Helicopter as easy to fly as plane
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Helicopter as easy to fly as plane
Consideration for a helicopter that is as easy to fly as a plane;
Characteristic:
~ How:
The ability to takeoff, perform flight maneuvers and land, without having to use the pedals.
~ Intermeshing configuration.
Immediate response to cyclic control inputs.
~ Extremely rigid rotors.
Minimal cross-coupling from cyclic control inputs.
~ No coning angle in rotor.
Minimal vibration.
~ No coning angle in rotors, plus additional blades.
On loss of power; automatic entry into glide slope (autorotation).
~ Rotor (not engine) governor.
Just provoking thought.
Characteristic:
~ How:
The ability to takeoff, perform flight maneuvers and land, without having to use the pedals.
~ Intermeshing configuration.
Immediate response to cyclic control inputs.
~ Extremely rigid rotors.
Minimal cross-coupling from cyclic control inputs.
~ No coning angle in rotor.
Minimal vibration.
~ No coning angle in rotors, plus additional blades.
On loss of power; automatic entry into glide slope (autorotation).
~ Rotor (not engine) governor.
Just provoking thought.
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And why would we want to make a helicopter EASY to fly 
Sure is fun letting an airline pilot anywhere near the controls.....makes them sweat.
Actually without an airplane licence I think I would rather struggle going the other way!!!!
But I don't think thats what you asked
Sure is fun letting an airline pilot anywhere near the controls.....makes them sweat.
Actually without an airplane licence I think I would rather struggle going the other way!!!!
But I don't think thats what you asked
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If you had asked if there was ever a helicopter that flew like an airplane (re. Control input, Control response and control neutralization the correct answer would be the AH-46 Cheyenne or its’ predecessors. On the Cheyenne the pilots did not have direct input into the rotor control system. Instead he moved a servo and the servo applied a spring load into the control gyro. The control gyro would respond due to gyroscopic precession and it would apply the control input into the pitch change horn. Once the rotor had reached its’ assigned position the pilot would neutralize his cyclic control much in the same way a fixed wing pilot would neutralize his controls after achieving the desired attitude. The control gyro however would maintain the commanded position due to its’ rigidity in space which maintained the original input from the pilot. The gyro however was not in the same plane as the disc.
[ 05 September 2001: Message edited by: Lu Zuckerman ]
[ 05 September 2001: Message edited by: Lu Zuckerman ]
Dave,
I must admit I am a little bit skeptical about having something that automatically puts you into autorotation - maybe it's just fear of the unknown, but I'd like to be the one initiating auto entry on recognition of power loss, rather than having the machine do it for me.
Obviously I want warning systems such as low rotor Rpm horns or whatever, but giving the aircraft the authority to put me in auto without me asking it to is, I feel, a bit too much automation.
Otherwise, good ideas!
PS another thing I just thought of - will there be a system to prevent attempted auto entry in case of power loss in the hover, for example? I'd hate to have the machine slam me into the ground because it was attempting to maintain rotor RPM at an inappropriate time.
[ 05 September 2001: Message edited by: Arm out the window ]
I must admit I am a little bit skeptical about having something that automatically puts you into autorotation - maybe it's just fear of the unknown, but I'd like to be the one initiating auto entry on recognition of power loss, rather than having the machine do it for me.
Obviously I want warning systems such as low rotor Rpm horns or whatever, but giving the aircraft the authority to put me in auto without me asking it to is, I feel, a bit too much automation.
Otherwise, good ideas!
PS another thing I just thought of - will there be a system to prevent attempted auto entry in case of power loss in the hover, for example? I'd hate to have the machine slam me into the ground because it was attempting to maintain rotor RPM at an inappropriate time.
[ 05 September 2001: Message edited by: Arm out the window ]
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To: Arm out the window
Back in the mid 1950s Sikorsky engineers tried to develop a system that used stored energy in a spring to force the collective down in the event of engine oil pressure loss. There was one major problem in that in order to cock the spring they used a hydraulic piston with the spring inside of the cylinder. The pressure was generated from the transmission driven hydraulic pump, which started to turn when the transmission started to turn. As speed built up the pressure was sufficient to cock the spring but in order to do that, the collective would have to rise due to the extension of the cylinder. This would increase pitch to the maximum but the blades were not turning fast enough so they would stall out due to inadequate lift and would hit the tail cone. The system fault was discovered by yours truly and I brought it to the attention of the hydraulics engineer who had no background in flight controls theory or aerodynamics. Two days later the test rig was removed and several days after that the engineer was let go.
