Electrically Powered Ultralight Aircraft

On Mon, 06 Aug 2007 06:33:20 -0700, Airjunkie
wrote in .com:

Eric Raymond has been at it for a long time. Check it out at
www.solar-flight.com

http://www.solar-flight.com/sslink.html

Thank you for the information. His achievement is remarkable for the
time. Imagine what he could do 17 years later with today's ~40%
efficient photovoltaic cells and light weight lithium-ion polymer
batteries:



The Boeing Company http://www.boeing.com/news/releases/index.html
Boeing Spectrolab Terrestrial Solar Cell Surpasses 40 Percent
Efficiency

ST. LOUIS, Dec. 06, 2006 -- Boeing [NYSE: BA] today announced that
Spectrolab, Inc., a wholly-owned subsidiary, has achieved a new world
record in terrestrial concentrator solar cell efficiency. Using
concentrated sunlight, Spectrolab demonstrated the ability of a
photovoltaic cell to convert 40.7 percent of the sun's energy into
electricity. The U.S. Department of Energy's National Renewable Energy
Laboratory (NREL) in Golden, Colo., verified the milestone.

"This solar cell performance is the highest efficiency level any
photovoltaic device has ever achieved," said Dr. David Lillington,
president of Spectrolab. "The terrestrial cell we have developed uses
the same technology base as our space-based cells. So, once qualified,
they can be manufactured in very high volumes with minimal impact to
production flow."

High efficiency multijunction cells have a significant advantage over
conventional silicon cells in concentrator systems because fewer solar
cells are required to achieve the same power output. This technology
will continue to dramatically reduce the cost of generating
electricity from solar energy as well as the cost of materials used in
high-power space satellites and terrestrial applications.

"These results are particularly encouraging since they were achieved
using a new class of metamorphic semiconductor materials, allowing
much greater freedom in multijunction cell design for optimal
conversion of the solar spectrum," said Dr. Richard R. King, principal
investigator of the high efficiency solar cell research and
development effort. "The excellent performance of these materials
hints at still higher efficiency in future solar cells."

Spectrolab is reducing the cost of solar cell production through
research investments and is working with several domestic and
international solar concentrator manufacturers on clean, renewable
solar energy solutions. Currently, Spectrolab's terrestrial
concentrator cells are generating power in a 33-kilowatt full-scale
concentrator system in the Australian desert. The company recently
signed multi-million dollar contracts for its high efficiency
concentrator cells and is anticipating several new contracts in the
next few months.

Development of the high-efficiency concentrator cell technology was
funded by the NREL's High Performance Photovoltaics program and
Spectrolab.

A unit of The Boeing Company, Boeing Integrated Defense Systems
http://www.boeing.com/ids/index.html is one of the world's largest
space and defense businesses. Headquartered in St. Louis, Boeing
Integrated Defense Systems is a $30.8 billion business. It provides
network-centric system solutions to its global military, government,
and commercial customers. It is a leading provider of intelligence,
surveillance and reconnaissance systems; the world's largest military
aircraft manufacturer; the world's largest satellite manufacturer; a
foremost developer of advanced concepts and technologies; a leading
provider of space-based communications; the primary systems integrator
for U.S. missile defense; NASA's largest contractor; and a global
leader in sustainment solutions and launch services.
###

I e-mailed a copy of the article below to Eric Raymond. Here is his
reply:

Larry,

Thanks for the info on Specrolab's progress. I used to be in
contact with them, but gave up because their prices were too high.
A much more interesting company is SunPower. They are making
cheap, one sun cells that are 22% efficient. I plan to use them
on my next plane, a two seater.

Eric Raymond


A two-place photovoltaic powered aircraft will be interesting. Here's
some information on SunPower:


http://www.sunpowercorp.com
http://www.sunpower.com
http://www.sunpowercorp.com/commercial/solar_cells.html
The SunPower A-300 solar cell is a 125mm, 20% (minimum) efficiency,
high-performance, single crystal silicon solar cell. The A-300 cell
offers up to 50% more power per unit area than conventional solar
cells. It is particularly unique because the metal contacts needed to
collect and conduct electricity are located on the back surface – away
from the sunlight. This design eliminates the need for reflective
metal contacts to be placed on the front of the solar cell, improving
our solar cell performance and creating a uniformly smooth, black
appearance.



