http://www.teslamotors.com/

Larry Dighera wrote:
> http://www.teslamotors.com/

Well they say the motor weighs 70 pounds and produces 248 HP but I can't
find anything about the weight of the batteries.

On Tue, 9 Jan 2007 09:31:49 -0600, "Gig 601XL Builder"
<wrDOTgiaconaATsuddenlink.net> wrote in
>:

>Larry Dighera wrote:
>> http://www.teslamotors.com/
>
>Well they say the motor weighs 70 pounds and produces 248 HP but I can't
>find anything about the weight of the batteries.
>

Total weight is indicated as ~2,400 lbs (including air conditioning).
Given its 1:10 power to weight ratio, I'd say, if it had wings instead
of the beefy structure it requires to meet road safety standards, it
would fly. It wouldn't require any fuel. Recharges fully in 3.5
hours. I wonder if noise attenuating headsets would be necessary.

Larry Dighera > wrote:
>
> "Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote:
>>
>> Larry Dighera wrote:
>>>
>>> http://www.teslamotors.com/
>>
>> Well they say the motor weighs 70 pounds and produces 248 HP but I can't
>> find anything about the weight of the batteries.
>>
> Total weight is indicated as ~2,400 lbs (including air conditioning).
> Given its 1:10 power to weight ratio, I'd say, if it had wings instead
> of the beefy structure it requires to meet road safety standards, it
> would fly. It wouldn't require any fuel. Recharges fully in 3.5
> hours.

The batteries weigh 900 lb., and put out 75 HP for an hour. You wouldn't
get too far on that in a C150.

Recently, Larry Dighera > posted:

> http://www.teslamotors.com/
>
I even suspect that cars fitting this description beyond shape or color
are a long way off. The endurance/performance claims by this outfit are
for some reason not able to be produced by the major car companies (or
anyone else?). Why is that? I didn't see any reference to the specific
design of the motor, and if I had a lot of time on my hands, I'd do a
patent search. I'll just remain skeptical until shown more details.

Neil

On Tue, 09 Jan 2007 10:19:00 -0600, James Robinson >
wrote in >:

>Larry Dighera > wrote:
>>
>> "Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote:
>>>
>>> Larry Dighera wrote:
>>>>
>>>> http://www.teslamotors.com/
>>>
>>> Well they say the motor weighs 70 pounds and produces 248 HP but I can't
>>> find anything about the weight of the batteries.
>>>
>> Total weight is indicated as ~2,400 lbs (including air conditioning).
>> Given its 1:10 power to weight ratio, I'd say, if it had wings instead
>> of the beefy structure it requires to meet road safety standards, it
>> would fly. It wouldn't require any fuel. Recharges fully in 3.5
>> hours.
>
>The batteries weigh 900 lb., and put out 75 HP for an hour.

I didn't see those numbers on the Tesla Motors web site. Have you got
a source for that information? There is a chart here, but it is more
about marketing than engineering:
http://www.teslamotors.com/performance/performance.php

Your numbers seem to conflict to some degree with these:

http://en.wikipedia.org/wiki/Tesla_Roadster#Battery
Battery:
6,831 Lithium ion battery cells
About 450 kg
Full-charge time of three and a half hours
~56 kWh capacity

If an aircraft were covered in Spectrolab* triple-junction solar
cells, fuel would be free during the daylight, quiet, and pollution
free.

>You wouldn't get too far on that in a C150.

With a C-150 gross weight of ~1,600 lbs, it's considerably lighter
than the Tesla Roadster. But an aircraft wouldn't require many of the
car's systems such a transmission, electric windows, heavy running
gear (springs, 17" wheels and tires, disk brakes, power assist
steering, etc), and the Tesla motor weighs less than 70 lbs. What is
the weight of the Continental O-200 complete with its manifolding,
muffler, oil, and fuel?

Intuitively, an electrically powered aircraft employing Li battery
technology still seems feasible to me.


And, this fellow seems to have his finger in the pulse of the electric
propulsion issue:

http://www.wired.com/news/wiredmag/0,71414-0.html?tw=rss.index
Tesla has managed to produce an impractical and exorbitantly
expensive vehicle just as a revolutionary new battery has appeared
on the scene. The question is whether Tesla Company will screw its
initial owners by delivering the car with its obsolete lithium ion
laptop batteries (all 6831 of them), a more clumsy way of powering
an electric vehicle than I've ever seen. I really don't think big
oil is shaking in its boots at the appearance of a $90K two seater
that has a range of 250 miles and takes 4 hours to recharge.

The Tesla as it stands is obsolete if it doesn't use the new type
batteries from Altair[**]. It will be the laughingstock of the
business world if it delivers its current overly-complicated
battery system, with its computers and sensors and HVAC system.
Tesla has discovered that the best laid plans can be shattered
when the unexpected happens. Yet the new batteries have been known
about for months. Now they've been demoed in Sacramento in an SUV
and can be recharged in 8 minutes, flow 4 times the power of those
Tesla is using, operate in temperatures where Tesla's cannot and
can be recharged 15 times as many times as Tesla's. They are
intrisically safe and don't require all the computerized
paraphernalia the Tesla contains.

Now we'll find out whether the Tesla company is on the ball. As it
now is, the Tesla car isn't worth a damn with those obsolete
lithium ion batteries, which cost $20,000+ and last a paltry 4-5
years.


* http://www.spectrolab.com/prd/terres/tasc-main.htm

** http://www.marketwire.com/mw/release_html_b1?release_id=83895

http://www.b2i.us/profiles/investor/ResLibraryView.asp?BzID=546&ResLibraryID=16137&Category=856

On Tue, 09 Jan 2007 16:35:40 GMT, "Neil Gould"
> wrote in
>:

>Recently, Larry Dighera > posted:
>
>> http://www.teslamotors.com/
>>
>I even suspect that cars fitting this description beyond shape or color
>are a long way off.

Tesla Motors has apparently sold 200 of their all electric roadsters
which are scheduled for delivery late this summer. You can reserve on
for delivery next year.

>The endurance/performance claims by this outfit are
>for some reason not able to be produced by the major car companies (or
>anyone else?). Why is that?

Battery technology is advancing rapidly. However, GM, and their Volt
prototype, are so mired in corporate bureaucracy, that they can't even
turn a profit with their IC products.

>I didn't see any reference to the specific
>design of the motor, and if I had a lot of time on my hands, I'd do a
>patent search. I'll just remain skeptical until shown more details.
>
>Neil
>

I'm hopeful, but I don't blame you for being skeptical.

Electrically powered vehicles are the only hope to reduce the transfer
of wealth from the western world to the middle east, and reduce global
warming. If the US doesn't find some breakthrough technology soon,
we'll all be speaking Farsi before long. :-(

Recently, Larry Dighera > posted:

> On Tue, 09 Jan 2007 16:35:40 GMT, "Neil Gould" wrote:
>> I didn't see any reference to the specific
>> design of the motor, and if I had a lot of time on my hands, I'd do a
>> patent search. I'll just remain skeptical until shown more details.
>>
>
> I'm hopeful, but I don't blame you for being skeptical.
>
> Electrically powered vehicles are the only hope to reduce the transfer
> of wealth from the western world to the middle east, and reduce global
> warming. If the US doesn't find some breakthrough technology soon,
> we'll all be speaking Farsi before long. :-(
>
I agree with you that we need to develop alternative energy methods and
supplies. However, I am not convinced that we are as close to a practical
solution for electric-only vehicles as the promotional material on that
site suggests. If the information suggested by James Robinson is accurate,
the vehicle will not achieve its stated performance or endurance figures.
For one thing, a 75 hp/hr. battery won't deliver 200 kW for very long.

Neil

Recently, Larry Dighera > posted:

> On Tue, 09 Jan 2007 10:19:00 -0600, James Robinson >
> wrote in >:
>
>> Larry Dighera > wrote:
>>>
>>> "Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote:
>>>>
>>>> Larry Dighera wrote:
>>>>>
>>>>> http://www.teslamotors.com/
>>>>
>>>> Well they say the motor weighs 70 pounds and produces 248 HP but I
>>>> can't find anything about the weight of the batteries.
>>>>
>>> Total weight is indicated as ~2,400 lbs (including air
>>> conditioning). Given its 1:10 power to weight ratio, I'd say, if it
>>> had wings instead of the beefy structure it requires to meet road
>>> safety standards, it would fly. It wouldn't require any fuel.
>>> Recharges fully in 3.5 hours.
>>
>> The batteries weigh 900 lb., and put out 75 HP for an hour.
>
> I didn't see those numbers on the Tesla Motors web site. Have you got
> a source for that information? There is a chart here, but it is more
> about marketing than engineering:
> http://www.teslamotors.com/performance/performance.php
>
> Your numbers seem to conflict to some degree with these:
>
> http://en.wikipedia.org/wiki/Tesla_Roadster#Battery
> Battery:
> 6,831 Lithium ion battery cells
> About 450 kg
> Full-charge time of three and a half hours
> ~56 kWh capacity
>
I don't have my hp > W tables handy... if you do, how does Robinson's info
conflict, given that the weight is about right as "about 450 kg" ~= 990
lbs.

> Intuitively, an electrically powered aircraft employing Li battery
> technology still seems feasible to me.
>
The possibility isn't the question; what would it take?

> And, this fellow seems to have his finger in the pulse of the electric
> propulsion issue:
>
The reference is very interesting, yet I think this writer is off-target
in his critical focus on the Tesla. Would he pay $90k if it had the Altair
battery instead?

While the Altair battery offers some theoretical advantages over the Tesla
power pack, neither is a complete solution. The Altair battery's basic
configuration is 13v. @ 88 Ah.
http://www.altairnano.com/markets_amps.html

That isn't a very long drive in an electric-only vehicle. However, in a
hybrid there are potential advantages because it can be charged rapidly.
Unfortunately, it can also be discharged rapidly which can be a
significant hazard. In short, I'm intrigued, and I think that there may be
a future for PLI batteries. Additionally, the original Marketwire article
makes it seem that there is reason to be cautious about optimistic
predictions for this company, so perhaps the "bird in the hand" is the
best approach for Tesla, whether or not they can deliver on the
performance.

Neil

On Tue, 09 Jan 2007 18:20:07 GMT, "Neil Gould"
> wrote in
>:

>If the information suggested by James Robinson is accurate,

Assuming 746 watts / horsepower, and the Tesla Motor's ~56 kWh
capacity, Robinson's 75 Hp for one hour assertion seems accurate.

>the vehicle will not achieve its stated performance or endurance figures.

I don't know specifically to which figures you are referring, but the
Tesla roadster will probably easily meet it's acceleration figure.

>For one thing, a 75 hp/hr. battery won't deliver 200 kW for very long.

Perhaps the Tesla roadster doesn't need to develop 75 Hp during it's
entire run time, and there's the issue of regenerative braking, but
these things are not germane to electrically powered aircraft which
typically must produce 75% rated Hp continuously in cruise flight.

Unlike automobiles, aircraft not only require motive power to propel
them forward, but they are not afforded the luxury of a roadway to
support their weight, and I would presume aircraft drag is
considerably more than an automobile.

On Tue, 09 Jan 2007 14:38:16 GMT, Larry Dighera >
wrote:

>http://www.teslamotors.com/

I recall an article last year that talked about a light sport aircraft
that had been fitted with an electric motor of ~100hp and then powered
by a battery... But do not remember the important details, like
whether it had flown, and if so - the range.

I did a quick Google search but am not having luck finding it (my
search parameters only seem to find RC/Electric planes).

Anyone else remember the article?

-Nathan

On Tue, 09 Jan 2007 18:51:37 GMT, "Neil Gould"
> wrote in
>:


>While the Altair battery offers some theoretical advantages over the Tesla
>power pack, neither is a complete solution. The Altair battery's basic
>configuration is 13v. @ 88 Ah.
>http://www.altairnano.com/markets_amps.html
>
>That isn't a very long drive in an electric-only vehicle.

So add more cells.

>However, in a
>hybrid there are potential advantages because it can be charged rapidly.

Charge time for the Altair batteries is only a few minutes as I
recall.

Recently, Larry Dighera > posted:

> On Tue, 09 Jan 2007 18:20:07 GMT, "Neil Gould"
> > wrote in
> >:
>
>> If the information suggested by James Robinson is accurate,
>
> Assuming 746 watts / horsepower, and the Tesla Motor's ~56 kWh
> capacity, Robinson's 75 Hp for one hour assertion seems accurate.
>
>> the vehicle will not achieve its stated performance or endurance
>> figures.
>
> I don't know specifically to which figures you are referring, but the
> Tesla roadster will probably easily meet it's acceleration figure.
>
>> For one thing, a 75 hp/hr. battery won't deliver 200 kW for very
>> long.
>
> Perhaps the Tesla roadster doesn't need to develop 75 Hp during it's
> entire run time, and there's the issue of regenerative braking,
>
I imagine that the average power consumption can exceed 75 hp/hr in
typical city driving, and unless the Altair battery is used, regenerative
braking won't provide much of a recovery.