Back in the mid 1950s Sikorsky engineers tried to develop a system that used stored energy in a spring to force the collective down in the event of engine oil pressure loss. There was one major problem in that in order to cock the spring they used a hydraulic piston with the spring inside of the cylinder. The pressure was generated from the transmission driven hydraulic pump, which started to turn when the transmission started to turn. As speed built up the pressure was sufficient to cock the spring but in order to do that, the collective would have to rise due to the extension of the cylinder. This would increase pitch to the maximum but the blades were not turning fast enough so they would stall out due to inadequate lift and would hit the tail cone. The system fault was discovered by yours truly and I brought it to the attention of the hydraulics engineer who had no background in flight controls theory or aerodynamics. Two days later the test rig was removed and several days after that the engineer was let go.
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It is natural to be skeptical of any device that has authority over the collective.
One does not wish to have the lift dumped while at a low altitude.
On the other hand if the collective is not lowered in an emergency, the rotors will slow and no good will come of it.
Perhaps the best thing would be to have a black box with enough smarts to know when to execute a cyclic flare to regain rotor speed versus when to lower collective.
It would have to know radar altitude , airspeed, rotor speed, vertical speed, heading, etc.
It would need to have control over collective, throttle, cyclic and anti-torque.
The pilot must be able to overide the sytem at any time, instantly.
If the system can be made reliable and reasonably light and inexpensive then it probably will be incorporated, just as the throttle governor has been made standard on the R22 (and on all turbine ships.)
Electronic flight systems are being developed that have astonishing abilties.
These can seen in small pilotless vehicles
that can fly themselves.
A Japanese helicopter designer has built a control system so adaptable that it can deal with the loss of a blade in flight!
No human pilot can make those calculations and millisecond responses.
At some point down the road we may not drive our own cars or fly our own aircraft.
We will strap into our autonomously controlled syncopters and read the newspaper while being delivered to our destination:
The Soilent Green production facility!
Floyd
One does not wish to have the lift dumped while at a low altitude.
On the other hand if the collective is not lowered in an emergency, the rotors will slow and no good will come of it.
Perhaps the best thing would be to have a black box with enough smarts to know when to execute a cyclic flare to regain rotor speed versus when to lower collective.
It would have to know radar altitude , airspeed, rotor speed, vertical speed, heading, etc.
It would need to have control over collective, throttle, cyclic and anti-torque.
The pilot must be able to overide the sytem at any time, instantly.
If the system can be made reliable and reasonably light and inexpensive then it probably will be incorporated, just as the throttle governor has been made standard on the R22 (and on all turbine ships.)
Electronic flight systems are being developed that have astonishing abilties.
These can seen in small pilotless vehicles
that can fly themselves.
A Japanese helicopter designer has built a control system so adaptable that it can deal with the loss of a blade in flight!
No human pilot can make those calculations and millisecond responses.
At some point down the road we may not drive our own cars or fly our own aircraft.
We will strap into our autonomously controlled syncopters and read the newspaper while being delivered to our destination:
The Soilent Green production facility!
Floyd
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To: Floyd Dan
I quote,” A Japanese helicopter designer has built a control system so adaptable that it can deal with the loss of a blade in flight!
No human pilot can make those calculations and millisecond responses”.
What exactly does it do? Does it place itself in a locked in position so that it would not be dislodged or harmed as a result of the subsequent imbalance and following crash?
Many years ago I was monitoring a class on the rotor system for the CH-37. The instructor was asked what would happen if a blade came off in flight. He replied that the rotor system being fully articulated would reposition the remaining blades on their drag hinges in order to compensate for the lost blade. On that particular helicopter the centrifugal loading on each blade was somewhere around 72,000 pounds. The millisecond response of the rotor system would be to tear the helicopter apart. Although the loading on smaller helicopters is much less the result of a blade loss would be the same. To my knowledge, there was only one helicopter that successful flew with only one blade and that was a helicopter concept tested by MBB.
I also heard of a Hughes LOH that had blade damage that made it difficult to fly. The pilot landed and removed the bad blade and its’ opposite in the opposed pair and with a lot of power and a lot of pitch he was able to return to base. However if the damaged blade separated in flight the pilot and the helicopter would both be dead.
I quote,” A Japanese helicopter designer has built a control system so adaptable that it can deal with the loss of a blade in flight!
No human pilot can make those calculations and millisecond responses”.
