Electric Motorglider Flies

[Larry Dighera]

ELECTRAFLYER FLIES TRIKE, MOTORGLIDER ON BATTERY POWER
(http://www.avweb.com/eletter/archives/avflash/1090-full.html#197632)
For the sport flyer who enjoys local fun flights and $100
hamburgers, Electraflyer's new battery-powered airplane may be
just right -- and with no fuel to burn, it can cut the cost of
that hamburger down to about 60 cents. That's how much it costs
to fully charge the lithium-polymer battery pack, says Randall
Fishman, president of the Electraflyer Corp.
(http://www.electraflyer.com/) The electric engine is mounted on
an old Monnet motorglider that Fishman built from a kit, and the
aircraft just this week earned its experimental airworthiness
certificate....


Watch the video:
http://www.youtube.com/watch?v=o_GCAy40RiE


Other electric aircraft:

http://www.youtube.com/watch?v=P8Pb_psj1A8
Sonex Electric Powered Flight, EAA AirVenture Oshkosh 2007
John Monnett



http://www.youtube.com/watch?v=WcWSI03NKo0
Eric Raymond with his Sunseeker electric powered self launching
sailplane discusses the engineering aspects of electric aircraft.


http://www.youtube.com/watch?v=RL18Oh_qSRM
Boeing's hydrogen fuel cell powered Dimona (a.k.a. Katana)
motor-glider is the first to fly in aviation history.
http://www.youtube.com/watch?v=XzeCQblYHic

[virtuPIC]

> * * *just right -- and with no fuel to burn, it can cut the cost of
> * * *that hamburger down to about 60 cents. That's how much it costs
> * * *to fully charge the lithium-polymer battery pack, says Randall

Yeah, plus the cost for a new battery after probably less than 1,000
recharges. Plus motor cost. Plus plus plus... And your hamburger will
ge cold when you arrive - if not even the restaurant has closed since
you flew that slow.

Take a small piston engine instead and get better performance at
similar or even lower total cost.

virtuPIC
--
Airspace V - international hangar flying!
http://www.airspace-v.com

[Larry Dighera]

On Mon, 14 Apr 2008 04:36:17 -0700 (PDT), virtuPIC
> wrote in
>:

>> * * *just right -- and with no fuel to burn, it can cut the cost of
>> * * *that hamburger down to about 60 cents. That's how much it costs
>> * * *to fully charge the lithium-polymer battery pack, says Randall
>
>Yeah, plus the cost for a new battery after probably less than 1,000
>recharges. Plus motor cost. Plus plus plus... And your hamburger will
>ge cold when you arrive - if not even the restaurant has closed since
>you flew that slow.
>

All valid points.

But the significance of this successful electrically powered aircraft
is that it (along with the very few others) clearly demonstrates that
electrically powered aircraft are somewhat feasible. For unlike
surface vehicles that only require power to propel them forward,
aircraft require additional power to sustain them in the air. So
successful electrically powered aircraft are significantly more
remarkable than electric cars.

The Li-ion batteries currently available on the market, while a
significant enabling technologic advancement over lead-acid batteries,
are not designed for the heavy demands of motive service. Given the
torrent of Li-ion cell advancements being announced regularly, I
foresee them becoming ever better suited to that service as time goes
on.

>Take a small piston engine instead and get better performance at
>similar or even lower total cost.

I'll bet the Model T owner said something similar about the Wright
Flyer. :-)

[Kloudy via AviationKB.com]

Larry Dighera wrote:
>
>Other electric aircraft:
>
> http://www.youtube.com/watch?v=P8Pb_psj1A8
> Sonex Electric Powered Flight, EAA AirVenture Oshkosh 2007
> John Monnett
>
> http://www.youtube.com/watch?v=WcWSI03NKo0
> Eric Raymond with his Sunseeker electric powered self launching
> sailplane discusses the engineering aspects of electric aircraft.
>
> http://www.youtube.com/watch?v=RL18Oh_qSRM
> Boeing's hydrogen fuel cell powered Dimona (a.k.a. Katana)
> motor-glider is the first to fly in aviation history.
> http://www.youtube.com/watch?v=XzeCQblYHic

http://www.lange-flugzeugbau.com/htm/english/products/antares_20e/antares_20E.html


--
Message posted via http://www.aviationkb.com

[Mike Isaksen]

"Kloudy via AviationKB.com" wrote ...
> Larry Dighera wrote:
>>
>>Other electric aircraft:
>>
>> http://www.youtube.com/watch?v=P8Pb_psj1A8
>> Sonex Electric Powered Flight, EAA AirVenture Oshkosh 2007
>> John Monnett
>>
>> http://www.youtube.com/watch?v=WcWSI03NKo0
>> Eric Raymond with his Sunseeker electric powered self launching
>> sailplane discusses the engineering aspects of electric aircraft.
>>
>> http://www.youtube.com/watch?v=RL18Oh_qSRM
>> Boeing's hydrogen fuel cell powered Dimona (a.k.a. Katana)
>> motor-glider is the first to fly in aviation history.
>>
>
> http://www.lange-flugzeugbau.com/htm/english/products/antares_20e/antares_20E.html
>

You guys are all chasing yesterday's news. I think our own (happily wacky)
Jay M is right now redesigning his Tron outfit with more batteries and
retractable e-drive prop.

Then he'll be smirking all the way to the bank, thinking whether to go
single engine D-jet or twin engine Eclipse.

http://www.youtube.com/watch?v=RsF2RUMmpqc

(Remember, he who laughs last,...)

