Soaring on Mars

Given the lesser density of air on Mars what would be the glide ratio of
a PW-5 starting at an altitude of say 5000 feet? (lesser gravity, too)
Is it worth book a trip in next few years?

In article , puffnfresh
wrote:

| Given the lesser density of air on Mars what would be the glide ratio of
| a PW-5 starting at an altitude of say 5000 feet? (lesser gravity, too)
| Is it worth book a trip in next few years?

The X-Plane flight simulator has an option of flying on Mars,
implementing the correct gravity, air density, etc. Air is about 1% as
dense as on Earth, with 1/3 the gravity. I was able to start the
included SH-Cirrus sailplane at about 20000' AGL and dive it to get
enough airspeed to sort of glide, but IAS never got above 40 knots, even
though groundspeed was scary fast. Landing would be a *big* problem...

-- Tim Olson

"puffnfresh" wrote in message
...
| Given the lesser density of air on Mars what would be the
glide ratio of
| a PW-5 starting at an altitude of say 5000 feet? (lesser
gravity, too)
| Is it worth book a trip in next few years?

My first impression is that since both Lift and Drag include
density in the same way:
Lift = Cl x 1/2 x rho x v x v
Drag = Cd x 1/2 x rho x v x v
The ratio is independent of density.
However, you would have to fly very fast (large v) to
generate even 1/3 of the weight on earth, and the poor
glider would probably flutter to bits.
You would then need a *huge* parachute to get you down in
one piece.
I think you could put your money to better us !!
John G.

Said another way, the air is so thin on Mars, you might as well be trying to
soar on the moon. It doesn't matter that the gravity is less; without air,
you're going to have a 0:1 glide ratio!

Chris




"puffnfresh" wrote in message
...
Given the lesser density of air on Mars what would be the glide ratio of
a PW-5 starting at an altitude of say 5000 feet? (lesser gravity, too)
Is it worth book a trip in next few years?

"C.Fleming" wrote:

Said another way, the air is so thin on Mars, you might as well be trying to
soar on the moon. It doesn't matter that the gravity is less; without air,
you're going to have a 0:1 glide ratio!


I would rather think the opposite. As long as you have air, even with low
density, you keep the same glide ratio, but at a higher speed. A higher
speed is closer to satellisation speed, i.e the contribution of the centrifugal
force due to the curvature of the ground is higher, so the glide ratio
should be a little higher. But this is only true provided the increased best glide
speed remains under the speed of sound, which is unlikely, near or above this
speed aerodynamics changes completely and glide ratio becomes very low.

I have just been to a presentation on the Perlan project which at it second
stage goal of 100,000ft height is
about mars ground level air pressure.
The aircraft would have 29-30 metre wings (ETA size) and be designed to fly
in the range of 0.6-0.7 mach .The convergence into "coffin corner" occurs at
108,000ft .
The l/d of the design at sealevel would be 50:1 and at the altitude would
drop to 25:1 (source, Nasa supercomputer flight simulations)
The designer of the ETA has been asked to provide some data on large span
composite wing structures at the reynolds numbers required for this project
gary
"C.Fleming" wrote in message
...
Said another way, the air is so thin on Mars, you might as well be trying
to
soar on the moon. It doesn't matter that the gravity is less; without
air,
you're going to have a 0:1 glide ratio!

Chris




"puffnfresh" wrote in message
...
Given the lesser density of air on Mars what would be the glide ratio of
a PW-5 starting at an altitude of say 5000 feet? (lesser gravity, too)
Is it worth book a trip in next few years?