Electrically Powered Ultralight Aircraft

In rec.aviation.piloting Gig 601XL Builder wrDOTgiaconaATsuddenlink.net wrote:
Gattman wrote:
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in message
...

Do me a favor Gattman. What is the weight of the most effeicent
battery that could power an automobile at highway speed and how long
will it do so and how long to recharge?

Well, if I tried to answer that I'd sound like mx. I don't know
what the "most efficient" battery is for that purpose. It's a hell
of a lot heavier than the 250-250 pound machines I worked with. I
think 4-6 SLAs--possibly the least efficient--would pull a vehicle,
but I doubt it would make highway speed and if if it did it wouldn't
be for more than a few minutes. Charge time for each battery would
probably be a couple of hours, maybe longer.
I bet it would weigh a hell of a lot more than a Rotax. Internal
combustion is still the most bang for the buck this side of nuclear.

I think the most realistic use of an electric motor in an aircraft
would be in the context of something like a glider, for maintaining
altitude or finding a thermal or just getting home. It would be fun
to fly an ultralight around the pattern under electrical power, but I
wouldn't stray very far.

-c


I understand and thank you for not MXing us. But the point isn't the weight
of the battery as compaired to a Rotax or any other engine. The issue I had
been getting at is the weight of the battery in comparison to the weight of
full load of gasoline.

Let's take my 601XL. 2 aluminum 12 gallon tanks each tank ways let's say 10
pounds add in 145 lbs of fuel and you have 165 pounds of transportable
energy that will produce ~100HP for about 4 hours.

My question to anyone is what is the lightest battery that is capable of
powering any motor that will produce the equivilent power for and equal
amount of time?

If you go to http://xtronics.com/reference/energy_density.htm you find
the energy densities of a lot of things.


Propane (liquid) 13,900 Wh/kg
Diesel 13,762 Wh/kg
gasoline 12,200 Wh/kg
Ethanol 7,850 Wh/kg
Methanol 6,400 Wh/kg
Secondary Lithium - ion Polymer 130 - 1200 Wh/kg
Primary Zinc-Air 300 Wh/kg
Lead Acid Battery 25 Wh/kg

So batteries have to improve by a factor of 10 to match gasoline.




--
Jim Pennino

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