> but
> these things are not germane to electrically powered aircraft which
> typically must produce 75% rated Hp continuously in cruise flight.
>
True. I think there may be some solutions in the future, but I'm skeptical
that the Tesla motor is that solution.

> Unlike automobiles, aircraft not only require motive power to propel
> them forward, but they are not afforded the luxury of a roadway to
> support their weight, and I would presume aircraft drag is
> considerably more than an automobile.
>
I think aerodynamic drag is greater in an automobile than an airplane, but
much more of the auto motor's energy can be used for overcoming that drag
since it doesn't have to provide the energy for lift.

Neil

Larry Dighera wrote:

> Electrically powered vehicles are the only hope to reduce the transfer
> of wealth from the western world to the middle east,

Electric cars will never eliminate our dependence on oil from the middle
east. That is a bold statement and I could be wrong but I believe the
only way to eliminate our dependence on foreign oil, is to use every
possible alternative to power cars and trucks, including bio diesel,
methanol (from something other than corn), natural gas, maybe hydrogen,
and to what I believe will be a limited extent battery power. At the
same time we should stop using fuels to generate electricity that work
well in vehicles so as to save it for vehicles and use nuclear, coal
(which can be made clean with the byproduct useful for making concrete
stronger), hydro-electric, wind and solar (and I don't mean PV cells).

What I can't understand is why solar heat for your house isn't being
pushed more. Unlike solar electric cells, solar heat can easily and
quickly pay for it's self. In many parts of the country it can provide
over 90% of your heating needs. The only disadvantage I can see, is for
it to be most cost effective, you need to have it built into the house
from the start. It's hard to add it to existing homes and have it be
efficient unless certain things just happen to be right. That may be
part of why it isn't talked about more.


--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,
learn more at http://www.defectivebydesign.org/what_is_drm"

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
One stop wish list for any gift,
from anywhere, for any occasion!
http://thewishzone.com

"Larry Dighera" > wrote in message
...
> http://www.teslamotors.com/

There is already a very functional self launching sailplane, with
retractable motor, in production in Europe, as I recall. I remember it from
one of the groups several months back, but can't for the life of me remember
the name, and don't have time to search for it, right now. I was impressed.
--
Jim in NC

"Larry Dighera" > wrote

> Electrically powered vehicles are the only hope to reduce the transfer
> of wealth from the western world to the middle east, and reduce global
> warming. If the US doesn't find some breakthrough technology soon,
> we'll all be speaking Farsi before long. :-(

How do you figure that?

What do you suppose generates the majority of the electricity to recharge
that car? Fossil fuels. Until we start building nuke plants, or find a
breakthrough in solar power generation, we will be stuck with the oil and
gas noose around our necks.
--
Jim in NC

Larry Dighera wrote:
> http://www.teslamotors.com/

The real issue is probably the lack of a big enough market for such
innovations in the GA sector. Aviation in general is a very hard
business to make money in and even giants like Boeing and Airbus seem
to be never too far from slippery ground.

"Neil Gould" > wrote in message
t...
> Recently, Larry Dighera > posted:
>
>> On Tue, 09 Jan 2007 10:19:00 -0600, James Robinson >
>> wrote in >:
>>
>>> Larry Dighera > wrote:
>>>>
>>>> "Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote:
>>>>>
>>>>> Larry Dighera wrote:
>>>>>>
>>>>>> http://www.teslamotors.com/
>>>>>
>>>>> Well they say the motor weighs 70 pounds and produces 248 HP but I
>>>>> can't find anything about the weight of the batteries.
>>>>>
>>>> Total weight is indicated as ~2,400 lbs (including air
>>>> conditioning). Given its 1:10 power to weight ratio, I'd say, if it
>>>> had wings instead of the beefy structure it requires to meet road
>>>> safety standards, it would fly. It wouldn't require any fuel.
>>>> Recharges fully in 3.5 hours.
>>>
>>> The batteries weigh 900 lb., and put out 75 HP for an hour.
>>
>> I didn't see those numbers on the Tesla Motors web site. Have you got
>> a source for that information? There is a chart here, but it is more
>> about marketing than engineering:
>> http://www.teslamotors.com/performance/performance.php
>>
>> Your numbers seem to conflict to some degree with these:
>>
>> http://en.wikipedia.org/wiki/Tesla_Roadster#Battery
>> Battery:
>> 6,831 Lithium ion battery cells
>> About 450 kg
>> Full-charge time of three and a half hours
>> ~56 kWh capacity
>>
> I don't have my hp > W tables handy... if you do, how does Robinson's info
> conflict, given that the weight is about right as "about 450 kg" ~= 990
> lbs.
>

56kW is 73hp. I think the 75 hp for an hour is very close. Not enough for
an airplane in my opinion.

Danny Deger

snip

"Morgans" > wrote in message
...
>
> "Larry Dighera" > wrote
>
>> Electrically powered vehicles are the only hope to reduce the transfer
>> of wealth from the western world to the middle east, and reduce global
>> warming. If the US doesn't find some breakthrough technology soon,
>> we'll all be speaking Farsi before long. :-(
>
> How do you figure that?
>
> What do you suppose generates the majority of the electricity to recharge
> that car? Fossil fuels. Until we start building nuke plants, or find a
> breakthrough in solar power generation, we will be stuck with the oil and
> gas noose around our necks.
> --

Don't forget coal.

Danny Deger

On Tue, 9 Jan 2007 18:14:15 -0500, "Morgans"
> wrote in >:

>
>"Larry Dighera" > wrote in message
...
>> http://www.teslamotors.com/
>
>There is already a very functional self launching sailplane, with
>retractable motor, in production in Europe, as I recall. I remember it from
>one of the groups several months back, but can't for the life of me remember
>the name, and don't have time to search for it, right now. I was impressed.

Me too. The Antares was a long time in development, but it's now
certified:
http://www.lange-flugzeugbau.de/htm/english/products/antares_20e/antares_20E.html

> http://www.teslamotors.com/

Theres no soul to me in that, its batteries that make it go... theres
no mechanical engineering there (don't take that too literally), but in
an IC engine there's movement theres combustion, there's things
spinning about, in this electric motor things just are.

The brilliance of it, the raw humanity behind it isn't there anymore...
it's just a high tech toy.

On Tue, 9 Jan 2007 18:12:31 -0600, "Danny Deger"
> wrote in
>:

>I think the 75 hp for an hour is very close. Not enough for
>an airplane in my opinion.
>

How much horsepower does a Cessna 150 equipped with a Continental
O-200 power plant develop at 75% cruise power?

Take a look at the chart here
<http://www.teslamotors.com/performance/performance.php>, and notice
that at ~8,000 RPM the Tesla electric motor will develop nearly 200
Hp. Now what's your opinion?

On 9 Jan 2007 17:14:14 -0800, "
> wrote in
. com>:

>> http://www.teslamotors.com/
>
>Theres no soul to me in that, its batteries that make it go...

It's true, that petroleum was once alive (I'll leave the soul aspect
to those who have been inculcated to need religiosity), but lithium
batteries are the child of man's genius none the less.

>theres no mechanical engineering there (don't take that too literally), but in
>an IC engine there's movement theres combustion, there's things
>spinning about,

According to information at the link above, there are about 100
"things" moving. That's one hundred times more opportunity for an
internal combustion engine part to fail in flight. Or don't you find
that fact significant?

> in this electric motor things just are.

Right. One moving part, the rotor.

>The brilliance of it, the raw humanity behind it isn't there anymore...
>it's just a high tech toy.

The romance is a subjective point of view. If one is a machinist,
s/he probably shares your view. If one is an electrician or EE, s/he
sees the beauty of simplicity and efficiency.

But I understand what you mean. It's like comparing a player piano to
an electronic keyboard. Something is lost to progress.

"Larry Dighera" > wrote in message
...
> On Tue, 09 Jan 2007 18:20:07 GMT, "Neil Gould"
<...>
> Perhaps the Tesla roadster doesn't need to develop 75 Hp during it's
> entire run time, and there's the issue of regenerative braking, but
> these things are not germane to electrically powered aircraft which
> typically must produce 75% rated Hp continuously in cruise flight.
>
> Unlike automobiles, aircraft not only require motive power to propel
> them forward, but they are not afforded the luxury of a roadway to
> support their weight, and I would presume aircraft drag is
> considerably more than an automobile.
>

That's probably not a good assumption.

From http://www.t18.net/resources/T-18%20orig%20hdbk.doc page 34

An O-290 Powered T-18 can get 20+ miles per gallon at 170+ mph true air
speed

Not many gasoline powered cars can match this.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Actually, aircraft (specifically motor gliders) are far ahead!

See: http://www.nadler.com/public/Antares.html


It might take a little while before the power efficiency of batteries
equals the needs of a useful airplane...


Kirk
66

Larry Dighera > wrote:
> If an aircraft were covered in Spectrolab* triple-junction solar
> cells, fuel would be free during the daylight, quiet, and pollution
> free.

You get something like 1 kW/m^2 of energy from the sun under good
conditions, like being on the equator on a clear day in the summer. I
think current PV cells are somewhere around 10% to 15% efficient, so
that's 100-150 watts per square meter. Google says a Cessna 182 has
about 16.2 m^2 of wing area, so you might get around 1.6-2.4 kW from
solar cells covering the wings. You'd get a little more from the rest
of the skin, but IMHO probably not more than 50% additional, or 2.4
to 3.6 kW. That's 3.2 to 4.8 hp that the cells are contributing.

Also, does the solar cell factory run on solar cells?

> What is the weight of the Continental O-200 complete with its
> manifolding, muffler, oil, and fuel?

http://en.wikipedia.org/wiki/Continental_O-200 says about 170 lbs (77
kg) dry for just the engine.

For an electric drive, in addition to the weight of the motor and
batteries, you'll also need to figure in the weight of the inverter
that changes DC into three-phase AC. Some of these inverters are
air-cooled and some are liquid-cooled.

> http://www.wired.com/news/wiredmag/0,71414-0.html?tw=rss.index
> Tesla has managed to produce an impractical and exorbitantly
> expensive vehicle just as a revolutionary new battery has appeared
> on the scene.

I've only been involved in hybrid cars for about six years, but I've
already seen a few "revolutionary new batteries" come and go. Many of
these batteries turn out to be quite good at ensuring a steady flow of
press releases out and money in, but never quite manage to push any
actual electrons.

Matt Roberds

> According to information at the link above, there are about 100
> "things" moving. That's one hundred times more opportunity for an
> internal combustion engine part to fail in flight. Or don't you find
> that fact significant?

Thats the brilliance of it... theres hundreds of moving parts, it's by
no means efficient or refined, yet there are more incidents and
accidents cause by the failure of natures most sofisticated creature at
piloting the plane than there are incidents and accidents caused by the
brute under the cowling.

> According to information at the link above, there are about 100
> "things" moving. That's one hundred times more opportunity for an
> internal combustion engine part to fail in flight. Or don't you find
> that fact significant?

I don't think my last post went through correctly so here it goes
again...

The brilliance of those hundreds of moving parts that fail is just in
the fact that they hardly ever do... pilots and humans, some of the
most sophisticated animals nature has created fail more often than
engines do, the simplicity of the electric motor won't get rid of those
accidents.

Larry Dighera > wrote:

> On Tue, 09 Jan 2007 10:19:00 -0600, James Robinson >
> wrote in >:
>
>>Larry Dighera > wrote:
>>>
>>> "Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote:
>>>>
>>>> Larry Dighera wrote:
>>>>>
>>>>> http://www.teslamotors.com/
>>>>
>>>> Well they say the motor weighs 70 pounds and produces 248 HP but I
>>>> can't find anything about the weight of the batteries.
>>>>
>>> Total weight is indicated as ~2,400 lbs (including air
>>> conditioning). Given its 1:10 power to weight ratio, I'd say, if it
>>> had wings instead of the beefy structure it requires to meet road
>>> safety standards, it would fly. It wouldn't require any fuel.
>>> Recharges fully in 3.5 hours.
>>
>>The batteries weigh 900 lb., and put out 75 HP for an hour.
>
> I didn't see those numbers on the Tesla Motors web site. Have you got
> a source for that information? There is a chart here, but it is more
> about marketing than engineering:
> http://www.teslamotors.com/performance/performance.php
>
> Your numbers seem to conflict to some degree with these:
>
> http://en.wikipedia.org/wiki/Tesla_Roadster#Battery
> Battery:
> 6,831 Lithium ion battery cells
> About 450 kg
> Full-charge time of three and a half hours
> ~56 kWh capacity

The conversion factor for kg to lb is 2.205, so 450 kg is 992.25 lb.
Therefore, it's actually closer to 1,000 lb. of batteries, according to
those specs.

The conversion factor for kWh to HP-hr is 1.34, so 56 kWh is the
equivalent of 75.04 HP-hr

Here is the page on the Tesla Motors web site that I found the comment
that the batteries weighed 900 lb.

http://www.teslamotors.com/blog1/index.php?p=39&js_enabled=1

I found the 56 kWh number on another page, and simply converted it to
horsepower, since those are the units that most GA pilots would be
familiar with.

