Wing drop at stall
I've spun a Hunter inverted. Enter at 30,000ft, 4 turns, recover, pull out from the dive - bottoms at about 15,000ft. Concentrated the mind on height loss - but as it's a swept wing jet massing around 10 tonnes, not all that representative of light GA typically massing about a tonne, with a propeller and a straight wing.
G
G
The bottom line from my POV. Any discussion of inverted spins have no relevance to the topic of stall/spin in ab initio training
As a general observation I would suggest failing to teach control of yaw and then failing to demand students control yaw in all phases of flight is a weakness in flight training. Unfortunately modern trainers, especially the C 172 will let students get away with feet on the floor flying. One result of this is effective control of yaw when the aircraft stalls and during the subsequent recovery. If yaw is controlled it is impossible for the aircraft to spin so failure to control yaw is not good.......
The bottom line from my POV. Any discussion of inverted spins have no relevance to the topic of stall/spin in ab initio training
G
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As a general observation an inverted spin will not happen in your typical GA trainer
You then say this should not be discussed in ab initio, unfortunately there are pilots that will try aeros without proper training, these are the ones most likely to mess it up and at least if it is discussed then they have some idea how to recover - also it is not a bad thing if they then go on to aeros to already know the principle, after all it is not that hard to teach - opposite rudder, stick progressively back OR forward until the spin stops! (Obviously just concentrating here on how little change you need to make rather than going through full spin recovery detail)
One of the few good things that have come out of EASA is the introduction of the Aerobatic rating. This at the least reminds pilots that they are not qualified to perform aerobatics until they are properly trained and assessed.
There is only so much you can do within the PPL syllabus before you overload it and possibly put people off flying. When I learnt to fly spinning was mandatory and many left flying because they would not accept the impending spin training or suffered an intolerable reaction to it. The current stalling syllabus is sufficient in its current form when it is completed fully. Sadly this is not always the case. As with some other parts of the syllabus stall training it is not completed, as detailed, but is only carried out sufficient to meet the requirements of the skill test.
There is only so much you can do within the PPL syllabus before you overload it and possibly put people off flying. When I learnt to fly spinning was mandatory and many left flying because they would not accept the impending spin training or suffered an intolerable reaction to it. The current stalling syllabus is sufficient in its current form when it is completed fully. Sadly this is not always the case. As with some other parts of the syllabus stall training it is not completed, as detailed, but is only carried out sufficient to meet the requirements of the skill test.
Foxmoth
I stand by my contention that the common trainers such as the C 152/C172 or Pa 28 series can’t enter an inverted spin as the significant wing dihedral makes them naturally unstable inverted so that they will transition into an erect spin on their own during the spin entry.
In the case of the C152 aerobat, my experience has been that even in full into yaw aileron and full power would not generate a stable inverted spin
The message for an initio student should not be how to deal with a botched hammerhead, it should be on the importance of reducing AOA to get the wing flying again and control of yaw to prevent a departure from controlled flight
I stand by my contention that the common trainers such as the C 152/C172 or Pa 28 series can’t enter an inverted spin as the significant wing dihedral makes them naturally unstable inverted so that they will transition into an erect spin on their own during the spin entry.
In the case of the C152 aerobat, my experience has been that even in full into yaw aileron and full power would not generate a stable inverted spin
The message for an initio student should not be how to deal with a botched hammerhead, it should be on the importance of reducing AOA to get the wing flying again and control of yaw to prevent a departure from controlled flight
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BPF, to be honest even a sustained erect spin is difficult to achieve in these aircraft, and I would certainly agree the emphasis should be on reducing AoA to get the aircraft flying, where I would disagree is your statement
, this certainly should not be discussed with all students as it will confuse, but anyone that has the interest and capability of understanding it should not be blocked from something that will expand their knowledge and understanding of stall/spin.
Any discussion of inverted spins have no relevance to the topic of stall/spin in ab initio training
The "Standard Spin Recovery" used as the start point for flight testing is found in AC23-8 and is opposite rudder, then stick forward. Whilst many aeroplanes may have variations from that, SSR is invariably the baseline.
