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Monday, July 6, 2009

Ptitsa - My HBK2 Reincarnation


Hi there, looks like I have 2 parallel RC Helicopter stories going on .. both are very interesting stories, at least for me. :) So here is Ptitsa[1] story.

I was having problem with one of the new purchased Hitec HS-55 servo. The solution was, brought it back at the shop where I bought it, RcSmart ( After satisfied with my explanation and tested himself, the sales person replaced the malfunction servo with a new one. I also bought new plastic linkage for Ptitsa and a gallon of Nitro fuel (15% helicopter type) for Torii.

At the night, I put up the new servo, then I readjust the servo centering for all of the servo as well. I discovered that the plastic which holding the swashplate from rotating was touching with the new bell mixer assembly. I need to force bent it with my hand to make it clear from the rotating path of that piece.

Next morning (Wednesday), I was planning to try it out. With everything setup, I started to increase the throttle. Unfortunately, the motor seems refuse to rotate. When I tried to rotate it manually with my hand, I can just do it one way only. Puzzled with the situation I keep wondering, was the motor damaged or the main gear or the new head assembly stuck somehow. I keep trying a few more times, till the motor rotated for about one second and stop. This time looks like the motor has stuck for good, both ways!

At the night, I unscrewed the motor, took it out from the frame and try to troubleshoot again. Hoping for the best (motor can still be used, please), I keep trying this and that. After I knocked the motor gently a few times onto my house floor, I was able to rotate it with my hand. After a while of trying, I noticed there was something inside the motor. I took it out, it was something like a small washer, which I think had fell into the motor without me noticing. With that small-unnoticed-which-has-made-me-wondering-for-whole-day-thing outside of the motor, I have the motor running as normal!! Alhamdulillah. I am using out runned 3800kv motor[2] which is quite expensive to be replaced and thank god, I don't have to replace it!

Saturday morning (4-July-2009), I was really waiting for the moment so see my HBK2 Ptitsa flying again. It has been quite sometimes and it has been lots of new parts put into Ptitsa, I need to see it flying! At the night before, I was thinking, I can't risk Ptitsa crashing again. The control seems to be very erattic, how am I going to control it? Furthermore the controls are not yet calibrated to its center. After a lots of thinking I have decided that I need to put away my ego and back to the basic!! "Better safe than sorry" words also applied here. I decided to be back with the trainer[3]. Yes, I still have the trainer set I used about 11 month ago.. hmm that was already almost a year!

Ok. So, I put the trainer on. Brought Ptitsa to the front of my house.

I started to increase the throttle, the main rotor spin as expected. Lifted off successful. I was focusing very hard to maintain Ptitsa in hover, and I can't get it hovering at same place in stable way, and the vertical movement was very erratic. Ptitsa was very wild, she just want to fly everywhere, controlling Ptitsa was very difficult!! The tail was not really holding at same direction too, it tend to rotate clockwise. I ended the session after a few tries, need to think how to proceed with this.

Saturday night, I was at my in law house. The house have sufficient space for me to test Ptitsa.

I have configured the controller to put some EXP and DUALRATE% for the controls. After lots of thinking I started to notice that Ptitsa wild movement could very likely due to high head speed. I remembered that the last time I flew the HBK2 properly, I was using its original Radio Controller and it was in "normal mode". I reduced the head speed[4] and the response was much better. Ptitsa was not that wild anymore. Yes, Ptitsa is back, its flying!!

I still have to put lots of focus to put Ptitsa into stable hover. Ptitsa is very light compared to Torii, any slight movement it will accelerate very fast in that particular direction, so the counter control need to be fast as well. After a few short hovers, I started to get used to control rate needed and feel more comfortable. Currently I still flying Ptitsa with the trainer gear. I still need fine tune Ptitsa bit more, tail is still rotating/drifting clockwise.

Hmmm.. huh, there is one more unknown! I noticed after a stable hover for about 30 seconds, Ptitsa suddenly rotate counter-clockwise 90 degrees. I was quite panic when that happened for the first time! It seems that there is a sudden head speed increased. I'll have to check and confirm the problem and find the solution.

That's all for a now.


[1] Ptitsa is my Remote Radio Controlled Helicopter, it is a Honey Bee King 2 with upgraded swashplate and motor. I just recently put new metal rotor head into it.
[2] Honey Bee King 3 come standard with 3000kv motor, my Honey Bee King 2 standard motor was even lower. So this is really a very good finding for me.
[3] Helicopter Trainer is 4 ping pong ball attached to 4 rods, attached to the helicopter skid to make it harder to tilt, normally used by beginner in first few days (or weeks) in learning to fly RC Helicopter.
[4] Head speed is reduced at the throttle pitch configuration, at this moment I have 100% as 65%, 50% as 45%


Torii Test Flight - Passed


[This event happened between 25 Jun to 28 Jun 2009]

Alhamdulillah, from the previous short test flight, Torii[1] was able to fly without any problem. However I felt the flight characteristic was very different. The rate of climb was very low, and the head speed seems to be slower than normal.

On last Sunday evening, about 6.30pm, I brought Torii to Putra Heights Flying Field 2. It was already quite late and I don't have much time to spend for the flying session. I had checked Torii's blade pitch at the earlier night to ensure that the slow climb rate and slow head speed is not due to that.

When I reached the field, I quickly prepared Torii for the flight. This time, I opened up the canopy to check the screws. Need to make sure all the screws are not loose.

This is the lesson learn from Torii's last hard landing. After satisfied with the condition. I tried to start the engine. The engine was harder to start this time. I got it hydro-lock-ed once, and need to rectify it by opening the glow plug and run the starter a few times without it. I managed to get the engine started, after I moved up the throttle a bit. This was the first time I need to do this during the starting up of the engine. I was wondering why was it so.

Proceeding with the test flight, I carried Torri 10 m to a clear area at the field for the take off. After completed control check on the ground, Torii lifted off successfully without any problem. Another quick check on the controls during hover confirmed that the controls are ok. Tested with normal figure 8 flight. I noticed that there was lots of smoke came out from the muffler. Landed the Torri, then checked the engined temperature and turn the High Speed Needle (HSN) at it OS 50 Hyper Engine to make the mixture leaner. Lifted off again to continue with the testing. This time the flight was much better and Torri has its normal climb rate back!

Continue with figure 8 flights, till the main tank almost empty. I taxi[2] Torii to the normal landing spot, among the trees.

Yes. Successful test flight for Torii.

In conclusion, the slow response in flight and low climb rate for Torri was due to rich mixing of fuel.


1. Torii is my Remote Radio Control Helicopter, its a Century Raven 50 CCPM
2. Taxi for Helicopter is to fly slowly at low altitude, normally to the exact landing spot or exact cleared take off spot.


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