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HomeAircraftHelicopterThunder TigerOther › Blades going out of track during 3D manouvers
10-12-2005 05:36 AM  12 years agoPost 21
Alan Szabo Sr

rrKey Veteran

Las Vegas, Nevada

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Please keep us informed, for I would like to get to the bottom of this also.

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10-12-2005 06:02 AM  12 years agoPost 22
Santiago P

rrProfessor

South West, Ohio

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I would say that play in the collective servo could have most likely caused that ever so unwanted 'flutter'
My friend merlin3 just went through the same identical problem. His R50 will flutter almost every time it turned above 1950rpm. After inspecting the controls almost a dozen times, the only thing we could find was a large amount of play on the collective servo.
Unfortunally, his raptor50 crashed recently of what we assumed to be a collective servo failure in the form of striped gear. Probably all the darn flutter that it when through cause fatigue and the eventual failure.

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10-12-2005 07:26 AM  12 years agoPost 23
Micro-Maniac

rrElite Veteran

Pasco,Washington Formerly: Captain Chaos

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There you go. I'd say the sloppy servos are just a symptom of the real problem. Flutter wearing the servo which then amplifies the problem? Maybe you don't really notice the problem until it wears a servo which gives it slop to really resonate with and make you take notice. Fresh servo could just be taming it again for awhile? My far out theory anyway.

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10-12-2005 12:42 PM  12 years agoPost 24
lavarocks

rrApprentice

Rochester, NY

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It's not too "far out" of a theory, mine was good for awhile after switching to an 8311 from an 811, but now it has come back.. Once again, only above 1950 RPM or so. I will try moving the link in on the servo and using endpoints to get my collective range I think, as this masked the problem for dozens of flights with the 811 before I swapped it out.

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10-13-2005 07:31 PM  12 years agoPost 25
nitroholic

rrNovice

Warren, Michigan, USA

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I experienced blade flutter with my R50 V2 after a crash and rebuild. Flutter occurred each time near zero pitch. Tried a number of checks and possible fixes. Narrowed it down to using a none TT spindle (generic brand) and over 1950 head speed. In testing I found the generic brand spindle to be very soft! During the process I took out 2 JR 8311 gear sets. Lost collective each time - brought it down with positive pitch (fixed) really lucky to save it twice!

John

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10-14-2005 06:33 AM  12 years agoPost 26
Cherokeepilot

rrNovice

Charlotte NC

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Well here are my results:

I previously changed out dampeners thinking that was the problem. No.

I also own a Raptor 30V2 which runs beautifully. Thinking bearings and thrust bearings could be the culprit, I took the blade grips with all bearings and thrust brgs from the 30 and I bolted the grips to my problem Raptor 50.

This morning I drove to the flying field for a test flight. Fired it up, lifted off and stabilized hover low to the ground and then almost full power upwards to see what would happen. Within 2 seconds, woof woof woof and shake, could barely get it back to the ground.

Next step drive across the street to the hobby shop. Convenient!!! Decided to try a new digital collective servo. $60 later, back to the flying field. I light it off and same darn out of track condition!!! RPM was tached around 1850.

I am at a loss. Have no idea what else could cause this problem? I have not tried different blades yet, but I do not see that causing the problem. That will be the next test!

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10-14-2005 11:24 AM  12 years agoPost 27
Cicolli

rrApprentice

Perth, Western Australia

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Hi All,

Just wondering if anyone has tried changing the main rotor hub pin to see if it makes a difference. I too have blade flutter problems with my rappy 50 that just wont seem to go away.
I have replaced just about everything with no luck. The other day I noticed that the hub pin looked a little worn and was a very loose fit over the spindle. Just waiting for a replacement to give it a go.

Paul.

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10-15-2005 02:43 AM  12 years agoPost 28
Cherokeepilot

rrNovice

Charlotte NC

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Cicolli

Give a different hub pin a shot. I dont think that could be the problem though. I looked at mine and it looked identical to an extra one I have in my toolbox. I may try it too just to see before I rule that part out totally.

At this point I have ruled out a possible bad collective servo, bad bearings, bladegrips, or thrust bearings. I took those parts off my Raptor 30 which flies wonderfully and bolted them onto my 50 and ended up with an out of track condition again.

