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-   -   Stalling in Landing Configuration...? (https://www.pprune.org/private-flying/607786-stalling-landing-configuration.html)

BackPacker 16th Apr 2018 12:47


Originally Posted by Flyingmac (Post 10120155)
"But the OP question was specifically about the biannual checkride."


What is that?

It's the FAA way of maintaining currency. In order to fly a SE aircraft you need to have done this specific checkride, called the biennual flight review (BFR), with an instructor in the last two years.

Flyingmac 16th Apr 2018 13:03


Originally Posted by BackPacker (Post 10120171)
It's the FAA way of maintaining currency. In order to fly a SE aircraft you need to have done this specific checkride, called the biennual flight review (BFR), with an instructor in the last two years.



There was I thinking it meant twice a year.
https://www.google.co.uk/search?sour....0.cb-rrFwal_Q

scifi 16th Apr 2018 13:10

Just a few words about this 'landing configuration'.. I have looked through my PPL course details, including the Pooleys Pilot's Work Book, and 'Landing Configuration' is not mentioned for Ex.10A Ex.10B or Ex11.
I also had an Instructor who asked for TTTT when approaching a Waypoint, which turned out he meant Transit, Turn, Trim, and Talk.
Where these terms come from I have no idea, maybe they are used in USA.


I have encountered the 'wing-flip' stall once when encountering my wake turbulence during a complete orbit, It flipped me out of the turn very quickly.

Pilot DAR 16th Apr 2018 13:26

While discussing the angry handling characteristics of certified GA aircraft, remember that they have, during certification, demonstrated that their handling characteristics, including stall recovery, can be accomplished without the need for unusual pilot skill and attention (FAR 23.143)


....(b) It must be possible to make a smooth transition from one flight condition to another (including turns and slips) without exceptional piloting skill, alertness, or strength, and without danger of exceeding the limit load factor, under any probable operating condition ....
At certain amendment levels of 23.201 (stalls) power is not to be required during stall recovery (meaning you must be able to recover entirely power off). That said, nowhere in the requirements is there an objective to prevent altitude loss during a stall recovery. This notion seems to be a training thing. The idea that the application of power should be the first action to recover a stall worries me - what if the engine fails then?!

So the handling, and departure from controlled flight which may accompany an approach to stall, or actual stall in any configuration has been demonstrated during certification to comply with these requirements.

During certification stall testing, smooth air is desirable. If turbulent air is encountered during flight, including stalls, things can be very different.

In a Cessna 152/172/182/PA-28, landing configuration could be any configuration for which flight is possible (landing gear position as required, if applicable). The use of flaps, carb heat, propeller fine, cowl flaps are not required to accomplish a safe landing - just a good idea. Landing configuration need not be defined for a simple GA aircraft, it's about any configuration. If an instructor/examiner seeks a particular configuration, they should state it.

Yes, in a turning stall, the sudden application of lots of power can be destabilizing. This should be taught. If a pilot initiates a stall recovery at altitude, the application of a lot of power need not be necessary until the stall is recovered, as with lots of altitude, the pilot has some to spare to assure that stall recovery is less challenged. If the pilot has approached a stall at low altitude, and power is required during recovery, okay, the attempt should be made, but that pilot already has placed themselves into a precarious situation. Low altitude flight flight should not be out of control flight.

If a pilot wants to do a full stall in landing configuration, and they are well aligned with a suitable landing surface a few feet under them, very good!

tescoapp 16th Apr 2018 13:53


Stalls and recovery:
(i) clean stall;
(ii) approach to stall in descending turn with bank with approach configuration and power;
(iii) approach to stall in landing configuration and power;
(iv) approach to stall, climbing turn with take-off flap and climb power (single-engine aeroplane only)
That's the official line from EASA with what you should be able to do from COMMISSION REGULATION (EU) No 1178/2011 the number iv) was added in 2011
The TTTT thing has been going around for years and it gets perverted and changed, its not an official syllabus thing.

I think it was.

T turn
T time record the time you turned.
T forgotten that one might have been trim
T twist which was reset your DI so you didn't go off on some nonsense heading and get lost.

