Take off with stall warning horn

[Pirke]

I recently flew a light sport aircraft off a grass runway.

The regular take off procedure according to POH:
During take-off run smoothly lighten up the nose landing gear until airplane take-off occurs. After take-off accelerate airplane to............... 57 KIAS (106 km/h IAS)

During check out of this type I was told to simply accelerate to 55-60 before doing rotation.

Because of the grass runway I didn't feel comfortable keeping the nose down at those speeds. While flying the C172 I learned to lift the nosewheel while gaining speed on the grass to reduce drag and to save the nosewheel from getting a beating.

So I followed the same procedure, and rotation occurred at around 40 knots indicated, which also happened to be the stall speed (yeah yeah, AoA etc, but let's continue). As soon as the nose left the ground the stall warning horn sounded, and instinctively I put the nose down a bit. It accelerated a bit more, but at around 45-50 knots the aircraft lifted off and immediately the stall warning came on again. I then accelerated in ground effect until the horn stopped.

So while everything went OK, it still didn't feel comfortable. A friend of mine who was flying with me put it all on tape. Looking back at it, the stall warning only sounded for 3-4 seconds, but in my experience it was beeping for 20 seconds... time is relative.

So my question really is: is it normal for stall warnings to go off at take off? What could I have done differently?

nPLJHBWS_nM

[worrab]

The 172 is heavier in its control forces than some - it may be that the aircraft you were flying had lighter controls leading to a bit of over-control.

You can keep the strain off the nosewheel whilst not actually rotating the aircraft. (In a 152 you can lift the nosewheel pretty much at any speed)

If the PoH says not to lift off until 57, then it's not really that surprising that the stall warner sounded when you tried to fly at 40.

[Andrewgr2]

If the stall speed really is 40 kts, then 57 kts seems on the high side for entering the climb.

If the stall speed really is 40 kts and the warner is beeping at as much as 50 kts it probably needs adjusting. Have you checked the stall speed?

If you have taken off and are flying a few inches above the ground gaining speed, then you aren't going to come to much harm if the stall warner beeps.

In aircraft I have flown, I have experienced the odd beep in the very early stages of the climb if the air is turbulent, but I don't think it is normal to experience continuous warnings during the ground run or initial climb.

[IFMU]

I did some real soft field work at X58 in Florida, in a C172. 7000' of grass, very wet with lots of puddles. Water was flinging off the wheels and hitting the wing. I found I could not get it off unless I had the stall horn going. Else, I could never get enough speed to get airborne before the next big puddle sucked the life out of the takeoff roll.

In the same conditions I was able to get the J3 off easily, no special technique and no stall horn. ;)

[Mach Jump]

Seems to me that you used the POH procedure almost exactly for your T/O.

You may have had a more rapid response to your control movements than you expected, due to the very light control forces, and raised the nose a bit suddenly, initially trigering the stall warner.

Also, on many light aircraft, the stall waner is set a little on the sensitive side. This may be why the operators are recommending the non-standard T/O technique.

If this is the case here, they would be better to have it adjusted to the correct setting.

What type of aircraft was it?


MJ:ok:

[Steevo25]

What aircraft were you flying? My aircraft (Jabiru) regularly has the stall warner go off upon rotation. The POH even states that the stall warner may sound. My POH states to lift the nose at 35kts and let the aircraft fly itself off the ground usually between 40 and 45kts. It does have a note saying stall warner may sound. It then goes on to say accelerate in ground effect before climbing at 65kts.

[Chuck Ellsworth]

Who looks at the airspeed indicator at lift off in a light single engine airplane?

[9 lives]

There is no harm flying the aircraft in 1G straight, ball in the middle flight with the stall warning sounding - it's a stall warning. If the plane is actually stalling, it'll probably stop flying soon, so if you're flying, and indeed accelerating, you're fine. Staying in ground effect is wise, if you can.

