DYNAFLITE SUPER DECATHLON
FIELD & BENCH REVIEW
by Rick Bell
Model: Super Decathlon
Distributed by: Great Planes Model Distributors
Type: giant-scale, sport-scale kit
Wingspan: 89 in.
Wing area: 1,237 sq. in.
Weight: 16 lb., 4 oz.
Wing loading: 31 oz./sq. ft.
Radio req'd: 4-channel with 6 servos (5 high-torque)
Radio used: Futaba 9Z w/Futaba 9202 servos
Engine req'd: 1.08 to 1.80 2-stroke, 1.20 to 1.60 4-stroke, or 25 to 35 cc gas
Engine used: Saito 1.80
Prop used: APC 16x8
Street price: $159.99
Features: all-wood construction, die-cut parts, two-piece wing, heavy-duty aluminum landing gear, three-piece ABS cowl, ABS wheel pants, formed windshield and illustrated instruction manual.
Comments: the Dynaflite Super Decathlon is an easy, quick-to-build, giant-scale model that flies well and looks great. Parts fit was excellent, and the manual provides lots of information. If you like to build and be the center of attention at your field, there is no better way to ease into giant scale!
- Easy to build.
- Excellent instruction manual.
- Wide variety of engine options.
- Wonderful flight characteristics.
- Wingtips require carving.
- Starburst patterns must be cut or copied from plan.
- No decals included.
Dynaflite is well known for producing fun-scale, IMAA-size aircraft kits that are easy to build and fly great. The Super Decathlon is no exception; in fact, it's probably Dynaflite's best effort to date.
This sharp-looking, 89-inch aerobatic trainer has all the attributes sought by the first-time giant-scale builder; it's easy to build, has great visual appeal, and like its full-scale counterparts, it has wonderful flight performance. The two-piece wing is a welcome feature that provides convenient transportation and storage. In short, this plane has everything that a first-timer could ask for in a giant-scale aerobatic trainer.
The Decathlon comes in a smaller box than most large planes. It is well packed and includes lots of balsa, hardware, a three-piece ABS cowl, ABS wheel pants, a windscreen, one-piece aluminum landing gear, a rolled plan and a detailed, easy-to-understand instruction manual. The edges of the die-cut wood are sharp and cleanly cut.
The manual includes an inventory of kit contents and a list of items needed to complete the plan. It also has a building-notes section and patterns of the die-cut sheets. The plan comes rolled, and you must cut and tape two sheets together to make the fuselage. The windshield on my kit was warped, but a call to Great Planes put a new one in my hands within a couple of days.
Begin with the tail feathers; they are constructed of balsa sticks and fit together easily. The elevator tips and trailing edges (TEs) are laminated from five strips of 1/16x24-inch balsa. Old-timers will remember this type of construction; it produces a strong, light frame.
I placed pins where the instructions indicated, wet a balsa strip and pulled it around the pins to form the tip and TE. I then wet the other strips and glued them in place on the first strip using aliphatic resin instead of the recommended medium CA; it makes them easier to sand later. When the glue dried, I lifted the structures from the plan, rounded the leading edges (LEs) and TEs, added the hinges and installed the hard points for the tail bracing.
Wing. Construction is easy and straightforward, but because of its two-piece design, the lite-ply rib reinforcement subassemblies for the aluminum wing tube and the basswood main spars must be completed before actual wing construction begins. The airfoil is semisymmetrical, so be sure that the top and bottom of the ribs are correctly oriented. I also jumped ahead and joined the sheeting before I started the wing.
First, I pinned a spar in place and used a 1/4x3/8x42-inch balsa wing jig to set the correct amount of washout. Next, I added the ribs, the top spar, shear webs, remaining spars, the wing tube and the sub-LE. I then shaped the sub-LE to the rib contour and framed up the aileron bay. Last, I added the wing top sheeting and the capstrips where the directions indicated.
At this point, you can remove the wing panel from the plan, flip it over and realign it on the plan; make sure to properly place it over the wing jig to preserve the washout. Add the wing-strut-attachment blocks and the wing-mounting-bolt blocks, taper the TE sheeting, and sheet the bottom of the wing. After you have built the other wing panel, glue the LEs in place and shape them using the provided gauge to complete the airfoil.
The wingtips are made from large balsa blocks that need to be carved and sanded to shape. (I'd like to see Dynaflite use vacuum-formed parts here to save the builder a lot of carving, sanding and construction time.) After the tips have been completed, build the ailerons, hinge them to the wing, and fit the servos and pushrods.
Fuselage. The first step is to build the firewall. You can use many engines in the Decathlon, so the instructions show two firewall assemblies, depending on whether you select a gas or glow engine.
After you've built the firewall, build the three main bulkheads using balsa sticks and assemble the fuselage sides directly over the plan. True up the fuselage sides and place them on the fuselage top view. Install the bulkheads and firewall, then join the fuselage at the rear according to the instructions. Using the plan is a good idea because it helps keep the fuselage straight during assembly. The rest of the assembly goes along quickly without any problems.