>> You wouldn't get too far on that in a C150.
>
> With a C-150 gross weight of ~1,600 lbs, it's considerably lighter
> than the Tesla Roadster. But an aircraft wouldn't require many of the
> car's systems such a transmission, electric windows, heavy running
> gear (springs, 17" wheels and tires, disk brakes, power assist
> steering, etc), and the Tesla motor weighs less than 70 lbs. What is
> the weight of the Continental O-200 complete with its manifolding,
> muffler, oil, and fuel?

Well, let's look at some numbers. A gasoline aero engine of that size is
typically about 2 lb. per HP, so a 100 HP engine would weigh about 200
lb. I believe the O-235 is listed at 215 lb., with supplies, so it's in
the ballpark.

In comparison, three phase motors typically weigh about 1 lb. per
horsepower. That would mean a 100 hp motor would weigh about 100 lb. I
suspect that the Tesla's motor weighs less, because it is rated for less
continuous duty than would be necessary on an aircraft. An automobile
engine practically loafs along when on the highway at constant speed, and
only needs to have power for short bursts of speed. An aircraft engine,
on the other hand, operates at high power for hours on end.

The fuel and tanks would also be unnecessary with an electrically-powered
aircraft. A typical C-150 has something like a 26 gallon capacity. At 6
lb. per gallon, that would be 136 lb. Add roughly 20 percent to that to
account for the weight of the tanks, or 27 lb, for a total of about 165
lb. for the fuel plus the tanks. The grand total being 215 + 165 = 380
lb. Some additional amount could be added for fuel lines, filters and
pumps, but they would be relatively small. As a round number, lets say
everything weighs 400 lb.

So, if we take out the IC engine, and replace it with the batteries used
in the Tesla, and an appropriate electric motor, we would take out 400
lb., and add 900 plus 100 lb. for the batteries and motor, assuming the
ligher weight, plus some additional for the electrical control system an
wiring. Even without the control system, we would have a net gain in
weight of about 600 lb. Considering that a C150 has a usable capacity of
only 370 lb. or so with full fuel, The electically-powered aircraft would
already be more than 200 lb. overloaded, and we haven't even considered
the pilot, passenger, or baggage. Doesn't sound too practical, does it?

Larry Dighera > wrote:

> Electrically powered vehicles are the only hope to reduce the transfer
> of wealth from the western world to the middle east, and reduce global
> warming. If the US doesn't find some breakthrough technology soon,
> we'll all be speaking Farsi before long. :-(

There are alternatives that are perfectly practical, and technically
feasible. They just aren't economic, or any better environmentally.

One of the closest is the liquafaction of coal. We have vast supplies in
North America, and it is a relatively straight-forward process to convert
it to liquid fuel. (see the Fischer-Tropsch process) The Germans and South
Africans used synfuels made from coal when they couldn't get cheaper
petroleum products. They worked well.

There are a number of environmental issues, but the biggest problem is that
fuel produced from coal is somewhat more expensive than petroleum based
fuels, and few will pay extra for them. OPEC knows how much synfuels are
to make, and they carefully keep the price of crude below those costs, so
there is little risk of a competitive supply.

Larry Dighera > wrote:

> "Danny Deger" > wrote:
>
>> I think the 75 hp for an hour is very close. Not enough for
>> an airplane in my opinion.
>>
> How much horsepower does a Cessna 150 equipped with a Continental
> O-200 power plant develop at 75% cruise power?
>
> Take a look at the chart here
> <http://www.teslamotors.com/performance/performance.php>, and notice
> that at ~8,000 RPM the Tesla electric motor will develop nearly 200
> Hp. Now what's your opinion?

The issue is not the maximum horsepower that the engine can produce, but
the capacity of the batteries. 75 HP-hr means that the batteries can
supply 75 HP for a period of one hour, under ideal conditions. If the
motor drew 150 HP, then the batteries could only supply power for 30
minutes.

Consider that a Cessna 150 can fly for perhaps 3 hours, at 75% power. To
get the equivalent range with batteries would require about 3,000 lb. of
batteries, which would be totally impractical for an aircraft that now
grosses at 1,600 lb.

On Tue, 09 Jan 2007 16:13:39 -0600, Chris W > wrote in
>:

>Larry Dighera wrote:
>
>> Electrically powered vehicles are the only hope to reduce the transfer
>> of wealth from the western world to the middle east,
>
>Electric cars will never eliminate our dependence on oil from the middle
>east. That is a bold statement and I could be wrong

In the short term, there is no question your statement is true, IMO.
In the long term, the US will need to develop many alternate power
technologies to remain independent.

>but I believe the
>only way to eliminate our dependence on foreign oil, is to use every
>possible alternative to power cars and trucks, including bio diesel,

Vegetable oil seems like a great renewable alternative fuel to me. The
question is, is there enough agricultural land to grow the amount
necessary.

>methanol (from something other than corn),

To my thinking, methanol is never going to be a significant source of
energy due to its low energy density and high energy demands for
manufacture. Its in vogue now due to farm lobby interests, IMO.

>natural gas,

There is an enormous amount of natural gas frozen under the seas.
We'll have to learn how to harvest it, but there is little doubt it
will become a prime fuel source in the future, IMO.
http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html

>maybe hydrogen,

As a storage medium for photovoltaic solar energy, hydrogen and
oxygen, the natural products of the disassociation of water, can be
"burned" directly in fuel cells. But that technology is still in its
infancy from what I've read. Here's what Honda has in mind:
http://world.honda.com/FuelCell/HomeEnergyStation/
This sort of equipment is making fuel whenever the sun is shining.

>and to what I believe will be a limited extent battery power. At the
>same time we should stop using fuels to generate electricity that work
>well in vehicles so as to save it for vehicles and use nuclear,

Nuclear has shown itself to be problematic:


http://environment.newscientist.com/channel/earth/dn10393-chernobyl-haunts-the-norwegian-uplands.html
Chernobyl haunts the Norwegian uplands
12:00 28 October 2006

Tougher controls on the slaughter of sheep have been imposed in
Norway after they were found to be contaminated with unusually
high levels of radioactivity from the Chernobyl disaster in 1986.

The Norwegian Radiation Protection Authority (NRPA) says the
problem has arisen because the sheep have feasted on an unusually
large crop of mushrooms, which were more plentiful than usual
because of wet weather. Previous research has shown that fungi
take up more radioactivity from the soil than grasses or other
plants.

... the discovery of such high levels of radioactivity so long
after the Chernobyl accident came as a surprise. "No one at the
time expected contamination to be so high more than 20 years after
the event," he says.

This occurred a long distance from Chernobyl. I'd prefer that we
didn't poison ourselves in the search for fuel.

>coal (which can be made clean with the byproduct useful for making concrete
>stronger),

Coal is plentiful and can be made a cleaner source of energy, but it's
not happening yet:
http://environment.newscientist.com/channel/earth/dn9082-china-struggling-to-catch-its-breath.html;jsessionid=FGPEPLHHNEGB

>hydro-electric, wind and solar (and I don't mean PV cells).

Decentralizing electrical power is a great idea. Small wind turbines
seem like a good idea: http://www.quietrevolution.co.uk/

Another untapped power source, ocean waves, seems ripe to help fill
the need: http://en.wikipedia.org/wiki/Wave_power

>What I can't understand is why solar heat for your house isn't being
>pushed more. Unlike solar electric cells, solar heat can easily and
>quickly pay for it's self. In many parts of the country it can provide
>over 90% of your heating needs. The only disadvantage I can see, is for
>it to be most cost effective, you need to have it built into the house
>from the start. It's hard to add it to existing homes and have it be
>efficient unless certain things just happen to be right. That may be
>part of why it isn't talked about more.

Of course, solar swimming pool heating is being used extensively in
locations where it is feasible.

We seem to have strayed a bit from the topic of aviation, but I
believe you are correct in intimating that it will be an aggregate of
technologies that will eventually supplant middle east petroleum in
the US if we are to remain independent in the future.

On Tue, 9 Jan 2007 18:17:26 -0500, "Morgans"
> wrote in >:

>
>"Larry Dighera" > wrote
>
>> Electrically powered vehicles are the only hope to reduce the transfer
>> of wealth from the western world to the middle east, and reduce global
>> warming. If the US doesn't find some breakthrough technology soon,
>> we'll all be speaking Farsi before long. :-(
>
>How do you figure that?

Well, not the ONLY hope, but part of the solution to petroleum
independence.

>What do you suppose generates the majority of the electricity to recharge
>that car? Fossil fuels.

That is true today, but petroleum based energy sources should be
diverted over time to the manufacture of alternate energy producing
technology, rather than burned as motive fuels if the US is to slip
out of the middle east grip toward which it is headed.

>Until we start building nuke plants,

Not my first choice, nuclear has shown itself to be problematic in a
number of ways, financially, environmentally, politically ....

>or find a breakthrough in solar power generation, we will be stuck
>with the oil and gas noose around our necks.

I agree.

Currently, we are poised on the brink of a global revolution in
photovoltaic cell production. Manufacturing plants for new, cheaper
cell technologies that require less environmental impact to produce,
and higher efficiencies are slated to begin coming on now as supply is
unable to meet demand. Much of the venture capital that fueled the
dot com boom is being diverted toward solar technology startups. I
look for photovoltaic costs to decline and efficiencies to increase in
the near future. And with the power companies paying customers for
running their meters in reverse, the stage is set for decentralized
energy production in the US.

Larry Dighera wrote:
> Nuclear has shown itself to be problematic:
>
>
> http://environment.newscientist.com/channel/earth/dn10393-chernobyl-
> haunts-the-norwegian-uplands.html Chernobyl haunts the Norwegian
> uplands 12:00 28 October 2006
>
> This occurred a long distance from Chernobyl. I'd prefer that we
> didn't poison ourselves in the search for fuel.
>

That's what happens when you let a morally and finacially bankrupt country
play with fire. Overall Nuclear energy has a damn good safety record. There
is, of course, the issue of what to do with the waste but technology and
reuse of the material should be able to take care of that.

But the Chernobyl issue is also a symptom of the Big Nuke Plant that we and
virtually all other counties have used. The outcome of this is astonomical
costs for each plant because first they are so damn big and virtually each
one is designed on a clean sheet of paper.

On the other hand we have nuclear powered ships with smaller reactors that
are fairly uniform and have been proven to be very safe. And those reactors
are designed to be shot at.

Here's a cool idea that our own government came up with for developing
nations. I see no reason it couldn't be used on a local basis right here at
home. http://www.llnl.gov/str/JulAug04/Smith.html

On 9 Jan 2007 15:41:53 -0800, wrote in
om>:

>Larry Dighera wrote:
>> http://www.teslamotors.com/
>
>The real issue is probably the lack of a big enough market for such
>innovations in the GA sector.

That is an excellent point, as it always is when considering the
aviation market. Thank you for raising it.

>Aviation in general is a very hard business to make money in and
>even giants like Boeing and Airbus seem to be never too far from
>slippery ground.

However, new technologies do seem to appear in the aviation
marketplace regularly, the use of composites and titanium for aircraft
structures for instance. And an electrically powered aircraft was
recently certified, so there is evidence, that despite the small
aviation market, aviation still manages to lead the way in technologic
innovation to some extent.

On 2007-01-09, Larry Dighera > wrote:
> Charge time for the Altair batteries is only a few minutes as I
> recall.

I'm extremely skeptical - if these batteries are not snake oil, consider
this. Let's call "a few minutes" 10 minutes, and let's say the battery
pack stores 70kWh (enough to run a motor producing 94 hp for 1 hour).

To put 70kWh's worth into a battery pack in 10 minutes would require a
charger capable of putting out 420kW.

At 120 volts, 420kW would require a current of 3500 amps. Look at the
massive thick wire coming into your house (which maybe is rated at 80
amps).

Now let's say these batteries give three hours worth at 70kWh, and
charge in 10 minutes - now you're up to 10,500 amps at 120 volts. YOU
CANNOT AVOID high voltage, high amperage controls in a vehicle like the
Tesla, regardless of the battery technology. You are moving around
tremendous amounts of current. If this mythical charger was 99%
efficient, the 1% emitted as heat could heat an entire office building
in the dead of winter in central Canada. To consider this new battery
technology a silver bullet is to ignore the well established laws of
physics. Now imagine if *everyone* is charging their mythical car. No
practicable electricity distribution network that's feasable in the near
term could cope.

It would be totally and utterly impractical to charge these batteries at
this rate. I'll let you do the calculations for the equivalent in
electricity that filling a Cessna 150 with avgas in 4 minutes (the
typical time to do it at a self serve pump) would be.

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

> Consider that a Cessna 150 can fly for perhaps 3 hours, at 75% power. To
> get the equivalent range with batteries would require about 3,000 lb. of
> batteries, which would be totally impractical for an aircraft that now
> grosses at 1,600 lb.

How about fuel cells?

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.

On 2007-01-10, Larry Dighera > wrote:
> Vegetable oil seems like a great renewable alternative fuel to me. The
> question is, is there enough agricultural land to grow the amount
> necessary.

