Radio Control: Giant Scale
Bob Beckman
IMAA International Fly‑In
International Miniature Aircraft Association's first annual International Fly‑In is set for September 25–27 at Tom Sawyer State Park, Louisville, KY. The site has excellent facilities for R/C flying. The Louisville R/C Club will handle organization and operation with assistance from IMAA Headquarters.
From the way IMAA has progressed this year, I predict this fly‑in will become the premier event in worldwide Giant Scale activity. For more information, write: International Miniature Aircraft Association, Inc. 254 Washington St., Binghamton, NY 13901
Quadra engine tests
The first installment of our engine test report appeared in the April issue. One of the engines we ran was a Quadra that we originally thought was an early/original model; after contacting the Quadra factory (Trail Manufacturing) we discovered the test engine was an intermediate version.
Trail has provided three different Quadra models for further testing:
- the original Quadra
- the intermediate Quadra with the "factory‑balanced" flywheel
- the latest Quadra version
In addition, Dario Brisighella has supplied one of his "overbalanced" flywheels. That will allow us effectively six series of test runs (three engine versions × standard vs. overbalanced flywheel). With favorable weather we plan to publish this installment in the July issue. The July issue will also include the report on RC Giant Scale at Toledo.
PT‑19 plans
One of the first Quarter‑Scale designs to gain wide recognition—especially on the West Coast—was the Fairchild PT‑19 designed and built by Jim Foline and flown by Lee Taylor. Plans have been available for some time, and I have seen several completed models around the country.
Key points about the model and the plans:
- Designed originally for the Quadra engine. Nearly every example I’ve seen has been Quadra‑powered and tends to be heavy for that engine.
- Plans list empty weight as "28 ± 5 lb." Builders report most completed models are at or above the upper limit.
- Wing area is 12.8 sq. ft., which at the reported weights yields about 2.5 lb/sq. ft. wing loading—high for an engine the size of a Quadra.
- Despite the weight, the design flies well, which speaks to its basic soundness.
Options to improve performance:
- Add more power (difficult if you require a completely scale appearance; many engines will protrude from the cowl).
- Build the airframe lighter (preferred where possible without compromising structural integrity).
Construction features and suggested weight‑saving modifications:
- Materials called out: basswood, plywood, and balsa (spruce can substitute for basswood in the fuselage).
- The conventional built‑up fuselage uses Lite‑Ply doublers and a firewall behind the trailing edge; balsa formers and sheet stringers complete the shape.
- Tail surfaces are removable.
- Wing: nine‑foot span broken into three sections (center section with landing gear mounts and flaps; two tip sections plug on). Center section secured with dowels and bolts; outboard landing gear secured with nylon screws.
Major opportunities to reduce weight:
- Reconsider the three‑piece wing. While convenient for transport, the join method and structure add significant weight.
- Replace solid basswood spars with hollow box spars (ash or spruce) with 1/32‑in. ply or balsa shear webs. These will be lighter and can be stronger than solid spars.
- Use foam‑core board instead of balsa ribs to save weight and cut wing cost.
- Do not alter the airfoil shapes or washout—their geometry is the key to the plane’s good flying characteristics.
- Update hinge hardware: the original plans use a plywood tab mounting system for nylon/metal‑pin hinges; modern hinges (available from C B Associates and others) eliminate the need for the extra plywood tabs and save weight.
Notes:
- The plans were drawn in 1978; some construction workarounds used then have simpler modern alternatives.
- These comments are not meant as negative criticism; the plans are well done and flight‑proven. I would not recommend them for a beginner, but an experienced modeler should have no trouble producing a successful model with or without the suggested modifications.
Plans available from: Taylorcraft, Ltd. 216 Willow Ave., Roseville, CA 95678 Price: $28.00, postpaid
East Coast regional fly‑in
Planning is underway for the First Annual East Coast Giant Scale Fly‑In at Fort Meade, MD. The event will be IMAA‑ and AMA‑sanctioned and hosted by the Meade Modelers R/C Club. Tentative dates are October 10–11. More information and firm dates will follow as planning progresses.
Engines to be tested
Since the first part of "Big Bangers" in the April issue, many readers have asked about additional engine tests. What appeared in April was only the beginning. In addition to the Quadra series mentioned above, we will test and report on every engine we can obtain. Engines on hand or planned for future reports include:
- Mag Aero 1.2
- Homelite 1.6
- Elva 1.9
- Husky 2.0
- Husky 2.3
- Kawasaki 3.15
- Roper 1.9
Later in the year we will also look at one or more custom conversions of engines in the 3 to 6 cu. in. range.
Transcribed from original scans by AI. Minor OCR errors may remain.
