Student Lessons & Information
Hello All,
This Page is a work in progress as always suggestions are appreciated. The PowerPoint's are all uploaded as well as quick reference links. Also, here are some great videos to get you started; most are from Robinson Helicopter Company. They are free of charge on Robinsons website, but they are a little more "out of the way" so they are linked below for your convenience. Also, don't forget to grab yourself a copy of the R22 POH linked HERE
or the R44 POH linked HERE
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Symmetrical and Asymmetrical Cont.
•Symmetrical airfoils has the same upper and lower surfaces.
•Asymmetrical or Non-Symmetrical airfoils has Different upper and lower surfaces
•Symmetrical airfoils are less costly to build
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•Asymmetrical or Non-Symmetrical airfoils are more costly to build
•Asymmetrical or Non-Symmetrical airfoils have better lift to drag ratios
•Symmetrical airfoils because of there shape the center of pressure remains constant under varying angle of attack
•Asymmetrical or Non-Symmetrical airfoils as the angle of attack changes the center of pressure shifts and causes a twisting motion to occur
•Note Asymmetrical or Non-Symmetrical airfoils, new materials and new design processes have over come many of these road blocks
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•The twisting motion that is mentioned above. Think of it like a credit card how many times can you bend it before it breaks? The answer I'm not sure but it does have a limit.
•Now think of your rotor blades in the case of an R22 they are passing a given point about 9 times every second. And as you will learn it the coming slides they flap and move all the way through the 360° of the orbit and they do this 9 times a second.
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•How much flexing do they then do in an hour?
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•The engineers have to account for this and essentially engineer a credit card that has billions of flexes in it before failure (this is the challenge with Asymmetric airfoils and also why the “economical” Robinsons use Symmetrical airfoils
