flaps on takeoff (1/2 none full)

[autoalain]

Folks,  an old bird   m20a,  took over ownership 20 years ago from original owner (spitfire pilot ) ww2,

he taught me 1/2 flaps all the time on takeoff,  was the old guy correct? been doing it for 20 years no problem, but just wondering

what the experts say to do. p.s. some of his other rules were just plain wrong, that is why I'm asking.

[StevenL757]

What does the AFM state?  With respect to the previous owner, this should be your main source of guidance.

[Raptor05121]

Doesn't the M20A have manual flaps on a J bar? On my C, two pumps of the hydraulics will yield 15 degrees of deflection

[gsxrpilot]

Have you ever tried taking of with no flaps? How about full flaps? Maybe it's time to move beyond the primary school method of do what teacher says, and learn about your airplane.

[kpaul]

I have used all three settings, however I tend to use the take-off setting on mine.

[gsxrpilot]

6 minutes ago, kpaul said:

I have used all three settings, however I tend to use the take-off setting on mine.

I expect it's very useful to know how the aircraft performs in all flap conditions. Then use the setting that makes most sense for the conditions when able, and be unafraid when conditions and settings are inappropriate in an unexpected situation.

[kpaul]

Just now, gsxrpilot said:

I expect it's very useful to know how the aircraft performs in all flap conditions. Then use the setting that makes most sense for the conditions when able, and be unafraid when conditions and settings are inappropriate in an unexpected situation.

I agree.  My transition CFI had me do all three during my flights with him. 

[201er]

1 hour ago, autoalain said:

Folks,  an old bird   m20a,  took over ownership 20 years ago from original owner (spitfire pilot ) ww2,

he taught me 1/2 flaps all the time on takeoff,  was the old guy correct? been doing it for 20 years no problem, but just wondering

what the experts say to do. p.s. some of his other rules were just plain wrong, that is why I'm asking.

I would agree. I see no advantage of taking off with anything other than takeoff flaps in normal operations.

[PTK]

If rw length is not a factor, i.e. >4000 ft or so, I prefer no flaps. I like the smooth liftoff and climb w/o flaps. 

[AZM20C]

I try to follow the Operators Manual on my 74 M20C. It seems to work like a charm.

 

[bradp]

My plane absolutely hates climbing on full flaps.  I would generally avoid this setting - kind of goes with the flight manual / AFM / POH or whatever you have's general guidance or spirit.  It loves climbing on either takeoff or no flaps.  

When selecting flaps or no flaps also consider the conditions of the runway.  Anything less than a nicely paved runway in good condition I'd use takeoff flaps to limit your speed on the ground and exposure to the crud. 

[Hank]

I've done a full flap takeoff once. Took a little while to figure out what happened, it was just all wrong and not something I want to do again.

My normal departures are no flaps. Works great on 3000' paved fields. When heavy or leaving from grass, I'll use Takeoff flaps. It's just one less thing to forget on climbout, and I don't get that queasy feeling as I go over the trees and raise them.

[jlunseth]

The numbers in the performance section of the POH that tell what length runway is needed for takeoff, short field, etc., all assume takeoff in the configuration specified.  In my POH (231) that is in the "Normal Operations" section.  That said, if you have plenty of runway there is no reason no to go no flaps, it does eliminate the need to remove flaps at low altitude.  As was said, it makes for a smoother transition from takeoff and climb.  Just bear in mind it also increases your stall speed, which is the main reason for using them for takeoff in the first place.  I always use half flaps for takeoff, it is during landing where I will use no, half, or full depending on conditions and what I want to do.

[gsxrpilot]

I would never advocate takeoff with full flaps as normal, but it's good to know it will work in the event I'm all set to land with full flaps and the runway is unexpectedly fouled in some way and I have to go around.  It's important to already know what will happen and what to expect. Therefore it is good to try it once or twice in a very controlled environment, i.e. long runway.

 

[Hank]

4 minutes ago, jlunseth said:

The numbers in the performance section of the POH that tell what length runway is needed for takeoff, short field, etc., all assume takeoff in the configuration specified.  In my POH (231) that is in the "Normal Operations" section.  That said, if you have plenty of runway there is no reason no to go no flaps, it does eliminate the need to remove flaps at low altitude.  As was said, it makes for a smoother transition from takeoff and climb.  Just bear in mind it also increases your stall speed, which is the main reason for using them for takeoff in the first place.  I always use half flaps for takeoff, it is during landing where I will use no, half, or full depending on conditions and what I want to do.

