Flaps 30?

[squeakmail]

Another one that I'd be interested in hearing your individual comments on.

A current trend seems to be to use 20° of flap as a normal setting for touch down in a Cessna 150/152 and only use 30° for a short field (performance, call it what you will) landing.

This good or bad?

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LIVE in peace...or REST in it!

[polar bear]

Why not use all the flaps you've got?? I always do, like I was tought to do...

Exceptions of course confirm the rule, e.g. strong X-wind...

polar bear

[Capt Homesick]

If you've got a reasonably long runway, then there is an argument for teaching flap 20 to make the roundout a bit less dramatic. I taught 30 as normal, but encouraged studes to practice with 20 as well, because it made crosswind landings a bit easier.

[Airprox]

I like to teach people to normally land with flaps 20 and to use flap 30 if they need it (too high, too fast). Seems to work nicely.

[catstone]

I agree with Airprox. Teach 'em to use 20 flap, keeping the extra in reserve should the approach start looking out of shape. I occaisionally fly a 172 with 40 flap available. It will recover almost any bodged approach but go-arounds can be very hairy !

[squeakmail]

Just to stir the argument a bit...

Doesn't the aircraft manual suggest full flap for landing normally...thereby reducing the touch down speed, the wear and tear on the undercarriage and the landing roll (with subsequent reduction in runway occupied time) ?

Are we starting to re-write manuals again?


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LIVE in peace...or REST in it!

[straight&level]

I agree with the above.The handbook gives 30 flap for a schedule performance landing,one of the items that a commercial student would have to be tested on for his/her GFT.There is however an argument for the use of less flap for landing in a strong crosswind.

[Tinstaafl]

I'm on the full flap side. Slower speeds, slower touchdown speed, more time to judge what's happening etc

That being said, I have found it useful for some students to use partial or no flap while initially learning to land since that can minimise trim changes & require less of a pitch adjustment to flare.

I also tend to less flap in crosswinds that are at or past the recommended max x-wind limit. The slightly faster IAS makes the controls more effective while also reducing drift (for a given wind velocity).

This has to be balanced against the longer runway needed, wear & tear, reduced visibility ahead etc...



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Fascinating how scientists & research engineers have managed to make aircraft that all use the same laws of aerodynamics all over the world.........Has anyone thought to tell the CAA?

[Thumperdown]

Yip agree with the full flappers!
Says so in the manual so why not?Why fit them if your not supposed to use them? Also reduces brake pad wear.

[Bendo]

I'm in the Full Flappers (except strong X-wind) school... for everything I fly from Chipmunk to 150 to Cherokee to Chieftain.

Except the Bird Dog...

... the 60 degrees flaps is a bit much!

[Ace on Base]

My two cents........

As per the manual. If the manual perscribes 40 degree flaps, then 40 it is.

There is a reference in this thread from straight&level about "Performance" landings... I ask, should we be teaching anything but the book figures?? Are we "test" pilots that know better than the manufacturer?.... All take off and landings should be conducted to book figures, ie become "performance" type manouvers, Any reason why they shouldnt? please enlighten me!

I do have a question though, and would love to hear other points of view:

Should flaps be retracted during the landing roll, to reduce lift and thence increasing the weight and the braking performance, therefore reducing the landing distance, OR, leave the flaps - because it acts as an airbreak, therefore reducing braking distance automatically, and the pilot can veer of the runway if their attention is diverted??

I am sure this topic has already been flogged to death in this forum, and I already have a reason and justification for the way I teach - but I am interested in seeing answers from different instructors.

Regards

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"Keep Smilin' Sunshiners!!"

[Ozgrade3]

One of my students is having problems with the flare on landing, he's not applying the correct amount of back pressure to raise the nose wheel clear of the runway to efffect a main wheels first touchdown.

In this case I've found that leaving the flaps at 20 degrees reduces the amount of pitch change required during the roundout, resulting in much better consistancy of landings.

[Capt Homesick]

Ozgrade3, agree completely. Ideally, he would be using flap 30, but get him confident, and work him up to it!

[BEagle]

No - keep persevering with him until he's competent at landing the aircraft as the designers intended!! By the way - are all those older C150s with 40 flap now dead? I remember that a full-flap go-around was only really successful due to the earth's curvature with 2 POB and any fuel at all!!

[Capt Claret]

Ace on Base,

Best leave flaps where they are until at taxi speed. Reasons? Good technique to transfer to larger aircraft and lessens the chance of folding up the gear instead of the flap.

OzG3,

try teaching your student the landing attitude, rather than to apply backpressure. An attitude can be seen by both of you, but how can you tell just how much back pressure the student is applying.

More importantly, how can you describe how much back pressure to apply.

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bottums up !

[arrow2]

BEagle,

The 40 degree C150s are alive and flying!! I have just sold my share in one at Blackbushe -there is another one there as well at the moment - both are C150E's with the old "square tail".

Arrow 2

[europhobe]

Capt H.
30 degrees hardley makes for a 'dramatic' roundout. 40 degrees on the older 150s - now that can be dramatic.

Any comments on this x-wind theory I was taught? Landing flaps (ie 30 degrees or more)destroy ground effect thus once on the ground, the plane stays on the ground and less chance of skitting sideways across the runway.

[chicken6]

Full Flaps!

Tyres, brakes, distance etc. etc. except xwind yada yada reduced flap so approach speed is higher so ailerons work better in flare.

Agree with catstone - 40deg in a 172 makes it hard to overshoot! I occasionally fly a C172 XP with 195hp six cylinder engine and CSU - very nice in cruise but overshooting I almost have to lock my elbow straight until the first 10deg at least comes up.

Teaching students to raise the flap only when off the rwy...I had this brought to my attention only when starting my twin rating. I realise it's a R/G problem now and hadn't thought of our Arrow but that's a bloody good idea.

Unlike the ground effect one - does the wing still produce lift when on the ground and moving at 50 kts (C152)? What about 40? 30?

Yes, but not necessarily enough to completely support the a/c weight. Surely flaps would increase the G/E? Maybe in a low wing with slats [i]they[i] might reduce g/e like an air dam on the front of a rally car, but flaps? I don't think so...

Safe flying :)

[DB6]

Ace on base - just reading through the manual for the Warrior today (as you do) and it states that maximum braking is achieved with flaps retracted and the weight off the nosewheel i.e. with the maximum weight possible on the main (braked) wheels. I take the point about aerodynamic braking but at the speeds we're talking about and the flap areas on e.g. a Warrior I don't think it will be a major factor. As to the first question, during my checkout last week with an RAF CFS instructor full flap for landing was most definitely the order of the day, and I tend to go with what they recommend.

[ComJam]

I've taught on both 30 and 40 degreed Cessna's.

In 152's I usually taught full flap because the larger flare becomes the norm. Therefore the student doesn't have to consider short field full flap landings as anything out of the ordinary.

In the 40 flap 150 we routinely taught 20 flap landings as the attitude at full flap was much steeper and could be off-putting. 40 was taught for "performance landings" with a lot of emphasis put on the go-around from that position. As you know even a 130HP engined 150 Aerobat is a pig with the "barn doors" out!

:)

CJ