[Andrew Sarangan]

On Apr 14, 10:11 am, Larry Dighera > wrote:
> On Mon, 14 Apr 2008 04:36:17 -0700 (PDT), virtuPIC
> > wrote in
> >:
>
> >> just right -- and with no fuel to burn, it can cut the cost of
> >> that hamburger down to about 60 cents. That's how much it costs
> >> to fully charge the lithium-polymer battery pack, says Randall
>
> >Yeah, plus the cost for a new battery after probably less than 1,000
> >recharges. Plus motor cost. Plus plus plus... And your hamburger will
> >ge cold when you arrive - if not even the restaurant has closed since
> >you flew that slow.
>
> All valid points.
>
> But the significance of this successful electrically powered aircraft
> is that it (along with the very few others) clearly demonstrates that
> electrically powered aircraft are somewhat feasible. For unlike
> surface vehicles that only require power to propel them forward,
> aircraft require additional power to sustain them in the air. So
> successful electrically powered aircraft are significantly more
> remarkable than electric cars.
>
> The Li-ion batteries currently available on the market, while a
> significant enabling technologic advancement over lead-acid batteries,
> are not designed for the heavy demands of motive service. Given the
> torrent of Li-ion cell advancements being announced regularly, I
> foresee them becoming ever better suited to that service as time goes
> on.
>
> >Take a small piston engine instead and get better performance at
> >similar or even lower total cost.
>
> I'll bet the Model T owner said something similar about the Wright
> Flyer. :-)

Boeing also recently flew a fuel cell + battery powered airplane.
http://www.avweb.com/avwebflash/news/BoeingFliesFuelCellAircraft_197531-1.html

This is a necessary step if GA is to survive past this century. The
technology is just getting started so things can only get better. With
piston engines, the good days are behind us.

[Larry Dighera]

On Mon, 14 Apr 2008 12:47:38 -0700 (PDT), Andrew Sarangan
> wrote in
>:

>
>Boeing also recently flew a fuel cell + battery powered airplane.
>http://www.avweb.com/avwebflash/news/BoeingFliesFuelCellAircraft_197531-1.html
>
>This is a necessary step if GA is to survive past this century. The
>technology is just getting started so things can only get better. With
>piston engines, the good days are behind us.

Agreed.

With the ever increasing torrent of discoveries being made in physics,
I fully expect advancements in anti-gravity (not to mention quantum
computing) to occur before the end of the century. But I'm an
optimist. Just as likely, some fool will unleash the nuclear dogs of
war, and sterilize our planet.

That said, electrical propulsion does have the potential for three to
four times the efficiency (~90%) of internal combustion engines (~20%
to 30%). Unlike petroleum, sunlight is (for all practical purposes)
not a finite resource, and no nation or region has a monopoly on it.
Imagine a solar powered photovoltaic system on the ground that quietly
electrolyzes water into its constituent parts, hydrogen and oxygen,
percolating away all day long generating the fuel to run a fuel-cell
electric generator (with its exhaust consisting of only pure water).
Photo-cell technology (Spectralab) is currently approaching 40%
efficiency, and electric motors and controllers are >=90% efficient,
so clean and quiet electric propulsion is clearly the future.

The application of electric propulsion for aviation today is in its
infancy, and only possible at all because of the technical
breakthrough provided by light Li-ion batteries enabling it. I look
for Li-Ion technology to steadily improve over time. As it is, the
individual cells used today are only approximately the size of common
AA batteries. Imagine the weight savings possible if larger cells
were produced; there would be significantly less steel jacketing
necessary. That said, it's difficult to imagine a battery with the
energy/power density of gasoline, so there will certainly be
tradeoffs.

Despite the fact that electric motors must use iron/steel in their
construction, they are significantly lighter (>50%) than their
internal combustion counterparts. But when the wiring, controls,
batteries and perhaps fuel-cells are considered, I would guess the
weight of an electrically powered aircraft would be roughly comparable
to one powered by an internal combustion engine. So, with
significantly less power/energy density than gasoline, batteries will
not provide the same range/duration until they are improved further.
But it is encouraging to see progress being made at last.

[[email protected]]

Larry Dighera > wrote:
> On Mon, 14 Apr 2008 12:47:38 -0700 (PDT), Andrew Sarangan
> > wrote in
> >:

> >
> >Boeing also recently flew a fuel cell + battery powered airplane.
> >http://www.avweb.com/avwebflash/news/BoeingFliesFuelCellAircraft_197531-1.html
> >
> >This is a necessary step if GA is to survive past this century. The
> >technology is just getting started so things can only get better. With
> >piston engines, the good days are behind us.

> Agreed.

> With the ever increasing torrent of discoveries being made in physics,
> I fully expect advancements in anti-gravity (not to mention quantum
> computing) to occur before the end of the century. But I'm an
> optimist. Just as likely, some fool will unleash the nuclear dogs of
> war, and sterilize our planet.

> That said, electrical propulsion does have the potential for three to
> four times the efficiency (~90%) of internal combustion engines (~20%
> to 30%). Unlike petroleum, sunlight is (for all practical purposes)
> not a finite resource, and no nation or region has a monopoly on it.
> Imagine a solar powered photovoltaic system on the ground that quietly
> electrolyzes water into its constituent parts, hydrogen and oxygen,
> percolating away all day long generating the fuel to run a fuel-cell
> electric generator (with its exhaust consisting of only pure water).
> Photo-cell technology (Spectralab) is currently approaching 40%
> efficiency, and electric motors and controllers are >=90% efficient,
> so clean and quiet electric propulsion is clearly the future.

> The application of electric propulsion for aviation today is in its
> infancy, and only possible at all because of the technical
> breakthrough provided by light Li-ion batteries enabling it. I look
> for Li-Ion technology to steadily improve over time. As it is, the
> individual cells used today are only approximately the size of common
> AA batteries. Imagine the weight savings possible if larger cells
> were produced; there would be significantly less steel jacketing
> necessary. That said, it's difficult to imagine a battery with the
> energy/power density of gasoline, so there will certainly be
> tradeoffs.

> Despite the fact that electric motors must use iron/steel in their
> construction, they are significantly lighter (>50%) than their
> internal combustion counterparts. But when the wiring, controls,
> batteries and perhaps fuel-cells are considered, I would guess the
> weight of an electrically powered aircraft would be roughly comparable
> to one powered by an internal combustion engine. So, with
> significantly less power/energy density than gasoline, batteries will
> not provide the same range/duration until they are improved further.
> But it is encouraging to see progress being made at last.

