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Robinson R44

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Robinson R44

Old 14th Nov 2005, 12:58
  #681 (permalink)  
 
Join Date: Nov 2005
Location: australia
Age: 39
Posts: 12
R44 clipper track and balancing

Has anyone experienced their R44 Clipper ( pop out equipped ) go through periods of smooth to buppy flight (vertical bounce) this is the second clipper I have had experienced with and they both seem to change considerably with weight, if the ship is tracked at a certain weight it seems to be way out at the opposite weight. From what others say it seems to be the floats as the only cause. Any thoughts?
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Old 14th Nov 2005, 13:50
  #682 (permalink)  
 
Join Date: Apr 2002
Location: UK
Posts: 593
Most Raven IIs have an 80 kt flutter....it can be tuned out to beyond your speed range on a clipper. Ask your maint people to do a track and balance and shift the vibration up to 120kts. A clipper never sees that speed.
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Old 15th Nov 2005, 10:27
  #683 (permalink)  
WLM
 
Join Date: Mar 2002
Location: 3 Degrees North
Posts: 361
Gaseous
No it has not been re sprayed and from what I can see it is only the top layer of the paint that's bubbling. Yeah I don't think I'll get much joy from Robinson but I'll try.

The 80 Kt fluffer, well we have had this on our Raven I since new, despite numerous track n balance. It gets worse when heavy...

Cheers
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Old 15th Nov 2005, 11:12
  #684 (permalink)  
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Join Date: Apr 2004
Location: Belgium
Age: 64
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Max speed versus Weight R44

A while ago, I stumbled over a weird condition/prediction of my R44-simulator.

When very light (f.ex. little fuel, 1POB), it takes more power to achieve high speeds.

Could be an error, but I can't seem to find it, so I tried to explain it.
I came up with the following possible explanation:

At light weight the trust vector is smaller. To achieve a speed, the drag forces are relatively unsensitive to weight, resulting in essentially the same needed forward force to achieve a speed.
In the case of light weight, and the resulting lower trust vector this requires the rotor disk to be tillted more forward than when heavy. At some point the forward tilt gets so great that it reduces rotor efficiency because transversal flow increases too much, requiring a lot of power to achieve this smaller trust. The rotary wing becomes an inefficient propeller so to speak.

I tried this out on a R44-I and II, and feel that with 2 POB, little fuel it is indeed faster than with 1 POB. Anyone care to comment ?


d3
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Old 15th Nov 2005, 13:48
  #685 (permalink)  
 
Join Date: Dec 2004
Location: UK
Posts: 42
Doesn't Induced Lift and Drag change with weight???

The induced drag curve moves to the right with increase weight and left with reduced weight. Parasite and Profile drag don´t change much in relation to weight. This will effect the Overall Power required curve, this will mean more power is requied for less weight at the same speed.........
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Old 15th Nov 2005, 14:34
  #686 (permalink)  
 
Join Date: Jan 2002
Location: Southern UK
Age: 59
Posts: 282
WLM

What you have described is a Chordwise mass discrepancy on your main rotor.

The twist of the blades as a function of power (blade coning) is controlled by chordwise mounted tip weights (tracking weights) if they are at odds you can only tune the rotor to be good for a narrow AUM range using pitch link and tab corrections.

If you want to cure it you may have to get the blades reweighed and checked for spanwise and especially chordwise CofG , there will be a tolerance on the figures and I suspect you will have two blades on opposite ends of the tolerance. Has one of your blades been repaired I wonder?

Here's a post I did earlier describing how the effect is used to control the track and vibes on a Bell 412

http://www.pprune.org/forums/showthr...19#post1560419


Cheers

W
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Old 16th Nov 2005, 12:53
  #687 (permalink)  
 
Join Date: Jul 2005
Location: australia
Posts: 29
Hooks for r44

Our company is looking at getting rid of our old hooks on our r44's for the latest and greatest on the market.

Any bad stories with with equipment or any recommendations would be much appreciated.

We've heard all the hype about Onboard systems so they must have a good product but outlaying for a few r44's adds up so all feedback adds up

cheers tropic
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Old 18th Nov 2005, 10:12
  #688 (permalink)  
WLM
 
Join Date: Mar 2002
Location: 3 Degrees North
Posts: 361
Wunper: Thanks for the info. I posted 2 days ago but for some reason it is showing up. Anyway will show your info to our engineers

R44Tropic: I asked the same question about 5 weeks ago but did not get any reply may be it is not a popular aircraft type to sling with in the Northern Hemisphere.... Let see what happens this time around

WLM

Oops typo error...meant to say posting did not show up
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Old 18th Nov 2005, 12:20
  #689 (permalink)  
 
Join Date: Jul 2005
Location: australia
Posts: 29
wlm cheers.

mate we have regular sling jobs here. we're actually prefered to our opposition cause they're using jetrangers.

Our clients would rather take a couple of trips slinging gear than using them mainly due to our personel with much smaller ego's

tropic
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Old 19th Nov 2005, 11:04
  #690 (permalink)  
WLM
 
Join Date: Mar 2002
Location: 3 Degrees North
Posts: 361
Gday mate
Now what sort of hook system you're using at the moment? any mirror installation on the R44 or just head out? What can you comfortably lift?
I did my sling endorsement in a B47 then slinged with the Jety but I don't have the big ego..... Been flying a R44 Raven for the last 2 years in the jungle, and need to reposition 44 gallons drums so I thought a hook and 1 drum at a time for short distance would be ok? 2 would be pushing it
Also the NZ company selling the R44 pods seemed to have a hook rep contact, but I'm still waiting
Cheers
WLM
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Old 30th Nov 2005, 14:07
  #691 (permalink)  

Better red than ...
 
