Re: [Paparazzi-devel] StratoBlimp, a challenging UAV project

[Tilman Baumann]

On 20/11/12 08:55, Hector Garcia de Marina wrote:


> Also remember that the air density is low at those altitudes, 
> therefore the "free fall period" (or lets say the control over your 
> vehicle is minimum) must be designed for do not let the UAV spins at 
> high velocities. Also you will reach a really high speed, the 
> fuselage must be really well made for preventing fluttering, probably 
> staying only at 3Kg as maximum could be an issue to solve.

This guy gets away with it on the cheap with simple foam wings.
http://www.gpsboomerang.com/content/view/34/42/

Perhaps spaceship one style feathering would make sense.
Not necessarily as a hinged wing. Maybe just with a piece of foam or a 
drogue chute that can be detached once lower speeds are reached.

> Also, high speed + high altitude is a bad combination for a common 
> GPS, but I guess for this stage, the most important thing is to 
> stabilize the vehicle instead of tracking a trajectory.
I guess you would have to test the GPS reaction. AFAIK they are required 
to switch off at high speed by export regulations (so they don't end in 
cruise missiles or rockets).
But will it come back when a low speed threshold is passed?

> About communications, you should have a direct path between your 
> ground station and your balloon or vehicle right? With a high gain 
> antenna on ground you should be able of communicate with your UAV. I 
> have seen many times live HD video
> from weather balloons, so the bandwidth should not be a problem.
Line of sight FTW. :)