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!
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.
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.
pdb ....sounds like you need to find a Javelin tank set up.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
From time to time they show up for sale in The Flypaper, and the salvage yards sometimes have them. If you find one, let me know. I have the installation drawings, etc.
O & N sells their baggage aux tank set up, which is very similar, but I believe it is STC'd for the 172...not the 170. A field approval or one-time STC would be req'd. The beauty of the Javelin kit is that no further basis of approval is necessary, as it is approved by Type Certificate A-799.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Cessna® is a registered trademark of Textron Aviation, Inc. The International Cessna® 170 Association is an independent owners/operators association dedicated to C170 aircraft and early O-300-powered C172s. We are not affiliated with Cessna® or Textron Aviation, Inc. in any way.