There has to be a specific part or parts in these 50s that are not holding up to a 50size engine. The point is, if you were to take your 50 head off and bolt it to a Raptor 30 with a 30 engine, I bet it would not flutter!

So if the parts are interchangeable between a 30 and 50, do you think the parts really need to be larger and stronger for the 50 size version? I do realize some of you out there are having perfect success with the stock 50 Raptor. I wish I was!

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10-16-2005 05:18 AM  12 years agoPost 29
Santiago P

rrProfessor

South West, Ohio

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What blades are you running?
The natural harmonic you are hitting will always begins in the place were it ends, the blades.
Some combination of dampeners, blade stiffness and linkage play may all add up at a given point, and bingo, you have flutter. The particular "high RPM" is were everything meets. There may be nothing broken, loose or less than perfect on the heli, and it will flutter everytime all these harmonics line up. It IS JUST NATURE TAKING ITS COURSE! Full size helicopters have all kinds of harmonic resonance problems even though engineers take every and care to design around those, and operate around them. It is very hard to avoid these conditions all the time, since they are too many combinations that will cause them.

The way I see it you have two choises, completely avoid the RPM range were the harmonics occur, or, change something major, like the blades.

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10-16-2005 05:57 AM  12 years agoPost 30
lavarocks

rrApprentice

Rochester, NY

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That's a good point. What blades are everyone running that is having this problem?

I'm running the TT 600 Carbons..

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10-16-2005 07:58 PM  12 years agoPost 31
SPB

rrElite Veteran

Athens - Greece

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Update No2
Hi everyone again.

Here is a small update on my initial problem that maybe will help Cherokeepilot and everybody else here.

As I said in my last post after changing the thrust bearings and the blade grips with no success I changed the dampeners and the problem seemed to be solved BUT a couple of flights later and after some consequitive stationary flips here we are again.

I came back here again and checked everything from the start. The collective servo is fine no slope (JR 8301). After a detailed examination on the field with some fellow pilots we found a small up and down play on the main shaft and a slop on the washout arms.

I adjusted the shaft ring and the up & down play gone I also fixed the washout arms slope even if I think it has nothing to do with the tracking problem. Finally I changed the links as Rafael23cc said as they were old enough.

I made three flights doing some hard manouvers and everything so far works OK.


Sotiris
myhelis.com Flying Team

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10-16-2005 08:43 PM  12 years agoPost 32
Cherokeepilot

rrNovice

Charlotte NC

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My main shaft has up and down play as well as a little in the washout assembly. It is the same in my Raptor 30. Believe it is just a common design in Raptors.

Possibly you are not getting as much flutter occurrences because you probably use different blades than I do. I currently have CF Maverick 600s on mine. I did not even balance them either. I will do that this week and try a new set of different brand blades as well this week when I order them. Hopefully the blades are the culprit. Blades are one possibility I have not ruled out yet.

Greg

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10-17-2005 07:08 AM  12 years agoPost 33
Santiago P

rrProfessor

South West, Ohio

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I currently have CF Maverick 600s on mine
WE HAVE A WINNER

Maybe you did not know this, but the Mavrikks are know for being the least forgiving blades when it comes to flutter due to their slightly aft than average chordwise CG. If you have a stiff set up (red dampeners) and a bit of play anywhere in your linkage, the Mavrikks will flutter! (Been there, done that, bought the t-shirt for me an my flying buddies who fly R50s)
My main shaft has up and down play as well...Believe it is just a common design in Raptors
You should be able to eliminate the up & down play completely. If you cant, there is something wrong with shaft collar/ring.

Do yourself a favor and get a different set of blades. If you are into 3D, get some V-Blades, if you can find any. Otherswise, get a set of TTs blades. That will stop the flutter all by it self.

note: I have flown over 6 gallons with Mavrikks at high head speeds (1900+ rpm) with almost no problems. My R50 had zero play or slop in it linkage, but whenever something lossen up, the Mavrikks fluttered.

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10-18-2005 05:46 AM  12 years agoPost 34
Cherokeepilot

rrNovice

Charlotte NC

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MPV,

Thanks for the advice. I am planning on flying again end of this week with new blades and a check of balance. I will post the results.

