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Model Forum / Radio Controlled / Air Models / June 2004flapperons
Hi all, I am having a go at setting up flapperons on my Tail dragger. I am doing it using chanels 1 & 6 and wing- mixing them in my futaba set. It has been suggested that I program-mix some down elevator (channel 6 the master and channel 2 the slave) to help keep the nose level, can anyone suggest a percentage of mix for this. Also any views on the pros and cons of using flapperons would be appreciated. Thanks. Andy. There's absolutely NO way to guess the elevator to aileron mix that will work best when using flaperons. Each aircraft is different so the only thing you can do is to dial in about 5% as a "guess" start point and try it. You should be able to get it right after 3 or 4 test flights. Flaperons are fun and are a good alternative to flaps if the aircraft is already built and you want to play a little. The only thing to watch out for is that the aircraft will tipstall easier with flaperons than it will with flaps so do some stall tests at altitude until you learn to judge a safe slow speed with the flaperons down. You don't say what kind of aircraft you have, but if it's a floater like a Cub or something of that sort, you might have more fun with spoilerons. It's the same set up except that you're dialing UP aileron on both sides (and also some up elevator to compensate). With a floater, you're problem is not usually slowing down for landing (needing flaps), but that the aircraft doesn't want to land and floats down the entire runway while it "thinks" of landing. Spoilerons are fun as hell because you can pop the switch on final and come in for an almost "carrier" landing. MJC > Hi all, > I am having a go at setting up flapperons on my Tail dragger. I am doing it [quoted text clipped - 5 lines] > Thanks. > Andy. Thanks for your reply MJC My model is Blackhorse models Super Air Low wing sport/aerobatic... Andy. > There's absolutely NO way to guess the elevator to aileron mix that will > work best when using flaperons. Each aircraft is different so the only thing [quoted text clipped - 26 lines] > > Thanks. > > Andy. > Flaperons are fun and are a good alternative to flaps if the aircraft is > already built and you want to play a little. The only thing to watch out for > is that the aircraft will tipstall easier with flaperons Not tipstall. Wing-drop stall. > You don't say what kind of aircraft you have, but if it's a floater like > a Cub or something of that sort, you might have more fun with spoilerons. [quoted text clipped - 3 lines] > doesn't want to land and floats down the entire runway while it "thinks" of > landing. Airplanes that "float" are typically being approached with too much speed. Almost any airplane will do this if the approach speed is too high. Rule of thumb is to approach at 1.3 times stall speed (which can be difficult to determine without airspeed information) and to bleed speed off further by reducing power and raising the nose a bit before getting into ground effect. I used to fly a Taylorcraft, which is famous for its float. I found that I had to approach no faster than 1.3 times stall, and then get even that down before getting near the ground. I see other modelers approaching way too fast, or too high and then diving at the runway, which produces the same problem. You have to PLAN your approach way back on downwing leg, get the right speed at the right altitude at the right point. Then the airplane is easy to land. Spoilers shouldn't be necessary except for very slick, very fast, low-drag airplanes like airliners or a very few smaller singles. Those are the only full-scale airplanes you'll ever see them on. Dan Umm... the wing usually tags along with the wing tip. Too much sugar in your coffee?? As far as the spoilerons on a floater that won't land: You never flew a giant Telemaster, have you? MJC > > Flaperons are fun and are a good alternative to flaps if the aircraft is > > already built and you want to play a little. The only thing to watch out for [quoted text clipped - 28 lines] > > Dan > Umm... the wing usually tags along with the wing tip. Too much sugar in your > coffee?? "Tipstall" is a misnomer that implies that the wing will drop only if the wingtip stalls. Most wings have stall behaviour that is progressive, beginning at or near the root at the trailing edge and progressing forward and outward as the angle of attack increases. It's NOT a sudden thing, and the wing can drop if the stall is slightly more advanced on that side. THE TIP CAN STILL BE FLYING AND STILL DROPPING. I've said it before: get some textbooks. See http://www.av8n.com/how/#contents I quote from Chapter 18 of that excellent site: "Stalling Part vs. All of the Wing "We can arbitrarily divide the wing into sections; each section contributes something to the lift of the whole wing. It is highly desirable (as discussed in section 5.4.3) to have the coefficient of lift for sections