It might have been 5 t's, its bound to have come from some RAF CFS method and its raw form how it originally was worked a treat.

TheOddOne 16th Apr 2018 18:32

Well, now the following is taught:

T T T

being

Turn
Time
Talk

In other words, at the waypoint, focus entirely on the threat and error management of your turn on to your new heading
Then note the time
Once stabilised on your new heading (gross error checks and a FREDA carried out) tell whoever you've been talking to on the radio

sorry about the thread drift.

TOO

Vilters 16th Apr 2018 19:11

Well, I don't know the examiner who would ask such a thing.
STALL means STALL = Loss of speed and control.

Holding 75 kts is not going to get you anywhere "near" stall in a C-172 unless you are willing to pull the wings off the thing. => High "G" load.

And then, with Flaps. . Come on . . . Max "G" load with flaps is 2 G.

Flaps + holding 75 kts? => You can fly the tanks dry without ever getting "ANYWHERE" close to stalling.
You are AT LEAST 15 kts ABOVE a possible stall.
Add some power to that and you are 20 kts ABOVE stalling.

We used to fly a C-172 right into the stall, add power, add more power till at FULL power and cruise along at 30 kts indicated.
With only 2 on board and light on fuel, we could get to 27 kts IAS. Yeah, yeah, that poor horn blaring like a stricken goat. LOL.
It' called flying on the back side of the stall speed. Transfer weight from the wing to the powerplant.
Less weight for the wing to carry and the stall speed drops off to ridiculous values.

BALL centered at ALL times. That's the only "must do".

Gertrude the Wombat 16th Apr 2018 20:10


Originally Posted by Vilters (Post 10120534)
We used to fly a C-172 right into the stall, add power, add more power till at FULL power and cruise along at 30 kts indicated.

Done that in a 152. Heading into wind, of course, so that by looking at the ground we could see that we were flying backwards.

Pilot DAR 16th Apr 2018 21:06

My C 150, with a Horton STOL kit is capable of sustained flight, and 15 degree banked turns at 22 MPH indicated. However, when I installed a swiveling pitot head and second ASI, I found that the actual airspeed was 41 MPH. So that would be a case where the position error on the pitot tube was extreme, and the difference between IAS and CAS was huge. But, it's fun to look at 22 MPH, and think to one's self: "wow, that's slow!".

Careful doing that for sustained periods though, as the CHT gets hot, and could be damaging.

Crash one 17th Apr 2018 14:47

There are threads on here and next door that have people getting very hot under the collar regarding the use of the words "stall" and "speed" in the same sentence.
Especially among those who like to be upside down a lot.
Having said that "landing configuration" is the determining factor here, which usually involves being straight and level, reduced power, some flaps, flying slower than cruise speeds etc. Trying to stretch the glide without increasing power seems to cause the problems, so is unlikely to result in maintaining 75 knots on a 172.
At 75 knots and decending at 700fpm is never going to stall because the "landing configuration" including airspeed and rate of decent are maintained.
The only way to stall that is to raise the nose, reducing the speed and increasing the angle of attack.
Or have I just stated the bleeding obvious again?

NorthSouth 17th Apr 2018 16:30

Crash one, trouble is the bleedn' obvious clearly isn't.

One of the big problems is that "landing configuration" is rarely if ever actually flown. First of all the starting point should be Vref, i.e 1.3 x Vso adjusted for aircraft weight. Most light aircraft final approaches are flown at way higher than 1.3 x Vso.

NS

Genghis the Engineer 17th Apr 2018 18:05

If we are in the game of stating the obvious, could I wade in and point out that configuration and speed are two different things.

In any given configuration, there are a range of speeds ay which the aeroplane may be flown.

G

MarcK 17th Apr 2018 23:34

I would like to point out that Vs0 is "stall speed in landing configuration" (at least on my side of the pond) which, in a 172, means full flap. That's the bottom of the white arc. You may, of course, actually land using less flap. I think most instructors teach full flap landings, except when wind conditons suggest otherwise. Certainly, short field landings are full flap.

nkt2000 18th Apr 2018 11:46

I was taught to deal with stalls in the landing configuration when turn from base to final. I usually have two stages of flap at that time and leave the final stage until on final (if I use it at all, depending on the wind). I guess the learning outcome is to deal with stalling during bank with flap.

