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darien-l
30th Jan 2011, 17:21
I just had a fairly close call on a go-around in a Grumman Cheetah during a full-flap landing on a 3000' runway with some trees, houses, and power lines just past the far end. I came in high and fast, floated, and applied full power for a go-around. The plane took forever to accelerate from 50 to 65 KIAS in ground effect, and when it finally did, the climb rate was minimal, and I barely cleared the obstacles. By the time I had any positive rate of climb to speak of, I didn't want to touch the flaps for the fear of sinking right into the obstacles. However, the Cheetah POH recommends the following go-around procedure:

"Should a landing be balked, apply full power immediately; carburetor heat OFF; establish a positive rate of climb at 60-65 KIAS (69-75 MPH); retract the flaps and trim for normal climb."

So my question is, is there anything I could've done better? My suspicion is that I should have ignored the procedure recommended in the POH and retracted a notch of flaps immediately after application of full power, without waiting for positive rate of climb. Thoughts?

A pumps
30th Jan 2011, 17:26
What was the max landing weight of the aircraft and what was your actual landing weight.

What did the landing performance calculation suggest ?

Was there a tailwind present?

Rgds

trex450
30th Jan 2011, 17:42
Did you reduce the flap from full to take off after applying full power? On applying full power you should reduce flap to the take off setting then wait for the speed, and climb, before retracting the flaps altogether.

darien-l
30th Jan 2011, 18:00
> What was the max landing weight of the aircraft and what was your
> actual landing weight.

Max landing weight: 2200 lbs.
Actual landing weight: 2110 lbs.

> What did the landing performance calculation suggest ?

Wouldn't a take-off performance calculation be more appropriate for go-arounds? The POH only has take-off performance charts for the recommended flap setting (no flaps) so it doesn't directly apply here.

Anyway, the landing performance table shows that there was plenty of room for me to safely land; I only needed ~1000' of the 3000' runway, but as I said before, I came in too high and fast, and decided to go around.

> Was there a tailwind present?

It was pretty much a direct cross-wind landing: cross-wind component was about 11 knots, and tailwind component was only about 1-2 knots.

> Did you reduce the flap from full to take off after applying full power?

No, I did not, because the POH recommended waiting for positive rate of climb before messing with the flaps.

> On applying full power you should reduce flap to the take off setting
> then wait for the speed, and climb, before retracting the flaps
> altogether.

The recommended take-off setting is no flaps, so I don't think that would work too well. However, I think that going from 30 to 20 deg of flaps immediately after application of full power may have been the thing to do. Are there any safely issues with doing this while still in ground effect, such as the plane dropping the nose and crashing into the runway?

Big Pistons Forever
30th Jan 2011, 18:48
All of the Grumman series have a simple flap (ie no slot or fowler action). All they do is generate drag so they should be fully retracted after full power is applied and the airplane has started climbing.

Also the Grumman series demand accurate flying to achieve the desired climb performance. Vx for the Cheetah is 68 kts and a speed even a few knots slow will have a marked impact on performance.

Not saying this was the case for you, but I have noticed a lot of pilots, when conducting a near the runway low speed go around, allow the nose to pitch up as the power is applied. This causes the aircraft to climb out of ground effect while still at a very low airspeed and results in an excessively long period where the aircraft is only very slowly accelerating to Vx. The tendency then is to hurry the climb at too low an airspeed which only makes things worse. You have to the discipline to hold the aircraft in a level attitude in ground effect (ie no more than 15 feet above the runway) until the airplane accelerates to it Vx before starting to climb.

trex450
30th Jan 2011, 18:59
I confess I know nothing about the AA5 series but am familiar with cessna singles. The landing flap setting gives lots of drag, while it would be daft going from full flap to nothing on applying power and commencing the go around it makes a lot of sense to reduce the flap to the intermediate setting to reduce the drag therefore increasing your acceleration. The 172 that I fly has a landing flap setting of 30 degrees and recommended take off of zero flap unless operating from a soft/short field. In the case of a go around after applying full flap in the cessna I would reduce to 20 degrees immediately then 10 degrees as the speed is increasing and then zero once a climb is established and the speed is safe.
Unless you have lots of excess power then it is going to be very hard to accelerate (an climb) without getting rid of the drag flap settings.

