Electrically Powered Ultralight Aircraft

On Tue, 07 Aug 2007 14:58:07 GMT, Larry Dighera
wrote:

If a 14 HP electric propulsion system weighing 46 lbs could be
constructed, apparently it would permit the use of PPGs by pilots up
to 180 lbs.

A PPG is a LOT more efficient than a powered parachute (PPC), but
still far less efficient than a rigid wing. Still, several electric
PPG's have been flown. The primary goal here is noise and vibration
reduction, a worthy goal when the engine is strapped to the pilot's
back.

The major problem is the weight of the batteries, still far heavier
than gasoline. Also the lithium polymer batteries used are still
quite expensive (over $10,000 for enough for a half hour flight) and
somewhat dangerous (sort them out and they can explode!)

-Dana

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There are electric winches that can launch a glider to 2000' AGL - it takes
about 1KWh. From that, I would expect that an electric tug would require
more than 5 KWh to do the same job since it is launching both the glider and
itself and must have reserve power to return for landing.

A problem for both the electric winch and this hypothetical tug is the
availability suitable power on the flight line. To recharge in a reasonable
time, you are going to need serious power service - maybe 440V 3-phase 200
amp service. That's not trivial to work with.

It's sort of like a neighbor of mine who was complaining about the price of
gas - his SUV only gets 12MPG. I suggested he think about pushing his 6000
pound truck 12 miles by hand. That would give him the proper respect for
the energy in a gallon of gasoline - and its value.

Liquid petroleum fuels are extremely energy dense. It's going to be really
hard to replace that with electricity. But maybe not impossible.

Bill Daniels


"Paul Hanson" wrote in message
...
A technology I have not seen even mentioned in this
lengthy (but very good) thread is that of carbon nonotube
enhanced ultracapacitors, which have the promise of
the energy density of the latest lithium polymers,
but almost infinite discharge cycles and can be recharged
in seconds. What would make a whole heap of sense (to
me at least), would to develop an electric tow plane
based around this technology. Quiet, efficient, hardly
affected by density altitude, quick as refueling with
avgas when charges are needed, etc. This would get
our fleet of non-powered aircraft off the ground just
fine, without angering the encroaching land developments
and such. An efficient/viable electric towplane, that's
what we need. I'm sure other developments would stem
from it too of course.
Hats off to all people/groups considering alternatives
at this point, and down with the naysayers!
Paul Hanson


At 23:24 09 August 2007, Maxwell wrote:

'Larry Dighera' wrote in message
. ..

I would think that would be close to the bare minimum.
I flew a fixed wing
hang glider on 10 HP for a while back in the 70s. A
Manta Fledgling, and
it
was very underpowered. Maybe 100 fpm climb or so.


I would guess the rigid wing would have a higher L/D
than a powered
parachute's 4:1, so it might require less power.
Does that sound
correct in your experience?

Indeed, quite a bit less from my experience. I think
my Fledge was supposed
to be around 10:1.



"Do the usual, unusually well"--Len Niemi

"Dana wrote
The major problem is the weight of the batteries, still far heavier
than gasoline. Also the lithium polymer batteries used are still
quite expensive (over $10,000 for enough for a half hour flight) and
somewhat dangerous (sort them out and they can explode!)

Damn straight! No way am I going to strap a bunch of lithium polymer
batteries to my butt.

Some of the newer Lithium iron cells, maybe, but they also cost a LOT more.

Still, electric flight, like many have said, still have a way to go.
--
Jim in NC

Bill Daniels wrote:
There are electric winches that can launch a glider to 2000' AGL - it takes
about 1KWh. From that, I would expect that an electric tug would require
more than 5 KWh to do the same job since it is launching both the glider and
itself and must have reserve power to return for landing.

A problem for both the electric winch and this hypothetical tug is the
availability suitable power on the flight line. To recharge in a reasonable
time, you are going to need serious power service - maybe 440V 3-phase 200
amp service. That's not trivial to work with.

The only electric winch I've seen specs for, the ESW2B,
http://www.startwinde.de/, solves that problem by consisting largely of
a bank of heavy duty 88 AH SLAs. These act as a buffer between the mains
supply and the winch motor, a 200 kW unit. This buffer allows continuous
launching off a (typically) 12 Kw mains supply. Stated power supply
requirement is anything between 7 and 20 kW, which probably reflects the
average launch rate throughout the day. 12kW is still around 30 amps:
not trivial, but a lot easier to deal with than 200.

Of course, its still expensive to put in buried cables to the winch
positions, but as an interim measure I should think that the winch could
be driven off a trailer mounted generator.