Not going to happen.

Energy densities

fuel MJ/kg MJ/L

JET-A 43 33
ethenol 30 24
Li-ion battery (projected) 1 2
NiMH battery .2 .4
ultracapacitor .02 .05

Regenerative fuel cell come in a bit under 2 MJ/kg.

http://en.wikipedia.org/wiki/Energy_density

Electricity is great stuff, but damn awkward to carry around.

--
Jim Pennino

Remove .spam.sux to reply.

[Larry Dighera]

On Tue, 15 Apr 2008 01:05:04 GMT, wrote in
>:

>
>> Despite the fact that electric motors must use iron/steel in their
>> construction, they are significantly lighter (>50%) than their
>> internal combustion counterparts. But when the wiring, controls,
>> batteries and perhaps fuel-cells are considered, I would guess the
>> weight of an electrically powered aircraft would be roughly comparable
>> to one powered by an internal combustion engine. So, with
>> significantly less power/energy density than gasoline, batteries will
>> not provide the same range/duration until they are improved further.
>> But it is encouraging to see progress being made at last.
>
>Not going to happen.
>

I hesitate to attempt to infer your meaning in that phrase, but if you
mean Li-ion batteries, perhaps. If you're referring to electrically
powered aircraft, they have already happened, and development is
progressing.

>Energy densities
>
>fuel MJ/kg MJ/L
>
>JET-A 43 33
>ethenol 30 24
>Li-ion battery (projected) 1 2
>NiMH battery .2 .4
>ultracapacitor .02 .05
>
>Regenerative fuel cell come in a bit under 2 MJ/kg.
>
>http://en.wikipedia.org/wiki/Energy_density
>

Thank you for the factual data. It's interesting that gasoline is
omitted:

http://hypertextbook.com/facts/2003/ArthurGolnik.shtml
Liquid Fuel MJ/litre litre/Tonne GJ/Tonne MJ/kg
Gasoline, aviation 33.0 1412 49.6 36.4


Here's a little more data on Li-ion cells:

http://en.wikipedia.org/wiki/Lithium_ion_battery
Specific energy density: 150 to 200 Wh/kg (540 to 720 kJ/kg)
Volumetric energy density: 250 to 530 Wh/l (900 to 1900 J/cm³)
Specific power density: 300 to 1500 W/kg (@ 20 seconds and 285
Wh/l)



There's a great comparison chart of energy densities here:

http://en.wikipedia.org/wiki/Energy_density


Here are a few of the entries:

Storage Type Energy Density By Mass (MJ/kg)
================================================== ================
lead acid battery 0.090.09–0.11[36]sm=n
lithium ion battery-present capability 0.230.23–0.28
lithium ion battery-predicted future capability 0.540.54–0.9sm=n
Regenerative Fuel Cell (fuel cell with internal Hydrogen reservoir
used much as a battery) 1.62
Lithium ion battery with nanowires 2.54-2.72
TNT 4.184
dry cowdung and cameldung 15.5
calcium (burned in air) 15.9
PET pop bottle plastic 23.5?23.5
ethanol 30
aluminum (burned in air) 31.0
Jet A aviation fuel 42.8
gasoline 46.9
compressed natural gas at 200 bar (2,900.8 psi) 53.6
compressed hydrogen gas at 700 bar (10,423.5054 psi) 143
Enriched uranium (3.5% U235) in light water reactor 3,456,000
nuclear fission (of U-235) (Used in nuclear power plants)
88,250,000


From the data in the chart it would appear that a best-case Lithium
ion battery with nanowires (2.54-2.72 MJ/kg) that would provide the
equivalent energy of a given amount of gasoline (46.9 MJ/kg) would
weigh 17.24 times as much as the gasoline it replaces. That doesn't
look too terribly feasible for aviation use. Oh well....

However, hydrogen gas compressed to a pressure of ~10,500 psi (143
MJ/kg) would only weigh ~1/3 as much as the equivalent gasoline energy
it replaces. If that hydrogen were used along with atmospheric oxygen
to produce electricity by a fuel-cell with a typical efficiency of
~36% <http://en.wikipedia.org/wiki/Fuel_cell#Efficiency>, and the
efficiency of the electrical motor, wiring, and controller were >90%,
and the weights of the total systems were roughly equivalent, it would
appear that there would be a close approximation of performance of
today's aircraft including waste heat, but not noxious emissions nor
noise. I'm not sure exactly how the overall efficiency would be
affected by the use of pressurized oxygen, or if both the hydrogen and
oxygen were produced by the electrolysis of water by photovoltaics.
(Now, if the compressed hydrogen were carried in a tubular wing spar,
imagine it's rigidity... </dream mode>)

Of course these rough theoretical calculations are predicated on
existing technologies, and don't consider the inevitable future
technical advancements.

Thank you for providing the catalyst that led to this insight into the
issue.


>Electricity is great stuff, but damn awkward to carry around.

So it appears.

[[email protected]]

Larry Dighera > wrote:
> On Tue, 15 Apr 2008 01:05:04 GMT, wrote in
> >:

> >
> >> Despite the fact that electric motors must use iron/steel in their
> >> construction, they are significantly lighter (>50%) than their
> >> internal combustion counterparts. But when the wiring, controls,
> >> batteries and perhaps fuel-cells are considered, I would guess the
> >> weight of an electrically powered aircraft would be roughly comparable
> >> to one powered by an internal combustion engine. So, with
> >> significantly less power/energy density than gasoline, batteries will
> >> not provide the same range/duration until they are improved further.
> >> But it is encouraging to see progress being made at last.
> >
> >Not going to happen.
> >

> I hesitate to attempt to infer your meaning in that phrase, but if you
> mean Li-ion batteries, perhaps. If you're referring to electrically
> powered aircraft, they have already happened, and development is
> progressing.

