Interesting, I am sure that you built and flew a Tenderfoot model before you found fault in it. The two models it is based on is a Goldberg's "Glo-Bug" and Walt Musciano's trainer in his book "Building and Flying Model Airplanes". Both of these designs are very old designs and the engines that were in use then, were not as powerful as the ones we have today. The big advantages in this model is low cost, easy building and very sturdy. Personally I feel that a 1/2A model makes a much better trainer as it is not intimating for new flier.
Larry
Black Hawk Models