flight force
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"but will it fly?"
Now that's asking for too much.
If people have sympathy for Mr. Bell's and Mr. Robinson's difficulties in developing their teetering rotors, they should have the utmost compassion for poor Mr. Kaman. He had to do all of the above, and then, link two of darn things together.
Now that's asking for too much.
If people have sympathy for Mr. Bell's and Mr. Robinson's difficulties in developing their teetering rotors, they should have the utmost compassion for poor Mr. Kaman. He had to do all of the above, and then, link two of darn things together.
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to Lu Zuckerman: I followed the link and under Frank Robinsons comments it gave a summation of your position. In it you said that one of your fears was when a pilot encountered a low-g if they pulled aft cyclic they could exacerbate the roll.
ok so my first question is what would be the correct cyclic application? would it be to go slightly aft and slightly left cyctic? another thing that i have wondered is what an increase in the collective would do to reload the rotor? what are the problems that i havent foreseen with increasing the collective to reload the rotor.
ok so that was actually 2 questions but i have one more as well.
Why didnt robinson design the rotor system like the bell 2 blade heads?
all of the posts have been really informative and interesting, I appreciate any answers to my questions. thanks you
ok so my first question is what would be the correct cyclic application? would it be to go slightly aft and slightly left cyctic? another thing that i have wondered is what an increase in the collective would do to reload the rotor? what are the problems that i havent foreseen with increasing the collective to reload the rotor.
ok so that was actually 2 questions but i have one more as well.
Why didnt robinson design the rotor system like the bell 2 blade heads?
all of the posts have been really informative and interesting, I appreciate any answers to my questions. thanks you
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To: baranfin
The normal thing to do when encountering Zero G is to pull the cyclic to the rear. It was my contention that in order to fly straight ahead the cyclic would have to be displaced to the right of the rigged neutral position. This meant that there was a right roll component in the swashplate. If in encountering Zero G the pilot pulled aft cyclic he would exacerbate the right roll component generated by the tail rotor.
On a previous thread a post was made telling about a training program in the UK conducted by Tim Tucker. Mr. Tucker is somewhat of a consultant to Robinson and he conducts the safety courses for them. During the development of the R22 he was one of the test pilots. In that training program he told his students that when encountering Zero G they should pull the cyclic back and a “Tad” to the left in order to keep from adding to the tail rotor induced right roll. This is not what the POH states. It states that the stick should be brought back gently to the rear or, in the aft direction. I feel if that is done a low time pilot can lose the helicopter. If the stick is moved too far to the left when moving it aft the aircraft will encounter severe flapping loads and could possibly suffer rotor incursion or mast separation.
There is a possibility that if collective is added to load the rotor the increased drag could cause loss of rotor rpm but that is my opinion. Robinson designed the rotor head with cone hinges to reduce the bending loads on the blade from coning and flapping. If he used a Bell design type rotor the blades would have to be so robust as to add a great deal of weight to the airframe. I personally believe that all of the problems of the Robinson breaking up in flight would go away if they used a fully articulated three-blade rotor system similar to that used on the Sweizer 300.
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The Cat
The normal thing to do when encountering Zero G is to pull the cyclic to the rear. It was my contention that in order to fly straight ahead the cyclic would have to be displaced to the right of the rigged neutral position. This meant that there was a right roll component in the swashplate. If in encountering Zero G the pilot pulled aft cyclic he would exacerbate the right roll component generated by the tail rotor.
On a previous thread a post was made telling about a training program in the UK conducted by Tim Tucker. Mr. Tucker is somewhat of a consultant to Robinson and he conducts the safety courses for them. During the development of the R22 he was one of the test pilots. In that training program he told his students that when encountering Zero G they should pull the cyclic back and a “Tad” to the left in order to keep from adding to the tail rotor induced right roll. This is not what the POH states. It states that the stick should be brought back gently to the rear or, in the aft direction. I feel if that is done a low time pilot can lose the helicopter. If the stick is moved too far to the left when moving it aft the aircraft will encounter severe flapping loads and could possibly suffer rotor incursion or mast separation.
