Ditching a helicopter: (incl pictures)
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Lu
And so do I disagree with you - vehemently! As one who has experienced retreating blades stall, real time, in the classic case of trying to outrun a CB some 40 years ago (in a Sikorsky S51), I know that the first solid manifestation of the phenomenon is a violent pitchup of the nose FOLLOWED by a tendency to roll to the right. However, your not-so-ever alert young pilot - well-trained and anticipating the possible condition - was able to mimimize the roll with reduced collective and increased throttle - just as taught. I think you're caught up in the proverbial whirlwind of theorists talking to professionals who know, or have experienced, better, and you ought to cut bait before someone from ETPS or Patuxent River gets hold of you.
And so do I disagree with you - vehemently! As one who has experienced retreating blades stall, real time, in the classic case of trying to outrun a CB some 40 years ago (in a Sikorsky S51), I know that the first solid manifestation of the phenomenon is a violent pitchup of the nose FOLLOWED by a tendency to roll to the right. However, your not-so-ever alert young pilot - well-trained and anticipating the possible condition - was able to mimimize the roll with reduced collective and increased throttle - just as taught. I think you're caught up in the proverbial whirlwind of theorists talking to professionals who know, or have experienced, better, and you ought to cut bait before someone from ETPS or Patuxent River gets hold of you.
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To anyone still here. Should have read my first post TWICE before hitting the button. Obviously the rolling tendency was to the LEFT, not the RIGHT. Apologies to all.
Voljet
Voljet
Iconoclast
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To: Voljet and everyone else.
I stand corrected. I got it twisted around. The FAA Rotorcraft Flying Handbook Page 11-6 states: At the onset of retreating blade stall the helicopter will experience a low frequency vibration followed by the disc pitching up and the helicopter rolls to the left. Sorry if I got everyone upset.
On a personal note, you must be near my age if you were flying S-51s. My experience on those helicopters was between 1949 and 1952.
I stand corrected. I got it twisted around. The FAA Rotorcraft Flying Handbook Page 11-6 states: At the onset of retreating blade stall the helicopter will experience a low frequency vibration followed by the disc pitching up and the helicopter rolls to the left. Sorry if I got everyone upset.
On a personal note, you must be near my age if you were flying S-51s. My experience on those helicopters was between 1949 and 1952.
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Lu,
Further to my mind experiment with the vacuum, put the same rotor head in a heavier fluid than air, say water. If the rotor were to turn at the same speed as the rotor in air, and the vacuum, do you beleive the rotors will still respond as a gyroscope?
The forces acting on the blade will be greater and the stesses on the blade to overcome this stress would probably be so great as to destroy the blade. For a blade to be at its lowest point at the twelve o clock position, the blade would have to have its pitch changed much earlier than 90,(three o'clock)in order to give the blade time to overcome its stresses in time to acheive its lowest point at twelve o'clock.
This point could be at 100 degrees or 112.22 degrees,who knows, but it would have to be worked out for the stresses it undergoes. Do you think that the same rotor turning at the same speed in a heavier fluid than air is still a gyroscope?
Its a matter of designing blades with the fluid that you and I know as air, and the phase angle alone does not dictate automatically that it is a gyroscope. All spinning objects have the properties of a gyroscope, but aerodynamics or fluid dynamics, play a major role.
Nick or Grey Area, I would welcome your comments on my 'mind' experiment.
Im not an engineer, but studying the stuff at Uni.
Further to my mind experiment with the vacuum, put the same rotor head in a heavier fluid than air, say water. If the rotor were to turn at the same speed as the rotor in air, and the vacuum, do you beleive the rotors will still respond as a gyroscope?
The forces acting on the blade will be greater and the stesses on the blade to overcome this stress would probably be so great as to destroy the blade. For a blade to be at its lowest point at the twelve o clock position, the blade would have to have its pitch changed much earlier than 90,(three o'clock)in order to give the blade time to overcome its stresses in time to acheive its lowest point at twelve o'clock.