The trouble is the US is often looking at the wrong things for biofuels
because of the farming lobby wanting subsidies. There are much better
ways of making biofuel than using corn for ethanol.

Algae processes can deliver 10,000 us gallons/acre of biofuel (compared
with about 150 gal/acre for ethanol). It can be done as an industrial
process, using rust belt industrial land - no agricultural land needed.

Research on cellulosic ethanol continues. This means any old plant
matter will do. You can grow weeds in very poor soil, and make fuel from
that - you don't even need fertiliser, just find a vigorous invasive
plant and grow it on land marginal for agricultural use.

"In June 2006, a U.S. Senate hearing was told that the current cost of
producing cellulosic ethanol is US $2.25 per US gallon (US $0.59/litre).
This is primarily due to the current poor conversion efficiency. At
that price it is not competitive when distribution costs are added.
However, the Department of Energy is optimistic and has requested a
doubling of research funding. The same Senate hearing was told that the
research target was to reduce the cost of production to US $1.07 per US
gallon (US $0.28/litre) by 2012."

So there's far more than one source available, so long as politicians
aren't bought and paid for. Aviation will ALWAYS require a very high
energy density fuel, and no battery in the forseeable future will cut it
for practical aviation. But biofuels will.

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

On Wed, 10 Jan 2007 03:16:27 GMT, wrote in
>:

>Larry Dighera > wrote:
>> If an aircraft were covered in Spectrolab* triple-junction solar
>> cells, fuel would be free during the daylight, quiet, and pollution
>> free.
>
>You get something like 1 kW/m^2 of energy from the sun under good
>conditions, like being on the equator on a clear day in the summer. I
>think current PV cells are somewhere around 10% to 15% efficient,

That's why I specified the Spectrolab triple-junction photovoltaic
cells and provided a link to them. They are able to provide <30%
efficiency as they are tuned for red, blue and IR wavelengths.

> so that's 100-150 watts per square meter. Google says a Cessna 182 has
>about 16.2 m^2 of wing area, so you might get around 1.6-2.4 kW from
>solar cells covering the wings. You'd get a little more from the rest
>of the skin, but IMHO probably not more than 50% additional, or 2.4
>to 3.6 kW. That's 3.2 to 4.8 hp that the cells are contributing.

Assuming your figures are correct, and given the specified cells, that
figure could be 200% to 300% of your figures. It could take a day to
fully recharge a exhausted battery in locations where city power was
unavailable.

>Also, does the solar cell factory run on solar cells?

Ummm.. There is that issue, but Honda is addressing it. Search on
their web site for solar cells, and you will learn that they beginning
production of a new type of cell not based on silicon. It's
manufacture is supposed to reduce the environmental impact resulting
from their creation.

>> What is the weight of the Continental O-200 complete with its
>> manifolding, muffler, oil, and fuel?
>
>http://en.wikipedia.org/wiki/Continental_O-200 says about 170 lbs (77
>kg) dry for just the engine.

The Tesla Motors engine weighs less than 70 lbs per their specs.

>For an electric drive, in addition to the weight of the motor and
>batteries, you'll also need to figure in the weight of the inverter
>that changes DC into three-phase AC. Some of these inverters are
>air-cooled and some are liquid-cooled.

True. I read that the Tesla Motors system is liquid cooled.

>> http://www.wired.com/news/wiredmag/0,71414-0.html?tw=rss.index
>> Tesla has managed to produce an impractical and exorbitantly
>> expensive vehicle just as a revolutionary new battery has appeared
>> on the scene.
>
>I've only been involved in hybrid cars for about six years,

How are you involved in hybrid cars? As a manufacturer, designer,
prototype builder, driver, or what?

>but I've already seen a few "revolutionary new batteries" come and go.

True. GM's EV1 originally employed lead-acid batteries. The
follow-on integration used NiMH technology, but it wasn't a success
either. Clearly, GM lacks the creative insight to produce a viable
electric car. It's like teaching an elephant to dance.
http://en.wikipedia.org/wiki/Ev1

>Many of these batteries turn out to be quite good at ensuring a steady flow of
>press releases out and money in, but never quite manage to push any
>actual electrons.

Agreed. But lithium technology is used in millions of laptop
computers worldwide. It's mainstream, and proven (despite Sony's
manufacturing anomalies).

On Tue, 9 Jan 2007 21:24:33 -0500, "Capt. Geoffrey Thorpe" <The Sea
Hawk at wow way d0t com> wrote in
>:

>"Larry Dighera" > wrote in message
...
>> On Tue, 09 Jan 2007 18:20:07 GMT, "Neil Gould"
><...>
>> Perhaps the Tesla roadster doesn't need to develop 75 Hp during it's
>> entire run time, and there's the issue of regenerative braking, but
>> these things are not germane to electrically powered aircraft which
>> typically must produce 75% rated Hp continuously in cruise flight.
>>
>> Unlike automobiles, aircraft not only require motive power to propel
>> them forward, but they are not afforded the luxury of a roadway to
>> support their weight, and I would presume aircraft drag is
>> considerably more than an automobile.
>>
>
>That's probably not a good assumption.
>
>From http://www.t18.net/resources/T-18%20orig%20hdbk.doc page 34

(Perhaps you'd be good enough to cut and paste the reverent section
into a follow up. I'm uneasy opening MS Word documents from anonymous
sources.)

>An O-290 Powered T-18 can get 20+ miles per gallon at 170+ mph true air
>speed
>
>Not many gasoline powered cars can match this.

That's for sure, whether you're referring to automobile speed or MPG
of SUVs. :-)

James Robinson wrote:
>
> One of the closest is the liquafaction of coal. We have vast supplies in
> North America, and it is a relatively straight-forward process to convert
> it to liquid fuel. (see the Fischer-Tropsch process) The Germans and South
> Africans used synfuels made from coal when they couldn't get cheaper
> petroleum products. They worked well.

Okay, here's the aviation tie-in ...

The USAF recently flew a B-52 with synfuel made throught the FT
process. First flight was with 2 of 8 engines powered by synfuel; IIRC
subsequent flights had all 8 burning synthetic?

I think a combination of wind turbines and sea turbines would be a
great combination for limitless electrical power generation. Here's the
site for an interesting proposal.

http://www.capewind.org

Kingfish wrote:
> James Robinson wrote:
>>
>> One of the closest is the liquafaction of coal. We have vast
>> supplies in North America, and it is a relatively straight-forward
>> process to convert it to liquid fuel. (see the Fischer-Tropsch
>> process) The Germans and South Africans used synfuels made from coal
>> when they couldn't get cheaper petroleum products. They worked well.
>
> Okay, here's the aviation tie-in ...
>
> The USAF recently flew a B-52 with synfuel made throught the FT
> process. First flight was with 2 of 8 engines powered by synfuel; IIRC
> subsequent flights had all 8 burning synthetic?
>
> I think a combination of wind turbines and sea turbines would be a
> great combination for limitless electrical power generation. Here's
> the site for an interesting proposal.
>
> http://www.capewind.org

It's a great idea. Unfortunatly would be a huge "Not in my backyard" or more
to the point "Not in my ocean view" backlash against it.

Jose > wrote:

>> Consider that a Cessna 150 can fly for perhaps 3 hours, at 75% power.
>> To get the equivalent range with batteries would require about 3,000
>> lb. of batteries, which would be totally impractical for an aircraft
>> that now grosses at 1,600 lb.
>
> How about fuel cells?

What kind of fuel?

Liquid hydrogen tanks are something like 4 times the volume of avgas tanks
for the same energy. Where would you put them? Compressed hydrogen takes
even more space.

They also weigh substantially more, because of the need to contain and
insulate the hydrogen. Given the limited useful weight in a C150, adding
weight would be unproductive, if not impractical.

"James Robinson" > wrote in message
. ..
> Jose > wrote:
>
>>> Consider that a Cessna 150 can fly for perhaps 3 hours, at 75% power.
>>> To get the equivalent range with batteries would require about 3,000
>>> lb. of batteries, which would be totally impractical for an aircraft
>>> that now grosses at 1,600 lb.
>>
>> How about fuel cells?
>
> What kind of fuel?


Ammonia (NH3?)

Now you need a reformer.

James Robinson wrote:
> The batteries weigh 900 lb., and put out 75 HP for an hour. You wouldn't
> get too far on that in a C150.

you would save a noticeable amount of weight from not needing to carry
fuel (avgas is something like 6lbs per galon, so that would be approx
300lbs "offset" (not saved, but shifted to battery cell weight)
also, no oil (so thats a few more pounds)
and electric motors are fairly light compared to internal combustion
blocks


it would seem that powered gliders would benefit the most from this
tech because of their larger wingspan, mostly daylight operations (so
solar power), and they could probably recharge a little by spinning a
turbine when using airbrakes or something
(not a glider student and not an electircal engineer, so not really
sure about how useful this would actually be)

Recently, Dylan Smith > posted:

> On 2007-01-09, Larry Dighera > wrote:
>> Charge time for the Altair batteries is only a few minutes as I
>> recall.
>
> I'm extremely skeptical - if these batteries are not snake oil,
> consider this. Let's call "a few minutes" 10 minutes, and let's say
> the battery pack stores 70kWh (enough to run a motor producing 94 hp
> for 1 hour).
>
The Altair batteries are real, and a look at the Altair website reveals
its technology. Basically, they have created electrodes using
nanotechnology that eliminates the Solid Electrolyte Interphase barrier in
LI batteries.

http://www.altairnano.com/markets_amps.html

> To put 70kWh's worth into a battery pack in 10 minutes would require a
> charger capable of putting out 420kW.
>
Yes, and this is one of the reasons that I think their technology will be
of limited practicality for some common transportation uses.

> At 120 volts, 420kW would require a current of 3500 amps. Look at the
> massive thick wire coming into your house (which maybe is rated at 80
> amps).
>
> Now let's say these batteries give three hours worth at 70kWh, and
> charge in 10 minutes - now you're up to 10,500 amps at 120 volts.
>
Well, first, these are 13V batteries @ 88AH, so it would be good to do
power requirement calculations based on that. You can probably avoid high
voltage issues, but not high current issues. Based on Atlair's claim that
the batteries can be charged in *one* minute, you're still looking at some
beefy components for charging and controlling the discharge of these
batteries.

Neil

"mad8" > wrote:
>
> James Robinson wrote:
>>
>> The batteries weigh 900 lb., and put out 75 HP for an hour. You
>> wouldn't get too far on that in a C150.
>
> you would save a noticeable amount of weight from not needing to carry
> fuel (avgas is something like 6lbs per galon, so that would be approx
> 300lbs "offset" (not saved, but shifted to battery cell weight)
> also, no oil (so thats a few more pounds)
> and electric motors are fairly light compared to internal combustion
> blocks

Yes. If you saw my other post, I added up those numbers. You remove a bit
more than 400 lb total with the gasoline engine, and add more than 1000 lb.
with the batteries and electric motor, for a net add of 600 lb. That is
more than the aircraft can handle.

You also drop from a 4hr 30 minute endurance to a 60 minute endurance.

You really can't beat the energy density and low cost of liquid petroleum
fuels with today's technology.

"Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote in message
...
> Larry Dighera wrote:
>> http://www.teslamotors.com/
>
> Well they say the motor weighs 70 pounds and produces 248 HP but I can't
> find anything about the weight of the batteries.

Battery technology is coming down in weight very rapidly. That's
encouraging.

-c

Dylan Smith > wrote:

> Larry Dighera > wrote:
>>
>> Charge time for the Altair batteries is only a few minutes as I
>> recall.
>
> To put 70kWh's worth into a battery pack in 10 minutes would require a
> charger capable of putting out 420kW.

It implies that you would either have to physically swap the batteries, or
have some sort of energy storage device that could quickly dump its charge
into the battery. That storage device could then in turn by charged at a
more leisurely rate.

All of this adds to the expense of providing useable energy, and each
conversion step adds to the inefficiency of the whole cycle.

As you mention, the electricity grid does not have the capacity to handle
the amount of power needed to charge everybody's car without major
upgrading.

gatt wrote:

> Battery technology is coming down in weight very rapidly. That's
> encouraging.
>

Not really. If battery technology had kept up with computer technology over
the last 20 years you'd be able to power 747 accross the US with a batery
about the size of the one in your cell phone and it would cost about $5.00.

and every 15 minutes everyone on the aircraft would have to get out and
get back in...
/old IT joke

Gig 601XL Builder wrote:
> gatt wrote:
>
> > Battery technology is coming down in weight very rapidly. That's
> > encouraging.
> >
>
> Not really. If battery technology had kept up with computer technology over
> the last 20 years you'd be able to power 747 accross the US with a batery
> about the size of the one in your cell phone and it would cost about $5.00.

> wrote in message
ups.com...
> Actually, aircraft (specifically motor gliders) are far ahead!
>
> See: http://www.nadler.com/public/Antares.html
>
>
> It might take a little while before the power efficiency of batteries
> equals the needs of a useful airplane...

Most GA airplanes aren't necessarily "useful." They're just flown around
for the hell of it. Imagine if you could log an hour of training or
practice or do a quick photo sortie without burning fuel.

