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Old Jan 13, 2012, 07:18 AM
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Servo Arm to surface arm geometry

One other thing I wanted to mention was servo arm geometry.

The best case senario is to use the shortest connection possible AT the servo. The shorter the lever arm the less stress on gear teeth and any slop that a servo might have either in its shaft or between gear teeth, as well as stress to the mount is all reduced by using a shorter 'crow bar'.

(consider your teeth...each tiny metal tooth impacts its mate during launches and landings, and micro flutter causes each contacting tooth to 'peen' against its mate. The entire gear train slowly gets wobbled and wiggled and shocked with every launch ping, speed dive and especially they get rattled violently every time a nose motor is turned on) Foamie airframe absorb about 90% of that kind of abuse, and foam core wings also provide a substantial amount of dampening...but in hollow core (drum skin) construction it all goes to the gear train, gear case and ultimately the servo motor brushes get to glowing from load spiking).

That's why mounting servos flush with the surface is so important in a bagged wing....or even a moldie if the moldie has 'outie' linkages.

The surface horn connection should be double the height of that of the servo arm. 2 to 1 is the magic receipe.

The taller connection at the surface provides good leverage, allows clearance and also good travel. Its very likely you will ever see a surface flutter if it this geometry. It also provides excellent centering even with a less than precise hinge system (like worn tape hinges)....but also protects the bond of live skin hinges to the foam at the hingeline.

Wil's install is as good as it gets, the Volz Wing Maxx 'frame' mount system makes the install lean and light, yet simply by spreading the frame sides with an Xaxto blade, the servo can be popped in or out. Small set screws on either side of the servo, mate the servo case to the frame extra securely. Leaving them out and you have a 'break away' servo protection...in the case of a bad crash.

Gluing servos in is simple too. but doesn't provide the field access if needed. by the way one neat feature of a foam core wing is that if when you pull out a glued in servo, foam is pulled with it, you can simply route out the remaining foam, then fit a new piece of foam into the hole, then route that new piece down to act as a new servo base.
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Old Jan 13, 2012, 11:38 AM
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Greensburg, PA
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Solder Up.

I'm going for plug-in-play wing tips.

More on the alignment later but, we will get the aileron servos in now. You can see the slot I cut for the deans connector is a little large, later we will glue in one side, plug in the other and then glue it with the wing panels connected. I added just a little extra length to the servo wire in case I have to pull the servo. I also burned in cave for the wires to sit next to where they will pull up from the frame.
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Old Jan 13, 2012, 12:01 PM
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I haven't posted here but I've been watching every post. Awesome work, thanks for sharing!

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Old Jan 13, 2012, 12:13 PM
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Thanks Curtis,

glad you can follow along with all the typos I've left....

Waiting for lots more goodies in the mail to finish her up.
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Old Jan 14, 2012, 07:07 PM
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Servo Wire Exit Hole.

I've got many questions regarding this post. How do I find where to drill the hole for the servo wires to exit? Its quite simple when you get the wing....

I've also glued in the flap servos at this point. Same procedures as the aileron install.
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Old Jan 15, 2012, 04:26 AM
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Lovely bulid thread Will, thanks for the info, keep it coming!

For the flap install, could you show the location and the finish of the servo mounts? I am guessing your are probably going to go beyond the carbon reinforcement, but I just wanted to check.

I am also curious about the control horn in the flap to achieve close to 90 degree of movement for a bottom actuated flap, but that will be for later I guess.
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Old Jan 15, 2012, 08:11 AM
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The flap servo is half way on each panel. Waiting for servo wire and control horns to finish up.
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Old Jan 15, 2012, 10:37 AM
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Wiring for center panel.

This setup I think uses the least amount of wire and also when complete I think is worth the extra effort. Each side of the wing shares the power and ground wire. When complete I'll use two seperate 4 pin deans to make the connection to the fuse.

Before we start dremel in room for the deans plug into the end cap.
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Old Jan 15, 2012, 11:02 AM
Red Merle ALES
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Will,

I like the Deans connectors for the outer panels but for the way you're wiring your wing I really like the MPX connectors from the wing to the fuselage connection.
http://www.cheapbatterypacks.com/Pro...onnectors.aspx

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Last edited by Curtis Suter; Jan 15, 2012 at 11:18 AM.
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Old Jan 15, 2012, 11:41 AM
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Yup those are very cool! I just have some 4 pin deans around. One black one red. I'll wire them up with the male, female ends swapped so they can't be plugged in wrong.
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Old Jan 18, 2012, 01:23 AM
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Awesome Will,

thanks for posting this, as this is what I am still debating: top or bottom driven control surfaces. It would be cleaner and be better protected for landings (unless you use covers), but at a cost of added complication of having to put the servo's deeper and routing the control rod through the wing. You are doing a good job of convincing me for bottom driven surfaces.

Do you plan on reinforcing the flap servo mounting after it has been finalised? It will take quite a beating compared to the aileron servo during dork landings.
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