I am having trouble adjusting my blade tracking _ am almost positive my main shaft is not bent, and I replaced the spindle. If I adjust the link 1/2 turn on the high blade it is then lower than the other one - I could get them perfect before! How much would be aceptable - 1/4 - 3/8"?? What else could be causing this - also, what are the o-rings where the spindle goes through the head for?? Can they be replaced with bearings?

Another question - can I replace the flybar with same sized piano wire, or will it be too flexable?? Could a slightly bent flybar keep me from getting perfect tracking??

No one has any comments? (I hardly believe that, knowing the posters here!)

The blade tracking beign off and not adjustable can be caused by warped blades. They are wood and large temp changes can cause them to warp. I would sight down the TE of the blades and make sure they are straight. Another thing that can cause this is to stiff of head dampening. I have a feeling that you allready have the bearings your talking about in the head block! Put the o-rings back in so you have some head dampening. The o-rings help take out the vibration and make the cyclic control not so sensitive around center. They also allow the balde to self adjust the tracking somewhat. Basicly when your inbetween 1/2 turns on tracking the head dampening will take care of the rest.
Jason

Still got the o-rings - the blades are brand new plastic flat bottom. I will check the straightness though.

Mike,

Make sure you lubricate the O-rings & the feathering spindle, use a light grease, Vasoline works OK. Lack of lubrication on the O-rings & feathering spindle can cause sticking, that will cause the blades to jump and/or cause tracking issues. Add some to the center-hub as well.

Rick

I am using a lithium soap grease.

Another thing that will mess up the tracking is a slightly bent feathering shaft. If you have a crash on your current one then try a new one, and check the flybar straightness and paddle alignment while you're at it.

Mike,

You NEED the o-rings to dampen out Vibrations. When measuring tracking, don't forget that as you increrase throttle, you are also increasing blade pitch. Instead of looking head on at the blade disc as" _ ", you are looking at a " \ " profile. need good contrasting color on one blade tip. Also, something sticks in my mind that you are supposed to bring the low blade up to match the high blade. Could be wrong about this, if so, maybe somebody will jump in.

Yes, most definitely, bent flybar will add vibration. So, will off axis paddles at zero pitch! With zero blade pitch, make sure that both paddles are at zero pitch also. Use a caliper to make sure that the paddles are equidistant from the hub.

good luck
Splat

I don't want to be a "buttinski" here but what you said in the quote above, was that after you tried readjusting or a simple check of things after reinstallation?

After adjusting - new spindle - flybar is centered and level.

Also, Splat - I believe you bring the high blade down - however, there comes a point where both blades might be too low, and it would take excessive headspeed/throttle to get it off the ground. I will measure the linkage length against the manual (darn, need to get a good dial caliper!!)

I pulled this out of AMT for you. Even though they are talking of fullscale, some of the main principles apply here.

Vertical Corrections
A vertical vibration is a result of unequal lift produced by the main rotor blades. There are two primary adjustments utilized to correct for a vertical vibration. The first is the main rotor pitch change links (PCL). The PCL controls the angle of each main rotor blade individually. To move a blade up or down, lengthen or shorten the PCL for that blade. This adjustment is typically used to correct for the vertical blade separation on the ground and the vertical vibration at hover. The second adjustment available is the main rotor trim tab. To make a blade fly higher or lower, move the trim tab up or down. The adjustment of trim tabs is primarily used for in-flight corrections. Trim tabs are very sensitive, and it is important to use care and caution when making adjustments. One point to consider when making track adjustments is that as you change a blade path, you will either increase or decrease the amount of that blade's drag. This change in drag has the tendency to move the blade forward (lead) or aft (lag) of its original position. As the blade pitch is increased, drag is increased, causing the blade to lag. If the blade pitch is decreased, drag is decreased, causing the blade to lead. This lead/lag effect results in a change in the lateral balance of the rotor disk. Thus the adage, "track affects balance" is realized.