R22 down near Ely, Cambs: Jan 2012
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Thanks for a really informative reply topendtorque, the notion of fuel starvation to me seems quite eye opening, and looking at the accident site no fire seems intriguing.
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if you jam in left pedal by mistake at entry..... but as left goes in ac rolls left out of trim. relative airflow (plus stalling blades too??) creates a right rolling movement that inverts the aircraft.
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I've had a student do the wrong pedal on me on entry to auto in a 22, and it was extremely unnerving. Horn sounded and RPM dropped like a stone but I don't remember any roll. Recovery action (which came embarassingly late) was to stick the proper pedal in.
As part of the FI course you're taught to guard the stick and brace the pedal to protect against wrong inputs, but I guess after a few years I'd gotten a bit casual about it. If I remember there's a safety notice about it too.
However I have seen the EC120 demonstrate the opposite roll in response to pedal input under autorotation so it is possible.
As part of the FI course you're taught to guard the stick and brace the pedal to protect against wrong inputs, but I guess after a few years I'd gotten a bit casual about it. If I remember there's a safety notice about it too.
However I have seen the EC120 demonstrate the opposite roll in response to pedal input under autorotation so it is possible.
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R22
Steady on everybody. As far as I know I was the only pilot (FW) to witness this accident. Most of the stuff you have seen in the press is highly inaccurate but I will not make any comment until after the inquest. AAIB and the Police are still taking statements. Traumatic incident for everybody and our thoughts are very much with the family.
Muffin - generally in a helicopter, the secondary effect of yaw is roll in the same direction so in the example quoted it seems nigh on impossible to make it roll right when you have put in a bootfull of left pedal.
If you failed to lower the lever following an engine failure then any rotor stall would tend to start on the retreating side where the AoA is highest - that would give a pitch nose-up and roll left (on a counter clockwise rotor) so combining the 2 errors would seem to make it impossible to roll right.
The 'ususal' way of getting inverted in an R22 is during the low G pushover type manoeuvres, detailed in previous posts, where the only thing producing thrust that can affect the fuselage is the TR which then yaws the fuselage left followed by a roll (secondary effect) in the same direction.
If you failed to lower the lever following an engine failure then any rotor stall would tend to start on the retreating side where the AoA is highest - that would give a pitch nose-up and roll left (on a counter clockwise rotor) so combining the 2 errors would seem to make it impossible to roll right.
The 'ususal' way of getting inverted in an R22 is during the low G pushover type manoeuvres, detailed in previous posts, where the only thing producing thrust that can affect the fuselage is the TR which then yaws the fuselage left followed by a roll (secondary effect) in the same direction.
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now i may miss some bits or get it wrong, im only a fresh faced newbie, but as left goes in ac rolls left out of trim. relative airflow (plus stalling blades too??) creates a right rolling movement that inverts the aircraft
As far as recovery I would take a punt that the one I nearly saw kept rolling, pulling at least a bit of pitch and he had the power back on, but how much of an interruption was caused to power it as it went through upside down I don't know.
I saw it when he was still in a steep diving turn to the right, going at a fair clip heading 180 degrees from his original entry. So i "think' he initiated aft cyclic as he was rolling to the 270 degree mark. He continued the turn rolling left out of it and slowing, straight onto the pad. Then the instructor departed at VNE for the rest room.
As part of the FI course you're taught to guard the stick and brace the pedal
I agree austeriser, and we should keep the mood light and abstract, only pertaing to raised technical matters. I do hope every one is bearing up OK.
all the best tet
Feathering tickles - it would depend on how low the G was and exactly what the pilot was doing with the cyclic but yes it would roll left, unless the TR was much higher than the fuselage ie a lot of nose down - then it would have a moment arm about the fuselage to possibly create a right roll as well as the left yaw.
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Many thanks for the replies im sure many have enjoyed reading them. Bear in mind i was only refering to what i heard about the wrong pedal input on entry to an auto, and i may have either misunderstood, or misheard it. But, im sure i heard right, and to add clarity to the debate the conversation involved the left pedal input rapidly decaying rpm to stall point that i think only crab alluded to... i thought that stalling blades stalled and coned evenly, unlike say a retreating blade stall that stall on the retreating side only.
Il get my coat now.
Il get my coat now.
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Even though I knew who it was a few hours after it had happened, seeing my ex-instructor, colleague and friends' name in print in such circumstances is just horrid.
