I recently purchased a NAN Xplorer Mark3. After looking and marveling at the craftsmanship I knew it was time to put it together.
I’m very lucky to live in an area with some amazing sailplane pilots. Jody Miller, Jeff Duval, and Dillon Graves are all local pilots that have a great track record for building great flying models. Jeff and Dillon are current USA F3J Team pilots and Jody was on the 2014 team. I’ll be enlisting each of them for help building my model.
Starting Xplorer MK3 Build
The first thing I decided to do was to cut the pushrod exits for the flaps. Even after watching Paul Naton’s F3X Build Clinic I forgot an important step, making the pushrod lines around the whole surface. This will end up showing up as an issue later. Not a bad issue, but I’ll cover it never-the-less. The above picture shows the area that will be cut out. I made it using a template. The template was created from the top of a MKS servo box. The dimensions came from using one of the clevis. I intentionally made it a bit smaller, 7mm x 17mm.
This was the hardest thing I’ve ever had to do. Cutting this hole for the pushrod exit in the center panel for the flap was so hard because the replacement cost for an Xplorer is about $700. I was worried that applying too much pressure to the drill would either damage the area around where I wanted to cut or that I’d go through the top skip like butter and then right through the bottom. Also, I was worried that if I didn’t apply enough pressure that the bit would skate around and mess up the top skip.
I took another bit and just using a good amount of hand pressure was able to make an indentation where the bit would have a guide. When drilling I didn’t apply full speed but about 1/2 speed and applied just a bit of pressure. The bit went through pretty easy. If you’re doing this be careful. It’s not like going through butter, but it doesn’t take much.
I then took a 1 1/2 inch Dremel thin cut cutting wheel and cut out the template. Again, it was hard doing this knowing that doing something bad could completely ruin the model. Cutting this opening isn’t only about removing the top skip. There is a spar that runs the length of the wing panel before the flight surface. It is necessary to cut this down to the bottom skin. Trying to use the cutting wheel to do the whole task put a small notch above and into where I made the semicircular cut. This ended up not being too much of an issue since I later had to file the length a little longer.
Notice that the cutout is perpendicular to the hinge line. This shouldn’t be done this way. If earlier I had made the pushrod line all the way around the wing I would’ve known that the cutout should have been perpendicular to the servo bay. This isn’t so much of an issue. This exit just ended up being a little off-center, tilted, and wider than the others.
I noticed that I many people complain about the hardware that comes with the Xplorer. I’ve put together a few ARFs and can say that compared to most planes, especially those coming from China/Asia, this hardware is excellent. The pushrods and clevis go together very nicely. The threads mesh really well. The clevis snap when applying closing pressure. The bolts holding the center panel to the fuse are also very nice. The threads in the fuse were clean and chasing them with a tap wasn’t needed. It’s nice that they’re also countersunk.
For the flaps I’m using MKS HBL6625‘s. These sound like they’re going to be more than enough for the task. I’m also using servo frames from Servorahmen. These frames are very nice. I highly recommend anyone putting in MKS servos to order a set of these. After getting an exit cut I wanted to check that the flap surface moved correctly through its range.
This is where I started running into issues. Following Jody’s and Paul Naton’s suggestions I used the second hole out the horn. Setting the maximum for the servo so that it is inline with pushrod and then placing the flap at 90 degrees to the wing surface I tried moving the servo throughout its range. I was only moving it about 1/2 way through when the clevis caught the top skin. To save a lot of back and forth, it took a lot of filing to make sure that I had somewhere even close to 90 degrees on the flaps. I then started working on checking the reflex amount. I only had a millimeter or two. While this would be fine for reflex/speed mode it wouldn’t work for roll coupling to the ailerons.
In the end I got the positioning of the servos good enough. I’m probably going to revisit the setup before performing the final gluing of the frames.
After a couple of long talks with Jody and re-watching the Paul Naton video, I took a different approach on doing the aileron servo. Jody sent me the following pictures to give me an idea of what to do.
