On Wednesday, April 1, 2015 at 5:47:39 PM UTC-4, Bill D wrote:
On Wednesday, April 1, 2015 at 2:33:12 PM UTC-6, son_of_flubber wrote:
This approach is cleaner

http://www.youtube.com/watch?v=zpluCYve9qw&t=5m32s

OK, with full recognition that it's April 1st, an electric ducted fan has some advantages for self-launch in that ~60 knots is right in the middle of the "sweet spot". It could beat any open prop's thrust/Watt ratio at that speed.

I think the best use for this toy would be as a single-use emergency sustainer. It develops 5.5 kg maximum thrust, 12 lbs of thrust... say 10 lbs for hand waving ease.

So an 800 lb gross weight glider with L/D 40:1 requires 20 lbs of thrust to sustain altitude. Add one of these 'toy' engines for 10 lbs of thrust would in turn give the glider an equivalent L/D of 80:1 while the turbo was running. Run it intermittently while flying between thermals. Turn it off and let it cool while you climb in the thermal. Add 2 turbos for redundancy. Run both and you have an intermittent use sustainer. It pushes on the airframe with a force of 10-20 pounds.

Power from Duracells Alkaline batteries. Cheap. High energy density and a long shelf life.