MMatheny

AxeCP

I have a blade tracking issue (no, I didn't test it with my shins this time!!!) and I'm wondering what order I should test parts in. Since the feathering spindle is weak and easy to remove, I thought I would test that first. Next would be the main shaft - is there an easy way (without an runout gauge) to test whether the main shaft is bent? Preferably without removing it since it is such a PITA to remove! I also read that adjusting the linkage from the blade grip to the flybar carrier will correct tracking errors if there is nothing bent - true?


Also, is there anything about how to trim it! I have to add about 2-3 clicks of forward cyclic and would like to mechanically trim this out so I don't need to add any trim. What about setting the trim on the other axes? My goal is a hands-free hover.

flag8r

As far as mech setting your heli...make sure the swash is level, adjust any linkages going to the swashplate to achieve this...this should give you a close to hands off hover.

osterizer

The quick and dirty runout test is the magic marker-- take the head off and run the mains up to a moderate speed (doesn't have to be too great), then take a sharpie or similar and bring it slowly to the side of the shaft near the end. Take it away quickly when it brushes the shaft, then turn off the motor. If you have a line all the way around the shaft, there's no runout worth mentioning, but if you have a shorter dash, then the shaft is bent toward the center of the dash.

All that said, if you take the head off and spin the motor up a bit, and you can't see any runout, then you probably don't need to worry about it anyway .

123Splat

You MUST balance out the head/main shaft first. You can use Osterizer's in situ test with much success, if you are carefull. Pulling the shaft and doing the roll test (roll the shaft on a sheet of glass (from a 8 x 10 picture frame works well) and look for high centers) is the best and most reliable (without actually checking run-out with a jig and guage).

You may see SLIGHT button wobble when you power up (indication of imbalance or bent shaft). This is usually caused by imbalance in head components. If it goes away with increase in throttle, it is negligible and can be ignored.

Don't even bother with tracking adjustment until you get the head reasonablly stable without the blades installed. Then go to Blade balancing. Be sure that you have the tension on the blade grips set equally as per the instructions in the manual. Then try to get the blades tracking (by adjusting the small linkages to the see-saw.

ONLY AFTER headis stable and blades are tracking, should you attempt to adjust the linkages to the servos to mechanically trim out the forward drift, if you want... Your bird should be a little nose heavy. You may increase/reduce that some by moving the battery further out/in, if possible. Unless the bird is way out of trim (2-3 clicks is not far out), I would suggest NOT attempting mechanical trim.

Hands-free-hover is everybody's goal. Goals are good things, even if they are unattainable....

Splat

USHobbySupply

this is an interesting method by soloboss to check for shaft straightness. I think its a pretty good solution, as the out of round would be magnefied visually, allowing easier detection and extra sensitivity to small variations.

http://www.rcuniverse.com/forum/m_63...tm.htm#6404250

MMatheny

Great info - wonder where that Heli Setup site he mentions is??

MMatheny

Another setup question - my gyro gain is turned all the way up - came from the factory like that. That doesn't seem normal. I don't get any tail wag, which I wish I could get so I would know the setting wasn't at one extreme or the other - I wish I had some more gain to play with!

Also, which direction increases gain? The manual states the bias and trim directions, but not the gain!!!

123Splat

Mike,

That sounds like a good test. Might be a little difficult to set up with an Axe, but certainly worth trying. Thanks for the heads-up.

MMatheny,
I seem to recall reading that it is Counter-Clockwise to increase sensitivity. Be sure to mark the original setting with a Sharpie pen, so you can 'follow the bread crumbs home". And, Remember to power down and back up (unplug the bat for 10 seconds or so, then replug) after making adjustments (something about letting the circuits re-initialize after adjustments).

Splat

MMatheny

OK, if that's right, then my sensitivity is turned all the way DOWN (CW)! I'll experiment and report my findings.

MMatheny

Would be nice if they included that info in the manual!

MMatheny

NOPE - CW! With mine turned all the way CCW, my tail motor barley wants to kick in - so mine was turned all the way UP from the factory (CW) - I don't get a wag, but careful adjustment of the trim pot locks it pretty well (until the battery gets low!)

MMatheny

OK checked the feathering spindle and main shaft last night - no perceptible run-out. Changed the feathering spindle anyway and also put new plastic blades. Put different colored tape on the new blades so I could see which blade was where, adjusted the blade grip linkage to get them right in line, put 1/4" of cardboard behind the battery to move it forward to compensate for the 2-3 clicks of forward cyclic trim I needed to add (reading about eCCPM adjustments, seems I would have to adjust all 3 servo linkages to adjust the forward cyclic issue, so I took the easy way out!). Anyway, man, what a different flying bird! Not bragging, but hovering it in my 10X11 dining room is a cinch, I can even swing it around like it's on a pendulum, and after the battery wears down a little, it will almost hover hands free!

Guys, learn to trim your heli properly, and I will almost guarantee you will be a better flier - the heli isn't designed to fly anyway - an out of trim situation just multiplies that tendency!

MMatheny

Well, took out a heli book I bought a while back, and even though it was written 12 years ago (they stated that electric helis do not have the power to be worth the money - man, how that has changed!) I picked up some good info.

When adjusting blade tracking, always try to bring the high blade down, not the other way. Also, if you want to bring your head speed up for more gyroscopic stability, adjust both blades to have a slight negative pitch - say, 1/ 2 turn at a time. That way the head has to spin up a bit faster before it reaches positive pitch.

PilotLight

My Feedback: (1)

Good Advice. If you bring the lower blade up, it will result in lower head speed. For the guys with computer radios, the head speed can be adjusted with the pitch and throttle curves.