This point could be at 100 degrees or 112.22 degrees,who knows, but it would have to be worked out for the stresses it undergoes. Do you think that the same rotor turning at the same speed in a heavier fluid than air is still a gyroscope?
Its a matter of designing blades with the fluid that you and I know as air, and the phase angle alone does not dictate automatically that it is a gyroscope. All spinning objects have the properties of a gyroscope, but aerodynamics or fluid dynamics, play a major role.
Nick or Grey Area, I would welcome your comments on my 'mind' experiment.
Im not an engineer, but studying the stuff at Uni.
Iconoclast
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To: Sling Load
The situation that you describe is purely hypothetical however you do acknowledge that there would be increased forces that would damage the blades or, to totally destroy them. If we were to take this point one step further and say that the resistive forces were not present and the rotor could turn in water at 250-400 RPM then the cavitation would be so strong as to eat the blades within a moment or so.
I copied a part of one of my posts on the Phase Lag thread. It was in response to a claim that centrifugal force played no part in the operation of a helicopter rotor system.
“It’s is very nice to refer to engineering texts as a frame of reference but you have to understand that the author is making his own point and then he is creating the mathematics to describe the condition. However this situation would never be encountered in real life. While in school it gives you the ability to envision various situations but once you leave school you should close your text books and do it the way your employer tells you to do it”.
My point is that in setting up these hypothetical situations you have to take all things into consideration as well as that they must be demonstrable in order to prove the point of the hypotheses.
I don’t have the knowledge or technical background to properly answer your question. If you had indicated that it was a gyroscope under water then I would say that precession would take place and that the water might have a dampening effect and that there might be cavitation taking place which would increase the frictional forces on the surface of the spinning rotor and possibly cause pitting on the rotor which in turn would increase the frictional forces and on and on and on and........
The situation that you describe is purely hypothetical however you do acknowledge that there would be increased forces that would damage the blades or, to totally destroy them. If we were to take this point one step further and say that the resistive forces were not present and the rotor could turn in water at 250-400 RPM then the cavitation would be so strong as to eat the blades within a moment or so.
I copied a part of one of my posts on the Phase Lag thread. It was in response to a claim that centrifugal force played no part in the operation of a helicopter rotor system.
“It’s is very nice to refer to engineering texts as a frame of reference but you have to understand that the author is making his own point and then he is creating the mathematics to describe the condition. However this situation would never be encountered in real life. While in school it gives you the ability to envision various situations but once you leave school you should close your text books and do it the way your employer tells you to do it”.
My point is that in setting up these hypothetical situations you have to take all things into consideration as well as that they must be demonstrable in order to prove the point of the hypotheses.
I don’t have the knowledge or technical background to properly answer your question. If you had indicated that it was a gyroscope under water then I would say that precession would take place and that the water might have a dampening effect and that there might be cavitation taking place which would increase the frictional forces on the surface of the spinning rotor and possibly cause pitting on the rotor which in turn would increase the frictional forces and on and on and on and........
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Lu, the Cat
Mine was about a decade later, when the Canadian military was still using them as the RW conversion trainer at the Canadian Joint Air Training Centre in Rivers, Manitoba. I still have the 'winged S' imbedded in the palm of my right hand - but the old girl holds a big part of my heart - if you were good to her, she was more forgiving than any of the many types I've flown since - she did the sweetest downwind 'nap' autos I've ever seen, including 47s, 12Es and 206s. Maybe we could swap tales sometime.
Cheers, Voljet
Mine was about a decade later, when the Canadian military was still using them as the RW conversion trainer at the Canadian Joint Air Training Centre in Rivers, Manitoba. I still have the 'winged S' imbedded in the palm of my right hand - but the old girl holds a big part of my heart - if you were good to her, she was more forgiving than any of the many types I've flown since - she did the sweetest downwind 'nap' autos I've ever seen, including 47s, 12Es and 206s. Maybe we could swap tales sometime.
Cheers, Voljet
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Sling Load, without trying to guess at the precise final outcome, I think it's safe to say that you're right that the density of the fluid changes the dynamics.