near the wing-root reach its maximum early, and start decreasing, while the coefficient of lift for sections near the tips continues increasing1 (as a function of angle of attack). "Therefore it makes perfect sense to say that the sections near the roots are stalled while the sections near the tips are not stalled. If only a small region near the root is stalled, the wing as a whole will still have an increasing coefficient of lift --- and will therefore not be stalled. "We see that the wing will continue to produce lots of lift well beyond the point where part of it is stalling. This is the extreme slow-flight regime --- you can fly around all day with half of each wing stalled (although it takes a bit of skill and might overheat the engine)." This website has an enormous amount of easy-to-understand info and is well worth the model flyer's time. > As far as the spoilerons on a floater that won't land: You never flew a > giant Telemaster, have you? I'll bet it's being approached much faster than necessary. You've never flown full scale, have you? The aerodynamics are the same for all subsonic airplanes. See the website section on landings. I don't put sugar in my coffee. Real pilots drink it black. Dan > > "MJC" <nospam@noway.com> wrote in message > news:<ca1r5m$ksl@library1.airnews.net>... [quoted text clipped - 37 lines] > > > > Dan Oh c'mon, get real. Using the term "tip stall" is totally correct because it very accurately describes what's happening with the AIRPLANE, which is what we are talking about. I'm not trying to impress anyone with my aeronautical knowledge, I am simply explaining "real world" behavior in a way that's relevant to the conversation. The whole point of washout is to insure that a stall occurs in exactly the way you describe, i.e., that the tip stalls LAST so that a stall, when it happens, is progressive, gentle, and recognizeable. That's why the inner area of a wing will stop producing lift before the outer wing area does and the airplane is still able to be controlled. It doesn't matter one bit that the inside of the wing "stalls" while the tip hasn't, because we're not talking about the aerodynamics of airfoils here, we're talking about an AIRPLANE stalling, period. If the tips are still flying, so is the airplane, slow flight or not. An AIRPLANE has NOT stalled, even if part of the airfoil has, as long as you can control the airplane. Once either tip stalls, the AIRPLANE has stalled and is no longer controllable. I guess the anal retentive need to ply their trade here in rec.models, too. MJC > > Umm... the wing usually tags along with the wing tip. Too much sugar in your > > coffee?? [quoted text clipped - 85 lines] > > > > > > Dan > Oh c'mon, get real. > Using the term "tip stall" is totally correct because it very accurately [quoted text clipped - 18 lines] > > MJC If the airplane is not in coordinated flight near the stall, the stall will be further progressed on one wing and that wing will drop simply because the wings are not generating equal lift. In a skidding turn, the inside wing will drop first, even if the tip is not stalled, because the outside wing is less stalled than the other. To claim that the wingtip will not drop in such a maneuver until the tip stalls is completely in error. If that was the case, all we'd need for flight is wingtips. And the airplane won't keep on flying as long as the tips aren't stalled; if the enough of the wing is stalled that there's insufficient lift generated, it will sink, and if the stall pattern is large enough the centre of pressure moves way back and forces the nose down, even if the tips are still flying. The airplane has stalled. We can fly a Cessna 172 (and many other airplanes) at the point of stall, get a bit of skid going, see that inside wing drop and still pick it up with aileron, something that would be impossible if the tip was stalled. Application of aileron will aggravate a wing drop if the tip is stalled, and some airplanes are really nasty that way. Washout isn't necessary in many airplanes to control stall progression, though it makes it a lot safer. Rectangular wings normally have no washout because the stall progression is just the way we want it. Tapered and elliptical wings will often have some washout to improve the stall. Not anal retentive. 