Stall stick position
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FU2
Can't disagree with that. I think the way to look at this is that what the Weasil was told was an aide to training that was helpful in a given situation, rather than gospel. I remember using lots of 'instructors porkies' myself in the past to keep the students brain free of technocrap at important moments.
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Can't disagree with that. I think the way to look at this is that what the Weasil was told was an aide to training that was helpful in a given situation, rather than gospel. I remember using lots of 'instructors porkies' myself in the past to keep the students brain free of technocrap at important moments.
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Folks,
In a previous life free of significant CofG, configuration and propwash impositions, the stick position was an aid to identifying a pitch rate that was at the stall boundary and, once prestall buffet was identified, a stick position that meant that all further manoeuvring for max performance could only entail lateral control movements. If it happened that your life (in the particular environment) depended on manoeuvring at Cl(max) then it was a useful teaching point.
It demonstrated that, in a fixed configuration, changes in airspeed were irrelevant to maintaining Cl(max) as the horizontal stabiliser/elevator encountered the same relative airflow as the wing - once established, all the niceties of wing downwash etc were self-compensating!
Why was it useful?
Nobody got out a ruler - the message simply was:
Stop pulling!
In all things aviation, there are two major crimes:
+ "chopping wood with a scalpel", and
+ "conducting brain surgery with an axe".
Our primary responsibility (after identifying that the above techniques are mutually exclusive) is to apply the correct approach to the circumstances.
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Stay Alive,
[email protected]
In a previous life free of significant CofG, configuration and propwash impositions, the stick position was an aid to identifying a pitch rate that was at the stall boundary and, once prestall buffet was identified, a stick position that meant that all further manoeuvring for max performance could only entail lateral control movements. If it happened that your life (in the particular environment) depended on manoeuvring at Cl(max) then it was a useful teaching point.
It demonstrated that, in a fixed configuration, changes in airspeed were irrelevant to maintaining Cl(max) as the horizontal stabiliser/elevator encountered the same relative airflow as the wing - once established, all the niceties of wing downwash etc were self-compensating!
Why was it useful?
Nobody got out a ruler - the message simply was:
Stop pulling!
In all things aviation, there are two major crimes:
+ "chopping wood with a scalpel", and
+ "conducting brain surgery with an axe".
Our primary responsibility (after identifying that the above techniques are mutually exclusive) is to apply the correct approach to the circumstances.
------------------
Stay Alive,
[email protected]
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I think also that anybody using such approximations to explain something should make it clear that it is a useful model or explanation, not the gospel truth.
Most scientific or explanations do contain a lot of approximations and innacuracies - but are good enough. The problem comes when somebody does not understand that it is an approximation, and thus can't necessarily be applied to other circumstances.
G
Most scientific or explanations do contain a lot of approximations and innacuracies - but are good enough. The problem comes when somebody does not understand that it is an approximation, and thus can't necessarily be applied to other circumstances.
G
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Well I have been following this thread with great interest. I appreciate all the comments folks as it has opened my eyes up a little.
Especially the comments regarding stick pressures as opposed to positions etc. There is obviously still so much more to learn in flying for me and I can't wait. I'm going to the USA inabout 3 weeks to complete my commercial and a degree. I seriously hope to do some aerobatic flying whilst there also.
Happy New Year's All.
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"..You must ensure you don't cross his nose, give him a shot at you. That is critical!" Malan
Especially the comments regarding stick pressures as opposed to positions etc. There is obviously still so much more to learn in flying for me and I can't wait. I'm going to the USA inabout 3 weeks to complete my commercial and a degree. I seriously hope to do some aerobatic flying whilst there also.
Happy New Year's All.
------------------
"..You must ensure you don't cross his nose, give him a shot at you. That is critical!" Malan
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Here's one from the archives! It looked interesting when I saw the "useful links page" so I replied to it. Didn't realise how old it was. 
I have been using the 'stick position' idea for the last couple of days to teach budding new instructors how far to check forward in a spin recovery. There are a few who are much more scared of spinning than the others, so in order to keep their mind at ease I demonstrate that if we do a max rate turn or slow flight, there is a postion on the control column at which the stall warning will come on, and if you pull a wee bit further the a/c will stall.
"That position is as far as you need to check forward to unstall" I tell them, and then they know what to do, and feel confident enough to have a go.
