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HomeRC & Power✈️Aircraft🚁HelicopterFlybarless Rotor Head SystemsOther › Cyclic Gain and mechanical mixing
09-15-2009 10:31 AM  11 years ago
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ehaga

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Bærum, Norway

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Cyclic Gain and mechanical mixing
Hi,

I tries to calculate to find the correct values of Cyclic Gain for a V-bar on a Hirobo Evo 90.

Will the "Calculator CG" be the same for all mechanical mixing helis ?

Regards

- Erik -
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09-15-2009 12:07 PM  11 years ago
Chuckie (RIP)

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Crofton Maryland

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No it depends on the dimensions of the swash and the relationships of the servo arms, bell cranks, or control mechanisms to the swash.Please stand by for faster service!
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09-15-2009 01:51 PM  11 years ago
ehaga

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I mean : Can I use http://www.graf-eckstein.de/heli/vstabi/cge.php to calculate CG on a mechanical mixed heli.
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09-15-2009 02:02 PM  11 years ago
puma1824

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Maryland, USA

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I mean : Can I use http://www.graf-eckstein.de/heli/vstabi/cge.php to calculate CG on a mechanical mixed heli.
No. On a mechanically mixed (mCCPM) heli you do NOT use the Geometry tool. According to VStabi support:

"Cyclic Gain has to be set higher (Use Default for H1), because the Throws are not shared between collective and cyclics. Collective setting also may be increased as you like."

On a mCCPM Raptor 90 / R50 Mikado guys "came back to CG about 100..110 instead of 156" -156 being the default for H-1 (mCCPM) setups.

and more from VStabi...

"100-110 seemed better or so I understand.

As far as I understand, in m-ccpm there is no interaction, so Pitch is output directly to 1 Servo, and CG is output to the other 2 Servos.
So CG is a factor at the end of the control loop, scaling the output value of the control loop.

I would say if the servo throws are within a sensible range (e.g. +/– 30-40°), it's OK to use CG to adapt the servo output.

So, the 100-110 could mean that on R50/90 that was what they found out (instead of 156 what was found earlier on, maybe on an other H1 heli)."

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09-15-2009 08:54 PM  11 years ago
ehaga

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Hi again,

Thanks for the answeer. But could somebody tell me what happens if you set Cyclic Gain to high.

Regards

- Erik -
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09-16-2009 05:47 PM  11 years ago
MrMel

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Gotland

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cyclic gain (under Setup->Swash->Expert) is a poor translation really.

cyclic throw output would be better, or cyclic throw limit

It's just a value that controls how much physical output the system is putting on the cyclic.
The higher value, the more movement on the servo.

(has nothing to do with "gain" in terms of gyro)
Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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09-16-2009 07:16 PM  11 years ago
puma1824

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cyclic gain (under Setup->Swash->Expert) is a poor translation really.

cyclic throw output would be better, or cyclic throw limit

It's just a value that controls how much physical output the system is putting on the cyclic.
The higher value, the more movement on the servo.
So under these circumstances, without the ability to use the Geometry tool, you should set the number to give you a certain cyclic pitch angle? What should the target cyclic pitch be set to OR should it just be the max number before binding?
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09-16-2009 07:46 PM  11 years ago
MrMel

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I aim for 10-11 degrees cyclic pitch for 3D flight.Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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09-17-2009 08:10 PM  11 years ago
Chuckie (RIP)

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Crofton Maryland

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Cyclic Ring has an affect on the amount of cyclic throw on the blades so limiting cyclic gain to only give 10-11 degrees of cyclic pitch is not the right way of using the parameter. Test it for your self. Change cyclic ring while holding full stick and watch the blade angle change. If your heli due to the mechanical design can use a high value of cyclic ring then you would limit cyclic pitch with another parameter? The cyclic gain setting has to be tested in flight. Too much cyclic gain and the heli responds too fast, if the gain is too low its responds a bit slower. Limiting the total travel of cyclic pitch will reduce the vbars ability to respond in high winds or demanding conditions.Please stand by for faster service!
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09-17-2009 08:20 PM  11 years ago
MrMel

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Cyclic Ring has an affect on the amount of cyclic throw on the blades so limiting cyclic gain to only give 10-11 degrees of cyclic pitch is not the right way of using the parameter. Test it for your self. Change cyclic ring while holding full stick and watch the blade angle change. If your heli due to the mechanical design can use a high value of cyclic ring then you would limit cyclic pitch with another parameter? The cyclic gain setting has to be tested in flight. Too much cyclic gain and the heli responds too fast, if the gain is too low its responds a bit slower. Limiting the total travel of cyclic pitch will reduce the vbars ability to respond in high winds or demanding conditions.
Should perhaps have written +-10-11 degrees which I meant, and thats about max you should have, more and its too much and you get poor resolution since very little movement on the servo render tremendous movement on the head.