Kerling-Approsh KG
30th Jan 2011, 19:07
Big Pistons, I often enjoy your posts and agree with you. On this occasion I don't, because you generalise too much.

The procedures in the Grumman POH have undergone some kind of scrutiny (I wouldn't like to say how much, but they passed the FAA's tests) and they are the published procedures for the aircraft. They are the procedures by which, by law, the aircraft must be flown, and they are the procedures which, if followed, achieve the relevant safety standards.

The OP says he came in high and fast, yet he left the go-around until the last minute, it seems. That's a learning point for him. He handled the aircraft through the event without accident and probably learned about handling from that.

The AA5 is a wonderful training aircraft. Anyone can fly it, almost anyone can land it (they really made a mess of designing the nose landing gear), but a decent examiner or instructor can tell in the shortest time how skilled the student or candidate is. I loved instructing on them, and flying them myself, because flying them well requires skill.

darien-l
30th Jan 2011, 19:34
Thank you for the comments, everyone. The recommended go-around procedure in the Grumman AA-5A POH (Full power immediately; carburetor heat OFF; establish a positive rate of climb at 60-65 KIAS; retract the flaps and trim for normal climb) still does not make sense to me, for the following reason: say I was operating at a higher density altitude than I was, and was unable to leave ground effect with full flaps down. If I were to follow the procedure verbatim, I would stay in ground effect until I crashed into the obstacles at the end of the runway.

It appears that most people here are in agreement that it's OK to retract at least one notch of flaps while still in ground effect. If anyone sees this as a serious safety issue, please speak up.

Kerling-Approsh KG
30th Jan 2011, 20:07
Yes, I do. I think you ended up in a situation beyond your training and which the aircraft was not tested for. Avoid that situation in future, and always remember, the moment you step aside from the proscribed procedures for any aircraft two things happen: first, you become exclusively responsible for the outcome and second, you enter uncharted, and possibly unexplored, territory at your peril.

If you fly the aircraft correctly, you shouldn't need to experiment.

Next time, fly the approach properly or go around early enough for it not to be an issue.

I agree that there are some interesting things about the AA5A at low speeds; in testing, erroneous airspeed calibration sometimes proved to be problematic, but it's no DC8, and nor does it need handling like one.

Final thought... Think about what would happen if you could try taking various AA5As to a safe altitude. Establish the 1g flap full stall speed iteratively, and then go to that speed plus 3 knots and retract some flap. The pitching moment and wing drop may be significant, and that's a good reason to achieve a safe margin above the stall speed for the configuration you're about to adopt before adopting it. I mention this even though in ground effect it will be different, but testing in ground effect is difficult and hazardous, and therefore usually done in tunnels or by modelling.

darien-l
30th Jan 2011, 20:20
Kerling-Approsh KG: While I appreciate your feedback, I think that whether I should have gone around sooner is a totally separate issue from the one I'm trying to address here. (Short answer, which I knew myself before I posted here: yes, I should have.) Still, there are obviously many other go-around scenarios that involve application of full power a few feet above the runway. Your take on it is to always follow the POH to the letter and wait until positive rate of climb before retracting flaps. I accept your position, but I have encountered enough situations where the POH procedures were not optimal, so I'd like to solicit more feedback from pilots who are familiar with the Cheetah, and see what their take on it is.

old-timer
30th Jan 2011, 20:39
I confess to no knowledge of AA5; However my approach is a simple one effective for all types;

(NOTE - I.M.H.O in panic sitations anything complicated or too detailed just doesn't work but I am a basic type Human MK 1 & not PERFECT BY ANY STRETCH OF THE IMAGINATION)

Here tis'

1) Apply full power IMMEDIATELY :ok:

2) Retract drag flap IMMEDIATELY :ok: - BUT NOT LIFT FLAP :=

3) Pray for effective R.O.C :ok:

4) Thank god for power of prayer ref' Item 3 ! :D

5) In the event of items 1,2 & 3 non-effectivness tighten belts & brace for impact ! :eek:

Take care folks - tis' better to be a pilot of extreme skills & knowledge & even better to not be in a situation requiring use of such extreme skills & knowledge in the first place - if at all possible.

