A few years ago, Top Flite introduced their “Gold Edition ARF” series. With airplanes like the Cessna 310, and most recently, their P-51D and B-25, this has been a fantastic assortment of quality airplanes. The latest addition to the series is the new AT-6 Texan. Based on the most famous WWII fighter trainer, the new Top Flite AT-6 is an excellent representation of this classic.
Designed as the NA-26 by the North American Aircraft Company, it was developed as a Basic Combat trainer and originally designated it the BC-1. The prototype BC-1 first flew in 1937, but in 1940, its role was changed to advanced trainer and it was given the new designation, AT-6.
The AT-6 Texan was the most extensively used trainer of all time with more than 17,000 built and was used to train more military pilots from more countries of the world than any other aircraft ever built before or since.
With a reputation like that it is easy to see why Top Flite picked the Texan to enter its Gold Edition lineup. Let’s take a deeper look.
Name: Top Flite AT-6 Texan 60 ARF
Wingspan: 69″ (1755mm)
Wing Area: 730 sq in (47.1 sq dm)
Weight RTF: 8.5 – 9.5lb (3855 – 4310g)
Wing Loading: 27 – 30 oz/sq ft (82 – 91 g/sq dm)
Length: 51″ (1420mm)
Airfoil: Fully-symmetrical, low-wing
CG: 4 1/4″ (143mm) Back from the wing’s leading edge
Engine: .60cu in (10cc) 2-stroke OR .70 – .91 cu in (11.5 – 15cc) 4-stroke
Items Needed To Complete
Engine and Prop
Receiver Battery: 1000mAh capacity minimum
Servos: 7 Standard (2-Aileron, 1-Elevator, 1-Throttle, 1-Rudder, 2-Flap) 1-Retract Servo
Servo Extension 12″ (7 required *)
Servo Extension 6″ (1 required *)
2 “Y” Cords
Medium CA or other glue
8-32 tap and #29 drill bit
Foam Padding for Tank
Medium Fuel Tubing
Various Hand Tools
* Note: In the “Items needed to complete” section of the manual, it lists one, 6-inch and seven, 12-inch extensions. In reality, no 6-inch extensions are required and only five, 12-inch extensions are needed.
- Great Scale Appearance.
- Excellent MonoKote Covering Job
- Scale Aluminum Spinner
- Excellent Flyer
- Wheel collar set screws did not fit.
O.S. 91 Surpass II
Tx: Futaba 6EX
Graupner 14×7 (GP14070)
The overall packaging on the AT-6 Texan was good. All items were individually wrapped in plastic bags and securely taped in position. All parts were present and accounted for, so it was time for a closer look.
Viewing the inside of the fuselage, the construction looked to be excellent. The wood quality was top-notch and all glue joints looked secure.
Some features worth noting are the 3-piece wing that sports a 3-section, split flap arrangement, nice-looking scale hubcaps and a quality, scale aluminum spinner. Other goodies include two pilot figures, instrument panels and a pre-cut, pre-painted canopy.
The first step is to secure the MonoKote with a sealing iron. Even if the manual didn’t tell you to do this, I always make a point of double-checking the covering job. For the most part the covering was excellent, but as always there were a few areas that needed a touch-up, especially the control surfaces, which were the only areas that were over open structure.
Once the covering was secure, it was time to prepare to install the hinges. For the ailerons, CA hinges are used. I started by drilling a “wicking” hole and proceeded to apply the hinges.
For the flaps, Top Flite supplies pin-type hinges. After melting some petroleum jelly into the pivot, I installed them into all three wing sections with slow-curing epoxy and let them setup overnight.
AILERON AND FLAP SERVOS
The flap and aileron servo mounting blocks are now epoxied to the hatches. I always like to scratch the mating surfaces to give the epoxy a little extra grip. This may not be necessary due to the fact that the blocks are later secured with screws, but it’s a good practice. (Note: Remember to place the screws low in the mounting blocks so they don’t interfere with the servo screws!)