Think of this entirely differently, a wing would like to lift the aircraft when the AoA is just right, then increase airspeed at that same AoA, and it's going to climb happily. So, as early as possible, lift the nose. As early as you can after that establish that ideal AoA. In a normal C150, you can get to that AoA after about 100 feet of ground roll.

So you're rolling down the runway with the nose held a few degrees up, and the plane is accelerating. Hold that attitude no matter what. It is very likely that you'll get a stall warning - keep the ball in the middle, and hold that attitude. When it's ready, it'll fly. Hold that attitude! You'll find that the stall warning has ended, and the plane is accelerating more into a climb. Likely now, you'll have to lower the nose a bit.

Would you have believed that you could takeoff without "rotating"!?! I think I have just described a Cessna POH soft field takeoff.

Don't worry about hearing a stall warning, if you have the aircraft under control, and you're headed toward somewhere safe, in controlled flight. During "Vref - 5" testing, I have had to fly entire circuits with all speeds flown 5 knots slower than the specified speed for that phase of flight. I heard the stall warning quite a bit - cautious, but no problem - unless the engine quits!!! THEN, you would like bags of speed, unless you're 6" off the runway, with lots ahead of you.

[john_tullamarine]

Sport aircraft are not my forte but I suspect that PEC work is not to the standard of certificated Types. All sorts of funny things happen around the stall to ASIs - errors can get significant.

[Pirke]

Thanks for all the replies. If it wasn't for the stall horn I would also say I did it by the book. I'm just not used to hearing that horn on take off. Usually it only comes on when I start the flare. We were well within M&B limits and the aircraft was an Evektor SportStar RTC. It flew fine and wanted to accelerate and climb, so from a performance point of view everything was as usual.

It could indeed be as simple as the horn being a bit sensitive, or the ASI might be misreading. The POH doesn't mention stall horn can happen on take off, but if that's common for this aircraft than that could also be why the instructor said to accelerate to 55-60 before bringing the nose up.

On my next flight in this aircraft I will do some slow flying and stalls, just to see how much margin there is once the horn starts beeping. During the checkout we did some stalls, but I simply didn't pay attention to the speeds as my focus was keeping the aircraft steady and looking outside.

[tecman]

Pirke, I think your T/O is generally fine for the conditions of the field and the day. In an LSA the operating speeds are of course quite low, and the acceleration is brisk. The other thing is that the nosewheels are typically quite fragile - some would say particularly so in the SportStar.

The stall warning horn/vane is easily checked at altitude. In my P2202JF VLA, it's set very conservatively indeed. I suppose I could tweak it but I've never bothered. (The LSA version doesn't even have one, so I don't feel especially threatened).

Many GA pilots do require a bit of re-training with the LSAs in terms of getting the weight off the nosewheel and never holding the wheel on the runway, even a little bit. As someone previously said, you can take the weight without resorting to that. In gusty conditions, at low speeds, you do need to make sure that you have sufficient directional authority, either via the nosewheel or the rudder. These are very light aircraft and, although experience leads to very good capabilities, a bit of prudence in the early stages is not a bad thing. The saving grace is that the acceleration is very brisk indeed, so by firewalling the Rotax throttle in line with normal practice, you minimize the time you are vulnerable. Nothing at all different in principle to any light aircraft, just a slightly different set of emphases.

Happy flying!

[Flyingmac]

Slap a bit of sticky tape over the vane if it bothers you.:ok:.

The Eurostar/Sportstar accelerates so quickly, I'm surprised you have time to monitor the ASI.

[9 lives]

why the instructor said to accelerate to 55-60 before bringing the nose up.

Herein may lie a part of the challenge you face. This type of instruction would be appropriate for a Piper Navajo, or a DA-42, but is probably not for your lighter type.

Though I have not flown the type you mention, I imagine, that like other light aircraft, it responds to be being "flown" even before reaching flying speed. Therefore, you should fly it. If you would think to correctly position ailerons and elevator while taxing in a cross or tailwind, then when flying that type you would also want to apply flight controls at the beginning of the takeoff roll, which would have the effect to promote flying.

