Electrically Powered Ultralight Aircraft

In article . com,
James Sleeman wrote:

On Aug 6, 4:52 am, Larry Dighera wrote:
Electrically Powered Ultralight Aircraft

It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to see
them as viable in the distant future either).

Look at the problem this way: In an all-electric machine, you carry ALL
of your energy supply with you: fuel and oxidizer -- to make electricity.

With any IC engine, you carry the fuel only -- the air is free (20%
oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
each gallon of fuel.

Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
have to carry an additional 7500 lb of air.

That is a lot of weight for a 3000 lb aircraft!

In article ,
Orval Fairbairn wrote:

In article . com,
James Sleeman wrote:

On Aug 6, 4:52 am, Larry Dighera wrote:
Electrically Powered Ultralight Aircraft

It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to see
them as viable in the distant future either).

Look at the problem this way: In an all-electric machine, you carry ALL
of your energy supply with you: fuel and oxidizer -- to make electricity.

With any IC engine, you carry the fuel only -- the air is free (20%
oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
each gallon of fuel.

Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
have to carry an additional 7500 lb of air.

That is a lot of weight for a 3000 lb aircraft!

DUH! I meant 4500 lb of air! That is still a lot of weight penalty.

On Mon, 06 Aug 2007 17:57:47 GMT, Orval Fairbairn
wrote in
:

In article ,
Orval Fairbairn wrote:

Look at the problem this way: In an all-electric machine, you carry ALL
of your energy supply with you: fuel and oxidizer -- to make electricity.

With any IC engine, you carry the fuel only -- the air is free (20%
oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
each gallon of fuel.

Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
have to carry an additional 7500 lb of air.

That is a lot of weight for a 3000 lb aircraft!

DUH! I meant 4500 lb of air! That is still a lot of weight penalty.

I hadn't thought of that. I wonder if a zinc-air batter might be
lighter than a lithium-ion polymer battery. Lithium, being number
three in the periodic table of elements, is pretty light; zinc is
number 30, so it's ten times heaver. But there are other concerns
like packaging requirements that come into play.

Here's some information about zinc-air batteries:

http://en.wikipedia.org/wiki/Zinc-air_battery
Zinc-air battery

Zinc-air batteries, also called “zinc-air fuel cells,“ are
non-rechargeable electro-chemical batteries powered by the
oxidation of zinc with oxygen from the air. These batteries have
very high energy densities and are relatively inexpensive to
produce. They are used in hearing aids and in experimental
electric vehicles. They may be an important part of a future zinc
economy.

Particles of zinc are mixed with an electrolyte (usually potassium
hydroxide solution); water and oxygen from the air react at the
cathode and form hydroxyls which migrate into the zinc paste and
form zincate (Zn(OH)42-), at which point electrons are released
and travel to the cathode. The zincate decays into zinc oxide and
water is released back into the system. The water and hydroxyls
from the anode are recycled at the cathode, so the water serves
only as a catalyst. The reactions produce a maximum voltage level
of 1.65 volts, but this is reduced to 1.4–1.35 V by reducing air
flow into the cell; this is usually done for hearing aid batteries
to reduce the rate of water drying out.

The term zinc-air fuel cell usually refers to a zinc-air battery
in which zinc fuel is replenished and zinc oxide waste is removed
continuously. This is accomplished by pushing zinc electrolyte
paste or pellets into an anode chamber. Waste zinc oxide is pumped
into a waste tank or bladder inside the fuel tank, and fresh zinc
paste or pellets are taken from the fuel tank. The zinc oxide
waste is pumped out at a refueling station and sent to a recycling
plant. Alternatively, this term may refer to an electro-chemical
system in which zinc is used as a co-reactant to assist the
reformation of hydrocarbon fuels on an anode of a fuel cell.

Zinc-air batteries have properties of fuel cells as well as
batteries: the zinc is the fuel, the rate of the reaction can be
controlled by controlling the air flow, and used zinc/electrolyte
paste can be removed from the cell and replaced with fresh paste.
Research is being conducted in powering electric vehicles with
zinc-air batteries.


http://micro.magnet.fsu.edu/electrom...s/zincair.html
Zinc-air batteries produce electrochemical energy by using oxygen
straight from the air. Oxygen becomes the cathode reactant, and is
diffused directly into the battery. The air cathode uses an
aqueous alkaline electrolyte to catalytically promote the reaction
of oxygen, but is not depleted or transformed at discharge. The
cathode is compact, yet at the same time has an almost unlimited
capacity, and achieves high energy densities due to the additional
volume available for the zinc anode.

The advantages of a zinc-air battery include flat discharge
voltage, safety and environmental benefits, good shelf life, and
low cost. In addition, zinc-air batteries have high volumetric
energy density compared to most primary batteries. The
disadvantages of such batteries are that they rely on ambient
conditions, they dry out once exposed to outside air, they have
flooding potential, they have limited output, and their active
life is short. It is important to note that when zinc turns it
into zinc oxide it expands, and there must be adequate space
within the battery for this expansion. The main form of gas
transfer degradation is water vapor transfer.

