Cyclic Back - Please Read
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Correct me if I'm wrong - still only inexperienced PPL (PF1 - I believe this still entitles me to post, even thouh I do not earn yet as a pilot, but i think professionalism is a manner in which you act - it is not your paycheque).
But I would have thought that the actions for engine failure would be similar whatever the type - Lower collectinve for safe RRPM, and aft cyclic to induce the airflow through the rotors. If neither are done, the autorotation will not be established. Forward airspeed can be adjusted in the auto - obviously depending on height available.
But I would have thought that the actions for engine failure would be similar whatever the type - Lower collectinve for safe RRPM, and aft cyclic to induce the airflow through the rotors. If neither are done, the autorotation will not be established. Forward airspeed can be adjusted in the auto - obviously depending on height available.
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Um, just my two pennies worth. I've taught on low and high inertia rotor heads (Gazelles to Seahawks) with basic and advanced students. I'm kinda against 'set piece' responses and IMHO, it is all about rotor energy management. Yes lower the collective (especially in low inertia systems) but then you have to really assess where the hell you are and how you want to arrive. A zero speed high ROD is preferable say into trees whereas, a run on would be fair on a grassy field or road.
I want to stress that these were done 'prewarned'. Use to practice engine offs in the Huey from almost any height and speed and it was a great machine....sometimes the response was to just lower the collective and accept a run on and other times, there was room to lower the collective and then get into a flare. High speed low level, cyclic back and lower collective during the flare and climb to height. But we practiced and practiced and even went with other instructors who would pull the engine anywhere anytime (but because you with the other instructor, you were expecting it).
Now in the Seahawk, we practice 'wait one two' before responding to a practice OEI....interesting to see the difference in performance compares to immediate response.
So much for my waxing lyrical.
I want to stress that these were done 'prewarned'. Use to practice engine offs in the Huey from almost any height and speed and it was a great machine....sometimes the response was to just lower the collective and accept a run on and other times, there was room to lower the collective and then get into a flare. High speed low level, cyclic back and lower collective during the flare and climb to height. But we practiced and practiced and even went with other instructors who would pull the engine anywhere anytime (but because you with the other instructor, you were expecting it).
Now in the Seahawk, we practice 'wait one two' before responding to a practice OEI....interesting to see the difference in performance compares to immediate response.
So much for my waxing lyrical.
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The article is absolutely right on the money. It shows the danger of using techniques (forward cyclic automatically) that appear to have been born in the mists of time and never questioned.
The other reason for not using forward cyclic is that when you flare, rotor RPM builds because the airflow through the disk is increased. If you push forward the airflow through the disk is going the wrong way and it will decrease rotor RPM.
I'm reminded of the old piston engine airline pilot who commented that he was always surprised when he reached the top of the climb and still had all the engines operating....
The other reason for not using forward cyclic is that when you flare, rotor RPM builds because the airflow through the disk is increased. If you push forward the airflow through the disk is going the wrong way and it will decrease rotor RPM.
I'm reminded of the old piston engine airline pilot who commented that he was always surprised when he reached the top of the climb and still had all the engines operating....
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I don't think the effect of airflow on the horizontal stabiliser has yet been mentioned.
I was taught that when the engine quits, reduced lift due to lowering the lever and low RPM causes descent and hence upward force on the rear stabiliser which causes a nose down attitude. Aft cyclic should be applied to counter this to maintain the autorotative angle of attack. Simply lowering the lever may not provide enough angle of attack if the RPM has fallen significantly. Sure, drag is reduced, but there must be an appreciable angle between the rotational airflow and the relative airflow. Pushing the cyclic forward reduces this vital difference in the two airflows.
Once the RPM is back in the green forward cyclic may be applied if there is time but that's gravy in the climb.
Forward cyclic with low rotor RPM is a recipe for disaster as this reduces the inflow angle required for autorotation.
My own experience suggests that tight turns are also effective at recovering RPM so maybe aft and sideways cyclic is indicated.
Any thoughts anyone?
I was taught that when the engine quits, reduced lift due to lowering the lever and low RPM causes descent and hence upward force on the rear stabiliser which causes a nose down attitude. Aft cyclic should be applied to counter this to maintain the autorotative angle of attack. Simply lowering the lever may not provide enough angle of attack if the RPM has fallen significantly. Sure, drag is reduced, but there must be an appreciable angle between the rotational airflow and the relative airflow. Pushing the cyclic forward reduces this vital difference in the two airflows.
