52 replies to this topic

[Zero]

Which is scientifically inaccurate.

The MAC launches objects by pushing on them with magnetic force. The slug is "pushing" against the magnetic fields, which push it forward. This works because the station weighs so much more than the slug, so it gets pushed back less than the slug for the same delta-v


Thems the rules folks. Thus the laws of nature spake
Sent from my Moto X

The word you're describing is inertia, the station takes longer to get moving because its larger, but it will still move regardless and still needs a thrust vector. In Halo 2 and Halo 2A I forgot, but the SMAC muzzle is vented, which probably mitigates most recoil, and then the muzzle itself also recoils so the station doesn't have to, probably with some type of dampner tech.

[sloosecannon]

The word you're describing is inertia, the station takes longer to get moving because its larger, but it will still move regardless and still needs a thrust vector. In Halo 2 and Halo 2A I forgot, but the SMAC muzzle is vented, which probably mitigates most recoil, and then the muzzle itself also recoils so the station doesn't have to, probably with some type of dampner tech.

Correct - they will need something to counteract the recoil.

I can't think of a feasible way of absorbing the recoil without it eventually pushing the station backwards - vents don't really have any effect I could think of, and a dampener is essentially just changing how the delta-v is applied...

[MrChipps]

I can't be bothered to look it up now, but I seem to remember reading somewhere that smacs have thrusters that fire the same time as the gun.

[VDNKh]

 

I can't be bothered to look it up now, but I seem to remember reading somewhere that smacs have thrusters that fire the same time as the gun.

 

 

Those would have to be some big ass thrusters, as every slug has the same kinetic energy as the Chicxulub impactor.

[Zero]

Correct - they will need something to counteract the recoil.

I can't think of a feasible way of absorbing the recoil without it eventually pushing the station backwards - vents don't really have any effect I could think of, and a dampener is essentially just changing how the delta-v is applied...

Vents would distribute the ejecting gasses out the side so it isn't pushing the station backwards and rather pushing it side to side equally so it doesnt move.

[sloosecannon]

Vents would distribute the ejecting gasses out the side so it isn't pushing the station backwards and rather pushing it side to side equally so it doesnt move.

I don't think that works that way. I'd try to explain, but honestly, I'm waaaay too tired to right now for some reason....

[MrChipps]

Those would have to be some big ass thrusters, as every slug has the same kinetic energy as the Chicxulub impactor.

Nevermind

[sloosecannon]

Not really, most of the energy is projected forward with the shell due to it beeing much smaller and lighter than the whole station.

*grumbles under breath about physics education*

Hint: Newton's third law

[MrChipps]

*grumbles under breath about physics education*

Hey, I'm a political science major my knowledge of physics is limited and I'm just guessing here. Feel free to educate me, I want to learn.

[sloosecannon]

Hey, I'm a political science major my knowledge of physics is limited and I'm just guessing here. Feel free to educate me, I want to learn.

The energy (delta-V) is exerted on both sides of the action - The reason the station doesn't go flying off is because, due to its larger mass, the delta-V has less of an effect on the station's trajectory. It would still require an equal amount of energy to counteract the recoil though - it requires just as much energy to fix its trajectory

TL;DR: Terminology is really important.

[MrChipps]

The energy (delta-V) is exerted on both sides of the action - The reason the station doesn't go flying off is because, due to its larger mass, the delta-V has less of an effect on the station's trajectory. It would still require an equal amount of energy to counteract the recoil though - it requires just as much energy to fix its trajectoryTL;DR: Terminology is really important.

So I was right but used the wrong terminology?

Edit: but if the shell beeing pushed out by magnetic fields has much less mass than than the station doing the pushing wouldn't the station move significantly slower relative to the shell? And couldn't a thrust assembly be capable of counteracting the stations movement and maintain its original position if said assembly could produce enough thrust?

[VDNKh]

The energy (delta-V) is exerted on both sides of the action - The reason the station doesn't go flying off is because, due to its larger mass, the delta-V has less of an effect on the station's trajectory. It would still require an equal amount of energy to counteract the recoil though - it requires just as much energy to fix its trajectory

TL;DR: Terminology is really important.

