C172 short field landings
 

Hi guys.

I was just wondering if anyone has any contributions to make regarding the best technique of landing a new,very clean airframe C172R on short,grass strips.

i am based out of a large airport,and have surprisingly little experience on the latest 172s on short grass strips,having flown many hours in older ones,which have flap 40 deg and are generally much 'dirtier' airframes,so the 172R seems to float forever...a problem if you're heading for a ravine at the rwy end and still haven't touched down...:{

thanks:ok:

A fairly simple one, get the speed right!! 60 to 65-ish knots is plenty quick enough. The vast majority of problems with landing are down to speed control, slow it down to remove some energy and it'll probably be fine.

yeah,in fact its quite odd-i get it down to 55 kias and it still floats-flaps 30 (max).was wondering if taking about 5 deg of flap AWAY as i enter the flare might help????

Only if you want to slam dunk it on.

I haven't got a 172R POH to hand but what I normally do when I fly a new type is to take it up to a sensible altitude and configure into landing set up.

Do few stalls like that. Note stall speed. Multiply by 1.3 and you have now the correct approach speed for your aeroplane at that weight.

If conditions are very smooth and you are very au fait with the aeroplane you may be able to nibble off a bit and fly the approach at 1.2 * Vstall.

Of course adjust for other factors as required in particular gusty conditions.

FD

I wouldn't ever recommend raising flap at that stage, all sorts of odd things may happen, what would you do if you then got assymetric flap for example?

Use the correct techniques, try out some shortfield landings on a longer runway until you get a feel for the machine, before trying short strips. The 172 is an incredibly docile machine, it just needs a bit of practise like any other.

Try doing some upper airwork at speeds just above the stall, this helps build up "feel", something I think that is more important than numbers sometimes.

FD's suggestion is a good one.

thanks a lot for the input...much appreciated:ok:

Agree with SAS and FD - sounds like you're too fast down the approach; that's the only reason it'll float when it should land - but at least it sounds like you're flaring it properly, not driving it on nose-low as so many 172 drivers do - until one day the noseleg says 'stuff this for a lark' and breaks off.

The 172 is a lovely machine to land if flown at the right speed, those super Fowler flaps fully extended, to a correctly fully flared nose-high touchdown making full use of that sensitive elevator. Don't mess with the flaps - leave them down as Mr Cessna intended, and the aeroplane will be a pussycat to land.


As an aside, last Saturday morning two of us about to start our Concorde guide duties at Manchester were chatting when we noticed a Virgin 747-400 approaching 24R. It touched down fully-held-off, well nose high, with it being difficult to note the exact point at which the wheels took the weight - the gear just slowly contracted as more weight came off the wings and onto the wheels. The pilot kept the nose right up high, almost to the point of stopping on the runway, before it was gently lowered to the ground and the aeroplane taxyed off at the next taxyway. Beutifully done - we had both stopped chatting to watch, and it was a pleasure to witness someone really on top of their game like that.

SSD

Easier said than done :) - I've just got back from my SEP rating re-validation flight in a new 172 and in several configurations it really wasn't easy to persuade it to stall at all without doing quite ludicrous things to it.

I practiced short field landings in one of these recently and found that 60 over the fence worked, anything higher and it floated forever.

Our 172 SP does fine with full flap and 61kts IAS.

One point, I wouldn't ever describe any Cessna (apart from the citation) as having a 'clean' airframe, marginally less draggy perhaps!

RUDAS

IMHO, the 172 is a very underrated flying machine, it has a very effective wing that generates loads of lift and must be flown at the right speed "over the numbers."

I wouldn't b*gger about with the flaps if I were you, but I might consider ASI position error.

What speed does the book say you should approach at? If you are flaring enthusiastically, could your ASI be under reading? Are you flyig solo or one up?

Sounds to me as if a few circuits with an instructor could be helpful, really get to grips with the beast.