Consider a gyroscope demonstration. You push down on the disk at 3 o'clock, 90 degrees later, at 12 o'clock, you see that part of the disk go down. When the disk moves, it must also move air. Which puts in a force downwards at 6 o'clock. Since the result of that forces appears to happen 90 degrees later, then it causes the disk to tilt slightly to the 3 o'clock. The net effect of all this tilting is that instead of tilting to the 12 o'clock, the disk tilts between 12 and 3 o'clock. The denser the air, the further from the 12 o'clock.
How much the disk tilts to the three o'clock depends on how strong the second order force is. Throw this experiment into water, and that force gets much stronger.
Now lets go on to helicopter rotors. If they're behaving like a gyroscope, then the result of a force appears to lag by precisely 90 degrees. Put the helicopter into water, and that hasn't changed. What has changed is that there is more than just one force on the blades.
If the helicopter doesn't act like a gyroscope, then the phase angle will still be affected by air density. The theories involved don't change, just the magnitudes of some of the forces on the blades.
Matthew.
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Consider a gyroscope demonstration. You push down on the disk at 3 o'clock, 90 degrees later, at 12 o'clock, you see that part of the disk go down. When the disk moves, it must also move air. Which puts in a force downwards at 6 o'clock. Since the result of that forces appears to happen 90 degrees later, then it causes the disk to tilt slightly to the 3 o'clock. The net effect of all this tilting is that instead of tilting to the 12 o'clock, the disk tilts between 12 and 3 o'clock. The denser the air, the further from the 12 o'clock.
How much the disk tilts to the three o'clock depends on how strong the second order force is. Throw this experiment into water, and that force gets much stronger.
Now lets go on to helicopter rotors. If they're behaving like a gyroscope, then the result of a force appears to lag by precisely 90 degrees. Put the helicopter into water, and that hasn't changed. What has changed is that there is more than just one force on the blades.
If the helicopter doesn't act like a gyroscope, then the phase angle will still be affected by air density. The theories involved don't change, just the magnitudes of some of the forces on the blades.
Matthew.
[email protected]
Great thread, pity i had to work and miss most of it.
Lu, Re retreating blade stall - we have been here done this. Last time we discussed this you agreed that:
a. The rotor disc does not become suddenly unstable.
b. The tail boom is in no danger of being struck.
c. the stalled blade in fact only has a portion of it stalled dependant upon its rotational position.
d. The blade does not rise up over the nose of the aircraft. this is not what causes the pitch up.
e. The stalling blade is still producing lift, despite sections of it being stalled.
Your repetition of this line of arguement merely adds credence to Nick's propostition that you have a hard time learning - it appears you have forgotten all the ground we made at that time.
The RBS thread was unfortunately closed so I cannot give you the examples. Did the Robinson Course thread also get closed? I cannot find it. Why did it get closed? We were making headway there too.
Basics (IMHO - I am not an aerodynamicist) for some of the stuff being discussed:
1. The blade disc will follow the fuselage with stick nuetral on a deck in motion. The disc is always attempting to align itself to the control position during positive G operations.
2. Didn't we previously agree that the rotor disc does not exhibit gyroscopic tendencies (or minimal at the most) because (amongst other things) it is not a rigid dis, rather the blades are free to flap independantly? This includes the Bell system. Lu: we agreed to the fact the Bell system allows individual blade flap in the Robinson thread.
3. Ditching is bad. Avoid exploration of the theories!
Good ditching stories: There was a B214ST ditching on video, I think it was from Northern Australia on a lloyd machine. old mate pulled off ditching. Pax egressed succesfully. Copilot used personal knife (not specially designed provided one) to cut life raft from aircraft. During vigourous knife application, poor bast ard copilot managed to spear left side float. Loud farting noise occurs as aircraft starts slow left roll. Captain yells expletive, decides to exit the right side of the cockpit and does beautiful 1/2 pike from his door opening as aircraft completes left roll and visits the ocean floor.
