Backcountry Pilot • C170 & C180 flap settings

C170 & C180 flap settings

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I've always used 20 degrees in my 180, and that seems to be the consensus in the 180/185 Club. With the extra power, 20 seems to be the sweet spot for those aircraft, especially for soft field operations.

Rocky
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I agree with Rocky as I also have a 180 and 20 is the setting I also use. :D
Wild Bill offline
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Quoting from the Cessna 170b Owners manual -

"Takeoff performance figures for 10d flaps are approximately the same as for 20d flaps."

However in another section it remarks that for clearing a 50 foot obstacle 20d is the preferred, as it provides for the best angle of climb performance.

I personally use 20d. Though I don't have any numbers I can feel a slight difference between one and two notches. Perhaps at higher density altitudes takeoff performance might be ideal at 10d instead.
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In my 170 with 220 hp, flaps 20 feels prettty good. I have played around with it a bit though, and especially at lower density altitudes (more power available), I would venture to say that even flaps 30 might do better at plucking me up-and-out of a really SOFT field.... but certainly not a SHORT field. Flaps 30 really pops it up into ground effect early. Then if you nurse the flaps out while remaining in ground effect I can climb with more authority... Keep in mind, though, that I am using the 220 hp motor. I haven't tried flaps 30 in a really demanding soft-field situation though. Just playing around on asphalt... Any other opinions?

M
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"Rule books are paper, they will not cushion a sudden meeting of stone and metal." E.K. Gann

54 170B with stock engine, that's 145 hp for the non cessna people, and flap gap seals. I use 10 degrees of flaps on take off. Without measuring, I don't see a big difference between 10 or 20 on take off. Therefore I just use 10.

My yard is surrounded by trees and on the south end of my strip, therefore every takeoff to the south is over my yard. I leave the 10 d of flaps and pitch for 60 mph until over the yard. I have tried 20 d of flaps and although the plane seems to leave the ground at the same point, 20 feels like significantly more drag. But you guys have now motivated me to go experiment and maybe I'll take a measuring wheel, keep a closer eye on the vsi and altimeter.

Right now our snow is melting but the grond is still froze. The result is a frozen ground and standing water on the srtip. Yesterday I used 10 d of flaps taking off and the water was not a big issue. But landing with 30 d of flaps and the water for drag made for a real short landing. 8)

Bill
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Flap settings

I have used 10 and 20 in my 180 and now 182, like most others say it seems to be the best.
Skylane offline
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Robert "Bub" Wright, aka Skylane, passed away in November of 2011. He was a beloved community member and will be missed.

I've used 20 degrees in most Cessnas I've flown. Note that Cessna did not install a 10 degree detent in the 1952 170 B, by the way, the first notch was 20. I cut a notch for 10 on mine, but found that 20 works best.

MTV
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My ragwing 170 has the small hinged flaps, some people say they're just there to give the pilot something to fiddle with. But mine seems to break ground cleaner taking off with half flaps (about 20'). I generally also use half-flaps for loitering, and pull on the whole enchilada (about 35-wow!) for landing. Even with the small flaps, pulling full flaps on takeoff just when the tail gets light really "levitates" the airplane- no rotating required.

Eric
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Oh boy, Eric, ya did it now! I wasn't gonna say much about that technique because I can feel the sights of a bazooka squaring up on me already! :lol: :wink:

Oh yeah... Starting the takeoff roll clean and plucking about 30 degrees of flap as the tail lightens makes for a rather ballistic early departure from terra firma! Lotsa fun and impressive from the sidelines too... even with just 145 hp. You just have to use a little finesse, though, to nurse the flap out without inducing some sink. With the Franklin 220, it makes this much easier.

M
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