Seagull Decathlon – .40





In the world of Acrobatics, the Super Decathlon stands apart from the crowd. Nowadays, when people think of Air Show Performers, they conjure up images of Extras, Caps, Edges or any of the numerous bi-planes that top the bill at the local airports. The Super Decathlon is quite different in design from that type of plane, yet in the hands of a capable pilot, they can do every trick in the book.

Airshow Professional Greg Koontz Cuts A Ribbon
With His Bellanca Super Decathlon

The original full scale airplane got its start in 1951 as the Aeronca 7, and went through several changes before becoming the aerobatic trainer known as the Citabria in 1964. Bellanca took over production of the Citabria in September 1970, and with a few more modifications, it became the fully aerobatic “Decathlon”. With the later addition of a 180hp engine, it became the “Super Decathlon”.

Now, Seagull Models, who is a relative newcomer in the industry, has scaled the Super Decathlon down to an 68″ version, ready to be assembled and wrung out. Personally, I’m looking forward to this!

  • Solid Construction
  • Quality Covering (Hangar 9 Ultracote)
  • Quality Hardware – All Screws Matched With Their Mating Washers/Nuts
  • Preinstalled Pushrods
  • Preinstalled Adjustable Engine Mount
  • Spinner Included
  • Fiberglass Cowl, and Wheel Pants



  • Manual




Name: Seagull Model Decathlon ARF

Price: $139.95

68 in. (172 cm)

Wing area: 762 sq. in. (49.17 dm2)

Length: 50 in. (127 cm)

Weight per Mfg: Total: 7 – 8 lbs. (3.17 – 3.62 kg)

Actual Flying Weight: Total: 7.5 lbs. (dry)

Skill level: Intermediate-Advanced

Radio Used:
Futaba Sky Sport Transmitter

Futaba R127DF FM Rx

(6) Futaba S-3004 Servos – Elevator (2), Aileron (2), Rudder, Throttle

Channels Used: 4 total – elevator, aileron, rudder, throttle

Battery Used: 1 NoBS 4.5V 600 Mah NICD

Prop Used: Graupner 12 x 7

Required to Complete:

  • 4-channel radio with 6 servos
  • “Y” Cord (2)
  • CA glue
  • 30-Min epoxy
  • Loctite thread lock
  • Fuel Tubing
  • 50 -72 class 4-Stroke, or 40-46 class 2-Stroke Engine, and Propeller
  • Standard building tools





No matter how many times I’ve done it, opening a new airplane box still gives me goose bumps. The Seagull Decathlon was no exception. Once I was inside, I could see that all of the parts were individually bagged in translucent plastic, and nicely laid out with a cardboard divider between the main sections.



A closer look showed some interesting features. The pushrods were preinstalled, as was the engine mount, and Seagull also included a fiberglass cowl, and wheel pants. The covering job was also excellent.

A quick inventory showed all of the major components present, so it was time to get started.




Unfortunately, as with so many of the new ARF’s, the Manual is the biggest downfall. This manual however, was particularly strange in that for some steps, like installing the CA Hinges, it went into painstaking detail bordering on overkill, while other areas, like mounting the Wing Struts, simply showed a few pictures that were too dark to see details, and no text whatsoever.





We start off using CA to glue the hinges in place. As I mentioned earlier, the manual not only gives you step-by-step details here, but after describing the steps for the aileron hinges, it repeats them for both the elevator and rudder, only substituting the words “Aileron”, “Elevator” and “Rudder”.



The The next step is to use epoxy to glue the wing halves together. I found the same problem here as I did with the Seagull Spacewalker II – The Wing Joiner fit very loosely. I considered adding a piece of very thin plywood to the joiner, but ultimately, Like the Spacewalker, I just added lots of 30-Minute Epoxy to fill the gaps.

Later, after checking the Horizon website, I found this is the correct procedure. The Wing Joiner is specifically designed to be loose as to not “squeegee” the epoxy off the joiner as the joiner is inserted into the wing.

Once the joiner is installed, a piece of masking tape holds everything straight until the epoxy cures. Later, the tape is removed, and a strip of self-stick covering is applied to the seam.




The Decathlon uses one servo in each wing for the ailerons. Each servo is mounted to a hatch door which screws into the under side of the wing panel. The hatch covers are preassembled, and preinstalled (Another big time saver!).



With the servo mounted to the hatch cover, the wire can be threaded through the wing (No string supplied). Now you can line up and mount the control horn, and attach the pre-shaped pushrod.






The Tank installation goes as most do, with the only exception being the plastic fuel tubes used instead of metal. My first impression of this was that it appeared to be a corner-cutting method. However, once I got past the unorthodox material, I found the plastic to work well, and be easy to shape.

After assembly, the tank fits into the nose with the lines running through a hole in the firewall. Although foam padding was supplied, there was virtually no room to fit any around the tank.