Oh, you mean this! There's no listing for gear down, zero flaps, but I only see a 3mph difference from clean to gear down and half flaps.

I won't bore you with the Takeoff Distance table and that cool drawing, but it shows 620-745' ground run between 59-100ºF plus another 455-545' in the air to reach 50' agl. Which means there's no problem at my former 3000' home, nor my current 3200' home field . . . Oh, those are zero wind distances, too, and I hardly ever get to see those. Oops, that's not at gross weight, but even then [gross weight, 100ºF], it's 1030' on the ground and another 730' in the air, still no problem since I use flaps at or even near gross weight.

[Hank]

3 minutes ago, gsxrpilot said:

I would never advocate takeoff with full flaps as normal, but it's good to know it will work in the event I'm all set to land with full flaps and the runway is unexpectedly fouled in some way and I have to go around.  It's important to already know what will happen and what to expect. Therefore it is good to try it once or twice in a very controlled environment, i.e. long runway.

 

Taking off with Landing Flaps and Takeoff Trim is a whole different ballgame than a sudden, low-level go around with Landing Flaps and Landing Trim. The first time you try that, please be plenty high!! I find the trim has a more pronounced effect than the flaps do, and can require significant arm strength while spinning the trim wheel! But then, your nice new ride has electric trim, so you can push with both arms . . . . . 

[gsxrpilot]

3 minutes ago, Hank said:

Taking off with Landing Flaps and Takeoff Trim is a whole different ballgame than a sudden, low-level go around with Landing Flaps and Landing Trim. The first time you try that, please be plenty high!! I find the trim has a more pronounced effect than the flaps do, and can require significant arm strength while spinning the trim wheel! But then, your nice new ride has electric trim, so you can push with both arms . . . . . 

I was demonstrating once to a CFI, that my M20C would almost land itself with full flaps, full up trim, and power off. When just a few feet off the runway, the CFI asked what I would do if I had to make an emergency go around. I immediately demonstrated it.  Full power, hold the yoke forward with left hand, trim furiously with the right, get the gear, and finally the flaps, climb back into the pattern.

It's not real easy, but is plenty doable. The electric trim in the new one makes it easier.

[DMJones]

In the FWIW department, flaps are more for obstacle clearance on t/o than anything else.  On big planes the shorter the field and higher the obstacles, the more flaps we use.  The only time I could see a Mooney needing full flaps might be on a 2000' strip in the mountains.  On a 10,000' strip by the beach, I see no reason to fear a no-flap t/o.  As with all things, there are always trade-offs: what is the effect on an abort, a go-around, engine loss, power-failure, etc...

 

With more flaps, and without having done in-depth research on the M20 (read any), I'd expect your angle of climb to increase with more flaps.  So, it would be reasonable to assume you'll be higher quicker, so you'd have more altitude with which to work in the event of engine failure.  Using full-flaps likely increases that angle, but would correspondingly increase drag, so the slight gain likely negates the advantage in the event of that same engine failure...

Just my humble opinion.

 

[201er]

2 hours ago, DMJones said:

In the FWIW department, flaps are more for obstacle clearance on t/o than anything else. 

Flaps also reduce the amount of time you spend rolling the wheels on the ground or blowing debris around with your prop.

Edited June 26, 2017 by 201er

[Skates97]

In my experience having more than take off flaps made climb performance worse. In my transition training my CFI had me do a takeoff with three pumps on the flaps, so maybe around 22-23° or so? (Two pumps is 15° and 4 1/2 is 33°) It was on a 7,000' strip and he wanted me to see what it would do. We came off the ground quickly, but it did not want to climb at all. Once I flipped the lever up to retract the flaps we started climbing normally. It seems that somewhere past the regular 15° take off flaps climb performance degrades.

[PTK]

On 6/26/2017 at 5:33 PM, Skates97 said:

In my experience having more than take off flaps made climb performance worse....It seems that somewhere past the regular 15° take off flaps climb performance degrades.

Of course! Flaps increase wing surface area and curvature thereby increasing lift, and consequently drag. When you increase lift at a given airspeed you also increase drag. There comes a point where drag increase is greater than lift increase. That point for us is take off flaps and anything beyond that is results in too much drag. Lift is still being produced because the airplane is accelerating but drag is just too great to climb. Great for landing when we want to sustain lift at lower airspeeds but for take off not so much. On landing the increased drag from full flaps can be overcome by thrust and by trading altitude for airspeed. Potential energy to kinetic.