Clipper Chisai (oz14264)

About this Plan

Clipper Chisai. Free flight power model, for PAAload competition.

Quote: "From far-off Tokyo comes a new contender for PAA-LOAD honors designed by the man who originated Pan American World Airways' model event. Clipper Chisai, by Dallas B Sherman.

When word filtered through from Tokyo that Dallas B Sherman, the poppa of Pan American World Airway's PAA-Load event, had designed a, model for the '51 payload competitions, great interest was evidenced over what 'ole DB' had produced.

Here is the outstanding PAA-Load design by the man who dreamed up the event. It has been successfully flown by various Japanese modelers and comes in time to make the US meets this summer. Mr Sherman's own comments on the model follow:

Wing, stabilizer, and rudder are entirely conventional and need no explanation beyond the drawings. They may be covered by materials at the builder's option. We used silk because it is cheap and plentiful in Japan, and adds strength. The frame structure is strong enough to take it. Test flights have indicated no changes at all that should be made in these surfaces.

The fuselage is a little different from the run-of-the-mill. In design, it is an attempt to get the rectangular section required for the PAA-Load 'occupant' and at the same time 'fade' the re-mainder fuselage into a shape more streamline at the high angles of attack at which the model actually flies. It is assumed that a free-flight model in competition never actually flies 'level' and therefore 'straight line' streamlining is of little or no real merit. More effective 'climb and glide' streamlining of the fuselage is theoretically possible, but here we compromised for structural simplicity and lightness plus a deepened belly to assist in anti-spiral characteristics.

In building, construct the crutch first. Leave the crutch on the working surface and build on the bottom of the fuselage inverted. The top of the cabin may be built separately and glued on as a unit. Then fill in the top fuselage structure from cabin back to front of stabilizer position. Note that the landing gear is installed while fuselage is being built in order that the lower center nose brace may be attached to the landing gear ply-wood mount.

A desirable refinement is to trim all of-the intermediate tri-angular bulkheads to concave shape; this gives a more pleasing cover appearance by preventing the cover from sticking to the bulkheads and also cuts some structural weight. Silk covering is recommended for the fuselage because of the curved-to-flat transitions in-volved and also for strengthening purposes.

The 'paper or thin wood' cov-ered sections at front of fuselage were actually covered on the test model with 1/20 balsa sheet, which has proved satisfactory. Other fuselage details and procedures are routine practice. As expected, the crutch is sufficiently wide at the rear so that no stabilizer rest as such is required.

Decoration as shown on the drawings and photos is quite at-tractive and, together with the overall lines of the model, gives a most realistic appearance both at rest and in flight. It is pleasing to note spectators referring to the Clipper Chisai as 'that little airplane' instead of 'that model'. Generous hot fuel proofing is recommended.

The test model uses standard OK Cub .049 glowplug engine. No timer was employed, the engine run being determined by clocking full tank and releasing for flight with the desired number of seconds yet to go. (For tests in the small fields of Japan, we use 15 seconds ROG; a larger tank would be required for the US standard 20-second run). Propeller is a 7-inch-diameter, 3-inch-pitch broad blade type, with tips trimmed down about 3/8 inch each..."

Clipper Chisai, from Air Trails, May 1951.

Direct submission to Outerzone.

Update 25/9/2024: Added colour scan of the isometric drawing, thanks to dfritzke.

Supplementary file notes

Article pages, thanks to RFJ.
Isometric drawing.

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