There is a possibility that if collective is added to load the rotor the increased drag could cause loss of rotor rpm but that is my opinion. Robinson designed the rotor head with cone hinges to reduce the bending loads on the blade from coning and flapping. If he used a Bell design type rotor the blades would have to be so robust as to add a great deal of weight to the airframe. I personally believe that all of the problems of the Robinson breaking up in flight would go away if they used a fully articulated three-blade rotor system similar to that used on the Sweizer 300.
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The Cat
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Lu :
Well remembered. I posted that bit about Tim Tucker's "aft and a tab left cyclic" some months ago, when this last came up.
To be fair, and I can't remember if this was in the original post, he added the "tad left" bit when he was talking about the test flying he'd undertaken exploring the low-G regime after several related accidents.
However, the POH says "aft cyclic" and unless you're very good, I'd go by that - after all, easier to pull straight back that have to add in a left component as well, and lesser mortals like me like the simple things in life.
Well remembered. I posted that bit about Tim Tucker's "aft and a tab left cyclic" some months ago, when this last came up.
To be fair, and I can't remember if this was in the original post, he added the "tad left" bit when he was talking about the test flying he'd undertaken exploring the low-G regime after several related accidents.
However, the POH says "aft cyclic" and unless you're very good, I'd go by that - after all, easier to pull straight back that have to add in a left component as well, and lesser mortals like me like the simple things in life.
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I haven't flown an R22 for several years, but I do know that you had to apply right cyclic in the cruie. However, whether this was a physical displacement or just a force, I don't recall. I wouldn't have thought there was any disputing this though as Mr Robinson has installed a simple trim system (bungee cord) to alleviate the strain on your wrist. That is hardly a secret.
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Another day in paradise
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Another day in paradise
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This technical stuff is very heavy going so is far from clear for me.
I fly R22 and R44 and can't say that I notice any problem with cyclic positioning. I certainly don't have to compensate 18 degrees to the direction I want to fly in. I push forward - it goes forward - I push left - it goes left etc... Next time I am a passenger in an R22/R44 I will take some digital pictures of the cyclic position in various flight modes and post them here. However I don't think this will prove anything because its where the cyclic feels right rather than looks right that the pilot is concerned about.
A further point - while hovering the R22 I feel there is no cyclic pressure in any direction however in forward flight there is a pressure to the left, which the pilot has to compensate for by pressure to the right. This becomes more intense the faster you go. Surely this is caused by the dissemmetry of lift and is why the cyclic trim is operated in forward flight? Could this be what Vorticey was referring to? Sounds like he is also confusing dissymmetry of lift with flap back too. Flapback requires the cyclic to be pushed thru more forward but not right. In the R44 Raven the hydraulic controls mask any cyclic pressure/vibration anyway but I do remember in training the force needed to hold the cyclic in position in forward flight with the hydraulics off.
(Now is a good time to remind R44 pilots to make sure the hydraulics are ON before you lift).
I fly R22 and R44 and can't say that I notice any problem with cyclic positioning. I certainly don't have to compensate 18 degrees to the direction I want to fly in. I push forward - it goes forward - I push left - it goes left etc... Next time I am a passenger in an R22/R44 I will take some digital pictures of the cyclic position in various flight modes and post them here. However I don't think this will prove anything because its where the cyclic feels right rather than looks right that the pilot is concerned about.
A further point - while hovering the R22 I feel there is no cyclic pressure in any direction however in forward flight there is a pressure to the left, which the pilot has to compensate for by pressure to the right. This becomes more intense the faster you go. Surely this is caused by the dissemmetry of lift and is why the cyclic trim is operated in forward flight? Could this be what Vorticey was referring to? Sounds like he is also confusing dissymmetry of lift with flap back too. Flapback requires the cyclic to be pushed thru more forward but not right. In the R44 Raven the hydraulic controls mask any cyclic pressure/vibration anyway but I do remember in training the force needed to hold the cyclic in position in forward flight with the hydraulics off.
(Now is a good time to remind R44 pilots to make sure the hydraulics are ON before you lift).
