How do you know 'when' an aircraft has stalled?

[ossie]

Consider this scenario I am flying my pitts s1c inverted 20' AGL at 85knots and I feel the stick starting to shake, what should I do?

If this scenario actually occurred you'd have had quite a bit of training and number of waivers under your belt, and you'd be sitting back watching, just watching, this thread, reminiscing what a great flight that was...... :-)))

 

 

[facthunter]

nunans, wing walking on a tigermoth is not a particularly good idea as the drag of the walker makes pitching forward difficult when the power is lost. I think you will find the elevators are in full down position and still not able to lower the nose enough to prevent stalling. I don't think it's done anymore . It does however illustrate that you should know all about what the plane can do, and why it does it.. Took a very sad event to highlight it. There may have been a failure of the rudder control involved too. . The investigation was contentious.. Nev

 

 

[naremman]

Since Tomo opened this thread on Monday we have had posting on physics, aeronautical theory, and many examples gleaned the hard way through experience, and being fortunate enough to share the knowledge.

 

Whilst the numbers of posters has probably not exceeded 40, those who who have followed this thread would be many times more, and what would be the perspective of someone who is the initial stages of attaining RAA Pilot Certification make of the progress of the thread?

 

ALL aircraft are capable of stalling, with varying degrees of severity, and each with their own quirks. High standards of instruction are decidely beneficial to making old pilots. Taking oneself out of the comfort zone with a generous altitude buffer to explore the extremes of an aircraft has no downside. The times when we require superior recovery skill are when height, airspeed and knowledge are not in abundance!!.

 

I have ticked the "like" box for posts from both Facthunter and Turbo throught this thread for their incisive thoughts.

 

Is anyone capable of an effective summary as a consequence of this discussion that provides the one gem that saves a least one neck?

 

 

[djpacro]

On the other hand a lot of people now, and in the future when they come across this thread may well take away advice from any of the posts, good or bad.

You seem to think my posts were bad so they have gone - problem solved.

 

This is a thread which could get someone hurt, so you either need to provide a correct answer, or admit that this was a facetious question. ...... There either IS and answer to this question or the guys should not be left hanging with a thread laced with incorrect data.

A pity that you didn't see the correct answers before I deleted my posts. And, I do NOT need to respond to your directions above.A pity there are so much incorrect data - you had better fix it turbo.

 

thousands of airmen all around the world would have seen it.

Sorry I don't have the time or inclination to follow your fantasy world on FB.

[Wayne T Mathews]

Let's see a show of hands from all those people who have gone out and bought the books referred to since this thread started.

I for one since this thread started Turbz, have downloaded all four of Noel Kruse's free books and have advised six of my friends of the books existence. All six of these friends, like me, used to work for Noel and Phil Asterley back in the late seventies during the Caribou days. Only one of the six has come back to me and said he'd already been told of the books earlier this year, but then, Dave is now a semi retired Sqn Ldr in the reserves. Dave made the comment that Noel is making a lot of sense, and that to this day, when Dave does something close to the edge of the box, he still thinks to himself, "What would Phil say about this?" Given Noel's acknowledgement of Phil's input to the books, it seems reasonable to expect the answer to be in there somewhere.

 

I know you never started this Dave. It is an excellent value discussion though, so please leave your posts up. People are thinking and learning (I hope).

Hear hear...

 

Post edited to repair broken quote formating - Mod.

 

 

[turboplanner]

A pity that you didn't see the correct answers. As for vague references, one was a very specific link to one paragraph in an online text with a suggestion (only a suggestion) that further reading is available in some excellent online books.Free books to download in fact. I didn't say anything about buying books.

You seem to think my posts were bad so they have gone - problem solved.

 

Actually, I did all of this mid-way through the Acrofest so now I have done all that you have asked.

Don't have a problem with what you are saying, or the fact the technically Tomo "started it" on here. However it was started on facebook where thousands of airmen all around the world would have seen it.

 

I accept the books may be free, but my point about a show of hands has produced only one who has obtained the books, and he's one of our most conscientious Instructors.

 

The questions was: "How do you know.......when an aircraft........has stalled?" and, if there was an answer, it should have been posted here, if for nothing else than to correct any misleading posts.

 

I'm proposing to get the books, but human nature tells us many won't, and that's where the risk is, and the question remains unanswered on this forum.

 

 

[Tomo]

Does anyone know what happened to the content of DJ's posts #51 and #53? It was worth reading, seems strange it's disappeared.

 

I'm surprised that some are getting a little frustrated here at not getting an actual answer to the question posed at the title. The question was meant to be a thought provoker, something for you to think about and 'know' in the aircraft you fly. It's a different outcome depending on the type of flying you do, be it S/L cruising stuff, Aero's, Ag flying, etc etc...

 

We should all know the symptoms of an approaching stall in what we fly. Half of the aircraft I fly don't have stall horns, so you go by feel of controls, or whatever, some have stick shakers for the more advanced aero aircraft I believe.

