David Ovenden Posted June 17, 2008 Share Posted June 17, 2008 I'm planning a Fairey Flycatcher model (scaling up a 44" free plan featured in RC Scale International). The full size had ailerons on both top and bottom wings. All 4 could be drooped to act as flaps (presumably as a STOL feature for landing on aircraft carrier decks). By using 4 servos, one for each aileron, I can mix in flap to aileron at the TX and get working flaperons. Does anyone have experience of such a system? I'm interested too in how the full size hinging system worked - anyone know? Were they "freise" type or something different?I picked up the very useful Profile item from Ebay. I also have located an interesting book and a couple of mags with good colour detail and 3-views. However, the flaps are still unclear to me. It would appear that all four ailerons are quite wide and full span. they must have all worked in unison as the cable system linked the top and bottom ailerons together. There does not appear to be a separate inboard flap, so if all 4 ailerons lowered as full-span flaps that would have have quite an effect! The FAA replica would be worth a look, though it does seem to have "disappeared". Anyone got any photos of the wing/ail/flaps on this plane?I've now got the enlarged plans, the 5" Williams wheels, servos and engine lined up. So I need to made some sort of decision regarding the wing/aileron design before cutting balsa I guess!Any info appreciated Quote Link to comment Share on other sites More sharing options...
Jim Newman Posted June 18, 2008 Share Posted June 18, 2008 My advice would be, when you lower those "flaperons", is BE CAREFUL. When the full span ailerons are lowered you have effectively increased the Angle of Attack of all four wings....thus putting you closer to the stall. On the full size aircraft, the advantage was that the the AoA has been increased to slow the aircraft without raising the nose. Raising the nose obscures the carrier (and batsman) from the sight of the pilot who already is sitting behind a visual obstruction in the form of a large radial engine. He has the advantage of an airspeed indicator to let him know how things are going. YOU don't!In more modern times, several aircraft were built on which the wing leading edge could be raised to achieve the same effect. The Supermarine Dumbo was one, the Supermarine Seagull was another, while Vought had a swept wing carrier jet...the F-7...that raised its wing l.e. so that the AoA could be increased for t.o. and landing, while still allowing the pilot to still see ahead instead of having to peer around a large aircraft nose. Jim Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted June 18, 2008 Author Share Posted June 18, 2008 Thanks JIm,Once built I will be pretty warry of the flaps until I see what effect they have. I reckon the ailerons will become pretty ineffectve too once the flaps are down - with risks of drag-induced reverse yaw effect. May try mixing in the flap on the lower wing ailerons only to start with.Still would like to know what sort of hinging system the original used!David Quote Link to comment Share on other sites More sharing options...
Jim Newman Posted June 19, 2008 Share Posted June 19, 2008 Hello, again, David..... You will not experience adverse yaw if you have built in a suitable amount of aileron differential movement. That differential will still be present, even though the ailerons are lowered. Don't be shy with it. My 8 ft Telemaster is rigged with a 2:1 differential and turns in a co-ordinated manner. But then, as f/size airplane driver I habitually use rudder and ailerons. together. Quite a few f/size aircraft used drooping ailerons as the flaps were lowered. They were linked on a common bellcrank. The Miles Messenger was one type of aircraft. I might be able to determine what type of hinges were used on the f/size Flyswatter. Give me a few hours. I'm up to my neck in airport legalities, at the mo. By the way...I hate this term "fuzz" for fuselage and "stab" for stabilizer or tailplane, don't you? SO childish. I thought that we British were better educated. Jim Quote Link to comment Share on other sites More sharing options...
Jim Newman Posted June 20, 2008 Share Posted June 20, 2008 Greetings once again, David. I found quite a lot of material on the Flycatcher, including a cut-away illustration. It is pretty obvious that the aileron hinging was nothing fancy, being hinged to the back of the rear spar with what appeared to be plain old (horizontal) pintle hinges, as you might have on your garden gate! The hinges would be on the airfoil datum line with quite a large space twixt aileron and rear spar. A "wings vertical" shot reveals no daylight between the wing and aileron, so it is obvious that there is a gap seal of loose, doped fabric, glued to both the wing and the aileron. On models, an adhesive plastic tape, carefully laid into the gap, will suffice. If you have any real Tiger Moths (my old mount) near you, check the ailerons on that, to see what I mean.A shot of a 'catcher with the flaps lowered shows no more than 15 degrees down, from what I could roughly measure. I hope you are using four programmable aileron servos, because the control circuit is all done by cables, hence the linking cable between upper and lower ailerons. This means that it is a closed loop circuit of tight cables around several pulleys. If you are using only TWO servos (say one in each lower wing) then those vertical link cables must be of rigid piano wire.Let me know if you need more and I'll try to clarify.Jim Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted June 20, 2008 Author Share Posted June 20, 2008 Jim,Many thanks for the very useful information. I think I have enough now to plan the hinging system. I will be using 4 servos (each with its own channel) and program the mixing (differential and flap mix) via the Tx. I do also have a JR Matchbox unit as well that allows independent, end-point and throw adjustments of up to 4 servos from 1 channnel, so that might be useful possibility too. However, I won't go in for a "real" cable link between top and bottom ailerons, so as to allow experimentation with independent flap mixing on top and bottom ailerons. ie Flap mix only to bottom aileron or to both. Will use the traditional shiring elastic to give the impression of the cable.The information I have suggestes that in tests around 8 degree flap was used for take off and I guess 15 degree on landing makes sense.(although this is not specified in the article I have) However, they certainly seem to have been pretty effective!"Take off to unstick distance was 363 ft with no flaps, and 190 ft with 8 degrees of flap. Minimum speed with flaps down was only 47 mph. Initial deck landing trials were conducted on HMS Argus in February 1923 and the behaviour of the aircraft was deemed to be exemplary".We will have to wait and see whether the models reacts in the same way.RegardsDavid Quote Link to comment Share on other sites More sharing options...
Jim Newman Posted June 20, 2008 Share Posted June 20, 2008 A wonderful example of how a small amount of lowered flap increases the Coefficient of Lift of an airfoil, David. A Cessna 172 , with 20 degrees of flap and a cool day, literally floats off a grass runway runway in about 450 feet, instead of the usual 650 feet.Ah! Nostalgia. ....HMS Flatiron! An uncle was on the Furious that, sadly, never really was acknowleged for all the hard work she did in the N. Atlantic. She also got minimal mention for her "first" in fly off and recovery of a Sopwith Pup under Lt. Cmdr. Dunning.Happy landings from the left side of the Atlantic....Per ardua and all that!Jim Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.