For example, we use five winch positions on our field, but almost all
launching is done from two of them. The fifth is almost never used. The
two most common positions and one of the 2nd tier positions could be
serviced from two power cables and it would make economic sense to
purchase a used trailer generator to cover the other two.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Morgans wrote:
"Dana wrote
The major problem is the weight of the batteries, still far heavier
than gasoline. Also the lithium polymer batteries used are still
quite expensive (over $10,000 for enough for a half hour flight) and
somewhat dangerous (sort them out and they can explode!)

Damn straight! No way am I going to strap a bunch of lithium polymer
batteries to my butt.

Some of the newer Lithium iron cells, maybe, but they also cost a LOT
more.
Still, electric flight, like many have said, still have a way to go.

And as if we need more proof of this.

TOKYO: Japan's Toyota Motor Corp. will delay by one or two years the rollout
of new high-mileage hybrids with lithium-ion batteries because of safety
concerns, reported a newspaper.

Toyota's decision was prompted by worries that the batteries could overheat,
catch fire or even explode, the Wall Street Journal on Thursday reported in
its online edition, quoting unnamed Toyota executives.

On Thu, 09 Aug 2007 23:13:55 -0400, Dana M. Hague
d(dash)m(dash)hague(at)comcast(dot)net wrote in
:

On Tue, 07 Aug 2007 14:58:07 GMT, Larry Dighera
wrote:

If a 14 HP electric propulsion system weighing 46 lbs could be
constructed, apparently it would permit the use of PPGs by pilots up
to 180 lbs.

A PPG is a LOT more efficient than a powered parachute (PPC), but
still far less efficient than a rigid wing. Still, several electric
PPG's have been flown. The primary goal here is noise and vibration
reduction, a worthy goal when the engine is strapped to the pilot's
back.

The major problem is the weight of the batteries, still far heavier
than gasoline. Also the lithium polymer batteries used are still
quite expensive (over $10,000 for enough for a half hour flight) and
somewhat dangerous (sort them out and they can explode!)

-Dana

That's interesting information. Thank you.


It sounds like you have quite a bit of experience in this area. Are
you able to provide links to any forums or web sites related to this
topic?

Are
you able to provide links to any forums or web sites related to this


Check this out: http://www.calcars.org/news-archive.html

David Johnson

On Aug 10, 5:12 pm, Dave wrote:
Are

you able to provide links to any forums or web sites related to this

Check this out:http://www.calcars.org/news-archive.html

David Johnson

Lithium Polymer batteries are widely used in RC planes, cars, etc and
are known to be potentially dangerous. Most runaway fires occur during
charging but it has also occurred to a lessor degree during discharge
and even storage. Vented charging safety bags are recommended for this
reason. There is a video on this link that shows the explosive power
of small LiPo's. Consider the size differance of these batteries to
the one hung under the trike in one of the first posts or those that
could be installed in the wings of a sailplane.
http://www.liposack.com/video.html

On Sat, 11 Aug 2007 06:59:02 -0700, wrote in
.com:


Lithium Polymer batteries are widely used in RC planes, cars, etc and
are known to be potentially dangerous. Most runaway fires occur during
charging but it has also occurred to a lessor degree during discharge
and even storage.

I would assume that the source of these Li-ion Polymer battery fires
is excessive electrical current flowing through the battery either
from too high a charging rate, too high a discharge rate, or a short
internal (as in the case of the Sony laptop cells) or external, or
being over charged. Perhaps it would be prudent to install a circuit
breaker of fuse to prevent too high a current and a timer to
disconnect a forgotten charger.

Vented charging safety bags are recommended for this
reason. There is a video on this link that shows the explosive power
of small LiPo's. Consider the size differance of these batteries to
the one hung under the trike in one of the first posts or those that
could be installed in the wings of a sailplane.
http://www.liposack.com/video.html

Thank you for the link. It is spectacular.


Here are some links relevant to the Sony Lithium laptop battery
recall:

Story: http://www.theinquirer.net/default.aspx?article=32550
http://news.com.com/Dell+takes+heat+...3-6105828.html

Video:
http://www.youtube.com/watch?v=WeWq6...lated&search=#

Explanation of cause:
http://reviews.cnet.com/4660-10165_7-6625980.html
http://www.prnewstoday.com/release.h...H05424082006-1
The recall arises because, on rare occasions, microscopic metal
particles in the recalled battery cells may come into contact with
other parts of the battery cell, leading to a short circuit within the
cell. Typically, a battery pack will simply power off when a cell
short circuit occurs. However, under certain rare conditions, an
internal short circuit may lead to cell overheating and potentially
flames. The potential for this to occur can be affected by variations
in the system configurations found in different notebook computers.

The thing that strikes me most in this thread is that so many people
just don't seem to understand...

1) weight

2) power

3) scale