I've been in aviation for 15 years and known a few people who have died in accidents which are all very sad but this one has really got to me.
Thought's go to his wife and 2 young girls.
RIP Bob.
I've been in aviation for 15 years and known a few people who have died in accidents which are all very sad but this one has really got to me.
Thought's go to his wife and 2 young girls.
RIP Bob.
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stringfellow
Yes he did, but in your inexperienced state you should be careful in interpreting. The retreating blade may well stall as it is rolling quickly and thus confronting an increasing A/A- but I suggest not because only of the higher power required by the left pedal input dragging the RRPM down with the engine power curtailed after a period of time, say a second or so while everyone sits fat dumb and happy and waits for it to happen- and then, and then wait for it, here we go - yup, the aircraft rolls toward the stalled section of the disc. ho hum.
That is a nonsense. as had the RRPM gone so low for that to happen there would have been no hope of recovery whilst the RPM decayed further as it was rolling inverted.
What has happened according to two first person accounts each of whom suffered very little RPM decay as they are here to tell the tale, was the full left pedal set up a rolling moment, exacerbated violently and immediately by the fact that the advancing blade is now suddenly exposed to a change in direction of the relative airflow such that it is blown upwards as a rolling moment to join the previous T/R rolling moment to force the violent roll that is referred to. As an analogy I would liken it to a sheet of loose iron in a very gusty wind, when all of a sudden the edge of it is lifted a little to expose the underside to the gust and whoosh the iron flips udside down quicker-n-the-eye-can-see. Comprez?
To say that a recovery would be had by simply changing pedals is a nonsense, obviously that aircraft was already in a different configuration before the left pedal input. In the above two scenarios the left pedal was instantaneous and of full deflection, before the collective was put down.
yessir tha's right.
feathering tickles
WRT to crab's explanation of low G pushover rolling moments, I am sure he won't mind if I refer you to Robinson SN11, where it discusses a "powerful right rolling moment on the fueslage". You can look it up on the Robinson web site.
tet
and to add clarity to the debate the conversation involved the left pedal input rapidly decaying rpm to stall point that i think only crab alluded to...
That is a nonsense. as had the RRPM gone so low for that to happen there would have been no hope of recovery whilst the RPM decayed further as it was rolling inverted.
What has happened according to two first person accounts each of whom suffered very little RPM decay as they are here to tell the tale, was the full left pedal set up a rolling moment, exacerbated violently and immediately by the fact that the advancing blade is now suddenly exposed to a change in direction of the relative airflow such that it is blown upwards as a rolling moment to join the previous T/R rolling moment to force the violent roll that is referred to. As an analogy I would liken it to a sheet of loose iron in a very gusty wind, when all of a sudden the edge of it is lifted a little to expose the underside to the gust and whoosh the iron flips udside down quicker-n-the-eye-can-see. Comprez?
To say that a recovery would be had by simply changing pedals is a nonsense, obviously that aircraft was already in a different configuration before the left pedal input. In the above two scenarios the left pedal was instantaneous and of full deflection, before the collective was put down.
i thought that stalling blades stalled and coned evenly, unlike say a retreating blade stall that stall on the retreating side only.
feathering tickles
WRT to crab's explanation of low G pushover rolling moments, I am sure he won't mind if I refer you to Robinson SN11, where it discusses a "powerful right rolling moment on the fueslage". You can look it up on the Robinson web site.
tet
we now have four pages without a single fact
Rumour: a story or statement in general circulation without confirmation or certainty as to facts.
Just to clarify:
The R22 rolls right in a pushover (low G manoeuvre) because of the tail rotor thrust.
My mention of left roll was purely to highlight what happens if you stick a bootfull of left yaw in, either in normal flight or following an engine failure.
The AoA distribution on a rotor in forward flight means that the highest AoA is always on the retreating side - therefore if the blades are allowed to slow down, the stall will still occur here first because of the high AoA due to the lowest V squared on that side - blades will only cone up and stall together in a zero airspeed configuration (still wind hover).
The R22 rolls right in a pushover (low G manoeuvre) because of the tail rotor thrust.
My mention of left roll was purely to highlight what happens if you stick a bootfull of left yaw in, either in normal flight or following an engine failure.
The AoA distribution on a rotor in forward flight means that the highest AoA is always on the retreating side - therefore if the blades are allowed to slow down, the stall will still occur here first because of the high AoA due to the lowest V squared on that side - blades will only cone up and stall together in a zero airspeed configuration (still wind hover).
