Posted: Sun Oct 17, 2004 1:22 am
Randal is right...its to give me more options (read more range) in the event of adverse, unforseen weather. You do that by flying just a bit faster than best glide (max L/D). My back of the envelope flight testing suggest that best L/D is about 88. That figure seems to be generally consistent with the tables in the POH.blueldr wrote:A question for pdb. ----- If you were flying the trench which at 400 sm is well within the normal range of a C-170 (A or B) in still air, you would have no reason to slow to 88 mph for fuel conservation. If you were bucking a headwind that was eating into your fuel mileage, 88 mph would surely be the wrong thing to do.
I don't see what advantage 88 mph would be other than to save fuel in a tailwind. Enlighten me!
Your right about the headwind, slowing up is the wrong thing. I would speed up at least about 1/2 of the headwind over best glide. In a 20 mph headwind I would fly no less than 98 mph. (88 +1/2(20).
In a tailwind, I would slow up but no slower than min sink. Unfortunately I don't know what minimum sink (-0- power) is so its a bit academic for me at this point.
Unortunately my 170 is a lot slower than many because I have big tires, bubble windows, and an 80/40 prop. That knocks quite a bit off my normal cruising speed so the whole issue of range become a bit more serious. Gas is not always available along the route so getting half way before turning back can increase the excitement factor more than I like.
