In article writes:
On 2/8/2014 10:13 PM, Bob Whelan wrote:
Gravity does not power our gliders. The forward tilt of lift is what moves
us forward. The sun powers our gliders. ( after the initial boost from dead
dinosaurs)


What came first, the chicken or the egg? I'm with you on the sun being the
power, but I gotta ask - what provides the forward tilt of lift?

Bob - I'll rack out now - W.

Sheesh...I really SHOULD rack out. I'll admit Mr. Sun is crucially important
to us actually soaring (i.e. gaining energy), nonetheless I'm pretty sure the
glider would still move forward in the absence of sunlight...but the FAA
frowns on my testing that hypothesis.

Bob - gravity never quits - W.


The glider would move without sunlight, but (short of the energy applied
during tow), the energy for climbing comes from sunlight.

Gravity provides a force to hold the air here, and a force to act through
distance (altitude) to provide us with foot-pounds of energy.

The forward tilt of lift is a result of the aircraft pitch angle.

Alan