Boeing Fuel Cell Plane Flies At Last!

On Apr 10, 10:52 pm, Bruce wrote:
Weight and size. (you did ask)

I did. :-)

Weight: Hopefully Cui's battery improvements (or some similar change)
will alleviate the need to carry many pounds of batteries.

Size: Have you seen how small a powerful brushless electric motor is
these days? The prop has a large dimension in one direction; but at
least it can lie parallel to the mast and not take up much total
volume. I'm surprised there hasn't been more work on a ducted fan
solution - maybe the blades would just have to be too short to be
efficient, and still fit inside the aft fuselage... *shrug*

Take care,

--Noel

Hi Noel

This has exercised my little brain for some time.
The brushless DC motor is a perfect motive unit. Small, relatively light, simple
and reliable, and its performance is perfect for the job. It produces almost
flat torque, and will swing an efficient propeller with the same torque at the
high density altitudes I fly at.
The batteries are getting smaal enough that it could be done - Existing
improvements like the A123 Lithium batteries are not only safe but have much
better energy densities.
However - the batteries size comes with shape constraints as well, whereas you
can put that smelly dino stuff into just about any shape you want.
And the other part is also a problem, the propeller demands a large hole in the
structural strength determining skin of the boom. So you need to add lots of
heavy strengthening as well as doors etc.

If I ever work out how to do it and stay under the "non-lifting" limits my Std
Cirrus will be an experimental self launcher...

Bruce

noel.wade wrote:
On Apr 10, 10:52 pm, Bruce wrote:
Weight and size. (you did ask)

I did. :-)

Weight: Hopefully Cui's battery improvements (or some similar change)
will alleviate the need to carry many pounds of batteries.

Size: Have you seen how small a powerful brushless electric motor is
these days? The prop has a large dimension in one direction; but at
least it can lie parallel to the mast and not take up much total
volume. I'm surprised there hasn't been more work on a ducted fan
solution - maybe the blades would just have to be too short to be
efficient, and still fit inside the aft fuselage... *shrug*

Take care,

--Noel