Orval Fairbairn wrote:
In article ,
Orval Fairbairn wrote:

In article . com,
James Sleeman wrote:

On Aug 6, 4:52 am, Larry Dighera wrote:
Electrically Powered Ultralight Aircraft
It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to see
them as viable in the distant future either).
Look at the problem this way: In an all-electric machine, you carry ALL
of your energy supply with you: fuel and oxidizer -- to make electricity.

With any IC engine, you carry the fuel only -- the air is free (20%
oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
each gallon of fuel.

Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
have to carry an additional 7500 lb of air.

That is a lot of weight for a 3000 lb aircraft!

DUH! I meant 4500 lb of air! That is still a lot of weight penalty.


Well, to be fair Orval, you do get the 90% efficiency in an electric
motor, vs the 30% in an IC engine. You'd only have to drop 1500lb of
useful load with the electric motor.

Isn't the useful load of most light airplanes somewhere between 600 and
2000lbs?

"James Sleeman" wrote in message
ups.com...
On Aug 6, 4:52 am, Larry Dighera wrote:
Electrically Powered Ultralight Aircraft

It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to see
them as viable in the distant future either).


It depends on the demand. During the worldwide battlebots craze a few years
ago there were marked technological improvements in battery technology in
the course of about four years. I imagine hybrid vehicles are really going
to push the state of the tech. It might not be viable yet, but if there's
sufficient motivation and investment it could really happen.

That would rock. Even if the cost is the same, the reduction in sound would
be wonderful. You'd want a reserve battery for the purpose of getting you
home when your mains began to taper off, though.

-c

Gattman wrote:
"James Sleeman" wrote in message
ups.com...
On Aug 6, 4:52 am, Larry Dighera wrote:
Electrically Powered Ultralight Aircraft

It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to
see them as viable in the distant future either).


It depends on the demand. During the worldwide battlebots craze a
few years ago there were marked technological improvements in battery
technology in the course of about four years. I imagine hybrid
vehicles are really going to push the state of the tech. It might
not be viable yet, but if there's sufficient motivation and
investment it could really happen.


Come on, it's not like there isn't sufficient motivation out there now and
it isn't coming from battlebots. If anyone comes up with a battery that can
power and automobile for 4 hours at highway speeds and is affordable to
produce they will be very wealthy.

If they can make one that is as efficient as a tank of gasoline they will
shortly become very, very wealthy.

"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in message
...

Come on, it's not like there isn't sufficient motivation out there now and
it isn't coming from battlebots. If anyone comes up with a battery that
can power and automobile for 4 hours at highway speeds and is affordable
to produce they will be very wealthy.

If they can make one that is as efficient as a tank of gasoline they will
shortly become very, very wealthy.

I agree. It's on the way. Wasn't too long ago that terms like "lithium
ion" and "nickle metal hydride" were unheard of to the common consumer.

Five or six years ago your choices were Hawker Genesis-style Sealed Lead
Acid or custom-built NiCad battery arrays which is what we used. NiMH and
lithium ion weren't available or affordable but the proliferation of power
chairs, stuff like the Segway, electric scooters and so forth have really
pushed the demand for lightweigh, high performance batteries.

-c

Gattman wrote:
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in message
...

Come on, it's not like there isn't sufficient motivation out there
now and it isn't coming from battlebots. If anyone comes up with a
battery that can power and automobile for 4 hours at highway speeds
and is affordable to produce they will be very wealthy.

If they can make one that is as efficient as a tank of gasoline they
will shortly become very, very wealthy.

I agree. It's on the way. Wasn't too long ago that terms like
"lithium ion" and "nickle metal hydride" were unheard of to the
common consumer.
Five or six years ago your choices were Hawker Genesis-style Sealed
Lead Acid or custom-built NiCad battery arrays which is what we used.
NiMH and lithium ion weren't available or affordable but the
proliferation of power chairs, stuff like the Segway, electric
scooters and so forth have really pushed the demand for lightweigh,
high performance batteries.
-c

Do me a favor Gattman. What is the weight of the most effeicent battery that
could power an automobile at highway speed and how long will it do so and
how long to recharge?

Gattman wrote:

I agree. It's on the way. Wasn't too long ago that terms like "lithium
ion" and "nickle metal hydride" were unheard of to the common consumer.


It takes a lot of energy to manufacture those batteries ... and recycle
them when they are used up. You have to factor that into the equation.

These batteries have high energy per unit volume but they cost a lot
of money because it takes a lot of energy to produce them.

"Larry Dighera" wrote in message
...

Personally, I'd like to see an electrically powered parachute
(http://skyhighflying.com/homepage.html) design attempted. Surly the
lighter weight would require less power. It would seem that
lithium-ion polymer batteries are a potential enabling technology.


They might be lightweight and strong, but I think they would be far too
inefficent. All the canopies I have been around have had a very poor L/D
when compared to something like a sailplane.

I always assumed they were so popular because they were so strong, portable
and quick to set-up. But I'm thinking their fuel mileage would be very poor.