HC3-SX Sensitive cyclic pitch control

[garyl]

I have a Vario scale heli with a 1840mm 2 blade rotor disk that is very sensitive in cyclic pitch, I have only 3 degrees of cyclic pitch with 60% expo. I don't have to move the stick much to make it move, the pitch is more sensitive than the roll.

Here is my setup
BLS451 servos, balls at 16mm from center.
Head gain 100%
cyclic ail elev gains 13
Agility 5
Initial response 5
Elevator filter 7
P 25
D 5
Attitude hold range 8
Decay rate 8

Anyone have any ideas why, could it be a servo resolution issue?

[F1 Rocket]

At first glance your Initial response is set very high. Lowering this to 1 or 2 will help. The Elevator filter is also very high. This parameter is used to tune out elevator bobbles but if set past 4 the elevator response will become very sluggish compared to the aileron.

I think there may be other issues with the setup. When you did the initial setup did you adjust the TX travels so that the sliders on the diagnose page were driven to the 100% marks? This is important to have right before you set the aileron/elevator travels on the mixer page. When you set these you want a fairly high amount (8-10 deg) of cyclic throw. This may sound like a lot for a scale machine but what you are setting here is the maximum amount of cyclic the system has available for use. Your actual cyclic rate will be set with the Agility slider on the Rigid page and or the D/R setting in the TX. Ideally when you set the travel in the Mixer page the amount should be between 60-80%. If it ends up much less than 60% your servo arms are too long. If it ends up over 90% your servo arms are too short.

Once you verify the above setup try these settings for the Rigid page

Aileron gain 14
Elevator gain 18
Agility 6
Initial response 2
Elevator filter 2
P-30
D-6
Attitude hold range 8
Decay rate 5

Reset the total head gain to 40% before you fly and increase it until the head starts to shake a bit. Then back it down 10%. If you get to 100% without head shake increase the aileron/elevator gains by 1 point each, back the total gain down a bit and try again.

Danny

[garyl]

Thanks for the great response!

I did the setup wizard and the diagnose tab was performed correctly. I did limit the cyclic pitch to 6 degrees so I will have to change that, I keep forgetting about the max cyclic pitch for the gyros to use. The collective pitch max is 11 degrees, its a heavy heli. I will make all the changes you stated and report back how it works out.

Thanks for your help!

[DEMONjoe]

And do not forget that after setup was completed, you are allowed to use Expo or even Dual Rate on elevator.

Regards,
Joachim

[garyl]

Originally Posted by Joachim HC

And do not forget that after setup was completed, you are allowed to use Expo or even Dual Rate on elevator.

Regards,
Joachim

Thats what I did, I dialed the cyclic pitch down to 3 degrees with 60% expo in D/R and it was still a little pitch sensitive. I plan on changing everything and test flying tomorrow, I will let you know how it works out.

Thanks for the support!

[DEMONjoe]

Btw: met some guys at the big scale meeting here in Germany last weekend, using up to 90% Expo and 50% DualRate Never seen something like this before. The mechanics must be horribly aggressive.

[popokatepetl]

Could you post your HC3 file?

[garyl]

Originally Posted by popokatepetl

Could you post your HC3 file?

this site will not upload the .hcx file.

Danny,

I reset everything and the settings you gave me settled it down a little, but now I have a tail bouncing up and down when I give it a quick input and center the stick. I increased the elevator filter slowly to 8 and the gain to 19 but it is still there.

[F1 Rocket]

Back the elevator filter down to 3 and increase the P-gain.

Danny

[F1 Rocket]

How is the CG o this machine? Does it hover with a level swashplate? Is the head dampening soft? If so can you fit stiffer dampeners? Sorry for all the questions. The more I know about the machine the more I can help.

Danny

[garyl]

Originally Posted by F1 Rocket

How is the CG o this machine? Does it hover with a level swashplate? Is the head dampening soft? If so can you fit stiffer dampeners? Sorry for all the questions. The more I know about the machine the more I can help.

Danny

The CG is slightly forward, the rear skids lift about 10mm before the front. The dampers are medium. It does hover rear nice now with a level swash, just the tail bobbing now. I will back the elev filter to 3 and try going up with the P portion.

Thanks.

The mechanics are the Vario benzin with electric conversion.

[garyl]

Danny, the P-portion is at 50 and the tail bouncing has been greatly reduced. Now I still have to test it in forward flight and see how it reacts but it is much much better now. I also added shims to the head to tighten it up.

Thanks for all your help!

[garyl]

Danny,

Works great in forward flight as well, you solved another one.

Thanks for all your help.

[F1 Rocket]

I'm happy to hear your machine is flying well. If the machine is still a bit sensitive you can reduce the Initial response some more. Have fun.

Danny

[DEMONjoe]

....and do not forget to bring this beauty to IRCHA. I would love to see it in real

[garyl]

Originally Posted by Joachim HC

....and do not forget to bring this beauty to IRCHA. I would love to see it in real

Thanks! I don't know if I will make it to IRCHA yet, something always comes up to mess those plans up.

[capesandblaster]

Saw this Cobra fly at NEHC's funfly. I didn't think it could fly any better!
Gary...your a perfectionist. (Thanks for your help, setting my hc3-sx up)
Adam

[garyl]

Originally Posted by capesandblaster

Saw this Cobra fly at NEHC's funfly. I didn't think it could fly any better!
Gary...your a perfectionist. (Thanks for your help, setting my hc3-sx up)
Adam

I had to really work hard to make it fly like it did and now it flies like it has cruise control. When you have been flying helicopters for over 30 years you can make a tird look like it flies good.