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Robinson R44

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Robinson R44

Old 14th Jun 2007, 11:52
  #901 (permalink)  
 
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I don't think he's talking about locking the cyclic friction fully on, just a tad to ease stick movements.
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Old 14th Jun 2007, 15:18
  #902 (permalink)  
 
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Ah, we've been throught this before.

Many helicopter pilots like the loose, zero-feedback, "wet-noodle" feel of hydraulically assisted cyclics. They feel that any sort of friction at all detracts from their ability to control the ship smoothly, and that "no friction" allows them to make those necessary imperceptible control movements, especially in the hover. Maybe so.

But as the original poster declared, flying in rough air (yes, even hovering in rough air) can cause inintended cyclic movements, no matter how hard you try to prevent them. Think of it this way: *ANY* movement of the cyclic moves the swashplate a commensurate amount. If you move the cyclic 1/8th of an inch, the swashplate moves. Can 1/8th of an inch cause a diversion from "in-trim" flight? Of course!

Now, think of the pilots you know who use no friction at all. If you look at the cyclic in the hands of such pilots, it is almost constantly moving. Oh, the movements may be tiny, but it *is* moving, more than would appear to be "necessary." See it for yourself next time you fly!

My personal belief is that these tiny, unnecessary, unintended movements of the cyclic cause the overall ride quality to deteriorate. Pilots will argue this vehemently. All I can say is that I've spent a lot of time flying with other pilots over my 31-year career, and this is my observation. Personally, I use "some" friction on the cyclic where it is available.

Now, nobody in their right mind would suggest locking a flight control when the aircraft is in the air, or even applying so much friction that movement of the control is impeded. That would be lunacy. So I use just enough friction to give the stick some "break-out force" and drag. I use enough to keep the cyclic from moving if I loosen my grip or release it. I use it to dampen out unintended movements. Experimentation helps.

As an airplane pilot too, I know that flying an airplane with zero friction on the controls would be a difficult, fatiguing experience. (Try flying a simulator with no springs or any kind of dampening device on the primary control stick/wheel.) Why we helicopter pilots elect to do so when there is an alternative is beyond me. I've never understood it. But every pilot is different; to each his/her own.

My advice: If cyclic friction is available, use it.
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Old 14th Jun 2007, 15:31
  #903 (permalink)  
 
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Hairyman,
I choose not to - for the simple reason that you never know when another whisk, a plank, a blimp, a bimbling engineless (radioless) plank, microplank or bloke with a parachute and big desk fan strapped to his back might violate your airspace and require a bit of rapid wrist action for avoidance.
I have had to do this on the odd occasion with far too little warning to go loosening frictions.

Most trips I do are 10-25 mins max so it doesn't get too tiring. I have 650 hrs (200 in R22 and 450 in R44 Clipper II)

SB
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Old 14th Jun 2007, 15:31
  #904 (permalink)  
 
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FH1100 Pilot;
Spot on!
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Old 14th Jun 2007, 15:51
  #905 (permalink)  
 
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You're missing the point, nobody is suggesting cranking the friction on so tight you need to fight it, just a fraction to reduce the slop.

I've lifted a 44 with all the frictions on and it's no fun! (Actually, not true, for those watching it was a lot of fun apparently....)
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Old 14th Jun 2007, 17:29
  #906 (permalink)  
 
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An R44 with hydraulics will fly hands off if you give it the chance. There may be some unintended roll, but it stays level for at least 10 seconds.
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Old 14th Jun 2007, 17:51
  #907 (permalink)  
 
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OK I'll try it on the way home tonight - if you don't hear from me again it's been nice talking to everyone here at PPRuNe and whatever you do don't turn up the cyclic friction.

Just kidding, I may tweak the knob a tad and see how I get on this evening (and I may adjust the friction also...).

An oscillation dampening tightness is all that is being proposed rather than a frozen stick rigidity.


SB
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Old 14th Jun 2007, 18:26
  #908 (permalink)  

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Depends on the #ship.

Personally I don't like cyclic friction on in anything.

