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Building Tips and technical articles. => Building techniques => Topic started by: Bill Gruby on November 08, 2007, 01:36:16 PM
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Gentleman;
During a search for something else and today in an email from a good friend, this model popped up. Please note the "Bell Crank" position. Did this set up work and if so why has it been lost in time.
"Billy G"
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Bill
That is probly where the name came from.
Willis LL~ S?P
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Hi all.
Tom Dixon has plans for the Gyrator in his catalogue, but I think he changed BC position to an "usable" one.
Hope it helps.
Regards.
Manuel
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Bellcrank position is irelevant, but I have heard of these being built with a more conventional leadout position, allowed I believe by vintage rules. I did build a model with this l/o position once and it had some very strange characteristics, cured when I rejigged it to conventional position.
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Wow, that's a thin airfoil!
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Never mind the bellcrank...with that leadout guide location, the thing must have flown sideways.
"Improved handling"?
--Ray
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A really nice find "G"Man!....great plans and yes...that is a skinnnyminne airfoil...must have been a rather peppeee' flyer?
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Same guy (Williamson?) had an extremely similar design called Ringmaster published in a different mag at almost the same time. My guess is he kind of sold the same design twice and had to make a few changes to say it was different.
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Where did you see the name Williamson on the "Gyrator? You said "Same guy (Williamson?) I didn't see it or missed it.
This is the Williamson Ringmaster.
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Billy, HI!
NB: Ian, I think both the Ringmaster and the Gyrator were in Model Airplane News...
Billy: I built Williamson's Ringmaster about 20 years ago. The main differences were that the Gyrator has flaps and that odd bellcrank/leadout layout. Both, I believe, are OTS eligible, so the Ringmaster is the better choice, for the no-flaps bonus, edit to add: for the more reasonable leadout position, at least. (edited because I'd mistakenly recalled the Gyr as having flaps...)
Harry W also did an article a short time later, probably also in Model Airplane News, about vertical CG. He should know. Both the Ringmaster and the Gyrator build with the vertical CG WAY too high. Both planes fly banked right because they are topheavy. My Ringmaster eventually died because of the difference in tank height from inside/upright to outside/inverted. I had used a moderate power .19 instead of the indicated howling .29 - perhaps, with the added power, the bank would not have proven fatal. It went too fat, inverted, to get back upright - I let it fade into the ground, mostly because I was tired of fighting that built-in flaw... If I'd inverted the engine, it might have improved things, but it wouldn't have been Harry's Ringmaster...
An inverted engine would also have made the tank installation less fussy - there is D*** little room above the mounts to hold fuel for an upright engine in both of these. The fuel tank bay, if the engine were inverted, would be better.
Yeah, the airfoil is thin by our current standards, but Lift calculates from the square of velocity. With a honking .29 of that era, or a decent LA25 today, either one could fly fast enough to have plenty of potential. BUT, that vertical CG thing will still be there...
As much comment has put forward, bellcrank location is essentially irrelevant. What IS relevant is the leadout location! On the Gyrator, that is much too far aft. Back in those days, we didn't trust centrifugal force to keep the lines tight enough to assure control. Look at other plans from the era: huge rudder offsets, generous engine offset, aft leadouts.... Today, we know better. And, we know more about vertical CG...
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Where did you see the name Williamson on the "Gyrator? You said "Same guy (Williamson?) I didn't see it or missed it.
This is the Williamson Ringmaster.
Bill, I didn't see it, I recalled seeing both in the PAMPA Old Time Anthology, and noting they were by same designer.
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Just build it really light. Thin wings do not carry weight well. Something like the Gyrator probably should weigh in at 26 oz. or so with a six coat, dyed dope finish. Any more and it will fall out of maneuvers like a Sterling Ringmaster.