07 Mar
RC airplane site strictly created to feed your addiction.
Aerodynamics: To fly, an airplane’s wing has to overcome gravity by developing lift greater than the weight of the plane. Since it can’t do that standing still, airplanes use thrust…force directed backwards…to drive the wing forward through the air and generate lift. However, thrust has its own opposition to overcome in the form of drag—the resistance of the air to a body moving through it. If lift and thrust are greater than gravity and drag, you have the potential for flight…and fun.
Wing Location: Wing placement, for the most part, falls into two major categories—high wing design and low wing design. In a high wing design, the weight of the model is suspended below the wing. When the model tilts, the model’s weight tries to return it to a level position. As a result, high-wing models tend to be more stable, easier to fly—and natural choices for trainers. A low-wing model is just the opposite. With its weight above the wing, it tends to be less stable—excellent for advanced fliers who want to perform rolls, loops and other aerobatic maneuvers.
Airfoil: If you face the wing tip of the plane and cut it from front to back, the cross section exposed would be the wing’s airfoil. The Flat-Bottom Airfoil will develop the most lift at low speeds and helps return the model to upright when tilted. This is ideal for trainers and first-time pilots. A Symmetrical Airfoil’s top and bottom have the same shape, allowing it to produce lift equally whether right side up or upside down and to transition between the two smoothly. This is recommended for advanced pilots. Lastly, a Semi-Symmetrical Airfoil is a combination of the other two and favored by intermediate and sport pilots.
Wing Area/Wing Loading: Wing area is the amount of wing surface available to create lift. Wing loading is the weight that a given area of the wing has to lift and is usually measured in ounces per square foot. Generally, a light wing loading is best for beginners. The plane will perform better and be easier to control.
Dihedral: Dihedral is the upward angle of the wings from the fuselage.Dihedral increases stability and decreases aerobatic ability.
Wing Thickness: Wing thickness — measured from top to bottom — determines how much drag is created. A thick wing creates more drag, causing slower speeds and gentler stalls and is ideal for beginners. A thin wing permits higher speeds and sudden stalls — desirable for racing and certain aerobatic maneuvers.
Landing Gear Location: Tricycle gear includes a nose gear and two wing (main) gears, making takeoffs and landings easier—ideal for beginners. Continue reading
The following was written by Dick Kline, inventor of the Kline Fogleman airfoil. Dick has graciously written this great piece for all of us. Thank you Dick!
I have been asked a number of times, “How did you come up with the Kline-Fogleman airfoil?”
Back in the early 1960s, I was working as an art director for an advertising agency in mid-town Manhattan. My office was on the 24th floor, overlooking 42nd Street, the New York Public Library and Bryant Park. I had no knowledge of aerodynamics back then, but I loved to make paper airplanes and would occasionally sail one out the window and watch it fly over the park and the library.
On weekends, I would take my young son out to a ball field to fly paper planes. But it could get windy outdoors, and the paper airplanes couldn’t handle the conditions very well. I couldn’t throw them very
hard without having them collapse. So I asked myself, “How can I make a paper airplane that I can throw hard into the wind, have it climb up and when it reached the apogee automatically level off by itself and go into a nice long glide?”
Once you pose a question to your mind, it will begin to work on the problem. You will get impressions – often visual – that suggest you try this or try that. One of the first things I tried was to make a more-rigid paper airplane – one that could stand up to a strong throw. By making an extra fold on each wing running from leading edge to trailing edge and then taping them tightly together, I created a fuselage. This made the paper plane much stronger, and the wings held together even with a hard overhand throw.
But I still wasn’t getting the height that I wanted. I could see it happening in my mind, but not in the real world. Then one day, I looked at the extra fold of paper that one makes when first folding a paper airplane. This is done because you want more weight up front to carry the plane forward. I opened up the folded-over piece on each wing, creating pockets. Now each wing had a step about half-way back from the leading edge on the underside of the wing. I gave the plane my best pitch. It took off directly into the wind and climbed up about as high as a telephone pole, then leveled off and went into a nice long glide. That’s exactly what I was looking for. It’s what I had imagined. Mind you, this did not happen overnight. It took many attempts until I was able to get it to perform the way I wanted it to. For example, the depth of the steps on both wings had to be equal . If one step was deeper than the other, it would affect the flight, and the plane would not fly straight and true. Or, if the folds did not meet where the fuselage started in exactly the same position on each side, it would also cause the plane to fly poorly. I had probably made over 100 paper airplanes before finding my solution. Equal pockets on both wings and perfect alignment of both wings. That combination made for the perfect flight.
For the next four years, I tried to interest toy companies, but without success. Then, one day a photo-retoucher who was doing work for me came into my office. Floyd Fogleman was a pilot and model-airplane builder as well as a retoucher, and I gave him a demonstration of my paper airplane, launching one down the hallway. He went running after it and came back, saying “I think you’ve got a whole new concept in aerodynamics here.” He noted that the paper airplane appeared not to stall, but continue flying and was extremely stable in flight. We
decided to apply for a patent after he took one of the planes home and translated it to balsa wood. It flew with the same characteristics as the paper models. Two years later, we had our first US patent, #3,706,430.
I now believe that every discovery starts with a question. Imagine some guy – maybe an accountant – in an office a long time ago. And he made mistakes as he wrote down his numbers. He was using a wooden pencil,
but was always misplacing his rubber eraser. He probably asked himself, “Why can’t I find that eraser when I need it?” One day, it occurred to him to put the rubber eraser on the end of the wooden pencil. Today, almost every wooden pencil comes with a rubber eraser on its end.
So if you want to begin an interesting adventure, start by making an observation and then asking yourself a question.
To make use of Kline’s Airfoil in your own project, here is a diagram below of the different bends of the foam to create the plan wings airfoil.