LittleJohn wrote in message ogy.net...
On Sat, 29 Nov 2003 11:32:36 -0800, Eric Greenwell wrote:


Sheesh! So many words and so little knowledge... Here's how it works,
guys.

For any aircraft in balanced flight, there are four forces acting on it.
All forces except gravity act only along the chord or perpendicular to it.
Gravity not only produces a force in opposition to lift,

it can also produce a force in the same direction to, or perpendicular
to lift. 'lift' is the aerodynamic force perpendicular to the direction
of motion. It is the horizontal component of lift that turns a banking
aircraft, and a vertical, downward lift that allows an aircraft to
accelerate in a dive FASTER than the acceleration due to gravity as
when the old Hurricanes inverted to keep the fuel flowing into their
engines when chasing a diving Messerschmidt. If they dove without
inverting first, they'd be chasing that M. in a glider.

Weight is the only one of the four forces that is constant in direction
is an earth-centered frame of reference. The other three forces may
be oriented in any direction though not independently as drag must be
opposite to thrust and lift perpendicular to both. Of course these
defintions are arbitrary, but other equally arbitrary defintions are
less useful.

Gravity is the
'engine' in a glider that produces thrust.

More like it is the 'fuel', the engine is the wing.

--

FF