I thought up until now that it was the gospel - I got it from the late Tom Middleton and he was clever so it was right, until I've started reading this thread and now I'm not sure again.
But I won't be putting any doubt in their head until they pass! As long as they don't dig themselves into having to explain it in the briefing room or in the a/c, they can do it if they like. Expediency.
Sidebar - Genghis, what do you mean by 'reversible controls'?
I have been using the 'stick position' idea for the last couple of days to teach budding new instructors how far to check forward in a spin recovery. There are a few who are much more scared of spinning than the others, so in order to keep their mind at ease I demonstrate that if we do a max rate turn or slow flight, there is a postion on the control column at which the stall warning will come on, and if you pull a wee bit further the a/c will stall.
"That position is as far as you need to check forward to unstall" I tell them, and then they know what to do, and feel confident enough to have a go.
I thought up until now that it was the gospel - I got it from the late Tom Middleton and he was clever so it was right, until I've started reading this thread and now I'm not sure again.
But I won't be putting any doubt in their head until they pass! As long as they don't dig themselves into having to explain it in the briefing room or in the a/c, they can do it if they like. Expediency.
Sidebar - Genghis, what do you mean by 'reversible controls'?
Do a Hover - it avoids G
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Chicken
It is rude to reply to other people’s mail, but reversible controls are ones you can move normally during the walk around. Irreversible controls are those that are fully power operated, which appear locked solid during walk around.
For what you are discussing (spin recovery technique) reversible controls allow any aerodynamic loads on them to be felt at the pole. Indeed, as I am sure you brief your students, it may be necessary to apply considerable force in the cockpit to stabilise (reversible) controls that want to blow about which way. To a pilot used to flying only with respect to forces, having the stick or rudder thrashing about of its own accord can be quite off putting. This is when it is useful to encourage them to look down at the controls and physically put them in to whatever position is appropriate until more normal circumstances prevail.
While I think it is open to some doubt whether the precise position you are briefing them to move the stick to is absolutely correct in all circumstances, the notion of getting them to look at the stick and moving it by numbers in spin recovery is very important. Make them use two hands too!
I was always taught to apply opposite rudder (and really force same against the stop), then after a pause (of about half to one turn – which is just long enough to shout out loud PAUSE) PLACE the stick in the centre position (controls neutral when on the ground) and from there on move it progressively forward (not by feel but by position) until recovery starts (this does mean that if recovery does not start you will eventually be holding fully forward stick). As soon as recovery does start, really force the controls to central (especially the rudder, about which there must be little delay) and then execute a normal dive recovery.
This has worked for me since 1955 and since I have just about quit now all looks set fair for a 100% record.
Cheers
It is rude to reply to other people’s mail, but reversible controls are ones you can move normally during the walk around. Irreversible controls are those that are fully power operated, which appear locked solid during walk around.
For what you are discussing (spin recovery technique) reversible controls allow any aerodynamic loads on them to be felt at the pole. Indeed, as I am sure you brief your students, it may be necessary to apply considerable force in the cockpit to stabilise (reversible) controls that want to blow about which way. To a pilot used to flying only with respect to forces, having the stick or rudder thrashing about of its own accord can be quite off putting. This is when it is useful to encourage them to look down at the controls and physically put them in to whatever position is appropriate until more normal circumstances prevail.
While I think it is open to some doubt whether the precise position you are briefing them to move the stick to is absolutely correct in all circumstances, the notion of getting them to look at the stick and moving it by numbers in spin recovery is very important. Make them use two hands too!
I was always taught to apply opposite rudder (and really force same against the stop), then after a pause (of about half to one turn – which is just long enough to shout out loud PAUSE) PLACE the stick in the centre position (controls neutral when on the ground) and from there on move it progressively forward (not by feel but by position) until recovery starts (this does mean that if recovery does not start you will eventually be holding fully forward stick). As soon as recovery does start, really force the controls to central (especially the rudder, about which there must be little delay) and then execute a normal dive recovery.
This has worked for me since 1955 and since I have just about quit now all looks set fair for a 100% record.
Cheers
For one example of stalling and unstalling at the same stick position, I was demonstrating a spin in a Blanik glider. Shortly after entering the spin and still holding full back stick before doing the recovery procedure, the airspeed began increasing rapidly and we quickly decided an expedited spiral dive recovery better fit the situation -- low VNE and Rapid downhill acceleration.
