Where blade construction employs a bonding agent any strong washing solution can degrade the bonding material. This was a serious problem on Entrom F28 blades when cleaned by chemical cleaners.
Soap and water has always been the reccommended method.

And remember that clean rotor blades (main and tail) are necessary to obtain performance as given in the flight manual.

PA42

The concept of solar degrading of blades and cleaning agents causing debonding has been discussed on another thread ages ago with the Lu batting for the pro-degradation team.

My response was that we have hundreds of R22s and lots of R44s here in the hot dry Oz outback and there have been no rash of R22s dropping their wings off and only one R44 machine delaminating it's blades. Its a bit hard to blame an all pervading event as a cause for a problem in one machine.

The concern about cleaning agents is a bit harder to be sure of but some types of cleaner are commonly used and also have not been associated with widespread delamination.


Frinstance - Despite Lu's concern about good ol' WD 40 causing blades to fall apart left right and centre there were no actual reports of it ever being a cause. I actually have a letter from Patrick Cox (Robinson's cheif something or other (forget exactly what) saying WD 40 was fine to use except on the teflon parts of the stops and pitch rods. The letter is posted on my website if anyone wants to read it.

http://helipics.homestead.com and follow the technical links

In my own defense.
 

To: RobboRider



In my post regarding solar radiation I was responding to a post by Gaseous where he had commented about solar radiation and its' effect on Enstrom blades. I further expanded on that point telling about solar radiation and elastomeric parts on rotorheads. I was not specifically addressing Robinson blades.

In past posts I commented about the effects of certain detergents and how the alkaline elements in the detergent could cause hydrogen embrittlement. I also commented about the petroleum distillates in some waxes and its' effect on bonding agents. I further expanded on the use of WD-40 ® and the effects of the petroleum distillates on bonding agents.

I really don't care if Pat Cox authorized the use of WD-40 ® on Robinson blades because the manufacturers of WD-40 ® told me that they have not given any approval for its' use on any type of aircraft. This means that if something happens as a result of its' use your ass is left to hang out to dry.

WD-40 ® was developed as a water dispersal agent and not a rotorblade surface protector or a lubricant. Over the years it has been used for many applications due to its' ability to penetrate into very small openings. This could mean it can loosen a rusted bolt or in the case of a rotorblade it could penetrate into areas that could result in damage to the bonding materials.

WD-40 ® on blades can also attract and hold dust and dirt, which can effect the aerodynamic efficiency of the blades.

In making the above comments I am speaking as a Reliability engineer and addressing the above points relative to the ultimate safety of the equipment. I have been working in this capacity since 1968 so in making the above comments I am not shooting from the hip.

:E :E

100% corect Lu...

WD 40 is a water dispersant agent and yes it does attract dirt and degrade the aerodynamic efficiency of blades and is a possible cause of other maladays.

From years of experience I have found that WD 40 is OVERUSED and it is not the 'most wonderful stuff that will cure all ills'
Use it sparingly and clean off old WD 40 before applying a new.

I have found that after some time the WD 40 absorbs water and becomes sticky, so in small close fitteings it can gum up the works.
It's superb when fresh.

Robinson tail boom.
 

Do Robinson fit the tail rotor shaft bearing (the one on the damper), before riveting the boom together, or do they have workers with four foot long arms.?

I watched our mechanics fit one in with the tailboom already assembled. It was quite a chore using two mechanics, one spying through an inspection hole and knocking the (socket I believe) into the right location, and the other one at the end with the long pole. They have lock nuts on them which makes it much easier....that being said I am guessing the factory does it before riviting.

Robinson R22
 

Well after reading the entire forum regarding the Robinson R22 i am exhuasted LOL WoW!!

As an experienced Helicopter Pilot and having extensive experience on the R22 and R44 i just wonder if what Lu is telling us is True..!!!

I'm not an engineer, i'm that not clever, so i became a helicopter Pilot instead LOL, But i just can't help thinking Lu is correct and this has been a massive cover up from Robinson..

No wonder he has his money locked away off shore!
I was once told that Robinson is self insured.. what a joke! if you win you lose anyway!!

I once crashed in a R22, it bloody well hurts, The machine was a right off and according to BASI i am lucky to be alive! In fact shouldnt be!!

