Help Please!!! My Ups & Downs with Micro Heli Flying

[IML2860]

Hi All,

Newbie to this forum & micro heli here & I hope you can help me to identify my problem with the Zoom. I am running with the stock 400 motor with a 3C Lipo 1200 battery. After 3 trimming flights in the past three days, my Zoom hovered with extreme stability as late as yesterday afternoon. After this last flight, I recharged my Lipo and went for another hover session about 3 hours later.

While one would assume an uneventful flight, this is not what happened -- At first, I was having problem maintaining a hover. I then started to notice some vibration that I've not seen before. Two minutes into the session, the Zoom started to pirouette left as soon as it is 3 feet off the ground. Full right yaw does nothing even if I can clearly see the servo moved.

What could be the cause of the vibration??? I checked the main and tail rotor shafts and they are both ok. Would it be the 400 motor burning out???

Why would it pirouette left just like my Piccolo with a burned out tail motor???

My throttle curve is 0/40/80/90/100% and my pitch curve is 30/60/70/80/90% with +10&-7& degree pitch (which makes the curve -2/+3/+5/+6.5/+8 degree). Is this pitch curve too much load for the 400 motor???

While it is a perfect excuse to upgrade to a brushless setup, I really want to find out why it flies so well one hour and behaves just like my Piccolo the next. Your suggestions are very much appreciated.


Best Regards,
Henry

[mailee]

Check the pinion on the tail rotor shaft it could be coming loose which would cause the problem.

[IML2860]

Problem Solved!!!! The vibration turned out to be a slightly bent spindel shaft - everything is a.o.k. once this shaft is replaced. As to the cause of lossing tail control, it turned out to be caused by an agressive Pitch Curve. Once I lowered it to 40/60/65/70/75% on +10/-7degree pitch, there is no more drop in head speed when collective goes up and the tail is rock solid again. :lol:

Thanks for your input.

Henry

[Hotshot Charlie]

Good input Henry! Thanks for the info. I think I will tone down my pitch cures also and see how that works.

[rob_jones]

I have found that the Zoom really likes a high head speed with very little pitch. Mine is only pulling about 6 degress at full positive, and about 2.5 degrees in a hover. The head speed is higher than my tach will read - it goes up to 2100.

Even with so little pitch, it still climbs like a monkey on crack. And it still will bog a little in a full power climb, so I may try 5.5 degrees and see how it works. I have noticed considerably less left and right yaw when climbing and descending with the lower pitch settings.

[IML2860]

I think we can all agree that high head speed and less pitch is the way to go with the Zoom. I have changed my pitch from +10/-7 to +7/-3 and the Heli flies extremely well even with the stock 400 motor.

Moving on to a different topic, do you have any feedback on the new Ultem gears. My stock tail output gear already have 3 shorten teeth on it after 7 flights. The time for an upgrade is imminent and I want to know if I should head straight for a bell drive conversion (just hate taking the frame apart) or the ultem gear.

Henry

[rob_jones]

Henry,

The belt drive is a bit more invloved than just taking the frames apart. But it does solve the gear problem permanently.

HotShot Charlie has been flying the Ultem gears and seems to really like them. That would be a cheaper and easier fix. I also hear that there will be a factory upgrade that includes bevel gears. That still won't solve the problem of the input gear, though. And that's the one I had the most trouble with... :arggg:

[Hotshot Charlie]

The Ultem is hard, it ate up my "purple" spur gear on my tail drive shaft. yesterday. I might not have had the gears set right, but I figure I will put the brass spur gear on the drive shaft and this won't happen. I don't think the brass will eat up the Ultem or vise-versa. We will see. I will include a photo of the damage.

http://www.helifreak.com/album_mod/upload/41096d265d466e87902ba96887f9860f.jpg

You will also notice that my gear is installed backwards, because I am using the HiMax motor and I don't have enough shaft to reach the top teeth of the TR input gear.... so I had to set it up backwards.... so to speak.

[rob_jones]

Don't ya just love how solving one problems causes another? It looks like the mesh is a little tight, but I don't see how you could adjust it. Going back to the brass gear may be the answer. Let us know how it works out.

[Hotshot Charlie]

heheheeh.... you gotta love it. I could probably sand off some of the inner part of the gear, but don't know.... that would be the only way to give it more space.

ARE WE HAVING FUN YET ???

[Pipefish]

Hey Curly ,

I think you gotta put you CNC to make a spur gear with Ultem.

What about it huh?

[Hotshot Charlie]

Yes, Curlyq could help us put on this gear also????