Because of our light weight, the Blanik was close to forward CG limits. Heavier people may find different behavior.
Because of our light weight, the Blanik was close to forward CG limits. Heavier people may find different behavior.
I agree about 90% with JF, my disagreement being that the level of identification of the spin mode (particularly direction) that John has, and so-far I've always managed to demonstrate, may not be shared by every PPL - particularly given the modern refusal to teach spinning.
For that reason, when certifying a new non-aerobatic type (which I do a couple of times a year) I always look first for a controls centralised recovery. If I get a 100% success rate from that (pretty much guaranteed in anything with cruciform tail for example), I'll always aim to publish that as the recommended recovery for that type, for the following reasons:-
(1) It doesn't require enough ability to identify which way the aircraft is spinning.
(2) It can be performed in the incipient spin, whereas the convention that John has described requires the spin to be developed enough to identify the spin direction.
Expanding on (2) slightly, the RAF has always taught a "loss of control" drill preceding the spin recovery drill - that loss of control drill is what I always hope will be an acceptable spin recovery. Civil GA teaching is to perform a full spin recovery once the spin mode is identifiable. In my opinion this leads to unnecessary loss of height when recovering from an inadvertent spin.
G
Note 1: For the benefit of instructors, on most light aircraft all the primary controls are reversible, but trimmers are generally irreversible - that is you can waggle it out on the airframe all you like and nothing happens in the cockpit.
Note 2: By co-incidence, I've just read this whilst taking a break from writing a section on stalling and spinning of small aeroplanes in what I hope will eventually become my PhD thesis. I believe that in the trade, this is known as "Doing a Darrol".
For that reason, when certifying a new non-aerobatic type (which I do a couple of times a year) I always look first for a controls centralised recovery. If I get a 100% success rate from that (pretty much guaranteed in anything with cruciform tail for example), I'll always aim to publish that as the recommended recovery for that type, for the following reasons:-
(1) It doesn't require enough ability to identify which way the aircraft is spinning.
(2) It can be performed in the incipient spin, whereas the convention that John has described requires the spin to be developed enough to identify the spin direction.
Expanding on (2) slightly, the RAF has always taught a "loss of control" drill preceding the spin recovery drill - that loss of control drill is what I always hope will be an acceptable spin recovery. Civil GA teaching is to perform a full spin recovery once the spin mode is identifiable. In my opinion this leads to unnecessary loss of height when recovering from an inadvertent spin.
G
Note 1: For the benefit of instructors, on most light aircraft all the primary controls are reversible, but trimmers are generally irreversible - that is you can waggle it out on the airframe all you like and nothing happens in the cockpit.
Note 2: By co-incidence, I've just read this whilst taking a break from writing a section on stalling and spinning of small aeroplanes in what I hope will eventually become my PhD thesis. I believe that in the trade, this is known as "Doing a Darrol".
Do a Hover - it avoids G
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Sorry Genghis, but I do not see how comments about the merits of the centralisation technique (as a reaction to an inadvertent loss of control for inexperienced pilots flying non-aerobatic aeroplanes) has got much to do with Chickens question about teaching spin recovery to would be instructors!
Cheers
Cheers
I hope that anybody being taught a spin recovery, whether a baby pilot or baby QFI will be being shown the POH recovery for the type being flown, even if that differs from the SSR. If there are other recoveries used on other types, I'd suggest that's a subject for ground-discussion or when flying that other type.
However, my point was not about training QFIs, it was primarily about the best spin recovery not being universal, and that what is given for any particular aeroplane should be the best available for that aeroplane.
My secondary point is that I disagree with the teaching only of a spin recovery drill which can only be executed (in the case of an inadvertent spin) once the incipient phase is sufficiently progressed that the spin direction is known - by which 250-500 ft height loss is likely in the most benign light aircraft.
G
However, my point was not about training QFIs, it was primarily about the best spin recovery not being universal, and that what is given for any particular aeroplane should be the best available for that aeroplane.
My secondary point is that I disagree with the teaching only of a spin recovery drill which can only be executed (in the case of an inadvertent spin) once the incipient phase is sufficiently progressed that the spin direction is known - by which 250-500 ft height loss is likely in the most benign light aircraft.
G
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Thanks Genghis and John
Always good to get some things reinforced and learn some new stuff! I have made sure they know Rudder PAUSE check forward in that order is the start of recovery, but min. height loss dictates a rather rapid dive recovery without a secondary stall.
