Ultra High Altitude subsonic flight
One of the first projects I worked on was to do a feasibility study on an Ultra High Altitude (80 000 ft) subsonic, solar powered Autonomous UAV (the idea being tht once launched it would be perpetually aloft).
Using ESDU atmospheric models, I managed to generate a concept I remember it being feasible, but of course very critical (flying in the coffin-corner as the speed of sound and stall speed curves converge). At the time the maximum efficiency of solar cells were approximately 21%, and assuming a solar energy intensity of around 1000W/m2, the design was a very intersting balance between wing area, drag polar, and of course propulsive efficiency, coupled with structural possibilities.
The one area I did not pursue at that time was the choice of propulsion (ducted fan vs propellers). Of course this will be critical to propulsive efficiency, but I felt at that stage there were major developments brewing in solar cell efficiency, and it could mean that within the life cycle of development, much more would become possible.
As life goes I moved on before seeing fruition of this project, but these days I'm very curious of what has been achieved in recent times in this field. It's still an area that I'm very interested in.
Sduplessis 12:53, 18 August 2008 (UTC)
Last paragraph of your talk page[]
Ref your last para: Please try to see, again,
- http://engineering.wikia.com/wiki/User:Siafu OR
- http://en.wikipedia.org/wiki/Aerospace_Engineering
- to get an answer.
- Best is to try NASA and (related web pages), or in USA again (which you must have already done).
--Dore chakravarty 23:14, 18 August 2008 (UTC)