On the other extreme, a Russian KA26 Kamov ditched off Vladivostok due transmission problem. Floats worked, crew egressed and were rescued, ship sailed on, much vodka was drunk. 2 or 3 weeks later, said aircraft washes up on beach. New trannie fitted, and back to work it goes!
So I guess that the answer to "how long" will a float equipped aircraft last is like everything else in aviations - the answer is ...it depends!...
Lu, Re retreating blade stall - we have been here done this. Last time we discussed this you agreed that:
a. The rotor disc does not become suddenly unstable.
b. The tail boom is in no danger of being struck.
c. the stalled blade in fact only has a portion of it stalled dependant upon its rotational position.
d. The blade does not rise up over the nose of the aircraft. this is not what causes the pitch up.
e. The stalling blade is still producing lift, despite sections of it being stalled.
Your repetition of this line of arguement merely adds credence to Nick's propostition that you have a hard time learning - it appears you have forgotten all the ground we made at that time.
The RBS thread was unfortunately closed so I cannot give you the examples. Did the Robinson Course thread also get closed? I cannot find it. Why did it get closed? We were making headway there too.
Basics (IMHO - I am not an aerodynamicist) for some of the stuff being discussed:
1. The blade disc will follow the fuselage with stick nuetral on a deck in motion. The disc is always attempting to align itself to the control position during positive G operations.
2. Didn't we previously agree that the rotor disc does not exhibit gyroscopic tendencies (or minimal at the most) because (amongst other things) it is not a rigid dis, rather the blades are free to flap independantly? This includes the Bell system. Lu: we agreed to the fact the Bell system allows individual blade flap in the Robinson thread.
3. Ditching is bad. Avoid exploration of the theories!
Good ditching stories: There was a B214ST ditching on video, I think it was from Northern Australia on a lloyd machine. old mate pulled off ditching. Pax egressed succesfully. Copilot used personal knife (not specially designed provided one) to cut life raft from aircraft. During vigourous knife application, poor bast ard copilot managed to spear left side float. Loud farting noise occurs as aircraft starts slow left roll. Captain yells expletive, decides to exit the right side of the cockpit and does beautiful 1/2 pike from his door opening as aircraft completes left roll and visits the ocean floor.
On the other extreme, a Russian KA26 Kamov ditched off Vladivostok due transmission problem. Floats worked, crew egressed and were rescued, ship sailed on, much vodka was drunk. 2 or 3 weeks later, said aircraft washes up on beach. New trannie fitted, and back to work it goes!
So I guess that the answer to "how long" will a float equipped aircraft last is like everything else in aviations - the answer is ...it depends!...
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Heedm,
Yes, that is exactly the point of the hypothetical. The dynamics of a rotor in flight are very different from the vacuum and the water example.
In the vacuum the blades will probably respond sooner as there are no forces other than the linkage and friction. My point is, the rotor could be rigged at different phase angles to suit the design of the rotor system, I understand that rotors have the properties of a gyroscope, but gyroscopic precession in itself is not the explanation in total. Aerodynamics is the dominating force.
I had quite a lengthy hour and three quarters! discussion with a physicist on this subject (a relative) and he doesn't support the gyroscopic precession dominance at all. He stated the aerodynamics would overwelming be the dominant effect.
I have done aerodynamics at uni, but we havn't got into the helicopter aerodynamics,thats a way away.
I have disagreed with Lu on this before on so many other posts, and he knows that, all I can say is, I beleive Mr Robinson knows far more than Lu, and that he should address his concerns with them, or, go to the issuer of the TDC the FAA and explain it to them. Hes had some of the industries experts like Nick in total disagreeance with him and yet, this stuff still keeps him up all night. Mind you, my relo got quite excited about the discussion and it got my brain frazzled for a while,
Yes, that is exactly the point of the hypothetical. The dynamics of a rotor in flight are very different from the vacuum and the water example.
