Re: Silent Flight; Fuel Cells Are the ONLY Solution

On 30 Dec 2005 18:05:57 -0800, "Bret Cahill"
<BretCahill@xxxxxxx> wrote:

>For the max 66.7% propulsion efficiency blimps/airships need to move a
>LOT of air at only TWICE the craft speed [read: very slow ~ 40 mph]
>which means big slow moving quiet props.
>
>It would be sooo much fun to silently drift up a canyon. The loudest
>noise would be your own breathing.
>
>The mule deer or cougar would, of course, be startled by the shadow but
>not before you got some good video.
>
>
>Bret Cahill
>

IIRC, the military had Schwizer add a well muffled aircraft
engine and prop to a 2-32 glider airframe back during Viet
Nam. It was apparently pretty sneaky, at least
acoustically.

Regards,

Bill Ward
.

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