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Description: Technical and general issues related to space flight. (Moderated)
 

rocket engine efficiency 
  why are rockets burning most of their fuel outside the engine ============================== ========= MODERATOR'S COMMENT: Not sure the evidence for this, but it's technical, so will permit so the question can get answered.
By Luiz Kuntz  - Dec 12 2011 - 3 new of 3 messages    

Suggestions needed: Condensing steam in space 
  I need something that s completely automated and can extract 100 tonnes of water per day from steam (does 100 tonnes of steam 100 tonnes of water?). This condenser, heat exchanger or whatever has to function realiably despite lots of dissolved solids in the steam, so it has to be highly resistant to fouling.... more »
By byblow  - Oct 11 2011 - 4 new of 4 messages    

SpaceX fully reusable launcher 
  I would love to hear opinions about Elon Musk's announcement re: a fully reusable, two-stage launcher. In this SpaceX animated video -- [link] -- the launcher reminds me of the Falcon 9; it looks like the first stage has nine engines. I would think SpaceX would need a much more capable launcher, perhaps... more »
By byblow  - Oct 1 2011 - 13 new of 13 messages    

HELP NASA CEA CODE 
  Vaibhav wrote... ...If you overexpand a convergent-divergent nozzle beyond ideal conditions (i.e., when Pexit < Patm), the exit velocity will indeed be greater than the ideal exit velocity. However, you need to account for the "base pressure" thrust loss, Aexit * (Patm - Pexit). This drag term grows with... more »
By Jeff Berton  - Sep 7 2011 - 1 new of 1 message    

HELP NASA CEA CODE 
  I am using Nasa CEA code for calculating Isp for different Ae/At ratios with chamber pressure of 1000 psi. Problem is Isp should have a peak at optimum expansion condition i.e. when Pexit= Patm but with increasing Ae/At ratios Isp's are increasing although the Pexit<Patm. Can anybody who has used the code help me ?... more »
By vaibhav  - Sep 3 2011 - 1 new of 1 message    

Venus: Creating Aerostat habitats and floating cities 
  Do we have the technology to build excavation equipment that can tolerate the temperature and pressure found on the surface of Venus? If we're going to build these - [link] , could we harvest the materials we need from Venus?... more »
By Bootstrap Bill  - Aug 26 2011 - 1 new of 1 message    

producing metal in space 
  What equipment, materials and amount of electricity are needed to produce steel (in space) from ores found on NEOs? Would there be a need to add carbon (as a reducing agent) during the refining process, or something with characteristics similar to limestone (I believe calcium oxide is the "active ingredient" in... more »
By byblow  - Aug 25 2011 - 6 new of 6 messages    

Electromagnetic caterpillar drive. 
  Robert Zubrin researched the idea of using large electro-magnetic fields to produce drag against the sparse interstellar medium. Found it would be a feasible way of slowing down an interstellar spacecraft. I'm wondering if a series of electromagetic fields switched on and off in a caterpillar like fashion could utilise this same drag to cause... more »
By Wayne Smith  - Aug 15 2011 - 1 new of 1 message    

freezing water in space 
  A friend of mine who's a physicist says water in a container (a tank or bladder) takes a long time to freeze in space because convection and conduction of heat can't occur in a vacuum. But surely water in a tank or bladder will eventually freeze in space if shaded from the sun, right? Can anyone tell me how long it would take? The water is distilled, so... more »
By byblow  - Jul 27 2011 - 6 new of 6 messages    

Question about Apollo Lunar Module 
  My friend's friend is one of those people who think that we never landed on moon and his reasoning is that the ascent stage of Apollo Lunar Module did not have enough fuel and/or power to lift-off from moon. I found these specs on wiki: [link] APS propellant mass: 5,187 lb (2,353 kg)... more »
By eddman  - Jul 20 2011 - 2 new of 2 messages    

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