"root" wrote in message
...

And also that the same glider on Mars has to fly 10 times faster in
order to obtain the same lift, balancing the same weight. But due to
the lower gravity on Mars, its weight would be lower, so the normal
(best L/D) speed on Mars would be less than 10 times this speed on the
earth. This speed can further be reduced by reducing the wing loading,
which provides some benefits on the earth that are no more valuable on
Mars, like speed, which is rather to high, and penetration, which makes
little sense. So it is not unbelievable that soaring may happen on Mars
at speeds between mach 0.5 and 0.7.

Most of that sounds ok -- except your guess at mach speeds. Where do you
come up with 0.5 to 0.7 mach? Remember that as air density decreases, so
does the indicated airspeed at which we reach 1.0 mach. From memory (of
many hours staring at airspeed/mach indicators), on Earth: 340 knots ias =
0.8 mach at approx. 28,000 ft., while at 39,000 ft., the ias drops to 260
knots while maintaining 0.8 mach. On Mars, with an air density of less than
1% of Earth's, it appears clear to me that because mach 1.0 will be reached
at a very low indicated airspeed, a conventional glider (the original post
referenced a PW-5) wouldn't have a chance.

On a lighter note: what a view of Mars! I live in Manhattan, and even with
a clear sky, we rarely can see more than the moon. But Mars is there for
anyone who chooses to look up! While crossing the North Atlantic, Mars is
so bright, you almost need to wear sunglasses as it comes over the eastern
horizon! Some flight attendants refused to believe me that it was Mars,
they thought it was another airplane!

-Chris