Meh... not digging it so far... but it's getting better.

[9sec240]

I am pretty confident the tail jerking is a vibration issue. In this video, I am running 30% gain on gear end points (which is pretty low). I start out in F0 (0-70-75 throttle curve) and you can see the tail is jerking pretty hard and is consistently turning clockwise. I click up to F1 (80-70-80 throttle curve) and the jerking is reduced and the clockwise rotation stops. Finally F2 (straight 80% throttle curve) and the jerking is all but gone. Working my way back down the flight modes, the jerking and then the rotation come back.

With the main blades weighing the same and having nearly identical CG, the issue is likely in the tail or imbalance in the motor. I guess those are next in line to be inspected.

[ame]http://www.youtube.com/watch?v=m_WpUKb9vfQ[/ame]

[9sec240]

The vibrations I am getting are from the motor. It is horribly out of balance. I moved the motor away from the main gear so it was the only thing turning on the whole helicopter. Spooling it up just a quarter throttle was enough to vibrate the heli around the table. It smoothed out a bit at higher speeds.


[ame]http://www.youtube.com/watch?v=A65gIZzp9bk[/ame]

[Drivinfast247]

Originally Posted by 9sec240

The vibrations I am getting are from the motor. It is horribly out of balance. I moved the motor away from the main gear so it was the only thing turning on the whole helicopter. Spooling it up just a quarter throttle was enough to vibrate the heli around the table. It smoothed out a bit at higher speeds.


http://www.youtube.com/watch?v=A65gIZzp9bk

That cant be good!

[9sec240]

Pulled the bell off and you can clearly see the magnets are not spaced evenly. I used digital calipers to measure the space between the magnets and got:

6.70 mm
6.35 mm
6.08 mm
6.14 mm
5.47 mm
6.40 mm

The spacing is horrible and I am sure causing the imbalance of the motor.

Green line is from center of magnet to center of shaft. You can see it is not a straight line.

[InFocus]

interesting find. Maybe give HH support a call. I wonder if they would arrange a motor swap if they are interested in seeing this motor?

[9sec240]

I opened a support ticket. They have always been good with sorting out issues for me. Hopefully I hear from them soon and they send me a good replacement motor.

[honkytown]

Originally Posted by 9sec240

I opened a support ticket. They have always been good with sorting out issues for me. Hopefully I hear from them soon and they send me a good replacement motor.

good find, will look at mine too. just another question have you flown your helo yet or just doing R&D until now?

[9sec240]

I think I am about 8 or 10 flights in now.

[honkytown]

Originally Posted by 9sec240

I think I am about 8 or 10 flights in now.

that's good to hear i had a first look on my motor magnets, it ain't easy to measure the distance between them, but i can clearly confirm they aren't even on mine! i guess up to ~.8mm difference

[Hubschrauberpilot]

Any suggestions for a better aftermarket Motor ?

The Scorpion HKII-2208-24 only has 3590kv

I have a hunch my motor is also causing bad vibrations at higher speed.

[9sec240]

I looked at that last night. It is 2 mm larger in diameter which would likely require some trimming of the frame up top to get it to fit. Larger diameter also means it is closer to the link that is getting ground on stock motor. Then there is the added height of the Scorpion motor (+2.3 mm) complicating things too. While the kv is lower, an 11T pinion would sort that out and would position the motor a little further away from the main gear helping the link to motor clearance issue. I wish I had one handy that I could test. I can't find one in stock.

[JustPlaneChris]

What about a JustGoFly 400DH? I used to fly them in the Honey Bee King (same basic size heli) and it's a great motor:

http://www.justgofly.com/tech400dh.htm

I have one here, I can measure it if needed.

[9sec240]

I might have one of those motors actually. Looks just like that IIRC. I got it with some HBKII parts I got. I also have several Gaui 200 motors that would likely fit but might be underpowered.

I did find the Scorpion motor in stock at Innov8tive so I ordered one up. If it doesn't fit, I will put it in my Gaui 255.

[ahahn]

If you are really ambitious, you can soak the magnet bell in acetone and remove the magnets. Now space them back better.

Did that one time with a 10 magnet motor. This motor should be easier with only 6 magnets. I've used both a rubberized CyA and JB weld to glue magnets in.

[Dylwad]

Originally Posted by JustPlaneChris

What about a JustGoFly 400DH? I used to fly them in the Honey Bee King (same basic size heli) and it's a great motor:

http://www.justgofly.com/tech400dh.htm

I have one here, I can measure it if needed.

Wow what a horrible website!

4000KV might do well with an 11 or 12 tooth, would solve the link rubbing issue.

Its roughly the same size/weight as the stock motor.

Dylan

[JustPlaneChris]

Yes, horrible website. Good guy to deal with though and excellent motors.
I will be adding a 300X to my fleet within the next few weeks, I'll give that motor a try if I have time.

[Hubschrauberpilot]

Originally Posted by 9sec240

I did find the Scorpion motor in stock at Innov8tive so I ordered one up.

Looking forward your report.

[9sec240]

Horizon emailed back. They are sending me a new motor. Hopefully the new one does not vibrate like the original.

[9sec240]

Originally Posted by JustPlaneChris

What about a JustGoFly 400DH? I used to fly them in the Honey Bee King (same basic size heli) and it's a great motor:

http://www.justgofly.com/tech400dh.htm

I have one here, I can measure it if needed.

Memory does not serve me right. Here is a collection of motors I have in roughly that size. None of them look like that 400DH.

From left to right. The motor I thought was the 400DH, stock 300 X motor, mystery motor 2, Gaui 3800kv motor from Gaui 200, Align BL250SP

[JustPlaneChris]

Ah yes, that one on the left is one of the motors Helidirect used to sell I think... HDX maybe?
The JGF 400DH I have is 43.7g, ~25mm in diameter and about the same height. It has a stepped shaft, 2.5mm at the end but 3mm inside the motor.