Need help with V120D02S V2

[fergo84]

hope someone can help...

i completely screwed up my heli. bought a microheli frame. did the change, and i guessed i screwed the up the connection of the servos to the receiver.

now my heli does not fly. everything seems to be off. can't lift off. roll become pitch etc. only thing working correctly is the throttle and rudder.

wanna clarify the servo connection.

1. front servo = elev
2. port side servo = aileron
3. starboard side = pitch

also, what swash type should i set. (using a devo 8s) normal 1 servo?

im a complete newbie. just started with CP helis.

[SkyKraken]

I don't remember port assignments, but the swash follows the stick.

Thus,
left cyclic and the swash tilts left
right cyclic and the swash tilts right
forward stick and the swash tilts.... you guessed it forward.

the tail is a little harder to explain.
the tail pivot arm will move opposite the rudder input is easiest to comprehend.
thus left turn, pivot will appear to move right.
yet leading edge of the tail blade will pull the tail right, to move the nose left.
hence a "left turn".


I'd make sure you have plugged in the motor correctly, the plug upside down will turn the motor backwards and it would act as you described.

Clockwise is correct.

Normal swash is correct.

The v120d02s V2 manual is online somewhere if you think you have messed with the settings and don't know there required values.

[fergo84]

I'm pretty sure the motor is connected correctly. I can tell the pitch because when I input right cyclic, I can see that the landing skid flex as though u apply force on the rotor head (negative pitch)

But nonetheless, appreciate ur comments. I will have a look again n do some search.

Thanks a lot!!!

[SkyKraken]

I assumed mode 2 helicopter controls.

on the v120d02, i believe the collective is backwards, down is up, up is down.

Positive pitch occurs when the swash drops.
Negative pictch (flexing your skids on the ground) the swash moves up.

"Right cyclic" should not "flex your skids", it should tip over by lifting left over right.

good luck.

[fergo84]

thanks for the input. i just couldnt figure out which servo goes into which port on the receiver hence im getting the wrong control output.

but ive managed to sort it out. i actually put the AIL and PITCH opposite.

and now i just realise i have a loud grinding sound when i hold the heli and power it up and input rudder. The funny thing is the sound only comes when i input rudder to one side. the other side is ok.

is this normal?

[Get_To_Da_Choppa!]

A loud grinding sound from the tail is never normal. Check your tail shaft for side play, check your gear mesh, look for binding around the pitch slider at the rudder servo's travel extremes, and make sure the tail blades aren't hitting the boom at full travel. You may have to back off the rudder extents pot on the RX a bit if there's any binding.

Assure that your rudder is setup correctly: With the heli sitting on a smooth surface and the tail gyro setting on your TX at 50%, the heli should rotate slowly on the ground in a clockwise direction as you spin up the motor. That will get you in the ballpark to tune away any slow tail drift in a hover. Don't forget to set the gyro back to ~75% when you're ready to fly.

I recommend loosening the two main motor screws and moving the motor so the pinion gear disengages from the main gear. This will allow you to spin the rotor freely by hand for several seconds without any cogging resistance from motor so you can find and correct any rough spots in the gear mesh, etc.

You can adjust the drivetrain tension by moving the tail assembly in or out in very small increments. Too tight and the gears with bind; too loose and their D-holes will strip on impact. You generally want the boom pushed all the way into the frame, but pulling it out a millimeter or two in order to relieve excess gear tension is okay.

When you reengage the motor, be sure to allow a very small amount of play between the motor pinion and the main gear to avoid binding.

[fergo84]

Great info... Thanks.

i noticed that my tail boom is loose. Cant tighten it anymore. (not align with main frame. its tilted slightly up after a mild crash) Shift it back to level and the noise goes away.

i was into RC Cars many years back. So i still use the same method using a piece of paper between gears to ensure correct allowance. still works on helis.

[Get_To_Da_Choppa!]

The carbon fiber booms split pretty easily along the glued seam in a crash and the crack can be hard to spot, but gently twisting the boom to check for a lack of rigidity will usually reveal a split. Sounds like it's time for a new one. While you're at it, make sure that the drive shaft isn't bent by rolling it on a flat surface, preferably something like a sheet of glass. The slightest bend can cause all kinds of problems.

FWIW, when working on the tail, I find it easier to remove the entire tail assembly, including the drive shaft bearing behind the A gear, from the frame in one piece. You can then swap gears, etc., grab the A gear and spin the shaft to check for smooth rotation and pop the whole assembly back into the frame when you're finished.

[fergo84]

Originally Posted by Get_To_Da_Choppa!

The carbon fiber booms split pretty easily along the glued seam in a crash and the crack can be hard to spot, but gently twisting the boom to check for a lack of rigidity will usually reveal a split. Sounds like it's time for a new one. While you're at it, make sure that the drive shaft isn't bent by rolling it on a flat surface, preferably something like a sheet of glass. The slightest bend can cause all kinds of problems.

FWIW, when working on the tail, I find it easier to remove the entire tail assembly, including the drive shaft bearing behind the A gear, from the frame in one piece. You can then swap gears, etc., grab the A gear and spin the shaft to check for smooth rotation and pop the whole assembly back into the frame when you're finished.

some spare tail booms are on their way as we speak.. hahah
thanks for the advice. will definitely do it the right way to prevent unwanted tail issues.