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Building Tips and technical articles. => Building techniques => Topic started by: Dwayne Donnelly on February 08, 2024, 12:20:48 PM
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Brodak plans show 45 degrees of flap deflection, seems like an awful lot. ???
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Brodak plans show 45 degrees of flap deflection, seems like an awful lot. ???
GO HERE THERES A LOT OF INFO ABOUT FLAPS ON THE NOBLER https://stunthanger.com/smf/open-forum/flap-area-differential/
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Brodak plans show 45 degrees of flap deflection, seems like an awful lot. ???
Short answer is no.
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It kind of depends how fast your controls are and how the handle is set op.they can move that much but doesn't ne essarily mean you will actually move them that far. Bell crank line spacing, handle line spacing, horn lengths all play a part in that.
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I have had perhaps a half dozen Noblers over the years and they all had one thing in common stock. They have too much flap. They want to turn around the aft fuselage. Having less flap movement to elevator makes them fly the way I like them. 45 degrees is way too much control, except when it is not. Some people make the full range of control through the handle to about 20 degrees. It is plenty to fly a respectable pattern, even with a plane that really doesn't want to turn, like a Nobler but when you need it to save the plane after an unforeseen engine failure at the wrong spot, it isn't there. The ratio of flap to elevator is far more important than the range. "The Wall" will take care of that for you. My advice on the Nobler is to set it up so that you have 30 degrees of flap and 45 degrees of elevator and hope that you never need it. As a side, it will rotate in a corner more towards the front with this ratio and corner with less pressure.
Just me, others will have their favorite setup for this classic - Ken
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I USED 1' UP ON THE FLAP HORN FOR ELE AND 3/4" ON THE ELE HORN AND ENDED UP WITH 40 DEGREES ON THE ELE AND 30 DEGREES ON THE FLAPS TRAVEL,I ALSO NARROWED THE FLAPS 1/8 " ON THE FLAPS
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Thanks for the replies, I'll set it up the way Ken suggested.
So now another question, what was the thinking back then that 45 degrees was needed?
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Thanks for the replies, I'll set it up the way Ken suggested.
So now another question, what was the thinking back then that 45 degrees was needed?
Let me offer my humble opinion then I will shut up and let the real experts chime in. My first reaction was the type of hinges we used back then. Cloth hinges give you 90 degrees movement with virtually no resistance until you hook up the controls. I think a lot of planes had lots of movement simply because it was there. Next, we didn't have the sophisticated video equipment we have today to see what the plane was doing. I think we (I go back to 1958) just assumed we were using all that control. It wasn't till Bill NetzeBand showed us that there was a limit to how much control we could use that things started to get studied. Flaps made big round turns better but they hurt corners past a point. There are other reasons like the size of the planes and the power we had.
The first flaps were rather small compared to the barn doors on the Nobler. The Chief, which is the Nobler's grandaddy had very small flaps. I suppose we are somewhere in-between today.
Ken
By the way, Doug's setup and trim is what I would do should I build another one.
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Let me offer my humble opinion then I will shut up and let the real experts chime in. My first reaction was the type of hinges we used back then. Cloth hinges give you 90 degrees movement with virtually no resistance until you hook up the controls. I think a lot of planes had lots of movement simply because it was there. Next, we didn't have the sophisticated video equipment we have today to see what the plane was doing. I think we (I go back to 1958) just assumed we were using all that control. It wasn't till Bill NetzeBand showed us that there was a limit to how much control we could use that things started to get studied. Flaps made big round turns better but they hurt corners past a point. There are other reasons like the size of the planes and the power we had.
The first flaps were rather small compared to the barn doors on the Nobler. The Chief, which is the Nobler's grandaddy had very small flaps. I suppose we are somewhere in-between today.
Ken
By the way, Doug's setup and trim is what I would do should I build another one.
The reason that the Nobler had such large flaps is that with a Fox or equivalent, and the relatively thin wing, Aldrich figured he needed it. I would note that on the "Stunting Can Be Smooth" plans, they are hooked up 2:3, not 1:1 like was shown on the Green Box. Do that, and it is pretty reasonable. The Ares is about a I-beam version of a Nobler, and Ted's very light Ares ended up with something like 1:2, at 1:1 it was completely hopeless.
Two other things with the benefit of almost 75 years of hindsight. Aldrich built a bunch of "modified Chiefs", AKA Nobler prototypes. Depending when you asked, it was as many as 13-14 of them. The last problem he solved was, and this is a near-quote - sometimes they would "snap roll". He tried a bunch of variations to fix this, and the final "fix" was to increase the tail moment by an inch.
Interpretiing this, the Nobler wing is pretty thin, and as drawn/designed, pretty pointy. He was already flying wildly crabbed to the side, nose-out yaw, to try to fly it slower and have enough line tension with a *very feeble* engine. This, and a tapered wing, with a too-short tail moment leads to his "snap roll", he was driving the wing beyond the critical AoA just like a Ringmaster, it stalls, and in that configuration, the outboard wing goes first and it does indeed look just like a snap roll. He eventually decided to extend the tail moment, which slowed it down enough to keep it below the critical angle. But, on his way to solving it, he probably tried lots of other things - like making the flaps bigger. Once he fixed it, with the tail moment extension, he stopped, mission accomplished.
What he never appeared to do was go back and try to reverse his previous changes, like the flaps, or diagnose the underlying issue, which was probably the point on the airfoil, and leave the tail moment alone. So you wound up with what you got. Then, he had to try to remember how he built it for the Top Flite plans, and he didn't quite remember correctly, he or someone else putting the controls to 1:1 and extending the tail moment even more (which was probably an improvement). By that time, he was a legend, and convinced he had solved the issue, revolutionized the event, and being the ultimate stunt hero, didn't see any reason to go back and try to re-optimize anything. It was already right, which change it?
Brett
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THE ORIGINAL NOBLER HAS A THINNER WING AND WIDER FLAPS THAN THE GREEN BOX VERSION.IF I BUILT ANOTHER NOBLER I WOULD MAKE THE STAB AND ELEVATOR LARGER...