I'm just disappointed that the Big Ass Rubber Band (tm) technology never got
past the balsa aicraft stage. Must be a big oil conspiracy.

-c

Larry Dighera wrote (rather quoted a comment from wired.com):
> http://www.wired.com/news/wiredmag/0,71414-0.html?tw=rss.index
> The Tesla as it stands is obsolete if it doesn't use the new type
> batteries from Altair[**]. It will be the laughingstock of the
> business world if it delivers its current overly-complicated
> battery system, with its computers and sensors and HVAC system.

Larry, just BTW, the Altair Nano batteries this guy is going on
don't pass the sniff test very well...

Tesla isn't using them because Tesla wants to ship cars
sometime this decade.

Altair claims that WRT conventional graphite electrode lithium-ion
batteries, their TiO nano-granule electrode lithium-ion batteries
have 3X the energy density, 60X the max charge rate, and 10X
the charge-cycle lifetime.

If these batteries actually existed in a form that would allow
Tesla to ship 200 cars this year, you would think that every
single cell phone and laptop in the universe would be running
on them, wouldn't you? I mean, *I* want my cell phone charge
to last 2 weeks instead of 5 days, *I* want to be able to charge
my laptop in 1 minute, and then have it last through an entire
8-hour flight, *I* want my cell phone battery to
last longer than the phone instead of having to replace the
battery after 18 months.

But yet I can't go to batteries.com and buy one of these
wonderful batteries that Tesla is so stupid for not using.
I think there *might* be a reason for that. :-)

BTW, this press release:
http://www.autobloggreen.com/2006/12/29/altair-nanotechnologies-ships-first-10-batteries-to-phoenix-moto/

seems to indicate that Altair's entire production volume of batteries
to date is 10 35kWh battery packs for $750,000. It apparently
took 30 days (well, that includes Christmas) to deliver all 10 battery
packs.

I hope Altair and Phoenix are fabulously successful, but there is
good reason for skepticism.

-Jay-

Larry Dighera > wrote:

> wrote
>>
>> Google says a Cessna 182 has about 16.2 m^2 of wing area, so you
>> might get around 1.6-2.4 kW from solar cells covering the wings.
>> You'd get a little more from the rest of the skin, but IMHO probably
>> not more than 50% additional, or 2.4 to 3.6 kW. That's 3.2 to 4.8 hp
>> that the cells are contributing.
>
> Assuming your figures are correct, and given the specified cells, that
> figure could be 200% to 300% of your figures. It could take a day to
> fully recharge a exhausted battery in locations where city power was
> unavailable.

Just what size battery are you thinking of? If you want to have a
battery that has the same capacity as the fuel tank in a 182, you would
need about 1000 kW-hr, or one 15 times the size of that in the Tesla
sports car.

The amount of power available from the sun is usually quoted in sun-days,
which is typically about 5 hours for the sunny areas in the south, like
west Texas.

Given a 5 hour sun-day, and a 5 kW solar panel arrangement, it would take
about 40 days to fully recharge the batteries, assuming 100 percent
efficiency of the charging circuit.

Further, batteries that can withstand high charge and discharge rates
often have associated high internal leakage, meaning that they lose their
charge rather quickly while sitting on the shelf. That means the charger
not only has to supply the charge itself, but also make up for the loss
from internal discharge. If you combine a realistic efficiency for the
charger with the realities of internal discharge, you might never see the
battery fully charged with the solar panels alone.

We also haven't added up the cost and weight of the batteries yet, not to
mention the cost and weight of the solar panels.

> The Tesla Motors engine weighs less than 70 lbs per their specs.

The Tesla motor will also not be sized for a continuous duty. They are
relying on the fact that an automobile only needs horsepower for short
bursts of acceleration, and practically loafs along the rest of the time.
Just think about how little you need to depress the accelerator pedal
when cruising along in your car.

An aircraft needs to have a power source that can provide high power for
long periods. Electric motors would therefore have to be sized
appropriately. In the case of industrial 3 phase motors, they typically
weigh 1 lb. per horsepower. Therefore, a motor large enough to power a
182 would weigh close to 200 lb.

> Clearly, GM lacks the creative insight to produce a viable
> electric car. It's like teaching an elephant to dance.

Not at all. GM has the imagination, it's just that the technology is not
there yet. It is too expensive, and there are too many limitations for
it to complete with internal combustion engines as things stand today.

> Agreed. But lithium technology is used in millions of laptop
> computers worldwide. It's mainstream, and proven (despite Sony's
> manufacturing anomalies).

Yes, and it is very expensive. Even with cheaper lead-acid batteries, a
replacement set of batteries (800 lb.) for the Toyota RAV was something
like $15,000. Lithium batteries are something like 4 times that cost
today, or $60,000 for a set of batteries for a car. How many people will
spend that kind of money?

James Robinson wrote:
> Larry Dighera > wrote:
>
>> Clearly, GM lacks the creative insight to produce a viable
>> electric car. It's like teaching an elephant to dance.
>
> Not at all. GM has the imagination, it's just that the technology is
> not there yet. It is too expensive, and there are too many
> limitations for it to complete with internal combustion engines as
> things stand today.
>

Speaking of GM. Here's their newest electric concept car.

http://www.canada.com/topics/finance/story.html?id=4adec548-a654-4000-8b3c-aff0354600aa&k=45978

Check out the batteries from A123 Systems:
http://www.a123systems.com/html/technology.html

Li Ion batteries made with iron at 1/5 the price, twice the power and
half the weight of conventional Li Ions.
They are already on the market and are starting to show up in
DeWalt's/Bosch 36V cordless tools.
They have a weight to Watt ratio less than 1 lb / 1500W ( .9 to be
exact).

Scheeesch if their stock ever goes public, I'll be standing in long
line of buyers.


> > Agreed. But lithium technology is used in millions of laptop
> > computers worldwide. It's mainstream, and proven (despite Sony's
> > manufacturing anomalies). Yes, and it is very expensive. Even with cheaper lead-acid batteries, a
> replacement set of batteries (800 lb.) for the Toyota RAV was something
> like $15,000. Lithium batteries are something like 4 times that cost
> today, or $60,000 for a set of batteries for a car. How many people will
> spend that kind of money?

JD writes:

> They have a weight to Watt ratio less than 1 lb / 1500W ( .9 to be
> exact).

A watt is not a measure of energy storage. Perhaps you are thinking
of watt-hours or something similar?

Also, the greater the energy density, the greater the potential hazard
(as already exists with many lithium batteries).

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Jan 10, 3:16 pm, Mxsmanic > wrote:
> JD writes:
> > They have a weight to Watt ratio less than 1 lb / 1500W ( .9 to be
> > exact).A watt is not a measure of energy storage. Perhaps you are thinking
> of watt-hours or something similar?
>
> Also, the greater the energy density, the greater the potential hazard
> (as already exists with many lithium batteries)>
> --
> Transpose mxsmanic and gmail to reach me by e-mail.

These Li-Ions don't have the same safety problem as the conventional
because of the Iron.
from their website on this subject:

"A123 M1 cells are intrinsically safe and eliminate the risk of
explosions and thermal runaway associated with conventional Lithium-Ion
batteries that use oxide active materials. To achieve this, the active
materials in A123's technology are not combustible and do not release
oxygen if exposed to high temperature or in the event of battery
failure or mechanical abuse."

Yea.. I'm not real sure about the units here... but they do site a
power density of 2700W/Kg see:
http://www.a123systems.com/html/tech/power.html

JD wrote:
> Yea.. I'm not real sure about the units here... but they do site a
> power density of 2700W/Kg see:
> http://www.a123systems.com/html/tech/power.html

They're pretty clearly talking about power density, not
energy density. Both their language and their units
reflect power density.

Power density isn't the issue for long-distance cruising.
It might be somewhat relevant if you were wanting to
build the fastest possible dragster for a 100 yard sprint.
But energy density is the problem that most battery
powered vehicles have when compared to petroleum
powered vehicles, especially for long distance cruising.

"Larry Dighera" > wrote in message
...
> On Tue, 9 Jan 2007 21:24:33 -0500, "Capt. Geoffrey Thorpe" <The Sea
> Hawk at wow way d0t com> wrote in
> >:
<...>>
>>From http://www.t18.net/resources/T-18%20orig%20hdbk.doc page 34
>
> (Perhaps you'd be good enough to cut and paste the reverent section
> into a follow up. I'm uneasy opening MS Word documents from anonymous
> sources.)
>
Gee, I can't imagine why...

Not sure how the formatting will come out but here is data for one T-18:



CRUISE PERFORMANCE



Standard Temperature, Lean Mixture, 135 BHP used as 100% Power Base



% TAS %
TAS

POWER RPM MPH GPH MPG POWER RPM MPH GPH MPG



SEA LEVEL 2000 FT



50 2060 137 5.6 24.5 50 2100
137 5.6 24.4

60 2320 154 6.6 23.3 60 2360
154 6.6 23.2

70 2490 165 7.5 21.9 70
2540 166 7.6 21.8

75 2550 170 8.0 21.2 75
2600 171 8.1 21.2

80 2610 174 8.4 20.6 80
2660 175 8.5 20.6

90 2730 181 9.3 19.4 90
2780 182 9.4 19.4

100 2820 187 10.2 18.4 100 2870
188 10.3 18.3

114 2910 194 11.3 17.2 107 2910
192 10.8 17.8





% TAS %
TAS

POWER RPM MPH GPH MPG POWERRPM MPH GPH MPG



4000 FT 6000 FT



50 2120 137 5.6 24.3 50
2140 137 5.7 24.2

60 2390 154 6.7 23.1 60
2420 155 6.7 23.1

70 2570 167 7.6 21.9 70
2600 168 7.7 21.9

75 2640 172 8.1 21.2 75
2670 174 8.1 21.4

80 2710 176 8.6 20.6 80
2740 179 8.6 20.8

90 2810 183 9.4 19.4 90
2840 186 9.5 19.6

100 2910 189 10.3 18.3 94 2880
188 9.8 19.1





% TAS %
TAS

POWER RPM MPH GPH MPG POWER RPM MPH GPH MPG



8000 FT 10000 FT



50 2160 137 5.7 24.1 50
2180 136 5.7 23.9

60 2440 156 6.7 23.2 60
2450 158 6.7 23.5

70 2620 172 7.7 22.4 70
2650 176 7.7 22.8

75 2700 178 8.2 21.8 75
2730 183 8.2 22.3

80 2780 183 8.7 21.2 80
2810 188 8.7 21.6

86 2830 189 9.2 20.6



Power and fuel flow data are based on Lycoming performance charts for the
0-290-D2, dependent upon Manifold Pressure, RPM, OAT, and Pressure Altitude.
Speeds based on speed course calibrated airspeed system.




fwiw:

t18.net is a pretty good place to get infomation. By T-18 builders for T-18
builders

The guy who wrote the aircraft handbook that I copied this from is a very
meticulous Aero engineer who used to work in flight test for one of the big
aerospace companies in the U.S. He puts a lot of effort into the details -
his O-290 T-18 is as fast as many of the O-360 powered T-18's And, knowing
how he works - I would trust his data before I would trust any of mine...


--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

("James Robinson" wrote)
> An aircraft needs to have a power source that can provide high power for
> long periods. Electric motors would therefore have to be sized
> appropriately. In the case of industrial 3 phase motors, they typically
> weigh 1 lb. per horsepower. Therefore, a motor large enough to power a
> 182 would weigh close to 200 lb.


The Cri-Cri would need two electric motors, weighing (approx) 15 lbs each.
Current 15 hp (gasoline) engines weigh upwards of 25 lbs. each (with exhaust
pipes, starters, oil, etc) So, that would be an additional 20 lb savings
....(call it 15 lbs. total)

Gasoline fuel at takeoff is 35 lbs (Includes the tank)

So that's 35 lbs toward the weight of a battery ...plus the 15 lbs from the
engines = 50 lbs in savings we can give over to the battery.

Forgetting about cross-country capabilities:

If a Cri-Cri were to be set up with electric motors and a battery, how big
(heavy) would the battery need to be to allow the pilot to: Take-off, fly
around for 15 minutes at 100 kts, and land?

Cri-Cri (gasoline)
Empty weight ....... 180 lbs
MTOW .................. 400 lbs
Cruise Speed ...... 100 kts

I've got to believe we could find some more weight savings in those two
Cri-Cri electric motors.


Montblack

On Tue, 9 Jan 2007 at 14:38:16 in message
>, Larry Dighera
> wrote:

>http://www.teslamotors.com/

Interesting. I see Vauxhall in the UK have just launched a similar car.

Environmentally they do not produce much pollution on the road but, of
course, where they do create it is at the providing power station
(except for Nuclear of course).

I am prejudiced - I have just purchased a Toyota Prius! Nothing like as
sporty of course!

