Radio Control Giants
Sal Calvagna [[email protected]]
Scratch-built de Havilland Turbo Beaver
Heyward MacDonald of Charlottesville, Virginia, scratch-built a wonderful electric-powered, 10-foot-span de Havilland Turbo Beaver using three-views and photographs he found on the Internet. He downloaded the airfoil data points and plotted them into Excel to fabricate the wing and horizontal stabilizer ribs. He also drew full-size plans from which to build.
The de Havilland Beaver is a popular high-wing, radial-powered STOL (Short Takeoff & Landing) airplane that de Havilland Canada designed primarily for use as a utility aircraft. It was coined a “bush plane,” because it was capable of hauling cargo and passengers into remote areas. The Beaver was also used as a crop duster and was widely adopted by the armed forces as a utility aircraft. It first flew in 1947, and more than 1,600 had been made when production ended in 1967.
Heyward chose the Turbo Beaver as his project since it is extremely stable and has a nose structure that is easy to translate to electric power. The full-size Beaver’s original radial engine is now out of production, which makes replacement parts harder to find. Some conversion stations have replaced the radial with a turboprop (for example, the Pratt & Whitney PT6). The added power and lighter installed weight, along with greater availability of kerosene, make this desirable — though costly — and approximately 60 Turbo versions have been converted. In the RC world, turboprop aircraft can be good candidates for electric power. Heyward’s model needed no additional weight to achieve the proper CG.
Excerpts from Heyward’s submission:
“The wings of the Turbo Beaver were the same as the full-size aircraft. On my model they are cantilevered and have a 3/4-inch aluminum tube with a small bit of dihedral. The struts are strong, with aluminum bars laminated with balsa and shaped to the same airfoil as the lifting surfaces.
“I weighed the 3/32-inch sheet I had planned to use to sheet the wings and found that my 1/8-inch sheet was lighter, so the wings are completely sheeted with 1/8-inch balsa. The wings have large flaps and ailerons powered by FMA Digital 300 servos. Additional aluminum tubes join the outer wing panels.
“The fuselage is box-framed with quarter-formers and 1/16-inch sheet. Each large elevator half is powered by its own servo. The vertical stab on the Turbo Beaver is huge to provide stability for water operation. Most Turbo Beavers were produced with floats, which gives this model a lot of stability.
“The stab is a zero-lift airfoil and not a simple fin. It too is sheeted, as is the horizontal stab and elevator.
“The model has a huge cargo bay with a 1/16-inch plywood floor, which I can use to mount loads I have not thought of yet. I didn’t bother to build the doors and fly the plane with the large cargo doors off. It looks kind of neat in the air that way.
“The rear doors are hinged and locked closed with earth magnets. They provide access to the receiver, the switch panel (including the safety arming system), and the Co-Pilot Flight Stabilization System, which is really not needed for this plane.
“The electric motor is one of those 63 mm motors from China. I have tested dozens of them and find some manufacturers build junk and some build really fine motors. This is a fine one. I have run it at 3,200 watts and it blew the rakes off the wall of my garage. I do believe my SUV was rocking. (That prop would cut a cow in half, so safety is paramount; ergo, the safety arming system.)
“The ESC is a 100-amp / 12-cell unit. The battery packs were the 5-cell FMA 5300s. The FMA Cellpro 10s works beautifully to keep these battery packs operating for the long term.
“The wing is in three pieces with the center part designed to fit the width of a typical SUV. The struts fit to the tips of the center section and the outer panels have an aluminum tube that slides into a fiberglass tube. All that is needed to set up the model at the airfield is to slide the tubes into the center wing section and attach the servo. There are two Ikea furniture torque locks on each center-section tip that serve as incidence pins and lock the wing panels together. I can fly in five minutes after arriving at the field.
“The model is intimidating because of its size and the sound that big prop makes when it roars down the runway. It lifts off in about 80 ft and climbs at a steeper angle than expected, but it flies like a Super Cub. It maneuvers in the sky in a scale-like manner and slows down to a crawl, especially with those big flaps.
“On its first landing, it greased in without a bounce. The landing gear was fabricated of 1/4-inch aluminum and it has soft five-inch wheels.
“This is an amazing sight in the air and a lot of fun to fly. The model looks like the real thing in the air. It jumps off the ground with all that power and 2,000 sq in of lifting surface and is very easy to fly. It is like a slow freight train flying overhead. It took me 700 hours to design and build.”
1/3-scale Fokker D.VIII — Barry Herthum
Barry Herthum of Summerfield, North Carolina, built a 1/3-scale Fokker D.VIII from a set of Ron Weiss plans. The model spans 110 inches, has a length of 73 inches, and an all-up weight of roughly 30 pounds.
The Fokker is powered by a Zenoah GT-80 twin-cylinder gas engine and is equipped with slimline mufflers modified to accommodate a smoke system. Barry uses the Sullivan SkyWriter battery-powered smoke pump to send smoke fluid into the mufflers. He installed a pilot from Aces of Iron.
Barry built the model so he can join the dawn patrol flights at Warbirds Over Delaware. According to him, the D.VIII is easy to fly and “handles like a Cub”; however, Barry claims that it lands “like a chicken with its head cut off.” It seems like he’s been spoiled by years of flying WWII models — welcome to WWI aviation.
Polikarpov I-16 progress
With a full-time job, a part-time job, and authoring this column, it’s been difficult to find spare time to work on RC models. Nevertheless, I stole a few hours here and there to press on with the Polikarpov I-16 build.
Recent progress includes adding detail features to the cowling. I used flat brass strip and brass tubing to make the gun ports and the triangular-shaped intake. The gun ports were straightforward: I cut two sections of an appropriate-size brass tube, drilled the holes into the cowling, and glued them in place using thick CA.
I bent a piece of 5/8-inch-diameter brass flat stock to shape and soldered it to create the intake. As with the gun ports, I used thick CA to glue the intake in place.
I made the large gun covers from a 5/8-inch-diameter wood dowel that I cut diagonally and glued to a 1/32-inch plywood base. The front halves of the two gun covers are attached to the cowling, while the rear halves are attached to the fuselage. I coated the four pieces with finishing resin and sanded them before installation.
What’s left to complete are the faux cockpit doors, one on each side, and the canopy (windscreen). Stay tuned as this project nears completion.
That’s all for now. Don’t be shy — please let me know if you have any questions or concerns. Have a great time at the field! MA
Sources
- International Miniature Aircraft Association — www.fly-imaa.org
- Ron Weiss plans — (631) 427-7312
Transcribed from original scans by AI. Minor OCR errors may remain.