When the time comes to mount the servos, I like to place a folded matchbook cover between the servo and the hatch as a spacer. Next, you need to enlarge the hole in the servo arm to accommodate the pushrod wire.
I found that I needed to trim away just a hair from the plywood hatch support to clear the servo mounting blocks. It could have been just my servo placement because I didn’t have to do this on the flap servo hatches, which are identical.
Once the assemblies are complete, the hatches are screwed in place, and then removed so the screw holes can be hardened with thin CA. This is standard procedure for every screw that will be going into wood.
Now the aileron control horns are attached. Like most of the control horns, they are secured with two wood screws that go into a plywood plate. I have used this method many times without ever having a failure, but remember to harden the holes with CA! Once the control horn is secured, the pushrod is marked, bent to a 90-degree angle, cut to size and secured to the servo arm with a nylon Faslink.
The flaps are rigged in the same fashion. The only differences are that the flap control horns are mounted backward for a better mechanical advantage, and you must place both servo hatches facing the same way to avoid them moving like ailerons. I was a little flustered at this point that the manual has the flap servos placed opposite to the way mine were. But it really doesn’t matter whether they both face right or left as long as they both face the same way (As opposed to the aileron hatches which must face opposite directions).
One more thing worth noting here is to have the servos plugged into your radio and powered up with trims set to neutral while setting up the linkages.
Joining the wing is a bit more complicated than it looks on the surface, not difficult, just intricate. For one thing, the servo leads must be guided through the center section as the two sections are joined. Secondly, actuator pins, which join the center flap to the outer flaps, must be inserted into the center flap as the joint comes together. And finally, there are three wing sections, which means that once you have done all that to one side, you have to do it all again to the second side.
As for the actual gluing of the wing joiners, I used Epo-Grip #30 paste. The long working time and thick, non-running consistency of this epoxy made for one less thing to worry about during the joining process.
My timing was perfect; it was late in the evening, so the wing was left to cure until I got home from work the next afternoon.
I have been using a new epoxy lately called Epo-Grip from Newton Supply Company, Inc.. Epo-Grip is produced for the Taxidermy and Furniture Repair industries, but after some extensive tests I have found that it works great for many of our modeling applications. It comes in many varieties including a fast and slow-setting formula.
The fast-set will give 6-10 minutes of working time, while the slow-set (Called “#30-Paste”) has more of a two hour working time. Now this is a lot more working time than the 30-minute epoxy I’m used to, and to be honest, if it’s a little cold in the room, it can take several hours to completely set up, but the one big advantage that I really like is that it is a paste, not a liquid. Once mixed, it has the consistency of Petroleum Jelly (Vaseline), so when you put it somewhere, it STAYS there and won’t run all over the place. I have used it very successfully for gluing stabs/fins to fuselages and other typical joints that require epoxy, but two things I really like using it for are pinned hinges and for joining wing halves (Where you can smear the paste on the wing joiner and inside the slot and it doesn’t all drip to the bottom). All in all, I’m very happy with Epo-Grip’s adhesives and I’ll continue to use them.
FINISHING THE WING
With the wing joints fully cured, it was time to add the forward wing dowels and the joint covers. The joint covers are marked, small sections of covering are removed from underneath them, and they are epoxied in place.
To install the retracts, Top Flite supplies a 12-inch section of pushrod tubing which you thread from the servo opening to the retract compartment. You then use this tube as a guide for the pushrod. Once the pushrod is in place, the tubing is removed.
The units are now secured with #4 screws, but they are not connected to the servo until later when the rest of the radio is installed.
Now the wheels are added. I found that none of the supplied set screws fit into the wheel collars. I don’t know if they were the wrong thread size or if the collars weren’t fully tapped, but the set screws were not going to go in. I had some 6-32 set screws, so I drilled and tapped the holes for a 6-32 thread and mounted the wheels. Finally, the hubcaps are snapped into place and the wing is finished!