Once the RPM is back in the green forward cyclic may be applied if there is time but that's gravy in the climb.
Forward cyclic with low rotor RPM is a recipe for disaster as this reduces the inflow angle required for autorotation.
My own experience suggests that tight turns are also effective at recovering RPM so maybe aft and sideways cyclic is indicated.
Any thoughts anyone?
Last edited by Gaseous; 24th May 2004 at 21:44.
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Gaseous,
steep turns will increase RRPM but with the expense of increasing ROD. Also when you roll out of the turn the RRPM will go back to where it was on the entry to the turn.
Someone mentioned they though the article was saying that aft cyclic was more important then down collective. I dont think that was the case. He did make the point that if the engine fails while fiddling with radios or whatever it may be, dont just reach for the collective to put it full down but reach for the collective while applying aft cyclic so that the RRPM wont decay as much while you take your one sec to get the collective full down. I believe the point they were making is that aft cyclic will slow rotor decay enough that you can safely lower the collective and maintain green on the scale.
steep turns will increase RRPM but with the expense of increasing ROD. Also when you roll out of the turn the RRPM will go back to where it was on the entry to the turn.
Someone mentioned they though the article was saying that aft cyclic was more important then down collective. I dont think that was the case. He did make the point that if the engine fails while fiddling with radios or whatever it may be, dont just reach for the collective to put it full down but reach for the collective while applying aft cyclic so that the RRPM wont decay as much while you take your one sec to get the collective full down. I believe the point they were making is that aft cyclic will slow rotor decay enough that you can safely lower the collective and maintain green on the scale.
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Jcooper
you said:
steep turns will increase RRPM but with the expense of increasing ROD. Also when you roll out of the turn the RRPM will go back to where it was on the entry to the turn.
I dont disbelieve you, and the ROD issue is beyond doubt but why should the RPM decrease as you roll out of the turn? It doesn't seem that way when I have tried it.
Also the ROD is greater with stalled rotors. We are really talking 'back to the wall' here.
I agree about lowering the collective. This is imperitive to reduce drag and loss of further RRPM. To not act immediately is not acceptable but while your hand is on the way there, get the stick back!!
you said:
steep turns will increase RRPM but with the expense of increasing ROD. Also when you roll out of the turn the RRPM will go back to where it was on the entry to the turn.
I dont disbelieve you, and the ROD issue is beyond doubt but why should the RPM decrease as you roll out of the turn? It doesn't seem that way when I have tried it.
Also the ROD is greater with stalled rotors. We are really talking 'back to the wall' here.
I agree about lowering the collective. This is imperitive to reduce drag and loss of further RRPM. To not act immediately is not acceptable but while your hand is on the way there, get the stick back!!
JC; I mentioned that the article appears to favour aft cyclic firs, and that worried me for the reasons above. I used RD Rickster's reply to back up the fact that the article has given that impression.
If the article was aimed ONLY at the Hughes models, perhaps it can be titled "Hughes Auto actions - not to be used in all types!"
Shawn - I am shocked that anyone would teach forward cyclic automatically. If the purpose of the article is to destroy that myth, then it gets my full support, however, I feel that the article convolutes this message by not continually emphasising RRPM. How you recover it could involve lowering the lever, aft cyclic, or steep turns and G loading the disc. I feel the article concentrates on only one of those aspects to the detriment of the message that RRPM is the goal, not aft cyclic!
Gaseous, I agree with your stabiliser comments on some machines however, have you ever done a UH-1H or B206 with floats. Again, the one solution of cyclic moving does not suit all situations. Use the cyclic to adopt the attitude you require: range, low speed, min RoD, turning, or RRPM recovery. Dont teach an automated resopnse that is limited to only specific situations. by the way: the RRPM will not increase/reduce much (roll induced drag changes aside) due to turning. What effects the RRPM far more noticeably is the G loading. When getting into the turn, G is applied, conservatin of angular momentum works, and RRPM increases. Rolling out of the turn itself will not reduce RRPM noticeably, but unloading the G when doing so WILL result in reduced RRPM (again due to conservation of angular momentum). The disc does not know it is in a turn.
I feel the article, and the majority of the responses are trying to say the same thing in many different ways - RRPM is LIFE. Do whatever you have to do to recover the RRPM, only then will you have control to worry about the other issues like airspeed, altidude and glide/flare distance. thus, what I said above:
RRPM is life fix it first - ie Maintain RRPM first,
Then maintain airspeed if possible,
only then maintain altitude if you have to.
