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Apraxin · 01-07-2014, 01:29 PM

Hi all!
For a few months I can`t solve shaking issue on Vraio Acrobat. After takeoff the heli starts fast shaking. Firstly i think that it is wrong rigid gain settings. I have change between 0% and 110% is no result. Main rotor speed 1150rpm, helicommand 3sx with ultrasonic hood.

yf222000 · 01-07-2014, 10:39 PM

Hi. It's just a wild guess from me, but by chance you checked and balanced all blades with overall weight wise and length wise? It's hard to tell from the vid, but it looks like mechanical induced vibrations and not by HC3. I'm running HC3-SX on my turbine also, and at high gain on my bird before, the shakes was a little slower than your heli does. Hope you can find the cause for it quickly.

cbergen · 01-08-2014, 08:11 AM

As a test, take off the taller landing gear, put the stock gear back on.

See if the "Shake" disappears...

Scott54 · 01-08-2014, 09:30 PM

I'm with Chris, looks like landing gear resonance, it will probably go away with shorter gear.

Coop

DenisFerrari · 01-11-2014, 05:21 AM

+1
I think it could be big landing gear induced oscillation / low freq resonance too

helibeli · 01-12-2014, 12:03 PM

I think if you did have landing gear resonance it would manifest itself on the ground before take off and I had to immediately shut down the engine every time.I had this with my Predator turbine,i made a homemade undercarriage and it disappeared.The only way to find out is to try a change of undercarriage.Looks like you have a minor imbalance in the head there.

Apraxin · 01-12-2014, 05:49 PM

Hi guys!

Thank you all for your good advice. Ordered stock landings.

The previous owner said that the helicopter had no such problems. But front struts were set slightly shorter (standing on the ground the helicopter was tilted forward by about 5-6 degrees). I leveled them horizontally before flying . Maybe try to return the angle of 5-6 degrees.? still waiting for stock

01-07-2014, 10:39 PM	#2 (permalink)
yf222000 Registered Users Join Date: May 2012	Hi. It's just a wild guess from me, but by chance you checked and balanced all blades with overall weight wise and length wise? It's hard to tell from the vid, but it looks like mechanical induced vibrations and not by HC3. I'm running HC3-SX on my turbine also, and at high gain on my bird before, the shakes was a little slower than your heli does. Hope you can find the cause for it quickly. __________________ One left side Align 450 frame. 1 red cable from 35Amps ESC. Half landing skid. 2 servo horns. 3 ball links.

01-08-2014, 08:11 AM	#3 (permalink)
cbergen Registered Users My HF Map location Join Date: Apr 2004	As a test, take off the taller landing gear, put the stock gear back on. See if the "Shake" disappears... __________________ Chris D. Bergen Bergen R/C Helicopters

01-08-2014, 09:30 PM	#4 (permalink)
Scott54 Registered Users Join Date: Apr 2013	I'm with Chris, looks like landing gear resonance, it will probably go away with shorter gear. Coop __________________ Runway?...We don't need no stinkin runways..... Runways are for models, Wings are for fairies...

01-11-2014, 05:21 AM	#5 (permalink)
DenisFerrari Registered Users Join Date: Dec 2006	+1 I think it could be big landing gear induced oscillation / low freq resonance too __________________ T-Rex100,T-Rex150,T-Rex250 Hughes500E,T-Rex250 SE, T-Rex450,T-Rex450 AgustaA109,T-Rex450 Hughes 500E, T-Rex450 Ecureuil,T-Rex500 EC135, T-Rex600E A-Star Ecureuil,T-Rex600E PRO,T-Rex 700N,T-Rex 700E F3C,T-Rex 700E A109 Power,Raptor 90 3D,T-Rex 744 JET

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01-12-2014, 12:03 PM	#6 (permalink)
helibeli Registered Users Join Date: Aug 2008	I think if you did have landing gear resonance it would manifest itself on the ground before take off and I had to immediately shut down the engine every time.I had this with my Predator turbine,i made a homemade undercarriage and it disappeared.The only way to find out is to try a change of undercarriage.Looks like you have a minor imbalance in the head there.

01-12-2014, 05:49 PM	#7 (permalink)
Apraxin Registered Users Thread Starter Join Date: Jan 2012	Hi guys! Thank you all for your good advice. Ordered stock landings. The previous owner said that the helicopter had no such problems. But front struts were set slightly shorter (standing on the ground the helicopter was tilted forward by about 5-6 degrees). I leveled them horizontally before flying . Maybe try to return the angle of 5-6 degrees.? still waiting for stock

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