Vibration after lift off - Page 3

PCHunt · #21 09-10-2020, 04:09 AM

Next time it happens, just touch the brakes and see if it stops.
If it does, one or both of the MLG tires might be out of balance. If it continues, it is likely the nose wheel.

If the vibration only lasts a few seconds, one solution is to call it a "feature", and not worry.

Piper J3 · #22 09-10-2020, 08:14 AM

To isolate front wheel as source of problem, perform a touch/go without letting nose wheel touch runway. Try to make landing nose-high and gentle as possible to not set cantilever nose gear in springing-oscillation. I do the touch/go without flaps to allow smoother departure. The idea is to have main wheels spin-up but not nose wheel. Small wheels spin fast so any out-of-balance is pronounced. I use automotive stick-on weights on the inside wheel rim with no problems. Also, keep in mind that static balancing is not as good as dynamic. You may have to move weight L-R to compensate for imperfection in tire/wheel assembly. A little trial and error go a long way…

AviatorMav · #23 12-02-2020, 07:56 AM

Any more movement on this issue? I too am experiencing the same vibration. Occurs on climb out (150-300 ft AGL) for 2-3 seconds. I have a habit of tapping the brakes so I doubt it is the main gear. Nose tire seems the most likely culprit.

funflying · #24 12-02-2020, 08:17 AM

I experience the same vibration and believe it is the nose wheel. I balance it as best I could about three years ago but to me it could be better. Annual is coming up and I will rebalance then

AviatorMav · #25 12-02-2020, 08:19 AM

Glad to know others are having the same issue. What is the best process for checking/adjusting the balance on the wheel?

Piper J3 · #26 12-02-2020, 09:17 AM

Have you tried the test as outlined in post #22 above?

Hotscam · #27 12-02-2020, 02:27 PM

No results for me yet
Tried most I could think of but nothing stops the vibration
Typical just after take off at 200-300 ft for 1-2 seconds.
Brakes make no difference, wheel perfectly balanced. Flaps or no flaps.
Anybody tried without nose wheel fairing ?
With the new fork the incident angle is quite different and it may induce lift

AviatorMav · #28 12-02-2020, 08:27 PM

I also think the nose fairing could be an issue. I just recently purchased my RV-12is and the previous owners did not have the fairings installed. I had them installed before I picked up the airplane. I asked them about the issue and they hadn't experienced it. Which makes sense. They hadn't flown the new nose fork with the fairing installed.

seagull · #29 12-02-2020, 09:25 PM

I would almost guarantee it is the nose wheel balance. Here is a quick way to check.

Tilt your plane back and put it on the front saw horse only. This lifts the nose wheel off the ground. Remove the faring (if you have one).

Now spin the wheel up to rotation speed, about 50 mph. The easy way to do this is with a 3000 RPM variable speed drill motor. Put a 6" sanding disk backing plate in the chuck, (no sand paper). Run the edge of the disk against the tire tread to bring up the rotation speed of the tire. Then back away and let the tire spool down. If the tire is out of balance you will know. You will probably be afraid to fly once you actually see what is going on with an imbalanced tire.

PCHunt · #30 12-02-2020, 09:30 PM

Or, you can call it a "feature", and press on, as I did.

Now, if it DIDN"T shake briefly, I'd wonder what's gone wrong!