31 years of full-scale flight. Commercial Pilot, Flight Instructor, Instrument Flight Rating, Aircraft Maintenance Engineer. A college degree in this stuff. A modeler before going to full-scale. And a son who I got started in RC. Dan I'm also a CFI and with all the typical ratings that lead up to that, but what we're trying to do here is to put things in a way that casual R/C flyers can understand and use. I started falling asleep half way through your last post, and I KNOW what you're talking about. How interesting and useful do you think your explanation is to a guy who's happy just to fly a circle in the air and make a landing without damage? If I were to simply drive it into someones head to keep the longitudinal axis of the aircraft either level or slightly nose down, and to keep the wings from banking more than 20 degrees at any time, and maintaining airspeed that will allow him to do those two things, he'll never crash. That's information that a casual low-time flyer can use without having to pull out his copy of "Airfoil Design - by Dan Cohen" and trying to land at the same time. You're not wrong, you're just not relevant to the discussion in a meaningful way that the average R/C guy can use. MJC > > Oh c'mon, get real. > > Using the term "tip stall" is totally correct because it very accurately [quoted text clipped - 47 lines] > > Dan ROFLOL! I don't have as much time or ratings as eithor one of you, but I sure can explain what he needs to know in less time and space! Now don't get the idea that was a shot, because I watch what both of you say, rather consider it constructive. C/I SEL > I'm also a CFI and with all the typical ratings that lead up to that, > but what we're trying to do here is to put things in a way that casual R/C [quoted text clipped - 78 lines] > > > > Dan Yes indeed, I saw the humor in that exchange as well :-) I just didn't have enough sense to walk away from it, but I assure you that my last response was the last in that goofy thread. If Dan (the almighty aviation god) wants the last word to convince us of his total superiority of the subject, he can have it. MJC > ROFLOL! > [quoted text clipped - 95 lines] > > > > > > Dan Hello all: Just i want stay off all the confrontation about the "medals" of each one. now, what i think is the real explanation: -It is desirable that a plane that begin to stall, still have some control -It is desirable that a plane has the maximun efficience from his wing to gain speed and reduce consum A plane flies because the diferent speeds between upside and downside of the wing are diferent and produce a diference of pression, but as the wing is not infinite, at the tips a turbulence between the two sides is generated, making drag in form of spiral turbulence track, in order to reduce the drag, designers reduce the cord at the tip to generate less sustentation, as the diference in speed is lower as the way to walk is less, because the reynolds number is lower and the eficience of the profil is lower, yes they reduce drag but as eficience is lower the wing tips need a higher speed to be operatives. There are some solutions to this problem, maintain the control at wing tips and reduce the drag: As the stall of a given profile is function of angle of attack we can reduce the wing tip AoA giving some washout at wing tips We can add Extra Leading Edge Extesions to modify the profil and gives it less AoA, because profile is longer now, just the inverse from flaperons or spoilerons In function how ailerons are placed on the wing, they can be outer wing, middle or most rare inner, they affect how the wing is designed, the goal is when the wing is stalling, still have some aileron control Now my self experience: The most of times you get a plane that are more fast than you want for landing, this is the main reason to apply some kind of brake and reduce speed, as the most of the planes have not dedicated flaps ( if you see, all the planes have the flaps inside the wing, ) we use the ailerons as flaps, lowering the ailerons increase drag and also AoA as you lower the rear edge of the profile, yes the plane slows but it is more propense to stall( this is because dedicated flaps are inside wing, the first part of the wing stalling is the inside, getting still some control at the tips). In my opinion, just use spoilerons, they slows a bit less than flaperons but also reduce the AoA, and in consecuence yo can increase the AoA of the plane, showing more frontal section and adding drag to reduce speed, I use a 40% of the aileron way upside, seems to be small but you will land in no wind days as if you are in a moderate wind day. As i stated before, it is a mix from what i know and my experience, sure other people can add or refuse that, i am not a master. Salute all, Fermin > Yes indeed, I saw the humor in that exchange as well :-) > I just didn't have enough sense to walk away from it, but I assure you that [quoted text clipped - 111 lines] > > > > > > > > Dan > I am having a go at setting up flapperons on my Tail dragger. I am doing it > using chanels 1 & 6 and wing- mixing them in my futaba set. It has been > suggested that I program-mix some down elevator (channel 6 the master and > channel 2 the slave) to help keep the nose level, can anyone suggest a > percentage of mix for this. Also any views on the pros and cons of using > flapperons would be appreciated. Why not go full house, Use the Air brake switch to have flapperons, spoiler/air brake, then set up flapperons to elevator on another switch the combinations are exhilarating or is that adrenaline running. |
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