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Muzzle Energy

A place to ask general spud cannon related questions.
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Muzzle Energy

Unread postAuthor: Fnord » Thu Nov 01, 2007 1:29 pm

Why am I getting 3 different answers from 3 different programs?

Projectile mass: 28 grams / .987 oz / 432.1 grains
Projectile velocity: 900 fps


EVBEC (live): 1450 ft-lbs
Some online calc: 781 ft-lbs
GGDT: 777 ft-lbs



GGDT isn't too far off, but why is evbec reading so abnormally high?
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 01, 2007 1:36 pm

GGDT is about spot on, your online calculator is there but not as accurate while EVBEC is way off.

edit: The evbec result is approximately twice what it should be, coincidence or maybe there's an error in the program formula?
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Unread postAuthor: Fnord » Thu Nov 01, 2007 1:57 pm

Damn, now I feel like I've been lying every time I've told someone the ME of one of my combustion guns.
Oh well. I guess I could still get the hybrid to do 700 ft-lbs. Wouldn't want to be holding it though.
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Unread postAuthor: boilingleadbath » Tue Nov 06, 2007 4:03 pm

Oh, not this again...

I did practically the same thing in EVBEC 1.4

Here is the problem:
1) I calculate the muzzle energy in joules
2) I convert (incorrectly) this into foot-pounds

Specifically, I'm dividing by .7376 instead of multiplying.

This means that all our European friends have been getting the correct answer... but we haven't.

Very sorry about that.
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