RunRyder - X-400 is lurching, staggering at low rpm´s

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e-Ark X-400 - MX400 > X-400 is lurching, staggering at low rpm´s

Michy
New Heliman
Location: Germany

Hello to everybody,

I´m a x-400 pilot and I have a question to the experts.
I fly this heli whit the aluminium head tuning parts and with the original wood - blades.
The Heli runs fine without any detectably vibrations.
Bud, when I run the system on a low rotation speed, lower then 2200 rpm the heli start to
lurch..stagger, I hope this will describe the effect.
With a rmp higher than 2300 the effect dissapears.
At high rpm´s I´ve the impression, that the heli is joggling a
fraction of a second after a "hard" movement of the RC Stick.
It this effect well know ?
Can anybody helps me ?

With best regards

Michael

01-14-2008 03:42 PM

copperclad
Elite Veteran
Location: ..

hi Michy

helis will often have vibration at low headspeeds , the blades are probably not slung out straight yet and at higher speeds centrifugal force will straighten them out , if it is running smooth at higher speeds , you should be fine

one thing you can do is check that your blade tension is even , both blades should pivot with the same tension in the blade grips and if the machine is turned on its side the blades should be able to stay straight out , but if you move it down a few centimeters and stop it suddenly , they should swing down , HTH , dana

01-14-2008 04:19 PM

Michy
New Heliman
Location: Germany

Hello dana,
thank you for your commends, bud I´tried everything in
this direction, even when I fly with high rpm´s some minutes and
then slow down the rpm under 2200 the heli began to wobbel , stagger, it´s hard to describe, looks like the heli is drunken.........
When I rises the rpm then, everythink its ok.
When the heli begin tho stagger, its seems the the "amplitude" is rising damatical, so I habe to stop flying asap.
It is not some kind of vibration !

Did nobody else have this effect ?

With best regards

Michaeö

01-15-2008 08:02 AM

whodaguy
Heliman
Location: Saskatoon, SK - Canada

I would check the following:

Even distance on the flybar paddles and they are balanced.
Main blades balanced and tracking
Main shaft is "true" no bend
Tail shaft is "true" no bend
All bearings are free and no hitches

It seems small but the slightest amout of deviance from perfection will affect the stability of these small helis.

Good luck.....

Whodaguy.............................

01-15-2008 12:57 PM

copperclad
Elite Veteran
Location: ..

hi Michaeö

from your description it sounds like TBE , it is hard to describe but the mainshaft starts to move , like a spoon would when you stir a glass of water , and this action gets stronger as time goes on , this makes me wonder if when you are taching it are you reading the paddles too , what i mean is , if you are reading the paddles too , the RPM is 1100 not 2200 , and this is all due to , too low a headspeed , can you say what motor and pinion you are using , i am just taking a shot in the dark and could be way off base , dana

01-15-2008 01:05 PM

Michy
New Heliman
Location: Germany

Hello,

I changed the main blades, main and tail shaft;
flybar paddles are balanced and the distance to the center hub ist
realy good adjusted
I fly the Align TH450 motor, bud I had to check the pinion today
I will post it later on.
The rpm measurement is done at the end of the blades, seems to be OK!
Wath is the meaning of "TBE" "T....

With best regards

Michael

01-15-2008 02:48 PM

copperclad
Elite Veteran
Location: ..

hi Michael

TBE = toilet bowl effect , for the swirling movement , mostly due to low headspeed , it's mostly seen in coaxials , but i had it happen with a Piccolo moth i was working on once

one other thing i thought to try if you can , lower your pitch curve a bit and see if it effects the problem , it would raise the headspeed a bit , HTH , dana

01-15-2008 03:04 PM

Michy
New Heliman
Location: Germany

Hi Dana ,

I fly this heli with fixed rpm´s. Kontronik controller in governour - mode. This controller will be unknown for you, but it works well.
Have anybody experience with the damping of the head ?
Did anybody had changed the o-rings ?

Michael

01-15-2008 03:12 PM

copperclad
Elite Veteran
Location: ..

hi Michael
thanks , yes with a Kontronik controller in governour - mode

i think your idea on the dampeners is a good place to look next , pull the spindle out and check to be sure the dampeners are correct , are they super soft , or worn out , dana

01-15-2008 03:23 PM

hawkkw
Heliman
Location: Salem, Va

Blade Balance

It sounds like the blades aren't balancing out.
I wouldn't get too analytical and start messin'
with mechanics and dampeners until I was darned
sure the blades were right. If you use a store
bought balancer, especially one like Helimax sells,
I'd say there is a 99% chance they're not properly
balanced. Build a simple "cradle" from plywood that
will suspend the blades while bolted together with a
3mm bolt and place a 4ft. level in the back ground.
You may have to shim the level to get it zeroed out,
but it will give you a perfect reference. Assuming
you,ve already picked the lighter blade and found
the cg, just tape away. When the blades even up with
the level in the background your done. I've never
found a balancer that would work as well as this
method. You may get a very slight vibration while
spooling up but thats pretty much normal.

01-17-2008 07:07 PM

Michy
New Heliman
Location: Germany

Hey,

thank for this idea, I´ll have a pair of "Blattschmied" blades,
they are ballanced;I´ll try them on the weekend.
I´ll give you an note!

With best regards

Michael

01-18-2008 12:04 PM

Michy
New Heliman
Location: Germany

Hello ,

bad day .........

I tryed the "blattschmied" - blades today, they are realy good balanced !
I rises the rpm´s and try the hoover the heli; then after some seconds the heli begun to stagger very hard, I was realy afraid that the heli could "explode" !!!!!
I could "land", the heli is OK.

So the effect is worther with the gfk - blades then with the wood blades.

I fly the aluminium head with th plastik blade holders,.., did anybody else fly this configuration ?

I´m a little bit chockedm I think I try a beer........

Michael

01-22-2008 08:20 PM

hawkkw
Heliman
Location: Salem, Va

I'm taking staggering to mean wicked shakes. That sounds
mechanical. I had a mixing (pitch) arm back out one time
and it made the blades pitch differently. I thought it
might explode at the time because it shook so violently.
Check all your arms and linkages and lock-tite the crap
out of all metal to metal fasteners. I found a couple of
screws that were not properly adhesed from the factory.
I also had a servo get the "twitches" once. It was an
intermittent problem but it would start oscilating un-
controlably on it's own. It was mildly noticable at first
and all at once it failed in flight costing me dearly.
Hope you get your gripe narrowed down, patience is the
main thing.

01-23-2008 01:01 AM

Michy
New Heliman
Location: Germany

Hey,

long time no work on this problem, bud now it is solved !!
The Heli was standing as a "dustcollector" but last week I was on a
fair in Dortmund (Germany), on the ACT area I´ve meet a "specialist" of
blade´s .
This man tolt me to "soften" the head, change the O - rings in the head and so on.....
So I change the O-Rings and I turned of 0,2 mm of the plastic spacer witch is located between the O-Ring and the bearings.
And it worked !!!!!
No problems at all!!!!!

Michael

04-30-2008 11:06 AM

copperclad
Elite Veteran
Location: ..

hi Michael

glad to hear you have it sorted out , good work , thank you for updating us with your solution , thanks again , dana

05-01-2008 03:05 PM

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e-Ark X-400 - MX400 > X-400 is lurching, staggering at low rpm´s

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