Electrically Powered Ultralight Aircraft

cavelamb himself wrote:
wrote:

To carry more weight at the same speed and altitude takes more power,
so you have to account for the energy expended kiting you
deadweight electric takeoff system around the sky as well. Sizing
an engine for cruise has been done, if only backwards. Think JATO.
Most JATO's are actually RATO (rocket assisted takeoff). I expect
RATO would beat an electric system based on energy density and the
fact that when it is done you have reduced your weight by the fuel.
I also suspect for a given amount of thrust the rocket will be
lighter than an electric motor and associated clutches and gearing.
In my opinion, at this point in time it is just as practical for a
homebuilt as well as in not.


Well, that's true enough, but the above was about hybrid cars.



No, it's not true enough.

To carry more weight at the same speed and altitude requires more LIFT.

A higher CL - and/or more wing area.

THEN, to overcome the increased drag, THEN you need more power.

But more power by itself won't satisfy the constraints...


The original remark said "To carry more weight at the same speed and
altitude takes more power" -- which you have now taken the time to
substantiate with more detail. It never said it was the only factor,
and didn't need to, to rebut the earlier claim. I do not understand how
you arrive at it not being true. Frankly, I would expect any one
engaged in building or flying an airplane to understand those
relationships, and based on the FAA's published pilot exam questions and
other materials, it seems they agree.

Charles