Electric Trainer: $5 An Hour Flight

[Larry Dighera]

<http://www.avweb.com/avwebflash/news/Electric-Trainer-5-An-Hour-Flight223010-1.html>
Electric Trainer: $5 An Hour Flight

While electric aircraft have gotten plenty of gee-whiz press coverage, they
lack one thing: credible production airplanes. At Redbird's Migration training
conference this week, Aero Electric Aircraft Corp.'s George Bye pledged to
change that by showing up at next year's event with a prototype of the Sun
Flyer, a two-place electric that may become the first certified
electric-powered trainer.

At a short talk at Migration, Bye told the audience that the Sun Flyer
represents a synthesis of several technologies, including improved DC motors,
higher-capacity batteries, materials technology and the ability to tweak
airframe and propeller aerodynamics to reduce drag and extend flight duration,
which remains the unaddressed weakness of electric aircraft. However, Bye
insists that improving battery technology will address this, specifically 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.

That will give the Sun Flyer a flight endurance of about four hours or a
practical training time of about three hours at an energy cost of about $1 an
hour. In addition to quick-change battery packs, the Sun Flyer will also be
equipped with wing-mounted solar cells that generate about 15 to 20 percent of
the aircraft's low-speed cruise power requirement, thus extending its range.

Bye said Aero Electric has heard complaints about light sport aircraft lacking
the durability to withstand the rigors of training so the company will produce
a certified aircraft. "This is not an LSA and we don't want it to appear to
have those challenges," he said. What about the regulatory challenge? Bye said
the company has mapped out a two-year certification program with the FAA which,
conceptually, has revealed no showstoppers.

"If we can do that, we've got a solution. If this is real, we've got a
solution," Bye said. Cost-wise, Bye's data showed that proposed all-in direct
costs for the Sun Flyer, including battery replacement costs, will be about
$4.65 an hour, compared to $73 for a gasoline-powered Cessna 172.

[george152]

On 03/11/14 06:36, Larry Dighera wrote:

> "If we can do that, we've got a solution. If this is real, we've got a
> solution," Bye said. Cost-wise, Bye's data showed that proposed all-in direct
> costs for the Sun Flyer, including battery replacement costs, will be about
> $4.65 an hour, compared to $73 for a gasoline-powered Cessna 172.
>
>
>
>
Where do we sign up :)

[Skywise]

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/monthly/epm_table_grapher.cfm?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
--
http://www.earthwaves.org/forum/index.php - Earth Sciences discussion
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?

[Larry Dighera]

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/monthly/epm_table_grapher.cfm?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

[Skywise]

Larry Dighera > wrote in
:

> 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.

Some more back-of-the-envelope calculations, disgregarding losses
and efficiency concerns.

Maximum insolation on the Earth's surface is about 1kW per square
meter.

According to wikipedia, a Cessna 172's wing area is 16.2 square meters.

According to a graph on the wikipedia article on solar cell efficiency
the most efficient cell ever developed is 44.7%.

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

OK...

16.2 square meters times 1kW per square meter is 16.2 kilowatts.
Multiplied by 44.7% leaves 7.2414 kilowatts.

Even if you had 10 hours of ideal sunlight, you'd only get a
total of 72 kilowatt/hours of energy.

From my previous post of the Cessna 172's engine putting out 120kW
of power, 10 hours of charging would only get you 36 minutes of
flight. Lower power settings of course extends that, but recall I'm
neglecting all the forms of losses.

Don't get me wrong. I'm not saying the venture is not a good idea
and I'm not trying to knock it down. But there's reality and then
there's marketting hype.

As Scotty was fond of sayin', "Ye canna break the laws of physics,
Cap'n!"

Brian
--
http://www.earthwaves.org/forum/index.php - Earth Sciences discussion
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?

[[email protected]]

In rec.aviation.piloting Skywise > wrote:
> Larry Dighera > wrote in
> :
>
>> 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.
>
> Some more back-of-the-envelope calculations, disgregarding losses
> and efficiency concerns.
>
> Maximum insolation on the Earth's surface is about 1kW per square
> meter.
>
> According to wikipedia, a Cessna 172's wing area is 16.2 square meters.
>
> According to a graph on the wikipedia article on solar cell efficiency
> the most efficient cell ever developed is 44.7%.
>
> http://en.wikipedia.org/wiki/Solar_cell_efficiency
>
> OK...
>
> 16.2 square meters times 1kW per square meter is 16.2 kilowatts.
> Multiplied by 44.7% leaves 7.2414 kilowatts.
>
> Even if you had 10 hours of ideal sunlight, you'd only get a
> total of 72 kilowatt/hours of energy.

You have to multiply that by the sine of the angle of the photocell
to the Sun. For a horizontal flat plate at noon, the latitude is
pretty close. Early morning and late after noon the angle is approaching
zero degrees.

Here's a website with calculators.


> From my previous post of the Cessna 172's engine putting out 120kW
> of power, 10 hours of charging would only get you 36 minutes of
> flight. Lower power settings of course extends that, but recall I'm
> neglecting all the forms of losses.
>
> Don't get me wrong. I'm not saying the venture is not a good idea
> and I'm not trying to knock it down. But there's reality and then
> there's marketting hype.
>
> As Scotty was fond of sayin', "Ye canna break the laws of physics,
> Cap'n!"
>
> Brian

--
Jim Pennino

[Skywise]

wrote in :

> In rec.aviation.piloting Skywise > wrote:
>> Even if you had 10 hours of ideal sunlight, you'd only get a
>> total of 72 kilowatt/hours of energy.
>
> You have to multiply that by the sine of the angle of the photocell
> to the Sun.

True. But I did say....

>> but recall I'm neglecting all the forms of losses.

Brian
--
http://www.earthwaves.org/forum/index.php - Earth Sciences discussion
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Sed quis custodiet ipsos Custodes?

[[email protected]]

In rec.aviation.piloting Skywise > wrote:
> wrote in :
>
>> In rec.aviation.piloting Skywise > wrote:
>>> Even if you had 10 hours of ideal sunlight, you'd only get a
>>> total of 72 kilowatt/hours of energy.
>>
>> You have to multiply that by the sine of the angle of the photocell
>> to the Sun.
>
> True. But I did say....
>
>>> but recall I'm neglecting all the forms of losses.
>
> Brian

Yeah, I know, but this is a big sore point for me.

There is a huge difference between the power available at Noon and the
power available during the day for a fixed cell.


--
Jim Pennino

[Vaughn]

On 11/5/2014 1:18 PM, wrote:
> There is a huge difference between the power available at Noon and the
> power available during the day for a fixed cell.
I live in sunny south Florida, but I'm still waiting for the day that I
see full manufacturer's rated power output from a solar panel. For that
to happen, you would theoretically need a perfectly clean panel pointed
directly at a full sun, at some specific temperature, and connected to a
specific load that perfectly matches the panel's impedance. ...And
probably not even then!

[John Henderson]

Vaughn wrote:

> I live in sunny south Florida, but I'm still waiting for the day that I
> see full manufacturer's rated power output from a solar panel. For that
> to happen, you would theoretically need a perfectly clean panel pointed
> directly at a full sun, at some specific temperature, and connected to a
> specific load that perfectly matches the panel's impedance. ...And
> probably not even then!

There's your problem - a cloudless sky.

My solar panels put out considerably more power when the sun shines
through broken cumulus cloud.

There's actually a lot more light available in that situation (direct
sunlight plus reflection from sunlit cloud).

John