Sacrifice altitude and airspeed in order to obey "RRPM is life"! Twins or singles.
in order to recover RRPM, use your tools: lower the lever and load the disc!
If the article was aimed ONLY at the Hughes models, perhaps it can be titled "Hughes Auto actions - not to be used in all types!"
Shawn - I am shocked that anyone would teach forward cyclic automatically. If the purpose of the article is to destroy that myth, then it gets my full support, however, I feel that the article convolutes this message by not continually emphasising RRPM. How you recover it could involve lowering the lever, aft cyclic, or steep turns and G loading the disc. I feel the article concentrates on only one of those aspects to the detriment of the message that RRPM is the goal, not aft cyclic!
Gaseous, I agree with your stabiliser comments on some machines however, have you ever done a UH-1H or B206 with floats. Again, the one solution of cyclic moving does not suit all situations. Use the cyclic to adopt the attitude you require: range, low speed, min RoD, turning, or RRPM recovery. Dont teach an automated resopnse that is limited to only specific situations. by the way: the RRPM will not increase/reduce much (roll induced drag changes aside) due to turning. What effects the RRPM far more noticeably is the G loading. When getting into the turn, G is applied, conservatin of angular momentum works, and RRPM increases. Rolling out of the turn itself will not reduce RRPM noticeably, but unloading the G when doing so WILL result in reduced RRPM (again due to conservation of angular momentum). The disc does not know it is in a turn.
I feel the article, and the majority of the responses are trying to say the same thing in many different ways - RRPM is LIFE. Do whatever you have to do to recover the RRPM, only then will you have control to worry about the other issues like airspeed, altidude and glide/flare distance. thus, what I said above:
RRPM is life fix it first - ie Maintain RRPM first,
Then maintain airspeed if possible,
only then maintain altitude if you have to.
Sacrifice altitude and airspeed in order to obey "RRPM is life"! Twins or singles.
in order to recover RRPM, use your tools: lower the lever and load the disc!
I don't think the effect of airflow on the horizontal stabiliser has yet been mentioned.
I was taught that when the engine quits, reduced lift due to lowering the lever and low RPM causes descent and hence upward force on the rear stabiliser which causes a nose down attitude.
I was taught that when the engine quits, reduced lift due to lowering the lever and low RPM causes descent and hence upward force on the rear stabiliser which causes a nose down attitude.
For memory, the small lip along the top of the leading edge of the B206 horizontal stabilizer was there to stall it in autorotation and reduce that tendency.
Would be interested if anyone can confirm that.
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Automatic responses to situations are, unfortunately, taught at the expense of thinking ahead and making the right decision. Often military training establishments are guilty of this because of the high number of students, and lack of control over the quality of instructors (I'm not trying to slam any particular military training establishments, but when the failure rate is less than 1% as it is in at least one very large military, you have to wonder...)
I remember talking to one instructor at an establishment that had just transitioned from the UH-1 to the Bell 206 for basic helicopter training. They were insisting that during a hovering engine failure in the Bell 206, you had to add forward cyclic because that was what you (supposedly) had to do in the UH-1. No amount of talking to them or suggesting that this was something they should try to see if they really needed it would convince them to change their way of doing things. So students would come from this course convinced that they needed to add forward cyclic in a hovering autorotation.
I think a lot of what this article was covering was an attempt to get people to think rather than just react automatically in a 'one size fits all' action.
I remember talking to one instructor at an establishment that had just transitioned from the UH-1 to the Bell 206 for basic helicopter training. They were insisting that during a hovering engine failure in the Bell 206, you had to add forward cyclic because that was what you (supposedly) had to do in the UH-1. No amount of talking to them or suggesting that this was something they should try to see if they really needed it would convince them to change their way of doing things. So students would come from this course convinced that they needed to add forward cyclic in a hovering autorotation.
I think a lot of what this article was covering was an attempt to get people to think rather than just react automatically in a 'one size fits all' action.
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The issue here is recovery from very low RRPM and it is a fact that the autorotative force (lift) on the disc is dependant on the angle of attack and velocity (rpm) squared, irrespective of helicopter type.