Big Pistons Forever
30th Jan 2011, 20:48
I confess I know nothing about the AA5 series but am familiar with cessna singles. The landing flap setting gives lots of drag, while it would be daft going from full flap to nothing on applying power and commencing the go around it makes a lot of sense to reduce the flap to the intermediate setting to reduce the drag therefore increasing your acceleration. The 172 that I fly has a landing flap setting of 30 degrees and recommended take off of zero flap unless operating from a soft/short field. In the case of a go around after applying full flap in the cessna I would reduce to 20 degrees immediately then 10 degrees as the speed is increasing and then zero once a climb is established and the speed is safe.
Unless you have lots of excess power then it is going to be very hard to accelerate (an climb) without getting rid of the drag flap settings.

This comes down to knowing your aircraft and of not using one size fits all procedures that unfortunately seems common at flight schools. Cessna's have a large area increasing slotted fowler flap, Grummans have small simple hinged flap. They are different aircraft and what works best on a Cessna may or may not (as is the case in this example) be relevent to Grummans. Incidently the max lift position for a C172 is 10 deg's of flap which is why the POH specifies that in the event of a balked approach (go around) the flaps should be immediately raised to 20 degs. but then adds retract to 10 degs until obstacles are cleared which in practice means you will usually just keep going from 40/30 to 10 degs. In any case the the POH procedure should be the one followed not some locally developed "better" one.

Kerling-Approsh KG
30th Jan 2011, 20:51
Darien, aircraft are certified to fly within an envelope. For example, the elevator on a twin-jet with underslung engines is the size it is, to cope with a full thrust go-around at Vref-5 knots. Slower than that, and there is no guarantee of the aircraft being controllable (read the report on the Turkish B737 crash at Schiphol if you need to see a practical outcome of this). Similarly, your AA5A is certified within limits, and your job as the pilot is to stay within those limits. Within those limits, the procedures in the POH should be good. Outside those limits, they may not be, and that's where your problems began. Hence why it's so important to stay within the envelope.

You mention that you've encountered several situations in which the POH procedures were not optimal... If true, you should consider finding some high quality training or re-training. That shouldn't be happening (the number of times it's happened to me in several thousand hours of flying, training, testing pilots and testing aircraft is very small).

Old-timer, would you be so kind as to describe how one might define 'drag flap' and 'lift flap' on a particular aircraft, please? None of the training I've received, nor the text books I have on design, certification, testing, or aerodynamics are any help.

Big Pistons Forever
30th Jan 2011, 20:55
Thank you for the comments, everyone. The recommended go-around procedure in the Grumman AA-5A POH (Full power immediately; carburetor heat OFF; establish a positive rate of climb at 60-65 KIAS; retract the flaps and trim for normal climb) still does not make sense to me, for the following reason: say I was operating at a higher density altitude than I was, and was unable to leave ground effect with full flaps down. If I were to follow the procedure verbatim, I would stay in ground effect until I crashed into the obstacles at the end of the runway.

It appears that most people here are in agreement that it's OK to retract at least one notch of flaps while still in ground effect. If anyone sees this as a serious safety issue, please speak up.

The Grumman flaps are not very big or very effective. If you cannot accelerate in ground effect with the flaps down you almost certainly won't be able to accelerate in ground effect if you retract the flaps, so if you find yourself in this position your only recourse is to close the throttle and take your lumps straight ahead. In my experience the POH procedure works just fine and should be followed. Rather than messing with the flaps immediately after applying full power I would suggest you concentrate on accurate attitude control to stop the aircraft from climbing until it has accelerated to Vx.

Kerling-Approsh KG
30th Jan 2011, 21:02
Big Pistons, I enjoyed your last post there. Only clarification would be, which Vx? If I bought an aircraft, or flew it regularly and had time to kill one day, I would go and test it and establish the correct values of Vs etc and then all the others that follow, including the climb speeds, but I think it would be better for our original poster to use the POH figures, which should be conservative at <MTOW or MLW.

darien-l
30th Jan 2011, 21:19
Right, Vx is lower with full flaps; Cheetah POH recommends 60-65 KIAS.

