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Flybarless Helicopter Systems CSM Cyclock, Helitronix Multi-mixer, Spartan AP2000i, Firmtronix Digimix-3, Gyrobot, SK360and AC3X


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Old 07-26-2010, 05:12 PM   #1
Basmntdweller
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Default SJGD help

I am assisting a friend with his four bladed project heli. We have dealt with HeliCommand Rigid on previous 4 blade projects but thought we'd try the SJGD unit on this one, mostly due to cost of SJGD versus the HC.
I've got it all set up and it is flying but not very well. Our initial test was done with some plywood skids and basic pod and boom set up. It seemed to do fairly well in that configuration. We took the mechanics and installed them in a fiberglass fuse for final fitting and flight testing before putting the finish on the body.
In the body, it didn't fly well. Admittedly, fully rigged it tipped the scales at just over 20lbs versus the test rig at just under 11lbs. My biggest concern is the cyclic control. It will from time to time, "shudder" for a few seconds and then settle back down. It does this in both roll and elevator, not necessarily both together or separately. I am thinking this may be vibration getting to the sensor but not sure. Nothing on the heli shakes for the most part but it is so heavily built it can't shake. I have ran the gain as low as 10 on both aileron and elevator and as high as 60. 10-20 range is better but not drastically. It just shakes a bit more violently with the higher gain.
The tail is having issues as well but we are thinking that the tail disc just doesn't have sufficient authority to control the tail. We are going to hang a Gy401 on it just for a quick test as I am plenty familiar with them to know if we have a mechanical problem ( disc too small, blades too slow) or set-up issues with the SJGD.

FWIW, it is about 20lbs, 10S electric, four bladed head turning 710s about 1100 rpm. This is the most headspeed we can get out of these mechanics without changing motors or batteries. These are the same mechanics that fly just fine at 1100 HS with 800mm blades at 30lbs.

Any direction you might be able to provide is appreciated.
Thanks, Matt
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Old 07-27-2010, 01:30 AM   #2
Vinger
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The unit is the same as the Turnigy TBar 600, so you can dig into that thread as well. The shudder you mention is definately vibration related. Mount the unit on thick double sided tape and strap it down with a Velcro strap.

As for the tail, you definately would need more power from it, larger blades or increased tail rpm should do the trick. I don't know what mechanics you are using, but swinging 4X 800mm blades require a lot of torque and you have to counter that with enough power.
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