Frans,
Our postings are crossing a little, but I think the below covers also your
last one:
>
> How does an autogyro (autocopter?) work? What is causing the blades to
> move forward?
>
See http://en.wikipedia.org/wiki/Autogiro
> > A glider is
> > "propelled" by the forward - in the direction of flight - component of
> > the aircraft's WEIGHT only.
>
> Ok, got it. But without wings (but still with the majority of the
> weight) will the glider still be propelled forwards? I guess not.
Again: What is meant by "forward"? Without wings, the glider will still be
propelled forwards, and still by gravitational force. Unfortunately for the
pilot, however, "forward" now means more or less vertical towards the ground
..........
> Then what exactly is exercising a forward pulling force on the glider's
> fuselage? The fuselage has only drag. So something must be pulling it
> forward.
>
I may be stating the obvious, but a glider is always going down, or rather
gliding down - down relative to the air mass through which it moves. If the
air mass is moving upwards (thermals) faster than the glider moves downwards
through that air mass, the glider climbs relative to the ground even though
it goes down relative to the air mass. All the time, it is the gravity that
causes it to move, and movement through the air creates lift (if the wings
are still on), so that the glider does not fall like a stone through the
surrounding air mass. When the total drag on the glider equals the
gravity's component in the direction of flight, the glider does not
accelerate any more, it has reached constant speed.
Same thing with an airplane with engine, if the engine quits. As long as
the engine works, though, and we fly level, the engine gives enough pull to
equal the total drag, so that we don't need any assistance by the gravity to
create speed. At level flight, the lift and the down force by the
stabilizer are vertical. Gravity is always vertical. I.e. no fore-or-aft
force component from any of these three forces. Only drag, which equals
propeller pull at constant speed.
Regards,
Svein
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