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HomeAircraftHelicopterHenseleit 3DNT - Rocket - 3DMP › 3dmp head wobble?
04-04-2005 12:20 AM  13 years agoPost 1
Ronan

rrNovice

Galway, Ireland

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I have been experiencing this issue for a while now and can't seem to figure it out. The heli seems to get into a strange wobble at a lot of different RPM's. It starts out fine and then a resonance builds up and the rotor head seems to shake. This machine has never been crashed and I am using the recommended NHP razor blades.

Any suggestions would be appreciated. Has anyone else experienced similar issues with their MP?

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04-04-2005 08:22 AM  13 years agoPost 2
Reesy

rrKey Veteran

In the doghouse ... Nottingham UK

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Hi Ronan
Yep, bad
First off re-read the manual especially P57 most of it seems to come if the blades are too tight, mine now are a gnat's between too loose (fold back on spool up, not good) and too tight, it's the finest margin the tiniest bit tighter and the wobbles start.

Also try a different HS as there's frequency issues.

You'll prob need to sand the blades to get the right fit.

Paul

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04-23-2005 06:01 PM  13 years agoPost 3
DangerousDick

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Cheshire, England

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Had a 'closer' look at my head today after a few flights - all of which went swimmingly except the wobble returned on the last flight of the day (I know it's a bad idea, but I still have that 'one last flight ).

Noticed there is some play laterally on the feathering shaft so I introduced some alternative shims between the grips and the white 'inners'. These were Robbe bits I had on the shelf S1585 8x13x0.5mm.

I didn't put them on in addition to the ones already there as they are quite a bit thicker and when I tightened the bolts up it took all the play out but still allowed movement (didn't feel too tight).

I'll be trying it out tomorrow and will take the originals just in case I've made it worse but if it gets better I may try adding them aswell to see if it clears up completely.

Cheers
Richard.

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04-24-2005 09:59 PM  13 years agoPost 4
DangerousDick

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Cheshire, England

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1st, second, and third flights today and I would've said I'd sort my particular 'wobble' out but on the fourth we decided to 'up' the headspeed a little and as soon as the throttle was adjusted (on the Tx) the wobbles returned.

Blades are being checked tomorrow to make sure they're 'matched' OK.

Cheers
Richard.

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04-25-2005 08:04 PM  13 years agoPost 5
Ronan

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Galway, Ireland

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I think I have tracked down the source of my head wobble. I tried a different set of blades yesterday (SAB's) and there was little to no wobble. The only sign of head wobble was after switching into idle up but that went away after a second or two.

I will have to put the NHP's on a balancer and see what the story is.

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04-25-2005 10:05 PM  13 years agoPost 6
iachia

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Milan, Italy

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I knew I should have stayed with my beloved SAB blades instead of buying those NHP...
Does the SABs fit the blade holders right or do you have to sand them like with the NHPs?

_____________
Synergy N9

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06-10-2005 02:24 PM  13 years agoPost 7
FR0D0

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Auckland, New Zealand

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Nobody answered. Guess its too late now?

Anwyay, I am using the SAB blades, I also have the NHP's

The SAB need the 4 - 3 mm collar and one spacer on each side to fit in the blade holders. That makes them too tight a fit, so I sanded down the metal spacer from 1.05 mm to 0.96mm, I have the blisters on my fingers to prove it :-)

Anyway, now they fit perfect and dont have the wobbles every one else noticed.

Another thing I dont know what all the fuss is about having them tight enough not to bend on startup, the blades are supposed to be loose enough to turn in the blade grips easily without too much force, so obviously it will move in the grips on startup.

Mine move on startup too, but in a few seconds they are perfectly straight due to the centrifugal force.

In my opinion blades can only be too tight and not really too loose.

But what do I know?

I only hovered my MP for the first time today for 20 Minutes,
LOL

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06-10-2005 07:00 PM  13 years agoPost 8
rcman

rrKey Veteran

Logan, Utah

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To loose of blade can cause a boom strike on a bad auto or if you really suck and collective managment and bog the blades down in a Maneuver
David

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06-13-2005 02:04 PM  13 years agoPost 9
iachia

rrVeteran

Milan, Italy

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I switched to SAB blades too and noticed that if you use the spacers that come with them they fit too tight.
I then installed the plastic spacers from NHPs and the fit is perfect.
I still get a little wabble from 1750 to 1850 rpm but I fly at 1950 and at that speed the head is just perfect.
The SABs are much better overall IMO: more lift and more aggressive.

_____________
Synergy N9

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06-13-2005 02:09 PM  13 years agoPost 10
FR0D0

rrNovice

Auckland, New Zealand

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Hey iachia do you think those SAB's will be better than the NHP's for a beginner such as myself?

I have the NHP's but havnt tried them the SAB's just looked nicer.

Let me know,

Cheers

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06-13-2005 02:25 PM  13 years agoPost 11
iachia

rrVeteran

Milan, Italy

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I think both will do the job just fine for a beginner.
Just get what is locally available so if you need a replacement you don'thave to wait for the shipping.
I prefer the SABs mysel but that' also because I've beenflying them for a long time on all my helis.
I also agree the SABs look better

_____________
Synergy N9

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