If I throttle hold 3-4 feet from the ground my tail doesn't hold, and swings around about 90 degrees. Also when I do pitch pumps, the tail wags, like my gain is too high, but my gain seems fine during hover and flight. I can't figure it out.

My gyro is a spartan ds760. I've setup headholding in rate mode with 0 pitch on my tail. I'm wondering if this should be 8 degrees or so maybe, I'm yet to setup rate mode, but I'm thinking my heli would fly better with the gyro having to correct for less pitch, and the tail mechanically holding more naturally. If that makes sense.

When you hit the TH, the nose goes right, right? That's because the tail can't release the pitch fast enough (your reaction force goes from "something" to ZERO in a fraction of a second) - you need a faster servo, or perhaps you've set the servo arm length incorrectly. Impossible to say without knowing something about this situation other than a Spartan gyro - that isn't enough information. You could have a Spartan on a 1/2-scale turbine Apache for all we know.

Originally Posted by jasmine2501

When you hit the TH, the nose goes right, right? That's because the tail can't release the pitch fast enough (your reaction force goes from "something" to ZERO in a fraction of a second) - you need a faster servo, or perhaps you've set the servo arm length incorrectly. Impossible to say without knowing something about this situation other than a Spartan gyro - that isn't enough information. You could have a Spartan on a 1/2-scale turbine Apache for all we know.

The nose goes left, tail right. The heli is a 450 exi pro (belt), the ball link is 10mm out on the servo arm. The servo is an align ds520, not the fastest I know. The reason I figured it might be my spartan gyro is because I don't remeber this happening with my detrum gy48v gyro I had on before, same servo same zero pitch tail setup in rate mode (setting up HH).

Maybe your gain value is different/wrong in hold mode?

Originally Posted by jasmine2501

Maybe your gain value is different/wrong in hold mode?

Possibly. I'll have to mess around with it more I guess.

My more recent problem today...now I can't figure out why my blade grips keep coming loose off the head. I use loctite. I've been working on my heli recently so I'm wondering if something is causing too much vibration. I've only had one short hover test since the work, and I haven't had a chance to track my blades yet. I'm wondering if the blade tracking is causing the vibration. But I'm not sure it would be enough to unscrew the blade grips... but maybe. Like I said, I only basically spooled up to test hover, my elevator servo gave me problems and I was able to land safely, but when I landed I noticed the blade grip coming off.

you clean out the threads on the screw and feathering shaft to get the oil out of it?
if not the loctite wont set

Originally Posted by Elios000

you clean out the threads on the screw and feathering shaft to get the oil out of it?
if not the loctite wont set

I'll try cleaning it really good, see what happens.

Also thread lock compound can go bad so maybe get some new and try that. Use new bolts and shaft when you do it.

will do, thnx

There is also grease tolerant thread lock. It's not great for some things but if I have trouble getting it into a spot like a feathering shaft, that is a good place. I also use a toothpick and put the locker in the hole, not on the bolt. You don't want to have it come off in flight - don't ask me how I know.

Originally Posted by Blade Crasher

There is also grease tolerant thread lock. It's not great for some things but if I have trouble getting it into a spot like a feathering shaft, that is a good place. I also use a toothpick and put the locker in the hole, not on the bolt. You don't want to have it come off in flight - don't ask me how I know.

I use a toothpick too, and put the thread locker in the hole. Anytime there's plastic or bearings nearby, I do this.

Well, I'm testing it today again, we'll see what happens. I think there might have been to much old dry loctite on the bolt, so I'm using a new one anyway. And there did seem to be dirty grease on the bolt too, in what wiped off with a paper towel. We'll see what happens, I'm pretty confident, but then again I was confident last time too when the grip almost came off. I hope my grips don't come off, that would suck.

Meanwhile, I just put an align main gear set (w/bearing & everything) on and I'm amazed at the performance vs the exi stock. It's smooth, the gears mesh better , and way less shakes starting up and everything. A lot quieter too! I think I'll be buying a trex 450 soon.

If you have a problem with main blade grips coming loose, even if you use threadlock and you use it correctly, big chance you have a bearing problem in that blade grip.

I am not particularly careful when applying threadlock, and my bottle is over 10 years old (took it back from work that time and no idea how long it was allready in use or how it was stored previously) but never had anything coming loose that was secured with that. And I fly a lot, and plenty different heli's, and work a lot on heli's, not only my own....
I feel comfortable with it, just because I know (and have tested and confirmed numerous times) that even that bottle still provides absolutely sufficient security, even in big gassers with their high vibration levels.

I also work a lot on helicopters for other people, and I have seen more than one blade grip being not threadlocked (either from factory or from their own stupidity) and still not coming loose in flight.

MIND: I am NOT saying that you don't need threadlock, nor that it is only of minor importance!!!!!

What I am trying to say, is that threadlocking is neither extremely critical nor black magic, so if a blade grip is coming loose that normally pretty well stays put on its own, there is more to look for.
I have seen blade grip bearings run smooth under static load, but completely freeze when subject to centrifugal force, because static the balls stay in place but under centrifugal force the balls move to the side of the races, for example.

A Blade Grip retaining bolt, does NOT work loose from the centrifugal force, nor does it work loose from the leverage created by the lift of the blade. It can ONLY work loose from the oscillating movement due to cyclic control.
So whatever might be wrong with the bearing, chances are the cyclic movements are transferred tot either the blade grip retaining bolt or the feathering shaft, and hammering it loose. The only threadlock that can withstand that, will at the same time make it impossible to remove that bolt without damage.

So: check your bearings carefully....

As to thread locking: I have professionally never seen thread locking agent being applied to the hole, always to the bolt. This, because threadlock in a hole does not get spread as efficient through the threads, as threadlock applied to the bolt: you don't pour paint on your model, hold the brush still and move the model to and fro.....

Brgds, Bert

I have been checking it constantly now, and after about 7 flights both grips have stayed tight.

I'm also not running a washer between my inner blade grip bearing and the inner thrust bearing. It was ratcheting the grip when i had these washers in, and dont see how they are necessary.

Originally Posted by finguz

I have been checking it constantly now, and after about 7 flights both grips have stayed tight.

I'm also not running a washer between my inner blade grip bearing and the inner thrust bearing. It was ratcheting the grip when i had these washers in, and dont see how they are necessary.

Washers usually serve to spread the load over a bigger surface, OR they serve to provide some clearance on the ballrace that needs to run clear. Imagine a normal ball bearing lying on a flat surface (that is essentially the situation if a thrust bearing and a ball bearing are situated next to each other.
Now whichever one is turning, there will be always one of the ball races rubbing to the thrustplate. That is what the washer usually is for, to give clearance to the moving ballrace.
But if that washer was ratcheting your blade grip, than there's your answer as to why the grips came loose....
Most probably, it was either the wrong washer, or it was in the wrong location.

Brgds, Bert

Yeah those washers are important, its probably why your grips are coming off. It give the bearing something to run on, otherwise the outer race of the bearing pushes on the dampers and locks up.