Crash one 18th Apr 2018 12:42


Originally Posted by Genghis the Engineer (Post 10121653)
If we are in the game of stating the obvious, could I wade in and point out that configuration and speed are two different things.

In any given configuration, there are a range of speeds ay which the aeroplane may be flown.

G

Quite right Gengis.
I think there is too much "airline jargon" applied to light aircraft ops.
If you have a 2000 metre runway and a 172, then "configuration" is not required.
With my Emeraude and 600 metres in a 10 knot wind, close the throttle and land.
As for 1.3 X Vso that amounts to 52 knots, I've had full control at 45 and don't have to backtrack quite so far.

scifi 18th Apr 2018 15:13

Hi Crash One... I don't see how the Approach speed has any connection with the distance of the Back-track. As long as you put the wheels on the tarmac, at the Piano Keys, at Vso, it doesn't matter two hoots what your speed was half a mile before.


There is one other anomaly, when we use the term 'speed over the fence'... It all depends upon where the fence is. For most of the airfields where I fly, the fence is 400 to 800 yards from the Threshold, plenty of space to loose many knots down to Vso. For pilots where the fence is at the threshold, they have to make some fiddle-factor adjustments.
.

tescoapp 18th Apr 2018 15:42

scifi "speed over the fence" is another airline term which is to do with landing performance.

Airliners are not mean to land on the numbers. The touchdown point is at a set distance down the runway with a nominated angled path down to it. When you are on this path then when you go over the threshold you will be at a specified height. This is referred to as the fence.

For departure there are also fences for take off performance which depend on if the runway is wet or not.

I have not on purpose given any hard numbers for these "fences". Like the 1.3 VSo which is also a airline reference speed number it isn't relevant to SEP aircraft.

It doesn't have anything to do with a physical fence on the airfield.

Pilot DAR 18th Apr 2018 16:26


As long as you put the wheels on the tarmac, at the Piano Keys, at Vso, it doesn't matter two hoots what your speed was half a mile before.
Speed awareness and control is a pretty important task for a fixed wing pilot, especially in more high performance aircraft. Yes, some aircraft could be safely slowed from excess speed a half mile back, in other types this would destabilize the approach to be unsafe.

I remember once, in very early days, landing a 182 on an 11,000 foot long runway. I allowed it to contact the ground much too fast (two hoots shortage on my part). What a bucking bronco ride that was! Now, for me, all tricycle type landings will be full or near stall at the time of surface contact.

My half mile back speed will be planned and executed. The place of landing and approach path may affect my decision, as well as the possibility (or reality) of engine failure, and the affect on other traffic of what could be a non standard approach.

On this landing, I was flying the approach to the knot, 1.1Vso, as I had only 40 more feet of runway length available than that required for the aircraft under those conditions.


Piper.Classique 18th Apr 2018 19:34

Interesting points of view here. I wonder how many of the posters have actually stalled their aircraft in the configuration of the day, as it were? Independent of this thread, I spent an hour yesterday in a homebuilt, investigating behaviour at the stall in different configurations.
No flight manual, we are about half way through a fifteen hour program intended to give us the information we need to write one. I'm flying at a fairly light weight, between full and half tanks, solo in a two seat aircraft. Probably fairly representative of the use it will get. It's interesting to reflect on all the different possibilities there are. At this weight, Clean power off, clean at different power settings (1700 rpm, 2100 rpm, and 2450 rpm) Flaps 15 power off, 1700 rpm, and 2100 rpm. I'm not intending to try 2450 with any flap, we've set a flap limit speed based on similar types, and don't really want to bust it. Then there is Flaps 30, all the above, turns at different angles of bank with and without flap and power.
Then do it all again at different weights. I suspect all the DGAC really want is clean and
full flaps, but I'm having fun.

