Retracting Flaps On Touchdown

[Pilot DAR]

most of these types need a lot more runway for take-off than they do for landing. The chances of ever needing to land in the absolute minimum distance are pretty much zero

This is indeed the case for nearly all the planes flown by those who frequent here. There are, however, a few aircraft types (PA-18, Husky) for example, which when light get off a short runway and out very well if you work at it. I would venture to say these are aircraft which could sometimes need more runway to land and stop than to clear the hedge.

For the few times I have quickly retracted flaps after touchdown, it was generally to minimize the transition time from wing bourne to weight on wheels for control and braking, or simply control, when you're on skis.

I don't suggest pilots make a habit of this, unless their operations warrant it.

[ifitaintboeing]

One point which hasn't been raised yet, though, is that most of these types need a lot more runway for take-off than they do for landing.

FFF, without wishing to offend and in the politest manner possible, might I suggest you take a look at the C152/172 POH next time you go to fly one. Apart from Cessna only quoting short field take-off and landing performance, you may be surprised to see that the distances are very similar for TODR and LDR.

ifitaint

[FlyingForFun]

For the Cessna 172N, at sea level, 20 degrees, maximum take-off weight, TORR = 835', LRR = 530' - a difference of 305', or, to put it another way, the TORR is over 50% greater than the LRR.

The difference between TODR and LDR is not quite as great, "only" 255'. But these differences get markedly bigger at higher altitutes. I will grant you that the differences are smaller on grass runways... but I think I've justified my ealier post!

FFF
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[Wildpilot]

As anyone who has done a bit of bush work will know, the published toff and landing distances are generally nothing like the real toff and landing distances.
That is not to say I or anyone else should not use them, but often in bush operations rightly or wrongly operations are based on what the aircraft will do rather than what the POH says it can do.

Please don't get side tracked into the use or non use of the POH but it is a fact.

And don't be to hard on yourself for not knowing everything in the POH not many pilots do.

[Big Pistons Forever]

A related issue is what is the definition of short field ? The common answer seems to be along the line of what is the definition of pornography......" I know it when I see it ! "

Given the lack of any official definition I tell my students to treat any field that is shorter than double the POH takeoff/landing chart distance as a short field.

I am curious what other instructors take is on this question ?

[Wildpilot]

If I'm scared on finals and before the takeoff roll its short.

[trex450]

Wether or not it is a good idea to retract flaps immediately after touch down (I understand the idea is simply to reduce lift, increase the weight on the wheels and enable maximum braking) the reality is that if you are going into somewhere that is short enough to warrant raising the flaps then it is only worth doing so with manual flaps. Electric flaps do not come up quickly enough (in my experience) and the extra thought that goes into finding the flap lever distracts from the extra concentration needed to pull off such a landing.

[Sillert,V.I.]

Originally Posted by trex450

Wether or not it is a good idea to retract flaps immediately after touch down (I understand the idea is simply to reduce lift, increase the weight on the wheels and enable maximum braking) the reality is that if you are going into somewhere that is short enough to warrant raising the flaps then it is only worth doing so with manual flaps. Electric flaps do not come up quickly enough (in my experience) and the extra thought that goes into finding the flap lever distracts from the extra concentration needed to pull off such a landing.

I'd agree with this. I found the technique particularly useful when flying tapered wing PA-28's. I remember they would float a long way if you were carrying any excess speed into the flare & there was always a temptation to put them on the tarmac too soon on shortish runways, in which event quickly retracting the flaps was a certain way to get some weight onto the wheels.

[scotbill]

For what it's worth, this was standard practice on DC3s - particularly in strong winds or crosswinds which are endemic in the north of Scotland.,Think of it as the first form of lift dump. X winds are much more demanding in tail draggers and the technique makes sure that the aircraft is going to stick on the ground.

[FLCH]

Had a fella that was taught to retract the flaps on a 172, that was all well, until he was sitting in the left seat of a Bonanza, that didn't turn so well for him.

All I remember was clang, clang, clang and him yelling "What happened?"

Doh .......

[Wildpilot]

Trex450

I have to disagree, I have used this method on the C206 thousands of times into less than perfect strips and all of the C206 in the fleet had electric flaps.

[BEagle]

I remember they would float a long way if you were carrying any excess speed into the flare..

So learn to fly at the correct approach speed! 63KIAS does not mean 70!

The only logical reason for raising the flaps after a full-stop landing is to avoid stones and gravel damaging them.

[scotbill]

The only logical reason for raising the flaps after a full-stop landing is to avoid stones and gravel damaging them.

Maybe from your perspective and your aeroplane.
However, as I have written above, it was a perfectly common part of commercial aviation - although I should have added that it was done by the non-handling pilot. With modern aircraft, lift dump has obviated the need for the technique but I have used it very successfully on aircraft such as the Chipmunk in gusty Xwinds.

[bfisk]

On slippery, icy runways, raising the flaps can help you maintain directional control. Dumping lift to give more weight on the wheels and thus improved friction.

[Tinstaafl]

I used to do it regularly when I was flying in Shetland. Strong & gale force winds, sometimes on icy surfaces, meant that the last thing I wanted once on the ground was a wing producing lots of lift.

[ProfChrisReed]

This is standard practice in most flapped gliders, in this case because aileron authority is reduced with flaps down, but increases in negative flap. Helps to avoid ground looping.

Not relevant to short-winged aircraft, but another example of type-specific differences.

[SloppyJoe]

As this was started referring to something in Alaska you should check out some of this guys clips as most people who have never seen some of the places these guys land in Canada and Alaska do not fully understand what short field can mean.

YouTube - ‪Cubdriver: ALASKA - Cubdriver749er.com‬‏

[Merchant Banker]

Aviation Video: Piper PA-38 Tomahawk - Untitled

[Big Pistons Forever]

Another point which is germane to this discussion is that raising the flaps while the aircraft is still in the air but very close to the ground is a last ditch option for a forced approach where the speed has been allowed to build excessively and the aircraft is stuck in a nose down attitude in ground effect using up precious field length. The sudden loss of lift will cause the aircraft to plop down and allow the nose to be raised before ground contract.

Needless to say this should never be done during a regular non emergency landing.

[good finish]

Use the flaps up technique on the chipmunk for all landings
Is most useful when windy as it helps to keep the thing on the ground