Cobra (oz9582)

About this Plan

Cobra. Radio control pattern plane, for .40 power.

Quote: "The time has come to challenge the supposed superiority of the 60's. Instead of scaling down the successful pattern ships of the past and designating them sport/pattern models, the time is right for a 40 powered acrobatic airplane, designed from the ground up, that will successfully compete in today's pattern contests. The Cobra is offered as just such a design concept.

Areas where a smaller pattern airplane is superior to its larger brother are immediately obvious. The cost of building and finishing materials, engines and fuel, are close to doubled for a 60 ship, when compared to an equivalent 40 size model. The problems of storage and transportation are noticeably reduced for the smaller airplane. It also pays not to overlook the difference in loss incurred after one of those inevitable 'radio failures'.

On the reverse side of the coin, many current 40 size designs lack smoothness in the execution of maneuvers. Some of this is due to design and can be improved, as I will discuss later, and some is due to technique. A 5 pound pattern airplane exhibits a smaller opposing force to a change of direction than does an 8 pound airplane, a fact which must be accounted for at the transmitter by avoiding quick stick movements. Control inputs must be introduced and removed smoothly. What this all means is that a flyer accustomed to 60 ships needs to fly the new 40's more than a few times to make the transition properly and to pass fair judgement on their capabilities. It isn't more difficult, just different.

A second criticism of the 40 is that its wind penetration isn't up to par. Admittedly this is the smaller design's weakest point, but much can be done to bring the wind performance within acceptable limits. The most effective adjustment available is wing loading..."

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