The hard part so far has been getting decent enough weather. The first flights were done in march, then we had three weeks waiting for the rain to stop and the runway to dry out.

I think I could easily spend all fifteen hours in upper air work and enjoy doing it. The speeds are actually predictable, once the clean stalling speed at a given weight is established. What is interesting is the way the aircraft signals that it is unhappy, and what happens at the point of stall. It's making my flying a lot crisper, for sure.


Does anyone know an easy way to measure takeoff distance to 15 metres? We are supposed to come up with that, at some point. At MAUW. Runway surface and wind not specified, which seems to make it a bit pointless, to my mind.

Genghis the Engineer 18th Apr 2018 21:16

Piper - I don't know what your relevant experience is, nor what you're testing - but DAR and I have both spent significant portions of our lives doing that sort of testing for a living. I'm certainly very happy to share what wisdom I have, and I've never known him to be unwilling to open up and share his experience either.

Here's one way of doing take-off and landing distances, although nowadays we'd mostly use recording GPS...

http://bura.brunel.ac.uk/bitstream/2...oJ%20final.pdf

If you want to email be at boffin at engineer dot com, I'd be happy to set up a 3-way email conversation.

G

scifi 18th Apr 2018 23:02

Hi GtE, I wonder how you factor in height asl in those calculations ?

Our flying club had recently fitted a new propeller to a C152, so myself and my passenger took it out to see if we could find any performance increase. We climbed to about 10,000ft where we found it just ran out of lift.. 50ft/min was all it would do. Pull back on the stick and it would descend (-300 f/m.).. Push forward and it would descend, any angle of bank and it would descend..
Whether this could be called a stall I don't know, but there was only one stick position that would give us a climb.... The engine was leaned out for max rpm, which I think was about 2300 rpm. The Indicated airspeed was about 60 knots. At a rough guess we would have run out of fuel before it would climb another 1000ft.


.

Crash one 18th Apr 2018 23:56


Originally Posted by scifi (Post 10122786)
Hi Crash One... I don't see how the Approach speed has any connection with the distance of the Back-track. As long as you put the wheels on the tarmac, at the Piano Keys, at Vso, it doesn't matter two hoots what your speed was half a mile before.


There is one other anomaly, when we use the term 'speed over the fence'... It all depends upon where the fence is. For most of the airfields where I fly, the fence is 400 to 800 yards from the Threshold, plenty of space to loose many knots down to Vso. For pilots where the fence is at the threshold, they have to make some fiddle-factor adjustments.
.

I fly from a 600metre grass strip. There is no fence at the 24 end, just a footpath then a barley field. 06 has trees ~100metres short of the strip with a rough "grass" area between. I don't have a particular "threshold" speed other than controllably above the stall, approach speed is adjustable to suit the eyeballed rate of decent, radius of final turn, distance from threshold etc. If I can put it down very close (10metres in) to the threshold at 45knots I can get it stopped by 100metres in. If I go for 1.3Vso (52 knots) I'll end up at 250 metres in. I don't like using the brakes cos I don't have a safety wheel on the front and prefer to keep the prop out of the mud!

Pilot DAR 19th Apr 2018 03:32


50ft/min was all it would do. Pull back on the stick and it would descend (-300 f/m.).. Push forward and it would descend, any angle of bank and it would descend..
Whether this could be called a stall I don't know, but there was only one stick position that would give us a climb
Yes, you ran out of a combination of lift and power (more of either, and you could have climbed more). You reached the service ceiling. If there were any stick position at which any climb was possible, the aircraft was not stalled yet. When you reached a higher altitude, and the stall horn was screaming to simply maintain altitude, you are near the absolute ceiling, and the stall. I have done this during flight testing in a Cessna 185 with a carburetted engine, on auto fuel. 20,800 feet. I could get to 21,000, but could not stay there, it would settle back stalled a few hundred feet. There are atmospheric corrections to reduce this to standard atmosphere if needed. If the service ceiling you obtained in the 152 with a new prop was 10,000 feet, I would not be very enamored of that prop.

Piper.Classique 19th Apr 2018 05:16

Thank you G t E. I'll get an email off to you later today.

