### Author Topic: Future Space ship technical Q&A  (Read 2411 times)

#### arianabedi

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##### Future Space ship technical Q&A
« on: 07/29/2010 06:52 PM »
To start off with the first question,

How would a space ship do yaw,pitch or roll in zero gravity (as in non orbital zones)?

*my own guess*
It would have small "propellants" on the bottom, top and sides of its fuselage, and to for example the spaceship would do a pitch up rotation via its bottom propellants pushing the tip of the spaceship up (assuming the spaceship resembles a plane and the propellant is location near the tip of it) while its mail propellants push it forward, thus combining to result in an upward pitch.
My own assumption would be false if forces in free fall or no gravity zones act on an object independently (as in the whole ship simply moves upwards and forward at the same time, without any rotation.).

If i have posted this thread in the wrong section please notify me.

A

#### Jim

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##### Re: Future Space ship technical Q&A
« Reply #1 on: 07/29/2010 07:02 PM »
To start off with the first question,

How would a space ship do yaw,pitch or roll in zero gravity (as in non orbital zones)?

By using thrusters or reaction wheels like most interplanetary spacecraft already do.

What you do mean by "propellants"?
« Last Edit: 07/29/2010 07:03 PM by Jim »

#### arianabedi

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##### Re: Future Space ship technical Q&A
« Reply #2 on: 07/29/2010 07:07 PM »
Dear Jim,

As far as i know ( and i know just about nothing) flywheel or reaction wheels are for very small changes in angular momentum.

By an spaceship rotation i ment more like how a plane rotates, well that is if "future" spaceships would rotate in that manner at all.

Maybe my ideas are flawed because they are mixed a bit with scenes seen in movies. Never the less, kindly explain a bit more on this matter.

one more thing, does the reaction wheel use the "action/reaction" law to rotate?

#### arianabedi

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##### Re: Future Space ship technical Q&A
« Reply #3 on: 07/29/2010 07:15 PM »

[/quote]

What you do mean by "propellants"?

[/quote]

Im so sorry, i forgot to actually check what i was writing, propellant is actually the "fuel" i actually ment a thruster.

#### Jim

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##### Re: Future Space ship technical Q&A
« Reply #4 on: 07/29/2010 07:28 PM »
Almost every spacecraft use thrusters to change attitude and the few that don't use reaction wheels/control moment gyros

They use them whether in orbital or interplanetary space.  It doesn't matter whether they are in free fall.

http://en.wikipedia.org/wiki/Attitude_dynamics_and_control

http://en.wikipedia.org/wiki/Reaction_control_system

#### sitharus

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##### Re: Future Space ship technical Q&A
« Reply #5 on: 07/29/2010 07:32 PM »
Dear Jim,

As far as i know ( and i know just about nothing) flywheel or reaction wheels are for very small changes in angular momentum.

By an spaceship rotation i ment more like how a plane rotates, well that is if "future" spaceships would rotate in that manner at all.

Maybe my ideas are flawed because they are mixed a bit with scenes seen in movies. Never the less, kindly explain a bit more on this matter.

one more thing, does the reaction wheel use the "action/reaction" law to rotate?

Reaction wheels can make any difference to angular momentum perpendicular to the axis they rotate around. The change is proportional to the wheel mass and speed delta.

How do you mean "like a plane"? If you mean like Star Wars and its ilk, no, there's no point, you can always freely rotate around any axis without changing your velocity vector.

If you want to see something a tad more realistic watch Babylon 5, in particular how the Star Furys move.

Reaction wheels use conservation of angular momentum to make changes. They do have limitations, so you generally have thrusters to make up for this. Thrusters work best when off axis, look at the RCS thrusters on the space shuttle orbiter for an example of positioning.

#### arianabedi

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##### Re: Future Space ship technical Q&A
« Reply #6 on: 07/29/2010 07:35 PM »
Dear jim: Thank you for the links, great info! and thnx for explaining.

Dear sitharus: i shall check the movie scene, visual explanation is the best after all. Also thank you for the explanation

Tags: Spaceship  space  ship