In terms of the POH procedures not always being optimal, here's an example pertaining to flaps on the Cheetah: the POH recommends no-flap takeoffs, but I was told by several Cheetah owners to take off with 10 degrees of flaps for best ROC, and have verified this myself. More generally, I guess I was trained to treat the POH as a recommendation rather than a Bible, and speak to the actual people who fly that particular airplane a lot to find out what works best.

Big Pistons Forever
30th Jan 2011, 21:40
Right, Vx is lower with full flaps; Cheetah POH recommends 60-65 KIAS.

In terms of the POH procedures not always being optimal, here's an example pertaining to flaps on the Cheetah: the POH recommends no-flap takeoffs, but I was told by several Cheetah owners to take off with 10 degrees of flaps for best ROC, and have verified this myself. More generally, I guess I was trained to treat the POH as a recommendation rather than a Bible, and speak to the actual people who fly that particular airplane a lot to find out what works best.

The POH procedures were developed by the manufacturers own engineering test pilots. I think it is highly unlikely that your average PPL (or CPL instructor for that matter) will have the knowledge and experience to only take them as a "recommendation" and be able to deviate from them with a "better" way that replaces the POH procedure.

You say you have "verified" that the airplane has a better ROC with 10 deg flaps. So that means you used a calibrated test instrumentation set up and flew enough takeoff profiles to generate sufficient test data that it could be extrapolated to all air density conditions ?

I am guessing you have decided you "feel" the aircraft climbs better on the basis of the power of suggestion of an airport urban myth.

It's simple, when in doubt follow the POH :ok:

darien-l
30th Jan 2011, 21:55
All I can say is that with 10 degrees of flaps, ROC as measured by VSI is about 100 fpm better in my typical flight environments. Aviation Consumer, as well as the AA-5 owners I've spoken to, say the following:
"Takeoff and climb performance can be enhanced by ignoring book procedures, which call for flaps up. Some experienced Tiger/Cheetah pilots put down about one-third flaps when takeoff performance is critical."

http://www.randyarmadillo.com/flying/tiger/Aviation_Consumer_1_1.pdf

BestAviation
30th Jan 2011, 22:31
In terms of the POH procedures not always being optimal, here's an example pertaining to flaps on the Cheetah: the POH recommends no-flap takeoffs, but I was told by several Cheetah owners to take off with 10 degrees of flaps for best ROC, and have verified this myself. More generally, I guess I was trained to treat the POH as a recommendation rather than a Bible, and speak to the actual people who fly that particular airplane a lot to find out what works best.

This is how pilots get themselves killed I'm affraid. Although I agree that taking everything in aviation at face value is an equally dangerous game I would vet my sources carefully when it comes to other peoples ideas on what works and what doesn't. Over the years I have heard (and sometimes had recited to me from convertees) some very convincing and equally BS stories told by "authorative" "senior" pilots (and even instructors) without a clue what they were talking about.

As mentioned in another post - the POH was developed by the (actual) people who created and tested the aircraft, and one should assume they know more about the aircraft than most owners combined. As for the use of flaps, or no flaps, I'm sure every imaginable scenario was test flown and graphed before the aircraft was certified.

I admire pilots like darien-I who after having had a problem reach out to learn more about what he/she could have done different. Those are qualities that makes a pilot better. :D

However, as none of us were there with you and we don't really know how you fly I would advice you find an instructor - preferably one that believes in POHs and knows the Cheetah - and go do some practise circuits with go-arounds. Or go practise some yourself, either from a safe altitude away from the airport, in the ciruit but from a higher go-around height, or at a runway with adequate remaining runway lenght so you don't hurt yourself in the process should you not achieve a good ROC.

Your reason for the close call can be many and doesn't necessary relate directly to any procedure in the POH. Even following a POH procedure can get you hurt if it's not done in a timely and accurat manner.