Tail section prep begins with removing the covering on the center of the stab and checking the elevator control horn fit in the rear stab block. Now the control horn is attached to the pushrod, the pushrod is inserted into its plastic guide tube and the rear block is put in place.
Next, the stab is inserted, the alignment is checked and when all is well, the stab is epoxied in place. The manual has you glue the rear block to the back of the stab prior to gluing the stab, but I chose to skip this and (Carefully) glue the block to the stab and fuse with a little thin CA after the stab was in place.
Once the epoxy had cured, the elevators are glued to the joiner wires with epoxy and CA hinged to the stab. A trial-fit beforehand showed that I needed to enlarge one of the joiner wire holes slightly for a good elevator alignment.
The tail wheel bracket is installed with epoxy as the rudder is hinged. Once the glue was set, the rudder horn is attached to the pushrod and the pushrod is inserted to get the proper horn alignment. With the rudder horn in place, the mount holes can be drilled and the horn screwed in place.
ENGINE AND TANK
The OS 91 four stroke is a ringed piston engine which puts out 1.6bhp while weighing in at only 23 oz with muffler. It’s practical rpm range is 2,000 to 12,000 rpm. Full specifications are below:
Bore: 27.7mm (1.09″)
Stroke: 24.8mm (.976″)
Displacement: 14.95cc (0.912 cubic inch)
Power Output: 1.6 BHP at 11,000 rpm
Practical RPM Range: 2,000 – 12,000 rpm
Crankshaft Thread Size: 5/16″ x 24
Weight: w/o muffler- 21.3 oz (603g) with muffler- 23.0 oz (655g)
The manufacturer recommends this engine be run on fuel containing 5% to 15% nitromethane and oil content at a minimum of 18%. I chose to use Cool Power with 15% nitro and 18% synthetic oil as I’ve found it runs extremely well in all my engines and especially the 4 strokes. The synthetic oil helps to keep the 4 stroke cleaner while castor can gum them up over time.
Some of the advantages of the 4 stroke engines are fuel economy, their ability to swing a larger prop, and (My favorite) that cool 4-stroke sound!
Props recommended by the mfg. for the OS 91FS are:
Stunt planes: 11 x 11-12, 12 x 10-12, 13 x 9
Scale models: 13.5 x 8, 14 x 7, 15 x 6, 16 x 6, (12 x 8 & 12.5 x 7-3 blade)
The prop used for this review was a Graupner 14×7 (GP14070)
This version II of the OS 91 sports more power than its former model and comes with a full 2 year warranty from OS
Now it’s time to install the engine mount, locate the engine and mark its location. For this I like to use the Great Planes Dead Center Hole Locater.
Now the holes can be drilled and tapped for an 8-32 thread. A little trick I like to do with composite mounts is to stop tapping the hole just as the tap comes through the far side. This makes the mount act as a lock nut and keeps the screws from vibrating loose.
Next the throttle arm position is located and a hole is drilled for the pushrod tube. Depending on your choice of engine, the pushrod may need to be bent slightly to reach the throttle arm.
There’s nothing special about the tank that you haven’t seen before. Hopefully if you’re building a plane like this, you’ve assembled a tank or two. I do however really like the tank/radio tray. More on that later.
The receiver and battery pack strap to the underside of the tank tray. The tray is then inserted into the back of the firewall and secured with two screws at the rear. I finished off the radio installation with a DuBro Kwik Switch/Charging Jack.
Mounting the cowl begins by gluing four hardwood blocks to the front of the fuse. The cowl is now aligned and the mounting holes are drilled. I placed a piece of tape over each block to mark the location of the holes. Then I peeled the tape back, aligned the cowl and re-seated the tape. This not only held the cowl in place, but it also gave me the perfect spot to drill.
The dummy radial needs to have a cooling space removed and holes drilled for the addition of the pushrod tubes. When finished, it looks great!
