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LMH 120 tail problems (not with the casing breaking)

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LMH 120 tail problems (not with the casing breaking)

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Old 10-28-2005, 06:58 PM
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pilot90
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Default LMH 120 tail problems (not with the casing breaking)

Hi guys,
My name is Josh and i'm 14 years old and im fairly new to this hobby but i love it. Anyways, i bought a corona 120 at the biginning of the summer.. thought i would be able to fly it by the end of the summer HA! i finally solved the speed control problems with your guys' advice (i got a brushless setup) but now im having another problem... there is a heck alot of vibration as well as the tail doesnt stay in one place, i decreased the gyro gain and now it doesnt wag but when i lift off the ground it turns about a quarter turn to the right.. E.X. i will start looking at the helicopter directly from behind but when it takes off im looking at the side of it.. any advice would be much appreicated.. thanks.

Josh.
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Old 10-29-2005, 03:38 AM
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Default RE: LMH 120 tail problems (not with the casing breaking)

Hi Josh,
Which gyro are you using? Does the tail continue to turn or just to 90 then stop once you get into a hover? If the model is turning (nose right) only 90 degrees when applying throttle, the gain may be set too low. If you are using a HH gyro and the tail is continuously drifting in the same direction, the problem may be that the TX trims or sub trims are not set to neutral. Or the revo mixing is not at zero. Also be sure the gyro is isolated from vibration by mounting it using foam tape. Vibration in the model along with a low gain will also cause the tail to drift (nose right). In any case you should try to reduce the vibrations. Primary contributors to vibration would be: bent MR shaft, bent stabilizer rod, over tightened ’jesus’ bolt on the rotor head, out of balance main rotor or blade tracking. That’s the short list but it’s where I start looking when vibration comes into my models. Hope this helps.

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Old 10-29-2005, 08:02 AM
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Default RE: LMH 120 tail problems (not with the casing breaking)

hey thanks for your help, im using a pg-03 gyro, i also have a few more questions, what is the jesus bolt? as well as where is the stabilizer rod? one last thing... has anyone else had this problem? the deans antenna was wiggleing arround and it was causing radio interfearence so i unpluged it and it worked much better anyone have any tips about that? thanks
-Josh
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Old 10-30-2005, 05:27 AM
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Default RE: LMH 120 tail problems (not with the casing breaking)

Hi Josh,
Over tightening the bolt (located on the ‘Hub‘) that holds the ‘Main Rotor Blade Assembly’ to the ‘Main Rotor Shaft’ can cause the plastic ‘Hub’ to deform. Because this bolt is slightly off center, the plastic stretches (grows) on one side only. This creates almost the same condition as having a bent main rotor shaft. The stabilizer rod referred to by Lite Machines as the ‘Subrotor Pivot Rod’ is located inside the ‘Subrotor Stabilizer’ (the black paddles above the blades). Most times a crash or even mishandling the model can bend this rod as it is only 5/64” in diameter. I use Deans antennas on my models, I install them exactly as the instructions state. However, it seems people either like them or hate them. I guess I’m fortunate to never have had any problems with them.

One more comment about vibration. Even though I meticulously balance my main blades and rotor head I usually end up with some level of vibration. I cure this by adding a piece of electrical tape to one blade and take it up to hover. If the vibration gets worse, I’ll move the tape to the other blade. If that makes it better, I’ll then try a smaller or larger pieces of tape. I repeat this process until all the vibration is gone. It takes some time to get it right, but it very rewarding to fly a vibration free model. Hope this helps.

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Old 10-30-2005, 08:40 AM
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Default RE: LMH 120 tail problems (not with the casing breaking)

Ill try that, if i over tightend that bolt do i have to by a new piece or do i just loosen it?, thanks

Josh
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Old 10-31-2005, 01:23 AM
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Default RE: LMH 120 tail problems (not with the casing breaking)

Josh,
If the hub is damaged, you will see it bulged out on the side around the bolt. I always just replaced the hub. In fact I used to keep spares on hand. It’s hard to describe, but this bolt needs to be tight however not so tight as to deform the hub. Sounds crazy I know that’s why I have since gone to an aluminum hub and I don’t have this problem anymore. Hope this helps.

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