Electrically Powered Ultralight Aircraft

In rec.aviation.piloting Tim Ward wrote:

wrote in message
...

The advantage from the electric engine at cruise is that it uses zero
energy.

Snippage
--
Jim Pennino

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Tim Ward

At cruise the electric motor is turned off.

The only energy used is some slight bearing friction.

The electric motor is only turned on when more power than the gas
engine can provide is needed.

--
Jim Pennino

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wrote:
In rec.aviation.piloting Tim Ward wrote:

wrote in message
...

The advantage from the electric engine at cruise is that it uses zero
energy.

Snippage
--
Jim Pennino

Remove .spam.sux to reply.

You want to support this, somehow?

Tim Ward

At cruise the electric motor is turned off.

The only energy used is some slight bearing friction.

The electric motor is only turned on when more power than the gas
engine can provide is needed.


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.


Charles

In rec.aviation.piloting Charles Vincent wrote:
wrote:
In rec.aviation.piloting Tim Ward wrote:

wrote in message
...

The advantage from the electric engine at cruise is that it uses zero
energy.

Snippage
--
Jim Pennino

Remove .spam.sux to reply.

You want to support this, somehow?

Tim Ward

At cruise the electric motor is turned off.

The only energy used is some slight bearing friction.

The electric motor is only turned on when more power than the gas
engine can provide is needed.


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.

--
Jim Pennino

Remove .spam.sux to reply.

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...

In rec.aviation.piloting 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...

So if I add 1 pound to a 2400 pound gross aircraft loaded to 2300 pounds,
it would be impossible to cruise at the same speed and altitude without
the 1 pound unless I added wing area?

How about 50 pounds?

--
Jim Pennino

Remove .spam.sux to reply.

wrote:
In rec.aviation.piloting 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...

So if I add 1 pound to a 2400 pound gross aircraft loaded to 2300 pounds,
it would be impossible to cruise at the same speed and altitude without
the 1 pound unless I added wing area?

How about 50 pounds?


No. You can increase the angle of attack, which increases the lift ( to
a limit) and also increases the drag, which must be overcome with more
power. If your speed drops, so does the lift. If you could increase
your aspect ratio, you could get more lift at the same speed at the same
power I think. So I guess Richard is flying a swing wing texas
parasol.;') For the rest of us, we have to add power to carry more
weight at the same speed and altitude. Since most planes lose weight
while in flight in the real world, you actually have the opposite issue.

Charles

In rec.aviation.piloting Charles Vincent wrote:
wrote:
In rec.aviation.piloting 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...

So if I add 1 pound to a 2400 pound gross aircraft loaded to 2300 pounds,
it would be impossible to cruise at the same speed and altitude without
the 1 pound unless I added wing area?

How about 50 pounds?


No. You can increase the angle of attack, which increases the lift ( to
a limit) and also increases the drag, which must be overcome with more
power. If your speed drops, so does the lift. If you could increase
your aspect ratio, you could get more lift at the same speed at the same
power I think. So I guess Richard is flying a swing wing texas
parasol.;') For the rest of us, we have to add power to carry more
weight at the same speed and altitude. Since most planes lose weight
while in flight in the real world, you actually have the opposite issue.


Gee, you mean all I gotta do is tweek the trim and throttle a bit?

Who'd have guessed it? :-)


--
Jim Pennino

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Charles Vincent wrote:

No. You can increase the angle of attack, which increases the lift ( to
a limit) and also increases the drag, which must be overcome with more
power. If your speed drops, so does the lift. If you could increase
your aspect ratio, you could get more lift at the same speed at the same
power I think. So I guess Richard is flying a swing wing texas
parasol.;') For the rest of us, we have to add power to carry more
weight at the same speed and altitude. Since most planes lose weight
while in flight in the real world, you actually have the opposite issue.

Charles


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.

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

wrote:
In rec.aviation.piloting Charles Vincent wrote:
wrote:
In rec.aviation.piloting Tim Ward wrote:

wrote in message
...
The advantage from the electric engine at cruise is that it uses zero
energy.
Snippage
--
Jim Pennino

Remove .spam.sux to reply.
You want to support this, somehow?
Tim Ward
At cruise the electric motor is turned off.

The only energy used is some slight bearing friction.

The electric motor is only turned on when more power than the gas
engine can provide is needed.


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.


Well in cruise in a car, more weight does not increase your aerodynamic
drag like it does on an airplane, but it does increase your rolling
resistance in the real world, so there is no free lunch. Different
tradeoffs for different missions. I guess that is why cheetahs and
sparrows look so different.

Charles