What I have done with foam gliders I think is a good example of taking an idea and expanding on it in many ways. After building and flying the FPG-9 glider I got to thinking how can I expand on this? How can I make it fly longer and look better while still using mainly foam plates as the building material.
My first experiments were in trying to improve performance. My approach was to reduce the weight of the FPG-9 and I looked first at where weight could be eliminated in the glider. The obvious choice there was to reduce the amount of weight in the nose needed for balance which was a penny. To do that, I extended the nose out with a straw and used a smaller weight at the new nose. The FPG-9 was now lighter but it really didn’t seem to glide any farther. How could that be, I think that could because there was still just as much drag and there was less kinetic energy to pull the glider along the glide slope. My next variation on the FPG-9 idea was to make a better looking glider, I wanted it to look like a jet. I also wanted to improve the performance by creating a glider that could be catapult launched with a loop of rubber strip. I built a couple of prototypes from balsa and then built a foam glider of similar outline. In keeping with my choice of building materials I came across another common issue, constraints. By using the foam plate material I was limited to the size the glider could be built. My solution was to splice the foam together. I knew this would not be strong enough so I covered the wing top and bottom with tissue. It did not take many launches and the wing started to buckle in one spot. I repaired this by using some clear tape.
On my next foam jet glider I would try to improve the strength of the wing and improve the glide ratio of the glider. I did this by putting a bend in the wing which makes it stiffer and gives it a better airfoil than a flat wing. From the start I put plenty of clear tape on the wing for strength and eliminated the tissue covering. This glider flew pretty well, looked sharp, and the wing held together. It just seemed like too many pieces and too much work to build.
That is when I came up with the Hammer Down Catapult Glider. By using the foam from a meat tray for the wing, I was able to create two wings from a single meat tray using foam that was thicker. The fuselage would be made simpler by using a small pod in front and a boom from a bamboo skewer. I created “sort of an airfoil” by compressing the foam starting at mid-chord of the wing by beating the foam with a hammer. The negatives to this plane were you had to find the foam meat trays and it was a fair amount of work cutting the sides off the foam tray. This brings me to the current foam planes which I am creating using foam plates which can be purchased and plastic straws. I have been using the larger and longer straws found in restaurants most of the time. I plan to try the straws common in grocery stores too. It is possible to splice straws together by squeezing one end and shoving this into another straw. The plane is built from three 9” diameter foam plates, straws, and held together with masking tape. The wing goes under the straw which makes for a stronger joint for wing halves but you have to hold the straw behind the wing to launch. I have also been experimenting with catapult launching these gliders with some success. At times I get good launches and glides, other times the glider arcs into the ground. Adding some masking tape to the leading edge of the wing has helped some. No doubt something is flexing during the stresses of launch causing the plane to dive. Bill Kuhl
Foam Plate and Plastic Straw Gliders article
Rubber Powered Foam Airplanes article
Basic Aerodynamics With a Lesson article
Video of Amazing flight of rubber powered foam plate & straw airplane