In the vacuum the blades will probably respond sooner as there are no forces other than the linkage and friction. My point is, the rotor could be rigged at different phase angles to suit the design of the rotor system, I understand that rotors have the properties of a gyroscope, but gyroscopic precession in itself is not the explanation in total. Aerodynamics is the dominating force.
I had quite a lengthy hour and three quarters! discussion with a physicist on this subject (a relative) and he doesn't support the gyroscopic precession dominance at all. He stated the aerodynamics would overwelming be the dominant effect.
I have done aerodynamics at uni, but we havn't got into the helicopter aerodynamics,thats a way away.
I have disagreed with Lu on this before on so many other posts, and he knows that, all I can say is, I beleive Mr Robinson knows far more than Lu, and that he should address his concerns with them, or, go to the issuer of the TDC the FAA and explain it to them. Hes had some of the industries experts like Nick in total disagreeance with him and yet, this stuff still keeps him up all night. Mind you, my relo got quite excited about the discussion and it got my brain frazzled for a while,
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Ditching
A curiosity question from fixed wing jockey.
I was pondering the other day the issue of ditching in a Helo.
Is there any standard approach to this? So you've auto-rotated down, splash, and you're goint to bail, but then there's those rotors still spinning above you, and you're sinking. Sounds a bit like a fish-bait scenario.
I remember studying the advice for fixed wing. Apart from not landing on the front of the wave or swell, it more or less said "cross your fingers".
I was pondering the other day the issue of ditching in a Helo.
Is there any standard approach to this? So you've auto-rotated down, splash, and you're goint to bail, but then there's those rotors still spinning above you, and you're sinking. Sounds a bit like a fish-bait scenario.
I remember studying the advice for fixed wing. Apart from not landing on the front of the wave or swell, it more or less said "cross your fingers".
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Ditching in a heli is a bit easier, depending upon the situation. You still have to look at swells, etc.
We look at it from two standpoints:
Whether we have power for it or not.
With power, most checklists have us come into a hover and the pax exit the aircraft, then we move off a short distance and put it in (gets pax away from the rotors).
Power off all remain with the craft.
As for your concern about the rotors up top, etc. At water entry typically lateral cyclic is applied in either situation, which will cause the blades to contact the water. Everyone waits until all motion has stopped before leaving the aircraft.
Since a majority of heli's have a high CG (engines and transmissions up top), most will then continue to roll inverted when submerged, one should be prepared for that. In my mil training, you grab a referance point and hold on to it if possible, and work your way thru your pre planned exit route hand over hand, never taking both hands off of the frame, etc.
For training did the dunker 4 times, 2 day, and 2 sim night with darkened goggles.
First runs everyone goes out thru their own exit.
Second runs everyone files out thru "Main cabin door"
(have to brief this among everyone just before they dunk you)
Dunkers were certainly one of the fun things about training, serious business, but fun never the less
We look at it from two standpoints:
Whether we have power for it or not.
With power, most checklists have us come into a hover and the pax exit the aircraft, then we move off a short distance and put it in (gets pax away from the rotors).
Power off all remain with the craft.
As for your concern about the rotors up top, etc. At water entry typically lateral cyclic is applied in either situation, which will cause the blades to contact the water. Everyone waits until all motion has stopped before leaving the aircraft.
Since a majority of heli's have a high CG (engines and transmissions up top), most will then continue to roll inverted when submerged, one should be prepared for that. In my mil training, you grab a referance point and hold on to it if possible, and work your way thru your pre planned exit route hand over hand, never taking both hands off of the frame, etc.
For training did the dunker 4 times, 2 day, and 2 sim night with darkened goggles.
First runs everyone goes out thru their own exit.
Second runs everyone files out thru "Main cabin door"
(have to brief this among everyone just before they dunk you)
Dunkers were certainly one of the fun things about training, serious business, but fun never the less
Last edited by RW-1; 8th Apr 2002 at 16:01.
Paulo: Options are very limited.
Most ditchings are uncontrolled where the pilot becomes a passenger. If you do have any available control/power over the helo, then the above is true. Get rid of your pax because the chances of you getting out safely are slim. Be very careful about "lateral movement" of the cyclic prior to going in.
