The day I bring home a new airplane is always exciting. The day I brought home my Hangar 9 Aermacchi MB-339 was extra special.
My goal was to make 2024 the “Year of the Jet”. I set that goal for myself when I was at the “Illini Jets” jet meet at Eli Field in 2022. At the time, I had no idea how I was going to make that happen, and I had no idea what my first turbine aircraft I was going to be. Unbeknownst to me, Horizon was about to release the MB-339. It was announced at the perfect time for me to realize choosing this as my first jet was a no brainer.
I’ve always been drawn to turbines. There’s just something about the way they fly, their sounds, their smells. I’m comfortable enough with setting up and flying electric, gas, and even glow airplanes, but turbines seemed to be an entirely new animal. And while it’s true that there are certain things that are turbine specific, they’re really not much more difficult than any other source of thrust. It could even be argued that installing a turbine is quite a bit easier than installing a gas, glow, or electric motor.
Tommy was pretty excited to help assemble a turbine airplane, so he came over and helped out with it. You’ll see him a lot below because I was the one taking pictures. I swear he didn’t do all of the work!
Follow along with the build below. This is not meant to be a replacement for the assembly manual, but we will talk about how the build went for us as a first time we assembled a turbine ARF. This page will be updated as more progress is made. Feel free to reach out to me if you have any questions at ron@rcplanelab.com. Let’s get started!
The first step out of the box was to install the hinges on the flaps. It was quite obvious that the hinges were not drilled straight from the factory. Luckily, this was an easy fix. We drilled out and oversized the holes for the hinges and used microballons mixed in with the epoxy to fill the extra space. We were able to get the hinges to line up without any problems and it turned out pretty good.
The next optional step was to cover the inside of the wing panel behind the flaps so it wasn’t bare wood. We could have skipped this since it will mostly be hidden, but we figured that we might as well give it a finished look. Covering a small space that was this intricate was a bit of a pain, but worth it in the end as it does make the airplane look better. Even though it will most likely not be noticed by anyone, I know it’s done and it makes me feel better!
Next we cut out and covered the recessed portion of the flap where the control horn mounts.
Hinging the control surfaces was easy. We start by dipping the moving portion of the hinge in melted Vaseline to keep the epoxy from getting into it. We melt the Vaseline by putting it in a metal lid and setting the lid on top of a covering iron. Be careful not to spill it! After the epoxy is added, be sure to move the control surfaces back and forth to make sure the hinges are all aligned properly.
I’m a big fan of these control horns. Be sure to roughen up the surfaces that will be in contact with the epoxy. I used sand paper. I like these because there is a lot of surface area for the epoxy to grab on to, and they install and align easily.
We carefully cut the covering from the retract bays, leaving just enough overhang to iron down to give it a nice and finished look.
The front landing gear installation was next. The steering servo mounts on the retract and moves with the gear. There was a bit of an angle on the ball link on the end of the push rod.
Drilling holes to mount the receiver and turbine control module was a little bit more difficult than expected. Finding a spot where the receiver mounting holes would line up was a challenge, but we found a spot that worked out great.
Installing the thrust tube was fairly straight forward. The manual said to install the fuel tank first, but the thrust tube would not have fit with the fuel tank installed. Sliding the tube through the opening in the fuselage was tight, but doable. We used a thin piece of card stock as a guide to finagle it through.
This is the mounting plate for the fuel tank. No matter what we tried, we couldn’t get all four thumb bolts to line up, so we had to drill out two of the holes to make up for the mis-alignment in the fuselage.
This is when it starts to look like a jet! This is also the other part of the airplane that had alignment issues. The right side of the fuselage has a gap in it that’s about 1/8″ at the top of the joint. There are 2 metal straps that get bolted onto the inside of the fuselage to hold it together. The left side fit fine, the right side had to be drilled out to accommodate the gap. The gap does not go all the way down the side of the fuselage. It’s only about 3 inches, so the mating surfaces weren’t completely straight.