Bi-star (oz3930)


Bi-star (oz3930) by Ray Malmstrom 1973 - plan thumbnail

About this Plan

Bi-Star. Free flight rubber model.

Quote: "Delightful 18 in span rubber-powered sportster. Bi-Star, by Ray Malmstrom.

ALTHOUGH VASTLY outnumbered by the familiar monoplane, biplanes both model and full-size have an appeal and a glamour all of their own. Bi-star is no exception to this and combines the performance of a small duration-type model with the realism usually associated with a semi-scale job. So if you are looking for a bit of glamour (aeromodelling variety!) then stop right here, and grab that balsa-knife.

Fuselage: Cut out two fuselage sides from 1/16 sheet, noting the former slot shown in Fig.1. Add reinforcing pieces A, rear peg pieces B and 1/8 strip pieces at the nose. Lay over plan and build rear section of fuselage from 1/16 square strip, noting change of angle of top longeron at tail end - this is important as the tailplane is cemented to the extreme end of the fuselage and must be at 0┬░ indence to the centre (or datum) line (Fig.2).

Now construct the master former C from pieces cut from 1/16 sheet (Fig. 3). Cement the two fuselage sides to the master former checking carefully that the sides are upright at right angles to the former. Bring the rear ends together and cement. Add all fuselage cross-pieces (1/16 square) and nose cross-pieces (1/8 square).

Cut out nose formers D, E and F, and cement in position, adding the 1/16 square nose stringers. Now add lower nose reinforcing pieces G. Bend a length of 20 swg wire to form the undercarriage (this is best held in a vice) and then firmly bind and cement to 1/16 sheet piece H. Place 3/4 in diameter lightweight plastic wheels on axles and retain with small pieces of tightly fitting electrical tubing or a blob of cement as shown in Fig. 4. Cement the undercarriage assembly to fuselage (Fig. 5). Cover top of nose section and rear of fuselage, leaving open the lower rear bay for the tailwheel assembly, and section below rear peg, with lightweight tissue water shrink and give one coat of thinned dope (thinned 50/50 dope and thinner). Add thin cellophane or acetate sheet wind-screen and windows. Cut a length of 1/16 diameter hardwood dowel for rear rubber anchorage..."

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Bi-star (oz3930) by Ray Malmstrom 1973 - model pic


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User comments

A beautiful and typical Ray Malmstr├Âm design and very easy to build. I made a modification which did not affect flying duration of approximately 46 seconds. I decided to change the fragile 1.5mm square balsa rear section of the fuselage sides with a more strong section made from soft 1.5 sheet balsa. Best wishes from Colombia.
Eduardo - 02/06/2020
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