On Tue, 11 Dec 2018 13:27:00 -0800, ktr wrote:

This could also spark a battery "arms race". Now not only would pilots
need to fork over the big bucks for the latest and greatest air frame,
they would also need to spend big bucks on the biggest, baddest battery
available.

Not necessarily. Here's what happens in the model world.

If they take even a passing look at how electric power is used in model
competition classes (F1Q free flight and F5B radio control) they use
onboard energy limiters. Exactly what the limiter does depends on the
class:

In F1Q the model climbs under power until either 30 seconds has elapsed
or the motor has chewed through its power limit (4 joules per gram of
model weight). The first of these to occur ends the motor run and the
model continues in gliding flight until it lands or maximum flight time
for the event is reached. Competitors are scored on the total flight time
they achieve over a set number of flights.

In F5B each flight is multitask: the model first flies laps round two
pylons for 2 minutes after which it is expected to soar for a further 10
minutes, ending with a spot landing. The flight is scored on the number
of laps flown, the difference between the soaring flight time and 10
minutes (the difference between actual flight time and 600 seconds
reduces the score) and the distance the model lands from the spot (the
closer to the spot it stops, the higher the score). There is an energy
limiter in the model that shuts the motor down as soon as the energy
limit is reached and prevents it starting again during that flight.

In view of this CIAM experience (CIAM is part of the FAI) I wouldn't
expect any electric manned glider class to have a hard limit on power
used, but I *would* expect every glider to carry a sealed energy logger
fitted between battery and motor and for this log, which might be
included in an enhanced IGC flight log, to be downloaded and scored when
the IGC flight log is checked. I'd expect then to apply a penalty (a big
DQ?) for exceeding the energy limit and possibly a bonus for finishing
with energy usage below the limit.

It would be reasonable to put limits put on battery size and weight
(there is in F5B) and probable that the energy limit would be set well
below the maximum capacity of suitable batteries (as in F1Q and F5B).


--
Martin | martin at
Gregorie | gregorie dot org