Phony Folkerts. Radio control FAI pylon racer model. Wingspan 56 in, wing area 605 sq in, for .40 power.
Quote: "Phony Folkerts. The next time you get fooled on the FAI circuit, it could be by a real phony. Although its looks are somewhat fake, its speed around the course is for real. Phony Folkerts, by Bob Root.
In deciding to build a competitive new FAI racer, the design requirements seemed to suggest a minimum sized 'thing' configuration. However, I have always felt that model racers should look like full-scale airplanes. The model presented here as the Phony Folkerts represents a compromise between these extremes. Although the model retains some of the basic outlines of the Folkerts SK-2, and SK-3, it cannot be suggested that it is stand-off scale, unless one stands off 400 feet to watch it race.
However, racing is what this design does best. it has been quite competitive in the Northwest in FAI, and finished well at the 1973 NATS, with Jim Booker and Bob Root placing third and fifth respectively.
The Phony Folkerts fuselage cross section was minimized for low drag by designing the basic fuselage to be just large enough for the necessary equipment. The FAI width and height requirements were then faired into the small cockpit area as smoothly as possible. A fiberglass fuselage was incorporated to minimize structural volume, while allowing complex curvature and rapid construction. Although this type of construction deviates from the author's usual methods of wood construction, the results have proven worthwhile. A high quality, lightweight, fiber-glass fuselage is now readily available.
While the design and construction of the original plug, mold, and model took all winter, the second one was built in two weeks by fellow competitor Jim Booker. The fiberglass work and much of the original plug and mold building techniques were supplied by Tony Howard. He has been producing high quality, limited production, fiberglass kits for several years. Either a glass fuselage, or a complete kit, is available from Miniature Aircraft Designs. See details at the end of this article.
A few notes are included for those who may be interested in building a wooden version, but the equipment room or the cross-sectional area will have to be compromised. The complex fuselage shape does not lend itself well to wood construction.
Construction is shown for four separate types of landing gear. Violett Aero Modeling Corp retracts were used on the original model. Although this plane weighed less than 4-3/4 lb, very careful building was required. A separate article on installation of the retracts, with details of the full wheel doors, appears in this issue of AAM.
Jim Booker built his model with belly mounted wheels and 'outrigger' stabilizing skids. This landing gear is simpler and lighter than retracts, but not as realistic. Jim has successfully flown this model without the skids, but the minimum skid length required for reliable takeoffs has not been determined. They shouldn't be too long, or they will cause excessive drag during takeoff.
Typical balsa fuselage cross sections are included on the plans as an aid to wood construction. A sketch of one possible building method is also shown. The curved upper and lower parts of the fuselage can use planked construction or formed balsa blocks. Form the engine compartment with balsa blocks or epoxy and fiberglass covered foam blocks.
If the above is not too clear, it is suggested that the reader refer to the author's Firecracker FAI racer article in the January 1972 issue of AAM. A complete discussion of a wooden fuselage is included. If a fuselage is constructed from scratch, it is important to note that the minimum width and height (occurring at the cockpit on this model) must be 3-3/8 in and 6-15/16 in. The basic fuselage is 2-1/4 in wide, with the extra width occurring only in the fairing above the wing.
Construction. If a fiberglass fuselage is used, the first step is to file a Tatone No. 3 mount to fit. The front end must be filed somewhat to fit within the fuselage. Depending on the engine, the engine lugs may also have to be narrowed. An HP will fit with a minimum amount of material removal. The ST G-40 requires quite a bit of filing.
For maximum adhesion, polyester resin should be used to bond the fire-wall and bulkheads to the fuselage. Use a fillet of glass matt or micro-balloons, mixed in resin for reinforcement. The front wing mount bulkhead should be drilled for the 1/4 in hold-down dowels before it is installed in the fuselage. The mating 1/4 ply plate, which is later glued to the front of the wing, should also be drilled at this time, to insure that the holes match. However, the aft wing mount should not be drilled and tapped until the wing is completed. Note that the rear wing hold-down is bonded and screwed to the aft bulkhead before installation in the fuselage. A layer of fiberglass cloth on each side of this hold-down will insure that the tapped hole will be durable..."
Phony Folkerts, American Aircraft Modeler, July 1974.
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Article pages, thanks to RFJ.
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