Electrically Powered Ultralight Aircraft

wrote in message
...
In rec.aviation.piloting Gig 601XL Builder wrDOTgiaconaATsuddenlink.net
wrote:
Larry Dighera wrote:
On Mon, 06 Aug 2007 05:39:01 -0700, wrote in
. com:

When they start selling cars only powered by batteries I'm going to
invest in a tow truck business.

The time has arrived:
http://www.teslamotors.com/index.php


And a good place to base the new tow truck business is about half way
between SF and LA, because that's about how far this $100,000 car will
take
you.

Scroll to the bottom of the page.

http://www.teslamotors.com/performan..._batteries.php

Or half way between LA and Vegas.

The page leads to some "interesting" information.

If you cruise around you find claims that the energy usage is 110 Wh/km,
and recharge time of about 3.5 hours.

110 Wh/km is about 11.7 kWh for a 100 mile trip.

If the charging process is 100% efficient (not in this universe), to
recharge in 3.5 hours requires 11.7/3.5, or about 3.3 kW.

At 120 V, that's 27.5 A, which is a bit beyond the standard 15 A outlet.

At 220 V, that's about 15 A, so you better have a 220 outlet nearby.

Elsewhere they talk about recharging in 2 hours with some 70 A system.

Anyone out there got a 70 A plus safety factor outlet in their house?


Well, I just put in a dedicated 50 A receptable for charging electric cars.
Now, I just need the electric car.

"Phil" wrote in message
ps.com...


Very interesting. It doesn't mention how long it takes to charge the
batteries.

It looks like they're using an Etek motor which was increasingly common in
the superheavyweight Battlebots and Robot Wars. Real monsters. (Got
thumped by 'em a few times.) For perspective, I used four smaller
power-chair motors to propel a 250-pound machine that could pull my jeep,
but heating became a real problem. If the motor and batteries are cooled
properly they'll operate a lot longer on a charge. I don't think you'd get
two hours out of a charge, though. I used a total of 120 C-cell nicads
bundled in 6 clusters of 20 wired serial, with the clusters in parallel, and
got about 30 minutes with no additional load on the frame. That's the
equivalent of two 20-pound sealed lead acid lawnmower batteries. Also, the
runtime could drop to 5 minutes if the motors operated at full stall.

Depending on the battery types they can charge pretty fast. I can't
remember the figure but it was hours or less. What you'd need to do for a
day of flying is have one or two sets charging while you're flying.

The other factor is the discharge characteristics of the batteries; some
such as the $70 Hawker 12v SLAs will carry full charge and then crap out all
at once, whereas start at 100% and gradually decrease. Lithium Ion and
later change the metric quite a bit, but you still have to be able to
predict when and how your power will drop.

The weight for these batteries and hardware was about 40 pounds total, IIRC.

An electic motor should be more reliable than a piston engine. But I
wonder what the life span of the batteries would be.

If they're treated well and conditioned properly they should last quite
awhile, but they certainly won't last as long as a Rotax. It would be a joy
not to have an internal combustion engine roaring behind your head,
though....

Weird. Except for the ultralight itself, which I sold many years ago, I
have all of the components necessary to build a couple of these.

-c

"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.

There is a fundamental problem with attempting to power an aircraft
with batteries: The propulsion system must not only move the vehicle
forward as it would with an automobile, but it must also
simultaneously maintain the aircraft's altitude;

This is significant at low airspeeds. At higher airspeeds overcoming
wind resistance takes much more power than maintaining altitude.

unlike an automobile
that only requires a small amount of energy to overcome rolling and
wind resistance once in motion, an aircraft can't coast without losing
altitude,

It sure can, until it loses speed and stalls.

Bartek

"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

On Aug 6, 10:18 am, "Bill Daniels" bildan@comcast-dot-net wrote:
This 2-car strategy works for pure electrics (EV's) too. Survey
after
survey notes that a huge majority of drivers do less than 40 miles a day
which is easilly met with EV's. The current best range of 100 miles
provides better than a 2:1 safety margin.
Bill Daniels

The Tesla Roadster gets 200 miles per charge and takes 3.5 hours to re-
charge. It goes 0-60 in something like 3 seconds.
You ought to check out Tesla Motors website.
It's an incredible, beautiful car though overpriced. Tesla is coming
out with a more reasonably priced family-type sedan for their #2 entry
to the electric car market.

Ricky

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.

On Aug 7, 3:39 am, Larry Dighera wrote:
Are external combustion engines as efficient as internal combustion
engines? Stirling engines are great for converting waste heat to
mechanical energy, but I'm not sure how appropriate they would be for
aircraft propulsion.

In theory, I think that stirling engines are quite well suited to
aircraft, all it needs is a source of "hot" and a source of "cold",
the cold is in abundance (stick a heatsink in the wind, higher you go,
colder it gets, more power the engine can deliver, directly the
opposite of IC), the hot could be provided with any number of
combustables (and some oxygen delivery system).

I found yesterday after writing my initial post an article about
exactly this - http://www.qrmc.com/fourpartstirling.html "Why Aviation
Needs the Stirling Engine by Darryl Phillips" from 1993/1994.

Given what was said in the article, I'm kind of surprised that nobody
has come up with a working protoype actually.

"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.