Although most of my hours have been on PA28, I have about 30 on 172s, from the F model to the P (not the R though) and that lovely wing keeps producing lift down to about 30kts :D

A stalled wing produces no lift. That happens to the 172 at speeds well above 30KTS.

FD

FD

I missed out the word "some" before lift, my typo and if we are being careful with words, the whole wing does not stall at once, it stalls progressively due to the washout built into the aerofoil profile, with the resulting pitch down being somewhat above 30 knots ;)

Yup, if you check out a Cl/AoA curve you'll see a wing does produce lift below the stalling AoA :p

(although try not to keep that in mind when you're gliding down the runway at 55 knots considering raising flap :cool: )

Cheers,

Jack.

the last time i was on this forum was about the flap raising issue, you will not "slam dunk " onto the ground if you are only 3 feet up wend you retrack flap. Short landing .. Two most important thing's; speed and most important is ROD, You can have the best speed control in the world, but if it is to flat you will float. You have to be :Behind the drag curve and need power to control the rate of descent, control speed also by power and that thing at the very back of the aircraft, drive it all the way to the ground and at the last moment round out , add a small amount of power to arrest the ROD and stop. Taxi alllllllll the way to the end of the strip

Spot on FU!

SS

Halfbaked_boy wrote

Let's be glad it does. Aviation wouldn't exist otherwise. It even produces lift above the stalling AoA.

Regards

Gerard

retracting flap on landing can be quite helpful...During the initial stages of the touchdown, retracting flap will provide you with a little sink to help shed off that float and most importantly once on the ground puts more of the weight on the main wheels sooner giving you much better breaking performance. This far outweighs any drag they may be providing during the landing roll.

Rudas:

I have a Reims Rocket, but previously have frequently flown other 172s, particularly the P model.

Other people have made the point about speed control on final approach. 60kt is right for a normal short field landing, perhaps a couple of kt slower if at light weight.

However, what about power? Some instuctors teach the advantages of leaving on a 'trickle of power,' particularly when flying four up. This does tend to produce smoother landings, but will cause a lot of float. If you're looking for short landings, make sure the throttle is closed as you flare.

AA

You shouldn't ever have to resort to raising flap to reduce float. This is an artificial reduction in lift, rather than just flying the a/c correctly.

Why shouldn't we play with flap in the flare?
1) Assymetric flap retraction.
2) Pitching movement caused by movement of the centre of pressure.
3) Time. How long does flap retraction normally take?
4) If you are floating, you normally have too much speed, so if you retract drag flap, you will slow down less quickly. On Cessnas, the 40 flap setting is not there to primarily increase lift, but to increase drag. So why would you get rid of it?

Fly the machine correctly and you won't have to resort to daft things like retracting flap in the flare.

I am a believer in raising flap if the need arises, BUT as SAS has just posted, it should not be needed.Speed and trottle control all the way down, flare to arrest the ROD, close the trottle and touch all as one movement.

SaS

I agree entirely with your view.

Unfortunately, as a matter of fact, the 172R has only flaps 30 as land flap, since the 40 degree setting was deleted on the P or N model (can't remember which.) It's a shame, as that last 10 degress gave some very useful drag.

Still, it shouldn't need test pilot tricks to land ;)

Dumping lift, once all three wheels are down, is another matter. I believe (from memory) that the POH for one series of the Cherokee 6 mentioned this in the short field landing context - but you need to have a manual flap lever and it's a technique that would make me nervous in a retract, where there's too much risk of pulling the wrong knob! And you have to do it by feel, since looking in at this stage is pretty risky.

Ah yes! I can't really understand why they got rid of the 40 setting, as you say a very useful thing, especially on shortfields or when you've bu**ered up an approach.

The dear old 150 I trained on couldn't climb with flaps 40 and I believe go-around accidents were behind the change. Maybe someone has chapter and verse.