Batteries will have to have a very great capacity for their weight to
make a normal aircraft successful.
--
David CL Francis

> > How about fuel cells?
>
> What kind of fuel?
>
> Liquid hydrogen tanks are something like 4 times the volume of avgas tanks
> for the same energy. Where would you put them? Compressed hydrogen takes
> even more space.
>
> They also weigh substantially more, because of the need to contain and
> insulate the hydrogen. Given the limited useful weight in a C150, adding
> weight would be unproductive, if not impractical.

A long time ago I read an article proposing an electric powered
airplane with a hydrogen/oxygen fuel cell - which would run on Hydrogen
Peroxide (H2O2). The peroxide would be catalytically separated into the
component elements, then fed to the fuel cell. It sounded plausible
except for one thing - peroxide is nasty stuff. I wouldn't want to be
either handling it or hauling it around.

David Johnson

David Johnson

"Dave" > wrote in message
oups.com...

> A long time ago I read an article proposing an electric powered
> airplane with a hydrogen/oxygen fuel cell - which would run on Hydrogen
> Peroxide (H2O2). The peroxide would be catalytically separated into the
> component elements, then fed to the fuel cell. It sounded plausible
> except for one thing - peroxide is nasty stuff. I wouldn't want to be
> either handling it or hauling it around.
>
> David Johnson

I was involved in a project like that a few years ago. It literally never
got off the ground. This project had no plans for a reformer.

Phase I - Flight on Batteries

Phase II - Flight on Batteries assisted by fuel cell

Phase III - flight on Fuel Cell assisted by batteries.

The airframe is a French made carbon fiber (Ghiles?). The motor was UQM
(Unique mobility - supposed to be the same one used by BMW)

James Robinson wrote:

> Liquid hydrogen tanks are something like 4 times the volume of avgas tanks
> for the same energy. Where would you put them? Compressed hydrogen takes
> even more space.
>
> They also weigh substantially more, because of the need to contain and
> insulate the hydrogen. Given the limited useful weight in a C150, adding
> weight would be unproductive, if not impractical.


My understanding was that liquid hydrogen gave the most energy per unit
mass of any other fuel, which is why it is used in the space shuttle.
The down side being that the amount of energy to make the hydrogen and
then liquefy it is far greater than the amount of energy you get out of
it. Such a system may not scale down well though.


--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,
learn more at http://www.defectivebydesign.org/what_is_drm"

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
One stop wish list for any gift,
from anywhere, for any occasion!
http://thewishzone.com

Larry Dighera > wrote:
> On Wed, 10 Jan 2007 03:16:27 GMT, wrote in
> >:
>
>>Larry Dighera > wrote:
>>> If an aircraft were covered in Spectrolab* triple-junction solar
>>> cells, fuel would be free during the daylight, quiet, and pollution
>>> free.
>>
>>You get something like 1 kW/m^2 of energy from the sun under good
>>conditions, like being on the equator on a clear day in the summer. I
>>think current PV cells are somewhere around 10% to 15% efficient,
>
> That's why I specified the Spectrolab triple-junction photovoltaic
> cells and provided a link to them. They are able to provide <30%
> efficiency as they are tuned for red, blue and IR wavelengths.

The "data sheet" Spectrolab provides lists some typical parameters,
including an efficiency of 27 +/- 3% absolute. They don't list the
minimum parameters. But let's be optimistic and say that they really
do give you 30%, or 300 watts per square meter. With 16.2 m^2 of wing
(Cessna 182), you'd get 4.86 kW from the wing cells. Add 50% for the
rest of the skin for 7.3 kW or 9.8 hp total.

> It could take a day to fully recharge a exhausted battery in locations
> where city power was unavailable.

Let's assume that a "day" is 12 hours and you get the above 7.3 kW/
9.8 hp from the cells for all 12 hours. That'd give you 87 kWhr or
117 hphr. Wikipedia's entry for the 182 says its IO-540 develops
230 hp, so those 12 hours of charging would buy you just a bit over
half an hour of flight at full power, or a bit over an hour of flight
at an average of 50% power. Charge 12 hours, fly one hour. Hmm.

> Search on their web site for solar cells, and you will learn that
> they beginning production of a new type of cell not based on silicon.

I found the press release and it does look interesting. It didn't say
if the factory would run on solar cells, though.

>>> What is the weight of the Continental O-200 complete with its
>>> manifolding, muffler, oil, and fuel?
>>
>>http://en.wikipedia.org/wiki/Continental_O-200 says about 170 lbs (77
>>kg) dry for just the engine.
>
> The Tesla Motors engine weighs less than 70 lbs per their specs.

If the O-200 is in a 150 with 22.5 gallons of usable fuel, and is being
operated at 75% power (best economy), it uses 6 gph. If you took off
full and landed just as the engine died from lack of fuel, you'd be in
the air for about 3 hours and 45 minutes. (I know it's not legal nor
a good idea to fly to the very end of the fuel.) That means the engine
has to be able to put out 75 hp for 3.75 hours without melting. If you
had a 30 minute turn, that would be an 88% duty cycle.

If you assume the motor in a Tesla Roadster is 90% efficient, then to
get 75 hp out, you'd need to put 83.3 kW in. If the battery has a
capacity of 56 kWh, and you drove the car such that the motor was
producing 75 hp continuously, that means you get to drive for about
40 minutes before the battery is dead. At that point it takes 3.5
hours to fully charge the battery, which is a 19% duty cycle.

It doesn't seem unusual to me that your powerplant can have less than
half of the weight, if it only needs to work for less than a quarter of
the time.

(C-150 numbers from
http://flighttraining.aopa.org/learntofly/articles/0108.cfm , Tesla
numbers from http://en.wikipedia.org/wiki/Tesla_Roadster .)

>>I've only been involved in hybrid cars for about six years,
>
> How are you involved in hybrid cars? As a manufacturer, designer,
> prototype builder, driver, or what?

As a prototype builder and a driver. I work on a university hybrid
car project, which has built three hybrids so far and is working on a
fourth. I've owned a Toyota Prius since spring 2001.

> Clearly, GM lacks the creative insight to produce a viable electric
> car.

I'm not sure that's the problem; I think it's more that they haven't
been able to get Congress to repeal those pesky laws of thermodynamics.
I also think GM has plenty of smart _engineers_ that could design good
hybrids and alternative fuel vehicles, but they don't have the
_management_ to actually pull it off.

> But lithium technology is used in millions of laptop computers
> worldwide. It's mainstream, and proven (despite Sony's manufacturing
> anomalies).

To me, "mainstream" means at least that I can buy one from Digi-Key.
(Being able to buy one at Wal-Mart would be even better.) I don't
disagree that current (ha) lithium battery technology is "mainstream",
but Altair is making some impressive claims. It would be interesting
to put their batteries in one of the hybrids at work and drive it around
town, slamming 200 A in and out of them for a while, and see how well
they work then.

Matt Roberds

Montblack > wrote:
> If a Cri-Cri were to be set up with electric motors and a battery, how
> big (heavy) would the battery need to be to allow the pilot to: Take-
> off, fly around for 15 minutes at 100 kts, and land?

You could put an absolute upper bound on it by assuming 100% power all
the time. With 30 hp of 90% efficient electric motor and 90% efficient
inverter/wiring, you'd need to draw about 37 hp or 28 kW from the
batteries. For 15 minutes total flight time, that's about 6.9 kWh.

If you use a Hawker/Invensys Genesis 70 Ah (nominal) battery and run it
to 1.5 volts per cell over 15 minutes at 25 C, you get 0.5101 kWh. You'd
need 14 of these batteries to get the 6.9 kWh. At 53.5 lb each, that's
749 lb (340 kg) of batteries. I'm using the Genesis battery as an
example because I've seen them actually deliver their stated ratings in
this kind of service. It is a lead-acid AGM battery and so is relatively
heavy.

Altair has a graph on their Web site that seems to show that their
batteries will give 90 Wh/kg at a 15-minute discharge rate. On the
other hand, that graph also has "Altair's Disruptive Technology" written
on it, which means it was probably produced by salesmen and not engineers.
If you take the 90 Wh/kg at face value, you'd need about 169 lb (77 kg)
of batteries.

Of course, if the overall average power setting is lower, you can get
away with fewer batteries.

Charging either kind of battery is probably going to be limited by the
charger, not by the batteries themselves. If everything is great, you
can plug your 90% efficient charger into a 125 V circuit and pull 15 A,
to get 1.875 kW in and 1.688 kW out. You usually have to return
something like 110% of the energy you took out of the battery, so you'd
need to put about 7.6 kWh into the battery. The recharge time would
therefore be about 4.5 hours. In continental Europe you might be able
to pull 16 A from a 230 V circuit, cutting the recharge time to about
2.3 hours. If you could pull 100 A at 240 V (the entire electrical
service of many houses in the US), you could recharge in about 21
minutes.

Matt Roberds

Chris W > wrote:

> James Robinson wrote:
>
>> Liquid hydrogen tanks are something like 4 times the volume of avgas
>> tanks for the same energy. Where would you put them? Compressed
>> hydrogen takes even more space.
>>
>> They also weigh substantially more, because of the need to contain
>> and insulate the hydrogen. Given the limited useful weight in a
>> C150, adding weight would be unproductive, if not impractical.
>
> My understanding was that liquid hydrogen gave the most energy per
> unit mass of any other fuel, which is why it is used in the space
> shuttle. The down side being that the amount of energy to make the
> hydrogen and then liquefy it is far greater than the amount of energy
> you get out of it. Such a system may not scale down well though.

You are correct that the hydrogen itself is very light for each unit of
energy. The problem is the weight of the container necessary to hold
that energy.

Hydrogen molecules are the smallest in nature, and as such, they will
more easily pass through container walls than other types of energy
source. That means any containers have to be more complicated than a
simple tank that holds fuel like avgas. They are typically built with a
number of layers to not only resist impact and rupture, but they also
have to be thick enough to keep hydrogen leakage to a minimum.

If made with steel, they have to be extra thick because hydrogen affects
the physical properties of steel over time, making the steel more
brittle. This hydrogen embrittlement means that any steel vessels have
to be extra thick to retain their ability to resist impacts. Layers of
other materials can help, but not eliminate the problem.

These requirements mean that the containers will necessarily be heavy.
Further, the containers typically have to be cylindrical in shape,
because of the pressures involved. Finding convenient places to put
cylinders in an aircraft would be a challenge.

Here is a web site that seems to do a good job of describing the issues
with hydrogen containment:

http://www.aip.org/tip/INPHFA/vol-10/iss-1/p20.html

On Wed, 10 Jan 2007 09:17:02 -0600, "Gig 601XL Builder"
<wrDOTgiaconaATsuddenlink.net> wrote in
>:

>On the other hand we have nuclear powered ships with smaller reactors that
>are fairly uniform and have been proven to be very safe. And those reactors
>are designed to be shot at.

Have any been hit yet? Would the public be made aware by the military
of the consequences of such an event?

>Here's a cool idea that our own government came up with for developing
>nations. I see no reason it couldn't be used on a local basis right here at
>home. http://www.llnl.gov/str/JulAug04/Smith.html

Interesting. Unfortunately the NRC has had to reduce its
certification standards to accommodate it:

License-by-Test Certification
NRC plans to certify the SSTAR design using a new license-by-test
approach, rather than the license-by-design approach that it used
to certify most of the existing commercial nuclear power plants.
NRC’s license-by-test process is similar to the certification
process used by the U.S. Federal Aviation Administration for
commercial airliners. To be certified, the SSTAR prototype must
demonstrate in a test environment that it can safely withstand
accidents, including the most improbable ones such as failure of
the active shutdown and shutdown heat-removal systems.
But the tri-laboratory collaboration has more work to do before an
SSTAR demonstration. According to Smith, the team plans to refine
the SSTAR design and then develop a prototype reactor, which could
be ready for testing as early as 2015. The Livermore team feels
confident that SSTAR will provide a new-generation reactor—one
that is safe, proliferation-resistant, and able to operate
anywhere in the world.

Unlike airliner certification, in which the test pilot can bail out if
things go awry, if a nuclear release should occur as a result of SSTAR
testing, our progeny will be paying the price for it for centuries.
Don't be duped by corporate avarice.

When our nation's nuclear waste begins to be transported on our
highways (if the decades long debate over where to house it for
thousands of years is ever settled), then we'll begin to see how safe
it is. And because of the limited lifetime of nuclear reactors (~25
years) and the cost of decommissioning them (sawing up the
contaminated concrete, transporting it, and storing it), and the cost
of storing the nuclear waste, and the cost of cleaning up after
nuclear incidents like Three Mile Island, we don't yet know how
economically feasible nuclear power really is in this country (USA).

But we're getting pretty far afield from the subject....

On Tue, 09 Jan 2007 22:54:18 -0600, James Robinson >
wrote in >:

[...]

>Well, let's look at some numbers. A gasoline aero engine of that size is
>typically about 2 lb. per HP, so a 100 HP engine would weigh about 200
>lb. I believe the O-235 is listed at 215 lb., with supplies, so it's in
>the ballpark.

Someone earlier in this message thread indicated that the 100 Hp Cont.
O-200 weighs ~200 lbs, so it would seem your assumptions are on target
so far.