Big Pistons Forever
31st Jan 2011, 00:16
All I can say is that with 10 degrees of flaps, ROC as measured by VSI is about 100 fpm better in my typical flight environments. Aviation Consumer, as well as the AA-5 owners I've spoken to, say the following:
"Takeoff and climb performance can be enhanced by ignoring book procedures, which call for flaps up. Some experienced Tiger/Cheetah pilots put down about one-third flaps when takeoff performance is critical."

http://www.randyarmadillo.com/flying/tiger/Aviation_Consumer_1_1.pdf

Went out and tried it this afternoon (albeit in my AA1B, not in the Cheetah). As far as I can see there was no difference in climb rate. If there was any change in ROC it would have been negative. The one thing I did notice is the aircraft climbed with the nose lower as compared to the flaps up climb. One thing I noticed Cessna /Piper drivers find disconserting is that you need to get the nose up to the Vx attitude to get the aircraft climbing. Cessna's are much more forgiving in this sense as they will climb OK in a fairly wide range of nose up attitudes. This is not the case in the Grummans. You have to go quickly to the correct attitude and hold it. I think this is were the flaps 1/3 climb came from. It feels better and is a bit easier to hold so pilots get more performance when using flap. Nevertheless I still believe the POH recommended procedure should be followed in order to get the best possible performance.

DALMD-11
31st Jan 2011, 01:46
For What It's Worth:
Here's what the AA-1A Owners Manual says:

Balked Landing:
1. Apply full throttle
2. Carburetor heat; OFF
3. Establish climb attitude
4. Flaps: Retract, after accelerating to a safe airspeed

Now, it doesn't say exactly when to retract the flaps, but on page 18, the manual does say that the best angle of climb speed (Vx) with full flaps is 70 mph. Vx with flaps retracted is 75 mph.

FI_JOB_HUNTER
7th Feb 2011, 18:02
DRAG FLAP CONCEPT:
Flaps have two uses, reduce the stall speed (increasing the Clmax) and increase the Descend Path Angle (increase the Drag).... and to increase the forward visibility ok maybe more than 2 uses....

Drag flaps are called to those which only increase the Cd and not the Clmax or very slightly, thus not reducing the stall speed.
Only used to decelerate the aircraft speed not to land slower...

You don’t have to go through the Roskams to find that, I don't recall seeing this term in any book other than PPL text books.

BTW most of the flaps increase the Drag and because of that the ROC is decreased. So for me accelerate over Ground effect and at least retract the full flap one notch will make sense generally.

No offense intended in the vage definition and I stand to be corrected.

Pull what
11th Feb 2011, 13:26
A 'minimal climb rate' is a positive rate of climb! You should have retracted the flap as soon a rate of climb was detected.

SNS3Guppy
11th Feb 2011, 22:40
The procedures in the Grumman POH have undergone some kind of scrutiny (I wouldn't like to say how much, but they passed the FAA's tests) and they are the published procedures for the aircraft. They are the procedures by which, by law, the aircraft must be flown, and they are the procedures which, if followed, achieve the relevant safety standards.

There is no "safety standard," nor is there minimum performance prescribed. It's a Part 23 airplane. It's not a transport category aircraft certificated under Part 25. Don't expect the repeatability, or any climb or performance guarantees. The information in the aircraft flight manual is mostly interpolated, applicable to one airplane during tests, and wasn't all demonstrated. Only some of it was demonstrated, and the rest interpolated. Don't get too carried away with the flight manual in a light airplane, believing published numbers or performance values, because there's a high probability that your airplane won't achieve it.

One is NOT obligated by law to follow the procedures prescribed in the aircraft flight manual. They are not limitations.

The subject in question in this case is establishment of a positive climb before retracting flaps. Establishing a positive climb isn't necessary; achieving a safe speed prior to flap retraction is necessary. The amount of climb required is contingent on what the pilot elects to make necessary. If one intends to climb over a large obstacle, one might seek best angle. If one doesn't intend to climb, one might not climb at all. If one intends to climb to pattern altitude, one might seek best rate of climb. One might seek a different climb on a hot desert day, for cooling. The important aspect is achieving a safe airspeed prior to flap retraction.

As mentioned in another post - the POH was developed by the (actual) people who created and tested the aircraft, and one should assume they know more about the aircraft than most owners combined.


The aircraft was certificated to a lower standard, depending on when it was made, and that standard (Part 23) doesn't set a requirement for guaranteed performance. One should make no such assumption.

