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

[djpacro]

Some interesting notes were here ...

 

 

[Guernsey]

Good one DJP.

 

 

[facthunter]

Yeah, I'm into physics and aerodynamics myself, but some might find a lot of this a bit heavy going when you get in to lift coefficients for instance, in treatment of stalling. You can discuss these things in simpler language and often that is a big part of the task, when getting it across to pilots.

 

Most pilots are s**t scared of a stall, but most stalls are "caused" by pilot input. The aeroplane won't stall itself even if the prop stops

 

The question was how do YOU KNOW when an aeroplane has (is) stalled? Graphs etc are not the solution to that question that most would seek although they do explain what a stall is, and most people wouldn't really know, but that's a different question. Nev

 

 

[turboplanner]

The question was how do YOU KNOW when an aeroplane has (is) stalled?

DJP, you started this, and you can see from the huge variation of knowledge above that a lot of people have very little understanding of the principles let alone knowing when the aircraft is stalled.

 

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. Vague references to text books it not enough. There either IS and answer to this question or the guys should not be left hanging with a thread laced with incorrect data.

 

 

[fly_tornado]

I thought the purpose of this thread was to not find an answer and berate people with a limited understanding, ie see how smart I am and how stupid you are?

 

 

[dazza 38]

DJP, you started this, and you can see from the huge variation of knowledge above that a lot of people have very little understanding of the principles let alone knowing when the aircraft is stalled.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. Vague references to text books it not enough. There either IS and answer to this question or the guys should not be left hanging with a thread laced with incorrect data.

Djp is at Acrofest today.

 

 

[turboplanner]

The minute Acrofest is over would be a good time.

 

 

[facthunter]

I'm not into picking on anyone (just to set the record straight if needs be). We all approach these things from a different aspect. I've heard most of these discussions for over 50 years now, same old arguments. What we need is clarity and understanding, in the basics.

 

Often in aviation, (where it is least desireable), you get exams where the correct answer is actually wrong, but the pet theory at the time is getting a run, so that had better be the answer you give, or you will be marked wrong.

 

We get obsessed with numbers and formulea. things like VMC(a) VFTO Vle etc etc, Acronyms by the truckload and many memory items that just aren't necessary if you approach the whole sublect of flying from a logical management of the operation as a sequence of actions that are NOT invariable but will change depending on the circumstances that present on the day. You have awareness of the total situation as the start aim point of your operation.. This can't happen on day one in your training, but you shouldn't continue with the "learn this, and all will be well", process, either. Nev

 

 

[David Isaac]

I thought the purpose of this thread was to not find an answer and berate people with a limited understanding, ie see how smart I am and how stupid you are?

Hi FT, I hope that the purpose of any question on this or other forums is not intended to divulge who is smarter than who, but rather evoke some input from many without the fear of being berated, such that the majority of us can learn.

The question is actually quite clever and has clearly invoked a lot of consideration by many. The question is really quite simple and does not ask for any theory on lift or aerodynamics but simply how do you KNOW when the aircraft has stalled? You are flying along in a range of normal flying activities and the aerofoil stalls ... how do you KNOW it has stalled ... what is the aircraft doing, what are you doing, what sensations if any. Not all aircraft have a stall onset buffet, not all aircraft have a stall warning horn ... how do you KNOW it has stalled or stall is imminent?

 

The stall stick position has to be a good simple starting point for consideration.

 

 

[fly_tornado]

It's not really that clever, you are getting people arguing between a partial stall and a full stall.

 

 

[facthunter]

Can you elaborate on that FT? Nev

 

 

[Guest nunans]

I'm interested in this thread as my aircraft (which i've yet to fly) will be the first plane i've flown that doesn't have any stall indicator or audible alarm fitted. Add to that the info i have from another owner who tells me there is NO buffet or warning signs prior to the stall, it just drops a wing and falls.

 

To me unless you want to fly aerobatics then stalling is undesirable and instead of "How do you know when the aeroplane has stalled?" it should be "what can be done to avoid stalling the aircraft?"

 

So Does this sound right? To avoid stalling the aircraft keep all turns as shallow as reasonably possible, especially climbing turns. Try to fly in good conditions where sheer, gusts and turbulance are minimal. And most of all, avoid pulling back alot on the controls (or avoid pushing forward too far if inverted but that's aeros) In the end it's for/aft stick position that counts.

 

 

[kaz3g]

The question is actually quite clever and has clearly invoked a lot of consideration by many. The question is really quite simple and does not ask for any theory on lift or aerodynamics but simply how to you KNOW when the aircraft has stalled? You are flying along in a range of normal flying activities and the aerofoil stalls ... how do you KNOW it has stalled ... what is the aircraft doing, what are you doing, what sensations if any. Not all aircraft have a stall onset buffet, not all aircraft have a stall warning horn ... how do you KNOW it has stalled? The stall stick position has to be a good simple starting point for consideration.