 

Matt Hall had a high speed/High G stall occur to him that nearly ended his career.. How he new he was in a stall and put that stick forward a bit to recover near the water would have taken extreme skill and instinct I reckon.

 

 

[David Isaac]

and the question remains unanswered on this forum.

Not for me it doesn't. You know the wing is stalling (approaching the stall or whatever other description you want) when you go past the 'stall stick' position.

Post edited to repair broken quote formating - Mod.

 

 

[dazza 38]

and the question remains unanswered on this forum.

Not for me it doesn't. You know the wing is stalling (approaching the stall or whatever other description you want) when you go past the 'stall stick' position.

 

Like I mentioned in Post #23.

Post edited to repair broken quote formating - Mod.

 

 

[turboplanner]

and the question remains unanswered on this forum.

Not for me it doesn't. You know the wing is stalling (approaching the stall or whatever other description you want) when you go past the 'stall stick' position.

 

I gave that answer in #2, but who's to say you, Dazza or me are correct for all aircraft attitudes, wing loadings, speeds etc. ???

 

Post edited to repair broken quote formating - Mod.

 

 

[turboplanner]

Just deleted #2 in case

 

 

[ahlocks]

in case of what?

 

 

[turboplanner]

In case my answer is not correct, or, what I believe is partially correct and may lead someone to make a critical mistake.

 

 

[dazza 38]

If pilot has there eyes closed, and a instructor places the aircraft into a Vertical dive, and the a/c has a low airspeed.The student opens their eyes, sees the ground rushing up at them.I dont think they are going to sit there and think sh!t, what did post, #2 or #23 or whatever said to do in this situation.

 

99.9% of pilots are going to open their eyes,windsreen is full of green stuff, panic.Pull back on the stick because the ground is rushing up at them.It is Human nature.The whole key of the excercise which started this thread, was a very accomplished and well respected aerobatics instructor, placed a aircraft into dive, then was waiting for the reaction from a very competent pilot. His first reaction from the sounds of it was to pull back further on the stick (stick already passed stall stick position).No good the aircraft is already stalled hence the low airspeed .He has learnt by this exercise, I have learnt by this exercise, and I am sure that plenty of others have learnt by this exercise. It has made me get off my backside and re- read Aerodynamics books.

 

 

[ahlocks]

...It has made me get off my backside and re- read Aerodynamics books.

Perzactly Dazz!

Although, I did have a dissertation on the diagnosis of lift pixium absentia and how to carry out that diagnosis whilst chanting "oh dear, oh dear" and plummeting earthward underway.

 

 

[turboplanner]

He's been sitting up there for a few days Dazza, perhaps contemplating which of the wing surfaces has stalled.

 

 

[Yenn]

Dazza says. "If pilot has there eyes closed, and a instructor places the aircraft into a Vertical dive, and the a/c has a low airspeed.The student opens their eyes, sees the ground rushing up at them"

 

If the aircraft is in a vertical dive and has low airspeed, would the ground appear to be rushing up? Also would the aircraft be stalled. How does the instructor place the aircraft in a vertical dive at low airspeed? How long would it take for the airspeed to increase? Is the aircraft stalled at that low airspeed?

 

Some people say that stall is all about angle of attack and as far as I can see the angle of attack in a vertical dive would be very close to zero, not 15 or more degrees. Lift would be moving the aircraft horizontally or nearly so, but I don't think the wing would be stalled. In this situation the danger seems to me to be a dynamic stall in the pull to horizontal flight.

 

Don't take my remarks as being a put down or controversial, I just cannot understand some of the remarks made by others.

 

 

[facthunter]

You are right there Yenn. Anytime your trajectory is steep and you are looking over the nose without much height, the likelihood of a stall occurring during the pullout is high. In certain situations like this, NO-ONE could recover the aircraft. Experienced pilots avoid that situation. Phil Unicom didn't recently and hurt himself and bent the plane. Nev

 

 

[David Isaac]

In case my answer is not correct, or, what I believe is partially correct and may lead someone to make a critical mistake.

Hey Tubz, why the lack of confidence in your answer? Were you not taught this? It is one of the first things you are taught in aerobatics, but should be taught to every pilot in basic training.

The answer is the 'stall stick' position because that position does not change for a particular aeroplane in any particular loaded configuration for any flight. This is regardless of the wing loading and attitude. The aeroplane will stall at the same stick position whether straight and level, flaring to land, in a 4 g turn, or in a dive. Pull back past the stall stick position and the wing will start to stall. Un-stall it by pushing the stick forward. You can feel that position where it gets doughy and if the aeroplane is fitted with a stall warning, it will sound each time you go past the 'stall stick' position.