> >Energy densities
> >
> >fuel MJ/kg MJ/L
> >
> >JET-A 43 33
> >ethenol 30 24
> >Li-ion battery (projected) 1 2
> >NiMH battery .2 .4
> >ultracapacitor .02 .05
> >
> >Regenerative fuel cell come in a bit under 2 MJ/kg.
> >
> >http://en.wikipedia.org/wiki/Energy_density
> >

> Thank you for the factual data. It's interesting that gasoline is
> omitted:

As were many other things.


> http://hypertextbook.com/facts/2003/ArthurGolnik.shtml
> Liquid Fuel MJ/litre litre/Tonne GJ/Tonne MJ/kg
> Gasoline, aviation 33.0 1412 49.6 36.4


> Here's a little more data on Li-ion cells:

> http://en.wikipedia.org/wiki/Lithium_ion_battery
> Specific energy density: 150 to 200 Wh/kg (540 to 720 kJ/kg)
> Volumetric energy density: 250 to 530 Wh/l (900 to 1900 J/cm?)
> Specific power density: 300 to 1500 W/kg (@ 20 seconds and 285
> Wh/l)



> There's a great comparison chart of energy densities here:

> http://en.wikipedia.org/wiki/Energy_density

Which is where the above came from.


> Here are a few of the entries:

> Storage Type Energy Density By Mass (MJ/kg)
> ================================================== ================
> lead acid battery 0.090.09?0.11[36]sm=n
> lithium ion battery-present capability 0.230.23?0.28
> lithium ion battery-predicted future capability 0.540.54?0.9sm=n
> Regenerative Fuel Cell (fuel cell with internal Hydrogen reservoir
> used much as a battery) 1.62
> Lithium ion battery with nanowires 2.54-2.72
> TNT 4.184
> dry cowdung and cameldung 15.5
> calcium (burned in air) 15.9
> PET pop bottle plastic 23.5?23.5
> ethanol 30
> aluminum (burned in air) 31.0
> Jet A aviation fuel 42.8
> gasoline 46.9
> compressed natural gas at 200 bar (2,900.8 psi) 53.6
> compressed hydrogen gas at 700 bar (10,423.5054 psi) 143
> Enriched uranium (3.5% U235) in light water reactor 3,456,000
> nuclear fission (of U-235) (Used in nuclear power plants)
> 88,250,000


> From the data in the chart it would appear that a best-case Lithium
> ion battery with nanowires (2.54-2.72 MJ/kg) that would provide the
> equivalent energy of a given amount of gasoline (46.9 MJ/kg) would
> weigh 17.24 times as much as the gasoline it replaces. That doesn't
> look too terribly feasible for aviation use. Oh well....

Or any other vehicle.

Another limitation is that for something the size of a C-172, your
battery has to deliver around 120 kW to get off the ground and
climb to altitude.

> However, hydrogen gas compressed to a pressure of ~10,500 psi (143
> MJ/kg) would only weigh ~1/3 as much as the equivalent gasoline energy
> it replaces. If that hydrogen were used along with atmospheric oxygen
> to produce electricity by a fuel-cell with a typical efficiency of
> ~36% <http://en.wikipedia.org/wiki/Fuel_cell#Efficiency>, and the
> efficiency of the electrical motor, wiring, and controller were >90%,
> and the weights of the total systems were roughly equivalent, it would
> appear that there would be a close approximation of performance of
> today's aircraft including waste heat, but not noxious emissions nor
> noise. I'm not sure exactly how the overall efficiency would be
> affected by the use of pressurized oxygen, or if both the hydrogen and
> oxygen were produced by the electrolysis of water by photovoltaics.
> (Now, if the compressed hydrogen were carried in a tubular wing spar,
> imagine it's rigidity... </dream mode>)

You are forgetting about the enormous weight of a tank capable of
containing hydrogen at 10,500 psi as well as the problem of hydrogen
embittlement at those pressures.

The very last thing you would want to do is put it in a wing spar.

> Of course these rough theoretical calculations are predicated on
> existing technologies, and don't consider the inevitable future
> technical advancements.

Which are no better than a wish and a hope in the real world.


> Thank you for providing the catalyst that led to this insight into the
> issue.


> >Electricity is great stuff, but damn awkward to carry around.

> So it appears.

--
Jim Pennino

Remove .spam.sux to reply.

[Larry Dighera]

On Tue, 15 Apr 2008 17:45:04 GMT, wrote in
>:

>Another limitation is that for something the size of a C-172, your
>battery has to deliver around 120 kW to get off the ground and
>climb to altitude.
>

I don't see that fact as being too limiting. Why do you feel that's
an issue?


>> However, hydrogen gas compressed to a pressure of ~10,500 psi [700 bar] (143
>> MJ/kg) would only weigh ~1/3 as much as the equivalent gasoline energy
>> it replaces. If that hydrogen were used along with atmospheric oxygen
>> to produce electricity by a fuel-cell with a typical efficiency of
>> ~36% <http://en.wikipedia.org/wiki/Fuel_cell#Efficiency>, and the
>> efficiency of the electrical motor, wiring, and controller were >90%,
>> and the weights of the total systems were roughly equivalent, it would
>> appear that there would be a close approximation of performance of
>> today's aircraft including waste heat, but not noxious emissions nor
>> noise. I'm not sure exactly how the overall efficiency would be
>> affected by the use of pressurized oxygen, or if both the hydrogen and
>> oxygen were produced by the electrolysis of water by photovoltaics.
>> (Now, if the compressed hydrogen were carried in a tubular wing spar,
>> imagine it's rigidity... </dream mode>)
>
>You are forgetting about the enormous weight of a tank capable of
>containing hydrogen at 10,500 psi

Of course gasoline also requires tanks, but they are often just sealed
parts of the wing structure, so their weight isn't really significant.
I don't know the strength of carbon-fiber or Kevlar composite, but
pressure cylinders constructed of them are about 60% lighter than
comparable Al cylinders
<http://www.mhoxygen.com/images/Cylinder-dimensions.pdf>. It would
appear that carbon fiber or Kevlar composite pressure cylinders may be
strong enough to contain the high pressure.

