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HelicopterFlybarless Rotor Head SystemsFutaba CGY › H4-45 Swash type and severe servo binding
10-22-2015 02:23 AM  26 months agoPost 1
ssmith512

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Indianapolis, IN USA

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I am having some severe servo binding issues on my model using a 4 servo, H4-45 swash type. No binding at zero pitch collective, binding increases as collective is increased.

Made a vid to explain my issue. I am completely lost on how to solve it. BTW, not mentioned in the vid, swash phasing is set to 45deg, that is what the swash moves in "funny" directions when I apply ail or elev. Thanks in advance!!!

Watch at YouTube

Steve

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10-22-2015 04:05 AM  26 months agoPost 2
Dr.Ben

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Richmond, VA, USA

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A lot of what I see is caused by 4 servo eccpm being intolerant of the inherent interactions that occur when the sws rate % is pushed as high as you have it. Direct link systems are the worst for this, and four servo set ups bind up the system worst because the extra link blocks the swash from being able to interact to absorb the differential throw disparity caused by some servos in the quartet being throw further off centerline while others approach centerline. In the old days comparatively crappy analog servos where preferable on these models because they halfway tolerated being placed in a bind as compared to digital servos. The reason 4 servo eccpm is so infrequently used these days is because the moment ANY cyclic input is introduced with any noticeable amount of collective pitch, the system is immediately placed in a bind. In your case you need to look at every aspect of that model's control system and try to find some more mechanical cyclic rate while getting the sws rate percentage down closer to 50-60%. As a scale model it will fly fine with as little as 8 degrees of cyclic. You also need to read up on the linkage compensation menus because they help to palliate the effects of the differential travel and reduce the binding.

Try that.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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10-22-2015 01:18 PM  26 months agoPost 3
ssmith512

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Indianapolis, IN USA

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Thank you very much for the explanation and suggested solutions. I do appreciate the help!
In your case you need to look at every aspect of that model's control system and try to find some more mechanical cyclic rate while getting the sws rate percentage down closer to 50-60%
If I understand correctly, I can accomplish this by increasing servo arm length and/or decreasing ball distance from center on the swash plate? I am able to either very easily on this model.
You also need to read up on the linkage compensation menus because they help to palliate the effects of the differential travel and reduce the binding.
Will do. I played around a little bit with swash mixes many many many moons ago once on a flybar model and my trusty 'ole 12FGH, but I have replaced those memories with grey hair unfortunately! LOL! Must spend some time and get a refresher course.

Steve

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10-23-2015 02:45 AM  26 months agoPost 4
ssmith512

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Indianapolis, IN USA

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Well, could never get all the binding out. Had to max out most of the adjustments and still had binding and ended up chasing my tail a bit. As a last ditch effort, I decided to get rid of the 45 degree phasing by modifying the rotor head for 0 degree phasing (head is manufactured for 45 degree offset, but some simple pitch arm extensions gets me 0 degree offset). With AIL and ELEV RATE percentage at 50%, I have 9 degrees of cyclic, swash ring at 100% and with just a tiny bit of compensation adjustment at full collective, I get no binding. I am finally a happy camper.

Thank you Dr. Ben for the help. I learned quite a bit reading up on all of the compensations available in the CGY750.

Steve

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10-23-2015 05:30 AM  26 months agoPost 5
Dr.Ben

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Richmond, VA, USA

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Those are good numbers Steve. Glad you did it as you did, because based on our previous discussions before these past few days, the original geometry was a fustercluck.

Ben

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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10-23-2015 01:48 PM  26 months agoPost 6
ssmith512

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Indianapolis, IN USA

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the original geometry was a fustercluck.
I'd say that is putting it nicely LOL!!

Thanks again for the help and prodding me in the right direction.

Steve

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HelicopterFlybarless Rotor Head SystemsFutaba CGY › H4-45 Swash type and severe servo binding
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