Before you ask, basi said it was Pilot error! I say it was LTE.
The aircarft would not recover and i crashed. ouch,,

Iv'e mustered in R22's and had them snapp at me and remind me who's boss, but i am still here.

But if Lu is correct in his theory and facts then this is a major cover up and should be exposed..

Safe Flying..what ever you fly!
:ok:

Rotaryman: It's very unlikely that you suffered LTE in a Robinson. The tail rotor of the R22, and even more so the R44, is exceedingly strong.
Don't get too worked up about what Lu says. He's nutty as a fruit cake. Toot toot!

rotaryman

When you've recovered your energy, you may find this thread of interest. It includes a post by Frank Robinson.

Click here.

Mr Selfish:
Be not afraidish.
The two most sensible suggestions that have been made in this entire debate come from Mr Nick Lappos, who was Sikorsky's lead test pilot on the S76, who now runs the S92 program, who is a lecturer in Newtonian Physics and an internationally-renowned consumer of Jim Beam.
These were that Lu Zuckerman should a) learn to fly, so that he might realise that helicopters do not do what he theorizes they will do when you wiggle the sticks, and b) that he should get some helicopter design qualification or experience, so that he might more closely understand some of the terminology he has picked up.
Lu's main claim to fame, that he once parked Arthur Young's car for him, doesn't fit the bill.

Making comments about someone you don't know is very bad form.
 

To: Pat Malone

Like they say, I’ll show you mine if you show me yours:

1) Maintained helicopters in the USCG
2) Attended six factory schools at Sikorsky
3) Attended 13 familiarization courses on other helicopters
4) Senior R&M engineer on the Cheyenne helicopter
5) Set up the Maintainability program on the Apache. Senior design for maintainability Engineer
6) Consultant on the integration of helicopters on ships
7) Maintenance manager for Bell Helicopter International
8) Set up and managed the R&M program for the Agusta A-129 and the EH-101
9) Consultant to the Director of Agusta regarding the integration of the Reliability and the Product support functions into the engineering process
10) Consultant on the V-22 program performing assessment of the maintenance activities on the structure.

This is just for helicopters. Do you want me to discuss the other programs I have worked on?

Regarding Arthur Young I never met the man nor, did I park his car as you so sarcastically noted. However I have an even bigger claim to fame. I knocked Igor Sikorsky on his ass at the old South Avenue plant.

Regarding your comment about me being nutty as a fruitcake I along with the other members of this forum would like to know what personal knowledge your comment was based on.

Did you talk to my wife?

:E :EOh yes, I completely forgot the fourteen month training program at Sikorsky which consisted of classroom studies and shop floor assembly of helicopters.

Lu: That must be about the tenth time you've posted your CV.

1. Learn to fly.
2. Get some design experience or qualification.
3. Come back and discuss it.

Mr Selfish

Frank Robinson's post in the certification thread was on the 30 November 2000.
I gave the date, rather than the page, because page numbers vary depending upon how we set up our user options.

Once agasin into the breech.
 

To: Pat Malone (Is pat short for Pastie?)

Lu: That must be about the tenth time you've posted your CV.[/QUOTE]
I have probably posted my abbreviated CV more than ten times. Each time I do it is in response to some idiotic statement by someone like yourself that I am uneducated in the ways of real pilots. That I have no understanding of the engineering that goes into the design of a helicopter and as a result I am in your words “Nutty as a fruitcake”. As far as my ability to fly helicopters or for that matter fixed wing aircraft my military experience include almost 300 hours at the controls of a helicopter and over twice that on fixed wing aircraft. I wasn’t trained to pilot standards but I could keep it in the air and I could land it if necessary.

It is obvious that you have no understanding of the function of a RMS engineer because if you did you would realize a RMS engineer is deeply involved in the design process. Whether the engineering department accepts the RMS engineers input is another story.

Now that I have shown you mine let's see yours. If you want to discuss Newtonian physics that is beyond my capability but if you want to discuss helicopters in general please do so.

:E :E

AMAZING..
 

I really find it amazing that people who claim to be Knowledgable, and shall we say, Inteligent!, HA!

Find it funny to verbally abuse a fellow PPrune member, LU is entitled to his oppinions, therories etc like the next guy!

I for one, would like to see some direct answers from Frank Robinson to Lu's Questions? instead of dancing around the Questions like he did.

