Electrically Powered Ultralight Aircraft

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

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

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


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.

Have either of you guys heard of the term "thread drift"?

Both of you are responding to the part of the thread that drifted off
to the topic of hybrid CARS and how they get good mileage.

--
Jim Pennino

Remove .spam.sux to reply.

In rec.aviation.piloting Morgans wrote:

wrote

Unless the added weight is enough to deform the tires, the increase
in rolling resistance in the total energy expediture can't be found.

Bull hockey.

Just because it is not noticeable, or measurable by the lack of sensitivity
with the instrument you are currently not using, does not mean that it does
not exist.

Perhaps you would like a rephrase:

Unless the added weight is enough to deform the tires, the increase
in rolling resistance compared to the total system energy expediture
is so small that it is negligible.

Or how about:

Unless the added weight is enough to deform the tires, the increase
in rolling resistance compared to the total system energy expediture
has about the same effect as ****ing in Lake Tahoe.

--
Jim Pennino

Remove .spam.sux to reply.

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


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.

Have either of you guys heard of the term "thread drift"?

Both of you are responding to the part of the thread that drifted off
to the topic of hybrid CARS and how they get good mileage.


Fair enough.

Charles

Morgans wrote:
wrote

Unless the added weight is enough to deform the tires, the increase
in rolling resistance in the total energy expediture can't be found.

Bull hockey.

Just because it is not noticeable, or measurable by the lack of sensitivity
with the instrument you are currently not using, does not mean that it does
not exist.

More weight on the bearings will cause more rolling resistance. That is
fact, not open to dispute. If you say it is, I want to buy the rights to
the bearings you are using, so I can patent them and make a fortune.

If a bird craps on your windshield, it is more likely to noticeably
influence your aerodynamic drag than rolling resistance.....I took Jim's
"can't be found" to mean lost in the noise. According to SAE studies,
aerodynamic drag accounts for 60% of the resistance that must be
overcome for highway cruise, with tires being 25% and driveline friction
making up the last 15%.

I suspect an electric motor and associated batteries however, are going
to deform the tires. The power companies that I work with are doing
studies on a number of electric vehicles. I have been told that they
run some interesting tires and pressures.

Charles

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

cavelamb himself wrote:



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.


Have either of you guys heard of the term "thread drift"?

Both of you are responding to the part of the thread that drifted off
to the topic of hybrid CARS and how they get good mileage.


Look again, Jim.

It seems to have drifted back on thread.

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

cavelamb himself wrote:



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.


Have either of you guys heard of the term "thread drift"?

Both of you are responding to the part of the thread that drifted off
to the topic of hybrid CARS and how they get good mileage.


Look again, Jim.

It seems to have drifted back on thread.

This is probably a historic moment.

Normally what happens when thread drift begins is that it increases
at an increasing rate such that what was originally zepplin aerodynamics
becomes the best recipe for strawberry preserves...

--
Jim Pennino

Remove .spam.sux to reply.

"Charles Vincent" wrote:

Just because it is not noticeable, or measurable by the lack of sensitivity
with the instrument you are currently not using, does not mean that it does
not exist.

More weight on the bearings will cause more rolling resistance. That is
fact, not open to dispute. If you say it is, I want to buy the rights to
the bearings you are using, so I can patent them and make a fortune.

If a bird craps on your windshield, it is more likely to noticeably
influence your aerodynamic drag than rolling resistance.....I took Jim's
"can't be found" to mean lost in the noise. According to SAE studies,
aerodynamic drag accounts for 60% of the resistance that must be overcome
for highway cruise, with tires being 25% and driveline friction making up
the last 15%.

Pardon the intrusion on this interesting discussion, but just how *does* added
weight in a car impose extra load on the powerplant besides via bearing
friction and tire deformation?

Added weight means the powerplant is doing more work to maintain the same
speed; there's no way around it, the laws of physics demand it. So where's
the extra power going?

--
Dan
T-182T at BFM

Dan Luke wrote:

"Charles Vincent" wrote:


Just because it is not noticeable, or measurable by the lack of sensitivity
with the instrument you are currently not using, does not mean that it does
not exist.

More weight on the bearings will cause more rolling resistance. That is
fact, not open to dispute. If you say it is, I want to buy the rights to
the bearings you are using, so I can patent them and make a fortune.

If a bird craps on your windshield, it is more likely to noticeably
influence your aerodynamic drag than rolling resistance.....I took Jim's
"can't be found" to mean lost in the noise. According to SAE studies,
aerodynamic drag accounts for 60% of the resistance that must be overcome
for highway cruise, with tires being 25% and driveline friction making up
the last 15%.


Pardon the intrusion on this interesting discussion, but just how *does* added
weight in a car impose extra load on the powerplant besides via bearing
friction and tire deformation?

Added weight means the powerplant is doing more work to maintain the same
speed; there's no way around it, the laws of physics demand it. So where's
the extra power going?


To accellerate...