Projectile cannons

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Pheonix Starflare
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RE: Projectile cannons

Post by Pheonix Starflare »

Does the SS physics engine alter the momentum of the firing ship based on the recoil? A simple way to determine this is have the ship sitting still, and fire a few salvos forward. You should start moving backwards, assuming Sir Newton knew what he was talking about...
If not, perhaps that's an improvement for the next itaration of the SS physics engine.
"An optimist sees a glass half full, a pessimist sees a glass half empty and an engineer sees a glass thats twice as big as it has to be."

"What do you get when you cross a chicken and and elephant? Chicken elephant sine(theta)"
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Dragonlead
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RE: Projectile cannons

Post by Dragonlead »

Phoenix,

The answer to your question is no. However, I think it has to do with the mass involved. My Yamato is a glacier (mass: 375e4). On a lighter ship there might very well be an effect. When I command the beast, I let my victims come to me (spider-style). Therefore, I see no recoil effect. However, I pitted my beam Yamato against my spitball Yamato, just for comparison. I let the AI take the spitballer. I killed him, but died myself 4 seconds later because his last salvo was already inbound. In this case, even my glacier-like mass got moved around abit. That is why I think there might be a recoil effect.

To be a bit more technical. A mass driver is a basically a rail gun (as I understand it). The reaction you feel when firing a gun is because the gas generated by the burn (technically, the gun powder doesn't explode) pushes out in all directions equally. The bullet moves down the barrel because it is the path of least resistance, but we as the operator still feel the effects of the expanding gas and think "recoil", but it really has nothing to do with the bullet itself.
A rail gun on the other-hand uses powerful magnets and opposing polarities to generate velocity in a small (ish) object. Because there is no gas expansion, there is no "recoil". The item being propelled usually does not touch any part of the gun itself, so there is no kinetic energy transfer. The bottom line is that a "mass driver rail gun" creates no recoil.

V/R
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Pheonix Starflare
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RE: Projectile cannons

Post by Pheonix Starflare »

ORIGINAL: Dragonlead
0
To be a bit more technical. A mass driver is a basically a rail gun (as I understand it). The reaction you feel when firing a gun is because the gas generated by the burn (technically, the gun powder doesn't explode) pushes out in all directions equally. The bullet moves down the barrel because it is the path of least resistance, but we as the operator still feel the effects of the expanding gas and think "recoil", but it really has nothing to do with the bullet itself.
A rail gun on the other-hand uses powerful magnets and opposing polarities to generate velocity in a small (ish) object. Because there is no gas expansion, there is no "recoil". The item being propelled usually does not touch any part of the gun itself, so there is no kinetic energy transfer. The bottom line is that a "mass driver rail gun" creates no recoil.

V/R

OK, I hate to disagree (and get off on a physics tangent) but I must.
Yes, Mass drivers are synonomous (outside of any specific Sci-Fi where there may be a distinction) to
rail guns.
However, recoil is caused by these things called the 'conservation of momentum',/link] and [link=http://en.wikipedia.org/wiki/Newtons_laws#Newton.27s_Third_Law_:_Law_of_reciprocal_actions]'newton's third law'. This means that basically, no matter how two objects that started out moving together, end up flying apart, their momentum vectors (mass*velocity) add to zero (meaning equal in magnitude and opposite in direction). This is always the case, although stuff starts getting wonky up near c (the speed of light, 186,000 mi/sec or 300,000 km/sec). However, momentum (P) is conserved no matter what.
I know it can be odd to think that of a momentum or kinetic energy (1/2*mass*velocity^2) transfer without physical contact, but think about this:
A bar magnet is floating through space at constant velocity. Now, another bar magnet comes towards it, head on. Eventually both will stop, assuming their have the same momentums initially. Now, momentum was conserved because there were equal momentum vectors in opposite directions. You may ask, rightly, where all that kinetic energy went? Well, the bar magnets actually heat up a bit as the KE is 'absorbed' into the magnets as heat, I believe.
If one of the magnets has more momentum, then the system will, in the end, have a total momentum equal to the sum (adding) of the two vectors. Make one of the magnets massive enough, and you have your railgun/turret/BB. This means that its change in momentum is very small, assuming relatively light bullets and non-relativistic (not near c) muzzle velocities. However, it could add up. For example, as I recall, during the Apollo 13 incident, the astronauts weren't allowed to jettison any waste (urine pouches, etc) after the accident because it would alter their course too much.
Solar sails are entirely based on the principle of conservation of momentum: a huge number of very low (relatively speaking) momentum particles colliding with an object, over time, will grant that object a high momentum of its own.
Right....so...the point is, rail guns (as would any other projectile launcher (including lasers for that matter, tho their momentum would be very minimal)) have recoil.

Any other physics questions could be directed to me too, I suppose.

Sorry for the slight tangent, I just had to do it.
"An optimist sees a glass half full, a pessimist sees a glass half empty and an engineer sees a glass thats twice as big as it has to be."

"What do you get when you cross a chicken and and elephant? Chicken elephant sine(theta)"
Burzmali
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RE: Projectile cannons

Post by Burzmali »

As a further note, mass drivers get their name in part because the system can be used to "drive" a spacecraft. Theoritically, you could grab and asteroid, install a mass driver, and use the momentum generated from the ejecting pieces of the asteroid to propel your "ship".
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Dragonlead
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RE: Projectile cannons

Post by Dragonlead »

Phoenix,
Your tag line says you're in Boston. You aren't going to MIT or anyhting like that are you?[;)]

AS I've said before, I was a military history major for a reason. The observations from the game are still valid, but I won't argue physics with you, professor.

V/R
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Pheonix Starflare
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RE: Projectile cannons

Post by Pheonix Starflare »

ORIGINAL: Dragonlead

Phoenix,
Your tag line says you're in Boston. You aren't going to MIT or anyhting like that are you?[;)]

AS I've said before, I was a military history major for a reason. The observations from the game are still valid, but I won't argue physics with you, professor.

V/R

Haha. No. Actually, I'm not in Boston right now so much as that's where my home address is. I'm at CMU in Pittsburgh going for a MechE degree, as you may guess from the quotes in my signature.
I tend to correct/instruct whenever physics is involved, it's just some urge I get. The worst time was when my Sr Calc teacher didn't understand physics.
"An optimist sees a glass half full, a pessimist sees a glass half empty and an engineer sees a glass thats twice as big as it has to be."

"What do you get when you cross a chicken and and elephant? Chicken elephant sine(theta)"
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