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HomeAircraftHelicopterLow Head Speed Helicopters › Low head-speed wobble - Heavier blades?
02-05-2010 09:30 PM  8 years agoPost 1
"Cam"

rrKey Veteran

UK

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With practicing for my BMFA B Certificate and wanting to fly in a more scale-like way, I have been flying circuits and hovering a lot. With this I have mechanically reduced the throws on my heli and also turned the headspeed down. This suits the flying style and my old batteries.

However, with a lower headspeed of 1850 I am getting a gentle aileron-wobble. It’s not a problem but it is very annoying! It might also give other club members the impression that there’s a problem with the heli!

So I was wondering if fitting blades that are heavier than my Radix Stick-bangers might get rid of this annoying wobble!

I have red infinovation dampers fitted and Red R90 paddles. I don't believe adding flybar weights will help although softer paddles might.

What are your ideas?!

DSX9
EMax V2
http://runryder.com/helicopter/gallery/37491/

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02-05-2010 09:47 PM  8 years agoPost 2
Freya

rrApprentice

Seattle, Washington

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Typically a low head speed wobble will be caused by a balance problem in the blades or the head.

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02-05-2010 09:48 PM  8 years agoPost 3
Heli 770

rrProfessor

USA.

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Try stock dampers with lube and blade bolts maybe too tight for the lower head speed.

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02-05-2010 09:52 PM  8 years agoPost 4
"Cam"

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UK

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The blades have been balanced on a high-point (Quick UK) balancer. The balancers been turned 180 degrees to double-check. Tape was added to the CG of one blade. I've also flown and had the same problem when I took the tape off.

I am wondering if softer dampers will help - only I'd hope someone's already tried this and has the answer before I take my heli to bits!

EDIT - Thanks Heli770! Do you know for sure if softer dampers are better for lower headspeeds? I guess it can't hurt! The blades bolts are the right tightness

DSX9
EMax V2
http://runryder.com/helicopter/gallery/37491/

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02-05-2010 10:13 PM  8 years agoPost 5
Heli 770

rrProfessor

USA.

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My thinking is Infinovation run dry and the feathering shaft is not certering at the lower head speed.

Edit: You use harder dampers for higher head speeds and 3D.

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02-05-2010 10:40 PM  8 years agoPost 6
JAy jordan2

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Cincinnati, OH

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Try softer dampeners first.
It is well known that firm or very stiff dampeners at low headspeeds will cause a wobble.

Also, since you are wanting to fly more scale, regular radix would be more stable than the stick bangers you have on now. Also, heavier paddles would help with stability.
Some of the FAI guys can give more info on this.

JAy

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02-05-2010 10:47 PM  8 years agoPost 7
bowies12

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Surrey - UK

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Also the head is too rigid. Try plastic blade grips.

I upgraded to metal grips a while ago, and removed them soon after because of the wobble. Fine at high head speeds but down around 1600 it wobbled.

Btw 1850 is still quite high.

Fat birds can't fly

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02-05-2010 11:20 PM  8 years agoPost 8
Jeff polisena

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westpalmbeachflorida usa

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This is ERaptor ??

Use soft dampeners also measure all opposing links to same length then adjust tracking with pitch links (grip)
When you have added metal head parts it becomes ridged and the fly bar control loops are the only thing flexing. If you add metal loops you might get rid of wobble but dampeners will probably do the trick cheaper.

I stole it ,flew it and gave it back ;)

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02-05-2010 11:25 PM  8 years agoPost 9
dkshema

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Cedar Rapids, IA

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Typically a low head speed wobble will be caused by a balance problem in the blades or the head.
The same unbalanced blades and head will be silky smooth if you simply goose up the RPM? How does THAT work?

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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02-06-2010 01:05 AM  8 years agoPost 10
djrformcar

rrApprentice

Las Vegas, Nevada USA

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I have the Red Infinovation Dampers on my 600N and 600E, if the head speed drops below 1700rpm they will start to wobble. I use that as a sign that I'm losing too much head speed. The softer dampers do not wobble as soon. Go back to stock soft ones. The red Infinovation ones are really from 3D.

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02-06-2010 06:11 PM  8 years agoPost 11
"Cam"

rrKey Veteran

UK

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I have the red infinovation dampers fitted because I was flying 3D.

The cheapest option seems to be stock dampers - so I'll get some on order!

Plactic grips seem like a good idea! I also have red paddles fitted - might try some black ones if the dampers don't do it.

DSX9
EMax V2
http://runryder.com/helicopter/gallery/37491/

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02-06-2010 11:30 PM  8 years agoPost 12
TheRickster

rrApprentice

Beaumont Texas

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Soften the dampening and it will stop the mast bumping. Common on rigid setup heads...

Rick

If in doubt lean it out . We don't do this to save money, we save money to do this

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02-13-2010 03:01 PM  8 years agoPost 13
Heli 770

rrProfessor

USA.

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"Cam"
Give us an update.

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02-18-2010 08:03 PM  8 years agoPost 14
"Cam"

rrKey Veteran

UK

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Got some (heavier than the Radix) Thunder Tiger carbon/glass blades.
- Shockingly the blades' CGs is further in-board than the Radix!

Went down to an 11T pinion to further reduce the headspeed and get more runtime. (A setup I've run before - has monster torque).

And fitted the blue dampers that are not as squashy as the black dampers I also bought.

No more wobble and I've been getting 12 minute flights of hovering and circuits without the JIVE low-voltage spool-down engaging!

DSX9
EMax V2
http://runryder.com/helicopter/gallery/37491/

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02-18-2010 08:12 PM  8 years agoPost 15
Old Slow Rotor

rrNovice

Elk Grove CA

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So which one of those three things you changed,
You feel fixed the issue?

(the gear change should not have affected the wobble...)

how much further was the inboard cg change?

The reason why I ask is If somebody else reads this they will know what the fix was...

GMP/Schulter/ Graupner Bell 222/HK600GT/X-cell Ct 60/ RCA MD500E

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02-18-2010 09:27 PM  8 years agoPost 16
jschenck

rrProfessor

La Vista, NE.

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Get the blue dampers. Also for hovering around you might want to put the stock black paddles back on.

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02-18-2010 09:29 PM  8 years agoPost 17
jschenck

rrProfessor

La Vista, NE.

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how did you get the R90 paddles on a 50?

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02-18-2010 09:38 PM  8 years agoPost 18
Heli 770

rrProfessor

USA.

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That Heli should be Cam's EMax, it's a 90.

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02-18-2010 11:45 PM  8 years agoPost 19
Yug

rrMaster

UK. Herts

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Every system has a resonance and no matter how perfectly balanced it may seem, the only thing you can do is run the system away from that which promotes the resonance. Given what you are doing, I would drop the HS down to 1650 first, then try using softer dampers. It won't be a 3D monster but it should be nice and smooth.

Vegetable rights and Peace

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02-19-2010 12:38 AM  8 years agoPost 20
jschenck

rrProfessor

La Vista, NE.

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must be the snow, that canopy looks like a 50 canopy! but the frame sure doesn't look TT. I don't know if TT makes the blue dampers for the 60/90 so you might just try the red's in there instead of the infinovation dampers or I think infinovation has O-rings that are softer dampening.

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