A Thunderbolt II -10
A full-house scale model of the famous “Tank Buster” for the JetCat P-60 Turbine!
By Wallace Louie PHOTOGRAPHY: WALLACE LOUIE
This is the first of a two-part series de- scribing the design and construction of Wal- lace Louie’s remarkable turbine-powered A-10. This month features most of the basic airframe construction and also includes two of the four plan sheets for this project. The re- maining two sheets will be depicted next month, though anyone purchasing the plans in the meantime will receive all four. As you can see from the bare airframe, as well as ex- amining the photos and plans, the construc- tion techniques used are very traditional and should be well within the grasp of most ac- tive modelers. This looks like a great first turbine project. –THAYER
T 26 he A-10 Thunderbolt II (a.k.a.
Warthog) is one of the most recog- nized jets in the United States mil- itary forces today. It is easily iden- tified by its two large turbofan engines mounted behind the wing and high above the fuselage, twin vertical stabilizers, the seven-barrel Gatling gun protruding from its nose, its ordinance mounted on pylons under the wing and very often the laser re- ceiver pod hanging from the fuselage below the pilot.
The A-10’s nickname “Warthog” comes from the fact that it is ugly, flies slow and low, is heavily armored and impossible to stop. It features triple redundant flight con- trol systems, self sealing fuel tanks, ability
to fly on one engine with the loss of three feet of wingspan, and the list goes on. The model design presented here was driven by a number of factors. High on the list was keeping a low cost. It was uniquely designed to use only a single small turbine such as the JetCat P-60, Jet Central Super Bee II or other engines of similar size. In or- der to do this, I mounted the turbine inside the fuselage near the engine pods and have it exhaust directly out the rear of the fuse- lage. In flight, the exhaust is hardly notice- able, as it is hidden between the twin rud- ders and everyone watching the plane in flight is focusing their eyes on other parts of the plane, like the nose or engine pods. Inlet air for the turbine is achieved through slots in the engine pods. The engine supports are hollow and allow air to pass through for the turbine and exhaust cooling air. Additional air is fed through the fuse- lage from cheater holes in the wing. There are also some additional small air holes dis- guised by a scale-like intake on top of the fuselage between the engine pods. One other small inlet, in the shape of an NACA air scoop, is located on the bottom of the fuse- lage below the turbine for additional cooling air to the lower engine compartment. No need for custom inlet ducts. The airframe consists simply of balsa, air- craft plywood and lite-ply, with white EPS foam and rigid pink insulation foam for the
complex shapes. The entire airframe is skinned in fiberglass cloth for reinforcement and finishing. All the other hardware (re- tracts, wheels, brakes, fuel tank, etc.) is from readily available commercial off the shelf parts. Nothing is custom ordered, in- cluding the exhaust pipe that I will describe later.
Another major consideration was the field where I would be flying the A-10 most of the time. I designed the A-10 to be small and light, yet rugged enough for everyday flying from a grass landing strip. The plane sepa- rates at the fuselage and wing joint into two components for quick and easy set-up at the field and break down for transportation. I also wanted the slow flight characteristics to be forgiving for the A-10, so I selected a fair- ly thick semi-symmetrical NACA airfoil for the wing and incorporated wash-out in the wing tips.
Design of the A-10 began by collecting 3-view drawings from the internet. If you are designing a scale RC plane from draw- ings, be aware that most 3-views available on the internet or in books are merely artists’ renditions of the actual aircraft and not true to scale. Since all of the A-10 draw- ings I found had the same relative outlines, I used the one with the most detail to start my design in CAD. Before I could use the drawing, I had to convert it from the original bitmap format to
JUNE 2014
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