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Servo set-up for correct geometry

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Old 01-06-2009, 12:29 PM
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scoeroo
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Default Servo set-up for correct geometry

OMP,

In the not so descriptive CD that comes with the new EDGE 540 80" ARF's , there is no descripition on how to set up the rear servos.

The pic's on the CD show an entirly different set-up.

The only way the servo's mount on these new model ARF's does not give correct geometry .

What is the big secret ?
Old 01-06-2009, 01:31 PM
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AFSalmon
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Default RE: Servo set-up for correct geometry

I agree, the manual stinks! We used the manual for the previous version of the ARF which has a different layout. I have updated the manual quite a bit and the new version is located online:

http://www.ohiomodelplanes.com/manua...arf/80edge.pdf

I still need to add some good pics of the new servo installation but I'm waiting on servos to install. Might have them today. But I'll try to explain. First take a dremel with a rotozip bit and cut slots in the hardwood servo supports inside the openings to clear the servo wire grommets on your servos. Servo wires face forward on all three servos. test fit your servos to check for clearance. You can cut the wood all the way through into the tunnel area (about 1/4" thick) if you want. The left elevator servo and rudder servo face the left side of the fuse in the lower double servo mount. The right elevator servo faces right and is installed in the upper servo mount. I hope this helps out and I'll get pictures up asap. let me know if you have any other questions!
Old 01-07-2009, 01:43 PM
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Berwyn Bill
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Default RE: Servo set-up for correct geometry

OK, I'm editing this and here's why...

I didn't like the layout of the rear servo bays. I couldn't see how they would make the geometry work with the long arms I wanted to use. So I spent some time try out a bunch of different arms and linkages and have found that the layout will work as long as you use 1" or so arms and not much longer than that. The geometry is still a bit funky for my taste but it will work. I just like my elevator halves to have the same geometry, I guess. I think the layout used for the dual elevator servos in the 67" Fusion would have been better but I don't design planes, I just buy 'em and fly 'em.

My 79" Yak has the same differing geometry on each half and I was able to get it nearly perfect with some end point adjusting and tweaking of the linkage.

The easiest fix if you want to get the elevator servos to be in mechanical unison is so put in an elevator servo bay just forward of the upper bay. Then you'll have both elevator servos following the same geometry in relation to the stab (one will just be a little farther away but that's not a problem).
Old 01-07-2009, 02:10 PM
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Default RE: Servo set-up for correct geometry

See Above. ^^^^
Old 01-08-2009, 03:37 AM
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Default RE: Servo set-up for correct geometry


ORIGINAL: scoeroo

OMP,

In the not so descriptive CD that comes with the new EDGE 540 80" ARF's , there is no descripition on how to set up the rear servos.

The pic's on the CD show an entirly different set-up.

The only way the servo's mount on these new model ARF's does not give correct geometry .

What is the big secret ?
I agree scoeroo, but, Team OMP, IMHO are doing better than most. Instead of flying off the handle why not try calling and asking the manufacturer how they actually set it up to achieve correct geometry with their servo set up. Besides by the time you get to a complex aircraft such as this, you should have realized by now that Instructions and plan's are just a guide line and do not have to be followed explicitly. If you don't like the way they designed it change it and do it your way.
jerrysu29 Call Sign Wild Man
Old 01-08-2009, 08:39 AM
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AFSalmon
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Default RE: Servo set-up for correct geometry

I just posted a reply to the geometry question on the probro site Bill. I'll cut and paste it over here shortly.
Old 01-08-2009, 08:53 AM
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scoeroo
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Default RE: Servo set-up for correct geometry

Jerrysu,

I'm not flying of handle or insinuating any frustrations,

I no that these planes are mass produced and if you were to put another process in the production line it would take more time ,

Time is money and the extra cost would then be pssed on down to us guys playing with this stuff,

This is by no means a complex plane as I normaly fly turbine jetts and 45%'rs , this is just a throw around toy,

Having a Phd. in electro-mechanical engineering I naturaly took on this minor issue , for every problem there is a soluton.

However - for someone stepping up to this intermediate class , the instructions are a little sparce .

I normaly just want to know where the CG is and then stick it all together and toss it in the sky and wring it out ,

Anyway , I do believe that OMP are looking into this minor but perplexing issue and should have it resolved soon.

Take care and happy landings

PS:- Just think , the Wright brothers used to build bicycles.
Old 01-08-2009, 10:04 AM
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Default RE: Servo set-up for correct geometry

Mike,

I saw the post at the PB site. I understand the variance between the two geometries will be slight but I hate having to use mixing or electronics to make up for differences in mechanics when there is a way to match the physical set-up instead.

I added a bay just forward of the upper elevator bay. Took maybe 30 minutes to mark, cut, cut the ply support, route the wire and glue it in. Now my linkages are the same on both sides and the distance from pivot plane to pivot plane is equal at both the servo and the surface (the rod is parallel to the stab). For me, it was a worthwhile mod as i love how little futzing it took to to get my Fusion's elevators matched with the same set up. Every set-up requires some end-point and subtrim adjustment, I just hate using that to make up for a mechanical difference. I'll post some pics later today.

Like I said, I have a OMP 79" Yak with the stock set-up and it works. I just like the Fusion style set-up better and applied it to the Edge
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Old 01-08-2009, 09:06 PM
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Default RE: Servo set-up for correct geometry

Cool and I like what you did here Bill. I just posted back on the bro site as well. I designed the servo layout to reduce the servo openings to two versus three so that's why it is done this way. I guess I assume everyone will use a computer radio and two separate elevator channels. I do set up the mechanical centers to be as near perfect without subtrim as possible and then set endpoints to match.

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