It is an aerodynamic fact that if you have low RRPM and forward cyclic is applied, the angle of attack is decreased, leading to less autorotative forceand more drag. If autorotative force is insufficient to overcome drag then the RRPM will decrease and the blade will stall which is what is suggested happened to the helicopters in the article.
Forward cyclic also unloads the disc which, as discussed above tends to lower RRPM. not good.
Aft cyclic is not about controlling attitue, speed or anything else at this time. It is about controlling inflow angle to give maximum autorotational force. RRPM is the only thing in life just now!
Tight turns load the disc and will cause increase in RRPM which crucially increases the efficiency of the autorotative 'engine' (remember the RPM squared bit) so conservation of angular momentum does apply but the increased autorotative force will more than offset this and on rolling out of the turn the RPM will not fall as much as expected. Agreed the disc does not know it is in a turn but it is working much better at higher RPM.
HOWEVER:
If RPM is low, increasing the inflow angle by any of these means may well cause more of the blade to stall if the critical angle is exceeded. If enough of the blade stalls, the drag goes massive and the RPM will fall further. In other words the disc will stall at a higher RRPM.
I can't find much info on recovery from very low RRPM but aerodynamically, a flare or tight turn seems not too bad an idea. If it causes blade stall you are probably really in trouble and will never know if not flaring was a better option.
better still, don't go there!
It is an aerodynamic fact that if you have low RRPM and forward cyclic is applied, the angle of attack is decreased, leading to less autorotative forceand more drag. If autorotative force is insufficient to overcome drag then the RRPM will decrease and the blade will stall which is what is suggested happened to the helicopters in the article.
Forward cyclic also unloads the disc which, as discussed above tends to lower RRPM. not good.
Aft cyclic is not about controlling attitue, speed or anything else at this time. It is about controlling inflow angle to give maximum autorotational force. RRPM is the only thing in life just now!
Tight turns load the disc and will cause increase in RRPM which crucially increases the efficiency of the autorotative 'engine' (remember the RPM squared bit) so conservation of angular momentum does apply but the increased autorotative force will more than offset this and on rolling out of the turn the RPM will not fall as much as expected. Agreed the disc does not know it is in a turn but it is working much better at higher RPM.
HOWEVER:
If RPM is low, increasing the inflow angle by any of these means may well cause more of the blade to stall if the critical angle is exceeded. If enough of the blade stalls, the drag goes massive and the RPM will fall further. In other words the disc will stall at a higher RRPM.
I can't find much info on recovery from very low RRPM but aerodynamically, a flare or tight turn seems not too bad an idea. If it causes blade stall you are probably really in trouble and will never know if not flaring was a better option.
better still, don't go there!
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The RRPM will drop back down to the point where it was before the turn. Go try 180s and you will see my point. Enter an auto, establish 65 knots and bottom of the green. Roll into the turn, hold 65 knots...the RRPM will increase the upper green (dont touch the collective). Finish the 180, roll out of the turn hold 65 knots, dont touch the collective, and watch the RRPM drop to the bottom of the green where it began.
I dont have some fancy physics explanation, but I do know observation.
I dont have some fancy physics explanation, but I do know observation.
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Jcooper.
This test is good but not quite testing the scenario we are discussing.
You are starting from a steady state of equilibrium so after the turn, if you alter nothing the equilibrium is bound to return.
Your test does prove that a turn increases the autorotational force to exceed the drag. If you watch your VSI you will see the penalty is an increased rate of descent. At the end of the turn you unload the disk, the autorotational force decreases and as the drag has not changed the RPM must fall. You have wasted the energy you put into the disk by keeping the drag high. Actually you get something back in reduced rate of descent until the equilibrium returns.
The scenario to test is
1) fat dumb and happy
2) Oh ****, I've got 75%RPM, loads of pitch on and no power
3)What do I do now?
Hint - The answer is not establish a steady state at 75% and then do a turn.
A more relevant test is to establish auto at the bottom of the green. Bottom the lever and see how quickly the RPM will rise to the top of the green with and without a turn. When you roll out of the turn the RPM will not drop unless you increase the drag with collective.
Remember that the intention is to recover RPM. You are not going to have the lever anywhere but glued to the floor if you have 75% RPM!
Also the difference in autorotational force is huge between the stalling point of the rotor and the bottom of the green (Lift proportional to RPM squared) so you are not getting anywhere near testing that aspect. Nor do you want to.
Point to take is if you can get RPM up near the green by doing a turn/flare, if you have the lever down the RPM will not go down again.
