About this Plan
Zephyr. Control line profile stunt biplane model. Wing area 502 sq in. For 35-36 engines.
Direct submission to Outerzone.
Update 06/09/2020: Added article, thanks to JohnL.
Quote: "The Zepyr, by Raymond Zarichak. An easy to build profile bipe that'll draw a crowd wherever it's flown.
The Zephyr was designed primarily to fill the gap between the ordinary sport/ novice trainer and the beginner stunt ship. My desire was to make a sporty, 35-powered, ruggedly-built biplane using stock wood sizes and hardware carried by any local hobby shop, and capable of doing aerobatics. It had to be simple in design, be easy to build, and have no fancy hard-to-duplicate curves. Nearly all the lines of the Zephyr (with the exception of the wing ribs and forward part of the fuselage) are straight and easily reproduced on balsa wood with nothing more than a straightedge and X-acto knife.
However, I also wanted to incorporate a few unusual ideas, not normally found on ukie ships. which would lend them-selves quite favorably to a profile Bipe. The most distinctive feature is a fully adjustable, very strong control system that is also fully removable and fully visible. By being completely exposed, the system is easy to inspect and service, if necessary. I also wanted a strong, torsional, fully removable landing gear - one capable of taking the tough punishment of hard landings on the roughest terrain without damage. How many models have been ruined by a ripped out landing gear after a hard landing on terra firma, or the inevitable cracking, crunching and over-stressing inside the fuselage when straightened out by the unlucky flier?
A strong motor mount is a desirable feature on any model. The Zephyr's motor mounts are extremely long and therefore very effective in dampening the engine vibration which sometimes plagues profile models. (No stress cracks after a full season of flying - and two beautiful pilot-error stack jobs!) The long mounts also provide a firm tank mounting and a secure anchoring for the bellcrank plate. By adhering to my original design philosophy, the finished product has been the most consistent, trouble-free flyer in my aviation stable.
WING: The first step in constructing a straight and true wing is getting per-fectly identical ribs. This is easily done by stack-sanding them between two metal rib templates. Start by cutting the template pattern from the plans and glue it to one of two fairly heavy aluminum blanks with rubber cement. Clamp the two aluminum blanks together and carefully drill out the alignment holes with 1/4 in-diameter drill.
With the holes drilled, bolt the blanks together and file them to the exact curvature of the paper pattern outline. File out the spar notches. being careful not to file out too much, Check the notches with a spar as you progress to insure a snug fit. This might seem like a long drawn-out process, but its well worth the effort.
With a rib template, trace the correct number of wing ribs on sheet balsa wood with a felt tip pen. (Note that some ribs are 1/2 in sheet and some 1/16) Cut out the ribs. Again, be careful to trim them out oversize. When finished, take each balsa rib and position the metal template over it. Drill out the alignment holes with a 1/4 in-diameter drill or rotary file. Do this with every rib. Place two 3-in long, 1/4 diameter bolts through a metal rib. Then place the oversize balsa ribs on the bolts, enough for half a wing at a time. Put the second metal template on the bolts last. Tighten up the bolts. Now block-sand them with 120-grit production sandpaper until they are the same contour as the metal rib templates. Sand out the spar notches by wrapping sandpaper around the narrow edge of a small file..."
Update 06/09/2020: Replaced this plan with a modified version, thanks to JohnL. This is essentially the same plan, but some distortion on the wing rib template is now fixed, and there is a note re correct CG location.
Update 07/09/2020: Added missing page (p82) into the article file, thanks to JohnL.
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User commentsHi, friends. The complete name of designer is Raymond Zarichak.
Gabriele Macrì - 21/08/2020
Got it. Many thanks :)
SteveWMD - 21/08/2020
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