Squirrel is a Better Model Airplane

Simple enough for school projects.
Simple enough for school projects, classrooms, cubs, scouts and community centers.

Short answer:

The Squirrel is simple and safe. It’s a great flyer.

It’s so fun you don’t even know you’re learning about flight and nature.

Long answer:

  • Less parts and less steps for assembly. The steps are easy.
  • It’s a safe, slow-flying, light weight model at about 10g (1/3 oz).
  • It performs well. In fact the model is a platform for experts to share model aviation with wider audiences such as schools, cubs, scouts and friends.
  • No tools! Made with just glue and scissors. Traditional model airplanes that fly well need a hobby knife, t-pins, cork board, printed plans, cellophane wrap, needle nose pliers with cutters, sand paper and more. In a classroom environment this is risk and a lot of logistics.
  • All parts cut out evenly from standard balsa sheets with no waste.
  • Dihedral and polyhedral were dropped in favor 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. Dihedral wing angles are also very complicated to assemble. The new system is remarkably easy to assemble and is surprisingly robust because the tissue paper enforces the winglets. The winglet joints are not exposed to lift stress and the right angle is easy to set.

    Winglet construction (photo courtesy of Rolf Christophersen, Germany).
  • Leading Edge Only (LEO) for stabilizers. The fin and tailplane have a balsa leading edge but not on the side edges or trailing edge. This simplifies construction drastically and results in a rear bumper. When the plane hits the wall or the dog and falls, the rear stabilizers don’t break because the tail-boom stick hits the floor before the stabilizers.
  • With its removable wing it is not only adjustable but several can fit in a shoebox. The wing can be idled forward and backward to change the climb characteristics of the model.This also 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 not fly away but instead is captured by the handle.
  • Build Onto Tissue (BOT)consolidates steps.  The Squirrel is simplified a step further by using only right angles so no printed plan is needed. So the parts can be glued directly to the tissue rather than framing up the parts then gluing to tissue later.  This idea was borrowed from the famous AMA Cub design by Frank Ehling in 1967. (AKA AMA Racer, MAAC Cub).

    Build on tissue (photo courtesy of Rolf Christophersen, Germany).
  • 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 and it was never tried. So Squirrel is the first model with this feature. 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, the maple seed and other insects.
  • DIY friendly. 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.
  • It is very stable and looks very unusual when its flying because of the strange winglets. It has proven to be a show stopper.
  • 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.
  • 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!