Contra-rotating Sections on a large ship!

[Epsilon]

Basically, I have this:
http://www.etmoonshade.net/donovan.jpg

The two big "wheels" are the classical rotating sections on a long-haul space ship, to create a sort of 'gravity'. The question is, assuming they're rotating in opposite directions, have the same mass, and rotate at the same speed, would it introduce a torque in the ship, causing it to turn? I don't -think- it will, but I figure that someone out there could answer me for sure.

By the way, material strength, etc. isn't a part of this question. The strength of the materials in my ships are exactly enough to easily handle any stresses put upon that ship. It makes for slightly easier design.

 

[Imagineer]

The two big "wheels" are enormous gyros. As long as no torque is applied to the ship, the gyros will not intoduce any torque at all. If you use RCS thrusters to attempt to turn the ship, however, the gyros will introduce a torque which opposes the turning torque. See Spin Stabilization and Gyroscope.

 

[Andy44]

If they're rotating in opposite directions, won't the net angular momentum be zero?

 

[unknown_orbiter]

If they're rotating in opposite directions, won't the net angular momentum be zero?

bingo
BTW Eps I see you are using Blender. Good choice

 

[Epsilon]

If they're rotating in opposite directions, won't the net angular momentum be zero?

I think that was the question I was asking. Keep in mind, I'm far from being a physics major - I managed to fail it in High School, in fact. On the other hand, I think I've got a good grasp on the -theory- behind it. ^_^

Now, another related question - if the "gyros" are off the center of mass, wil that toss things out of whack?

I'll look up gyroscopes after the post, but it won't hurt to toss the question here while I'm replying, will it?

bingo
BTW Eps I see you are using Blender. Good choice

Yes. Yes it is.

 

[IjonTichy]

Now, another related question - if the "gyros" are off the center of mass, wil that toss things out of whack?

There is no wobble if the common rotation axis of the two "gyros" coincide with one of the principal axes of inertia of the ship.

 

[Epsilon]

Speaking of rotating gyros... I've been testing the ship I'm making (god help me, I'm going to eventually have to do a .dll file so the RCS linear thrusters aren't better at moving the ship than the main system...) and I was peering at the Lunar wheel base.

This got me to thinking - what rotational period would create (roughly) 9.8m/s^2 "gravity" at the edges of the station? The way I figure it, a point on the outside of the 500m "wheel" would be moving at a bit over 39 m/s (it's got roughly a 40 second rotational period), but I'm not entirely sure what direction to go in after that, as far as calculating what the centripetal force would be at that point. I'm also not sure if I'm using the right terminology here.

The reason I'm asking this is because I'm trying to figure out what rotation I should apply to said "gyros" to create an earth-like gravity at the outside of -my- wheel.

I'm honestly not sure if this should be in "space math" or in "addons" at this point, since I'm getting more specific, but this -seems- to be appropriate for the section. :lol:

 

[Zatnikitelman]

http://www.calctool.org/CALC/phys/newtonian/centrifugal
Try that site. Just plug the values in and away you go.

 

[Epsilon]

Very cute (and useful) site.
You sir, are win. I lift a glass to you.
Amusingly enough, I've got a site like this that I use for my own calculations, but it doesn't have anything like that. Maybe I should change over...