If you offer the retreating blade into the water first, there is a good chance that the gearbox and or engine(s) will smack you in the back of the head
If you are mister cool and think you have your wits about you you might be tempted to offer up the advancing side first which dismounts the heavy metal behind and above you...rearwards
If I was to put it into the water again for my second time then I would kick the doors offprior to landing and settle it gently onto the water, then prey!
If you aren't ex mil, I won't go into the abandon aircraft drill, but if you do a lot of over water, i would suggest a 'dunker' course (£180+) at Fleetwood or similar for the experience which you will come to rely on and never forget!.
When most choppers ditch (controlled) they role over and sink nose first, putting you inverted pointing away from the surface and in the dark...nice...
Stay feet dry....
Most ditchings are uncontrolled where the pilot becomes a passenger. If you do have any available control/power over the helo, then the above is true. Get rid of your pax because the chances of you getting out safely are slim. Be very careful about "lateral movement" of the cyclic prior to going in.
If you offer the retreating blade into the water first, there is a good chance that the gearbox and or engine(s) will smack you in the back of the head
If you are mister cool and think you have your wits about you you might be tempted to offer up the advancing side first which dismounts the heavy metal behind and above you...rearwards
If I was to put it into the water again for my second time then I would kick the doors offprior to landing and settle it gently onto the water, then prey!
If you aren't ex mil, I won't go into the abandon aircraft drill, but if you do a lot of over water, i would suggest a 'dunker' course (£180+) at Fleetwood or similar for the experience which you will come to rely on and never forget!.
When most choppers ditch (controlled) they role over and sink nose first, putting you inverted pointing away from the surface and in the dark...nice...
Stay feet dry....
Iconoclast
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Back in 1949 the US Coast Guard attempted to determine the best method of ditching a helicopter. Having access to twelve surplus HOS-1 helicopters the pilot took them up in succession and dumped them into the Albamarl Sound just off Elizabeth City, NC. After all of the ditchings were completed the final report indicated that the helicopter should enter the water in a normal attitude and then the pilot would move his cyclic to the left causing the retreating blades to hit the water. In a previous post it was indicated that the gearbox may hit you in the back and this may be true in today’s helicopters. In the test helicopters the blades were not as robust as the blades on today’s helicopters and in the ditching process the blades just disintegrated upon hitting the water.
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helicopter ditching
paulo: best trick, have emergency floats installed before going out over water, and then do not be afraid to use them at the first sign of trouble. repack/ recharge is cheap considering the consequences.
chp dr
chp dr
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Just a thought, some of the experts out there might be able to help more....
What about in the auto (assume engine failure) at the last moment before contact with the water giving the chopper aft cyclic to try and get the tail rotor in the water first to try and slow down the main rotor a bit to reduce the problem mentioned above about the gearbox smashing through to the pilot.
What about in the auto (assume engine failure) at the last moment before contact with the water giving the chopper aft cyclic to try and get the tail rotor in the water first to try and slow down the main rotor a bit to reduce the problem mentioned above about the gearbox smashing through to the pilot.
Iconoclast
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Dipping the tail rotor in the water would slow the main rotor down for a mili second at which time the tail rotor and gearbox would be torn away from the tail cone and the drive shaft would suffer a great deal of damage..
There was a case where a pilot mistook a river for the active runway and he set his H-300 down in the water. When the tail rotor hit the water the drive shaft wound up torsionally, severely shortening it and the diaphragm couplings stretched to make up the difference caused by the torsional shortening of the shaft. The diaphragm couplings then separated from the gear drive and the tail rotor gearbox and the helicopter came to rest on the river bottom. As an aside the pilot sued Hughes for the damage to the drive line..
