Odd Tail problem

[Dan MacKay]

Hi guys,

I have a CP that is hardly a CP anymore as I upgraded to the aluminium frame, boom and gear, three a HH Gyro on it, brushless, ESC and just put the all metal head from MicroHeli on. The head is awesome, easy to set up and as smooth as silk.

I just started encountering a bit of a problem today. I am loosing right tail control the more collective I add. The heli was flying hands off for about 10 minutes or so and then started turning left. I had to start adding more right input and a tad of collective. But as I added the collective I would loose all tail control alltogether. Thank heavens the heli is well balanced as I managed to save it quite easily the few times I tried it. It seems that a power, just into a hover, it would behave not too bad but the more collective the less right input I had to the point I would have none.

I only have one tail motor on this heli even though I have aluminum tail with room for two. I have never had a motor go like this so I was wondering if any of you might have experienced anything like this and if so is it worth putting the a second motor on?

Thanks,

Dan

[Danyboy]

Hello Dan,

Sounds quite interesting, your setup... :)

Question on the tailmotor: How old is it?
I found that after around 50 battery charges of fliying, the tail-trim-drift would get to a point where I would start as usual with trim halfway right but with flighttime was getting to the max left with trim and still needing more toward the end. Getting a new motor solved the problem, so it appears it was simply out of life...

Since it appears that your tail does not work so well with full voltage applied (full throttle), it is also nearing it's end...

Cheers,

Daniel

[Dan MacKay]

Hi Daniel,

Thanks for the response. I bought two new tail motors and installed them. This did not cure the problem and infact things are getting a little worse. Now the thing is having some difficulty getting off the ground, the tail is very unpredictable as well as I loose pretty well right input after just a minute or two of hovering and it seems to be cycling hi power/low power. I have a HH gyro that has been acting flawlessly on this unit so I do not think it is the culprit. I have the Blade 3 in 1 to control the tail in conjunction with the ESC so I am wondering if this might be the sign of an ESC going south. As I have not been in the sport long enough to have an ESC die does anyone have any experience with this?

Dan

[bluemooone]

:dontknow

[EdgeCrusher]

Sounds like the heart and soul of a blade cp is still with you :smokin:

[Dan MacKay]

Sigh, I guess so. I can hardly wait until I get the HDX 300 kit that I ordered yesterday. I would still like to get this bird up and running again.

[Danyboy]

Dan,

Sorry it didn't work out... :dontknow

Another thought I'd like to share with you.
What's the headspeed?
Could it be, that your headspeed is somewhat lower than stock?
That would result in more pitch for the same lift, which generates more torque.

As I read your text another time, it could simply be, that the tailmotor is at its maximum power, unable to deliver more...
That would happen if the Torque from the main rotor is considerably high and the HH-Gyro already uses full "servo-deflection" to keep the tail straight. Then you would have no deflection left to make it turn right (counter-mainrotor-wise ;) )...

So try "messing around" with headspeed (also if its higher than stock!).
If possible, try to get somewhere close to stock (because that's where the design is supposed to work) and work your way to the RPM you wish...

I hope this helps...

Cheers, Daniel

[Dan MacKay]

Hi Dan,

That could be it as I was messing with the pitch. I am pretty new to this and profess my ignorance. How do I change my head speed? I am using a Futaba 7CHP radio to control this critter. I am using 60% gain on the gyro settings in HH mode. I assume that by setting the head speed you mean adjust my pitch curve to be less aggressive as compared to the throttle curve. This all started happening when I changed to the all metal CNC head but I thought that by eye balling it I had it set up pretty close to the last set up. Previously I had it in a fairly hands off hover about a foot off the ground at 50% stick. After I set the new head up I required a fair bit more collective to get off the ground so it makes sense that if the pitch is too great for the throttle curve poored performance is achieved while generating too much torque for the tail. I will chech it out and see what happens. Once again claiming ingnorance is this the right way to adjust headspeed?

Thanks,

Dan

[Danyboy]

Dan,

Now here comes the part where "distance-healing" comes quite tricky...

