Nice work Bob, If I might relate this to aircraft though, I do NOT
believe you can make a similar arguement. The problem that would
rear it's ugly head is the prop disk. On most powered aircraft the
highest drag component is the propeller in decent.( A shallow decent
not a intentional dive!) Unlike a car where you can literally "put
it in neutral" most aircraft don't have a clutch or transmission.
Indeed even if they did you would have to have a prop that would
fully feather to take advantage of the "downhill" portion of the run
while the engine idled. A practical example of this was printed in
the Van's newsletter. There was a US Representitve or Senator,
(possibly state) flying his own aircraft.(I already like the guy) He
had a failure of his prop extension or the bolts. The prop
completely parted from the plane and fortunately didn't damage
anything else while doing so. He (sorry I can't remember his name)
declared an emergency and was closest to Truckee CA airport. Using
his GPS's pre-programed glide range indication he informed the
Airport that he would probably be about 2 miles short. The glide
range had been very accurate when practicing engineout procedures
previously. The short story is that he made the airport EASILY.
Talking to Van later he was told, "Sure the plane makes a MUCH
better glider without the propeller" I'm sure Vance can verify this
as well. If you have to prove this to yourself go up in anything
with a constant speed. Idle the engine and set best glide in corse
pitch. Then set the prop to flat pitch and you will think you just
threw out an anchor! (be careful not to stall)! Bill Jepson

Hi Bill,

I agree.  The only time you would get any benefit at all from climing
then gliding is when the engine is running ineffeciently when level.
I'm pretty sure I remember a comment in the last few weeks about the
benefit of a constant speed prop being that the load can be adjusted to
operate at a good bsfc.

I and one of my more adventurous flight instructors killed the engine on
a C150 once.  I was supprised that the prop didn't windmill.  It
stopped.  We had to dive to about 120 or so to get it to move, then the
engine started immediately.

The Senator was lucky.  Often loosing a prop throws the CG off enough to
create handling problems.  I would be concerned about slowing down with
the CG too far aft.

Bob White

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