# Re: will aircars destroy the auto industry?

From: Spike Jones (spike66@ibm.net)
Date: Sun Apr 30 2000 - 00:39:24 MDT

> > Mike, that 20 MPG number is a fantasy bud. Otherwise
> > its back to aerodynamics 101 for me. {8^D spike
>
> GBurch1@aol.com wrote:
> I don't have Spike's technical prowess in aerodymanics (althoughI know
> they're great - someone who has the sense of flight at Mach 20 is my hero),
> but to this stick-and-rudder guy, the Moller Aircar "just don't look right".

WOW! Thanks Greg, I gotta reply to THAT comment just to see
it on my CTR again! {8^D

The reason Im having difficulties with Moller's aircar is a neat
little estimating technique for the thrust required to maintain straight-
and-level flight: you need to know the power-off glide ratio. If it is
10 forward to 1 down, then it takes a thrust of about 1/10 the weight
of the aircraft to fly at the power-off glide speed.

The Moller aircar looks like it would power-off glide like a set of
car keys. What is that little airfoil way back aft for? Just to look
cool? Glide ratio 10 down for every one forward? In any case, it looks
like you would need to be making power at *almost* the vertical
takeoff rate just to fly straight and level, and with the numbers they
call out on the website, with those little tiny rotors, the straight and
level power requirement looks like in the neighborhood of 800 hp.
Recall that a typical modern Detroit mobile, ambling down the
freeway at 100 kph only requires about 30 hp, if I may mix units.

Nowthen, if we want to theorize a really high horizontal speed
associated with that 800 hp, we are up against the drag-as-square-
of-velocity problem, and so we still have a voracious fuel appetite.
Perhaps Doug Jones will weigh in on this, hes more aerominded than
I am.

I am uncomfortable being in the nay-sayer position, dont like
doing that. But the Moller aircar as shown on the website
wont fly in that configuration. spike

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