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Old November 4th 14, 06:05 PM posted to rec.aviation.piloting,sci.chem.electrochem.battery
Larry Dighera
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Default Electric Trainer: $5 An Hour Flight

On Mon, 03 Nov 2014 19:45:30 GMT, Skywise wrote:

Larry Dighera wrote in
:

at an energy cost of about $1 an hour.


I call ********.

Per wikipedia article on the Cessna 172, the Lycoming IO-360-L2A
engine produces 120kW of power.

Per,
http://www.eia.gov/electricity/month...m?t=epmt_5_6_a

the average cost of electricity across all sectors for August 2014 in
the United States was 10.92 cents/kilowatt.

Assuming no conversion losses and 100% efficiency, that's 120kW/hr
times 10.92 cents/kW = $13.104 worth of electricity per hour.

I may not be comparing my apples to the oranges properly, though.
I gladly accept critique. But their statement just smells fishy.

Brian


Interesting. Thank you for your astute analysis.

If I recall correctly, the article mentioned the wings being clad in
photovoltaic solar arrays, so if the aircraft were tied-down outside,
conceivably it might recharge its internal battery pack without purchasing
utility power. Of course, another consideration is amortization of battery
replacement costs expressed on an hourly basis. But that may be more analogous
to Time Between Overhaul for IC powerplant.

The article
http://www.avweb.com/avwebflash/news/Electric-Trainer-5-An-Hour-Flight223010-1.html
mentioned:

"... new battery chemistries from Panasonic that he said are expected to
deliver power densities of up 250 watts/kg, compared to about 160 watts/kg
that are typical for the best contemporary production batteries."

I searched for Panasonic batteries that might meet the specification mentioned
in the article, but was unsuccessful. Perhaps a crosspost to
sci.chem.electrochem.battery may shed some more light on the claim.

All this aside, producing a certified electrically powered aircraft would truly
be a significant and laudable milestone. Hopefully it will at least prove the
feasibility of an electric powerplant to reliably, quietly and efficiently
compete with IC powerplants.

As Jim P. and I discussed many years ago, it is difficult to store electricity.
It can be done chemically with batteries, or kinetically by pumping water to an
elevated vessel. The first lacks the energy density to compete with petroleum;
the latter is impractical for flight. :-) However generating the electric
power on-board opens the door to the possible use of hydrogen powered fuel-cell
technology. AIR when researching years ago, hydrogen compressed to about
10,000 lbs/sq in was roughly comparable to the energy density of gasoline. At
the Consumer Electronics Show earlier this year, I was told by an engineer with
one of the automotive firms displaying concept cars, that they had successfully
increased fuel-cell efficiency to ~60%. If true, this would be an enabling
breakthrough for electrically powered vehicles. My previous research indicated
that fuel-cell efficiency was about 30% at that time.

I'm forever confusing these two terms:

* Power density (or volume power density or volume specific power) is the
amount of power (time rate of energy transfer) per unit volume.

* Energy density is the amount of energy stored in a given system or region
of space per unit volume or mass