postAuthor: Ragnarok » Wed Oct 22, 2008 8:34 pm

SEAKING9006 wrote:But really, is the Cd really going to matter more than ten feet of accuracy?

You might be surprised, the Cd is probably the most important factor in the equation.
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Re: lego sight

Unread postAuthor: F.E.A.R._Sniper » Wed Oct 22, 2008 8:58 pm

Demon wrote:the brown "tower"


what i call my schlong after a bad backdoor encounter
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Unread postAuthor: SEAKING9006 » Wed Oct 22, 2008 9:03 pm

Well, that is true.

But, we really can't do much better for accuracy than golfballs. (But Larda might be able to, of course. :lol: )
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Unread postAuthor: Ragnarok » Wed Oct 22, 2008 9:06 pm

SEAKING9006 wrote:But, we really can't do much better for accuracy than golfballs. (But Larda might be able to, of course. :lol: )

You're forgetting the possibility of spin on the ball - not to mention finned darts, which are the best hope we have of accuracy in a spudgun.
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Unread postAuthor: SEAKING9006 » Wed Oct 22, 2008 9:09 pm

Or a golf tee on the back of the ball.
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Re: lego sight

Unread postAuthor: jackssmirkingrevenge » Thu Oct 23, 2008 12:55 am

F.E.A.R._Sniper wrote:
Demon wrote:the brown "tower"


what i call my schlong after a bad backdoor encounter


Oh dear. Even I didn't think of that.
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Unread postAuthor: Hubb » Thu Oct 23, 2008 1:22 am

I'm 25 and still a fan of legos. Good job Demon. :wink:
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Unread postAuthor: jackssmirkingrevenge » Fri Oct 24, 2008 2:27 am

hubb017 wrote:I'm 25 and still a fan of legos :wink:


Same here, still have a bag full from my prepubescent years and they still come in useful, whether as adjustable jigs or even as structural components :D
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