lyk2fly

My Feedback: (3)

Hi all, I had a bad vibration sometime ago and re-tracking the blades seemed to correct it. The strange thing was that I was using 2-4degree grips and to get proper tracking the rods were not the same length.....when at the same length the blades would not track properly. Anyway all was well.....until this evening when I had the urge to fly. The heli vibrated horribly. I then re-checked the blade tracking and it was once again out......requiring more uneven rod adjustment.
The heli has been sitting in the house.....after the last time out.....what happened????What changed????? Also this time when the blades were finally tracking the vibration did not stop. I fooled around with it until the sun set..... all to no avail. HELP!!!!!!!!
Mark

darthdrk

Sounds like warped blade(s) or and feather plate. It does matter how you store the heli when not flying. If you store the heli with the blades folded back and unsupported, thats not good. i find its best to store the blades fully extended. Im still flying using the original feather plate.
Those plastic parts can be rather heat sensitive when stored for lengthy periods of time in a certain position.

KLRico

Good call...

I have the same problem. I used to store the heli in a closet on a modified hanger by the skids so the helicopter was vertical and the blades hung freely downwards. Nowadays I often store it with the blades folded back but I usually move the swashplate aft so the blades sort of rest on the boom. The blades will be in track one day and out another, never could figure out why...

Do you suppose a blade holder that clips onto the tail boom would solve these problems?

darthdrk

A blade holder may solve this problem If you cant store the Heli with the blades extended as if you were ready to fly.

lyk2fly

My Feedback: (3)

Thanks for all your help, I'm going try one more time to correct the problem. If it is the feathering plate would it be better to store the heli with the blades removed?
Thanks again,
Mark

darthdrk

That would probably be the best way to store the Heli. There wont be any weight on the feathering plate.

lyk2fly

My Feedback: (3)

Good news and bad news......both of them were my stupid #@$%^&# mistakes. I had the Z links in the wrong holes. When I moved them to the outside holes things improved remarkably. Man it was smooth! I do have an excuse though.....I had to have glasses (a forties thing)......you do have to be able to see to enjoy this hobby. Anyway the heli was back to its old self......a delight to fly.....and with the new Darth canopy I was amazed at how good it looked cruising thru the air. Now for the bad news......I even hate to admit it......my left/right cyclic servo decided to quit in mid air. It even gave me warning but I just thought that the wind had pushed the heli around while at a high altitude......and kept on flying. The servo had been moving in jerky movements for some time....how many times have I said that if a servo is acting suspicious that you should not fly until you fix or replace that servo? So the servo had warned me twice.....still I flew. You simply cannot land without left/right cyclic control.....so I crashed......with my new Darth canopy...*&*%^$$###. Anyway the canopy held up better than the LMH canopies do in such a crash. Actually it had very little damage....the only other things were a lost Z link and some slight damage to the landing gear..*##$^@#*.
Hoping one day to learn this hobby,
Mark

darthdrk

Dont feel to bad, I had a wreck today it was completely my fault. I decided to install a new crutch and mainshaft in my heli. IE This was just about a complete build over. I got everything together and I thought i checked everything out and it seemed ok. well, I was in a rush because I was loosing daylight and wanted to fly. Got the engine started. Im kinda use to hitting the throttle to hover speed and when I did, the heli did something that I hadnt planned to do. well, it wrecked (no damage except broken cheap zip ties on the landing gear). Looking the heli over real good, I had the fwd/aft cyclic control linkage on the wrong side of the servo which meant when I push the stick fwd, the blades would tilt backwards(not good) The biggest DOOOH!!! was my tail rotor servo was plugged into my cyclic left/right and vise versa. Talk about feeling like a dummy. Well, I got everything straightened out all is well now. Was able to get in two tanks of gas worth of flying. I had to put an LED on the nose so I could tell the orientation of my heli. It got a little dark on me. Ill see what tomorrow holds.

lyk2fly

My Feedback: (3)

Well......I don't feel so bad after all. I will pick up a servo at the lhs and I'll also see what tomorrow holds. Man that thing looked GOOD! Good work on those canopies darth!
Mark

lyk2fly

My Feedback: (3)

OH BOY....OH BOY.....OH BOY!!!!! Just got back in from flying a couple of tanks. Everything was great!!! New servo on left/right cyclic and gears replaced in fore/aft cyclic servo. Smooth.....even has a cool rotor wash sound since the vibration is gone......watch those z link holes everybody.....I will now that I can see them
Mark

flyinrog

My Feedback: (1)

Hey Mark, good to hear, I got the 40 something eye problems too, havent flown mine in like a year,still has the training gear on it..been working on my plane skills mostly,,but I read stuff hear to keep up to date.......Rog

Playfair

My Feedback: (5)

I too have noticed that the arms are different lengths using both 4deg grips... The heli is flying pretty good, except it shakes below hover speed. Didn't think this would be a prob, except it happens during decent, especially if there's a wind! Then the gyro starts tweaking out...

