The vertical fin and horizontal stabilizer required more covering to be cut away on the fuselage, and to use a soldering iron to remove the covering where they would be glued. The manual has a good explanation of how to do this, being careful not to burn the wood. One omission is that the horizontal stab must be pushed as far forward in the fuselage cutout as possible to allow the metal elevator joiner wire to pass behind it. Luckily I realized this as I read the next steps before the epoxy had cured, and was able to slide it up in time. Otherwise attaching the elevator halves and rudder was uneventful, again using CA hinges.
The tail surfaces have their servos mounted nearby, which requires at least 20 inch servo extensions. This makes light weight servos important in order to achieve the correct CG without adding weight to the nose. Since no strings were run through the fuse, I taped a small lead weight to the connector and let gravity do the work. Again I used a hot glue gun to mount the servos, which use the same hardware as the ailerons to move the rudder and elevator.
 I was not happy with the tail skid for a few reasons. First, it comes in two pieces of different thicknesses which are awkward to glue together. Next, the skid attaches flat to the bottom of the fuselage without any tabs, which doesn't seem terribly strong. And finally, there is no tail wheel or metal to prevent the skid from getting chewed up on asphalt. Great Planes must have heard these complaints, because they are all addressed on the new Reactor Biplane.
Installing the electronics was easy using the provided Velcro for the receiver, ESC, and battery strap. I had so much extra servo wire I looped all three channels around the wing spar. There's a nice cooling hole on the bottom of the fuselage just behind the magnetic battery hatch, which has a 45 degree former to force air down and out of the plane. I ran the receiver antenna through this hole as recommended and taped it down.
The Reactor ARF includes a fiberglass cowl and matching spinner, whose screws are packaged inside rather than in the main hardware bag. Installing the cowl involves putting a plastic bag over the nose, putting the plywood cowl ring in place with magnets, and epoxying the cowl onto the ring. The bag keeps the epoxy off the covering and the technique works OK. I found that the cowl ring only bonded to the cowl in a few spots, so I reinforced it with hot glue from the inside. Then I drilled a hole in the cowl for cooling, which probably would have looked better if it was molded that way.
The plastic canopy comes ready to be installed without any trimming, which I appreciated. The manual suggests taping it down, but it could also be glued or screwed. After setting the control throws the build was finished, taking about 15 hours. It's worth noting that I'm a slow and meticulous builder, and took about 100 photos in that time as well. I'm sure the Reactor could be completed in ten hours or a bit less by someone with a few ARFs under their belt.
 I took the Reactor for its maiden flight on a mostly calm winter day, and hand launched it easily. It turned out to be gusty at altitude so I brought it down after a couple minutes to adjust the trims. The Reactor floated down very gently with the motor off, especially for a stunt plane. I made a slightly bumpy landing, but nothing out of the ordinary, so I was surprised to see the front of the motor box break. This was doubly surprising as I had used epoxy for a stronger bond, and had not even damaged the propeller.
Back on the bench, I decided to beef up the motor box with six strips of plywood, three inside behind the front plate, and three outside against the firewall. I also reattached the tail skid with had broken on landing, this time stripping the covering properly before applying epoxy. So it wouldn't be all repairs, I added a few decals, put down a metallic charcoal trim sheet in the cockpit, and reattached the canopy with double stick tape. These small touches add up to one sharp looking plane.
Subsequent flights went smoothly. The large ailerons made for quick rolls even on low rates, and the Reactor was easy to control despite the 3D name suggesting it's for experts only. The large rudder made for beautiful stall turns, much better than I'm used to with a trainer. The Reactor also handled a 10 mph wind well, both in the air and during landing with almost zero ground speed. I routinely flew for nine to ten minutes on the 2100 mAh pack without hitting the low voltage cutoff, even though I was near maximum throttle most of the time.
 The 10x4.5 prop with the 35-30-950 motor and the heavier battery make for a leisurely combination. The power is fine for basic acrobatics but the Reactor does not climb strongly with this setup. I'd be curious to try other propellers and even 4s packs, but I had neither on hand. For now I may stick with a lighter 3s 1500 mAh battery to shave a little weight off.
