Princess (oz1824)

About this Plan

Princess. Control line aerobatic model for 1-2.5cc power. April 1959 Aeromodeller. This is a zipfile with the original article and drawing, and a modern redrawn plan in PDFvector format.

Quote: "Super-detailed plans for this elegant design which has an enviable reputation for smooth flying on low power. Princess, by Gordon Cornell.

PRINCESS is one of the most advanced small stunt designs to date, and has been developed through a series of designs capable of completing the SMAE Stunt Schedule. The plans show the very latest version as flown in the World Championships at Brussels, 1958, where it earned plaudits for very smooth performance with such a comparatively small engine as the Frog 150. Whilst its appearance might suggest a difficult model to build, its construction is relatively simple making it eminently suitable for the intermediate modeller and since the plans are very comprehensive, let's get down to the facts that will make your model a success.

Almost any 1 to 2.5 cc engine is suitable, the originals have been powered by the new Frog 150R and a K&B 15. If you choose to use 1 cc keep the weight down to approximately 13 oz. The tank may appear unconventional but it is theoretically correct; when a few more modellers use this type we will see far less overruns due to the engine leaning out - it gives most consistent feed in flight. Make the cowling exactly as shown on the plan giving plenty of airspace around crankshaft and cylinder, otherwise you will have the over-heating troubles I experienced at Brussels.

A brief word on materials, select each piece carefully for the job it is to do, making sure it is the correct cut and texture as stated. Since balsa varies in weight from 6 lb to 16 lb per cubic ft, here is the difference in weight between being light or heavy. There is a lot of balsa in this model, be careful. Use plenty of cement, it does not weigh enough to cause concern, at least not measurable.

When finishing, do not spare dope and fuel proofer since this little extra weight soon pays off. An under-doped or unproofed model soon suffers from ingress of fuel and up goes the weight above the well-finished model, at the same time becoming completely unreliable. Spare no expense, it is cheaper in the long run.

Flying the Princess is easy, but do not take any chances. The undercarriage shown on the plan is for grass, if the model is to be flown over tarmac fit a longer tailwheel assembly to make model sit almost level on ground (this tailwheel assembly will not allow the model to take off on grass so choose warily). Line length required will vary according to weight and speed should be between 45 ft to 50 ft. (It was flown in the Gold Trophy on 55 ft lines.) Use only steel lines .008 in to .010 in diameter. Use a good commercial grade of fuel and retain the same engine settings for starting and running for every outing, by so doing you will soon find reliability.

The plan has been specially drawn to cope with a wide variety of engine sizes and has run instructions to enable the modeller with at least one controline type under his belt to follow the building stages without cause for query. We know the Princess is going to be a number one favourite among plan builders with the popular AM.15, Frog 150 and newly introduced (to British shops) Enya, Fox and 0515's.

For smoothness, the Princess is a beauty deserving of its regal name as you'll soon find out in that first exciting lap."

Supplementary file notes

Planfile includes article.

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