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HomeAircraftHelicopterAlignT-REX 700N › Tree 700N DFC shakes/vibrates when inverted
08-30-2013 09:38 PM  5 years agoPost 1
meatbomber

rrApprentice

Klatovy, Czech Republic

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He'll guys maybe one of you has an idea... I've got a 700N with DFC head and its vibrating or rather fluttering but only when inverted.

I'm running MS Composite Rapid Flybarless 690s and an Align 91HZ with Hatori 939 head speed 1950rpm. servos Savox 1258 TG and BeastX. I had a crash a while back but had everthying replaced what was broken. Then I was chasing engine troubles after a broken clutch, now the engine, clutch and start shaft as well was exhaust and fuel system are checked /repaired and restored as necessary, engine is working great, the only gripe I have is strange noise/shake when inverted

What I Allready did:
Changed Blades - no charge
Changed main shaft - no change
Changed head dampeners (Pom) - no change
Changed feathering shaft - no change
Replaced all plastic eyes all around - slight improvement no more slop from servo to grips
Removed / relubed and checked all bearings in the head - no change
Checked DFC pitch link attachment screws for straightness - ok
Checked up down play of main shaft - no up down play
Changed main gear and pinion to new slant gear - no change
Checked tail shaft and all tail drive gears - all ok
Checked all balls for tightness - all ok
Now I'm out of ideas..

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08-30-2013 10:23 PM  5 years agoPost 2
wrongler

rrProfessor

Brewerton, New York

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Check the main blade mounting bolts, make sure they are not bent, and make sure the main blades are NOT too tight.

Bill Whittaker

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09-01-2013 07:37 PM  5 years agoPost 3
meatbomber

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Klatovy, Czech Republic

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Did both and both where ok.. any other ideas?

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09-01-2013 11:50 PM  5 years agoPost 4
MattUK

rrApprentice

Lancaster, UK

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Does the blade tracking change at all when inverted?

Matt.

----
Light travels faster than sound. That's why some people appear bright until they speak.

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09-02-2013 12:48 AM  5 years agoPost 5
wrongler

rrProfessor

Brewerton, New York

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Maybe the dampers in the head?

Bill Whittaker

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09-02-2013 03:00 AM  5 years agoPost 6
meatbomber

rrApprentice

Klatovy, Czech Republic

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Slightly, you can see the whole heli wobble and the beast reacting to it too so there is a lot of movement in the swash abd thus in the blade tips too. Upright tracking is perfect tho..
Oh well I'll have tge next 2 weeks to ponder the problem as I am on a business trip.

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09-02-2013 03:08 AM  5 years agoPost 7
Zaneman007

rrElite Veteran

Texas - USA

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Bearings?
I'm just talking out loud here, but you might want to grab the heli by the blade grips, turn it up side down and rotate it to see if anything is notchy or grabbing.

Old Guys Rule!

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09-06-2013 12:39 PM  5 years agoPost 8
rpat

rrElite Veteran

Weirton, W. Va.

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Have you tried a different set of blades on it?

OK that is the first thing on the list. My bad!

trex 700fbl cal30,minititan,, trx600fbl,trex250,logo 500,Velocity N2

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01-06-2014 10:14 AM  4 years agoPost 9
meatbomber

rrApprentice

Klatovy, Czech Republic

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I got ridd of teh shake / wobble after replacing all the linkage eyes in the head and the bellcrank system. apparently there was too much slop that was taken up when upright but not when inverted.

A new thing has crept up however and thats a strange pretty loud intermittent clicking noise. it´s only sometimes a single click/tock usually during hard pitch changes.. teh only thing i hear when shaking teh heli hard is teh clunk line weight and i check pretty much everything else, may it be possible to hear teh clunk smaking the tank during flight?

Except for teh noise teh heli is flying and behaving like a champ and that engine which has 200+ flights on it now is starting each and every time after the first sec or so of starter, man i love those OS91s

cheers
MB

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01-14-2014 07:28 PM  4 years agoPost 10
Puffy929

rrApprentice

N W Ohio

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The clicking is the main gear and tail output gear slipping. If you continue to fly this way, you will lose your tail. Ask me how I know. Took me forever to find it. I was inverted at about 20 feet when the tail let go. Replace the tail gear and the main gear and the clicking will go away.

TRex600Nitro YS 50 JR9303Converted to 2.4 TJ Pro

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01-15-2014 07:22 AM  4 years agoPost 11
meatbomber

rrApprentice

Klatovy, Czech Republic

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Yesterday a friend of mine and my girlfriend had the tail out on my 700N (great to have a girlfriend that also flies ) while i was on a business trip.

They found that both TT bearings came loose and moved all the way out along the torque tube!

So basically the wobble must have come from the torque tube bowing while under load.

i`m wondering if that might have been the clicking too when the torque tube twists and bows under large torque changes in the tail and hits the inside of the boom.

Puffy - where did you have that slippage? you mean the straight gear on the intermediate shaft on which also the front umbrella gear sits ?

cheers
MB

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01-16-2014 09:51 AM  4 years agoPost 12
meatbomber

rrApprentice

Klatovy, Czech Republic

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been reading up on some of the older issues, and guess what lots of people had issues then with skipping teeth on the tail drive.

i`ve inspected the mesh and there is a lot of slop. so have a new 700N auto gear and front Torque Tube drive with the slant gears on the way, if that doesn´t mesh properly i`ll ditch the original fasteners for standard hex head screw, slot the frame until i can get proper gear mesh.

MB

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01-18-2014 03:54 PM  4 years agoPost 13
meatbomber

rrApprentice

Klatovy, Czech Republic

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All problems solved

Clicking noise definitely was mesh of the autorotation gear and the torque tube drive, now with the new gear set with the slant teeth, no ore clicking.

Wobble and funky tail noise was definitely loose tail support rod ends I pulled them off revalued and re-pinned them 90degrees from the original pin hole.

Inverted wobble was loose DFC dampeners and plastic link eyes in the whole servo to blade circuit.

Now it's like a new heli

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