If the elevator effectiveness is adequate to lighten the nosewheel, the rudder will be effective enough to steer with the nosewheel having little effect.

[tecman]

ST, you're right about correct control positioning etc. But in my experience there are LSAs around without particularly good rudder authority. It is possible to get airborne and then be disappointed in the ability to check the weathercock effect in a strong wind. This can be compounded by the powerful slipstream effects in these generously powered little machines, typically making e.g. a take-off with a strong left crosswind that much more challenging.

Remember that many LSA types exist outside the certification system, so approaching with an open mind is prudent. There are of course several types, such as some Tecnams, which have parallel lives in the LSA and certified worlds.

[FleurDeLys]

I would be interested to climb to a safe altitude and check the IAS (in all configurations) at stall warning and actual stall against the book. The stall warning tab is a crude mechanical device and, as such, easily damaged. But barring such damage, it's not likely to give consistent false indications. If, however, the stall warning sounded the requisite interval above the actual stall, but both were occurring at different IAS to those in the book, it could indicate damage/obstruction/calibration issues in the PITOT system/ASI?

[rusty sparrow]

@IMFU

"In the same conditions I was able to get the J3 off easily, no special technique and no stall horn"

Yep - fly by feel. I'm just learning the delights of the L4 Cub :)

[Jan Olieslagers]

During check out of this type I was told to simply accelerate to 55-60 before doing rotation.That's utter rubbish. You simply don't "do rotation" on a (very) light plane. Your POH is much more correct with its until airplane take-off occursThe plane decides when it leaves the ground, not the pilot. The pilot's job is to be pro-active on crosswind and other forms of turbulence, and remaining on axis, before AND after take-off. And, once airborne, lower the nose and build up airspeed, as perfectly described.

[Mariner9]

Totally agree Jan.

I've around 700 hours on LSA's, and holding the nose up till the aircraft takes flight is the technique I have successfully used for at least 699 of those hours!

[India Four Two]

Slap a bit of sticky tape over the vane if it bothers you.

All the glider tow-planes I've flown in recent years always have a blown stall-warning fuse. Funny that! ;)

[IFMU]

The Pawnees I have towed with generally had the breaker for the stall warning light pulled. Otherwise it is a distraction. It is fun, though, to split-S after release and pull a couple G's all the way through with it in. Lights up and if you keep it lit all the way you are only doing 120 out the bottom.

The super cub, like its little brother, was unencumbered by any such nonsense.

[Big Pistons Forever]

The Pawnees I have towed with generally had the breaker for the stall warning light pulled. Otherwise it is a distraction. It is fun, though, to split-S after release and pull a couple G's all the way through with it in. Lights up and if you keep it lit all the way you are only doing 120 out the bottom.

The super cub, like its little brother, was unencumbered by any such nonsense.

My gliding club has a Pawnee and anybody who did a Split S in it would be fired on the spot................

[piperboy84]

BPF My gliding club has a Pawnee and anybody who did a Split S in it would be fired on the spot................

Pretty black and white, no grey area there huh !!!!

[9 lives]

It is fun, though, to split-S after release and pull a couple G's all the way through with it in.

Hmmm, I wonder how many G's? G meter equipped aircraft?

[Capt Kremmen]

Whats a 'stall warner' ?

[Shaggy Sheep Driver]

Are students really being taught to 'rotate' at a certain speed in a SEP? As has been said, that's entirely innappropriate in such an aeroplane - very poor technique.

I'm just learning the delights of the L4 Cub

Lovely fun aeroplane! I have fond memories of one of those I flew for a few years.

The stall warner in the Chippy is pre-stall buffet. For a soft field take off you can drag a Chippy into the air way on the back of the drag curve and accelerate in ground effect while 'feeling' the wing coming alive as the AoA is gradually reduced until the wing is in the positive side of the drag curve and a normal climb-away can be made. The ASI plays no part whatever in this.

[9 lives]

Whats a 'stall warner' ?

