Lepton EX Vibrations. Advise needed.

[t-rexn8]

Hello. I have recently finished my Lepton and am struggling with vibrations. I am running the Kora 15-14 with 21t pinion, mah blades balanced and 68mm balanced tail blades. I have been able to eliminate most vibrations on the ground but as soon as I go into a hover the vibration sets in. It is a high frequency vibration. I also noticed on spool down the vertical fin moves up and down a little making me think its in the head. I have oiled my dampers with silicone oil and checked all thrust bearings. I have also balanced the tail blades in the feild with small pieces of tape over and over again. I only tightened the belt untill it would not slip. I am starting to run out of ideas and would appreciate some advise.
Sorry guys I forgot to mention that I am running a 5S 3700.

Thanks everyone,

Nathan

[ArthurKnowles]

High frequency vibrations are generally tail rotor related. So that's where I would start. Check:

Basic Balance Check: by removing the tail rotor assembly and use a High Point or Robart balancer.

Mechanical Check: by pulling the blade holders to make sure there is no free play. Twist to assure they mosve freely. I always oil my bearing with Triflow or similar light oil.

Blade Check: by verifying no blades are damaged and have a similar airfoil shape.

[Jafa]

Yeah - but the Lepton head is pretty high rpm
The Lepton dampers pinch the spindle very tightly
Many of us have had problems with this
Some of the Hirobo Lepton white blades are a contributing factor also

[t-rexn8]

OK. Went down to the 19 t pinion with the 15-14 and 5s and vibes are gone. I think I was passing the rpm limit of the heli. Now all is good and I can confidently say Im a satisfied Lepton owner.

[Rush]

t-rexm8 - what headspeed where you starting to get vibrations at? I'm basically interested in putting together a Lepton as well. so been looking at posts to see what problems people have encountered.

As basic add-ons, i understand that i'd probably need to buy

68 mm tailblades
new CF tail fin set to replace the stock plastic ones.

The setup i'm thinking is
Gyro & Rudder: G770 x DS3400G
Cyclics: 3xHS85BB or MG
Motor: Kora'15-12, 24T pinion
ESC: CC45HV
BEX: CC BECX 10 A
packs: FP 4S 25C 3700

I have two trex's and kinda used to HS of 3000+ rpms. I understand the Lepton has issues above 3000 rpm so i'm trying to get more info on it.

Appreciate the help, TIA,

Regards,

Rob

[rotodingo]

I got vib problems above 2800 rpm. It comes and goes. One day yes, another one not. In fact it's more the HS the vibs appears that changes.

I think Hirobo is right about the 2600 rpm for 3D. i think 2800 is the upper reasonable limit.

Nicolas

[prototype3a]

I had problems with my lepton anytime I exceeded 2900 rpm. At one point we tached my lepton at ~3200rpm. I also had +14 deg of pitch. Made for a real rocket ship. ;) I fixed this problem by putting bungie cords on the landing gear to damp the vibrations. I have since changed pinions, reduced my headspeed and fixed my pitch range. I also switched to the Gaui Hurricane 550 landing gear. It was kinda fun to punch around but it wasn't much fun to fly. Now it is fun to fly and the flight times are much better.

[Rush]

I get vibrations at 2600... I just oiled the dampers. Hopefully that will fix the problem and allow the spindle to move freely. Using Rotortech 430 mm CF blades and these balanced wo within 0.1 grams