I did not want to draw on my wing surface. Also, I really didn’t understand how to get tape all the way around the wing to get that line straight. I ended up using a rubber band from my 2 meter sailplane wrapped around the wing so that I could get the best idea on how to draw that line. Using my straight edge I was able to take the rubber band and make it perpendicular to the servo bay to the leading and trailing edges. Next, on the other side I took the points on the edges, put my straight edge at those points and made a the rubber band straight to those points. This allowed me to draw the lines straight (and hopefully correct).
After getting the line drawn on the pieces of tape around the servo bay and the control horn I took my template and centered it up on the pushrod line.
In the above picture you can see that I’m a little off. I ended up making it right before making the mark.
Unfortunately I should have done this on the flaps. Oh well. Live and learn, right?!
After making the first cut I noticed that there was no way I was going to get aileron travel with the clevis hitting the skin on the flight surface. I had to make another call to Jody. Turns out I still had more cutting to do.
I ended up putting on a smaller cutting wheel, one of those rust colored ones, and carefully took out as much of the aileron skin. Getting down to the epoxy on the spar for the aileron I stopped. I got out my file and cleaned up the area and made sure that the clevis would fit.
Here’s the final product. Notice that my drill skipped off a bit to one side. My pilot hole wasn’t that good on this cut.
After doing all this cutting I put one of my HV6110’s into a servo frame and lined it up. I immediately hit a wall, or well, a wing skin. I was now having the inner clevis hit the bottom skin on the inside near the servo bay. Again, another call to Jody. I’m actually wondering if I’m wearing out my welcome!
Turns out I needed to notch the servo bay.
After some initial test fits and trial movements of the servo hooked to the clevis I was ready to prep for fitting all the pieces into the wing. The two pieces of foam on the outside are from Jody. They’re sub ribs and are used for providing support around the servo bay. By tying the top and bottom skins together at this location it should make for a rock solid connecting. I’ll also be cutting some 5oz carbon fiber cloth. The cloth will be applied to the bottom of the bay (top skin) with EZ-LAM and go up the sides of the sub ribs. When the cloth becomes tacky I’ll mix up a batch of EZ-LAM and cab-o-sil to a peanut butter consistency and apply it to the bottom of the frames. I’ll take one of my ballest rods and use it to old the servo assembly in place!
Other Xplorer Build Items
Outside of working on the wings I decided to get working on creating a battery system for the model. I really like what Paul Naton did with his build of a 2s Panasonic 18650 pack.
The batteries are offset like this so that it will slide all the way forward in the nose. The space between the bottom battery and top of the fuse can be used to put a little lead to adjust the CG. The piece connecting the ends are nickle soldering tabs soldered on top of one another to lengthen them to reach each end of the batteries.
I then added on the main power lead and the balance plug. Then I pulled out the trusty multimeter to verify everything working correctly. And it wasn’t! I had the polarity switched. Luckily I caught that early! Swapping things around was pretty simple and I had the batter ready for covering in heatshrink.
This part of the build is something I’m actually not too bad at. I can enjoy soldering. I do find it tedious, though. I oped to use a pre-made harness for the wings because I just didn’t want to make pins or worry about that section of the build. Plus I want to get out and fly!
After building up the battery pack I got out all my wing servos and was going to do a quick test on 2s. I hooked up the servos I already had out in frames for test fits and then got out the other HBL6625 and HV6110. Right after hooking it up I noticed that all the servos jumped to life when the power was applied except for one! One of the HBL6625, the one just out of the box, was DOA. Luckily it was just after 6 Eastern so I got on the phone and called SoaringUSA. Annette answered the phone and I told her my issue. She said it wouldn’t be a problem to have a new one sent out and for me to send back the bad one. She was more concerned about the issue holding up the build than anything else. I tell you what, they sure do know what customer service is over at SoaringUSA. I doubt I’ll ever go anywhere else for my glider needs!
Hopefully over Memorial Day weekend I should be able to get my frames glued in and the servo harness run. That should give me some time to wait on a HV6100 and the HBL6625 to arrive from SoaringUSA. If all goes well I’ll hopefully have the model ready mid next week. That should give me some time to get out at least one evening with Jeff to get some tosses on the plane.
Stay tuned for more build action!