The dummy radial is held in place with sticks and rubber bands while you align it to the engine. Once it’s in place, I secured it temporarily with a few strategic drops of CA until the cowl was removed and it could be properly glued from behind. Next I added a DuBro Fill It Fueling System With the addition of a Graupner 14×7 prop and the supplied spinner, we’re really getting close!
There are three final additions to the nose – an exhaust stack and two air scoops. I removed a small amount of covering to glue on the exhaust stack, but I just punctured holes where the scoops will go.
The cockpit floor can now be glued in place, but I didn’t like the idea of just gluing the pilots to it. I found that a piece of half-inch dowel fit perfectly into the hole that was in the bottom of each pilot, so I glued a dowel into each of them and drilled two holes in the cockpit floor for them to sit in.
I used RC-56 to secure the canopy and once it was cured, all that was left was to add decals and bring this beauty into the sunlight!
Special thanks to Tina from Stallion Ranch for posing with her!
The first day out with the Texan was less than ideal, but winter is beginning to set in, so I was taking advantage of every halfway decent day I got. I cranked up the OS 91 and started to taxi around a little. On my first high-speed run, the plane leaped off the ground. It startled me a bit, but I was able to recover and set it back down safely. “WOW” I thought, “She seems really tail-heavy!”
Since there was a fairly nasty cross wind, I decided to pack it in for the day and wait for better weather.
Back in the shop, I decided to re-check the CG. It was dead-on. I then checked the manual for the control throws and found that my usual “That looks about right” method was way off. The manual recommends 5/8″ elevator throws on the high rates and I had more like an inch. So I turned them down and added an ounce to the nose just to be on the safe side.
The next time out, we were being graced by an unusually nice day. It was cold, but sunny and dead calm. Soon, I was sitting at the end of the runway and poured the coals to her again.
The second takeoff was a lot less exhilarating, but nonetheless the AT-6 left the runway much sooner than I was expecting. Once airborne, and after a few minor trim adjustments, it tracked well and flew quite nicely, but it still seemed a little squirrelly in turns – again a sign of being tail heavy. I landed her and added another 2oz of lead to the nose.
Now she flew with a lot more authority. The CG was only about 1/4″ forward of the recommended 4 1/4″ but it helped a lot.
Ok, time to put it through its paces. The AT-6 was very maneuverable and looked great in the air. It has no bad habits and in no time, I was really enjoying the flight. There was a noticeable amount of ballooning when the flaps were dropped, but she soon settled in and floated quite nicely, so I see no need to mix in and elevator compensation. She lands nicely too, although due to the forward-rake of the gear, combined with the coil in the gear wires, you need to watch out for bouncing – hard to do on our bumpy runway – but still, I was able to grease her in on several landings.
I will apologize now for the video, but I had several things working against me. For one, winter was setting in – we had already had 2 dustings of snow and I know how nasty the weather can get at this time of year, so the first time I had an available pilot and halfway decent weather, I jumped at the chance – even though other conditions were less than ideal.
The next problem was that the cone on my electric starter had a narrow cup, which would not stay on the bulbous spinner of the Texan, and due to a bad case of tendonitis in my right arm, flipping the prop by hand was out of the question, so in the video, you’ll notice we were flying it without the spinner. But it was either that, or wait till next spring to shoot some footage! Special thanks to my fellow club member and pilot, Rick Kacher for braving the cold with me!
Check out the video to see her in action!
The AT-6 Texan is another terrific plane in the Top Flite lineup. The scale details are about as nice as you’ll find in an ARF package. Assembly does require the full amount of time listed, but something this nice doesn’t go together overnight. All in all, I’m very pleased with its looks, quality and performance.
Great Planes Model Distributors
P.O. Box 9021
Champaign, IL 61826-9021
Futaba Corporation of America
Great Planes Model Distributors
P.O. Box 9021; Champaign, IL 61826-9021
Distributed Exclusively in the U.S.A., Canada and Mexico by:
Great Planes Model Distributors
P.O. Box 9021; Champaign, IL 61826-9021
Everything For The R/C Hobbyist