What exactly does it do? Does it place itself in a locked in position so that it would not be dislodged or harmed as a result of the subsequent imbalance and following crash?
Many years ago I was monitoring a class on the rotor system for the CH-37. The instructor was asked what would happen if a blade came off in flight. He replied that the rotor system being fully articulated would reposition the remaining blades on their drag hinges in order to compensate for the lost blade. On that particular helicopter the centrifugal loading on each blade was somewhere around 72,000 pounds. The millisecond response of the rotor system would be to tear the helicopter apart. Although the loading on smaller helicopters is much less the result of a blade loss would be the same. To my knowledge, there was only one helicopter that successful flew with only one blade and that was a helicopter concept tested by MBB.
I also heard of a Hughes LOH that had blade damage that made it difficult to fly. The pilot landed and removed the bad blade and its’ opposite in the opposed pair and with a lot of power and a lot of pitch he was able to return to base. However if the damaged blade separated in flight the pilot and the helicopter would both be dead.
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Back in the early 40's, the world's first production helicopter, the Flettner FL-282 came equipped with a rotor governor. It was totally mechanical and used a flywheel, but is said to have done the job quite well.
The FL-282 was also the first helicopter to transition between powered flight to autorotation and back to powered flight. However, the comments below do not mention if the pilot was able to override this minumum rpm after a loss of power, so that he could pull energy out of the rotor for a flare. It must be assumed that he could.
___________________
This following is an excerpt on the Flettner rotor governor.
"The collective pitch control was located adjacent to the throttle, so that both could be moved simultaneously if desired. The collective pitch lever did not actuate the collective pitch directly, but through the intermediary of a blade pitch governor.
The governor was coupled to a servo gear, which changed the pitch to correspond with the movement of the collective pitch lever. Movement of the lever, or of the governor, engaged one or other face of a clutch, which engaged a drive from the rotor to change pitch in the appropriate sense. A follow-up device disengaged the clutch when the pitch reached the correct new setting. The whole collective pitch range could be traversed in one second.
The governor was designed to control the rotor within 10 r.p.m. between full power and power-off conditions, and could be set to govern at any desirable minimum r.p.m. In early tests the governor was set for a minimum of 140 r.p.m., but in one case of power-off flight autorotation stopped and the aircraft hit the ground heavily. After this the governor was set to a minimum of 160 r.p.m. If the power unit failed, or the rotor r.p.m. were reduced to 160 by closing the throttle, the pitch was automatically reduced to that for autorotation.
The collective pitch lever allowed the pilot to override the governor and to adjust the pitch as he required, but he could only increase pitch when the rotor speed was higher than the governor minimum setting. He could not increase the pitch when the rotor r.p.m. were at the minimum. If the governor controlled the pitch erratically for any reason, the pilot could always override it by flying at low collective pitch. It only took charge when the rotor speed was dangerously low, and it was provided, therefore, not so much as an aid to the pilot in correlating pitch and throttle, but as a safety device."
[ 06 September 2001: Message edited by: Dave Jackson ]
The FL-282 was also the first helicopter to transition between powered flight to autorotation and back to powered flight. However, the comments below do not mention if the pilot was able to override this minumum rpm after a loss of power, so that he could pull energy out of the rotor for a flare. It must be assumed that he could.
___________________
This following is an excerpt on the Flettner rotor governor.
"The collective pitch control was located adjacent to the throttle, so that both could be moved simultaneously if desired. The collective pitch lever did not actuate the collective pitch directly, but through the intermediary of a blade pitch governor.
The governor was coupled to a servo gear, which changed the pitch to correspond with the movement of the collective pitch lever. Movement of the lever, or of the governor, engaged one or other face of a clutch, which engaged a drive from the rotor to change pitch in the appropriate sense. A follow-up device disengaged the clutch when the pitch reached the correct new setting. The whole collective pitch range could be traversed in one second.
The governor was designed to control the rotor within 10 r.p.m. between full power and power-off conditions, and could be set to govern at any desirable minimum r.p.m. In early tests the governor was set for a minimum of 140 r.p.m., but in one case of power-off flight autorotation stopped and the aircraft hit the ground heavily. After this the governor was set to a minimum of 160 r.p.m. If the power unit failed, or the rotor r.p.m. were reduced to 160 by closing the throttle, the pitch was automatically reduced to that for autorotation.