There was a case where a pilot mistook a river for the active runway and he set his H-300 down in the water. When the tail rotor hit the water the drive shaft wound up torsionally, severely shortening it and the diaphragm couplings stretched to make up the difference caused by the torsional shortening of the shaft. The diaphragm couplings then separated from the gear drive and the tail rotor gearbox and the helicopter came to rest on the river bottom. As an aside the pilot sued Hughes for the damage to the drive line..
The Original Whirly
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Thomas, or anyone,
Do you have any details of where to do a dunker course. It sounds like a really good idea. Just reading this thread sends shudders through me - I've read about what to do and I remain unconvinced about any of it. I think some practice would be sensible.
Please could you e-mail me any info, as I'm off to the US tomorrow and may not have internet access for three weeks; it'll save me remembering and hunting for this thread when I get back.
Thanks a lot, and bye for now.
Do you have any details of where to do a dunker course. It sounds like a really good idea. Just reading this thread sends shudders through me - I've read about what to do and I remain unconvinced about any of it. I think some practice would be sensible.
Please could you e-mail me any info, as I'm off to the US tomorrow and may not have internet access for three weeks; it'll save me remembering and hunting for this thread when I get back.
Thanks a lot, and bye for now.
It's not just an adventure....
it's just a job!
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WRT Ditching:
There are three primary considerations:
1. Flight Conditions ie. IMC/VMC
2. Time of Day, ie. Day/Night
3. A/C Type.
Condition 1 and 2 will determine the flare height and amount of flare at the bottom, ie Night or IMC would dictate a flare at approximately 150' with 10 degrees of flare. Day VMC would require a flare at 100' upt to 25 degrees of flare(over land) but over water, the IMC tequnique is recommended do to loss of visual cues.
Condition 3 will determine the touch down. In the S76, it is recommended that you hold 10 degrees nose up until touch down with the floats deployed through 500'. In the 212 it is recommended that you actually drag the T/R through the water, this has nothing to do with slowing the blades, rather it provides a certain amount of stability to the A/C while deploying the floats after touch down.
Depending on the sea state/ Wind combination, the use of these techniques can lead to a successful ending. Having never ditched (full on auto to water) its hard to say, but having ditched in training (waterbird training in CYAW) it is the way I'll go.
Cheers OffshoreIgor
There are three primary considerations:
1. Flight Conditions ie. IMC/VMC
2. Time of Day, ie. Day/Night
3. A/C Type.
Condition 1 and 2 will determine the flare height and amount of flare at the bottom, ie Night or IMC would dictate a flare at approximately 150' with 10 degrees of flare. Day VMC would require a flare at 100' upt to 25 degrees of flare(over land) but over water, the IMC tequnique is recommended do to loss of visual cues.
Condition 3 will determine the touch down. In the S76, it is recommended that you hold 10 degrees nose up until touch down with the floats deployed through 500'. In the 212 it is recommended that you actually drag the T/R through the water, this has nothing to do with slowing the blades, rather it provides a certain amount of stability to the A/C while deploying the floats after touch down.
Depending on the sea state/ Wind combination, the use of these techniques can lead to a successful ending. Having never ditched (full on auto to water) its hard to say, but having ditched in training (waterbird training in CYAW) it is the way I'll go.
Cheers
OffshoreIgor
Join Date: Apr 2002
Location: oceanside
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inflating emergency floats after touchdown,is for the float systems i have personally installed or been involved with testing, not considered standard procedure, emergency floats should be inflated before contacting water.
chpr dr
chpr dr
Join Date: Jan 2001
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Whirlybird,
The Civy dunker courses are done at Marine Colleges around the UK. They started doing them for the offshore industry. Living in Wales your best bet is Fleetwood Nautical/Marine College. I know of other courses at Aberdeen, Yarmouth, Southampton (Warsash). They do them in the military too, of course, but you normally have to wear a funny colour flying suit.
The Civy dunker courses are done at Marine Colleges around the UK. They started doing them for the offshore industry. Living in Wales your best bet is Fleetwood Nautical/Marine College. I know of other courses at Aberdeen, Yarmouth, Southampton (Warsash). They do them in the military too, of course, but you normally have to wear a funny colour flying suit.