Educator (oz8114)

About this Plan

Educator. Radio control sport trainer. For .40 - .45 power.

Quote: "Educator by Justin Cork.

What's in a name - everything, it identities a person, a location, or an item. It is for this reason that I took into consideration a name that would be appropriate for this model. the 'Educator.' Meaning, that by the time the modeler with limited experience has built and flown this model he will have a good basic education on the subject matter. After having built numerous training and sport models. I felt that they all had some characteristics that were missing. The Educator as presented is the final refinement of numer. ow models I have built in this series. I believe that it is important that the potential builder of the model understand why I have designed the aircraft in the manner I have, in order that he may come to his own conclusion.

Most sport trainer designs that I have seen are a cosmetic rearrangement of another design. What I mean by that is the wing section is symmetrical, tail section is flat, and incidences are set at 0°. The engine is also set at 0° down and right thrust. This is a good starting point for a pattern model but hardly satisfactory for a sport trainer. Much better is the set-up often used by the scale modeler, a semi-symmetrical wing section, wing incidence at 2° negaitive, and tail plane set at about 1-1/2° positive. Where this arrangement really shows up is in the landing aproach where inexperienced fliers have the most problems. The wing at 2° gives additional lift at low speed and the tail plane at positive incidence keeps the tail plane flying, making for a low speed landing approach. 'The former set-up would stall and snap roll under similar circumstances. I also believe sonic engine right thrust should be used as models have a tendency to swing left on take-off, particularly taildraggers. Add a small amount of down thrust just for assurance that the thrust is in the right direction.

The first decision that has to he made is, what engine do you intend on using, not with regard to make, but to weight.

For the Educator I have selected and used two engines, the Fox 40 BBRC and Fox 45 BBRC, as typical of the type of engines one would use. From Clarence Lee's articles in this magazine the weight with muffler and spinner is 12.2 oz and 16.9 oz respectively. This required moving the fire wall forward 1" if the .40 size engine is used instead of the .45. Which engine do I prefer? If one has limited experience I would use the .40 as it will give you a lighter wing loading and has more than adequate power. The .45 if you want to get into pattern and scale for your next plane..."

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