Got a 172n flap usage question

I'm glad to hear you're open to learning new things!

I'm just funnin' you. Well, mostly. I really do use full flap all the time. I haven't found any situation where less flap is better.
 
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Stewartb said:
So you come in with less than full flaps and drooping ailerons rather than just using full flaps? I don't get it.
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Full flaps default for all landings

20 for glassy water

The book says 20, also in practice 20 feels more stable and provides a better profile for glassy water IMO

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James331 said:
Full flaps default for all landings

20 for glassy water

The book says 20, also in practice 20 feels more stable and provides a better profile for glassy water IMO

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Does the book say Robertson on the front? Seriously, does the Robertson supplement alter any float procedures?

Personally I'll stick with what I was taught. I have some great mentors. I've never thought much of Cessna's books. They had to address the lowest functioning pilots in the audience. Hey, No Pilot Left Behind!
 
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Stewartb said:
Does the book say Robertson on the front? Seriously, does the Robertson supplement alter any float procedures?

Personally I'll stick with what I was taught. I have some great mentors. I've never thought much of Cessna's books. They had to address the lowest functioning pilots in the audience. Hey, No Pilot Left Behind!
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I gotcha, maybe I'll play with it a little more, so far the 20 seems to have made for some smooth glassh landings.
 
Hey, I can do it with full flaps, Karl prefers less, you're experimenting, it's all good. There are many ways to land a Cessna floatplane. I am curious about your aileron droop and the Cessna procedures, though.
 
Ron Levy said:
For takeoff, 20 is too much in a 172N -- adds a lot of drag. If you look in the 172N POH, it recommends zero flaps for both normal and short-field takeoffs;10 flaps are recommended only for soft-field takeoffs. FWIW, the later 172P POH recommends 10 flaps for short-field as well as soft-field, but there's no aerodynamic difference between the N and P, and when I asked Cessna, they said they had no explanation for the difference. However, I tend to do what the book says unless there a good reason to do otherwise, so I'll do 10 flaps for short-field in a P, but zero flaps in an N.

For landings, while the book just says "as recommended" for normal landings, and that normal landings "can" be made with any flap setting The POH also specifically recommends full flaps for short-field landings. Further, the airplane as enough lateral and directional control to make landings with full flaps in crosswinds of twice the demonstrated maximum crosswind component, so there's no need to reduce flaps for a higher approach speed in crosswinds. Further, my experience is that most pilots do best that which they do most often, and those who vary the parameters on every landing tend not to make good landings routinely. All things considered, my feeling is that if you want to be good at landings, you should use one setting all the time unless you have a really good reason to do otherwise (the occasional no-flap landing to practice for electrical power loss excepted). Which setting? Well, full flaps maximizes drag to reduce float (and thus landing distance) as well as allowing the lowest landing speed, minimizing wear on the tires and brakes. So, I land 172's with full flaps, period, using 1.3 Vs0 for the actual landing weight (typically about 55-60 knots IAS depending on load). I use 10 on downwind, 20 on base, and full flaps on final. Also, trying to set 30 flaps with your system is not likely to give you a consistent flap position, which is why I recommend sticking with the detented positions of 10, 20, and 40.

BTW, a 152 won't float significantly on landing with flaps extended unless you're landing too fast, but that's not an issue for you now.
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What he said. I was taught 85kts/10deg downwind, 75kts/20deg base, 65kts/full final, but I think I might try your 55-60kts because I still tend to balloon/float a bit at 65.
 
I owned a Robertson 180 seaplane. (actually the first Robertson 180 ever made...from their old shop at Bellevue) It didn't have a seaplane supplement. But it did have an extensive landplane POHS.

They painted "Robertson STOL" on the tail with a paintbrush!!
 
FWIW, my primary flight instructor back in 1966 told me with the Cessna paralift flaps that from zero to 20 degrees you're adding mostly lift with little extra drag and from 20 to 40 degrees you're adding mostly drag with little extra lift.
 
If you view the Robertson FMS that James linked you'll see that the max performance take-off calls for 30* flaps. That with a Robertson will also droop the ailerons. Which goes to my comments in other threads about my preference for more than book flaps occasionally. It works as long as you have enough power. Remember, the POH is written for gross weight ops. Sometimes we fly lighter than that.

I know most of you think high speed taxiing and similar flight testing is dangerous. I don't. Here's a demo some of you can try for yourselves. It's easier with manual flaps and is especially useful with tail draggers. In a Taildragger land full flaps on the mains and push the controls forward to hold the tail up. As you slow you can feel the elevator getting a little heavier. Dump the flaps. You can't hold the tail up no matter what you do. Now let's try the reverse. On a long runway with normal take-off flaps add power and lift the tail. Reduce power to keep the tail up but not fly. Pull more flaps. You're flying. Since 30-40* flaps are so draggy and I've been told using them at take-off is stupid and dangerous, how do those demonstrations figure in? Flaps are a great tool. Manual flaps are better. Manual flaps on a taildragger better again. Performance right there in your hands.

James, you need to do the same flap settings tests on floats. Get on step and see what flaps can do. You might need to adjust the trim to get the best results.

Cheers.
 
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Stewartb said:
.................. On a long runway with normal take-off flaps add power and lift the tail. Reduce power to keep the tail up but not fly. Pull more flaps. You're flying. .......................
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You're also effectively increasing the angle of attack, you could do much the same thing by simply pulling the nose up a little instead of deploying more flaps.
Over time we all develop techniques that may or may not be according to "Hoyle" but they work for us, for example on a short field takeoff with my 170B I'll typically start rolling with one notch (10*) of flap and then jack in another notch (20*) while I'm rotating. Then after liftoff as soon as the airspeed hits the bottom of the white arc I'll drop back to 10* and retract to zero at 70 mph. You won't find that in the manual but it's my habit and I'm comfortable with it, altho' I won't say I wouldn't have the same result simply by increasing the AOA a little more with the elevator instead of deploying a second notch of flaps :dunno:
 
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I think executing a missed approach with 40% of laps is a little too much for student pilots. I have my students in my 172 M using 10 degrees on downwind at 80 knots down to 800 feet during base, 70 Knots and 20 degrees and 600 fee turning final, and 65 Knots and 30 degrees on final dropping to 55-60 just before the flare. I impress upon my students that the speeds, flap settings, and altitude are dependent upon wind conditions and position (extended, short, simulated engine out etc.) I personally use 40 degrees of flaps to demonstrate its effects to my pre private students and obstacle clearance practice. A general rule of thumb for PPL folks is the max flaps that will still provide rudder control thru touchdown which applies to all aircraft I have flown (General GA single engine).
 
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