The collective pitch lever allowed the pilot to override the governor and to adjust the pitch as he required, but he could only increase pitch when the rotor speed was higher than the governor minimum setting. He could not increase the pitch when the rotor r.p.m. were at the minimum. If the governor controlled the pitch erratically for any reason, the pilot could always override it by flying at low collective pitch. It only took charge when the rotor speed was dangerously low, and it was provided, therefore, not so much as an aid to the pilot in correlating pitch and throttle, but as a safety device."
[ 06 September 2001: Message edited by: Dave Jackson ]
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There is apparently huge interest in developing an autorotation assist device.
here is a snippet of an article I found:
(Sugeno is a top scientist in Japan)
..As Sugeno explained, when a helicopter has an engine failure the
pilot must decide if he should (a) try to restart the engine, or (b)
abandon the attempt. In the latter case he must disconnect the engine
from the rotor to allow it to rotate freely and then dive forward in an
appropriate manner to generate force on the rotor to keep it spinning. If
this is done correctly, then near the ground he can straighten out and
there will be enough lift on the rotors to allow a safe landing. Sugeno
explained that all pilots must have this skill to obtain a license. A key
aspect of this is "autorotation entry," the period between straight
flight when the engine fails and initializing the dive, and that pilots
at Kawasaki told him they did not think it could be automated. However,
again using a fuzzy control system he claimed that it had been done, and
in fact was going to be installed on the company's large units. (We did
not obtain any of the details of the fuzzy rules.)
On a related
note, Sugeno explained that Kawasaki Heavy Industries has just begun a 6
year US$100M program to use this technology to develop a pilot-assisted
system for a large helicopter. If successful (and Sugeno believes that
scaling up will not be difficult, but admits that he has no direct
experimental evidence) such a system could be an excellent transition to
commercial applications without having to deal with the more difficult
problems associated with an unmanned unit.
Lu, I wish I could find a reference to give you on the helicopter stabilization system that I mentioned. I have a book published in '93 that says the system was tested succesfully on a 3 meter model and there were plans to test it on the real thing.
Floyd
here is a snippet of an article I found:
(Sugeno is a top scientist in Japan)
..As Sugeno explained, when a helicopter has an engine failure the
pilot must decide if he should (a) try to restart the engine, or (b)
abandon the attempt. In the latter case he must disconnect the engine
from the rotor to allow it to rotate freely and then dive forward in an
appropriate manner to generate force on the rotor to keep it spinning. If
this is done correctly, then near the ground he can straighten out and
there will be enough lift on the rotors to allow a safe landing. Sugeno
explained that all pilots must have this skill to obtain a license. A key
aspect of this is "autorotation entry," the period between straight
flight when the engine fails and initializing the dive, and that pilots
at Kawasaki told him they did not think it could be automated. However,
again using a fuzzy control system he claimed that it had been done, and
in fact was going to be installed on the company's large units. (We did
not obtain any of the details of the fuzzy rules.)
On a related
note, Sugeno explained that Kawasaki Heavy Industries has just begun a 6
year US$100M program to use this technology to develop a pilot-assisted
system for a large helicopter. If successful (and Sugeno believes that
scaling up will not be difficult, but admits that he has no direct
experimental evidence) such a system could be an excellent transition to
commercial applications without having to deal with the more difficult
problems associated with an unmanned unit.
Lu, I wish I could find a reference to give you on the helicopter stabilization system that I mentioned. I have a book published in '93 that says the system was tested succesfully on a 3 meter model and there were plans to test it on the real thing.
Floyd
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Lu
Your post about the AH-46 Cheyenne, and more significantly the postings on gyroscopic precession raises an interesting thought.
Dynamic stability of helicopters is an ongoing design consideration.
We also know that some aircraft instruments maintain an orientation in space by the use of two gyroscopes that rotate in opposite directions, on a common axis. The requirement for two counter-rotating gyroscopes is to cancel the 90-degree precession, of course.
Since helicopter rotors exhibit some gyroscopic precession, it would appear that coaxial helicopters, and to a lesser degree intermeshing helicopters, have a 'built in' damper on pitch and roll oscillations, which single rotor helicopters do not have.
[ 07 September 2001: Message edited by: Dave Jackson ]
Your post about the AH-46 Cheyenne, and more significantly the postings on gyroscopic precession raises an interesting thought.
Dynamic stability of helicopters is an ongoing design consideration.
We also know that some aircraft instruments maintain an orientation in space by the use of two gyroscopes that rotate in opposite directions, on a common axis. The requirement for two counter-rotating gyroscopes is to cancel the 90-degree precession, of course.
