Well I gave a payload (gopro, 350-400grams with gimbal) and a duration (10 minutes), I'm not sure what else to say! The aircraft was completely controllable with no memorable handling differences apart from a very slightly reduced response to high thrust demands, but as we fly our platforms for stability rather than speed it wasn't something that we really noticed.
The thing is, at 10,000' you have to move a lot more air in order to maintain the thrust necessary to stay at altitude. This additional RPM requires more current and that cuts into your battery life. It would be an interesting comparison to run a number of drones at 10K' to see how they held up.
One of my colleagues has done some investigations into the effect of density on multirotor performance before.
I don't have time to run the model for this specific case, but from a similar case with a lower air density of 0.71kg/m^2 (40c at 4km altitude) a simple quad uses ~20% more power in a stationary hover than at sea level.
Interestingly at high flight speeds (15-20m/s) you could actually start to see power savings at this altitude, as the parasitic drag of the vehicle body is reduced.
There was a post on reddit/r/multicopter a while ago of prop thrust at different air pressures with the same current. It's pretty much exactly what you're asking for.
Assuming air pressure at 10000 ft is ~69kpa, and sea level is ~100kpa, there really doesnt appear to be much of a difference, except for medium-sized props, which had very interesting thrust outputs- gaining efficiency at low rpm and loosing a lot at high rpm.
Anyway, point being is a 250 class quad could pretty easily fly at 10000 feet. Not particularly well, but considering 1:4 (or even 1:8) thrust ratios arent uncommon with 250 class quads they could still pull it off.
Now, idk about bigger quads like the phantom/iris, their props have quite different geometries which probably act quite differently.
At 10000ft, pressure is around 30kpa. Using the data you provided in the link and assuming a quad weighs any were around 600-800grams with camera, the multi rotor will be flighting at near 100% power. Sustained flight time would be very limited.
>lot more air in order to maintain the thrust necessary to stay at altitude.
Not really... you need to move the same MASS of air, just more air VOLUME. Bigger props solve that problem, at the expense of moving a large prop (greater moment of inertia, slower acceleration).
Sustaining at higher altitudes requires a higher prop speed, but a lower prop torque. The difference in consumption is by drag, friction, electrical losses, and such.
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