On Mon, 05 May 2008 12:57:36 -0600, Bill Daniels wrote:

It seems that every day now some electronics giant is announcing their
micro fuel cell.
See:
http://www.goodcleantech.com/2008/05...ybrid_fuel.php

What I want to know is whether these things have a place in gliders.
The first concern that pops into my head is that they must depend on
atmospheric oxygen which might not be enough at high alititudes.
Anybody know?

I suppose you could always use an (electrically driven) supercharger if
that is a problem. However, as Aerovironment were planning to use a fuel
cell in their electric flying wing, which operates at 80,000 ft, I suppose
the problem, if it is one, is solvable.

The more relevant questions concern the energy density of a fuel cell plus
supply tank and its energy efficiency. I've not seen anything about energy
density, but its efficiency over a charge/discharge cycle is far below
Li-poly batteries - something like 66% vs 85%, which makes it less
attractive for a solar powered 'eternal airplane' than Li-poly cells.

If you're talking about using it to fly a ground-charged SLMG, then the
energy density would be the critical factor. You probably wouldn't want to
use a hydrogen fuel cell because the energy density of a tank of hydrogen
is rather low.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot