Doug,

I was about to give you a "gold star" but then found some more
misconceptions.

There is gravity in outer space. Anywhere there is matter, with mass,
there is Gravity. The moon is held in orbit by the earth's gravity.
Earth in solar orbit, etc.

Lift would be possible without gravity, (if it was possible to have no
gravity.) If you placed an airplane in air, but no gravity, and provided
a propelling force (engine), the wing could certainly produce lift without
gravity . Without gravity, lift would be unbalanced, resulting in your
aircraft doing successive loops!

Air (or other "fluid" if we are taking this into outer space), is needed
to provide lift. But the forces involved in gliding flight are still
three.....lift, drag, and gravity.

Although thought provoking exerceses, better to say "what is" than
"what if.".....

Cookie





At 01:39 20 March 2009, Doug Hoffman wrote:
Bob Cook wrote:

If we are gonna play what if.....

What if there was no lift? (like a brick,)

Sure it would move because of gravity, but in what direction? Down!
Not
forward!

That is correct and demonstrates a useful "thought exercise".


So tell me again how gravity imparts a forward force to a glider?

By itself it cannot. The presence of gravity *and* air are required for

gliding (forward) motion.


Although "no gravity is not possible,

Sure it is. Place your glider in outer space. Likely? No. Possible?
Certainly.


"no lift" is easily demonstrated:

And lift(as we are using the term) without gravity is not possible.

Regards,

-Doug