Can Aircraft Be Far Behind?

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.