I'm not an engineer as i have said before, But hey i'm a pilot and i think i understand helicopters etc, I have an open mind, i think! wow what if this guy is correct!

or are you so nieve to think there could never be any kind of cover up!! nah surley not!

:cool:

I think Lu wins this pissing contest...

The R22
 

What questions do you think need answering about the R22?

I've re-read Frank Robinsons post and it is very clear and accurate.

What is left to say?

CRAN

Reading it is not the same thing as understanding it.
 

To: CRAN

Re-read the part where he said he had considered a 90-degree phase angle but decided on the 72-degree phase angle. In order to have a 90-degree phase angle he would have to use a rotorhead like a Bell. However his whole design was predicated on the rotorhead that he had patented which had cone hinges. The use of this type or rotorhead eliminates the possibility of ever considering the application of a 90-degree phase angle. If he used a 90-degree pitch horn like on a Bell the helicopter would be uncontrollable.

My theory about the 18-degree offset was poo-pooed or downright ridiculed however I want you to consider the following: The aerodynamic theory of helicopter flight is that the blades will reach their maximum flap 90-degrees after the maximum pitch input. This is the way the flight controls are set up. Then there is phase angle shift, which means that due to outside influences the blades will not flap exactly at 90-degrees and the pilot will make cyclic corrections to compensate for this shift. The Robinson has according to everyone but me on this forum to include Frank Robinson a 72-degree phase angle.

Since the Robinson rotor system is rigged so that the blades do not receive maximum pitch input until the advancing blade is 18-degrees ahead of the lateral axis it must flap down over the nose in 72-degrees of rotation if it in fact has a 72-degree phase angle.

As an engineer you can diagram this action showing the tip path plane and the flapping of the advancing blade and by definition the retreating blade. If in flying in a helicopter you will note that the tip path is one continuous line interrupted periodically a blade flapping out of the tip path due to gusting and within one rotation it is back in the tip path. If the Robinson in fact has a 72-degree phase angle the tip path will not be one continuous line but it will show distinct deviation from the tip path plane and I would assume a lot of attendant vibration.

But what do I know as I am as nutty as a fruitcake.


:E :E

Understanding indeed
 

Lu,

Can you explain why you think a 90 degree phase angle would make the helicopter 'uncontrollable'.

Would it not just make it suffer from wee-wa and require the application of lateral cyclic as forward speed increases?

DC

Sorry kids, but while Lu is entitled to his opinion he is also a crackpot. His ludicrous theories have been rebutted by every genuine expert in the field on this forum, but his ever-wilder gyrations have kept us amused down the years, when he hasn't been banned for extra-crazy behaviour.
Unfortunately he sometimes frightens the kids, so it's necessary every now and then to point out that he is a buffoon with a fixation. He does not respond to logic or common sense (or even ridicule). He knows a little but talks a lot.
The R22 has now been flying for 29 years, and it is one of the safest helicopters ever, with a fatal accident rate better than most fixed-wings - currently 1.4 per 100,000 hours on NTSB statistics. Fly safely, and don't be taken in by Lu Zuckerman.

Now, I'm not only as nutty as a fruitcake I'm also a crackpot and a buffoon.
 

To: DrCopter

QUOTE]Can you explain why you think a 90 degree phase angle would make the helicopter 'uncontrollable'.[/QUOTE]

On the Robinson when it is at low pitch the pitch horn is coincident with the cone hinge so if you were to raise the blade pivoting on the cone hinge there would be no pitch flap coupling. However if you were to flap the rotor on the teeter hinge you would get some degree of pitch flap coupling.

With the rotor spinning and the pilot raises the collective the pitch horn/pitch link attachment would raise above the cone hinge. In this case when the blade flaps on either the cone hinge or the teeter hinge you would get pitch flap coupling. In this case the R-22 has a 72-degree pitch horn. If you had a 90-degree pitch horn the pitch horn would extend beyond the cone hinge and it would be coincident with the teeter hinge when the blades are at low pitch. If you were to teeter the blades in this condition you would get minimal pitch flap coupling however with pitch in the blades and if the blades coned you would actually increase the pitch over and above what you had put in with the collective and when the blades flapped about the cone hinge pitch would be input into the blade when it flapped up and removed from the blade when it flapped down. Pitch flap coupling on a conventional rotor system is the opposite. So with a 90-degree pitch horn what ever the pilot put into the blades the input would practically double and instead of having normal pitch flap coupling you would get the opposite.