There's a tensile strength chart here:


http://en.wikipedia.org/wiki/Tensile_strength#Typical_tensile_strengths

Material Ultimate strength (MPa) Density (g/cm³)
================================================== =========
Steel,
high strength alloy
(ASTM A514) 760 7.8
Carbon Fiber 5650 1.75


>as well as the problem of hydrogen emb[r]ittlement at those pressures.
>

From the information at the link below it's not clear if carbon
composite materials are subject to hydrogen embrittlement.

http://en.wikipedia.org/wiki/Hydrogen_embrittlement
Process
The mechanism begins with lone hydrogen atoms diffusing through
the metal. When these hydrogen atoms re-combine in minuscule voids
of the metal matrix to form hydrogen molecules, they create
pressure from inside the cavity they are in. This pressure can
increase to levels where the metal has reduced ductility and
tensile strength, up to the point where it cracks open ("Hydrogen
Induced Cracking", or HIC). High-strength and low-alloy steels,
aluminum, and titanium alloys are most susceptible. Steel with a
ultimate tensile strength of less than 1000 MPa or hardness of
less than 30 HRC are not generally considered susceptible to
hydrogen embrittlement.



However according to the articles below, hydrogen embrittlement
doesn't seem to be an issue with carbon fiber composite cylinders:

http://en.wikipedia.org/wiki/Hydrogen_tank
A Hydrogen tank (other names- cartridge or canister) is used for
hydrogen storage, most tanks are made of composite material
because of hydrogen embrittlement. Some tanks are used for fixed
storage others are exchangeable for refueling at a hydrogen
station[1].


http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b27.pdf
The 5,000 and 10,000 psi tanks developed by QUANTUM Technologies
have been validated to meet the requirements of DOT FMVSS304,
NGV2-2000 (both modified for 10,000 psi hydrogen) and draft
E.I.H.P standard. Typical safety tests completed, in order to
ensure safety and reliability in an automotive service environment
included: Burst Tests (2.35 safety margin), Fatigue, Extreme
Temperature, Hydrogen Cycling, Bonfire, Severe Drop Impact Test,
Flaw Tolerance, Acid Environment, Gunfire Penetration, Accelerated
Stress, Permeation and Material Tests.


>The very last thing you would want to do is put it in a wing spar.

Why do you believe that is true?

>
>> Of course these rough theoretical calculations are predicated on
>> existing technologies, and don't consider the inevitable future
>> technical advancements.
>
>Which are no better than a wish and a hope in the real world.
>

You've got to start somewhere, right?

[[email protected]]

Larry Dighera > wrote:
> On Tue, 15 Apr 2008 17:45:04 GMT, wrote in
> >:

> >Another limitation is that for something the size of a C-172, your
> >battery has to deliver around 120 kW to get off the ground and
> >climb to altitude.
> >

> I don't see that fact as being too limiting. Why do you feel that's
> an issue?

Big wires your battery has to deliver that much power without going
up in flames, yet be light enough to carry on an airplane.

> >> However, hydrogen gas compressed to a pressure of ~10,500 psi [700 bar] (143
> >> MJ/kg) would only weigh ~1/3 as much as the equivalent gasoline energy
> >> it replaces. If that hydrogen were used along with atmospheric oxygen
> >> to produce electricity by a fuel-cell with a typical efficiency of
> >> ~36% <http://en.wikipedia.org/wiki/Fuel_cell#Efficiency>, and the
> >> efficiency of the electrical motor, wiring, and controller were >90%,
> >> and the weights of the total systems were roughly equivalent, it would
> >> appear that there would be a close approximation of performance of
> >> today's aircraft including waste heat, but not noxious emissions nor
> >> noise. I'm not sure exactly how the overall efficiency would be
> >> affected by the use of pressurized oxygen, or if both the hydrogen and
> >> oxygen were produced by the electrolysis of water by photovoltaics.
> >> (Now, if the compressed hydrogen were carried in a tubular wing spar,
> >> imagine it's rigidity... </dream mode>)
> >
> >You are forgetting about the enormous weight of a tank capable of
> >containing hydrogen at 10,500 psi

> Of course gasoline also requires tanks, but they are often just sealed
> parts of the wing structure, so their weight isn't really significant.
> I don't know the strength of carbon-fiber or Kevlar composite, but
> pressure cylinders constructed of them are about 60% lighter than
> comparable Al cylinders
> <http://www.mhoxygen.com/images/Cylinder-dimensions.pdf>. It would
> appear that carbon fiber or Kevlar composite pressure cylinders may be
> strong enough to contain the high pressure.

> There's a tensile strength chart here:


> http://en.wikipedia.org/wiki/Tensile_strength#Typical_tensile_strengths

> Material Ultimate strength (MPa) Density (g/cm?)
> ================================================== =========
> Steel,
> high strength alloy
> (ASTM A514) 760 7.8
> Carbon Fiber 5650 1.75


> >as well as the problem of hydrogen emb[r]ittlement at those pressures.
> >

> From the information at the link below it's not clear if carbon
> composite materials are subject to hydrogen embrittlement.