Upon close observation, right as it starts shaking, the blades are out of track. I set them up for hover speed, but now it looks like a compromise is in order. The hub and feather plate are new. I do use a DIY blade holder cut from styro as well.

Any thoughts?

lyk2fly

My Feedback: (3)

Hi Playfair......I wonder sometimes about the M.R. blades themselves.....are they true to each other?(pitch) Also I wonder if balance is out, will that appear as not tracking properly because of the resulting vibration? Just thinking......of all the things to learn about this hobby I believe that the M.R. assembly is the most difficult. Stopping vibration is a real pain to me......there are so many things that can cause it.
Mark

KLRico

Tracking down the causes of vibration is definately a big PITA!!! Dozen diffrent possilbilites... Subrotor pivot rod bent, main shaft bent, tail drive wire vibration, tail rotor out of balance, and so many more.

I let someone with only simulator experience fly my LMH and he crashed it pretty hard. Main damage was to the subrotor. Never broke that one before! After replacing it there was much less vibration. So I got to thinking that perhaps the old one, which was as old as the heli (4 yrs) maybe was warped or something and that could cause a out-of-track conditon.

Most of the time, as long as the fuel isn't jumping around inside the tank too much, I'll just call it good.

Playfair

My Feedback: (5)

Update to my "sub hover speed" vibration problem- SOLVED!
I was paranoid having the swash plate bind to the universal ball, so there ended up being just enough play that any imbalance of the MR assembly was amplified, allowing the tracking to actually vary with head speed. I tightened up the fore/aft control arms until the plastic swash arms just start to deflect, and it's smooth as silk. The bird is so well behaved (and tight) now that I don't want to even fly it! (at least for a few hours) lol

lyk2fly

My Feedback: (3)

Here's the story......all was well but each time I flew it seemed that the vibration was coming back.....little by little. Today it was so bad that I just quit flying. Fuel was jumping around so bad in the tank that the engine ran lean and stopped in mid-air.......about 20' high. No damage though. What is wrong with it!!! I am storing it with the blades removed......but if you check blade tracking it changes and you still have to readjust it......and it still vibrates. I tried it with the M.R. blades removed.....it still vibrates!!! I would blame the M.R. shaft but I cannot see anything bent about it. I figure if it vibrates with the M.R. blades removed then the feathering plate is not to blame? Something in the subrotor assembly?? Hub??? Or should I just get a new M.R. shaft and try that???? It's the worse thing I've come up against in this hobby.....much worse that nose in hovering!!!
Wanting to fly but can't
Mark

KLRico

If you wish, you can check the MR shaft by removing it and rolling it on a piece of glass.

lyk2fly

My Feedback: (3)

I removed the rotor assembly and checked the M.R. shaft. I rolled it on a cultured stone counter top with a flashlight shining behind it. You could see a light/no light pattern as it was rolled. I worked with it until the light/no light pattern stopped. These variations were very slight and toward the middle of the shaft. How much is too much? I would call this a variation rather than a bend. I also replaced the crown gear......it had been damaged in a crash months ago. It looked good to the eye....but the crash had caused the plastic gear to separate from the metal collar (I had just pushed it back together). So while I had everything apart....and I had a new crown gear anyway..... it seemed like the thing to do. I put everything together and it flew good. The vibration is practically gone (I'm almost afraid to say that). I do still have uneven adjustment on the rods to get the blades to track good, so I guess I have a warped feathering plate. Am I correct to assume that there will always be some slight vibration?
Mark

KLRico

I don't think it's possible to get rid of ALL of the vibration. Everything would have to be perfectly straight and true, and each rotating part would have to be balanced to .01 grams, etc etc. By then, you're dealing with engine vibration more than anything.

If the fuel isn't jumping around inside the tank, and the canopy is shaking off the mounts, be happy and go flying.

darthdrk

I bought my heli a couple years ago, I went through the balancing proceedure, added tape to one flybar and it still didnt balance out statically. I took all the tape off and ran it up and it was fine. I think all that balancing proceedure was a waste. Static balancing seemed to me to be misleading. To this day i dont go through the balancing proceedure even when replacing blades. If the parts are molded about the same, there shouldnt be that much off as far as weight goes. The plastic density should be about the same if its mold injected. Well, to make a long story shorter, i put on the new parts and seemingly to me everything tracks fine and rotates fine. Most of my vibrations has come from crashes which means something got bent. another source of vibration I had once was a result of blade lag. I had to tighten up the blade grips about the same tightness and when I did, the vibe was gone. also a bent tailrotor shaft could cause a vibe too.

lyk2fly

My Feedback: (3)

Darth, I too don't put much "stock" on blade balancing. I have rarely seen it reduce vibration. I believe that the blades are close enough when molded. How much vibration do you allow? I still have a small amount......one landing gear shakes slightly but the tail fin is steady. At what point is a main rotor shaft considered bent? Checking the shaft as I did would you have called that a bent shaft? I do know that something.....main shaft or crown gear......improved things alot. Just trying to figure this vibration thing out so that the next time it will be easier to fix.
Thanks
Mark