To: Pat Malone

It seems that history is repeating itself. Ever since I expounded on my theories on the R-22 I was viciously attacked by RW-1 who challenged me on everything I said about the R-22 yet when I challenged him in return to tell me what exactly was wrong with what I was saying he never responded. It seems that you are doing the same thing but instead of a southern accent you are doing it with a Cornish accent. Just like RW-1 you refer to what other people say but never offer your technical opinions as to why I am wrong. Are you talking about my use of the term centrifugal force or, are you referring to my use of the term gyroscopic precession or are you talking about my theories on the R-22? Just what are you taking objections to and please tell me and the others what exactly am I saying that is wrong. I am not saying that I am right as they are theories but you are saying I am wrong.

Well what is wrong with what I have been saying?

Well?



:E :E

Mr. Malone

Your profile says that you are a publisher. Does your personalized attack have anything to do income, and the advertising that begets it?

Are you suggesting that those who are good at promoting helicopters are better people than those who are promoting good helicopters?

lu
 

i see what you mean, but just looking at the r44 from the ground you can see that the pitch links are closer to the mast slightly than the cone hinges and are closest to the cone hinge at full up collective. lift a blade up (make it teeter) and it donest change angle, maybe reduce pitch slightly as the pitch horn comes away from the centre. as i believe one blade cant flap up without the head teetering to equalization, they cant be affected individualy by your theory.
but all i could understand of the robinson waperwork is that the phase angle was made that way to reduce the cyclic neaded at translation and high forward speed.

ive been wrong before (thought i was wrong but i was right)

Lu said,

As an engineer you can diagram this action showing the tip path plane and the flapping of the advancing blade and by definition the retreating blade. If in flying in a helicopter you will note that the tip path is one continuous line interrupted periodically a blade flapping out of the tip path due to gusting and within one rotation it is back in the tip path. If the Robinson in fact has a 72-degree phase angle the tip path will not be one continuous line but it will show distinct deviation from the tip path plane and I would assume a lot of attendant vibration.


I often have trouble following Lu's posts but if I have this one worked it is just plain wrong.
Every time we track and balance blades his statement is shown to be wrong.

For those who may not know how its done:
Stick a dropdown tab on the end of each blade with a vertical reflective line on one and and a horizontal reflective line on the other.
Then - Up to the hover and strobe it and fly off at eighty knots and strobe it (with a strobe in the hand of passenger). The two reflectors are easily visible and various adjustments may or may not be needed to have them track so that the lines appear as a cross.
I have piloted machines for track & balance at least ten times
in the last three or four years and the whole idea is that when you fly it around it DOESN'T deviate from the tip path.
Even in gusts in doesn't deviate much and it comes back in line immediately.

Back to the drawing board, Lu.

You missed the point.
 

To: RobboRider

First of all what I said was in complete agreement with the above quote. The point I was trying to make has to do with a 72-degree phase angle on the Robinson. If it is in fact 72-degrees then the blade must respond to the maximum pitch input in order to get the maximum blade flap. If this is true then the blade must deviate from the tip path from a point 18-degrees ahead of the lateral axis in order to dip down over the nose with the opposite being true for the retreating blade.

It is for this reason that I presented my theory that the blade in fact would dip down 18-degrees to the left of the longitudinal axis (90-degree phase angle). And that in the process of correcting for inflow roll, transverse flow effect and dissymmetry of lift the pilot is moving the cyclic all over the place. And when everything settles down and the helicopter is flying straight the cyclic should be somewhere to the right of the rigged neutral position. To support my theory I have stated that if the cyclic is to the right of the rigged neutral position it may be there for several reasons including compensation for the 18-degree offset. Many of the respondents to my theory will state that this is to compensate for phase angle shift and completely discount the compensation for the offset. If I understand phase angle shift it will be some number of degrees less than the 90-degree phase angle built into the helicopter. If this is the case then the cyclic should be to the left of the rigged neutral position in order to compensate for the phase shift from 90-degrees which would cause the helicopter to fly to the right.

The design guidelines allow for several degrees of cross coupling so it is normal for all helicopters to experience this shift and it is acceptable in the certification process. Getting back to your statement relative to blade tracking I totally agree with you.