> http://en.wikipedia.org/wiki/Hydrogen_embrittlement
> Process
> The mechanism begins with lone hydrogen atoms diffusing through
> the metal. When these hydrogen atoms re-combine in minuscule voids
> of the metal matrix to form hydrogen molecules, they create
> pressure from inside the cavity they are in. This pressure can
> increase to levels where the metal has reduced ductility and
> tensile strength, up to the point where it cracks open ("Hydrogen
> Induced Cracking", or HIC). High-strength and low-alloy steels,
> aluminum, and titanium alloys are most susceptible. Steel with a
> ultimate tensile strength of less than 1000 MPa or hardness of
> less than 30 HRC are not generally considered susceptible to
> hydrogen embrittlement.
>


> However according to the articles below, hydrogen embrittlement
> doesn't seem to be an issue with carbon fiber composite cylinders:

> http://en.wikipedia.org/wiki/Hydrogen_tank
> A Hydrogen tank (other names- cartridge or canister) is used for
> hydrogen storage, most tanks are made of composite material
> because of hydrogen embrittlement. Some tanks are used for fixed
> storage others are exchangeable for refueling at a hydrogen
> station[1].
>

> http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b27.pdf
> The 5,000 and 10,000 psi tanks developed by QUANTUM Technologies
> have been validated to meet the requirements of DOT FMVSS304,
> NGV2-2000 (both modified for 10,000 psi hydrogen) and draft
> E.I.H.P standard. Typical safety tests completed, in order to
> ensure safety and reliability in an automotive service environment
> included: Burst Tests (2.35 safety margin), Fatigue, Extreme
> Temperature, Hydrogen Cycling, Bonfire, Severe Drop Impact Test,
> Flaw Tolerance, Acid Environment, Gunfire Penetration, Accelerated
> Stress, Permeation and Material Tests.

And nowhere does it say anything about the actual tank weight.

> >The very last thing you would want to do is put it in a wing spar.

> Why do you believe that is true?

Hydrogen embrittlement.

> >> Of course these rough theoretical calculations are predicated on
> >> existing technologies, and don't consider the inevitable future
> >> technical advancements.
> >
> >Which are no better than a wish and a hope in the real world.
> >

> You've got to start somewhere, right?

Why?

Diesel airplanes sound like a lot better idea than electric or hydrogen
airplanes to me, plus the technology to do it exists now.

Diesel airplanes need some refinement to be generally usefull.

Electric and hydrogen airplanes need new and major basic science
breakthroughs which may not ever occur and right now are nothing
more than a pipe dream.


--
Jim Pennino

Remove .spam.sux to reply.

[Dylan Smith]

On 2008-04-15, Larry Dighera > wrote:
>>Another limitation is that for something the size of a C-172, your
>>battery has to deliver around 120 kW to get off the ground and
>>climb to altitude.
>
> I don't see that fact as being too limiting. Why do you feel that's
> an issue?

120kW, or about 160 horsepower, at any sane voltage is going to be a
tremendous amount of current. If your supply voltage to the motor was
600 volts, you'd need to deliver 200 amps. This requires a serious piece
of cable to do efficiently (i.e. without getting insanely hot). It also
needs batteries or a power source with a very low resistance to not also
get very hot. With typical high current motive applications like trains
or cars you can just add more metal to the conductors to the motors. You
have a weight issue with aircraft, though, with both the control
circuitry and the high voltage, high current wiring.

> Of course gasoline also requires tanks, but they are often just sealed
> parts of the wing structure, so their weight isn't really significant.
> I don't know the strength of carbon-fiber or Kevlar composite, but
> pressure cylinders constructed of them are about 60% lighter than
> comparable Al cylinders

It's not just the tanks - you also have to make an idiot proof fuelling
system that can be operated by the typical 17 year old line boy, but is
capable of handling *five tonnes* per square inch of pressure.

To put that into perspective, that's like two SUVs sitting on each
square inch of pipe, connector and tank. Without even considering the
energy content of the actual fuel, the potential energy of even an
inert gas at those sorts of pressure would result in very bad stuff
happening if someone got careless with the fuelling equipment.

While the engineering challenges can be solved, it's never going to be
anything remotely resembling low cost due to the enormous pressures
involved, and the safety issues with handling anything at those enormous
pressures.

--
From the sunny Isle of Man.
Yes, the Reply-To email address is valid.

[Larry Dighera]

On Wed, 16 Apr 2008 11:07:53 +0000 (UTC), Dylan Smith
> wrote in
>:

>On 2008-04-15, Larry Dighera > wrote:
>>>Another limitation is that for something the size of a C-172, your
>>>battery has to deliver around 120 kW to get off the ground and
>>>climb to altitude.
>>
>> I don't see that fact as being too limiting. Why do you feel that's
>> an issue?
>
>120kW, or about 160 horsepower, at any sane voltage is going to be a
>tremendous amount of current. If your supply voltage to the motor was
>600 volts, you'd need to deliver 200 amps. This requires a serious piece
>of cable to do efficiently (i.e. without getting insanely hot).

I would use bus bar instead of cable. Here's a chart showing the
ampacity for copper bus bar:
http://www.stormcopper.com/design/Ampacity-Quick-Chart.htm
It indicates that 1/4" X 1" copper would conduct 400 amps with a 30 °C
temperature rise.

>It also needs batteries or a power source with a very low resistance to not also
>get very hot.

Internal resistance is a serious issue, and deserves serious
consideration. The battery internal resistance is considerably better
than that of the fuel cell. From the battery specification sheet here
<http://a123systems.textdriven.com/product/pdf/1/ANR26650M1_Datasheet_MARCH_2008.pdf>
it would appear that it's not impossible (10 m0hms typical). The fuel
cell internal resistance is considerably higher, but I took that into
consideration in my previous rough calculations.

>With typical high current motive applications like trains
>or cars you can just add more metal to the conductors to the motors. You
>have a weight issue with aircraft, though, with both the control
>circuitry and the high voltage, high current wiring.

That is true. To decrease conductor weight silver might be
substituted for copper, but it would only provide about a 10%
improvement.

It seems fuel-cells have a rather high internal resistance at high
currents. That's where most of the losses will be.