>In comparison, three phase motors typically weigh about 1 lb. per
>horsepower. That would mean a 100 hp motor would weigh about 100 lb. I
>suspect that the Tesla's motor weighs less, because it is rated for less
>continuous duty than would be necessary on an aircraft.

It would be good to know how exactly the Tesla Motors 75 Hp motor is
rated. It is apparently able to produce considerably more than twice
that power for acceleration.

>An automobile engine practically loafs along when on the highway at constant
>speed, and only needs to have power for short bursts of speed. An aircraft engine,
>on the other hand, operates at high power for hours on end.

This is the crux of the issue.

>The fuel and tanks would also be unnecessary with an electrically-powered
>aircraft. A typical C-150 has something like a 26 gallon capacity. At 6
>lb. per gallon, that would be 136 lb. Add roughly 20 percent to that to
>account for the weight of the tanks, or 27 lb, for a total of about 165
>lb. for the fuel plus the tanks. The grand total being 215 + 165 = 380
>lb. Some additional amount could be added for fuel lines, filters and
>pumps, but they would be relatively small. As a round number, lets say
>everything weighs 400 lb.
>
>So, if we take out the IC engine, and replace it with the batteries used
>in the Tesla, and an appropriate electric motor, we would take out 400
>lb., and add 900 plus 100 lb. for the batteries and motor, assuming the
>ligher weight, plus some additional for the electrical control system an
>wiring. Even without the control system, we would have a net gain in
>weight of about 600 lb. Considering that a C150 has a usable capacity of
>only 370 lb. or so with full fuel, The electically-powered aircraft would
>already be more than 200 lb. overloaded, and we haven't even considered
>the pilot, passenger, or baggage. Doesn't sound too practical, does it?

Now that you put it that way, reality is beginning to dawn on me.

I would think that the LiIon cells could be made lighter if
specifically designed for aviation use. Currently they are steel
jacketed AA sized. Steel might be replaced with Titanium (atomic
number 22). Lithium (atomic number 3) is a light metal as is the
carbon (atomic number 6) anode.

You seem to have a firm grasp of the issue. Given:

http://en.wikipedia.org/wiki/Lithium_ion_battery
Lithium ion battery
Specific energy density: 150 to 200 W·h/kg (540 to 720 kJ/kg)
Volumetric energy density: 250 to 530 W·h/L (900 to 1900 J/cm3)
Specific power density: 300 to 1500 W/kg (@ 20 seconds [2] and 285
W·h/L)


http://en.wikipedia.org/wiki/Gasoline
Gasoline
Energy content
Fuel type Megajoules/L MJ/kg BTU/US gal
Premium Gasoline 32.84 43.50 131,200

Can you quantify the prospect of replacing Avgas with LiIon batteries?

wrote)
>> If a Cri-Cri were to be set up with electric motors and a battery, how
>> big (heavy) would the battery need to be to allow the pilot to: Take-off,
>> fly around for 15 minutes at 100 kts, and land?

> Altair has a graph on their Web site that seems to show that their
> batteries will give 90 Wh/kg at a 15-minute discharge rate. On the other
> hand, that graph also has "Altair's Disruptive Technology" written on it,
> which means it was probably produced by salesmen and not engineers. If you
> take the 90 Wh/kg at face value, you'd need about 169 lb (77 kg) of
> batteries.


This is why I love these groups!!

Thanks for the answer.

Ok, so 170 lbs worth of batteries it is! :-)

I have 50 lbs 'to give' swapping over to electric. So now all I need to do
is find 120 remaining lbs (55 kg) of weight, and shave THAT off the Empty
Weight of the Cri-Cri.

Gotta start somewhere! <g>


Montblack

http://www.technologyreview.com/Energy/18054/

describes GM's plans to build car with A123 System Li Ion batteries

James Robinson wrote:

> You are correct that the hydrogen itself is very light for each unit of
> energy. The problem is the weight of the container necessary to hold
> that energy.
>
> Hydrogen molecules are the smallest in nature, and as such, they will
> more easily pass through container walls than other types of energy
> source. That means any containers have to be more complicated than a
> simple tank that holds fuel like avgas. They are typically built with a
> number of layers to not only resist impact and rupture, but they also
> have to be thick enough to keep hydrogen leakage to a minimum.
>
> If made with steel, they have to be extra thick because hydrogen affects
> the physical properties of steel over time, making the steel more
> brittle. This hydrogen embrittlement means that any steel vessels have
> to be extra thick to retain their ability to resist impacts. Layers of
> other materials can help, but not eliminate the problem.
>
> These requirements mean that the containers will necessarily be heavy.
> Further, the containers typically have to be cylindrical in shape,
> because of the pressures involved. Finding convenient places to put
> cylinders in an aircraft would be a challenge.

I was aware of the difficulties in containing the hydrogen, but I was of
the impression that the weight of the container was more than
compensated by the energy to weight ratio of the liquid hydrogen. If
not, why would they use it on the space shuttle? That's not to say that
what works on the space shuttle will work well in an airplane. The
shuttle can be fulled shortly before it is launched, and then burns off
all of it's fuel in just a few minutes. I assume that would allow for
the tank to be lighter than it would have to be if it need to store the
hydrogen for a long period. I also know that things that work on a
large scale often don't work very well on a smaller scale.


--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,
learn more at http://www.defectivebydesign.org/what_is_drm"

Gift Giving Made Easy
Get the gifts you want &
give the gifts they want
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from anywhere, for any occasion!
http://thewishzone.com

On 11 Jan 2007 08:38:33 -0800, "JD" > wrote in
. com>:

>http://www.technologyreview.com/Energy/18054/
>
>describes GM's plans to build car with A123 System Li Ion batteries

Here's another link to information about GM's 'Volt prototype hybrid
automobile dated Jan. 7, 2007.


http://www.canada.com/topics/finance/story.html?id=4adec548-a654-4000-8b3c-aff0354600aa&k=45978&p=2
Lutz said the engineering development of the car itself is 18
months from being completed. The batteries are about 18 months
behind the rest of the car.

How many years would that put GM's product behind the Japanese? :-(

Chris W > wrote:
> I was aware of the difficulties in containing the hydrogen, but I was
> of the impression that the weight of the container was more than
> compensated by the energy to weight ratio of the liquid hydrogen. If
> not, why would they use it on the space shuttle?

Actually there was (and still is) considerable debate on the value of using
liquid hydrogen for rockets - with a fair number of people who consider the
decision to use liquid hydrogen for the shuttle as a design mistake. If you
Google past discussions on groups like sci.space.policy or sci.space.tech
you'll find long-running debates on this issue.

Montblack > wrote:
> Thanks for the answer.

You're welcome.

> Ok, so 170 lbs worth of batteries it is! :-)

If you believe Altair. :) One rule of thumb for rechargeable batteries
is to apply a correction factor of 0.5 to the numbers the salesman
emits, which puts you up to 340 lbs. Also, call them up and see if they
can sell you some of their batteries if you give them a credit card
number. If they can't, then as far as you're concerned, their batteries
don't really exist.

> I have 50 lbs 'to give' swapping over to electric. So now all I need
> to do is find 120 remaining lbs (55 kg) of weight, and shave THAT off
> the Empty Weight of the Cri-Cri.

Say the Battery Fairy gave you some batteries with an energy density
equal to gasoline. Then, going electric would let you lose the carbs,
cylinders, and exhaust pipes, which would probably help the drag a
little. The shape of an electric motor would make it easy to have a
nice smooth fairing over it, right behind the prop hub. Unfortunately
I've been putting dead D cells under my pillow for years and the Battery
Fairy has never shown up for me.

I wonder what a G1000 weighs, compared to steam gauges. :)

Matt Roberds

Larry Dighera > wrote:
> On Tue, 09 Jan 2007 22:54:18 -0600, James Robinson >
> wrote in >:
>
>> Considering that a C150 has a usable capacity of only 370 lb. or so
>> with full fuel, The electically-powered aircraft would already be
>> more than 200 lb. overloaded, and we haven't even considered the
>> pilot, passenger, or baggage. Doesn't sound too practical, does it?
>
> Now that you put it that way, reality is beginning to dawn on me.

It's almost like all those engineers working at Cessna and Boeing and
all the rest really _do_ know what they're doing when they pick internal
combustion engines fueled by liquid hydrocarbons. :)

> Given:
>
> http://en.wikipedia.org/wiki/Lithium_ion_battery
> Lithium ion battery
> Specific energy density: 150 to 200 W?h/kg (540 to 720 kJ/kg)
> Volumetric energy density: 250 to 530 W?h/L (900 to 1900 J/cm3)
> Specific power density: 300 to 1500 W/kg (@ 20 seconds [2] and 285
> W?h/L)
>
> http://en.wikipedia.org/wiki/Gasoline
> Gasoline
> Energy content
> Fuel type Megajoules/L MJ/kg BTU/US gal
> Premium Gasoline 32.84 43.50 131,200
>
> Can you quantify the prospect of replacing Avgas with LiIon batteries?

The numbers are there, you just have to deal with metric prefixes a
little bit. Li-ion at 540-720 kJ/kg is 0.540-0.720 MJ/kg. Therefore,
the energy in a kilogram of premium gasoline is equal to the energy in
(43.50/0.720) to (43.50/0.540) or about 60 to 80 kg of Li-ion batteries.

If you consider the whole system, you can get away with fewer batteries,
because electric motors in general are better at converting electrical
to mechanical energy than internal combustion engines are at converting
chemical to mechanical energy. If your engine is 30% efficient, you
only get (43.5 * 0.3) or 13.1 MJ of mechanical energy for every kilogram
of gasoline you burn. If your motor is 90% efficient, then to get that
same 13.1 MJ of mechanical energy, you need to put in about (13.1/0.9)
or 14.5 MJ of electrical energy. This would require (14.5/0.720) to
(14.5/0.540) or about 20 to 27 kg of Li-ion batteries.

Matt Roberds

Don't forget about the volume of the hydrogen tank. An LH2 tank is much
larger in volume than almost any other fuel.

Danny Deger

On Wed, 10 Jan 2007 15:39:17 -0000, Dylan Smith
> wrote in
>:

>On 2007-01-09, Larry Dighera > wrote:
>> Charge time for the Altair batteries is only a few minutes as I
>> recall.
>
>I'm extremely skeptical - if these batteries are not snake oil, consider
>this. Let's call "a few minutes" 10 minutes, and let's say the battery
>pack stores 70kWh (enough to run a motor producing 94 hp for 1 hour).
>
>To put 70kWh's worth into a battery pack in 10 minutes would require a
>charger capable of putting out 420kW.
>
>At 120 volts, 420kW would require a current of 3500 amps. Look at the
>massive thick wire coming into your house (which maybe is rated at 80
>amps).
>
>Now let's say these batteries give three hours worth at 70kWh, and
>charge in 10 minutes - now you're up to 10,500 amps at 120 volts. YOU
>CANNOT AVOID high voltage, high amperage controls in a vehicle like the
>Tesla, regardless of the battery technology. You are moving around
>tremendous amounts of current. If this mythical charger was 99%
>efficient, the 1% emitted as heat could heat an entire office building
>in the dead of winter in central Canada. To consider this new battery
>technology a silver bullet is to ignore the well established laws of
>physics. Now imagine if *everyone* is charging their mythical car. No
>practicable electricity distribution network that's feasable in the near
>term could cope.
>
>It would be totally and utterly impractical to charge these batteries at
>this rate. I'll let you do the calculations for the equivalent in
>electricity that filling a Cessna 150 with avgas in 4 minutes (the
>typical time to do it at a self serve pump) would be.


The issue of high charging current is true, of course.

After studying the information available on the Altair web site
<http://www.altairnano.com/markets_amps.html>, it has become apparent
that their battery technology trades energy density for low internal
resistance. So their product is probably not the best choice for
aircraft due to weight considerations.

On 10 Jan 2007 11:59:02 -0800, wrote in
om>:

>
>Larry Dighera wrote (rather quoted a comment from wired.com):
>> http://www.wired.com/news/wiredmag/0,71414-0.html?tw=rss.index
>> The Tesla as it stands is obsolete if it doesn't use the new type
>> batteries from Altair[**]. It will be the laughingstock of the
>> business world if it delivers its current overly-complicated
>> battery system, with its computers and sensors and HVAC system.
>
>Larry, just BTW, the Altair Nano batteries this guy is going on
>don't pass the sniff test very well...
>
>Tesla isn't using them because Tesla wants to ship cars
>sometime this decade.
>
>Altair claims that WRT conventional graphite electrode lithium-ion
>batteries, their TiO nano-granule electrode lithium-ion batteries
>have 3X the energy density, 60X the max charge rate, and 10X
>the charge-cycle lifetime.

I must have overlooked that "3X energy density" claim. I did see this
marketing claim however:

"Three times the power of existing batteries".

The way I read the chart on the Altair web site
<http://www.altairnano.com/markets_amps.html>, it looks like Altair's
product's Specific Energy (is that similar to energy density) is about
half of that of conventional LiIon cells.