As for the use of flaps, or no flaps, I'm sure every imaginable scenario was test flown and graphed before the aircraft was certified.

Bad assumption. Aside from the fact that much of the performance data in Part 23 aircraft flight manuals is interpolated, one should note that the data should not be considered repeatable, and is not guaranteed. Every number in the performance section of your AFM/POH/AOM wasn't determined by actually performing and demonstrating that value, and one shouldn't assume that what did occur in the demonstration airplane will occur in your airplane.

Old-timer, would you be so kind as to describe how one might define 'drag flap' and 'lift flap' on a particular aircraft, please? None of the training I've received, nor the text books I have on design, certification, testing, or aerodynamics are any help.

Some posters here have confused flap types and don't seem to understand that performance is aircraft-specific. None the less, in many light airplanes, small amounts of flap contributes to lift far more than drag, while greater flap settings contribute little to the coefficient of lift, but represent a rapid rise in induced (and parasitic) drag.

You asked about a particular airplane. Several posters have addressed Cessna single engine airplanes, which are a better example than the Grumman Cheetah. At early flap settings (eg, 10 degrees), lift is enhanced with very little increase in drag. For short/rough field operations in a Cessna 206 (without a STOL kit), a very handy way to establish takeoff flaps is to fully deflect an aileron, then match the flap to the aileron. The aircraft flight manual won't tell you this, but after ample hours and years doing back country work in 200 series Cessnas, I can tell you it's a common technique that works very well.

Then again, another example I use often regarding fallibility of manufacturer procedures involves the fuel flow fluctuation procedure in the same airplane. Following the manufacturer procedure can cause an engine failure or prevent the engine from being restarted if it happens to quit during fuel flow fluctuations. Understanding the airplane and the systems will make clear why this is.

So my question is, is there anything I could've done better?

Yes. Go around sooner. If you're too close to an obstacle when you go around, you may not be able to climb over it.

Never overlook an opportunity to go around the obstacle. You don't necessarily need to go over it. It's far better than running into the obstacle.

My suspicion is that I should have ignored the procedure recommended in the POH and retracted a notch of flaps immediately after application of full power, without waiting for positive rate of climb. Thoughts?

If you had the safe speed to do so, why not? You already indicated that you were "fast." The issue is getting fast enough to retract flaps.

Consider your options here. Can you climb over or go around the obstacle with flaps extended? If so, then who cares if you ever retract the flaps? The obstacle is your overriding concern. Forget procedure, forget practices, forget flaps. Think obstacle. If you can go around the obstacle, then you're golden.

If you can't get over or around the obstacle with flaps extended, are you going to be able to get the flaps retracted and do make it around or over the obstacle? If so, then you're golden.

If you're too close to the obstacle to get over or around, then you've put yourself in a position from which there may be no extrication. In this case, you're going to need to do your best to seek a favorable outcome. Try to get stopped on the remaining runway. Try to hit something inexpensive. Try to put the fuselage between two trees to let the wings take the impact. Try to land on a road, field, parking lot, golf course, or lake. Do something to negotiate the best outcome for you.

Monitor your approach and if you see it going badly, try to go around sooner.

Piltdown Man
16th Feb 2011, 20:54
Mr Guppy - Is there a book with your name on? I there was I'd (even buy it and) read it. No, I'm not being sarcastic, I just find myself learning rather a lot from your posts.

PM

JammedStab
10th Apr 2015, 05:12
Get rid of some of that drag and reduce the flap setting. If the speed is slow, do it in level flight and then you can start accelerating after which you can start climbing after which you can reduce some more flap, etc,

You have way more drag reduction by reducing the last 25% of flap travel than loss of lift. There was no stall warning mentioned so increasing the stall speed by the 1 knot or so by reducing your flap setting is well worth it in the tight situation you were in.

I flew an AA5A today for pattern work. That last flap selection to full is a significant increase in drag.

BullHughes
12th Apr 2015, 21:25
Don't underestimate the importance of keeping the aeroplane in balance throughout. A lot of students and low-hour pilots fail to add sufficient rudder with application of full power and this will seriously degrade acceleration and climb performance.