The bit about horses for courses and read the POH is also there, although I haven't spun many (C152, PA38 and DH82a) different recoveries.
Genghis - I have told them the difference between what we're doing here (in their spin recovery training for an instructor rating) and what they'll actually do in the a/c with Mr Uncoordinated is when it's the real thing they'll realise how little height they've got, and those magic three words will come back to them...
"I HAVE CONTROL"
Although if I can talk our committee into getting an aerobatic aeroplane over summer it will be much more fun (for me at least).
Ta
c6
Always good to get some things reinforced and learn some new stuff! I have made sure they know Rudder PAUSE check forward in that order is the start of recovery, but min. height loss dictates a rather rapid dive recovery without a secondary stall.
The bit about horses for courses and read the POH is also there, although I haven't spun many (C152, PA38 and DH82a) different recoveries.
Genghis - I have told them the difference between what we're doing here (in their spin recovery training for an instructor rating) and what they'll actually do in the a/c with Mr Uncoordinated is when it's the real thing they'll realise how little height they've got, and those magic three words will come back to them...
"I HAVE CONTROL"
Although if I can talk our committee into getting an aerobatic aeroplane over summer it will be much more fun (for me at least).
Ta
c6
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This is nowhere near complicated enough! How will the original question (or indeed answer)vary for:
a) Trimmable tailplane with elevator e.g. jet airliner
b) Fixed tailplane with elevator with trim tab e.g. Jet Provost
c) All-flying tail e.g. Gnat, Lightning (sigh)
As an aside, am I the only idiot who used to loop and barrel-roll a JP using the trim wheels?
Cheers
TP
a) Trimmable tailplane with elevator e.g. jet airliner
b) Fixed tailplane with elevator with trim tab e.g. Jet Provost
c) All-flying tail e.g. Gnat, Lightning (sigh)
As an aside, am I the only idiot who used to loop and barrel-roll a JP using the trim wheels?
Cheers
TP
There is an aircraft, built in this country, whose Dutch Roll characteristics are a function of the colour of the wing undersurface.
Having grasped that, it is easy to accept that on an aeroplane virtually any change, can affect virtually anything else.
I have seen stalling characteristics change due to trim-tab setting, weight, CG, deceleration rate, sail tension, introduction of a jury strut, etc. etc.
When considering a question like this, the only way to answer it is to work on the assumption that nothing else is changing at the same time.
G
Having grasped that, it is easy to accept that on an aeroplane virtually any change, can affect virtually anything else.
I have seen stalling characteristics change due to trim-tab setting, weight, CG, deceleration rate, sail tension, introduction of a jury strut, etc. etc.
When considering a question like this, the only way to answer it is to work on the assumption that nothing else is changing at the same time.
G
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Reversible controls
Ghengis/John,
I now understand what reversible controls are but why are they called that ?
Its a great word and I can just see all of those bar conversations starting "Of course when you have reversible controls....."
Ghengis, which aircraft is affected by its wing colour?
Excellent thread btw.
I now understand what reversible controls are but why are they called that ?
Its a great word and I can just see all of those bar conversations starting "Of course when you have reversible controls....."
Ghengis, which aircraft is affected by its wing colour?
Excellent thread btw.
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18greens
Perhaps because you (or the air) can operate them the reverse way from what one might expect. Like a car road wheel jerking the driver's steering wheel when it hits a curb.
Certainly irreversable controls cannot be moved in the reverse way. Come to that why are you called 18 greens.......
Perhaps because you (or the air) can operate them the reverse way from what one might expect. Like a car road wheel jerking the driver's steering wheel when it hits a curb.
Certainly irreversable controls cannot be moved in the reverse way. Come to that why are you called 18 greens.......
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John, Ah, Sound of hand hitting head!!
To a neophyte the word reversible controls conjurs up images of stick forward, houses get smaller, stick backward houses get bigger. It brings me back to the realistically possible nightmares of a glider with crossed control rigging.
As for 18 greens, well its better than 3... or none.
Thanks for the explanation.
To a neophyte the word reversible controls conjurs up images of stick forward, houses get smaller, stick backward houses get bigger. It brings me back to the realistically possible nightmares of a glider with crossed control rigging.
As for 18 greens, well its better than 3... or none.
Thanks for the explanation.