Fowler flap extention effect on Max Endurance?

[mwrobertson]

I'm trying to find out what type of effect there will be on the Max endurance of a turbo prop aircraft if fowler flaps are extended? I know from experience in a L-13 glider that sink rate can be decreased thus increasing the glide endurance but I'm not sure if this at all translates to a prop aircraft. I've read that the desired effect is to minimize the power required, and that is dependent on the total drag (i.e. thrust required) times the velocity. I've also read that by lowing the flaps you are reducing the induced drag and increase the parasitic drag resulting in the total drag curve moving up and to the left. I know that fowler flaps provide the greatest increase in lift for the increase in drag. The inherent question is, is it possible to move the curve enough to the left and not up too much that the result is a net decrease in power required?????

Please help me out and correct me on what I may have wrong (which I'm sure is something.)

Thanks
-Mike

 

[rb1957]

max endurance is related to minimum drag, so you'd think extending flaps would reduce it (max endurance 'cause of incresed drag).

the trade-off would be the higher Cl would allow a slower airspeed and a lower fuel consumption.

FWIW, i don't think there's much in it.

 

[KENAT]

Probably not, the wing is generally optimized for the most important aspect of the flight envelope. Flaps are a way of tweaking it to improve landing/take off without screwing it up too much during cruise or maneuver or whatever is the critical aspect for a certain aircraft...

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[thruthefence]

I seem to recall "back in the day" the 727 drivers had a 'trick',that by manipulating the leading edge device C.B. and the flap control c.b., they could deploy a just a touch of flap extension, and SUPPOSEDLY pick up a little airspeed without a fuel penalty.

Of course, the aircraft is now operating outside it's certified configuration, but what the heck?

The problem came to light, after a TWA 727 got a bit "squirrelly" during the "adjustment" of the flaps, & nearly crashed. A debriefing led to the discovery that the "technique" was well known among the 727 guys, all over the industry.

Here's an old NTSB link:

http://www.airdisaster.com/reports/ntsb/AAR81-08.pdf