ChocoFly 1:3 ASW-17S 7M GPS Racer now in stock in USA

[tewatson]

With the harnesses done, time to finish out the pre-molded fuse connector sockets. Standard stuff, though somewhat more time-intensive as there was full-thickness (~2mm) fuse layup material at the bottom of each socket. Drilled and cut to rough size, then finished by hand with small files for a snug fit. Connectors will be held in place with a dab of Goop inside top and bottom, so they can be removed if ever necessary.

[tewatson]

Working on fuse-side wing wiring. Used Emcotec 90 degree solder boards for the Multiplex connectors, to keep the harnesses tight against the fuse right from the connector. These are just a bit trickier than the other boards to arrange and solder, plus the heat shrink procedure required a bit of thought. Came out nice.

[lenb]

Tom,
Thank you for taking the time to detail the build. Although the replies to the post are few, the analytics are pretty impressive. There's a good following on this build thread.

Len

[tewatson]

Completed the wing-side wiring this week. Not going into details since it is pretty straightforward stuff, other than to say all servos are wired separately (no shared power hookups - one wire, one Multiplex connector pin). Using PowerBox premium wire and servo connectors exclusively. I really like their stuff.

The Jeti solder boards for Multiplex green connectors are the shizzle. I no longer dread soldering up these connectors. One piece of advice...when soldering the boards to the connector, make sure you have the opposite side plugged in. The pins "float" a bit in the shell, and having the connector mated holds them in proper alignment.

[tewatson]

Outer aileron servo final install followed the same procedure as with the horizontal stab - put the frame into place, then the servo, connected the linkage, and powered it up for proper positioning. With everything aligned, put a single drop of thick CA into each frame hole, waited for it to cure and removed the servo. This provided access to permanently secure the frame with epoxy where required. The result is very tight, slop free surfaces. As a plus, servo throw is at 95%.

[jgallacher]

Beautiful work Tom can't wait to see it.

[tewatson]

Prepping the outer aileron servo frames required an extra step - as the frames are reversible, they have two horn bearing post holes. One of the holes (for a left side servo arrangement) was molded off-position and would not allow the servo to seat squarely. If left uncorrected and forced into place, it would put a tremendous lever force on the horn and probably cause binding, then eventual horn failure. I briefly contemplated making ply frames and using some standalone bearing supports, but finally settled on a simple fix. Drilled the bearing hole oversize, and epoxied in a brass bushing using the servo to hold proper alignment. Ghettaux? Maybe, but works perfectly.

Otherwise. just some basic trimming for proper fit in the wing, and my usual heli-coiled screw inserts.

[Scalesoaring]

Hi Tom,

The Aluminum IDS servo arms are enroute from Switzerland. Hope to have them in a couple of weeks - FYI.

Bruce

[tewatson]

The outer aileron servos and linkage configuration was a special challenge, as the wing is extremely thin. The aft edge of the servo bay is just 8mm deep, and of course gets thinner towards the drag spar and forward edge of the aileron itself. Chocofly sets the wing up for all-internal linkages, and the main issue with such an arrangement is the resulting geometry, giving no more than 4mm of moment arm at the surface. With a 3.5mm servo horn, this requires dialing the servo throw way back, losing effective torque and relative precision.

My solution is to take the surface horn slightly above the top skin, and while not as visually clean as all-internal, it allows for 6mm of moment arm. It may not sound like much, but a 50% increase is fairly substantial and should head off potential issues. Custom surface horns were thus required, and I fashioned these from the same material used for the others. Installation followed the same procedure as before - with links connected, to verify they are perpendicular to the hinge line, and MGS epoxy thickened with chopped glass and silica.

Next is servo frame prep...

[tewatson]

Moving to the outer wing panels. Installed the inner aileron servos using a process similar to the stab servos. Secured the surface horns while ensuring the IDS arm was exactly perpendicular to the hinge line. The horns were also positioned so the hinge pin is removable (it just slips under the wiper on the inside). Important serviceability detail.

Next, drilled three small holes in the frame flanges, put the frame into position, connected the linkage, added the servo, and powered it up for proper positioning. A single drop of thick CA into each flange hole secured it, then after it cured went back and added thickened epoxy along the frame sides. The result is very tight, slop free surfaces.

Next are the outer ailerons where things get really crowded, and a whole new servo install plan.

[tewatson]

Working on flap servos in the main wing panels. The ASW-17 wing has four separate flap surfaces, and the supplied Servorahmen frames are for MKS HV747 servos. As mentioned earlier, the IDS components are beefy, with 2mm hardened steel link pins and CNC carbon surface horns/links. Prepping the control surface horns and installing them is straightforward but rather fiddly. The pockets in the surfaces are opened to rough dimensions from the factory but need final sizing/fitting, and same with the drag spar slots where the links pass through. Some of this work is ticklish business, as it's easy to let your attention lapse and cause ancillary damage. Install the horns with the links connected, so you can verify they are perpendicular to the hinge line. I use MGS epoxy, thickened with chopped glass and silica. The arrangements obviously also need to match on both sides.