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10-18-2005 06:19 AM  12 years agoPost 35
Heliscat

rrApprentice

Dublin, CA

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It took forever for you to figure it was the blades! Mavrikks chordwise CG is not the same per blade. How long did it take you guys to ask the question "what blades are you flying?". Buy a set of SAB's and forget your flutter problems. it isn't dampers, it isn't servo play, it isn't swash play and isn't bearing ussues either. I have been through all this. Mavrikk blades are pure junk.

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10-18-2005 07:21 AM  12 years agoPost 36
lavarocks

rrApprentice

Rochester, NY

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TT Carbons are junk too?

I've had the flutter with both sets of mine, and Mavrikks before them!

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10-18-2005 08:20 AM  12 years agoPost 37
flyanything

rrApprentice

Tallahassee, FL

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One thing?
I'm not sure why some here think that the flutter has to be attributed to ONE SINGLE part. Based on the anectdotal evidence presented here it would appear that the problem can result from varying combinations of conditions. For example, a slop-free heli running bad chord-wise CG blades may only woof at 2000 rpm or above, whereas a slop-ridden heli with good blades might woof at 1850 rpm, etc. Bad bearings or a soft spindle may woof on certain blades and not on others. So, changing the blades would appear to solve the problem but it's really just that the new blades can tolerate the bearing/spindle issues without fluttering. But the guy ends up thinking it was all due to the blades when changing the bearings or spindle would have fixed it too.

I've personally seen the woofs fixed in two instances by two totally different means. In one instance it was just too high of a head speed. When the rotor was kept from overspeeding (kept under 2000 rpm), no more flutter, no new parts required. Another time it was a change in blades that fixed it, for whatever reason. I've also heard of others fixing it with new dampers, new plastic head block, etc.

So, it would seem that the best thing one can do is read through these posts and try what others have tried (in cost ascending order) until they find the answer FOR THEIR MACHINE.

John

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10-18-2005 05:00 PM  12 years agoPost 38
turboomni

rrProfessor

East of the Equator

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I don't know if this means anything but I did have woof/flutter on my R30 with TT Carbons. Did have a crash awhile back and replaced bearings main shaft ,spindle ,dampeners. But it flew fine till after the crash repair.
Replaced the blade grips and it was fine. My LHS heli guru said to replace the grips too after a crash since they may stretch abit in the crash and then not hold the bearings solidly anymore.
A random thought.

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10-19-2005 12:10 AM  12 years agoPost 39
Heliscat

rrApprentice

Dublin, CA

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I don't know anybody at my field who flies with a headspeed of 2000. I fly 1650-1750 with both my 50 hyper and YS 91. If youhave a flutter it's usually the blades going out of track at 0 degrees. you must input either a quick positive or negative pitch control to make the flutter go away. I did the "head flip" even after i upgraded to a full metal head (thinking it would correct the problem) and that did make the problem go away. Changing the pitch control from the trailing edge to the leading edge gives more authority. If you notice, helis with the pitch control on the trailing edge of the blades are the only ones that suffer from the woof and maybe poof syndrome.

I have a set of TT 600 carbons but haven't used them. I suppose I could take a balance of them and then fly them. I know I will never fly Mavrikk "the best blades ever".

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11-09-2005 02:18 AM  12 years agoPost 40
Cherokeepilot

rrNovice

Charlotte NC

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Well I have flown another flight on my Raptor 50 which had previous flutter problems a couple weeks ago. I was using Mavrikk blades.

This time I used an $80 set of blades called TG Carbon, made in Germany. I was very impressed. Really flying it hard and no flutter or poof poof poof poof!!! These blades are about a 1/4 inch wider in chord than the Mavrikks and seem to be lighter.

I did happen to carry along a new set of Mavrikk fiberglass blades with me and tried them on the second flight. I was not thrilled over the entire flight, except for the excellent vertical acceleration they had over the TGs. It went out of track 2 or 3 times in less than 10 minutes. I quickly ended the flight to put the German blades back on for a third flight. That flight, they went out of track just once, but very short duration.

I do believe this flutter condition happened everytime regardless of blades used due to overspeeding of the main rotor. Unfortunately did not have anyone to tach while I flew. Perhaps the reason the TG Carbon did not flutter except for once is these blades were much wider in chord than the Mavrikks

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