TB and Tail Drift breakdown

[LowFlyer]

Out of the box my CX2 hovered pretty well except for some tail drift that was impossible to dial out. I think a combo of voltage drop and heat are to blame for this. I tested the gyro by twitching the tail and noted the motor's RPM change in each direction.

I chipped a blade and after changing them I suffered from the TB swirl. I found the CG to be within 1mm out of 20 blades tested so I stopped checking this, but the weight difference was significant. Balancing the blades was a huge improvement. My fly-bar was also off balance so I balanced that also. I haven't crashed or landed hard, but still verified nothing was bent or assembled wrong by dissembling/assembling. I found the top bearing was not centered in its holder so I upgraded to aluminum. I did not like the slop in the stock swash plate so that went to.
I found blade tracking easy to do with a whitewall in the background and at a distance of three feet.

I was now flying well except for tail-drift. It was annoying in tight spaces like the house, but in a school gym not a problem.

During the 19th flight my CX2 suddenly lost control in the rudder axis. The hover was stable, but no rudder. Testing revealed The gyro was not responding. I borrowed a 3in1 to verify and the model flew better then first out of the box.
The 3in1 is on its way for repair/replacement.

My experience so-far leaves me with the following thoughts:

> Blade balancing is very important.
> Blade tracking a must.
> Minimize vibration through proper assembly and verifying straight components.
> Adjust swash plate for neutral control.

The CX2 design is pretty simple, and mechanically sound. The big difference in performance with two different 3in1 units has me questioning its quality. Could the 3in1 be the source of tail-drift? Is there a known problem with the units?

I really like this heli, but concerned that the tail-drift will keep me from accurate indoor flying. Is there hope?

[JukeBoxGuy]

You can adjust the proportional mix using the front pot on the 3-in-1, but ultimately, there will always be some tail drift as the battery runs down.

I've trimmed my CX2 so it's optimal about half-way through a charge. That way it sort of grows into it's trim and grows out again as the battery drains. Adjusting for the drift has become automatic for me, so I've just accepted it as a characteristic of this type of heli (co-axial). I fly in and out of tight places all the time.

[hawkman]

Thats an outstanding post LowFlyer

Yes those points are important, you can be lazy and ignore...and struggle to fly...or by going through those stages of setting up you will get a heli that almost flys itself.

I like the CX2, I own a similar heli that uses the same parts. For what you pay for they are the best of that price band.

I have flown the fixed pitch helis that have a tail rotor motor, hard to fly and I just dont see the point...you will get more airtime with the CX2 for sure.

I like the fact you have gone for precision and thats right...you will get more joy out of a heli thats nicely setup and adjusted.

Will you ever go for a collective pitch/driven tail rotor design one day?

I got myself a Trex 450 XL this year, what a total bargain this heli has been...you get to build it yourself...some parts are preassembled but it pays to check them. I live in a breezy part of the world...theres not many days where I cant fly the Trex. Its a gem of a heli.

Rob

[LowFlyer]

Thanks JukeBoxGuy for confirming that drift does exist and is something that can't be totally tuned out. I was going crazy trying to achieve hands-off hover ( somewhat). Glad to hear you are having success with you model!

[LowFlyer]

thanks hawkman for your reply. I am a technical person who gets equal satisfaction out of maintaining RC craft compared to piloting. I enjoy heli engineering and the complexity of these flying machines.
I am new to heli flight and will need a lot of practice, but proper setup is coming natural for me. I spend a lot of time studying heli theory.

I would love to be able to fly a CP machine to its full ability, but that will be a while for me. Glad to hear you are having success with your Trex. I haven't crashed my CX2 yet so I am gaining confidence. I use to be build custom RC boats and cars, but once I experienced the offerings of flight, ground machines seem boring!

Heli machines are now in the reach of more enthusiasts then ever before. I regret not being able to get into it sooner. The sophistication and complexity of helis will keep me interested for a lifetime.

Good luck with your Trex. It does look like an awesome machine! I agree with your thoughts about FP helis. I believe most enthusiasts would be happier transitioning to CP, but if I could afford it I would take one of each please. I hope to someday be able to post about my success with a CP heli!

Good Luck!

[hawkman]

CP is much better, FP needs more anticipation in the hover...CP needs some consideration during transit from hover to forward flight and vice versa.

I am not fussed about doing stunt flying...more interested in camera work really.

I have found that if you are careful with these helis...and fly within your limits..though its good to push the boundary a little bit then rc helis tend to last a long time.

The Trex offers a lot for its size and money...its the serious radio that is the single biggest expense.

Rob

[LowFlyer]

Hawkman, it is refreshing to learn that you fly your rig on the conservative side and with a specific purpose. I think aerial photography adds a whole new dimension to the sport that has professional applications. Maybe you can use your talents to inspect high structures for defects.

I am an electronic designer that enjoys building hobby circuits. I have published a few articles in Nuts & Volts about hobby circuits. I plan to experiment with devices that would be useful for helis, but it will be difficult to keep the weight to a minimum. Telemetry and video could be exploited very well using helis.

If I continue to have trouble with my 3in1 I may attempt to use separate devices or build my own. I think there may be commercial provisions/plans for a discrete gyro for the CX2.

Do you have any aerial photos you can share? I am sure a website showcasing your photos would be popular.