================================================== =======
On Mon, 06 Aug 2007 16:01:03 GMT, Larry Dighera
wrote in :

On Mon, 06 Aug 2007 06:33:20 -0700, Airjunkie
wrote in .com:

Eric Raymond has been at it for a long time. Check it out at
www.solar-flight.com

http://www.solar-flight.com/sslink.html

Thank you for the information. His achievement is remarkable for the
time. Imagine what he could do 17 years later with today's ~40%
efficient photovoltaic cells and light weight lithium-ion polymer
batteries:



The Boeing Company http://www.boeing.com/news/releases/index.html
Boeing Spectrolab Terrestrial Solar Cell Surpasses 40 Percent
Efficiency

ST. LOUIS, Dec. 06, 2006 -- Boeing [NYSE: BA] today announced that
Spectrolab, Inc., a wholly-owned subsidiary, has achieved a new world
record in terrestrial concentrator solar cell efficiency. Using
concentrated sunlight, Spectrolab demonstrated the ability of a
photovoltaic cell to convert 40.7 percent of the sun's energy into
electricity. The U.S. Department of Energy's National Renewable Energy
Laboratory (NREL) in Golden, Colo., verified the milestone.

"This solar cell performance is the highest efficiency level any
photovoltaic device has ever achieved," said Dr. David Lillington,
president of Spectrolab. "The terrestrial cell we have developed uses
the same technology base as our space-based cells. So, once qualified,
they can be manufactured in very high volumes with minimal impact to
production flow."

High efficiency multijunction cells have a significant advantage over
conventional silicon cells in concentrator systems because fewer solar
cells are required to achieve the same power output. This technology
will continue to dramatically reduce the cost of generating
electricity from solar energy as well as the cost of materials used in
high-power space satellites and terrestrial applications.

"These results are particularly encouraging since they were achieved
using a new class of metamorphic semiconductor materials, allowing
much greater freedom in multijunction cell design for optimal
conversion of the solar spectrum," said Dr. Richard R. King, principal
investigator of the high efficiency solar cell research and
development effort. "The excellent performance of these materials
hints at still higher efficiency in future solar cells."

Spectrolab is reducing the cost of solar cell production through
research investments and is working with several domestic and
international solar concentrator manufacturers on clean, renewable
solar energy solutions. Currently, Spectrolab's terrestrial
concentrator cells are generating power in a 33-kilowatt full-scale
concentrator system in the Australian desert. The company recently
signed multi-million dollar contracts for its high efficiency
concentrator cells and is anticipating several new contracts in the
next few months.

Development of the high-efficiency concentrator cell technology was
funded by the NREL's High Performance Photovoltaics program and
Spectrolab.

A unit of The Boeing Company, Boeing Integrated Defense Systems
http://www.boeing.com/ids/index.html is one of the world's largest
space and defense businesses. Headquartered in St. Louis, Boeing
Integrated Defense Systems is a $30.8 billion business. It provides
network-centric system solutions to its global military, government,
and commercial customers. It is a leading provider of intelligence,
surveillance and reconnaissance systems; the world's largest military
aircraft manufacturer; the world's largest satellite manufacturer; a
foremost developer of advanced concepts and technologies; a leading
provider of space-based communications; the primary systems integrator
for U.S. missile defense; NASA's largest contractor; and a global
leader in sustainment solutions and launch services.
###

wrote in message
ups.com...

For a battery-powered car todays practical approach is to have a
second engine for backup or as you suggest to generate electricity.
When they start selling cars only powered by batteries I'm going to
invest in a tow truck business. For aircraft the best use for
batteries today is to start the engine. Lange has demonstrated what is
possible with today's batteries/motors and while it provides an
attractive self-launch the cost and range tradeoffs bring it back into
perspective.



I think this is a little pessimistic. Critics of the pure electric seem to
focus on the "one-car does everything" strategy where it's easier to find
faults. The "electrics don't equal engine powered cars" isn't the whole
story.

Americans, at least, seem to have developed a another strategy for dealing
with fuel prices that spike every summer. They own an old, cheap econobox
they dust off when gas prices exceed $3. They drive their SUV's only when
they need the capacity.

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.

