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yamamushi

Reaction Wheels and Magnetorquers

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As an alternative to RCS and having to rely on spending fuel to adjust orientation (Attitude control) in space, I propose the addition of two alternative systems that rely on different sources of energy.

 

The first would be a reaction wheel:

 

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A reaction wheel (RW) is a type of flywheel used primarily by spacecraft for attitude control without using fuel for rockets or other reaction devices. They are particularly useful when the spacecraft must be rotated by very small amounts, such as keeping a telescope pointed at a star. They may also reduce the mass fraction needed for fuel. This is accomplished by equipping the spacecraft with an electric motor attached to a flywheel which, when its rotation speed is changed, causes the spacecraft to begin to counter-rotate proportionately through conservation of angular momentum. Reaction wheels can rotate a spacecraft only around its center of mass (see torque); they are not capable of moving the spacecraft from one place to another (see translational force). Reaction wheels work around a nominal zero rotation speed. However, external torques on the spacecraft may require a gradual buildup of reaction wheel rotation speed to maintain the spacecraft in a fixed orientation.

 
 

https://en.wikipedia.org/wiki/Reaction_wheel

 

Think of a reaction wheel as a moderately large disk that spins at incredibly high speeds, and is set on an axis of an object. Because of Newton's 3rd law (applicable here as the conservation of angular momentum), if you apply a change in the direction or speed of the spinning disk, the attached object will move proportionally along the axis of the disk. 

 

If you apply a reaction wheel to all 3 axes (X, Y, Z - and yes "axes" is the plural of "axis"), you can adjust your orientation completely using electric energy.

 

 

Additionally, there is the maqnetorquer:
 

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A magnetorquer or magnetic torquer (also known as torque rod) is a satellite system for attitude control, detumbling, and stabilization built from electromagnetic coils. The magnetorquer creates a magnetic field that interfaces with an ambient magnetic field, usually Earth's, so that the counter-forces produced provide useful torque.

5

https://en.wikipedia.org/wiki/Magnetorquer

 

This post does a really good job of explaining how they work (and really isn't as math heavy as the question would lead one to believe): https://space.stackexchange.com/questions/2239/what-is-the-math-behind-magnetorquers 

 

 

 

And for those that don't want to do a lot of reading, here's a short video that covers this topic:
 

 

 

 

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I do hope they implement different types of elements with different advantages and drawbacks (not only for RCS, but for every element) so a player needs to decide which to use.

 

To me, reaction wheels would make more sense for DU because they just work everywhere (unlike the magtorq) and would add great immersion to the game

 

that post rly is nice to read, well explained

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I think Magnetorquers would be more useful for space stations in orbit around a planet. Since they're in range of the planet, perhaps they could rely on the planet's magnetic field for stabilization without having to expend an insane amount of fuel for RCS orientation. As for use on ships, I can't see them being incredibly useful there. 

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Introductions? Who needs introductions?

 

RCS: advantages: can do both rotation and translation(moving), very responsive on small craft. Disadvantages: requires fuel.

 

Reaction Wheels: Advantages: needs only electricity, good for fine-tune rotations. Disadvantages: requires one on each axis. There is also reaction wheel saturation where the reaction wheel can spin no faster because it spins really fast while rotating due to newton's 3rd(?) law.

 

Magnetorqures: Advantages: needs only electricity, good for fine-tune rotations Disadvantages: needs a magnectic field to work. Not all celestial bodies have magnetic fields.

 

I want to talk about Electrodynamic tethers.

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As part of a tether propulsion system, crafts can use long, strong conductors (though not all tethers are conductive) to change the orbits of spacecraft. It has the potential to make space travel significantly cheaper. When direct current is applied to the tether, it exerts a Lorentz force on the magnetic field, and the tether exerts a force on the vehicle. It can be used either to accelerate or brake an orbiting spacecraft.

 

-Wikipedia.

 

BTW, the channel of the video that the OP posted is called Vintage Space. Its a great channel, recommend checking it out.

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I certainly hope these are a thing! After all you typically use a combo, not just flat out one or the other; Redundancy is key!

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