Squirrel Design Choices. Why is the Squirrel a Better Model Airplane?
Squirrel was designed by Darcy Whyte using design methodology from the software industry. This unique upbringing included extensive research and testing resulting in a highly improved model plane that is now enjoyed world wide. It’s accessible by beginners and can perform well enough to be loved by experts too. In fact the model is a platform for experts to share model aviation with their friends.
1) No tools required! All you need is glue and scissors. Traditionally model airplanes that fly well need many tools it’s difficult for children and for classrooms. They need a hobby knife, pins, cork board, printed plans, cellophane wrap, needle nose pliers with cutters, sand paper and more. In a classroom environment this is a lot of risk and a lot of logistics.
2) Dihedral and polyhedral were dropped in favour of winglets. The dihedral angle in a traditional model airplane is a point of failure since there is a glue joint in the center of the wing which is bears the weight of the airplane. It is also very complicated to assemble.
The new system is remarkably easy to assemble and is surprisingly robust because the tissue paper enforces the winglets. A dab of hobby or white glue and the winglets can be glued while other work is in progress. The winglet joints are not exposed to lift stress and the right angle is easy to set.
3) Leading Edge Only (LEO) for stabilizers. This simplifies construction drastically and forms a rear bumper. When the plane hits the wall or the dog and falls, the rear stabilizers don’t break because the rear motor stick hits the floor before the stabilizers.
4) Build Onto Tissue (BOT) consolidates steps. This idea was borrowed from the famous AMA Cub design by Frank Ehling in 1967. (AKA AMA Racer, MAAC Cub). The Squirrel is simplified a step further by using only right angles so that no printed plan is needed. It takes less than 1/4 the time to build a Squirrel.
(Photo’s courtesy of Rolf Christophersen, Germany).
5) With its removable wing it is not only adjustable but several can fit in a shoebox. This increases the survival rate of the model amongst children and pets. There is a wing handle so that when the wing is removed the elastic band fastener does now fly away but instead is captured by the handle. The wing can be idled forward and backward to change the climb characteristics of the model.
6) The wing is covered on the bottom to speed construction. The leading edge therefore acts as a turbulator and appears to increase the efficiency. Many traditional modelers think this is wrong so this improvement was not discovered until it was tried. For the small size, low speeds and modest angle of wing incidence turbulence can be constructive. This is because the Reynolds number (see fluid dynamics) is low and the viscosity of the air rules over other properties in these circumstances. Nature tells us this secret in the flight of the bumble bee.
7) DIY friendsly. All parts cut out of 3×36″ sheet evenly with no waste. All parts are straight so cutting is fast and easy. Workshop preparation is trivial. No cutting is required during workshops because all parts are easily pre-cut.
8] It is very stable and looks very unusual when its flying because of the strange winglets. It has proven to be a show stopper.
9) No music wire. In order to remove the need for music wire, wire cutting, bending and fastening, the traditional wire hook for the rear motor hanger has been dropped. A toothpick is used instead. This works extremely well and can serve as an anti thermal device since the elastic can drop when unwound.
10) The use of a glue stick as well as white craft glue speeds construction considerably without adding any toxic chemicals. Also the glue stick doesn’t add water to the leading and trailing edges (like white glue) and it is less prone to warping and does not need to be pinned to a building surface!