:E :E

Mr Jackson:
Lu and I are old sparring partners. I used to post on the forum under the name of Tain't Natural, and Lu and I had some fine old ding-dongs which I'm sure shed an enormous amount of light on this debate.
I have thought for some time that the camouflage of anonymity led me to say glib things about which I might be more circumspect if I were unable to hide, so I decided to post under my own name. Now I have to be extremely sure of my ground when I say Lu is a fixated monomaniac with a fetish, and 30 years of history, every truly expert opinion in the helicopter world and enough ridicule to kill a buffalo isn't going to change that.
But every so often he tries out his drivel on a new batch of ppruners, and there's a danger that some of them might be taken in.
Your notion of Robinson simply being good at promoting helicopters rather than promoting good helicopters is specious. I've followed your posts down the years and I have great respect for you. You usually do better than that.
None of my magazines have ever taken advertising from Robinson.

The mask is removed but the face is still the same.
 

To: Pat Malone ex t'aint natural

I couldn’t believe that there were two of you. From your profile you have a PPL (H) which means most of your helicopter time is in R-22s and you in no way would ever admit that there might be a problem in the design. A famous comedian once said that Denial is not just a river in Egypt.

You have a very low opinion of me as reflected in your comments in the above posts. I think every time you see my name on these forums you become apoplectic. Would it surprise you that I don’t even have any feelings one way or another when I see either your pseudonym or your real name. To me it is a game.

If you want to play the game you must play by the rules. The first rule is you do not have to accept what I say as fact but if you disagree you must counter my statement with a technical fact that proves me wrong. Rule number two is that you must not rely on other peoples statements about me relative to technical accuracy and making these statements to be fact (even if they are) instead you must prove me wrong by stating a technical fact.

If you do not want to play by the rules you can continue with your caustic comments and prove to the newbies to this thread that I am not to be trusted. You will also be proven to be another RW-1 but with an English accent. However, if you continue this way Heliport may jump you.

:E :E

Another clash of the Titans?
 

Could there be another Clash of the Titans in the near future? Stay tuned boys and girls... same Bat Time... same Bat Channel!

Honorable "Ah-Dee-Rik-Stah"

For those who've joined since and might not have seen the thread ......

Clash of the Titans

Lu,
What you spend most of your time doing is exhorting an explanation and then saying therefore lots of bad things must be happening.

Lets pretend for a minute that we have a scientific outlook to a situation.
First make an observation. THEN try and explain it.

Quote L.Z.
If the Robinson in fact has a 72-degree phase angle the tip path will not be one continuous line but it will show distinct deviation from the tip path plane and I would assume a lot of attendant vibration.

Real life situation:
Blades do not show distinct deviation and do not have a lot of attendant vibration.

Quote L.Z.
It is for this reason that I presented my theory that the blade in fact would dip down 18-degrees to the left of the longitudinal axis (90-degree phase angle). And that in the process of correcting for inflow roll, transverse flow effect and dissymmetry of lift the pilot is moving the cyclic all over the place.

Real Life Situation:
The cyclic does not need to be moved all over the place.

So now from observation we need to develop a theory Not the other way round.

Cart and horse Dilemma. Which comes first?
 

To: RobboRider

I stated that if in fact there were a 72-degree phase angle there would be a significant deviation from the tip path plane. I further stated in so many words that if there were in fact a 90-degree phase angle like in other helicopters the blades would dip down left of the nose with forward cyclic.

You stated: The cyclic does not need to be moved all over the place.

Now, I have a question. When you lift off do you make a cyclic correction to compensate for tail rotor translation? When you lift off single pilot do you make a correction to compensate for lateral CG displacement? When you are entering translational lift do you make any cyclic correction to compensate for transverse flow effect? When passing through translational lift do you make any cyclic corrections for dissymmetry of lift and attendant blowback?

I would assume that you answered yes to several of the above questions if not all. If you answered yes then the cyclic is being moved to compensate for the above conditions. Is there just a small possibility that you are also compensating for an 18-degree offset (if it exists) and you are totally unaware of it because at the end you are flying straight ahead?

Try this: The next time you go flying have your mechanic show you where the rigged neutral position is on the cyclic. In this position the swashplate is not tilted. Make note of the cyclic position. In forward flight keep the cyclic in the forward-displaced position and move the cyclic laterally to the rigged neutral position. If I am right the helicopter will fly to the left. If it doesn't deviate from the flight direction I am wrong and I will shut up. It is a simple test and could take all of 15 seconds.