Since helicopter rotors exhibit some gyroscopic precession, it would appear that coaxial helicopters, and to a lesser degree intermeshing helicopters, have a 'built in' damper on pitch and roll oscillations, which single rotor helicopters do not have.
[ 07 September 2001: Message edited by: Dave Jackson ]
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To: Dave Jackson
I quote, “We also know that some aircraft instruments maintain an orientation in space by the use of two gyroscopes that rotate in opposite directions, on a common axis. The requirement for two counter-rotating gyroscopes is to cancel the 90-degree precession, of course”.
I am not aware of any aircraft instruments that have two gyro rotors rotating in opposition to each other to cancel out precession. The very nature of a gyroscopic type instrument is to precess when the aircraft attitude changes. It is the precession that causes the needle or little airplane to move showing the direction of movement.
Some satellites have gyros that rotate about a fixed axis. These gyros have a high moment of inertia and if there is any perturbing force the tendency to precess will impart a turning moment into the satellite structure causing it move in the desired direction.
I quote, “We also know that some aircraft instruments maintain an orientation in space by the use of two gyroscopes that rotate in opposite directions, on a common axis. The requirement for two counter-rotating gyroscopes is to cancel the 90-degree precession, of course”.
I am not aware of any aircraft instruments that have two gyro rotors rotating in opposition to each other to cancel out precession. The very nature of a gyroscopic type instrument is to precess when the aircraft attitude changes. It is the precession that causes the needle or little airplane to move showing the direction of movement.
Some satellites have gyros that rotate about a fixed axis. These gyros have a high moment of inertia and if there is any perturbing force the tendency to precess will impart a turning moment into the satellite structure causing it move in the desired direction.
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Lu
I believe that some attitude indicators, the instrument that functions as an artificial horizon, use counter rotation gyros.
The only reference to this on Alta Vista, was the following;
"Sometimes precession is unwanted so two counter rotating gyros on the same axis are used", from [How a gyroscope works] http://www.accs.net/users/cefpearson/gyro.htm
It also makes sense when you consider the event.
Consider two counter rotating gyros on a common vertical axle. When you pull the bottom of the axle toward you, the CCW rotating gyro will want to climb on the right-hand side whereas the CW rotating gyro will want to climb on the left-hand side. This duplex gyro will resist the imparted pitching force while at the same time it will not introduce a rolling moment.
[ 07 September 2001: Message edited by: Dave Jackson ]
I believe that some attitude indicators, the instrument that functions as an artificial horizon, use counter rotation gyros.
The only reference to this on Alta Vista, was the following;
"Sometimes precession is unwanted so two counter rotating gyros on the same axis are used", from [How a gyroscope works] http://www.accs.net/users/cefpearson/gyro.htm
It also makes sense when you consider the event.
Consider two counter rotating gyros on a common vertical axle. When you pull the bottom of the axle toward you, the CCW rotating gyro will want to climb on the right-hand side whereas the CW rotating gyro will want to climb on the left-hand side. This duplex gyro will resist the imparted pitching force while at the same time it will not introduce a rolling moment.
[ 07 September 2001: Message edited by: Dave Jackson ]
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Don't reaction wheels, as used on satellites and such, use two heavy spinning wheels to maintain rigidity in space? Is this what you're talking about Dave? As far as I know, regular vacuum instruments like AIs and DGs simply have a single spinning wheel...
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Dave,
I am wondering out loud here for a sec. You tout the synchrocopters ease of flight because torque is canceling itself out. However I just got in from a flight in the Huskie and after consideration I don't see how you will get away from some of the interesting flight characteristics exhibited by the type. For instance you must lead pedal before a cyclic input is made for a turn or you will find yourself well out of trim and doing wierd things. I also would like to point out that in certain flight modes pedal response is not responsive at all. Just a thought.
Brian
I am wondering out loud here for a sec. You tout the synchrocopters ease of flight because torque is canceling itself out. However I just got in from a flight in the Huskie and after consideration I don't see how you will get away from some of the interesting flight characteristics exhibited by the type. For instance you must lead pedal before a cyclic input is made for a turn or you will find yourself well out of trim and doing wierd things. I also would like to point out that in certain flight modes pedal response is not responsive at all. Just a thought.
Brian
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Kyrilian
You and Lu may very well be correct about aircraft instrumentation using only a single gyroscope. Perhaps flight instruments should not have been used as an example of counter rotating gyros. Thanks.