This test is good but not quite testing the scenario we are discussing.
You are starting from a steady state of equilibrium so after the turn, if you alter nothing the equilibrium is bound to return.
Your test does prove that a turn increases the autorotational force to exceed the drag. If you watch your VSI you will see the penalty is an increased rate of descent. At the end of the turn you unload the disk, the autorotational force decreases and as the drag has not changed the RPM must fall. You have wasted the energy you put into the disk by keeping the drag high. Actually you get something back in reduced rate of descent until the equilibrium returns.
The scenario to test is
1) fat dumb and happy
2) Oh ****, I've got 75%RPM, loads of pitch on and no power
3)What do I do now?
Hint - The answer is not establish a steady state at 75% and then do a turn.
A more relevant test is to establish auto at the bottom of the green. Bottom the lever and see how quickly the RPM will rise to the top of the green with and without a turn. When you roll out of the turn the RPM will not drop unless you increase the drag with collective.
Remember that the intention is to recover RPM. You are not going to have the lever anywhere but glued to the floor if you have 75% RPM!
Also the difference in autorotational force is huge between the stalling point of the rotor and the bottom of the green (Lift proportional to RPM squared) so you are not getting anywhere near testing that aspect. Nor do you want to.
Point to take is if you can get RPM up near the green by doing a turn/flare, if you have the lever down the RPM will not go down again.
Last edited by Gaseous; 25th May 2004 at 22:30.
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Shawn's reply regarding "formula" responses to emergency situations is spot on. As an experimental test pilot who has completed several certification H/V tests, hundreds of H/V validations, and thousands of autorotations with engine on and engine off in MD500/600 two and four bladed tail rotor and NOTAR series aircraft I have learned that the correct response is very much dependant on the initial conditions.
Appropriate application of cyclic is dependant on the variables forward speed, climb speed, height above the ground, and wind speed and velocity. The best general procedure in the MD500 is to maintain cyclic position until climb rate goes to zero and then decide if forward or aft cyclic is the appropriate response to the variables.
An engine failure at 3,000 Lbs GW, 50 KIAS, using 87.2 Q climb power at an altitude of 150 Ft. AGL will not turn out well if the pilot lowers the collective and uses moderate aft cyclic (which is the natural reaction of most pilots because this is the response for most autorotative entries in the 500 series helicopter).
There is a difference in extended glide with engine off or on. If in training you reduce rotor rpm to extend glide to the point that the rotor and N2 needles match, then you will get a 17 to 35 Hp push from the engine that you do not get when the engine has failed. The difference in glide can be significant at higher altitudes and long glides. Any autorotation where the main rotor speed remains above the N2 idle speed will be almost the same in practice or with the engine out.
The best method of avoiding climbout engine failure accidents is to use the take-off corridor profile in the H/V curve. Take-off profiles outside of that take-off corridor and within the avoid area, will create a situation where a hard landing will be almost unavoidable. The second practice that will improve the odds is be mentally prepared to immediately lower the collective at the first sign of a power loss. The third is to plan a route of flight that presents the most available landing area.
The circumstances of the two accidents are complex and it would be difficult if not impossible to draw comparative conclusions regarding the left side low landing attitude. Very low main rotor speed descents are difficult to characterize. Tail rotor controllability issues are often significant at main rotor speeds below the green arc and have some effect on fuselage impact angle just prior to very low rpm main rotor blade stall.
Appropriate application of cyclic is dependant on the variables forward speed, climb speed, height above the ground, and wind speed and velocity. The best general procedure in the MD500 is to maintain cyclic position until climb rate goes to zero and then decide if forward or aft cyclic is the appropriate response to the variables.
An engine failure at 3,000 Lbs GW, 50 KIAS, using 87.2 Q climb power at an altitude of 150 Ft. AGL will not turn out well if the pilot lowers the collective and uses moderate aft cyclic (which is the natural reaction of most pilots because this is the response for most autorotative entries in the 500 series helicopter).
There is a difference in extended glide with engine off or on. If in training you reduce rotor rpm to extend glide to the point that the rotor and N2 needles match, then you will get a 17 to 35 Hp push from the engine that you do not get when the engine has failed. The difference in glide can be significant at higher altitudes and long glides. Any autorotation where the main rotor speed remains above the N2 idle speed will be almost the same in practice or with the engine out.
