Comments on: Ep. 101: Advanced Propulsion Systems http://www.astronomycast.com/space-flight/ep-101-advanced-propulsion-systems/ Take a weekly facts-based journey through the cosmos with Astronomy Cast. Tue, 16 Mar 2010 02:48:39 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: home made wind generators http://www.astronomycast.com/space-flight/ep-101-advanced-propulsion-systems/comment-page-1/#comment-2340 home made wind generators Sat, 27 Jun 2009 06:59:17 +0000 http://www.astronomycast.com/?p=353#comment-2340 Great stuff=D Will definitely visit soon/ Great stuff=D Will definitely visit soon/

]]> By: Jay Parkhill http://www.astronomycast.com/space-flight/ep-101-advanced-propulsion-systems/comment-page-1/#comment-669 Jay Parkhill Thu, 28 Aug 2008 17:03:13 +0000 http://www.astronomycast.com/?p=353#comment-669 Listening to this pair of posts reminded me of a question someone posed to me a while ago and I have never understood the right answer to. Though it is not strictly astronomy-related I don't know anyone more qualified to give a definitive answer than you. If you two are able to set my mind at ease I would be grateful. The question is: if an airplane is set on a giant treadmill and the engines fired for take off, but the plane never moves relative to the ground, would it take off? I have seen people argue persuasively that (i) yes, it would because of the force generated by the engine, and (ii) no it would not, because a plane requires air moving under/over its wings to generate lift and the treadmill prevents the air from moving. I fall in the (ii) camp, but I would love to hear an answer from someone who actually understands physics! Thanks very much, Jay Listening to this pair of posts reminded me of a question someone posed to me a while ago and I have never understood the right answer to. Though it is not strictly astronomy-related I don't know anyone more qualified to give a definitive answer than you. If you two are able to set my mind at ease I would be grateful.

The question is: if an airplane is set on a giant treadmill and the engines fired for take off, but the plane never moves relative to the ground, would it take off?

I have seen people argue persuasively that (i) yes, it would because of the force generated by the engine, and (ii) no it would not, because a plane requires air moving under/over its wings to generate lift and the treadmill prevents the air from moving.

I fall in the (ii) camp, but I would love to hear an answer from someone who actually understands physics!

Thanks very much,
Jay

]]> By: Robert http://www.astronomycast.com/space-flight/ep-101-advanced-propulsion-systems/comment-page-1/#comment-639 Robert Thu, 14 Aug 2008 17:45:44 +0000 http://www.astronomycast.com/?p=353#comment-639 I loved this episode, but was hoping to hear a little about the space elevator. I know it's not really a 'propulsion' technology, but it would (in theory) get us into orbit. Happy triple digits! I loved this episode, but was hoping to hear a little about the space elevator. I know it's not really a 'propulsion' technology, but it would (in theory) get us into orbit.

Happy triple digits!

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