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HomeAircraftHelicopterHelicopter Main Discussion › flybarred heli and bad shakes
11-14-2014 04:18 PM  3 years agoPost 21
Aaron29

rrProfessor

USA

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There's nothing wrong with it, it's just how the 700N flybar model is.
The old V2 Raptors had a little quirk. They'd often ground resonate dance on hard surfaces when spooling up or down. Scary and it seemed it wanted to topple over. Raptor owners learned to just punch throttle through it. Was better taking off from soft surfaces. And once airborne you had a blast.

Just a quirk. Was otherwise a great heli. Perhaps I'm spoiled with quirkless helis now.
Just crank up the headspeed until it goes away and it'll be fine
Well that saves the OP some time, I guess.

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11-14-2014 05:25 PM  3 years agoPost 22
goof2

rrApprentice

Bristol,CT

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Like mention before
bent axle or main shaft.. blades to tight for HS.. worn swash or links.. run HS between 1850 to 1950.. check all head bearings are good and installed properly.. New dampeners but harder dampeners will shake more at low HS..

I would flip the grips but that is another topic.

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11-14-2014 08:52 PM  3 years agoPost 23
unclejane

rrElite Veteran

santa fe, NM, USA

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The old V2 Raptors had a little quirk. They'd often ground resonate dance on hard surfaces when spooling up or down. Scary and it seemed it wanted to topple over. Raptor owners learned to just punch throttle through it. Was better taking off from soft surfaces. And once airborne you had a blast.
Just a quirk. Was otherwise a great heli. Perhaps I'm spoiled with quirkless helis now.
The 700N will do that too, but you have to bonk the landing juuust right to get it into a ground resonance.

One of mine got into that skid-stamping thing once or twice and it was violent enough that I thought it was going to break something. But it's a tough machine and it survived both times.

I was too surprised at the time to take back off, so I just did the deer-in-headlights thing until it finally stopped.

I've had my trex 800 do it very mildly in soft sand once, it dug quite a ways down into the dirt and the tail skid just barely kept the TR blades from hitting the ground.

I think the 700N is a little more susceptible to this due to the low CG, but most helis can still do this if the conditions are just exactly right.

LS

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11-14-2014 10:03 PM  3 years agoPost 24
ticedoff8

rrKey Veteran

Morgan Hill, CA. USA

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If Honda411 is still reading:

The shaking you describe is coming from the main rotor assembly.
This includes everything from the main gear up to the top of the head.

Looking at the main mast - is it bent? The easiest way to tell is to remove it and roll it on a flat table top or piece of glass. If you see a gap, it is bent. Get a new one.

Check the main gear and the OWB main gear mounting hub. Are they located correctly and screwed down tight? If the hub is not true, the main gear will wobble and look like it is out of round.

Could be bearings - but I doubt it.

I would check the main blade tracking in hover.

Check the feathering shaft.
A quick and easy way to check the feathering shaft is to use a hex driver and turn one side's main grip bolt clockwise and observer the other side's main grip tip. If the other side's main grip tip is moving while you are turning the hex driver, the feathering shaft is bent.
Or, pull it out and roll it on a flat table.

I would then check the balance and alignment of the flybar.
* Remove the paddles and using a ruler, carefully measure from the headblock to both of the tips of the threaded flybar. Make sure they match so close you cannot see a difference on the ruler. Then lock down the flybar.
* Check the flybar control arms - they should be at 0-degree with the swash level.
* Then screw on the paddles and measure to the outer tip of the paddles. You should be less than 0.5mm off from side to side.
* Check the tracking of the paddles. With the swash level (as checked with a swash leveling tool) the paddles should be at 0 degrees. No matter the collective, just make sure the cyclic is level and the paddles are level.
* It might be worthwhile to weigh the paddles. There is quite a selection of paddles. Lighter paddles are for faster reaction (3D) and heavier paddles are for stability. You may accidentally have a mix - one heavier than the other.
* If you have flybar weights - remove them and throw them in the garbage.

If all else looks good, and you find that the shaking goes away at a higher headspeed, then I would replace the dampers.

I flew that head between 1600 (idle up 1) and 2000 (idle up 3) RPM with out any issues.
I still have one on the shelf.

While not the same "Work of industrial art" that the Raptor 90 3D all metal head was, it is still a nice unit.

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

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11-14-2014 10:12 PM  3 years agoPost 25
revmix

rrKey Veteran

NJ

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this seems to be mast bumping.
does not happen in rigid head or fully articulated rotor system, only can occur with the teetering [seesaw] rotor design

to check the shake; run it up without the main blades [& tail blades removed]
unbalanced mains/too loose in the grips &/or spindle out of center in the head

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11-15-2014 03:41 AM  3 years agoPost 26
foolforspeed

rrNovice

San Antonio, Texas

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The first thing I would check is blade tracking. If the blades aren't tracking it will shake rattle and roll. Put 2a different color strip of tape towards the end of both blades and hover it where the blades are at eyeball height. If you see 1 color on top of another then they are out of track.

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11-15-2014 06:41 AM  3 years agoPost 27
artimus

rrKey Veteran

Buckley WA

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have you checked the motor to see if it is not rich.....a rich motor will make a heli shake like a dog crapping out peach pits.....

Fly Hard......Team Viagra

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11-15-2014 07:55 AM  3 years agoPost 28
honda411

rrKey Veteran

Surprise, AZ USA

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Thanks for all of the replies! Tons of reading!
Okay so i pulled the head off and balanced it on a balancing thing for props. The main shaft and spindle were perfectly straight when i rolled them. The head actually came out balanced perfectly. Paddles were right in position. I slapped a new set of blades on and a tad looser in the grips. Seemed to work pretty good!

HeliDirect Field Rep, Synergy N7 w/ OS 105, Torq Servos, Cyclone/ Rail blades

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11-15-2014 12:44 PM  3 years agoPost 29
revmix

rrKey Veteran

NJ

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The first thing I would check is blade tracking
how is it possible if cannot even run it up due to too much vibration/shaking
chicken dance; unbalanced main blades are always the culprit

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11-30-2014 07:08 PM  3 years agoPost 30
honda411

rrKey Veteran

Surprise, AZ USA

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I got everything all sorted out. The thing flies like a champ now! Thanks to all of you who helped me out!
I tell ya, the setup sucks, but the way it feels while flying is awesome! Unfortunately im selling everything I have now. Time to go back to school and fund that project

HeliDirect Field Rep, Synergy N7 w/ OS 105, Torq Servos, Cyclone/ Rail blades

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11-30-2014 07:27 PM  3 years agoPost 31
Stephen Born

rrElite Veteran

USA

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...

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11-30-2014 10:19 PM  3 years agoPost 32
shingalingding

rrNovice

rayne Lousiana

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yea man what was the end result? in suspense?

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11-30-2014 10:21 PM  3 years agoPost 33
revmix

rrKey Veteran

NJ

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slapped a new set of blades on
see above, usual suspect when bouncing shake

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HomeAircraftHelicopterHelicopter Main Discussion › flybarred heli and bad shakes
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