I decided to go with an OS 70 Surpass for powering the Decathlon. This proved to be an excellent combo. The preinstalled engine mounts have elongated firewall mounting holes, so that they can accommodate a range of engine sizes. Once they were adjusted to the 70, the engine was placed as far back as possible (Which was still slightly farther out than the manual recommended), and the mounting holes were marked using a long drill bit.

The engine was then bolted in place, throttle pushrod connected, and the cowl was fitted on to the nose. I used a Graupner 12 x 7 Prop, and attached the supplied spinner.




While the photos in the Decathlon manual were clearer than the Space Walker II manual, the lack of text was a little annoying. Text really shouldn’t be necessary though, as this is a pretty straight forward procedure that anyone capable of handling this type of airplane should be able to figure out.

One really nice thing here is that even though the wheels are small, the pants are large enough to accommodate much larger wheels should you need them.

Once the wheels/pants are installed onto the gear, the gear are bolted to the fuse with 4 steel screws. Again, the screws and blind nuts are preinstalled at the factory.




Nothing unusual here. The tail feathers are placed and marked, so the covering can be removed from the gluing areas, and then reinstalled using 30 – Minute Epoxy.

After the epoxy had cured, the control horns were attached, and the preinstalled push rods were connected.


Next the tail wheel is installed. One thing worth mentioning here is that the rear screw attachment point in the tail wheel bracket is in such a tight area that it was too narrow to fit the screws supplied, however, I found that a standard servo screw with its flange ground off fit nicely.

With the tail wheel installed, it was time to place the servos. The Decathlon employs the use of two servos for the elevator. I really think this is overkill. Even though it is a very aerobatic plane, two servos is more than is needed in my opinion (but then, I feel the same way about using 2 aileron servos on 40 – size planes).





Again, I found the lack of written instruction here very annoying. While plenty of pictures are provided, several key points are missing, such as: the manual does not state that the aluminum strut attachment plates should be bent on the outboard ends, nor does it give the locations of the wing attachment points.



I not only had to guess as to where to put them, but also how to install them. I found that drilling a slightly undersized hole allowed me to screw them into the wood. I then added a drop of thin CA to secure them. I should also point out that the lengths of the struts are adjustable, so the attachment points are not critical.

Once all of the attachment points were installed, the struts bolt onto the fuse plates, and clevises are provided to attach the struts to the wing.




We’re getting close now! The supplied decals were applied, but I was disappointed to see that the white cowl stripes (which were pictured on the box) were neither painted on, nor was there a decal for it. I thought it needed something to break up all of that red, so I masked and painted some stripes on the cowl.

With the cowl reattached, and the battery placed under the tank, the Decathlon balanced right where it was supposed to. It was time to bring it out into the daylight and get a few pictures.








Maiden Flight

The day I took the Decathlon out for her maiden flight, the winds were a little gusty and variable. Not ideal conditions, but not too bad either. In no time, the OS 70 was purring, and the Decathlon was sitting at the end of the runway. The grass had been mowed just the day before, so the small wheels didn’t have much trouble cutting through it, but I could see that it wouldn’t be long before I would replace them with larger wheels. Fortunately (Unlike Seagull’s SpaceWalker II) the wheel pants were large enough to accommodate much larger wheels.

Throttle up, and she’s rolling down the runway. It was ready to lift off in no time, but I held it on the ground until a decent flying speed had been reached, as I know that a plane with such a short tail moment is susceptible to snapping if you lift off too soon. Once she was ready, the Decathlon lifted off the runway like she’d been doing it all her life. Trim requirements were minimal, and after two circuits of the field to get a feel for it, I started putting it through some mild maneuvering.

It was very responsive in the yaw and pitch axes, But the roll rate was a bit slow for my liking. After a smooth landing, I zipped up the ailerons a bit, and was back in the air.

NOW she’s flying the way I like to fly!

Rolls, spins, loops, just about anything I threw at her, she took. knife-edge flight took a small amount of down elevator, but it did them well. At this point, the winds were picking up, so after a somewhat sloppy landing, I packed up for the day.

Usually when I am doing a review, I like to get the video shot immediately after getting the feel for a new plane (Lest Murphy come up and smite me!), but the following weekend, a friend in another town was holding a fun fly at their club’s field (Which is in his backyard – Talk about lucky!). I didn’t have anything from my usual hangar ready, so I thought “what the heck”, and I brought the Decathlon.

What with the nature of the event, and seeing other fliers that I only see once or twice a year, I forgot all about the review. I was just out for a day of Fun Flying – and the Decathlon was just the plane to have with me. No smoke, no retracts, no flaps, nothing but 4 controls, and a very responsive airplane. I had a ball!

Later that week, I got the videos shot. I also got a few extra flights in, and in the weeks that followed, several more. This little plane is quickly becoming one of my favorite “Throw it in the car, and head to the field” planes. No muss, no fuss, just lots of fun!



Seagull Models
Distributed through
Horizon Hobby

4105 Fieldstone Rd.
Champaign, IL 61822
Phone: (217) 352-1913






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