To give the fuselage a little more shape, I added 1/4-inch-square balsa strips to the longerons on the side of the fuselage from the rear to the cabin windows. This eliminated the flatness on the fuselage's aft portion. I then fit the wing panels to the fuselage, squared them up, and drilled and tapped the holes for the wing-mounting bolts. I installed the fuel tank, added the forward bulkheads, and sheeted the front deck with 3/32-inch sheeting. Finally, I flipped the fuselage over to complete the built-up bottom. While the angles on the fuselage bottom look challenging, they actually go together very easily.
Next, add the tail feathers and true them to the wing. The instructions call for you to epoxy them in place at this point, but to make the covering job easier, I waited until after I had covered the plane. Because I wanted to use the starburst scheme, I'm glad that I went this route.
I then mounted the rudder and elevator servos to the middle of the rear fuselage, as indicated. Access to the servos is via a hatch that is screwed to the fuselage's bottom. I made up all of the control rods (you have your choice of materials) and hooked them up to the rudder and elevators. Be sure to use powerful, high-torque servos.
Next, make the wing struts and fit them to the airframe along with the windshield, which fit very well. Because I'm not a big fan of plastic cowls and wheel pants, I ordered a fiberglass set from Stan's Fiber Tech. The heavy-duty ABS plastic parts provided in the kit should hold up well for builders who stick with the stock units. I attached the cowl, made the appropriate openings and fitted and installed the wheel pants. Then the Decathlon was ready for final sanding and covering.
I disassembled the airframe, gave it a final sanding to remove any humps and bumps, then covered the Decathlon with Coverite's 21st Century painted fabric to achieve the look of the full-scale plane. I also used its matching paint for the cowl and wheel pants. There are many paint schemes for the Decathlon, but I liked the starburst scheme pictured on the box best. While it looks complicated, it's fairly simple when broken down to basic components.
Dynaflite provides the patterns for the starburst, but you need to cut up or copy the plan to use the pattern. It would have been nice if Dynaflite had provided a separate sheet with the patterns, and I'd like to see decals provided for the "N" numbers.
Covering the Decathlon went well; the 21st Century painted fabric is great to work with, and I was amazed how easily it went on, especially around curves. The result was nothing short of spectacular.
After the covering was completed, I reassembled the model, epoxied the stabilizer and fin in place and added the tail bracing (Sullivan part no. S546), radio equipment and engine. For that final touch, I added a polished 2 7/8 Ultimate spinner from Tru-Turn. When I balanced the model, the CG worked out right in the middle of the recommended range-a first for me!
I set up the control throws as recommended, did a final check of everything, and the Decathlon was ready for its first flight.
TAKEOFF AND LANDING
Taxi tests were as expected for a large tail-dragger-responsive and well mannered. I throttled up the big Saito, and the Decathlon was airborne and climbing away after a surprisingly short takeoff run. This was going to be fun! A few clicks of down-trim produced straight and level flight. I had so much fun flying the Decathlon that I ran out of fuel; I ran the tank dry and had to make a deadstick landing-not the ideal way to end the first flight! I'm glad to say the Decathlon glides well; I was able to make it back to the runway with no problems. The model lands like a pussycat and slows down to a walk. It's easy to grease 'em in with this one!
GENERAL FLIGHT PERFORMANCE
With that big 89-inch wing, the Decathlon behaves well at low speeds, and control response is good. Forcing the Decathlon into a stall just makes it mush forward and nose down. No trim changes were needed from low to high speed. Simply apply some power and the model quickly gets flying again. Slow presentation passes down the runway are impressive and fun to do.
Like its full-scale counterpart, the Decathlon is a great aerobatic trainer. The model handles any maneuver its big brother can do; loops tracked well and were as pretty as could be; rolls were easy from either direction. Four-point rolls were surprisingly easy, and knife-edge flight is also possible. What a great model to get into giant scale with!
The Dynaflite Super Decathlon is an outstanding IMAA-legal model that goes together easily and quickly. It looks fantastic, and its wonderful flight characteristics mean that pilots can learn giant-scale aerobatics without scaring themselves. Its all-wood construction is more akin to a sport 40-size model, and its two-piece wing makes it easy to transport and store. Want to be a big hit at the field? Show up with the Dynaflite Super Decathlon!
APC Props; distributed by Landing Products, 1222 Harter Ave., Woodland, CA 95776; (530) 661-0399; fax (530) 666-6661; http://www.apcprop.com
Dynaflite; distributed by Horizon Hobby.
Futaba Corp. of America; https://www.futabarc.com/.
Stan's Fiber Tech, 2575 Jackson St., Riverside, CA 92503; (909) 352-4758; http://www.stansonline.com
Sullivan Products, One North Haven St., Baltimore, MD 21224; (410) 732-3500;
fax (410) 327-7443; http://www.sullivanproducts.com
Tru-Turn; distributed by Romco Mfg., P.O. Box 836, South Houston, TX 77587; (713) 943-1867; fax (713) 943-7630; http://www.tru-turn.com.
21st Century Fabric; https://www.towerhobbies.com/cgi-bin/WTI0002p?P=SM&M=COV
Reprinted with permission.
September, 2001 Model Airplane News
Editor: Gerry Yarrish