Electrically Powered Ultralight Aircraft

Charles Vincent wrote:

cavelamb himself wrote:


Don't be snotty, Charles.


Since the subject is an electrically powered aircraft, the weight issue
is not trivial. That's been my issue with this thread from the start.

The constraints given here were to fly at the same speed and altitude
but at a higher weright.

You can increase lift via increased angle of attack only as far as
CLmax. No Farther. (You seem to have that part right)

Beyond that any increased weight will require increased wing area.

Aspect ratio alone won't answer is most cases.

And - an electric powered plane would NOT lose weight in flight.

No electrons are "consumed" - no change in battery weight.



Not really being snotty at all. Frankly, I was in the process of
deleting screenfulls of messages on the topic of electric powered
airplanes being as the subject really holds no interest for me. For
some reason I happened to read "The advantage from the electric engine
at cruise is that it uses zero energy" on one message just as I deleted
it. Pulling it back from the trash, I felt compelled to respond to it.
My mistake. For some reason you are in turn compelled to nit pick my
correct assertion because it did not completely cover the relevant
aerodynamic theory. In my opinion, it covered enough, but not following
the thread, I have no idea what sort of debate has been raging. As I
stated elsewhere, I just didn't expect that information required for
even the most basic pilot ticket would be the subject of any debate
here. In the end, to fly at the same speed and altitude but at a higher
weight requires more power be applied, whether you use that power to
drag the same wing at a higher angle of attack or a bigger wing doesn't
change that. Or you could use more power to drag the wing at a higher
speed to generate the lift you needed. All of this ignores the fact
that for internal combustion aircraft powerplants, the weight per HP
goes down as the power goes up. Last time I looked at it, the opposite
is true of electric motors. I don't think an electric assist for an IC
engine is going to be viable for aircraft in the near future.


Charles


I guess I was just over reacting to the swing wing parasol comment.

And yes, I can see your point.
Higher Cl - or bigger wing. Either will require more power.
Which was my point as well.

Yep. A lot of this thread has been - well - fanciful?


Richard