Genghis the Engineer 19th Apr 2018 07:19


Originally Posted by scifi (Post 10123254)
Hi GtE, I wonder how you factor in height asl in those calculations ?

Our flying club had recently fitted a new propeller to a C152, so myself and my passenger took it out to see if we could find any performance increase. We climbed to about 10,000ft where we found it just ran out of lift.. 50ft/min was all it would do. Pull back on the stick and it would descend (-300 f/m.).. Push forward and it would descend, any angle of bank and it would descend..
Whether this could be called a stall I don't know, but there was only one stick position that would give us a climb.... The engine was leaned out for max rpm, which I think was about 2300 rpm. The Indicated airspeed was about 60 knots. At a rough guess we would have run out of fuel before it would climb another 1000ft.


.

Let's get this straight?

You are trusted, with a passenger, to do an air test on a prop change and have excellent recall of numbers I'd have to look up in my post flight report, not to mention the relatively obscure concept of leaning for best power, but don't know about stalling in the landing configuration? I see why some people think you're a troll.

You clearly do have enough knowledge to look this stuff up in the same textbooks I've got on the shelf. Try this one... which has served me very well since I was an undergrad 30 years ago.

G

alex90 19th Apr 2018 07:41

I think the issue here is knowing what the term means.... perhaps it just got lost in translation somewhere?

Landing configuration generally means, gear down, normal stage of flaps for landing, air brakes if fitted etc... NOT descending at x ft per min maintaining y kts, or z rpm!!

Its all about terminology. I am sure that the OP has done these, but perhpas under a different name.

Piper.Classique 19th Apr 2018 18:40

The fence isn't, or doesn't have to be, a real fence. It's sometimes called screen height, and it's 15m high. If it was there it would be anyway. It's used in performance calculations. Take off consists of ground roll and an airborne sector. Would you believe to 15m?
Landing consists of an airborne sector which involves clearing a probably imaginary 15m fence, and touching down, followed by a ground roll. If you look in a flight manual for pretty much any light aircraft you should find all four of these distances given, and a factor to apply for different surfaces and wind conditions, altitude above sea level, and temperature.
Does that help?
Approach speed is also given, normally for MAUW. The takeoff and landing distances are calculated for the technique stated in the flight manual. Use something else and you are a test pilot.

150 Driver 19th Apr 2018 20:08

I've come to this thread a bit late, but isn't the purpose of training to deal with a 'stall in the landing configuration' all to do with dealing with the aftermath of a mistake - which would be letting the speed decay away whilst close to landing. eg base to final turn or loss of concentration on final.

In other words you've set the plane up for landing (full flap, little or no power), you're less than a thousand feet above the ground, you f--k up, are you going to die or not ?

So by its very nature you're likely to be flying at 30, 40 or 50 knots. Testing this at 80 knots seems utterly pointless .

Pontius 20th Apr 2018 03:55


Hi GtE, I wonder how you factor in height asl in those calculations ?
If only there was a term for such a measurement :hmm:

Piper.Classique 20th Apr 2018 10:55


Originally Posted by Pontius (Post 10124614)
If only there was a term for such a measurement :hmm:

Tee Hee. Pontius, that was naughty.

Sir Niall Dementia 20th Apr 2018 12:59


Originally Posted by scifi (Post 10122786)
Hi Crash One... I don't see how the Approach speed has any connection with the distance of the Back-track. As long as you put the wheels on the tarmac, at the Piano Keys, at Vso, it doesn't matter two hoots what your speed was half a mile before.


There is one other anomaly, when we use the term 'speed over the fence'... It all depends upon where the fence is. For most of the airfields where I fly, the fence is 400 to 800 yards from the Threshold, plenty of space to loose many knots down to Vso. For pilots where the fence is at the threshold, they have to make some fiddle-factor adjustments.
.

:ugh::ugh::ugh::ugh: If you're not a troll you have a strong urge to become a statistic! Windshear? Engine failure on short final? insufficient braking action? A stable speed on finals gives a huge protection from all of the above. My day job involves stable approaches every time, as far as possible I do the same in my spare time. My aeroplane is a basic permit beast, but she's mine, she cost me good money and I like to protect her, me and anyone who flies with me.

