Most people seem to think they are for increasing lift and reducing stall speed. \u00a0These are\u00a0real effects, but they are not the main reason to want flaps.<\/p>\n
Given this misconception, plus the fact that it requires effort to install flaps on an airplane, most RC pilots don’t fool with them. \u00a0If flaps are mentioned in a conversation about Telemasters, Kadets, or other slow planes with high lift and a flat glide, the thing you usually hear is “That plane doesn’t need flaps” because if the purpose of flaps is to increase lift and reduce stall speed, a Kadet already has high enough lift and a low enough stall speed.\u00a0 But this misses the point.<\/p>\n
What flaps\u00a0really are for<\/strong><\/span><\/p>\n Flaps are a high-lift device that have two major effects, plus some other side effects. \u00a0The major effects are to decrease airspeed and to increase glide slope angle when landing. \u00a0The side effects include the aforementioned lowering of stall speed and increasing lift, in addition to reducing the likelihood of tip stall, and possibly changing the angle of attack and thus the required elevator trim setting.<\/p>\n Imagine that you have a Kadet, or a Telemaster, or a primary trainer, or an old timer. \u00a0Your runway is not very long, it may be bordered by tall trees, or maybe there is a power line nearby or a street that you don’t want to fly close to. \u00a0Your plane has a long, flat glide, and it just doesn’t want to come down. \u00a0Instead it just glides along a few feet off the ground and uses the entire runway. \u00a0Flaps will decrease the airspeed, decrease the stall speed, and greatly increase the angle of descent, which will allow an accurate landing on a short runway.<\/p>\n Let’s get back to the common notions of scalar qualities that I mentioned in the second paragraph above. \u00a0Generally if you say that you’re going to fly a slow plane with a flat bottom wing, some folks will say that you’re going backwards as a hobbyist. \u00a0Then if you say you are going to equip it with flaps, some folks will say that the plane is already slow enough. \u00a0“It doesn’t need flaps.” \u00a0I wish I had a nickel for every time I heard that. \u00a0In a philosophical sense it’s true that you don’t need flaps, because you need them about as much as you need a model airplane in the first place, which is not at all because it’s just a toy. \u00a0But if you think of model aviation as an exploration of engineering combined with the pursuit of skill to execute various maneuvers, flaps are quite a nice addition to any plane with an excessively long, flat glide slope when you’re trying to land it on a small runway.<\/p>\n Should you include flaps in your next building project?<\/strong><\/span><\/p>\n You might want to try flaps some time\u00a0if you like to fly and you want to explore new possibilities, or if you like to build new things, or both. \u00a0If you have a heavy wing loading,\u00a0or if you have a very light wing loading, there is a possibility of running out of runway. \u00a0In both cases, flaps will slow the plane down, make it come in at a steeper angle, and allow you to use a shorter runway.<\/p>\n Different types of flaps<\/strong><\/span><\/p>\n You can use basic trailing edge stock to make plain flaps. \u00a0On any plane with strip ailerons you can cut the aileron in half, and use the inboard half as a flap. \u00a0This is good, but there are better designs.<\/p>\n If you want to get a bit more involved, check out the Guppy<\/a> plan on Outerzone. \u00a0This design requires you to create a separate trailing edge in the vicinity of the flap. \u00a0It’s more complicated, but with a little bit of foresight it doesn’t have to be difficult. \u00a0This type of flap is quite effective and would satisfy most people’s curiosity. \u00a0I’ve had a lot of fun with plain flaps.<\/p>\n Split flaps are easier to build. \u00a0Add a 1\/16″ ply panel to the bottom of the wing, hinged at the front with covering film. \u00a0Check out the Cloud Niner<\/a> plan and article on outerzone to see how these are built and used. \u00a0This is the draggiest flap, and it will really slow your plane down.<\/p>\n For a bit more lift and less drag, build a slotted flap. \u00a0This requires an offset hinge. \u00a0It’s a bit more difficult, but if you’re an observant pilot who likes to try different equipment, it’s worth it. \u00a0These are especially good for planes with high wing loading.<\/p>\n If you’re really enthusiastic, try building some variation of the Fowler flap. \u00a0Fowler flaps are the best choice for planes with high wing loading because they produce more lift and less drag than the other types. \u00a0If you’re good enough to build these, I’ll just shut up because I’m mostly here for basic information.<\/p>\n So, the big question is “Do you need flaps?” \u00a0The answer is yes. \u00a0Build them on at least one plane, and not just flaperon mixing on your transmitter. \u00a0Build a real, separate flap on each wing, and give it a try. \u00a0They’re a lot of fun. \u00a0Then if you don’t like them, you can accurately say that you don’t need them. \u00a0But before you knew you don’t need them, you did need them so you could find out.<\/p>\n","protected":false},"excerpt":{"rendered":" Flaps are a misunderstood feature. \u00a0Sometimes even the people who are using flaps don’t understand them. \u00a0I’m no expert, but I will address flaps as a model airplane builder and casual user of flaps. \u00a0Maybe I can help you decide … Continue reading ![\"flap](\"http:\/\/www.balsaworkbench.com\/wp-content\/uploads\/2017\/06\/flap-types.jpg\")
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