>> Of course gasoline also requires tanks, but they are often just sealed
>> parts of the wing structure, so their weight isn't really significant.
>> I don't know the strength of carbon-fiber or Kevlar composite, but
>> pressure cylinders constructed of them are about 60% lighter than
>> comparable Al cylinders
>
>It's not just the tanks - you also have to make an idiot proof fuelling
>system that can be operated by the typical 17 year old line boy, but is
>capable of handling *five tonnes* per square inch of pressure.
>

It would appear that has already been done:
http://www.fuelcells.org/info/charts/h2fuelingstations.pdf
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VPB-46WMBCF-X&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b929eacf672fd1f9db1eb7fca01a8c1d
http://biz.yahoo.com/prnews/080331/lam082.html?.v=101
http://www.ieahia.org/pdfs/honda.pdf

>To put that into perspective, that's like two SUVs sitting on each
>square inch of pipe, connector and tank. Without even considering the
>energy content of the actual fuel, the potential energy of even an
>inert gas at those sorts of pressure would result in very bad stuff
>happening if someone got careless with the fuelling equipment.
>

It's currently being done, so evidently the technology exists.

>While the engineering challenges can be solved, it's never going to be
>anything remotely resembling low cost due to the enormous pressures
>involved, and the safety issues with handling anything at those enormous
>pressures.

It appears that it's currently cost effective enough to be viable in
the marketplace. Perhaps you are able to provide some information
that supports your assertion.

Thanks for your input, Dylan.

[Larry Dighera]

On Tue, 15 Apr 2008 22:35:03 GMT, wrote in
>:

>Larry Dighera > wrote:
>> On Tue, 15 Apr 2008 17:45:04 GMT, wrote in
>> >:
>
>> >Another limitation is that for something the size of a C-172, your
>> >battery has to deliver around 120 kW to get off the ground and
>> >climb to altitude.
>> >
>
>> I don't see that fact as being too limiting. Why do you feel that's
>> an issue?
>
>Big wires your battery has to deliver that much power without going
>up in flames, yet be light enough to carry on an airplane.
>

If the electric motor, controller, battery, and fuel-cell are sited in
close proximity to each other (al la Sonex), the connecting bus can be
kept reasonably short. As in IC engine powered aircraft, there is the
necessity to dump waste heat to the atmosphere. The electric motor,
controller, and Li-ion battery are quite efficient, but they do
generate considerable heat at the power level you chose as an example
(C-172; ~166 HP). Here's John Monnett describing the system:

http://www.youtube.com/watch?v=P8Pb_psj1A8
Sonex Electric Powered Flight, EAA AirVenture Oshkosh 2007
John Monnett

Of course there is always the potential for fire when dealing with
volatile or reactive fuels as we've been discussing. Engineers have
been reasonably successful in designing systems that minimize the
probability of that hazard. That would, of course, part of the
development goal.

As a "back of the envelope" hack at the practicability of an hydrogen
(/oxygen) fuel-cell powered electric aircraft employing present day
technology, I'd say it looks worth an effort if for no other reason
than to be ready to exploit future technical discoveries as they are
made.

[snip]

>> However according to the articles below, hydrogen embrittlement
>> doesn't seem to be an issue with carbon fiber composite cylinders:
>
>> http://en.wikipedia.org/wiki/Hydrogen_tank
>> A Hydrogen tank (other names- cartridge or canister) is used for
>> hydrogen storage, most tanks are made of composite material
>> because of hydrogen embrittlement. Some tanks are used for fixed
>> storage others are exchangeable for refueling at a hydrogen
>> station[1].
>>
>
>> http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b27.pdf
>> The 5,000 and 10,000 psi tanks developed by QUANTUM Technologies
>> have been validated to meet the requirements of DOT FMVSS304,
>> NGV2-2000 (both modified for 10,000 psi hydrogen) and draft
>> E.I.H.P standard. Typical safety tests completed, in order to
>> ensure safety and reliability in an automotive service environment
>> included: Burst Tests (2.35 safety margin), Fatigue, Extreme
>> Temperature, Hydrogen Cycling, Bonfire, Severe Drop Impact Test,
>> Flaw Tolerance, Acid Environment, Gunfire Penetration, Accelerated
>> Stress, Permeation and Material Tests.
>
>And nowhere does it say anything about the actual tank weight.
>

It was the best information I could find quickly. Over the course of
our discussion, I believe I've provided enough information to show
that the weight of the electrical equipment would be at least in the
same order of magnitude as that it would be replacing if not
reasonably close to equaling it, not only in weight, but power and
runtime. There will be differences to be sure.

>> >The very last thing you would want to do is put it in a wing spar.
>
>> Why do you believe that is true?
>
>Hydrogen embrittlement.
>

Not that I'm sincerely proposing it, but if spar/cylinder of a carbon
fiber composite tube could be successfully developed, it might be
feasible, as it appears the that material is not affected by hydrogen
embrittlement. At least that's what the information I found implies.
Personally, I don't see why it would be, as it would seem that
hydrogen could as easily migrate through composite as metal.

>> >> Of course these rough theoretical calculations are predicated on
>> >> existing technologies, and don't consider the inevitable future
>> >> technical advancements.
>> >
>> >Which are no better than a wish and a hope in the real world.
>> >
>
>> You've got to start somewhere, right?
>
>Why?
>

At this time in the history of civilization, with the planet's finite
petroleum reserves being pumped at ever higher volume, and the onset
of climate change, it would seem prudent to have the power to produce
a non-polluting, renewable-energy powered aircraft (in the event
anti-gravity technology doesn't become practicable <BG>) before the
use of our present fuel becomes impractical.

>Diesel airplanes sound like a lot better idea than electric or hydrogen
>airplanes to me, plus the technology to do it exists now.
>

It not only exists, you can currently purchase diesel converted
Cessnas. I'm not considering becoming involved in an electric
project, but it does look like electric may actually be achievable.

>Diesel airplanes need some refinement to be generally usefull.
>
>Electric and hydrogen airplanes need new and major basic science
>breakthroughs which may not ever occur and right now are nothing
>more than a pipe dream.

I believe Boeing's recent effort has demonstrated that electric fuel
cell aircraft motive power is achievable with current technology.
Hopefully Boeing's demonstration will provide some impetus toward
improvement and refinement.