Economically, the 2- car strategy can be implemented without owning two
cars. Just RENT the SUV when you need it. Considering total ownership
costs, this is a good deal. Looking at all the rental discounts available
to me, I don't plan to replace my SUV.

Interestingly, range alone isn't, in itself, a killer. If the battery pack
can be recharged in less than 10 minutes, the limited range is less of a
factor. The newest Lithium Phospate cells can reach 80% charge in one
minute and full charge in 5 minutes. So, if you invest in a tow truck, get
one with a diesel generator set.

Most likely, popular parking areas will be equipped with charging outlets.
I can imagine shopping centers with signs saying, "Shop here while you
recharge, FREE!" I can also imagine employers getting tax incentives to
provide their workers with access to a recharging station.

My bets are on the pure electric vehicle.

Bill Daniels

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..

wrote in message
ups.com...

For a battery-powered car todays practical approach is to have a
second engine for backup or as you suggest to generate electricity.
When they start selling cars only powered by batteries I'm going to
invest in a tow truck business. For aircraft the best use for
batteries today is to start the engine. Lange has demonstrated what is
possible with today's batteries/motors and while it provides an
attractive self-launch the cost and range tradeoffs bring it back into
perspective.



I think this is a little pessimistic. Critics of the pure electric seem
to focus on the "one-car does everything" strategy where it's easier to
find faults. The "electrics don't equal engine powered cars" isn't the
whole story.

Americans, at least, seem to have developed a another strategy for dealing
with fuel prices that spike every summer. They own an old, cheap econobox
they dust off when gas prices exceed $3. They drive their SUV's only when
they need the capacity.

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.

Economically, the 2- car strategy can be implemented without owning two
cars. Just RENT the SUV when you need it. Considering total ownership
costs, this is a good deal. Looking at all the rental discounts available
to me, I don't plan to replace my SUV.

Interestingly, range alone isn't, in itself, a killer. If the battery
pack can be recharged in less than 10 minutes, the limited range is less
of a factor. The newest Lithium Phospate cells can reach 80% charge in
one minute and full charge in 5 minutes. So, if you invest in a tow
truck, get one with a diesel generator set.

Most likely, popular parking areas will be equipped with charging outlets.
I can imagine shopping centers with signs saying, "Shop here while you
recharge, FREE!" I can also imagine employers getting tax incentives to
provide their workers with access to a recharging station.

My bets are on the pure electric vehicle.


In the early 1980's, Mother Earth News made a hybrid car that got 75 miles
per gallon. It was a Opel GT (heavy) powered by a jet engine starter motor
(inefficient) and a relatively inefficient small gas motor. The gas motor
powered the alternator which charged the batteries which ran the electric
motor. At the time, they noted that this wasn't new technology, but was the
way diesel train engines worked. In 2010, GM will introduce the Chevy Volt,
which is pretty much the same concept, which I'm convinced is the way to go.
I think this does have promise for airplanes as well. The IC engine and
batteries can be place for optimum weight distribution, and the IC engine
can be heavilly vibration isolated.

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 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

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

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?

They talk about "With your electrical company's incentive pricing
factored in, it will cost you roughly 1 cent per mile to drive the
Tesla Roadster".

Keep in mind they are targeting California.

In California, the "incentive pricing" is the more you use, the more
you pay per kWh.

There is the quote "Single-occupancy access to all carpool lanes".

Yeah, true for a while, but all the permits that are ever going to
be issued were issued long ago.

Just too much hype and inconsistancy for me.


--
Jim Pennino

Remove .spam.sux to reply.

On Mon, 06 Aug 2007 00:14:14 -0700, James Sleeman
wrote in
. 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).

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; 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, so energy demands for powering an aircraft are considerably
more demanding than those for an automobile.

That said though, I recently saw an article somewhere about an
electric car with a stirling engine tucked away in the back (Deam
Kamen was in on it somewhere - he's the Segway and fancy wheelchair
guy).

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.

On the face of it, that seems like not a bad idea for how an electric
aircraft could be realistic - take your stirling engine, hook it
through a smaller, cheaper, lighter battery system to your electric
motor. The battery would act as a buffer (capacitor) to allow for
stored energy to do rapid changes in power to the drive motor, the
stirling engine would tick away at a constant rate feeding it's
generated electricy into the battery.

