|MadSci Network: Physics|
First question In a site about flying contraptions there's a page showing a drawing of a thing that they call "jet belt" (http://www.shreve.net/~jnuts/fly/old/jetbelt.html). My question is: would a "jet belt" built like that really be able to take off? I'm asking this because, as you can see, the air enters the turbine from down and the gases are ejected towards down too. Shouldn't the resulting forces be opposite and therefore cancel each other? Your reply Dear Simone Yes, a 'Jet Belt' is possible and does work. The point is that the incoming air is accelerated in the jet engine. The relevant physical property is the "momentum" i.e. velocity times mass. A mass m of air enters the engine with a velocity v, say every second. This mass is ejected with a velocity much higher than v and this results in an upwards force. All in all, it works just like a normal jet engine (the mass of the fuel plays an additional role). My Question Looking at the jet belt design, would it require some form of stabilisation or gyros? If so how does a gyro keep it stable? How would you steer a jet belt? Or is it just a matter of getting the centre of gravity in the correct place, thanks!
Re: jet belt design, would it require some form of stabilisation or gyros?
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