Skyfire (oz3521)

About this Plan

Skyfire. Free flight power pylon model.

Quote: "A ship Featuring sweot-forward, Waren truss wings and stabilizer, by Earl Cayton. Wingspan is thirty-seven inches with a five-inch chord. Although the original model was powered by an .049 Royal Spitfire, any .049 can be used.

The Skyfire is a very simple to construct 1/2A free-flight ship, with high performance and the ruggedness needed for contest flying. The glide is good for a 1/2A, and if you keep the weight reasonably close to the AMA minimum (100 ounces for each cubic inch of piston displacement), you will find that the Skyfire will climb straight up. Interested? Okay, let's start construction.

Although the plans are mostly quarter scale, the design is very simple and no elaborate drawing experience is needed. A pencil, a ruler, and length of wrapping paper are all you need to enlarge the plans to full size. Ribs and bulkheads have been drawn full size to save you time.

WING AND TAIL: The wing and stab are simple 'square-ender' design and the plans and pictures practically speak for themselves. You will notice that the wing and stab are swept-forward. There are all kinds of arguments, pro and con, about swept-forward and swept-back surfaces. However, our design is at least a departure from the monotonous routine of straight square surfaces that mark many of today's free-flight models.

You will notice that the wing and elevator are constructed with a Warren Truss arrangement. Although not new, this type of construction has been popularized of late by Dennis Davis in his famous Hogan (oz7420) series. It is just as easy to cement ribs at an angle as straight, and this angular placement of ribs greatly resists warping.

The rudder and sub-rudders are made from 1/16 quarter-grained balsa sheet. Add 1/8 triangular-shaped balsa fillets at the junction of the main rudder. Use plenty of cement, or better still, use Weldwood to glue the sub-rudders in place. Sub-rudders really take a beating.

FUSELAGE: The fuselage is very simple - it practically falls together. First, join the 1/16 balsa sides together at the rear, then fit the bulkheads into place. Next, cement the pylon together and then place it into position in the fuselage. Now, cement the 1/16 balsa sheet top and bottom into place, then add the wing and stab platforms.

Solder the engine mounting nuts to a piece of scrap tin and hold it in place behind the firewall with thin wrapping wire, soldered into place. Also, bind the landing gear to the firewall with thin copper wire, soldered for security.

Use Weldwood and gauze to hold the firewall in place. Weidwood is much stronger than cement and is hot-fuel proof. Use the 1/8 plywood engine backer. It will protect your engine during crack-ups..."

This plan was printed in Flying Models Decade of Designs (1), published 1960.

Direct submission to Outerzone.

Update 22/12/2018: Added article, thanks to RFJ.

Supplementary file notes

Article.

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