Collective friction, every time.

But some 44's have a very tight Col friction setting that precludes a quick lowering.Personally I like it set so I can lower through the friction if needed but where it is quite tight to do so.

h-r (flown about 25 different R44's)
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Old 14th Jun 2007, 18:26
  #909 (permalink)  
 
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The problem of using cyclic friction on helicopters with powered controls but no artificial trim is that there is then a break out force; so once the cyclic is moved, it tends to be moved too far.
Collective friction ok in moderation so that turbulence doesn't disturb the setting, but probably better removed for the hover for same reasons as above.
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Old 14th Jun 2007, 19:07
  #910 (permalink)  
 
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I am 100% for using cyclic friction, esp. in the R44. Repeating what FH1000 said, in slightly bumpy air, the cyclic will move quite a bit, no matter how much the pilot tries to keep it still.

The way I apply cyclic friction is this: takeoff without friction, then after takeoff, move the cyclic slightly fore and aft (about an inch or so) while applying cyclic friction to the point where the resistance feels comfortable. Cyclic friction is of course, adjustable, there is not just 'on' and 'off'. I like to fly with quite a bit of friction, it does not impede my controlability of the helicopter at all. It makes flying in turbulence a lot more comfortable.

When using the friction, there should simply be an increase in the resistance when applying cyclic input, but there is no apparent 'break' force to move the cyclic.

Sometimes I land with the cyclic friction on, it feels only slightly different.
Even when flying the AS350, I like to use some cyclic friction on that ship to stabalize the cyclic.

All this not because I cannot control the cyclic, but again, with very sensitive hydraulic controls, it only takes a tiny amount of pressure to move the cyclic, and any movement that is not nessasary is a waste.
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Old 15th Jun 2007, 11:01
  #911 (permalink)  
 
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Cyclic friction

Sorry, the word 'collective' was an error in my post. In my machine the colective stays put unless a 'wider' pax moves around and gets his left cheek in the way.

The operation of the cyclic friction on my machine is delightfully linear - I just wind it up a little more as the ride gets rougher.

I dont experience breakout force at all, irrespective of the setting.

A smoother ride guaranteed with the friction applied.

Thanks a lot for such informative posts. Newbies like me need this type of feedback. Flying a heli after 31 years of fixed wing really focuses the mind!

All the best

Hairyplane
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Old 15th Jun 2007, 16:09
  #912 (permalink)  
 
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How do Hairy Plane

I know its late in the day to add my 2 penneth to this thread but...

I made the mistake of touching the collective friction on my line check and the examiner went ballistic! ney F*$kin Berzzzzurk!

I only touched it as a " touch it so he can see your checking it..."!

ive only got a couple of hundred hours on R44 Raven 2, so will happily bow to the experienced pilots that do this for a living.

Regards
Skysmurf
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Old 15th Jun 2007, 19:26
  #913 (permalink)  
 
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Hairy surely you mean his right cheek unless he's facing backwards
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Old 15th Jun 2007, 20:22
  #914 (permalink)  
 
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Nah, he means his left cheek with the collective left in........
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Old 15th Jun 2007, 20:23
  #915 (permalink)  
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PIC sits in the right seat on Helos bvgs, so hairy is spot on. It would be lardy lads left assslab thats shoving the lever down.

Edited to say we've all left the dual controls in before by accident. I know I have And yes, its nearly bit ME on my harse before
 
Old 17th Jun 2007, 11:35
  #916 (permalink)  
 
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I fly an R44 II so I know this, I just didn't think a low time heli pilot would allow a passenger anywhere near duals. They should be removed. With regard to cyclic friction, this device was NEVER intended for this purpose. Whether it works or not I think is irrelivant, it was only ever designed to lock the cyclic when the heli is on the ground as per Pilots Handbook.

My advice to you Hairy is to master the heli as you were taught, when you have several and I mean several hundred hours under your belt you may wish to experiment. Personally I wouldn't, I think Frank Robinson and his team know their machines better than anybody and what they say goes IMHO.