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Location: Appleby-in-Westmorland Cumbria England
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R44 Rotor Vibration

The poor CFI got a shock this morning with sudden significant vibration from the rotor head.

The description of the event is:-

Start and airtaxi, nothing out of the ordinary.

Significant vibration starts in the climb, occured intermittent downwind and to land. Continues in air taxi back to the stand.

Vibration felt throughout the aircraft but INTERMITTENT, and tending to occur during pitch changes (hence more during air taxi).

Described as "like flying in high wind condition" but wind was under 5kts.

Examiner who flew it last, describes slight mis tracking on the main blades.

Engineer has a view on potential cause.

Aircraft had annual 7hrs ago. No known defects and nothing obvious (or not obvious) in a visual and 'manual' inspection after the incident. No leaks, cracks in the blade, dents, loose transmission parts, tail rotor still attached.

H-R interested to hear if other people have experienced rotor head vibration in a 44 and the cause.

Discuss

h-r (who has turned blue at the chill of the cost..)

Last edited by helicopter-redeye; 30th Nov 2005 at 17:56.
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Old 30th Nov 2005, 14:11
  #692 (permalink)  
 
Join Date: Nov 2005
Location: ....absolutlely full of it.....
Posts: 35
it's up to you Mr Robinson, the Jesus bolt loves you more than you should know....la la la la.......
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Old 15th Jan 2006, 17:20
  #693 (permalink)  
 
Join Date: May 2005
Location: All over
Posts: 41
R44 Share

Anybody interested in an R44 1/4 share based in Manchester area.

30K plus vat Astro with 1200 hours 5 years to run

If so PM me
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Old 15th Jan 2006, 23:28
  #694 (permalink)  
 
Join Date: Jul 2002
Location: Denver, CO and the GOM
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Re: R44 Rotor Vibration

Originally Posted by helicopter-redeye
The poor CFI got a shock this morning with sudden significant vibration from the rotor head.
The description of the event is:-
Start and airtaxi, nothing out of the ordinary.
Significant vibration starts in the climb, occured intermittent downwind and to land. Continues in air taxi back to the stand.
Vibration felt throughout the aircraft but INTERMITTENT, and tending to occur during pitch changes (hence more during air taxi).
Described as "like flying in high wind condition" but wind was under 5kts.
Examiner who flew it last, describes slight mis tracking on the main blades.
Engineer has a view on potential cause.
Aircraft had annual 7hrs ago. No known defects and nothing obvious (or not obvious) in a visual and 'manual' inspection after the incident. No leaks, cracks in the blade, dents, loose transmission parts, tail rotor still attached.
H-R interested to hear if other people have experienced rotor head vibration in a 44 and the cause.
Discuss
h-r (who has turned blue at the chill of the cost..)
The most common cause in the Robinson for sudden new vibration as you describe is a rotor overspeed.

Last edited by Flingwing207; 16th Jan 2006 at 04:05.
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Old 16th Jan 2006, 02:36
  #695 (permalink)  
 
Join Date: Oct 2002
Location: australia
Posts: 34
Re: R44 Corner

R44 Airconditioning
Can anyone tell me how the Aircond. 44's perform. I wonder if the compressor cuts out under max power, that sort of thing and most importantly dose the air con work good.
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Old 16th Jan 2006, 04:12
  #696 (permalink)  
 
Join Date: Nov 2002
Location: AUS
Posts: 331
Re: R44 Corner

Redeye and 207.

If I was flying any Robinson that developed sudden rotor vibration I would be on the ground FAST. Have a read of the report...http://www.atsb.gov.au/publications/...200302820.aspx
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Old 16th Jan 2006, 05:07
  #697 (permalink)  
 
Join Date: Oct 2002
Location: England
Posts: 242
Re: R44 Corner

Yep, aircon cuts out when max power required. .
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Old 16th Jan 2006, 10:09
  #698 (permalink)  

Better red than ...
 
Join Date: Aug 2004
Location: Appleby-in-Westmorland Cumbria England
Posts: 1,406
Re: R44 Corner

Overpitched.

The person flying was on the ground rather quick.

Was checked by certified engineers (note plural). Head de-ass. Blades off and checked; MR and TR tracked and balanced; hydraulics taken apart.

Nothing found.

May have been some ice build up as it was a cold day and early morning, but like all icematters, now we shall never know ..
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Old 16th Jan 2006, 10:22
  #699 (permalink)  
 
Join Date: Feb 2004
Location: Switzerland
Age: 49
Posts: 175
Re: R44 Corner

HR. I experienced such a vibration in an R44 some time ago. The cause was worn out teeter bearings. The journals that fit into the teflon couted bearings were also damaged since the journals grinded it way into the hub itself Unfortunately I was not flying this particular bird enough to catch the wear early on the bearings. I believe the bearings have since been changed by Robinson because this was a common problem from operators that are pulling lots of torque when slinging. Go to your helicopter and carefully inspect the teeter bolt trust washers. If there is any bearing material missing between the hub and the truet washers your M/R Hub need to have it's bearings changed including the journals....
Good luck
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Old 16th Jan 2006, 10:45
  #700 (permalink)  
 
Join Date: Mar 2002
Location: Midlands
Age: 66
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Re: R44 Corner

Hi Flingwing,

I am an owner/ operator of a new Raven 2.

What damage is done in a rotor overspeed? What sort of cost is involved in putting it right?

Is the R44 designed to withstand the occasional mismanagement of the controls eg not being quick enough on the collective in the auto or mishandling the throttle?

My machine is not used for training or hire but I do expect to let others fly it occasionaly, hence the question. If the risks of accident/ high rectification costs are too great I'l keep it all to myself!

Hairyplane
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