Wednesday, June 27, 2007

P30 - Ideal for Improvers

Did you enjoy building and flying your first rubber powered model? Are you hungry for more? A P30 class model may be the perfect answer. This class is a few decades old and is very popular. It suits the developing modeller and also provides a real challenge for experienced fliers. The rules vary slightly country to country, but in essence are:

1. Wingspan and overall length each less than 30 inches.

2. Plastic commercially available non-folding prop less than 9.5 inches in diameter.

3. Rubber to be enclosed within the fuselage.

4. Rubber including lubricant to weigh less than 10g.

5. Model without rubber to weigh 40g or more.

These things can fly! Two minute maxes are not difficult to achieve. Flyaways are common, so you need a good dethermaliser. The minimum DT is the pop up stab - see the photo at the bottom. While these are ok, they may be insufficient to bring the plane down from a strong thermal. More drastic DT is the pop off wing. The wing tip is connected with a line to the rear end of the fuselage. When the DT releases, the wing comes off. The fuselage hangs down and the wing spirals around as the plane descends.

These are photos of my first P30. It is based on the Roger Dodger design, but I could not help modifying it in various ways.

The photos also show a simple design for a "stooge". This is basically an anchor point to hold the plane while you wind the rubber with a mechanical winder. It is also advisable to use a "blast tube". Mine took 5 minutes to make out of a piece of 20mm plastic piping that I had lying around.

Below is a brief video of the model at the top of the power climb. It flew OOS on that occasion, but was later recovered (thank Hung I wrote the phone number on it!) That happened because I set too long a time period on the DT. Doh!

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