Perhaps at that moment in time when it happens unexpectedly the clearest indication is that things no longer work the way the pilot expects them too... pulling the elevators up doesn't raise the nose, opposite ailerons don't stop the roll.

 

Yes, I know that you can be pushing too hard over the top and stall, and I know that some aircraft respond well to aileron inputs even when stalled, but for most of us turning downwind on take-off or even onto base on landing are the most dangerous moments; low altitude, reduced speed and an angle of bank are the set up if concentration/awareness lapses.

 

But that big kero burner descending through 30,000 with the nose up and no power sticks in my mind.

 

kaz

 

 

[facthunter]

Have a thorough training in it, in a plane that can really legally stall, with an instructor who is not afraid of stalls. There's no other way to do it. I feel really sorry for those pilots who have not done it and they are short-changed. It was a mistake to remove it from the syllabus. You MAY get away with it flying Cessna 172's etc as they are as near to fool-proof as you can get, but fool's use such ingenuity to get around good design. (Like loading the plane tail heavy). etc

 

The trouble is that if the plane stalls, the nose usually drops or the aircraft rolls and the nose drops, so what does the average pilot do? Instinctively pulls the stick right back, because they are looking at the ground. It's a natural thing to do, ( like picking up a dropped wing with aileron) and especially disasterous if the rudder is not centred..( ball in centre). Nev

 

 

[fly_tornado]

Can you elaborate on that FT? Nev

you are over thinking things.

 

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?

 

 

[turboplanner]

The Cessna is another aircraft far more docile than a Jab, but look at the number of people who have been killed just mustering.

 

It's the unusual attitudes which will catch you out, like concentrating on several things at once on a turn, photography, unexpected gusting etc.

 

 

[turboplanner]

This shows why you need to know what is happening and react with the subconscious and not try to remember a brain full of theories.

 

Follow the flight and count how much time there is to react after the turn tightens.

 

 

 

[Guest nunans]

you are over thinking things.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?

Go full power... if you're flying level and you have power on then the stick won't start to shake?

 

 

[djpacro]

DJP, you started this.

nope I didn't.Anyway, I will delete my posts and leave you to it, bye.

 

 

[Guest nunans]

This shows why you need to know what is happening and react with the subconscious and not try to remember a brain full of theories.Follow the flight and count how much time there is to react after the turn tightens.

 

That was terrible, and with a commercial pilot at the controls, 1200hr and 570hr on type... what hope is there for a low hour rec pilot?

 

 

[David Isaac]

It's not really that clever, you are getting people arguing between a partial stall and a full stall.

The question was how do you know .. and whether the stall is partial or full the answer is still valid.I don't see it as arguing FT, but it is interesting and valuable discussion because it has everyone thinking about it.

 

 

[David Isaac]

nope I didn't.Anyway, I will delete my posts and leave you to it, bye.

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).

 

 

[David Isaac]

DJP, you started this, and you can see from the huge variation of knowledge above that a lot of people have very little understanding of the principles let alone knowing when the aircraft is stalled.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. Vague references to text books it not enough. There either IS and answer to this question or the guys should not be left hanging with a thread laced with incorrect data.

Tubz,

I don't see it that way at all.

 

Firstly DJP did not start this he has been quoted as asking his aerobatic students this question in the past and there is nothing facetious about the question at all, it is a perfectly valid question and the text book references answer the question. If we are not prepared to do some self study to learn basic principles of flying, what the hell are we doing flying?????

 

The thread is hardly in any form dangerous, it has provoked some serious thinking and can only be good value in the end. If someone doesn't understand what is happening at stall and stall onset, then ask here or better still go ask your instructor for some stall training or go up to 3K and do some practice (as Nev suggests in his above post #129). That is why incipient spinning should still be taught, (because it is legal in RAA but spinning is not) ... but I am on my soap box again and I apologise.

 

 

[kaz3g]

... incipient spinning should still be taught, (because it is legal in RAA but spinning is not) ... but I am on my soap box again and I apologise.

Don't apologise, David. I absolutely agree and I'd say everyone should have to learn to recover from a developed spin in a suitable aircraft before they are turned loose on the world. It's standard fare for gliding and it was for GA once upon a time, too.

 

kaz

 

 

[turboplanner]

If we are not prepared to do some self study to learn basic principles of flying, what the hell are we doing flying?????

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.

 

Human nature being what it is I'd suggest that the answer might be close to zero. 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.

 

Where does that leave them?