# Why don't we build helicopter based space shuttles?

As seen in this video: the principle of the helicopter does work in space. So we could make a helicopter based space shuttle! It would be easier to navigate with it than with propulsors.

the video show that the principle of helicopter works in a zero-g (no gravity) environnement, not that the principle works in space.

The helicopter is able to lift on earth (and int the space shuttle) because of the viscosity of the air. Whitout any friction, there is no move. In space, there is really few particles. So the friction would be very low and you cannot use system such as helicopter.

An helicopter in space would be like trying to use à boat turbine in air

• It is mostly the density of the air that matters - not so much the viscosity. You need to "push matter one way" in order to create an impulse in the opposite direction. If there is no "stuff to push", there will be no force on the blade. Viscosity is a given for all (non superfluid) substances - density is the key. – Floris May 13 '15 at 12:47
• Sorry but I disagree. If you move a blade with a certain angle of attack at a certain velocity, you will hit molecules in the medium and change their direction. This change in momentum translates to a force on the blade. You can call it "friction" but you can have friction without lift (for example when the angle of attack is 90°). The change in momentum of the air (medium surrounding the propeller) results in lift. viscosity does not depend on density – Floris May 13 '15 at 13:05
• When I was an undergraduate, we got to play with superfluid He. We spun a paddle wheel to stir the He, and watch it move a second paddle wheel. It was amazing how the second paddle wheel sat still when below the critical temperature. – mmesser314 May 13 '15 at 13:07
• Viscosity is certainly an important component in designing a lifting surface but the fundamental problem for a propeller driven system in space would be the simply lack of any reaction mass to use. Hellicopters use lift which is the reaction from pushing air the other way. Nothing to push on means no lift. That's why rockets carry their own reaction mass along. – dmckee --- ex-moderator kitten May 13 '15 at 14:32
• Can airplanes fly in no atmosphere? Of course not. There's nothing for the wing to react against. A helicopter rotor is just a wing that goes in a circle. (They are called "rotary wing aircraft".) – Mike Dunlavey May 13 '15 at 19:15