> > > A glider is
> > > "propelled" by the forward - in the direction of flight - component
> > > of the aircraft's WEIGHT only.
>
> And thats why they (gliders) obviously fill also sometimes their
watertanks -
> to get more load, to feed gravity and to get speed?
>
> Cheers, Raimo
>
Yes, Raimo, that is one of the main reasons for the water ballast. At the
same glide ratio, you get higher speed with than without ballast.
Just look at the bottom illustration in my first e-mail: Higher weight
gives larger gravity component in direction of flight at the same angle of
flight vs. horizontal. Larger pulling force gives higher speed - the glider
accelerates until the higher pulling force equals the increasing drag.
Higher speed gives higher lift (square of speed increase) to carry the
higher weight, so that you can maintain the glide ratio (direction of flight
vs. horizontal).
Regards,
Svein
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