 All in all I'm very pleased with the Reactor. It looks great and attracts a lot of compliments at the field, and is both capable and forgiving in the air. Like many small ARFs the landing gear could be beefed up and the wheels should be larger, but these are minor issues. I'm looking forward to building my acrobatic skills on this well-designed ARF. Definitely recommended |
Everything was going well until I opened the manual bag, which contained four addenda. The first three had been available on the Tower Hobbies site when I ordered, so I was already familiar with those construction notes and the suggestion to use an 11x3.8 SF prop instead. However the last addendum had some disappointing news: Great Planes had revised their recommended power setup to use the 35-30-1250 motor instead, which requires a 35 amp ESC to handle the higher current draw. 
I debated returning these components which I had already opened, including the motor which unfortunately comes in a blister pack which needs to be cut open. I decided to check Adam One's motor calculator to compare the two setups, and found that the 1250 kV motor and suggested 10x5E through 10x7E props would provide a higher top speed, but actually have less thrust. They would also draw about 30 amps instead of 20, which would strain my batteries more and mean shorter flight times. I decided to stick with the components I had. 
The instructions begin with assembling the wings. The ailerons are positively huge, and run the whole length of each wing. Each is secured by four CA hinges, and nicely beveled for full deflection. Like many other aspects of the construction, the holes for the aileron servos are covered over and need to be opened up. This was easily accomplished by tracing the outline of the hole with a new hobby knife, and no ironing was needed on the edges. 
The manual called for both aileron servos to be glued with CA or epoxy, which I don't care for. This was a little puzzling since there was plenty of wood to bite into with screws. Since I didn't have any on hand (Futaba does not provide screws with the S3114's), I chose to use hot glue instead. While this probably gives the least attractive results, it's easy to peel off if I need to remove the servos in the future. 
Unlike many planes which involve fishing aileron servo cables through the wing, the Reactor's servos sit so close to the inboard edge that the servo leads came right through. ElectriFly specifies two 6 inch servo extensions, but these would only be needed if attaching the ailerons to separate channels. Otherwise, even the shortest Y-cable would be more than long enough, which is the route I took. 
Next was the trickiest step of the build: permanently attaching the wing halves to the body. The ARF comes with pieces for two wooden jigs, which when glued together support the wing tips and create the correct dihedral, i.e. essentially none. When dry fitting the wings I found they did not fit flush against the fuselage, and the culprit turned out to be excess covering. The slight overlap from the fuse sides into the wing bay was surprisingly taught and needed to be trimmed back, which solved the problem. It's important to weight down the fuselage, after which it was easy to epoxy the diagonally-interlocking wing spars to each other, and the wing spars to the body. Two pieces of plywood are epoxied on either side of the wing spar for strength after the original bonds set. 
While waiting for things to dry I skipped ahead and built the motor box. The ARF provides two sets of precut plywood to accommodate both inrunner and outrunner motors. I built the outrunner box with 6 minute epoxy instead of CA to have more time to align and clamp everything, which turned out to be a good idea. When built correctly, this box includes a small amount of down thrust and right thrust. Another piece of plywood replaces the aluminum motor mount and worked perfectly with the ElectriFly motor. 
I was not happy with the tail skid for a few reasons. First, it comes in two pieces of different thicknesses which are awkward to glue together. Next, the skid attaches flat to the bottom of the fuselage without any tabs, which doesn't seem terribly strong. And finally, there is no tail wheel or metal to prevent the skid from getting chewed up on asphalt. Great Planes must have heard these complaints, because they are all addressed on the new Reactor Biplane. 
I took the Reactor for its maiden flight on a mostly calm winter day, and hand launched it easily. It turned out to be gusty at altitude so I brought it down after a couple minutes to adjust the trims. The Reactor floated down very gently with the motor off, especially for a stunt plane. I made a slightly bumpy landing, but nothing out of the ordinary, so I was surprised to see the front of the motor box break. This was doubly surprising as I had used epoxy for a stronger bond, and had not even damaged the propeller. 
The 10x4.5 prop with the 35-30-950 motor and the heavier battery make for a leisurely combination. The power is fine for basic acrobatics but the Reactor does not climb strongly with this setup. I'd be curious to try other propellers and even 4s packs, but I had neither on hand. For now I may stick with a lighter 3s 1500 mAh battery to shave a little weight off. 
All in all I'm very pleased with the Reactor. It looks great and attracts a lot of compliments at the field, and is both capable and forgiving in the air. Like many small ARFs the landing gear could be beefed up and the wheels should be larger, but these are minor issues. I'm looking forward to building my acrobatic skills on this well-designed ARF. Definitely recommended