A change in the sensations of the wing's ability to produce the required lift at high angles of attack. May include buffet, slight wing drop, changed control forces, and in some aircraft types, an annoying little horn. ;)

[mad_jock]

this is what happens taken from another thread

?????????????? ??? ?????????? ?????? ?? ?????? ?????????????????. ???????? 05.11.2014 ?. - YouTube

[Piper.Classique]

As step turn and SSD say.....
I would just add that the feel of any aircraft is enhanced by holding the stick (or that funny steering wheel thingy) LIGHTLY and removing boxing gloves before flight
:)

[Pirke]

@mad_jock: I don't know what thread it came from, but if the person on the right is the instructor, he should know that when you apply full throttle the nose goes to the left. Nobody corrected for that. And the student (I think) on the left should never have been allowed to pull up the nose like that while flying towards the tree tops, that's an accident waiting to happen.

@SSD: During my lessons in a C172 I was taught to gain speed, then lift the nosewheel a bit, and it will fly off on its own. On a grass runway you lift the nose sooner to reduce drag and wear. Once enough speed is gained, it will fly without additional input. Some might call that part where the nose is lifted rotation.

[edit]

I now see the other thread. Let's keep those discussions there.

[Shaggy Sheep Driver]

Pirke, please read my post 25 again to see what I really said.

[Mach Jump]

Pirke: What aircraft type were you using?


MJ:ok:

[Pirke]

Evektor Sportstar RTC

[Mach Jump]

Hmmmm.

By coincidence, a close relative of the Harmony in the accident clip.


MJ:ok:

[Jan Olieslagers]

Whats a 'stall warner' ?

Typical PPL'ers fetish toy.

[150 Driver]

In answer to the question above, for odd reasons, I did my PPL training (2011-12) in two different flight schools.

One was a commercial airport in East Anglia, flew C172's off a long concrete runway and had a number of youngish instructors. Most definitely they drummed into students about 'rotation speed', even the learned by rote safety briefing to be given prior to pulling on to the runway had to refer to 'At x knots we will rotate'.

The grass strip that I had started at and at which I finished my PPL (in a C150/152) had a 'more mature' instructor whose instruction was get the front wheel off the ground asap, then let the plane fly itself off when ready, using ground effect as an ally.

I guess both have their place in the right situations.

[India Four Two]

My gliding club has a Pawnee and anybody who did a Split S in it would be fired on the spot................

BPF,
I agree. A student and I in a Blanik were nearly killed by a tow-pilot doing that when he thought the rope had released. We ended up accelerating nearly vertically downwards. Using two-hands, I managed to release going through about 100 kts, whereupon the Blanik did a stick-free 3G pullup, attempting to regain the trimmed speed of 50 kts!

I used up the fourth of my nine-lives on that occasion. Luckily, no more since.

[john_tullamarine]

Oz tugs have mirrors .. .which the pilot watches closely to actually SEE the line drop away before doing things which would cause such frights.

Then again, that didn't always work in reverse .. had a Blanik (not quite) release (and not check the rope visually) ... a booming day .. and suddenly found myself inverted into a spin at around 500ft in the SuperCub. Both I and the glider instructor released much at the same time and the rope was lost although I confess to not having much concern about that at the time.

Almost damaged the tree leaves and branches during the recovery .. some constructive debriefing with the trainee pilot after he landed ...

[Piper.Classique]

Um. Don't all tugs have mirrors? They certainly do in UK and France.
They don't all have mechanical stall warnings, that's for sure. Those that do have such things usually have them correctly calibrated, unlike many of the trainers in club use. I flew a DR400 the other day which kept beeping away at 70kts. Grrr.

[India Four Two]

PC,
Almost all the towplanes in Canada that I have flown have mirrors, but I think the one in my incident did not.

The clubs in Alberta adopted an SOP many years ago, which was much safer but was introduced mainly to reduce cylinder head cracking. A gentle left-turn, selection of full-flap and a slight power-reduction. After one minute, a further power reduction and a full-flap descent at 80 mph.

[Shaggy Sheep Driver]

I guess both have their place in the right situations.