But then, I'm no engineer, I'm sure it's already been discounted as
impractical by the real engineers Maybe the stirling engine ends
up so big and heavy to produce the power required that it's useless.

The comparative light weight and high energy density of lithium-ion
polymer batteries makes them a potential enabling technology for
electrically powered aircraft as well as automobiles. All-electric
automobiles are entering the marketplace finally:

Our customers are a diverse group. All value the sports car
performance of zero to 60 mph in about 4 seconds and a top speed
of more than 130 mph, but many of our customers are also concerned
about the environment. Some, such as customer Stephen Casner, have
owned (and still own) older electric vehicles like Toyota's Rav 4.
(Read his Tesla Motors blog at:
http://cts.vresp.com/c/?TeslaMotors/...4be/9291be675f

Early customers include Google Co-Founders Sergey Brin and Larry
Page, actor George Clooney, comedian Jay Leno, and California
Governor Arnold Schwarzenegger. Tesla Motors continues to take
reservations for the 2008 model year Tesla Roadster at our website
at:
http://cts.vresp.com/c/?TeslaMotors/...4be/d99894a034

Tesla Motors is closing out July with another significant
milestone reached: We have now accepted more than 560 reservations
for the Tesla Roadster toward an anticipated first year production
total of 800 cars.
http://cts.vresp.com/c/?TeslaMotors/...4be/4ed5aad61f

And if this prototype is an indication, all-electric automobiles will
no longer suffer from an image of being slow and impractical:

http://www.gizmag.com/go/6104/1/
The 640 bhp MINI QED plug-in EV
(link to this article)

Page: 1 2

September 4, 2006 Q.E.D. is an abbreviation of the Latin phrase
"quod erat demonstrandum" which means, "which was to be
demonstrated". In simple terms, it indicates that something has
been definitively proven. Accordingly, the MINI QED electric
hybrid is aptly named as it dispels any doubts about the validity
of in-hub electric motors playing their part in the future of the
automobile. PML FlightLink designs and manufacture electric
motors, EV drive systems, joystick controls and controllers and
bespoke motors for specialist applications and the MINI QED was
built to showcase their expertise in wheelmotors, with a view to
supplying what we expect will be a booming market in electric
vehicle applications over coming decades.

The result is a MINI with four times the horsepower of a Cooper S,
supercar performance and the prospects of some very serious EVs in
the near future. The QED is a ripper, using four 120kW (160bhp)
wheel motors complete with invertors to convert momentum back into
stored energy under brakes. With one on each corner you have
Ferrari-like power and very controllable independent drive on all
four wheels.

In the MINI QED, this package offers a 0-60mph time of 3.7 seconds
and a 150mph top speed – supercar territory. An on-board petrol
engined generator offers enough electrons to run continuously at
motorway speeds without depleting the battery, and you can plug it
in at night and commute in full electric mode if you wish.

As the invertor can exert more retardation than brakes, the
conventional disc brakes have been discarded altogether.

The inwheel motors and magnesium alloy wheels, and tyres, have a
total mass of 24kg. The original assembly mass on the MINI One was
22.5kg. With so little difference in unsprung mass (the brake
hubs and discs have been removed), and full regenerative braking,
the ride is claimed to be no different.

More importantly, it means dynamic management of up to 750Nm
torque at each wheel, (3000Nm total) in either direction, to
ensure optimum use of available power. The system can also use
steering (driver intent and wheel alignment) and vehicle attitude
(gyroscopic sensors read pitch, roll and yaw) as inputs to the
traction control and vehicle stability systems. Put simply, the
vehicle stability system will be the key, and it will ultimately
be the software that determines what the optimum tractive
distribution will be at each instant - how the energy stored in
the 300V 70Amp Hour (700Amp peak) Lithium Polymer battery is most
effectively distributed.