>If these batteries actually existed in a form that would allow
>Tesla to ship 200 cars this year, you would think that every
>single cell phone and laptop in the universe would be running
>on them, wouldn't you? I mean, *I* want my cell phone charge
>to last 2 weeks instead of 5 days, *I* want to be able to charge
>my laptop in 1 minute, and then have it last through an entire
>8-hour flight, *I* want my cell phone battery to
>last longer than the phone instead of having to replace the
>battery after 18 months.

If you can trust The Motley Fool:
http://www.fool.com/investing/high-growth/2005/05/31/history-repeats-at-altair.aspx
it looks like it will be Toshiba delivering this technology.

>But yet I can't go to batteries.com and buy one of these
>wonderful batteries that Tesla is so stupid for not using.
>I think there *might* be a reason for that. :-)

Agreed.

>BTW, this press release:
>http://www.autobloggreen.com/2006/12/29/altair-nanotechnologies-ships-first-10-batteries-to-phoenix-moto/
>
>seems to indicate that Altair's entire production volume of batteries
>to date is 10 35kWh battery packs for $750,000. It apparently
>took 30 days (well, that includes Christmas) to deliver all 10 battery
>packs.
>
>I hope Altair and Phoenix are fabulously successful, but there is
>good reason for skepticism.
>
>-Jay-

So it would seem.

Recently, Larry Dighera > posted:

> On Wed, 10 Jan 2007 15:39:17 -0000, Dylan Smith
>>
>> It would be totally and utterly impractical to charge these
>> batteries at this rate. I'll let you do the calculations for the
>> equivalent in electricity that filling a Cessna 150 with avgas in 4
>> minutes (the typical time to do it at a self serve pump) would be.
>
> The issue of high charging current is true, of course.
>
> After studying the information available on the Altair web site
> <http://www.altairnano.com/markets_amps.html>, it has become apparent
> that their battery technology trades energy density for low internal
> resistance. So their product is probably not the best choice for
> aircraft due to weight considerations.
>
According to their W/kg chart, their batteries trade a lower specific
energy (W hr/kg) for a considerably higher specific power, but I would
think that Altair's operating temperature range would be a more important
factor w/r/t aviation, as the other batteries' performance suffers badly
in low-temperature environments. I doubt that a typical Li-ion battery
would deliver the indicated specific energy in aviation temperatures, so
any weight benefit would be compromised.

Neil

On 10 Jan 2007 12:59:43 -0800, "JD" > wrote in
. com>:

>Check out the batteries from A123 Systems:
>http://www.a123systems.com/html/technology.html
>
> Li Ion batteries made with iron at 1/5 the price, twice the power and
>half the weight of conventional Li Ions.
>They are already on the market and are starting to show up in
>DeWalt's/Bosch 36V cordless tools.
>They have a weight to Watt ratio less than 1 lb / 1500W ( .9 to be
>exact).

http://www.a123systems.com/html/_chart_popUps/techComp.html

Parameter A123 Ml LiIon
----------------------------------------------------------------
Power Density >3,000 W/Kg 1,350 W/Kg

Weight to discharge @ 1,500W 0.9 lbs 2.75 lbs

Life at 100% DoD >1,000 500

So what's the downside to this cell for aviation applications?

>Scheeesch if their stock ever goes public, I'll be standing in long
>line of buyers.

If this is true:

http://www.a123systems.com/html/tech/power.html
A123Systems M1 cells offer the highest commercially available
power density of any Li Ion chemistry: Our high power products are
able to pulse at discharge rates as high as 100C and deliver over
3000W/kg, over an order of magnitude better than conventional
Lithium-Ion cells and with their low impedance and thermally
conductive design, A123 cells can be continuously discharged to
100% depth of discharge at 35C rate, a marked improvement over all
other rechargeable battery alternatives.

I share your enthusiasm.

On Mon, 15 Jan 2007 14:31:16 GMT, "Neil Gould"
> wrote in
>:

>Recently, Larry Dighera > posted:
>
>> On Wed, 10 Jan 2007 15:39:17 -0000, Dylan Smith
>>>
>>> It would be totally and utterly impractical to charge these
>>> batteries at this rate. I'll let you do the calculations for the
>>> equivalent in electricity that filling a Cessna 150 with avgas in 4
>>> minutes (the typical time to do it at a self serve pump) would be.
>>
>> The issue of high charging current is true, of course.
>>
>> After studying the information available on the Altair web site
>> <http://www.altairnano.com/markets_amps.html>, it has become apparent
>> that their battery technology trades energy density for low internal
>> resistance. So their product is probably not the best choice for
>> aircraft due to weight considerations.
>>
>According to their W/kg chart, their batteries trade a lower specific
>energy (W hr/kg) for a considerably higher specific power, but I would
>think that Altair's operating temperature range would be a more important
>factor w/r/t aviation, as the other batteries' performance suffers badly
>in low-temperature environments. I doubt that a typical Li-ion battery
>would deliver the indicated specific energy in aviation temperatures, so
>any weight benefit would be compromised.
>
Battery temperature is important. However it's important to realize
that batteries with a higher internal resistance will generate more
heat under load than those with lower internal resistance, so I doubt
low temperature would be an issue with conventional LiIon batteries.
In fact, the Tesla car needs a liquid cooling system to remove battery
heat, and I would suspect that some sort of cooling system would be
required for aviation applications also.

If it is the weight of the batteries that preclude the use of electric
power for airplane use, using the Altair batteries, with half the
energy density of conventional LiIon cells, wouldn't make very good
sense. The A123Systems M1 cells, with their claimed "the highest
commercially available power density of any Li Ion chemistry" may be
an enabling technology for electrically powered airplanes:
http://www.a123systems.com/html/home.html

On Thu, 11 Jan 2007 01:10:23 GMT, David CL Francis
> wrote in
>:

>On Tue, 9 Jan 2007 at 14:38:16 in message
>, Larry Dighera
> wrote:
>
>>http://www.teslamotors.com/
>
>Interesting. I see Vauxhall in the UK have just launched a similar car.
>
>Environmentally they do not produce much pollution on the road but, of
>course, where they do create it is at the providing power station

I believe the efficiency of commercial electric generating power
stations and electrical motors is far superior to that of internal
combustion Otto Cycle engines ~38%.

>(except for Nuclear of course).

The jury is still out on Nuclear. It is relatively clean during
normal operation, but one Chernobyl incident pollutes vast amounts
land (and air) for centuries. And then there's the waste disposal
issue....

>I am prejudiced - I have just purchased a Toyota Prius! Nothing like as
>sporty of course!

And considerably less expensive than the Tesla Motors car by a factor
of four or so.

>Batteries will have to have a very great capacity for their weight to
>make a normal aircraft successful.

That seems to be the reality. It is because battery energy must be
expended to support the aircraft as well as propel it, except for
lighter than air airships and balloons.

Larry Dighera > wrote:

> I would think that the LiIon cells could be made lighter if
> specifically designed for aviation use. Currently they are steel
> jacketed AA sized. Steel might be replaced with Titanium (atomic
> number 22). Lithium (atomic number 3) is a light metal as is the
> carbon (atomic number 6) anode.

The problem is not how the chemicals are contained, the problem is the
weight of the chemicals themselves. There could be some minor
improvement in the overall weight of the batteries, but not enough to
overtake the high energy density of liquid fuels.

> You seem to have a firm grasp of the issue. Given:
>
> http://en.wikipedia.org/wiki/Lithium_ion_battery
> Lithium ion battery
> Specific energy density: 150 to 200 W·h/kg (540 to 720 kJ/kg)
> Volumetric energy density: 250 to 530 W·h/L (900 to 1900 J/cm3)
> Specific power density: 300 to 1500 W/kg (@ 20 seconds [2] and 285
> W·h/L)
>
>
> http://en.wikipedia.org/wiki/Gasoline
> Gasoline
> Energy content
> Fuel type Megajoules/L MJ/kg BTU/US gal
> Premium Gasoline 32.84 43.50 131,200
>
> Can you quantify the prospect of replacing Avgas with LiIon batteries?

The key comparison is the specific energy density, since that would tell
you how far you could fly, and with what load. If batteries are going to
be competitive, they would have to have a weigh about the same as the
liquid fuel to be competitive in aviation use. Otherwise, either useful
load would drop, the range would be limited, or the aircraft would be
completely impractical.

To end up with a similar weight, they would need similar energy
densities, multiplied by the efficiency of the prime mover.

From the table provided above, the energy density of gasoline is 45
MJ/kg, and lithium batteries are 0.72, at best. A gasoline engine is
perhaps 25% efficient in an aircraft, and an electric motor, with its
control, would be about 90% efficient.

Multiplying the two to get the required useable energy density gives:
For gasoline engines: 43.5 X 0.25 = 10.88 MJ/kg
For batteries: 0.72 X 0.9 = 0.65 MJ/kg

Therefore, you would need a battery pack that weighed about 15 times as
much as the gasoline fuel and tank to be able to perform the same amount
of work. That isn't even close.

Given the huge difference in weight, the prospect of using lithium ion
batteries to power conventional aircraft is almost nil. Battery
designers don't need a breakthrough, they would need a miracle to get the
energy density to a point where it would be competitive with liquid fuel.

Larry Dighera > wrote:

> If it is the weight of the batteries that preclude the use of electric
> power for airplane use, using the Altair batteries, with half the
> energy density of conventional LiIon cells, wouldn't make very good
> sense. The A123Systems M1 cells, with their claimed "the highest
> commercially available power density of any Li Ion chemistry" may be
> an enabling technology for electrically powered airplanes:
> http://www.a123systems.com/html/home.html

Power density isn't the issue. That only means they can dump the energy
contained in the battery faster than other types. Their batteries would be
useful where you need high power for short bursts of time, like hand-held
drills, or photo flash units. Power density says nothing about how much
energy is contained in the battery.

The important measure for aircraft application is energy density. The A123
batteries have about 1/2 the energy density of current LiIon batteries,
which means you would need a battery that weighed twice as much as other
types of LiIon batteries. This is moving the wrong way, if they are to be
practical in aircraft application.

Larry Dighera > wrote:

> On 10 Jan 2007 12:59:43 -0800, "JD" > wrote:
>
>> Check out the batteries from A123 Systems:
>> http://www.a123systems.com/html/technology.html
>>
>> Li Ion batteries made with iron at 1/5 the price, twice the power
>> and half the weight of conventional Li Ions. They are already on the
>> market and are starting to show up in DeWalt's/Bosch 36V cordless
>> tools. They have a weight to Watt ratio less than 1 lb / 1500W ( .9
>> to be exact).
>
> http://www.a123systems.com/html/_chart_popUps/techComp.html
>
> Parameter A123 Ml LiIon
> ----------------------------------------------------------------
> Power Density >3,000 W/Kg 1,350 W/Kg
>
> Weight to discharge @ 1,500W 0.9 lbs 2.75 lbs
>
> Life at 100% DoD >1,000 500
>
> So what's the downside to this cell for aviation applications?

The downside is that their energy density is something like 110 W-Hr/kg,
which is lower than other types of LiIon batteries, with can be as high
as 350. That means to get the same endurance, you would need twice the
weight of A123 batteries. Weight is the major issue with aviation
applications, so these batteries are heading the wrong way.

Larry Dighera > wrote:
>
> Here's another link to information about GM's 'Volt prototype hybrid
> automobile dated Jan. 7, 2007.
>
>
> http://www.canada.com/topics/finance/story.html?id=4adec548-a654-4000-8
> b3c-aff0354600aa&k=45978&p=2
> Lutz said the engineering development of the car itself is 18
> months from being completed. The batteries are about 18 months
> behind the rest of the car.
>
> How many years would that put GM's product behind the Japanese? :-(

None.

All of the car manufacturers are waiting for battery technology to get to
the point where such cars can be practical. The auto manufacturers have
put electric cars on the market in the past, mainly because of
California's ZEV requirements, but they were quickly pulled when the
California regulations were retracted, since the vehicles were expensive
and the batteries had relatively short lives. Battery technology at the
time wasn't good enough to make the vehicles practical.

Battery technology has improved somewhat since then, with about double
the energy density, but they still have a long way to go before they can
compete with liquid fuels foe convenience and cost.

This is like the days when stereo equipment manufacturers were in an
ouput power race, or today's speed race with personal computer
manufacturers. Every time a new improved type of transistor came on the
market, or a new microprocessor, the builders of the final product would
quickly market the highest power stereo, or the fastest computer. They
were all pretty well at the same place in the market at the same time,
based on what was available.

The same can be said for hybrid vehicles, plug in hybrids, or all-
electric vehicles. The manufacturers need appropriate batteries to make
their products practical and cost-effective.

As far as practical aviation applications, using batteries for primary
power is nowhere near possible today, and given the huge gulf in weight
that has to be overcome, they will only be practical after a huge
technical breakthrough, making the energy density something like ten or
fifteen times what it is today. At the present rate of improvement,
assuming it can be sustained, that will take something like 50 years.

The original developer of LiIon batteries has stated that such
improvements will never happen. He feels that improvements of existing
batteries will be in safety, cost, and the ability to more quickly charge
or discharge them, but there will be little improvement in energy
density, which is what would be required for aviation application.