spaceship design question: generating gravity

General physics and astronomy discussions not directly related to Celestia
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Post #21by psCargile » 19.04.2007, 00:20

Ran across this doing a search for something else and it reminded me of a design that I came up with.




This is an attempt to solve the two axes of acceleration problem, but it does add mass due to redundancy. The translation tube should be designed to afford access in micro-gravity and with hand rungs and/or a lift platform. The center red rooms are for thrust acceleration. The centrifugal green rooms are accessed under micro-gravity conditions by use of a ladder to a scaffold and to the floor by staircase.

On the issue of g forces experienced in flight, in a steady, coordinated turn the g-force is equal to 1 over the cosine of the bank angle. The greater the bank angle, the greater the gs. Also, the greater the speed, the larger the turn radius ( velocity squared over 11.26 times the tangent of the bank angle in knots and degrees), which makes Mach speed dogfighting ridiculous and limits it to subsonic speeds. But the g-forces felt are under the influence of the earth's gravity. The g-forces are a "weight" so gravitational attraction is a component. This will differ in space under micro-gravity conditions. Consider the orbital speeds of the Space Shuttle, around 17500 mph, and the maneuvers it executes on orbit. If it could perform the same maneuvers in the atmosphere under gravitational influence, it would pin crew to the walls and most likely kill them. The new inspection procedure prior to docking with the ISS has the Shuttle perform a turn that has a very small radius in relation to its speed and the turn radius formula above doesn't apply. The pitch roll doesn't add enough acceleration to worry about and the crew perform the maneuver floating in the cabin and not strapped down in the seats.

The accelerations forces that space borne fighters would experience are different that those felt in gravity. A space fighter wouldn't have to constantly accelerate and can cruise at a constant speed and can change attitudes without a change in flight direction with very little acceleration forces. A vector change would result in acceleration forces, but it is doubtful to me that any acceleration that is necessary for combat maneuvers would have to be over nine g's. And I'm not convinced that for a small mass fighter the acceleration would have to be up to one g.

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Post #22by MKruer » 24.04.2007, 09:16

I believe that you could make it work providing that you fully balance the system along any give axis. The simplest one would probably be with 3 rotation sections, two of them would be spinning the opposite way from the larger central one. Because main hub would be along the x axis, that should eliminate the roll torque. Because you have equal masses spinning in opposite along the y and z axis?€™s that should eliminate the ships willingness to yaw and pitch. You could do it with two but one of them would have to be inside the other to work. The beauty of the 3 wheel design is that you could adjust the speed of each of the wheels slightly to maintain a constant balance.

But to answer the first question yes you can have a flat ship and you would only need two moving sections but one of them would have to be inside the other, not side by side as was originally specked.

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Post #23by Growler » 22.07.2007, 04:09

The movie mission to mars had what appeared to be a relatively simple system, a rotating hab ring with a zero gee lab and control deck.

This system would make sense considering when you think about present technology, since nothing we have available today could provide any acceleration that would possibly interfere with the spinning hub.

The problems with spin induced artificial gravity would occur when the speed of the vessel begins to equal the force caused by the spin
We are all born as molecules in the hearts of a billion stars.

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Post #24by LordFerret » 22.07.2007, 07:04

What comes to my mind is two sets of synchronized counter-rotating swing-like habitat pods... much akin to the amusement park chair swing (see picture in link below).

The chairs are the habitat-pods. The way you see them in the picture, would be during acceleration... or, for deceleration they'd be facing up. During coast they're rotating to produce 1g. Their rate of rotation changes during acceleration/deceleration in synchronization with engine thrust... the balanced combination of varied rotation and thrust providing a constant 1g. The occupants would never know (feel) movement.

Great for moving in a straight line. Course changes would be a different story however. 8O I'll have to work on that one. :lol:

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Post #25by eburacum45 » 28.07.2007, 12:42

The problem only comes during acceleration; when the ship is not accelerating it is essentially in free fall, so the centrifugal gravity is normal to the axis of rotation.
Just stop the rotating sections during acceleration and you will be fine- Clarke suggested this could be done using counterrotating flywheels.

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Post #26by LordFerret » 29.07.2007, 03:55

As was mentioned about A. Clarke's Rama cylinders, or any 'fixed' wheel or ring... what happens to the habitat contents when the rotation is stopped for acceleration / deceleration? It's all going to slide one way or the other. Can you imagine trying to build and maintain a mini-world within such a gigantic cylinder (buildings, dirt, trees, lakes, people, animals)... and then stop its rotation so you could fire the engines? I see a very big mess inside. :? Hence, my previous post. :wink:

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