Or, try this:

At your next start up place the cyclic in the rigged neutral position.
With the blades turning at 100% pull a slight amount of collective to get the blades to cone slightly. Move the cyclic forward from the rigged neutral position. Note what the blade disc does. Does it tip down over the nose or does it tip to the left. Another fifteen second test neither of which will place you or the helicopter in danger.

Am I right or, am I wrong? Take the time to prove your point and discount mine.

:E :E

Lu,

L.Z.
Left cyclic to compensate for tail rotor translation?

RR
Yes left lateral cyclic . But by your explanation I should be using foreward cyclic.

L.Z.
lift off single pilot … to compensate for lateral CG displacement?

R.R.
Yes lateral left cyclic and also forward cyclic because it hangs tail low when solo (but not when with Passenger). By your explanation I should be using foreward to compensate for the lateral CG and right for the tail low rearward drift

L.Z.
When you are entering translational lift .. any cyclic correction to compensate for transverse flow effect?

R.R.
Don’t recall any but I’d have to do it and take notice.

L.Z.
When passing through translational lift do you make any cyclic corrections for dissymmetry of lift

R.R.
Not that I recall but I’ll have to try and take notice.

L.Z.
and attendant blowback?

R.R.

Yes. Nose will pitch up noticeably if you don’t keep the cyclic forward. (Not to the right as your theory would suggest)


R.R.
Are there any helicopters (rigged in any way) that don’t have all these effects. I thought these were characteristics of pretty much all rotor discs. The cyclic movements aren't "all over the place" as your post would suggest.

I'll try it later in the week. I will try and get photos or video.

RR

Now we are getting somwhere.
 

To: RobboRider

The Robinson so I have been told has a very sensitive cyclic input
so moving the cyclic all over the place may be an over statement. However on most helicopters the movement is significant enough to be noticed (that is if your are looking for it).

On compensation for tail rotor translation I was not inferring that the cyclic would be moved forward.

Regarding rearward drift I would assume that you would compensate with forward cyclic. QUOTE: By your explanation I should be using forward to compensate for the lateral CG and right for the tail low rearward drift. UNQUOTE

I think your explanation is backwards. Forward for rear drift and lateral for CG placement.

Regarding for compensation for blowback: QUOTE Yes. Nose will pitch up noticeably if you don’t keep the cyclic forward. (Not to the right as your theory would suggest) UNQUOTE

I was addressing only the forward movement of the cyclic and not compensation for the offset. That is a problem in itself. The purpose of my post was to point out that the cyclic is under constant movement to compensate for the aerodynamic input into the rotor system.

[QUOTE]Are there any helicopters (rigged in any way) that don’t have all these effects. I thought these were characteristics of pretty much all rotor discs. The cyclic movements aren't "all over the place”, as your post would suggest. UNQUOTE

According to Frank Robinson the R-22 is not very susceptible to most of these conditions because it has a 72-degree phase angle
and according to him there is no phase angle shift. At least that is what I got out of his posting.

I will post on phase angle shift and perchance it will either enlighten some and infuriate others.

:E :E

:mad: and I thought reality tv was the most boring thing on Earth.


Until this kicked off.


Again.

Phase angle and phase angle shift
 

To: Anyone that will listen

The design requirements of the FAA dictate that the blades shall respond in the same sense as cyclic movement. It further states that even with the best design you are allowed to have several degrees of cross coupling. I would assume that this would be due to control geometry or aerodynamic influences (phase angle shift).

All helicopters have a design phase angle. This angle is 90-degrees. There is one exception and that according to Nick Lappos is the S-76 and it is not 90-degrees. You will have to get him to explain why. Also since I have no information on the BK series I can’t address the phase angle on those helicopters so we are stuck with Bell, Aerospatial and Sikorsky.

Now my definitions may be wrong but you will have to accept them as everything is predicated on these explanations.

Phase angle: The designed in control geometry that results in an angle of 90-degrees

Phase angle shift: The deviation from the 90-degree phase angle resulting from outside influences such as blade loading, air density, speed and any one of several other outside influences. This shift will result in the decrease of the 90-degrees to some figure less than 90-degrees.

Sikorsky helicopters have a 90-degree phase angle. The servos lead the direction of cyclic input by 45-degrees and the pitch horn leads the blade by 45-degrees. 45 + 45 = 90-degrees.

