ADVANCED: FPG-9 BUILD AND FLY

If possible, purchase a couple of balsa wood model plane kits from the Academy of Model Aeronautics (https://www.modelaircraft.org/shopama/dept.aspx?id=DA090A0104E24ABFA8C167BCE9633365). There is a balsa wood plane kit for under $10 (model 6110) that is a rubber band–powered propeller plane. (Model 6110 is the least expensive, but there are other rubber band–powered models on the site.) Have the participants assemble a few balsa wood models and compare the attributes of the FPG and a powered plane. Ask: Which plane flies longer, the powered or the non-powered plane? Do you think the plane’s material (Styrofoam versus balsa wood) makes a difference? How do you think these two factors (powered versus non-powered flight and construction material) translate into real-life considerations for airplane design?

Discuss why the FPG-9 plane can fly so well if it’s not rounded like an airfoil. Ask: Are there real-life planes with airfoils that are flat like the FPG-9? What are they? (Real-life planes have very thin but not completely flat airfoils. The F-105 jet and century series jet both have thin airfoils.) Also, point out that if you push a barn door fast enough and with an appropriate angle of attack, it will generate some lift. It won’t fly efficiently, but it will “fly” in that it is a controlled fall. Explain that there are two halves of the lift equation (lift and gravity/weight). Enough thrust will help lift overcome gravity, at least temporarily.

Discuss wing shape. NASA has a resource about wings titled “Foam Wings” at https://www.nasa.gov/stem-content/foam-wing/. There are a number of other resources on the website that may interest your participants. NASA offers other educator resources at https://www.nasa.gov/audience/foreducators/index.html.

Ask: What components of the FPG-9 are essential? Can it fly, for example, without the penny? Without the tail? Discuss why. (The penny is needed for weight and balance. Weight at a height is potential energy. The penny provides control for the center of mass. It shifts the center of mass forward, which gives the plane speed and balances the tail. Without the tail, the plane would not fly straight.)

Explain that elevons are a combination of ailerons and elevator. Ask: Are there real-life planes designed like that? What are the advantages or disadvantages of having two moving parts versus one? (The B-2 stealth bomber is designed this way. It is more efficient because fewer surfaces means less drag, but it is also less stable. It’s like a teeter-totter. A wide but short plane has the forces close together so it’s more difficult to make fine adjustments in flight.)

If your group designed a plane in the aerodynamics activity, how does the FPG-9 compare with the one you created in aerodynamics that also has thrust? Which is faster? Why? Which seems more stable? Hold a race to find out.