...continued: http://www.pmlflightlink.com/archive/news_mini.html

So it would appear that high-performance all-electric automobiles are
viable and in fact being produced commercially now. And while there
have been some successful electrically powered, unmanned aircraft
demonstrated, such as those of Dr. Paul MacCready's AeroVironment:

http://www.avinc.com/uav_lab_project_detail.php?id=40
Pathfinder flew to 50,567 feet at Edwards September 12, 1995, its
first trip to the stratosphere. From there, it was improved and
taken to the Pacific Missile Range Facility (PMRF), Kauai, Hawaii
for test flights in 1997, where it flew to 71,504 feet on July 7,
before performing a series of science missions over the Hawaiian
Islands.

http://www.avinc.com/uas_dev_project_detail.php?id=115
Global Observer is the latest development in High Altitude Long
Endurance (HALE) UAS, being the first operational configuration
able to provide long-dwell stratospheric capability with global
range and no latitude restrictions. Global Observer's unique
combination of both extreme flight duration and stratospheric
operating altitude is designed to deliver advantages in cost,
capacity, coverage, flexibility, and reliability that make it a
compelling complement to existing satellite, aerial and
terrestrial assets.

Missions Communications Relay & Remote Sensing
Features High-Altitude, Long-Endurance platform (all latitude
capability)
Endurance/Range Over 1 week/global
Payload Up to 400 lbs. for GO-1 & 1,000 lbs for GO-2
Operating Altitude 65,000 feet
Expected Availability Within 2 years for U.S. government, with
funding

There are also manned, commercially produced, electrically powered
sailplanes available in the marketplace:


http://www.lange-flugzeugbau.de/htm/...tares_20E.html
Antares 20E

http://lange-flugzeugbau.com/pdf/new...%20issue01.pdf
Today Lange Flugzeugbau received the EASA type certification for
the Antares 20E. (EASA TCDS No. A.092). This is the first time in
the world that an aircraft with an electrical propulsion system
receives a type certificate.
http://www.nadler.com/public/Antares.html


http://www.dg-flugzeugbau.de/elektroflieger-e.html
DG-800E the uncompromised Motor glider with Electro-Power?


Here's a little history:

http://www.solarimpulse.com/the-hist...tion-en20.html
Solar aviation began with reduced models in the 1970s, when
affordable solar cells appeared on the market. But it was not
until 1980 that the first human flights were realised. In the
United States, Paul MacCready's team developed the Gossamer
Penguin, which opened up the way for the Solar Challenger. This
aircraft, with a maximum power of 2.5 kW, succeeded in crossing
the Channel in 1981 and in quick succession covered distances of
several hundred kilometres with an endurance of several hours. In
Europe, during this time, Günter Rochelt was making his first
flights with the Solair 1 fitted with 2500 photovoltaic cells,
allowing the generation of a maximum power of 2.2kW.

In 1990, the American Eric Raymond crossed the United States with
Sunseeker in 21 stages over almost two months. The longest lap was
400 kilometres. The Sunseeker was a solar motor bike-sail plane
with a smoothness of 30 for a tare weight of 89 kg and was
equipped with solar cells of amorphous silicon.

In the middle of the 1990s, several airplanes were built to
participate in the "Berblinger" competition. The aim was to be
able to go up to an altitude of 450m with the aid of batteries and
to maintain a horizontal flight with the power of at least 500W/m2
of solar energy, which corresponds to about half of the power
emitted by the sun at midday on the equator. The prize was won in
1996 by Professeur Voit-Nitschmann's team of Stuttgart University,
with Icare 2 (25 meters wingspan with a surface of 26 m2 of solar
cells.)
http://www.solarimpulse.com/the-solar-impulse-en5.html


And here's a glimpse at the futu

http://www.boeing.com/news/releases/...70327e_pr.html
MADRID, March 27, 2007 -- In an effort to develop environmentally
progressive technologies for aerospace applications, Boeing
researchers and industry partners throughout Europe plan to
conduct experimental flight tests in 2007 of a manned airplane
powered only by a fuel cell and lightweight batteries.

The Boeing Fuel Cell Demonstrator Airplane uses a Proton Exchange
Membrane (PEM) fuel cell/lithium-ion battery hybrid system to
power an electric motor, which is coupled to a conventional
propeller. The fuel cell provides all power for the cruise phase
of flight.

During takeoff and climb, the flight segment that requires the
most power, the system draws on lightweight lithium-ion batteries.
(Boeing graphic)



Photo of Sonex e-flight electric aircraft's electric power plant:

http://www.sonexaircraft.com/news/im...light_5947.jpg


More info:
http://en.wikipedia.org/wiki/Electric_airplane

As the invertor can exert more retardation than brakes, the
conventional disc brakes have been discarded altogether.

Oh, boy. Knowing first-hand the reliability of
electrical stuff...

Dan