The problem of torque is not only solved with either pitch or throttle-curve, but with both...
The way I would attack the problem:
If possible, I would recommend to increase RPM first.
You will notice you lift off earlier/with less throttle than before, so you can then lower the pitch in a second step. Then again, a bit more throttle, followed by pitch. I strongly recommend only to change one thing at a time, then test, then change the second things. Don't hurry, test thoroughly...
Out of the blue, I would recommend to close in on a target-setting where you can hover with around 75% throttle (talking about throw-setting, not stick position). If you have a symmetric pitch-curve, you might end up with the throttle-stick at 3/4-travel.
On the stock, you'll have 12° maximum pitch, since the brushless-setup should have more power, I would expect you'll end up with between 8 and 10° maximum pitch.

Have fun and happy hovering!

Cheers, Daniel

[Dan MacKay]

Hi Dan,

Thanks a lot for the help here. I certainly appreciate it. I think that my problems are far deeper than that i.e. electrical. I have a suspicion that the 3 in 1 controller may be heading south. This first started happening just after I installed a CNC head. But...I had it hovering nicely and then started to loss tail control. I thought that it might have been the tail motor so I just replaced it with two motors with not a lot of change in the problem as a matter of fact it was getting worse. So I changed back to the previous head, set it back up and took it out for a fly. It was just about the same. When I was trying to fly it the tail was very, very sensitive and I could hear the gyro trying to compensate (O% gain on the gyro itself and 30% on the radio which was my previous setup) so I can assume that it is working fine. Out of desperation I started mucking about with the proportional and with the pot totally CCW I get no tail what-so-ever and with any proportional I get max proportional on the tail pushing the tail left. I try and trim it out on the radio and with five clicks left I get little or no input. I have the same setup as the CP Pro Brushless. I do not think it is the ESC any more as the main motor pulls fine. The tail is pulsing and difficult to control. If I am not mistaken in this configuration the sole purpose of 3 in 1 in this configuration (other than to provide power) is to mix the tail rotor. Could this be the problem?

Dan

[carlo_the_wonder_frog]

Have you tried a different battery? Sometimes you might have a bad cell that loses its charge very quickly and sends the ESC into Low Voltage cutoff, Alot of ESC's pulse the motor to let you know its hitting the cutoff. I have no experience with the 3 in 1, just the 4 in 1. If I were losing tail I would look at the motor, obviously that isn't the problem, has the tail rotor come loose or spins on the shaft? Next look at the power source, then think frayed wire, loose connection, bad solder joint, last after its all verified good is the 3 in 1.

Changing the head speed on the Futaba 7chp is very easy. Turn on radio, make sure you are on correct model, mode ( PPM I assume) and have all the switches in the forward position. go into the programming menu and look for " TH-CV (N) ", select and you will see the following"

TH-CRV(N)
P5> 100.0%
P4> 75.0%
P3> 50.0%
P2> 25.0%
P1> 0.0%

"
TH-CRV(N) means Throttle Curve ( Normal)
Those numbers represent how much throttle should be given, relative to the collective position. P1 stands for point 1( Lowest collective), P5 is point 5(Highest collective) and so on.In other words at full collective you will be getting 100% throttle and at middle collective you will get 50% throttle and at no collective you will have 0% throttle. Change those % values to lower numbers will decrease the throttle hence reducing the headspeed. for example, if I wanted my headspeed reduced by 1/3 i would reduce the numbers by small amounts at a time until I reached the right head speed. Verify your headspeed with a tach, its the only way to really know how fast its spinning. Hope this helps.

CtWFrog

[zflarez]

Why would the headspeed matter if it is not a driven tail were the tail rpm is in direct porportion as the headspeed. With a motorized tail you could have full tail controll with 0 headspeed. The amount of torgue generated does not increase with less headspeed just the ability for the tail to counter gets harder when it is turning slower since less air is being moved.

[Dan MacKay]

Hi CtWFrog,

Thanks to all that helped here. It is amazing how much one can learn about a heli when trying to track down a problem. As it turns out it was a combination of two problems. First was when I examined the tail rotor shaft and bearing assembly I noticed the the shaft retaining collar had loosen up and that there was quite a bit of play in the shaft, enough if fact that the drive cog could actually move far enough away from the pinion gears on the two motors to just about lose contact with them. I suspect that at the higher rpm the cog would slip off the pinions which would explain part of the problem there would likely still be enough friction to keep the tail spinning but not enough for control. The second problem was definely the head speed. I moved it up to 65% at half stick and I am back to a hands off hover at three feet off the ground. Other than the tail rotor shaft being loose I guess the big lesson it learned it that after any major change such as changing a head that you set up is not going to be identical to what it was the last time.

Thanks for the help.

Dan