SND

Crash one 21st Apr 2018 12:46

Troll "simulated glide path" my ass!

Sir Niall Dementia 21st Apr 2018 14:08

Looking around his other posts, possibly a keen aero-modeller with a sim package on his pc. Probably a teenager, a lot of his posts are similar to CapA330.

SND

funfly 21st Apr 2018 20:15

This is all getting a bit technical.
Surely all the person wanted to see was how you reacted to being too slow on finals, with all the inherent dangers.
What you actually call it is irrelevent, however its important that you recognise the situation if it happens and that you can handle it.

Gertrude the Wombat 21st Apr 2018 20:28


Originally Posted by funfly (Post 10126189)
Surely all the person wanted to see was how you reacted to being too slow on finals, with all the inherent dangers.

Low and slow on final? - shove the nose down, instinctive reaction. (And also probably add some power.) Always pleases instructors, who seem to come across other behaviours from time to time?

tescoapp 22nd Apr 2018 06:55

Very common to hold the attitude and power out of it. Which is still being taught in the USA and all over Europe.

As its normally recovered from the none stalled, stall warning stage it works mainly because nobody is that great at holding an attitude. But there is also a possibility of the nose pitching even further up.

And its not just a SEP PPL thing, it goes all the way to type rated machines and pro pilots.

Stalling was done in type ratings but after that it wasn't given that much priority in training. In fact I don't think I did a stall for 10 years. EASA have now included it in the normal training cycle exercises along with upset training. So in a 3 year cycle you get 12 sim sessions and all the stalls are covered. The new pilots on there first SIMs after TR do revert back to SEP training and this causes quiet a few repeats. Habits formed in basic training are extremely hard to unlearn.

The other one which is seen a lot is full rudder to lift the wing in case of wing drop. Instead of rudder to stop yaw and aileron to bring the wing back to level. It really gets acrobatic when people use both aileron and rudder at full deflection to recover especially if the stick shaker then triggers they hammer the power leavers forward and then the over speed warner sounds. Then they lift the nose... In upset training you can have a 10 knot window between stall and over speed. Its thought that the common exercise of flying slow and using the rudder to keep the wings level and change the heading is root cause of this in Europe. USA until the airbus tail falling off just after 9/11 it was standard practise.

Pilot DAR 22nd Apr 2018 12:14

At the basic, the risk of a stall exists when the angle of attack is too high. The best way to reduce the risk of stall, is to reduce the AoA. If an aircraft manufacturer recommends powering out, that is theirs to do, but pilots should always remember basic principles.

tescoapp 22nd Apr 2018 12:36

No OEM that I am aware of recommends powering out.

It seems this powering out is pure pilot nonsense.

Tankengine 22nd Apr 2018 12:58


Originally Posted by tescoapp (Post 10126748)
No OEM that I am aware of recommends powering out.

It seems this powering out is pure pilot nonsense.

Unless you are too low to lower the nose too far! ;)

tescoapp 22nd Apr 2018 13:59

Yep that's the logic of the pilot nonsense.

You can't unstall an aircraft without reducing angle of attack. You only have to lower it a degree for you to unstall.

Ga aircraft do not have the power to defeat the induced drag of a stalled aircraft. If your that low that your going to hit the deck with the nosewheel first if you reduce the attitude you might as well hold it as it is and accept the arrival. Aka a short field on the horn landing with no flare and cut the power on touchdown. I suppose that isn't taught any more.

So the excuse for powering out is based on a stall in the last 10 feet of the approach. It wouldn't work anyway on a stalled aircraft.

Which leads into the approach profile are they flat 3 degree and powered up or are they doing a sensible single engine approach steeper with less power.

The ones usually advocating powering out are usually the ones with + huge amounts of speed extra. It's probably linked with all the hassle with power outs and hanging in the air doing a tap dance on the rudder while the engine thrashes itself and nothing much happens until they actually fail holding the attitude and the plane unstalls itself despite their intentions.


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