On two blade Bell helicopters the pitch horn leads or follows the blade by 90-degrees and the swashplate is displaced 90-degrees ahead of the blade.

On four blade Bells the pitch horn leads or trails the blade by 45-degrees and the swashplate displacement is 45-degrees. 45 + 45 = 90-degrees

On Aerospatial helicopters the pitch horn leads the blades by 60-degrees and the swashplate displacement is 30-degrees. 60 + 30 = 90-degrees. This may vary from model to model but the resultant is still 90-degrees

The Apache is much like the Sikorsky system.

The blades follow the swashplate movement in all cases and blade movement is as a result of Gyrodynamic Precession or Aeroscopic precession.

The Cheyenne was designed like the Sikorsky (45 + 45 =90-degrees) but the blades due to their aerodynamic shape and their stiffness never worked as designed. They got severe phase angle shift and the disc would not only move in a direction not commanded but they would diverge from the tip path plane and in certain cases would result in blade incursion. It took several years of design to get the blades to behave. This resulted in a sensing system being utilized to detect uncommanded movement and input was made to the main servo to make the blade move in the commanded position of the cyclic.

A similar system was incorporated on the Lynx. The Lynx is somewhat like the Robinson in that when rigging the helicopter the blade pitch is set with the blade 15-degrees ahead of the lateral axis. Without the protection of the black box the blades would dip down 15-degrees past the longitudinal axis when the cyclic was moved forward and because of the inherent stiffness in the rotor system this movement would be immediate.

Now, we get to the Robinson. Like the Lynx the blades have an offset but unlike the Lynx the Robinson is not effected like the Lynx. The Lynx has a 15-degree offset but a 90-degree phase angle. The black box adjusts the servo input so that when the cyclic is moved forward the servo input is adjusted to give 15-degree compensation to the right. The Robinson has an 18-degree offset but unlike the Lynx it has a 72-degree phase angle and according to Frank Robinson there is no need to make compensation for the offset. My god, that man is a genius.

So if the 15-degree offset is recognized by Westland and they compensate for it electronically then why doesn't the same apply to the R--22 and the 18-degree offset being compensated for by cyclic input.

It's Goose and Gander stuff the way I see it.


:E :E

Has anyone considered the human physiology aspect of this, and as such did FR come to the 18 degrees offset based on what felt "right" rather than any other design criteria. It cannot be contested that the offset is not a problem to pilots under normal circumstances.

It is some time since I flew a R22 but I remember that holding the cyclic with the left hand made control difficult. This is in marked contrast to my Enstrom which is often flown left handed with no difficulty, whilst adjusting mixture, radios etc. (Enstrom flown from left seat - no offset).

My point is , does the offset fit in with the natural movement of the shoulder and elbow joint of the right arm to make it feel right even though the disk is not moving in the same plane as the cyclic? Does the unique T bar control have any effect?

As we are keen on tests, get a protractor set up facing away from you. move your arm fore and aft not holding anything, resting on your knee, at 90 degrees to your body. Both joints must move. Then try moving it with 20 degrees offset and watch the joints. Which feels more natural?

Robinson don't rely on servos and electronics to nullify the offset. The pilots brain is trained to do it - until you try it left handed.

Could everybody be right?

FR may not like to admit that 18 degrees was arrived at by trial and error. That probably would not have convinced the FAA at the design stage.

Just a thought.

Gaseous you have a good point.

There is also the change in flight feel when switching to the left seat in a Robbo. If you just look at the cyclic geometry on the ground you'd think that it would operate in exactly the same way, but when you try to fly from the left seat for the first few times it is a very different machine.

Perhaps the 18 degree offset is the reason.

Moosp

I can't say I had noticed left seat problems in R22. If you do try left handed, maybe do it with another pilot onboard. Scared the sh1t out of me the first time I tried it. (hovering)

I think the reason it feels weird is just the fact that it attaches in between the seat. On the right side you feel all the friction on your left side cause that is where the cyclic is rigged. When you move to the left side you feel all the friction on the right side cause that is where the cyclic is rigged. "friction" may not be the best word but you get the idea. My opinion (which doesnt mean much)

Lu-Ill try your experiment tomorrow. I know the rigged position is already right of center on the 22 to compensate for translating tendency and I know if forward flight the cyclic is still off to the right of center, dont know if it is more or less though.