Petrel (oz10623)

About this Plan

Petrel. A/2 competition glider. World Championship winning design.

Quote: "Petrel. Reigning World Glider Champion BABIC SLOBODAN presents his winning design exclusively for MA readers.

WORLD Championship class A/2 gliders are, without doubt, the most graceful looking of all contest models, and Petrel is certainly no exception to this rule. Of its performance we need only remind readers that flying the original, designer Babic Slobodan, won the World Championship in Czechoslovakia last year, with a perfect five-flight score of 900 sec.

This being an out and out contest design it is not anticipated that anyone without sufficient experience to interpret the plans will attempt to build it, so the usual building instructions are unnecessary. However, there are one or two points that should be borne in mind.

Firstly, the total area is somewhat under the maximum permitted by the A/2 formula, and also the original model was very slightly (about 1/2 oz) over the minimum weight. Neither of these two things (obviously) affected the performance, but they did make absolutely certain that there were no queries likely to arise during processing.

The final trimming of the model determines whether it will be a potential contest winner or just another 'also ran,' and this cannot be carried out too carefully. It is essential that the CG be exactly in the position shown on the plan, and this must not be varied. Trimming adjustments are made by altering the tailplane incidence, as the wing incidence is fixed and must also on no account be altered.

Trim the model to fly in a 150-200 ft diameter anti-clockwise circle which will enable it to take advantage of any slight lift that is about. The auto rudder will take care of the tow, but be careful when releasing the model from the top of the (nylon) line, that it is biassed into this anti-clockwise circle, for if it is released straight it may refuse to take up its natural turn and just stall down in a straight line.

Provided the foregoing points are watched, you shouldn't have any trouble in reaching World Championship standards (or will you?) but anyway, the best of luck."

Petrel, Model Aircraft, September 1958.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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