For this, cyclic gain under Setup->Swash->Expert is the value to change.
Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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09-17-2009 08:34 PM  11 years ago
Chuckie (RIP)

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Crofton Maryland

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I understand what you mean, +-10 to +-11. I still think it limits the vbars control over the heli. When you adjust cyclic gain the relationship of collective versus cyclic changes in the software. Hence the tool provided by Mikado was to get the proper balance, or match the Logo 600 design.Please stand by for faster service!
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09-17-2009 08:41 PM  11 years ago
MrMel

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Gotland

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The calculation tool is there to see if your values are within acceptable range.

Cyclic gain is there to finetune, a heli with +-13 degrees cyclic pitch wont fly good, +-10-11 is more then enough (blades stall at 17-18 total pitch)

Acceptable range of cyclic gain is 80-110, it will fly with 70-80 ok, below 60 you get serious issues.

If you go below +-10, lets say +-8 and fly 3D you can experience what's best called cyclic blowout, its not fun, Ive tried.

For most helis there is a change to change, but everything is a tradeoff, you can move links on servo's inwards, which helps, but it dont make a perfect heli.
For a perfect setup you need to get the relationship all the way, from servo -> head.

Today's "hot" heli's have high ratio output, manufacturers rely on you buying good servos, you feel more "connected" to the heli, and you get faster cyclic.
However, that high ratio isnt really good for converting to flybarless.
Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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09-17-2009 08:49 PM  11 years ago
Chuckie (RIP)

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I follow what you are saying. My modified N9 with 1:1 bell cranks is setup close to the logo 600 mechanical ratio and has the calculated cyclic gain of 97, probably due to the size of the swash. The cyclic pitch with the cyclic ring at 80 is +-15 degrees. It flys great. What does the heli do when it flys poorly in your experience?Please stand by for faster service!
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09-17-2009 09:00 PM  11 years ago
MrMel

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double sided answer;

either it flies fine, but your servo has to work more then needed.
Not saying their not up to the task, but I logged currentdraw on various changes (balls on servohorn, balls on swash, widen the head etc), all makes up to differnt load on the servo.

or it dont fly as good as it can, just because the issue above, you get occational shudder on hard cyclic movement, just like the gain is too high, so you lower the main rotor gain to counteract.

Now it flies fine, but Instead you could have run more mechanical leverage, (lower cyclic pitch at same number) and you could have raised the gyro gain for the main rotor, and it would have flown more locked in.

Its all an balance.
Most likely you wont have much of an issue on the N9 since you have good ratio Servo->Bellcrank, its the swash that's the reason, but if you for say changed swash, the servo's would have even more mechanical leverage, and therefor work less, and you dont need +-15 for sure.
Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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09-18-2009 05:35 AM  11 years ago
puma1824

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Maryland, USA

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So when I setup a mCCPM machine what steps should I take to get geometry correct? Remember, according to Mikado support can't use the setup tool.

Should I start with the normal servo horn positions and work on extending the blade grip control arms and/or shortening swash balls for +/- 11 or 12 degrees of pitch at 80 Collective Common...like the eCCPM setups. Then work on the Cyclic Gain by:

1. MrMel methiod: while keeping CC @ 80, find value of CG for max 10-11 degrees of cyclic pitch. Raise cyclic ring until binds???

or

2. Chuckie method: Start tuning by flying and feel. Raise cyclic ring until binds???

I have my thoughts / view, just like to get everyone else's opinion.
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09-18-2009 05:50 AM  11 years ago
MrMel

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Gotland

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Adjust cyclic gain on bench to get valid deflection range (if its within ok values, else change mechanically), Agility slider to get right roll/fliprate (adjust in flight)Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more
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