Is This Normal Vibration??

[lperagallo]

I spent today trying to fine tune the Bergen. This is after adding a Bergen Muffler and Raja's generator. I was also trying to get the GV-1 running correctly. I was leaning out the low needle after starting at 1 3/8. It was running good, idles nice, good headspeed, little vibration. When hovering, I looked at the vertical tail fin I noticed a vibration on the end of it. I continued to lean out the low side and the vibration got a bit better.

The big question is: Is it normal to have a slight buzz in the vertical tail fin? :dontknow I also have some vibration in the cheeks on the canopy, but I attributed most of that to bad mounting holes on the canopy. I drilled them out too big and have huge rubber grommets with a sleeve put in to get 3MM bolt to attach correctly. I have balanced everything i can think of. There is no tail kicking the 401 holds fine. What should I be checking?

[Gary Travis]

Richen the low end
Gary

[cbergen]

AND TURN THE GOVERNOR OFF!!

At least until you know it's tuned properly....

[Gary Travis]

Chris is correct on the govenor, you'll never ger the needle right when running the govenor. set the needles and then mess with the GV 1
Gary

[MarkWebber]

I had a bit of a buzz until Gary tracked my tail blades for me at IRCHA.
Of course, start where they say.

[lperagallo]

Chris, All my tuning is being done with the governor off. I took your advice from last time and have tried to dial the engine in first. I still haven't had any luck with the governor yet so I have it turned off completely in all flight modes.

Gary, It appears that it vibrated less with the low end needle leaned out. I am probably at about 1 1/2 now. I really didn't want to lean it out anymore for fear of smoking the engine. I followed your video and think that I have it four stroking a bit on spool up with it smoothing out at about 1/4 stick. What I'm concerned about is that I think the engine is running fine, I just have a slight buzz in the tail. Should the tail fin be perfectly still or is some buzz acceptable? :dontknow

[rbort]

1 1/2 on the low needle is still on the rich side in my book. I think you can safely lean another 1/4 turn with no fear of smoking the motor.

If the buzz in the fin persists, you can try to pull the rotor off the back of the motor (drill a piece of solid steel and screw into the rotor with two screws evenly to pop it out after removing the starter dog) and balance it if its not already done. Just like balancing the fan, you would have to drill dimples/holes in the back of the fan on the heavy side when checked on the high point balancer. In most cases you will find the rotor to be off balance, and this procedure along with other things helps to eliminate the buzz in the fins.

-=>Raja.

[Helimex-Rafael]

I had the same problem, after getting what I think were the right needle settings, I had a slight tail vibration, until I found the tailrotor output shaft was slightly bent,(never crashed, but hit a door taking the heli outside my house). I changed the shaft and the vibration went away.

[kelly steed]

Don't get caught up tuning your heli acording to what your tail fin does,Take the fin off,set your hover head speed and low needle,It's ok to get one or two tail kicks.Now go set your high needle,Get your picth and carb set so it pulls and hard.Go back to your low,if the kick is gone get it back,now take it away this will be hair turns on your low.Now go burn three or fore tanks,push your chopper hard,look at the overall performance,You may want to make changes to your head speed,pitch curve.When you feel you like it,and can't stop smiling,go burn more gas.Put your fin back on.I use my tail fin so that my blades don't hit the ground,yes I get the vibs,they come and go.But I can't count how many times I bounced that long tail off doors,walls.Work on one thing at a time,don't burn yourself out on alittle buzz.I use the twin tail fin chopped narrow because Ilike the length and it's thicker,so I need something way out before Iget the buzz.

[lperagallo]

OK....so as I'm going through everything step by step to make sure that I have everything set up mechanically sound I find a stupid newbie mistake. :arggg: When re-installing the main blades I find that I didn't put in the brass sleeves in the blade root to make the blade bolt fit properly. There was a little slop in the blade bolt. I had to insert the small brass sleeve to make the bolt fit tightly.
So the question is does this cause vibration or any other weird things? :dontknow
I would think that once the head was up to speed it wouldn't affect things much because of the centrifugal force, but I have no idea. What effects do you think it would have on overall vibration and or performance?

[lperagallo]

Well, I had a chance to test the Intrepid today to see if maybe the tail blades were not tracking together. I also have the sleeves in the main rotor blades. Lo and behold, most if not all the vibration is gone. The tail blades are tracked fine also. So I guess most of the problem was the main rotor blades. :oops:

I did run into a familiar problem with the engine. I was hovering and all of the sudden the engine picked up RPMs without any stick movement, then slowed down. I shut down went to the bench and took the carb apart. Once again the screen is pretty well clogged :bomb: Second time around. My first gas can set up didn't have a gas filter and I pulled some crap out of the tank. I went out and bought a Jersey modeler fuel can that is a complete set up with ceramic filter in the tank and viewable external filter. Hopefully this will keep any garbage out of the tank.