Naturally, you have to pay attention to incidences early in the design phase, but that's pretty basic stuff once you learn it in the first place.Naca airfoil lift drag. I have settled on just two stab airfoils, either a flat stab for non-scale sport planes, or the NACA 0001 for everything scale or giant size sport.įor wings, the Clark-Y gets the nod for anything non-scale and sport (and even considered for some scale designs), but my all time favorite for the wing is the NACA 2415, a relatively fat airfoil that overcomes the Reynolds numbers penalty of most scale full size wings when scaled down to a smaller size, but looks very scale on the aircraft.īecause the Clark-Y and the NACA 2415 offer great performance characteristics for model size aircraft, I really don't look much further than either of those for the wing. If you intend to do the STOL thingy, stay with a flat bottom airfoil. If you have a model airplane that suits your flying style, copy that airfoil.Ī heavy model should use a semi-flat bottom air foil (Clark -Y, USA 35-B).lighter models can move to semi-symmetrical airfoils. If you haven't yet, you might want to pick up one of the books on model aircraft design that would give you some ideas and suggestions and other good information about airfoil design. So first, you have to answer the question on whether you want to aircraft to fly slow and scale like, or do you want to be able to do some non-scale maneuvers and even aerobatics with your model. The Clark-Y is a semi-flat bottom airfoil that is most typically used for trainers, but it also works well for many scale projects I've seen. JT, don't get hung up on using the same airfoil as did the full scale aircraft because you will find that you will get trapped in a Reynolds numbers fight that you will lose.ĭavid mentioned the Clark-Y which is a great airfoil for general use, but there are also other airfoils that could work well depending on how you intend to fly the aircraft. Can anyone suggest a good airfoil for scale models of these aircraft? I then noticed that someone mentioned the Eppler E197 although this does not seem to match the airfoil shape shown on either the Hostetler BEAVER plans, or any 3-view drawings for the OTTER or BEAVER. Note that when building, you can order CNC foam wing cores for dozens of airfoils on line at places like FlyingFoam. (WWI planes have some very BAD flying characteristics, because they didn't know a lot about airfoil design.) The more you learn, the more interesting it will become. They fly more as if they were a "flat plate."īasically, if you design RC planes, you want to think about lift, drag, pitching, strength of design, speed at which the wing will fly, how it will stall. Short, stubby wings with a big cord (such as jets) with an aspect ratio of < 1.0 really don't care a lot what the airfoil shape is. Generally long, thin wings are more efficient (but harder to build for strength). The aspect ratio of a wing (length to cord ratio) is important. Sailplanes use airfoils with 8-9% thickness, but these are much too thin for powered planes. These are airfoils that allow changes to the shape, in flight (such as Martin Hipperle designs). The most advanced airfoil design in RC planes is in sailplanes built for multiple tasks (thermal climbing/racing). Thicker leading edges give more control, thinner ones make it more difficult to gradually change plane direction. Note that it is thicker than intuition would suggest. Selig designed the S6061 airfoil for RC pylon racing, and this is the airfoil used in the Quickie 500 Viper, still available as an ARF. NACA 14? airfoils are semi-symmetrical, and can work decently for planes that you might want to roll occaissionally (not trainers). The NACA 00? airfoils are symmetrical wings, that tend to work better for aerobatic planes. This is a 15% thick airfoil, and not symmetrical. 481 in the appendix) is a general purpose wing that works well at RC sizes. The appendices in this book has hundreds of airfoils, with cross sections and basic information (lift, drag, and pitching moments).įor basic flight, the NACA 2415 (p. The book "Theory of wing Sections" ($16) is a reprint of design theory of airfoils, for subsonic speeds. If you don't increase the amount of control surfaces in RC planes, you probably will not get the amount of control in maneuvering that a better design would give you. If you use the same airfoil as the full-sized plane, you will probably get much worse flight than you would have if you use an airfoil that is known to behave well for RC size planes. (Air doesn't automatically get 5 times thicker, if you build a 1/5 scale plane.) Look up "Reynolds Number". Full-scale airfoils often work badly for RC size planes, because the air doesn't get thicker, as you build smaller and smaller models of full-sized planes.
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