No, they don't. The first scenario you describe (rotate speed) is not correct for that class of aeroplane. The second technique (take the weight off the nosewheel and it'l fly when ready) is correct.

We used to watch in horror visiting PPLs at Barton who had been trained (not at Barton) who would hammer down our bumpy 27, no attempt to relieve the poor old nose wheel which is not designed to take that sort of punishment, then at the magic speed, rotate. Those were aeroplane drivers, not aviators. Didn't they feel it was pi55 poor aeroplane-wrecking technique?

[9 lives]

["Rotating" a tricycle, conventional tail GA aircraft]

I guess both have their place in the right situations.

Yes, the right situation for accelerating, and then "rotating" an aircraft is when it is a T tailed Piper, or something approaching an airliner.

Otherwise, there is no right situation for driving the nosewheel down the runway on takeoff, get it light/off ASAP every takeoff. If you're afraid to lighten the nosewheel (perhaps directional control in a crosswind), then you should not be opening the throttle on that runway then.......

[Sop_Monkey]

Training for an earlier career, part of it included the ASI "covered" and no stall warning. In fact all except the RPM and manifold pressure were "covered". If you get used to an aircraft it will let you know when its not happy. You can tell a lot flying by "feel". On a lot of light SE A/C, not all, the aerodynamic warning of an impending stall, especially a "high speed stall" is very pronounced, albeit with less of an air speed margin.

All this should be practiced at stalling heights of course, not low level.

[150 Driver]

SSD, As an inexperienced PPL who had been taught two different ways - to rotate or not to rotate - I initially put it down to runway type (grass versus tarmac). At the time I had too much to think about to 'feel' much at all.

However, soon after purchasing my SEP the nosegear was found to have cracks in it and needed changing. At that point I realised that anything other than protecting an expensive part was pi$$ poor technique. From then its been yoke back and fly away.

Right answer arrived at for possibly the wrong reason !

[9 lives]

Right answer arrived at for possibly the wrong reason !

Exactly! Whenever you are receiving training or mentoring, ask yourself: Is that person directly involved with, or paying for, the maintenance on that aircraft. If not, take it with a grain of salt. If you're training with an instructor who owns their own aircraft, that's a darn good start.

Otherwise, where is the incentive for an instructor to train beyond only the minimums (even if they have the skills)? Certainly, if an instructor trains what I advance as the better way, for plane, pilot and safety, the instructor sees that training as "going beyond" and increasing liability if something happens later.

But instead, if a pilot is well trained, with the variation of possibilities properly presented, that pilot will fly with more skill, and a wider range of "normal" will be in their comfort zone. This would include stall horn during climbout.

For me, flying with the stall horn chirping, in and of itself does not bother me, if I have planned that condition of flight, and am in the right part of the sky. What [I]does bother me with flying the stall horn is that at less than 500' AGL an engine failure will be irrecoverable, and your options are otherwise very restricted.

[Shaggy Sheep Driver]

150 - quite so!

I'm pleased you discovered the noseleg cracks before it gave way (which it can do when a considerate pilot fully holds off his landing, if a cowboy has done the damage already). If it gives way, I'm sure you know the sort of bill you'd get to put everything right.

The AAIB reports in UK every month are full of noseleg failures on landing. Very expensive (prop, firewall, shock loaded engine), and puts everyone's insurance premiums up. And quite avoidable when the correct technique is used on T/O and on landing.

[Caboclo]

Going all the way back to the OP:

What could I have done differently?


You ould have done a lot of things differently, like forcing it to stay on the ground till well above stall speed. But that's really not necessary. What you did is fine, especially for a grass runway. Listen to the plane, let it lift off whenever it wants to, then keep it in ground effect till it's ready to climb. Don't worry about the stall horn. Of course, that all depends on having the trim properly set; that's why it's on the checklist.

[9 lives]

like forcing it to stay on the ground till well above stall speed

A worrisome concept. I make it a priority to never force an airplane to do anything.

I very much more:

Listen to the plane, let it lift off whenever it wants to

..... with some light nose help