When prepping the frames, pay attention to possible distortion when assembling. In my case, the servo horn bearing posts were just long enough to bottom in the frame bearing cavity before the servo was completely seated. Tightening the mounting tabs/screws bowed the frame as the servo lugs were pushed tight against their mounting flanges. The solution was to shorten the horn bearing post about 1mm (see pic). I also drilled small holes at key points in the frame, to allow epoxy to ooze through and act like a rivet.

The wing profile and servo bay size makes it all but impossible to install servos the usual way (dropping an assembled servo and frame into the bay with epoxy). My workaround is to dry-fit everything and mark the frame position so it can first be accurately placed in the bay with epoxy, then add the servo, and finally the link. Secure the control surface at neutral, power up the servo for precise positioning, check for square, and weigh down for curing. This allows you to avoid sliding the assembly all over the place and getting epoxy everywhere it isn't wanted.

The result is a clean install and very tight, slop free surfaces.

[tewatson]

For additional information on the IDS components, see post #23 here: https://forum.scalesoaring.com/forum...3150#post43150

[tewatson]

Currently working on the wings. Some additional info in response to post #8 on IDS component sizing... The ASW-17 wing has four control surfaces each side; two flaps and two ailerons. The supplied IDS kits are sized according to the requirements for each surface. The inner and outer flaps, as well as the inner ailerons, use CNC carbon surface horns/links (very burly). Flap link pins are 2mm hardened steel, inner ailerons use 1.5mm pins. Only the outer ailerons (which, at 65cm length and 4cm chord, are far smaller than ailerons on 4m F3J ships) use the IDS setup pictured in post #5.

So, while not machined aluminum a la Baudis, the supplied control mechanisms are more than up to the task.

[JimD]

Hi Bruce, in my effort to get the www.ScaleSoaring.com website up-to-date, I posted info for this model and your contact on the HOME page. Let me know if the links are okay, or if you would like some other link.

[tewatson]

On to the rudder. As the linkage is a very close fit inside the fuse blister, be sure the tail group fit is correct and the fin/rudder seats completely before starting any linkage work. You can gauge this by any gap remaining between the aft portion of the fin and the fuse. On mine, there was a blob of epoxy on the wood platform in the fuse where the vertical joiner seats, and the joiner itself was a bit long.

The next step is to cut an access hole in the rudder post. This needs to be large enough to allow your servo of choice to pass through. Servo sits on top of the tray, and the mounting screws pass through the tray from underneath and into wood blocks on the opposite side of the servo lugs.

The supplied servo tray is laser-cut ply, laminated with what looks like silver carbon cloth. The servo cutout is sized for a 20x40mm servo and I used the Hitec D945TW with 300+ oz. in. of torque. My first thought was 'why do I need such a large servo' and initially planned to use a smaller 15mm size. But, after seeing another Choco 17 with FES that required some tail weight, went the easy route and used the OEM tray and bigger servo. Extra torque for this huge rudder can't hurt, either.

The tray as supplied was too long, as it would have positioned the servo where you could not access the forward mounting screws. So, trimmed the aft end for proper fore-aft position, after which a linkage mock-up helped define exactly what vertical positioning was required. When dressing the tray sides, be careful not to remove too much as having a snug fit is just about mandatory in these tight quarters, so it will hold itself in place for gluing. I tacked it in place with a drop of thick CA at the corners, then when satisfied with the positioning, ran a bead of MGS epoxy thickened with chopped glass and silica along the edges, top and bottom.

My linkage uses a clevis at the servo, 3mm rod, and a Dubro 3mm ball joint at the rudder, mounted to a 3mm threaded brass insert. Pay attention to the linkage geometry/servo horn length, as you want the rod essentially parallel to the fuse blister profile when viewed from underneath (see pic). Watch for binding inside the fuse blister, and between the rudder/ball joint body with throw opposite the linkage side (e.g., left rudder throw with a right-side linkage setup). There is no clearance, Clarence...so you will also need to slightly shave the ball joint body in a couple spots.

Another way to do this might be with a clevis at the rudder. I'm not a fan of repeatedly levering a clevis on and off so didn't even consider it. Another factor is the geometry involved with the linkage not perpendicular to the hinge line; with reference to the linkage plane, the attachment point moves up and down with right and left rudder throw, respectively. This would put twisting forces on a clevis arrangement. YMMV.