Safe flying.
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Old 17th Jun 2007, 11:57
  #917 (permalink)  
 
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As far as cyclic friction 'in flight' goes in the first instance, refer to the Flight Manual. Secondly if holding the cyclic of a hydraulic powered machine is so tiring then maybe some gym time would elevate the problem. And it aint no aeroplane. I fly 4-6 hours every day in a hydraulic boosted machine with legs up 3hrs if a get bored I sometimes swap hands or fly with my knees. I would never resort to applying friction to the cyclic in flight in the event of the unexpected, or an emergency, I little collective friction applied is different as in does not require the control finesse the cyclic does.
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Old 17th Jun 2007, 12:30
  #918 (permalink)  
 
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Totally agree with rotors88.

Cyclic friction was not designed for use in flight no matter how lightly applied, it personally freaks me out if anything is working against the freedom of the controls.
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Old 17th Jun 2007, 14:26
  #919 (permalink)  
 
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Does the Hydraulic R44 have cyclic trim like the Astro's?

If so, then keep in mind if you have a trim runaway, it will take you a lot longer to notice it and respond and accordingly isolate the relevant trims, possibly letting the trim to get to full deflection.

I agree with the previous posters, cyclic friction should not be used in flight.
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Old 17th Jun 2007, 15:26
  #920 (permalink)  
 
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Hi all,
I have about 900 hrs R22, 5000 hrs R44 (Astro, Clipper I, Raven I, Raven II, Clipper II). Training, Pilot checks, maintenance, tunaboat, external load, name it....

a) Astro - I don't use the friction there, but will switch off trim in turbulence.
Find a moment where the cylcic is not hunting in turbulence, switch off the trim and you have a neutral point that holds. If you forget to switch the trim back on, you will find out on approach .

b) Hydraulics:
Depends - whether the machine is new or "run in":
At some point Robinson used rather tight rodends, that would need some 300 to 600 hours to loosen up. It was rather stiff, no friction needed. In a hover it was impossible to have a soft touch. I would have to apply a good grip to make the brake-out bump transparent. You could let go of the cyclic and it would not move at all.
Robinson changed the rodends on newer ships and they are rather nice now.
There is no or very little brake-out now, but a rather smooth drag on the controls. In a new helo you still can let go of the cyclic and it holds.
In well used hydraulic ships the rodends are loose (but no play, please!) and the cyclic becomes sensitive without a little friction - LITTLE friction, just enough to introduce a little drag, there is no brake-out force, as this came from the new rodends not the hydraulics. I am only refering to the rodends BEFORE the hydraulic cylinders.
No friction means the cyclic will fall wherever its own weight will push it if you let go of the cyclic...
As mentioned before, when the air gets rough a light helo like the Robinson will cause some pilot induced turbulence, allthough it is not half as bad as a EC120 or AS350.
Eurocopter instructors will insist to apply enough friction to keep the cyclic from moving in case it slips your hand. Personally I adjust it depending on weather, intended use, mood, what foot I got on the floor first that morning, whatever...

Gentleman, remember, for every pilot out there there will be a different set of rules, settings, preferences to apply.
Try it out and use it as you like, it also depends on the machine.
Those who insist, that friction is "dangerous", it is only dangerous if you lock it! In some occasions it may even prevent you from a spontaneous (panic) move - liek avoiding a bird you didn't see inthe first place...
No trim in the hydraulic ships!


Same for the collective in the Robinson.
Friction should be adjusted in a manner, that full friction application still lets you lower and raise it - never fully locked!! If you need more friction than that, put it in the shop!!
Also on the hydraulic collective, there should be NEVER a climbing collective!
(Actually in the electric trim one either....)
A decending ("heavy") collective should be only very little, basically induced only by its own weight (collective lever) with all the friction off.
If it is really heavy, into the shop!
It is may be some tedious work on the electric trim helo to get the collective right, but this is a "good" indication of bad rigging if the collective is excessivly heavy.

Hope it helps!
3top

Last edited by 3top; 17th Jun 2007 at 15:38.
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