G
Last edited by Genghis the Engineer; 24th Aug 2019 at 08:39.
Apologies Fox
Forgive a little thread drift. I just chanced upon a video of a float plane crashing on take-off due to a wing drop stall.
https://abcnews.go.com/WNT/video/vid...g-off-65157413
I realize that I have seen several videos showing similar crash on take-off, they seem to result from loss of power on take-off, but then no evidence of any attempt to lower the nose and deal with the issue. That float plane for example seemed to maintain a high AoA until it fell from the sky with one wing down. It looks like he had an entire lake to put it back down on but he didn't. If my interpretation is right, any thoughts on why this happens ? Does the pilot just freeze ? Or is there actually no time/authority to get the nose down at a critical point?
https://abcnews.go.com/WNT/video/vid...g-off-65157413
I realize that I have seen several videos showing similar crash on take-off, they seem to result from loss of power on take-off, but then no evidence of any attempt to lower the nose and deal with the issue. That float plane for example seemed to maintain a high AoA until it fell from the sky with one wing down. It looks like he had an entire lake to put it back down on but he didn't. If my interpretation is right, any thoughts on why this happens ? Does the pilot just freeze ? Or is there actually no time/authority to get the nose down at a critical point?
Last edited by double_barrel; 24th Aug 2019 at 11:05.
DB
Normal float plane takeoffs have the airplane becoming airborne at minimum flying speed so the drill is to become airborne and then accelerate in ground effect until climb speed is reached and then climb away. Float planes are more vulnerable to clumsy handling right at and after liftoff so you do see more stall accidents in this area compared to land planes. Gusty winds exacerbate the issue and require good skills to manage safely
Normal float plane takeoffs have the airplane becoming airborne at minimum flying speed so the drill is to become airborne and then accelerate in ground effect until climb speed is reached and then climb away. Float planes are more vulnerable to clumsy handling right at and after liftoff so you do see more stall accidents in this area compared to land planes. Gusty winds exacerbate the issue and require good skills to manage safely
In the ab initio context I demonstrate one spin as a way to show the consequences of not recognizing and avoiding the stall and if the airplane does inadvertently stall; not controlling yaw. The spin recovery is required if the airplane is actually spinning which on all common trainers, requires at least half a turn if not more. Recognition and avoidance of the stall should be the primary focus of ab initio training and instilling the instinctive reaction of froward stick full power and rudder to control yaw at the first sign of the aircraft stalling.
A very experienced test pilot, who became a flying instructor, referred to this in my hearing as "conducting the orchestra" - where pilots, instead of holding the controls firmly and initially in the pro-spin / initial condition, kept moving the stick around, and often didn't keep the rudder on the stop either. As you say, it creates interesting and inconsistent recoveries.
I agree that correct actions in the early incipient stage of the spin are not the same as those from a developed spin. Historically that basically was throttle closed/controls centralised. Interestingly, I explored that during some refresher aerobatic training last year, and the very experienced ex-military aerobatic instructor teaching me insisted that in his opinion whilst that worked consistently, he preferred the UPRT drill of unload in pitch / roll wings parallel with the horizon / pitch to level flight attitude.
So, what else could we do? We went and set up some deliberate gross mishandling upsets, and tried the two different recoveries with identical entries.
The result? Both worked first time every time, but his preferred UPRT approach gave us consistently about half the height loss. I am a convert!
G
I agree that correct actions in the early incipient stage of the spin are not the same as those from a developed spin. Historically that basically was throttle closed/controls centralised. Interestingly, I explored that during some refresher aerobatic training last year, and the very experienced ex-military aerobatic instructor teaching me insisted that in his opinion whilst that worked consistently, he preferred the UPRT drill of unload in pitch / roll wings parallel with the horizon / pitch to level flight attitude.
So, what else could we do? We went and set up some deliberate gross mishandling upsets, and tried the two different recoveries with identical entries.
