"David CL Francis" wrote in message However if you fly for maximum range
than you fly close to maximum lift/drag ratio which depends only on
getting the correct alpha (ignoring compressibility effects).

If the correlation between thrust and fuel burn is fairly linear, this is
correct. A piston powered airplane with a constant speed propeller will
achieve max range at any altitude it can sustain the correct alpha angle.
Jets do not have a linear correlation. The jet I fly gets the same fuel burn
at 5000' and 250 KIAS as it does at FL350 and 440KTAS.

So since lift = weight, drag depends on weight and it reduces as fuel is
burned.

Remember that there are 2 kinds of drag- Parasite and Induced. Parasite drag
is dependent on speed. Induced drag is dependent on alpha angle (among other
things).

I suggest a book called 'Aerodynamics for Naval Aviators'. Most good pilot
shops have it.

D.