At 08:45 PM 2/10/2016, you wrote:
First 100km task flown autonomously (and all below 4000ft)
A commercial off-the-shelf RnR Products SBXC sailplane was outfitted
as a UAV and performed more than 100 test flights of the ALOFT
algorithm, with a nominal endurance of 3 min after a winchlaunch to
approximately 100 m altitude. A notable success was unofficially
breaking the cross-country soaring goal-and-return world record by
flying 97.2 km (60.4 mi) declared distance over approximately 4.55
hr. Best endurance demonstrated by the algorithm was 5.3 hr and best
range demonstrated by the algorithm was 113.4 km (70.47 mi) open
distance. There was no motor on the ALOFT sailplane for any of these
flights, so all the endurance and range performance clearly came
from flying in thermals
<http://www.dtic.mil/get-tr-doc/pdf?AD=ADA614555>http://www.dtic.mil/get-tr-doc/pdf?AD=ADA614555
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I plotted the polar for the model glider using the polar coefficients given.
Min sink is about 0.5 knots at 10 KIAS, best L/D is about 20 at 13
knots or so and 4 knots of sink at 25 KIAS.
Makes the speed look a fair bit better.
They ought to put the autopilot in a two seat sailplane and have the
human pilot follow the autopilot commands. Preferably with another
glider of the same type flying the same course.
Things to note: They use netto in the cruise to find the best air.
They seem to do a g compensated netto for climb too. This isn't quite
what you want as when climbing you want to climb fastest. This isn't
necessarily the same as being in the best air as the sink speed of
the glider through the air varies with G load(bank angle) although
the way their algorithm works it is effective. A human pilot will
only use the bank angle required to maximise climb rate. You all do
that don't you?
Mike
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