The result? Both worked first time every time, but his preferred UPRT approach gave us consistently about half the height loss. I am a convert!
G
The full recovery from the spin was exactly as the POH (in this case for a T67M260), the UPRT - which we also used for an undefined early incipient spin (by undefined I mean from a manoeuver not a standard spin entry, and so with spin direction not yet defined) was as I've said above.
G
G
I'm still unclear Genghis what it is you are saying. I've attached the T67 Mark 11 spin recovery section albeit this aircraft has the less powerful 150/160 hp engine than the aircraft that you flew. I don't know if the recovery is different.
An issue for understanding for me could be the use of the word "incipient". In aerobatics the term covers the first 3-4 rotations or until the spin stabilizes. In the PPL syllabus the term applies to "wing drop" before rotation begins. There is a very important difference in the recovery technique between these two situations.
An issue for understanding for me could be the use of the word "incipient". In aerobatics the term covers the first 3-4 rotations or until the spin stabilizes. In the PPL syllabus the term applies to "wing drop" before rotation begins. There is a very important difference in the recovery technique between these two situations.
Now there's an argument I had with the late, great Darrol Stinton a few times. What is incipient?
Darrol used to reckon it was about the first 6 turns, and instrumented data I've been through from flight tests tends to agree with him - but the convention I am using here is that it is the phase between initial loss of control and the spin mode (e.g. erect to the left) becoming clear to the pilot.
G
Darrol used to reckon it was about the first 6 turns, and instrumented data I've been through from flight tests tends to agree with him - but the convention I am using here is that it is the phase between initial loss of control and the spin mode (e.g. erect to the left) becoming clear to the pilot.
G
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Equally, RAF Central Flying School now have quite a nice definition that works with my own students for defining incipient vs full spinning: an incipient spin is one that does not require a full spin recovery technique, while a full spin is one that does not recover using an incipient recovery technique. There is of course the caveat of individual aircraft having their own optimum recovery techniques - cf the farce of the Robin 2160 when first brought into the UK - but as an overall rule it works well. DS of course explored the various modes rather more thoroughly than most of us might in day to day flying, with more understanding of how differing flight path may affect the spin modes!
The robin 2160 gives pretty much the expected 'standard stall recovery' technique within it's POH. An interesting quote directly from it's manual: “Only one action is important – keep the rudder fully in opposite direction!”.
Following an interesting discussion with a number of aerobatic competition pilots I was surprised to hear that recovery from the incipient spin (most common during a short display) was primarily stick forward, I had to try this and found flying the R2160 that indeed by doing this you could recover well onto a very precise and predetermined heading. But what of using such a technique when recovering from a fully developed spin. I also tried this climbing to a safe height. I kept the spin to 6 rotations and then pushed the stick forward: it could have been set in concrete, it was immovable. I then applied maximum opposite rudder and was then, quite quickly, able to recover using the recommended POH spin recovery technique.
The R2160 manual also states that after 3 rotations the engine may stop but, this is not of concern because the engine will recover power quickly following recovery. The CAA did not like this so put in the restriction of a maximum of two turns. The engine stops very rarely but if it It does the POH is proved correct.
Following an interesting discussion with a number of aerobatic competition pilots I was surprised to hear that recovery from the incipient spin (most common during a short display) was primarily stick forward, I had to try this and found flying the R2160 that indeed by doing this you could recover well onto a very precise and predetermined heading. But what of using such a technique when recovering from a fully developed spin. I also tried this climbing to a safe height. I kept the spin to 6 rotations and then pushed the stick forward: it could have been set in concrete, it was immovable. I then applied maximum opposite rudder and was then, quite quickly, able to recover using the recommended POH spin recovery technique.
The R2160 manual also states that after 3 rotations the engine may stop but, this is not of concern because the engine will recover power quickly following recovery. The CAA did not like this so put in the restriction of a maximum of two turns. The engine stops very rarely but if it It does the POH is proved correct.