Brian (H-43)
Sounds like theory being put in its place by a dose of reality
The following are a couple of thoughts and your reply will be of value.
>For instance you must lead pedal before a cyclic input is made for a turn or you will find yourself well out of trim and doing weird things.<
From your experience with the Huskie, do you think that a longer tail boom, like the K-Max has, would improve the turns? Also it appears, theoretically at least, that a lot of the 'weird things" that take place with a helicopter are the result of the coning angle, which causes cross-couplings and flap-back etc. It is hoped that the incorporation of extremely rigid rotors will eliminate this coning angle. Thoughts?
>I also would like to point out that in certain flight modes pedal response is not responsive at all.>
It will really be appreciated if you could advice which mode(s) give the least response to pedal inputs.
You and Lu may very well be correct about aircraft instrumentation using only a single gyroscope. Perhaps flight instruments should not have been used as an example of counter rotating gyros. Thanks.
Brian (H-43)
Sounds like theory being put in its place by a dose of reality
The following are a couple of thoughts and your reply will be of value.
>For instance you must lead pedal before a cyclic input is made for a turn or you will find yourself well out of trim and doing weird things.<
From your experience with the Huskie, do you think that a longer tail boom, like the K-Max has, would improve the turns? Also it appears, theoretically at least, that a lot of the 'weird things" that take place with a helicopter are the result of the coning angle, which causes cross-couplings and flap-back etc. It is hoped that the incorporation of extremely rigid rotors will eliminate this coning angle. Thoughts?
>I also would like to point out that in certain flight modes pedal response is not responsive at all.>
It will really be appreciated if you could advice which mode(s) give the least response to pedal inputs.
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Dave,
I am treading into an area where I am not very qualified not an engineer or anything. As for the rigid rotors the only way to find out is to try and see in my opinion. Or maybe look more at the data from the FL 282. I can't speak from experience with the K-Max but I was flying with an former K-Max pilot today and he told me that it responds to the pedal/cyclic the same way as the Huskie. This also may have something to do with the servo flap control system but I don't think so. Also he said that the Huskie rotor cant of 11 degrees was more optimum than the K-Max 12.5 degrees of rotor cant in terms of maneuverability and control pressure.
As far a pedal unresponsiveness is concerned I really don't know how the K-Max is set up or how it flies. But the Huskie is unresponsive because it uses differential pitch to cause yaw. In an autorotation the requirements change so there is a mechanical reverser assembly that changes the direction of the differential pitch change pushrod. At a certain low point in its travel the reverser output rod will not move at all no matter what the deflection of the pedal input. This complicates thing during low power settings such as during a descent.
Even with theses interesting characteristics I still think that the Huskie is the easiest helicopter to fly that I have ever tried you just have to understand the differences. If you check out why the Marine Corps discontinued the use of the HTK-1 (Helicopter Trainer Kaman Model 1 - was an early Kaman synchrocopter) you will find one of the reasons was it was simply to easy to fly and cadets could not fly the "normal" helicopters that made up the advanced stage of training. Interesting bit of trivia anyway.
Brian
I am treading into an area where I am not very qualified not an engineer or anything. As for the rigid rotors the only way to find out is to try and see in my opinion. Or maybe look more at the data from the FL 282. I can't speak from experience with the K-Max but I was flying with an former K-Max pilot today and he told me that it responds to the pedal/cyclic the same way as the Huskie. This also may have something to do with the servo flap control system but I don't think so. Also he said that the Huskie rotor cant of 11 degrees was more optimum than the K-Max 12.5 degrees of rotor cant in terms of maneuverability and control pressure.
As far a pedal unresponsiveness is concerned I really don't know how the K-Max is set up or how it flies. But the Huskie is unresponsive because it uses differential pitch to cause yaw. In an autorotation the requirements change so there is a mechanical reverser assembly that changes the direction of the differential pitch change pushrod. At a certain low point in its travel the reverser output rod will not move at all no matter what the deflection of the pedal input. This complicates thing during low power settings such as during a descent.
Even with theses interesting characteristics I still think that the Huskie is the easiest helicopter to fly that I have ever tried you just have to understand the differences. If you check out why the Marine Corps discontinued the use of the HTK-1 (Helicopter Trainer Kaman Model 1 - was an early Kaman synchrocopter) you will find one of the reasons was it was simply to easy to fly and cadets could not fly the "normal" helicopters that made up the advanced stage of training. Interesting bit of trivia anyway.
Brian