Delta-V isn't the right form of energy here, we're dealing with mass and velocity. Newtons is the appropriate unit of measurement, or in this case Teranewtons.

 

 

 

So I was right but used the wrong terminology?

Edit: but if the shell beeing pushed out by magnetic fields has much less mass than than the station doing the pushing wouldn't the station move significantly slower relative to the shell? And couldn't a thrust assembly be capable of counteracting the stations movement and maintain its original position if said assembly could produce enough thrust?

 

Imagine, if you will, a 12 kilometer wide asteroid traveling 20 kilometers per second. This is about the force of the impactor that kill the dinosaurs. Now imagine that asteroid hitting the business end of a SMAC. That's the kinda of recoil force we're talking about here.

[sloosecannon]

Delta-V isn't the right form of energy here, we're dealing with mass and velocity. Newtons is the appropriate unit of measurement, or in this case Teranewtons.

Well it's the same end result - the velocity is changed

I'm fairly certain they're different terms for the same thing tbh lol

[sloosecannon]

Edit: but if the shell beeing pushed out by magnetic fields has much less mass than than the station doing the pushing wouldn't the station move significantly slower relative to the shell? And couldn't a thrust assembly be capable of counteracting the stations movement and maintain its original position if said assembly could produce enough thrust?

Yes, and yes it will. However, the thrust assembly still has to counteract the entirety of the force generated by the firing. The effect it has on the station is irrelevant to how powerful the engines have to be.
Imagine it this way - You run in to a giant metal box on a frictionless low-friction surface. You fly backwards, and the box goes the other way a little bit. Now, if you want to move the box back to where it was, you'll need to hit it with exactly the same amount of energy, just going the other way.
When you're in orbit. it has the same effect - if the station is so massive that the firing of the SMAC barely moves it, you'll need a huge amount of energy (equal exactly to the amount generated by firing) to move back into the same position as before.

EDIT: Tune in today to watch Sloosecannon forget what frictionless means...

[Crisiss]

You're forgetting the fact that it's a giant magnet shooting a chunk of metal. I'm not sure how much recoil there is to speak of.

This is a pointless argument since nobody even knows how the damn thing works.

[SiRD31M0S]

You're forgetting the fact that it's a giant magnet shooting a chunk of metal. I'm not sure how much recoil there is to speak of.

This is a pointless argument since nobody even knows how the damn thing works.

The only real mystery, apart from position maintenance, is how the energy from the ground-side generators is projected to the station. We have approximate knowledge of how the gun itself works. Railguns are a thing we already have.

[sloosecannon]

You're forgetting the fact that it's a giant magnet shooting a chunk of metal. I'm not sure how much recoil there is to speak of.

This is a pointless argument since nobody even knows how the damn thing works.

There is exactly the same recoil as with an explosive weapon.
Recoil is a side-effect of propelling projectiles. Unless it's a non-physical projectile, there will be recoil.

[WarthogRacingMan3]

The only real mystery, apart from position maintenance, is how the energy from the ground-side generators is projected to the station. We have approximate knowledge of how the gun itself works. Railguns are a thing we already have.

They probably use microwaves or lasers to transmit the energy. Also, your right about us already knowing how SMACs work, we know the concepts behind coilguns (which SMACs are) and some have already been built on the small-scale and small-power level.

[Zero]

I don't think that works that way. I'd try to explain, but honestly, I'm waaaay too tired to right now for some reason....

That's how muzzle brakes work in real life, the gases are ejected out the side and not the front so there isn't as much force pushing against your shoulder, but rather in equal and opposite directions out the sides of the barrel.

[Metanator]

Correct me if I'm wrong about all this, but aren't the SMACs stationed in space? In which case, there is no need to vent gasses as there wouldn't be any to begin with? A coilgun round doesn't have any propellant in it, so there should be no gaseous expulsions. Also, while the thing about conservation of momentum is correct, wouldn't Lenz's law make it so that the actual recoil received right after the shot be very little as it is distributed over a longer period of time? So it would actually be really easy to account for that with the adjusting jets they would already have on the station to keep it in geosynchronous orbit?