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Re: [GZG][FH] Planet types (was Re: Locations of Stars)

From: Adrian Johnson <ajohnson@i...>
Date: Mon, 30 Nov 1998 16:28:25 -0500
Subject: Re: [GZG][FH] Planet types (was Re: Locations of Stars)


>> 3) Planets with thick atmosphere.
>>	I assumed that a fan or prop in a thick atmosphere would be
moving a
>> greater amount of air for a give amount of power
>pass! i really have no idea here; i could well be wrong.

You have VTOL's gaining 5" of movement.  Yes, fans/props would be moving
more air, for a given rpm, but would need more power to maintain that
compared with the lower pressure atmosphere.  With higher air density
come much higher aerodynamic drag.  Planes move slower at lower altitude
for a given power setting - that's why the Concorde flys up at 50,000
 Same with military aircraft - it costs them HUGE in fuel to go past
Mach 1
at low altitudes, they can suffer overheating problems on the leading
of wings and other bits, etc.  If you increase pressure beyond Terran
level standard, you'd have all kinds of odd effects - like the speed of
sound slowing down which would mean you'd run into supersonic shockwave
problems at lower absolute velocities, etc etc.  I'd tend to think that
with a thicker atmosphere, your VTOL's will
a) perform better in the low speed/hovering regime
b) consume more fuel doing it
c) not be able to achieve maximum velocities as high as they could in a
lower pressure atmosphere - though if your VTOL's are slow vehicles
(analagous to present day helicopters relative to the other types of
vehicles) it might not make any difference.
d) you might see an increase in their maximum carrying capacity - though
this does get limited by the aircraft's structural strength during
(often planes take off with more weight than they can land with without
collapsing their landing gear or causing other structural damage -
one of the reasons pilots dump fuel in an emergency)

Grav vehicles would see a decrease in their maximum speeds at low
- or at least would use more power and get hotter achieving them...

As to GEV's - I think the same sort of effect would happen... they'd be
able to carry more weight overall, but might use more fuel to do it. 
not sure about the pop-up thing, though...

Anyway - just some thoughts, which could be completely wrong.  In days
by, I was an amateur pilot, not an aeronautical engineer /


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