The best method of avoiding climbout engine failure accidents is to use the take-off corridor profile in the H/V curve. Take-off profiles outside of that take-off corridor and within the avoid area, will create a situation where a hard landing will be almost unavoidable. The second practice that will improve the odds is be mentally prepared to immediately lower the collective at the first sign of a power loss. The third is to plan a route of flight that presents the most available landing area.
The circumstances of the two accidents are complex and it would be difficult if not impossible to draw comparative conclusions regarding the left side low landing attitude. Very low main rotor speed descents are difficult to characterize. Tail rotor controllability issues are often significant at main rotor speeds below the green arc and have some effect on fuselage impact angle just prior to very low rpm main rotor blade stall.
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Sorry Gaseous, mistaken on the situation.
But if the situation is fat dumb and happy...loads of pitch/power...engine fails (specifically takeoffs), the last thing you want to do is turn, keep the skids level. Rather hit hard upright, than softly in a turn
Your point is taken though
But if the situation is fat dumb and happy...loads of pitch/power...engine fails (specifically takeoffs), the last thing you want to do is turn, keep the skids level. Rather hit hard upright, than softly in a turn
Your point is taken though
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Here's my opinion...
a cyclic FLARE increases RRPM, regardless of speed. Concider this as a situation...
You are busy manually changing frequency and the engine dies (your hand not on the collective). Leading with a cyclic flare could (or will) assist in recovering RRPM until such time that you can lower the collective.
Therefore, during an engine failure after t/o, regardless of speed, FLARE. Just maintain SOME forward speed.
Again, my humble opinion.
a cyclic FLARE increases RRPM, regardless of speed. Concider this as a situation...
You are busy manually changing frequency and the engine dies (your hand not on the collective). Leading with a cyclic flare could (or will) assist in recovering RRPM until such time that you can lower the collective.
Therefore, during an engine failure after t/o, regardless of speed, FLARE. Just maintain SOME forward speed.
Again, my humble opinion.
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Jcooper
The idea is to roll out of the turn before you hit, however landing sites and all sorts of other variables count. On the other hand if the choice is land in a turn or with 8000 fpm ROD, NR at 0%and your aircraft and corpse spread thinly about, what is your choice then?
Autorotation is about energy management. A helicopter with a dead engine has 3 stores of energy.
1) potential energy (height)
2) kinetic energy (airspeed and to a lesser extent ROD)
3) more kinetic energy (RRPM)
The total energy in the system is more than is required to land safely, so the trick is to arrive at the ground with energy in the right place (RPM) and waste the excess (speed and height).
If RPM is low then a flare converts airspeed to RPM. A turn converts height into RPM.
A logical way to do this if RPM is low, other circumstances permitting, would be to turn high, to wind up the rotor system, converting height to RPM, without losing airspeed and save the flare for the end to counter the rate of descent.
Forward cyclic only has a place if you have RPM to spare as unloading the disc turns RPM into airspeed.
The idea is to roll out of the turn before you hit, however landing sites and all sorts of other variables count. On the other hand if the choice is land in a turn or with 8000 fpm ROD, NR at 0%and your aircraft and corpse spread thinly about, what is your choice then?
Autorotation is about energy management. A helicopter with a dead engine has 3 stores of energy.
1) potential energy (height)
2) kinetic energy (airspeed and to a lesser extent ROD)
3) more kinetic energy (RRPM)
The total energy in the system is more than is required to land safely, so the trick is to arrive at the ground with energy in the right place (RPM) and waste the excess (speed and height).
If RPM is low then a flare converts airspeed to RPM. A turn converts height into RPM.
A logical way to do this if RPM is low, other circumstances permitting, would be to turn high, to wind up the rotor system, converting height to RPM, without losing airspeed and save the flare for the end to counter the rate of descent.
Forward cyclic only has a place if you have RPM to spare as unloading the disc turns RPM into airspeed.
Rich Lee wrote:
(SNIP)
This is one of the best, most clear and concise posts I have ever read on PPRUNE. It ought to be required reading for every helicopter pilot.
Shawn's reply regarding "formula" responses to emergency situations is spot on. As an experimental test pilot who has completed several certification H/V tests, hundreds of H/V validations, and thousands of autorotations with engine on and engine off in MD500/600 two and four bladed tail rotor and NOTAR series aircraft I have learned that the correct response is very much dependant on the initial conditions.
This is one of the best, most clear and concise posts I have ever read on PPRUNE. It ought to be required reading for every helicopter pilot.