[[email protected]]

Larry Dighera > wrote:
> On Tue, 15 Apr 2008 22:35:03 GMT, wrote in
> >:

> >Larry Dighera > wrote:
> >> On Tue, 15 Apr 2008 17:45:04 GMT, wrote in
> >> >:
> >
> >> >Another limitation is that for something the size of a C-172, your
> >> >battery has to deliver around 120 kW to get off the ground and
> >> >climb to altitude.
> >> >
> >
> >> I don't see that fact as being too limiting. Why do you feel that's
> >> an issue?
> >
> >Big wires your battery has to deliver that much power without going
> >up in flames, yet be light enough to carry on an airplane.
> >

> If the electric motor, controller, battery, and fuel-cell are sited in
> close proximity to each other (al la Sonex), the connecting bus can be
> kept reasonably short. As in IC engine powered aircraft, there is the
> necessity to dump waste heat to the atmosphere. The electric motor,
> controller, and Li-ion battery are quite efficient, but they do
> generate considerable heat at the power level you chose as an example
> (C-172; ~166 HP). Here's John Monnett describing the system:

Why in the world would you have a battery and a fuel cell, ignoring
for the moment that neither is practical for aircraft use?

Any waste heat just makes the problem worse. Neither batteries nor
fuel cells have the energy density required with 100% efficiency,
much less with energy ****ed away as heat.

The big wires have to be IN the battery. You think nano wires are
going to carry 120 kW?

> http://www.youtube.com/watch?v=P8Pb_psj1A8
> Sonex Electric Powered Flight, EAA AirVenture Oshkosh 2007
> John Monnett

> Of course there is always the potential for fire when dealing with
> volatile or reactive fuels as we've been discussing. Engineers have
> been reasonably successful in designing systems that minimize the
> probability of that hazard. That would, of course, part of the
> development goal.

> As a "back of the envelope" hack at the practicability of an hydrogen
> (/oxygen) fuel-cell powered electric aircraft employing present day
> technology, I'd say it looks worth an effort if for no other reason
> than to be ready to exploit future technical discoveries as they are
> made.

A lab toy and press release fodder, nothing else for the forseeable
future.

<snip>

> >> You've got to start somewhere, right?
> >
> >Why?
> >

> At this time in the history of civilization, with the planet's finite
> petroleum reserves being pumped at ever higher volume, and the onset
> of climate change, it would seem prudent to have the power to produce
> a non-polluting, renewable-energy powered aircraft (in the event
> anti-gravity technology doesn't become practicable <BG>) before the
> use of our present fuel becomes impractical.

Why?

It makes more sense to put the effort into producing cheap electricity
on the ground, which has a much better chance of sucess, then synthesize
engine fuel with it.


> >Diesel airplanes sound like a lot better idea than electric or hydrogen
> >airplanes to me, plus the technology to do it exists now.
> >

> It not only exists, you can currently purchase diesel converted
> Cessnas. I'm not considering becoming involved in an electric
> project, but it does look like electric may actually be achievable.

Not a chance. The electric airplane, not the diesel.

> >Diesel airplanes need some refinement to be generally usefull.
> >
> >Electric and hydrogen airplanes need new and major basic science
> >breakthroughs which may not ever occur and right now are nothing
> >more than a pipe dream.

> I believe Boeing's recent effort has demonstrated that electric fuel
> cell aircraft motive power is achievable with current technology.
> Hopefully Boeing's demonstration will provide some impetus toward
> improvement and refinement.

Well, sure, if you goal is to spend a huge pile of money to get a
motor glider up 3000 feet.

The Boeing demo was PR for military products, pure and simple.


--
Jim Pennino

Remove .spam.sux to reply.

[[email protected]]

There is an electric motorglider that has been in series production
for over a year now, with others entering the market this year. 57 HP
motor running at 190 - 288V and pulling up to 160A. The Li-ion
battery pack delivers 10,000 feet of climb before depletion. In the
absence of soaring conditions, this translates to roughly 100 miles of
range. Certainly these are not figures that meet airplane
requirements, but they do very nicely for a motorglider, and I think
they go along way toward proving the feasibility of electric powered
aircraft for certain applications.

http://lange-flugzeugbau.com/htm/english/products/antares_20e/antares_20E.html



On Apr 16, 5:07 am, Dylan Smith > wrote:
> On 2008-04-15, Larry Dighera > wrote:
>
> >>Another limitation is that for something the size of a C-172, your
> >>battery has to deliver around 120 kW to get off the ground and
> >>climb to altitude.
>
> > I don't see that fact as being too limiting. Why do you feel that's
> > an issue?
>
> 120kW, or about 160 horsepower, at any sane voltage is going to be a
> tremendous amount of current. If your supply voltage to the motor was
> 600 volts, you'd need to deliver 200 amps. This requires a serious piece
> of cable to do efficiently (i.e. without getting insanely hot). It also
> needs batteries or a power source with a very low resistance to not also
> get very hot. With typical high current motive applications like trains
> or cars you can just add more metal to the conductors to the motors. You
> have a weight issue with aircraft, though, with both the control
> circuitry and the high voltage, high current wiring.
>
> > Of course gasoline also requires tanks, but they are often just sealed
> > parts of the wing structure, so their weight isn't really significant.
> > I don't know the strength of carbon-fiber or Kevlar composite, but
> > pressure cylinders constructed of them are about 60% lighter than
> > comparable Al cylinders
>
> It's not just the tanks - you also have to make an idiot proof fuelling
> system that can be operated by the typical 17 year old line boy, but is
> capable of handling *five tonnes* per square inch of pressure.
>
> To put that into perspective, that's like two SUVs sitting on each
> square inch of pipe, connector and tank. Without even considering the
> energy content of the actual fuel, the potential energy of even an
> inert gas at those sorts of pressure would result in very bad stuff
> happening if someone got careless with the fuelling equipment.
>
> While the engineering challenges can be solved, it's never going to be
> anything remotely resembling low cost due to the enormous pressures
> involved, and the safety issues with handling anything at those enormous
> pressures.
>
> --
> From the sunny Isle of Man.
> Yes, the Reply-To email address is valid.

There