But the Go around drill is always to increase power, carb heat cold and reduce flap in stages to 15. If people are trained correctly, then this should never be a problem, but then again maybe cessna are scared of law suits. How sad.:(

Well considering Cessna stopped producing aircraft for 10 years for that very reason I think they probably are!

I like the 40 degree option too
it is after all only an option
T2

A chap I knew had to force land a 172 solo and used 40 degree flap. Unfortunately, he skidded through a gap in some trees in a hedge and both wings broke and folded back.

With the flaps in their barn door configuration, they had sliced through the back windows and god only know what the outcome would have been if there were pax in the back.

.......... and that is of course why one should always do a flapless forced landing. :ugh: :ugh: :ugh:

Good way of stopping quick, though :}

Flaps
 

I once inadvertently selected flap up from flap 30 on a go around!

Any flap change on the 172 means a load of pushing forward on the control column but this flap change leaves u pushing like Arny and gluing your eyes to the ASI hoping the speed will will increase quickly!

Short field landings in the beast are as previously said, all about speed and nailing the attitude during the approach. Don't flare too soon and chop the power when u think you are over the hedge.
The rest is down to how your cards are dealt on the day!

Coop & Bear

Actually David V, the wee 150 could climb with full flap. In my very, very early days, I flew all the way to Downwind on a go-round with Flap 40. (One of those extended newbie brain-farts) The climb was slow, but not non-existent. That said, it felt very odd. And yes, I do know it's not the best way to carry on.

But aren't they forgiving little machines??

Coopervave, 'chop the power when u think you are over the hedge' sorry not quite right. The flare, the throttle closed and the touch down is all one action, If you are closing the throttle 10 feet up you still have no control on the touch down spot, and for strip flying this is not good. You must be able to hit the spot every time in a full stall , No yes \no \maybe

fu 24 950,

what do you say to those who chop power downwind abeam the numbers?

Slim

"Autorotate" - see FU24s profile for explanation - explains a bit about the underpinning theory too ;)

BTW, FU24 is a Fletcher Ag aeroplane, bit of a short strip animal.

c-172 40 FLAP
 

One not often discovered reason for abandonning 40deg flap settings...
On early model 40 flap versions..try a very low speed approach with full flap. say at about 45kts ias. if you are too high on approach and apply full slide-slip (max rudder) the diverted turbulent airflow from the 40 deg flap over the tailplane will cause an instant and complete tail-plane stall with sudden violent nose down pitching moment.
very alarming and clearly fatal at less than 50ft agl.:{

Nice point rodneyblois , i hadn't considered that.

I was told the reason flaps 40 was elimated from the 172R was that some pilots were having difficulty holding forward-pressure at max power in a go-around.

From the 172R POH: Stalling speed.

Vs-clean: 44KIAS. 1.3Vs = 57KIAS

Vs-full flap: 33KIAS. 1.3Vs = 43KIAS

Slim, (a) put the power back on and (b) if it has number's it is a airport, not a strip. Also can we get away from saying "chop power", it sound's rough, where as "closing the throttle " is a better term to use .

Point of information.

The last mark of 172 to be have the 40 flap setting was the 172M. Subsequent marks only have 30 degrees. The later models also have the "lever-in-a-slot" rather than the switch and gauge for lowering the flaps.

(at least this is true of the M, N, P, R and S models of 172 that I've flown)

However the 182 still retains the 40 degrees setting.

Brooklands

Brooklands,

At the risk of being pedantic ....

Not so, my friend : the N also has 40 degrees available, and they work very well, too !

FF :ok:

fu 24 950

Obviously you understood enough to answer the question.....

Cannot say I agree with you, but that's one of the highwing/lowwing debates. So nice to land a plane on the exact spot you chose when flying downwind, with no power from abeam the numbers. And if you are trying to get onto a real short strip with lots of high trees at the end there's nothing better than slipping it in (power off).

Ag pilots know nothing of this of course, they think you need oxygen above 50ft AGL :)