Electrically Powered Ultralight Aircraft

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...

On Aug 17, 2:19 pm, "Morgans" wrote:
"Phil" wrote

IF these can be made practical, they sound ideal for use in an
airplane. They are light, and they can be shaped in just about any
way to fit inside the airframe. Suppose they were integrated into the
airframe and wings such that a large percentage of the airplane
consisted of battery. It might be possible to get enough capacity
there for a practical general aviation electric plane.

I can see the headlines, now.

Plane (or car) crashes, and the car's structure electrocutes the occupants.
g
--
Jim in NC

I know you're only half serious, but yes, that would have to be
considered. That's a risk in hybrid autos as well. EMTs and
firefighters are taking special training to handle the wrecks of these
cars. And the gasoline we use for our current airplanes poses the
risk of incinerating the occupants in a crash. I am not sure that an
electric plane would actually pose more risk. I would think that the
increased reliability of the propulsion system would decrease the risk
overall. How many people are killed every year in crashes caused by
engine failures?

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?


Heating the brakes. :-)

Matt

In rec.aviation.piloting 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?

It takes more power to accelerate the car to cruise speed in a given time.

F=ma

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?

Ummm, no, quite the opposite.

The laws of physics say once an object is in motion it takes no energy
to maintain the velocity UNLESS there is some other force at work
that would cause the velocity to decrease.

Since at a constant speed, the a in F=ma is zero, the force is zero
no matter the mass.

Once at speed in a car (or airplane or rocket ship) the only energy
needed to maintain speed is that equal to any drag forces that
would otherwise slow the car down.

Have you looked at the current crop of high mileage cars?

They all have very aerodynamic profiles to get the air drag down.

--
Jim Pennino

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wrote:

The laws of physics say once an object is in motion it takes no energy
to maintain the velocity UNLESS there is some other force at work
that would cause the velocity to decrease.

Since at a constant speed, the a in F=ma is zero, the force is zero
no matter the mass.

Once at speed in a car (or airplane or rocket ship) the only energy
needed to maintain speed is that equal to any drag forces that
would otherwise slow the car down.

Have you looked at the current crop of high mileage cars?

They all have very aerodynamic profiles to get the air drag down.


They also have very narrow, hard tires. Unfortunately, the DOT has laws
against solid rubber tires or they could be made even harder.

Your analysis would be mostly correct if we were talking about trains.
I've stood beside a loaded one and watched it deform the tracks. A car
on the road is like a machine rolling across a mattress. Extra weight
pushes the tire down into the mattress and increases the drag. The
energy is going into deforming the tires and heating them. Ask any over
the road trucker what happens when you're hauling 40-tons and you don't
keep your tire pressure up. Tends to light up the night.

In rec.aviation.piloting Ernest Christley wrote:
wrote:

The laws of physics say once an object is in motion it takes no energy
to maintain the velocity UNLESS there is some other force at work
that would cause the velocity to decrease.

Since at a constant speed, the a in F=ma is zero, the force is zero
no matter the mass.

Once at speed in a car (or airplane or rocket ship) the only energy
needed to maintain speed is that equal to any drag forces that
would otherwise slow the car down.

Have you looked at the current crop of high mileage cars?

They all have very aerodynamic profiles to get the air drag down.


They also have very narrow, hard tires. Unfortunately, the DOT has laws
against solid rubber tires or they could be made even harder.

Your analysis would be mostly correct if we were talking about trains.

My analysis of what?

The biggest source of drag on a car is air followed by tires.

Of course the makers are going to put hard tires on as well as
streamline the vehicle to get mileage up.

The less drag, the less gas the vehicle uses.

What's your point?

--
Jim Pennino

Remove .spam.sux to reply.