 

For the benefit of some, many aircraft spin with a steep nose down attitude and while they are pointing at the ground and rotating they are only traveling at stall speed (slow) why? Because the wing is stalled and you are in what looks like a rotating dive to the uninitiated to spinning. In this case how do you get out of the apparent dive? Certainly NOT by pulling the stick back, the aircraft is already stalled ... you have to stop the rotation with opposite rudder and break the stall with a brisk forward movement of the stick ... NOT pulling it back. Once un-stalled you then will be in a steep dive and a determined pull up is required to avoid reaching VNE, but don't pull past the 'stall stick' position or you will induce a high speed aerodynamic stall.

 

You can induce an aerodynamic stall in any steep dive by pulling the stick back past the 'stall stick' position. So pull out of the dive by applying enough back pressure to pull out of the dive without overloading the wing and hope you have enough height to recover.

 

 

[ahlocks]

If the aircraft is in a vertical dive and has low airspeed, would the ground appear to be rushing up? Also would the aircraft be stalled.

You can stall a wing at all sorts of speeds if you put your mind to it.

 

Some people say that stall is all about angle of attack and as far as I can see the angle of attack in a vertical dive would be very close to zero, not 15 or more degrees. Lift would be moving the aircraft horizontally or nearly so, but I don't think the wing would be stalled.

Picture an aeroplane with a path perpendicular to the ground but holding say 20 degrees angle of attack while desperately trying to pull out of the dive. There is gravity, thrust and drag present but there is not much lift vector (even if it is horizontal) being generated because it is stalled. Well, there's a bit of horizontal lift being generated off the fuselage for the tail feathers to act against and hold the high angle of attack, but the moral of the story is to recognise that you are stalled, i.e. the aeroplane not doing what it's told and plummeting earthward, break that stall and then you get to worry about pulling out of the dive without stalling again.

 

Don't take my remarks as being a put down or controversial, I just cannot understand some of the remarks made by others.

Me either... I was quite happy to accept the lift pixie theory until all this started.

 

 

[Teckair]

Hey Tubz, you are kidding aren't you? Were you not taught this? It is one of the first things you are taught in aerobatics, but should be taught to every pilot in basic training.The answer is the 'stall stick' position because that position does not change for a particular aeroplane in any particular loaded configuration for any flight. This is regardless of the wing loading and attitude. The aeroplane will stall at the same stick position whether straight and level, flaring to land, in a 4 g turn, or in a dive. Pull back past the stall stick position and the wing will start to stall. Un-stall it by pushing the stick forward. You can feel that position where it gets doughy and if the aeroplane is fitted with a stall warning, it will sound each time you go past the 'stall stick' position.

 

For the benefit of some, many aircraft spin with a steep nose down attitude and while they are pointing at the ground and rotating they are only traveling at stall speed (slow) why? Because the wing is stalled and you are in what looks like a rotating dive to the uninitiated to spinning. In this case how do you get out of the apparent dive? Certainly NOT by pulling the stick back, the aircraft is already stalled ... you have to stop the rotation with opposite rudder and break the stall with a brisk forward movement of the stick ... NOT pulling it back.

 

You can also induce an aerodynamic stall in a steep dive by pulling the stick back past the 'stall stick' position. So pull out of the dive by applying enough back pressure to NOT overload the wing and hope you have enough height to recover.

While stall stick position may apply to aerobatic situations and be in many text books I do not believe it to be as simple as what some people think. If you think about it you will realise an aircraft can be stalled with the stick in any position. In a Thruster aircraft and I imagine a Javelin the stall stick position will change greatly with power setting and nose attitude.

Regards Richard.

 

 

[David Isaac]

While stall stick position may apply to aerobatic situations and be in many text books I do not believe it to be as simple as what some people think. If you think about it you will realise an aircraft can be stalled with the stick in any position. In a Thruster aircraft and I imagine a Javelin the stall stick position will change greatly with power setting and nose attitude.Regards Richard.

No Richard the stall stick position is always the same for a given loaded configuration and therefore flight. I am not talking about stick pressure, it is all about the stick position ... but don't just take my word for it.

The problem is most pilots are scared of the stall and do not practice it, go try it out at a safe altitude, it is great fun and you will find that even in a steep turn the stick is close to the 'stall stick' position, pull past and you will stall in the turn, and that position (surprising to some) will be the same position when stalling in S and L flight.

 

 

[djpacro]

So much incorrect data here, turbo, please get it fixed. We can't let this forum be like a discussion - you must correct each post the instant it appears. Have fun, bye.

 

 

[ahlocks]

Works for me Met!

 

'cept for the aerobatic stuff... bugger that....

 

 

[Teckair]

No Richard the stall stick position is always the same for a given loaded configuration and therefore flight. I am not talking about stick pressure, it is all about the stick position ... but don't just take my word for it.

This theory has puzzled me for some time for the following reason, for example a Thruster will stall with the stick significantly rearward with full power but it takes a lot of forward stick to keep it flying with power off meaning different stall stick positions not stick pressure. I still believe you can stall an aircraft with the stick in any position maybe you can name one you don't think so and I can explain how it can happen.