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Question about rudder offset  Empty Question about rudder offset

Post  akjgardner Sun Jul 23, 2023 6:44 pm

I got a ringmaster at a swap meet. I repaired everything but the rudder and vertical finn. My question is instead of a Finn and rudder. Could I just use a vertical Finn and offset it ?
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Post  GallopingGhostler Sun Jul 23, 2023 6:52 pm

I just looked at my Sterling 42" Kit S-1 and my 30" Kit S-5 Junior. The Jr. is set up as you describe, but it's fuselage is about the same thickness as the larger S-1. (I think S-1 is 1/2" thick, S-5 is 3/8" thick.)

You'd lose about half of the rudder offset if you made the rudder one piece, because otherwise, the rudder would leave the fuselage edge half way. You might be able to strike a compromise though with less split, though.
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Question about rudder offset  Empty Re: Question about rudder offset

Post  Ken Cook Sun Jul 23, 2023 7:09 pm

Rudder offset is one of the worst practices to use on a control line plane. A Ringmaster will fly better with no rudder at all vs one with a offset rudder. A rudder isn't needed and when you offer rudder offset, you offer yaw to the plane. Why is this a no no? It's because your killing speed. Speed is the success of any control line plane. Engine offset, rudder offset are practices used from 50+ years back.
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Post  akjgardner Mon Jul 24, 2023 8:36 am

Thanks George & Ken . So I am assuming the wing weight is enough to keep line tension? Thanks again
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Post  Ken Cook Mon Jul 24, 2023 3:15 pm

Essentially, tip weight is needed on take off more than anywhere. You use only enough tip weight. A S-1 Ringmaster should need no more than 5/8 oz. and that by my standards is too much. I fly most of these planes using 100 lb Spectra which is lighter than steel requiring even less. So once again, speed is what offers line tension. Tip weight will insure the wing is low on take off until the plane is up to speed. After that, the tip weight is along for the ride. When you buy a swap meet plane, it's critical to sight the wing. Look from behind and sight trailing edges and airfoil fore and aft. Critical to check the wing to see if it's twisted. Sight the plane from the side looking down the trailing edge from the wingtip and insure the trailing edge isn't up or down. If in doubt on first flight, tape two quarters on the tip or use some modeling clay. Fly it and then remove it if it's not required.
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Post  GallopingGhostler Mon Jul 24, 2023 4:12 pm

I received as a gift along with Testor McCoy .35 Red Head engine (good and parts engines), a partially built S-1, from a kind gentleman from Northwest US, getting out of the hobby because of age a decade ago. We linked up through I believe BOTR.

He mentioned about the wing being warped. I found that when assembled, the leading edge in two parts (part of kit engineering to fit stuff in the box) was misaligned from the start, creating a small amount of dihedral, causing the warp. Attempts at straightening did nothing. I uncovered it, carefully partially disassembled the center joint, I reassembled it correctly and reinforced it, which took out the warp.

It has a good amount of pull once in motion.

Joe Wagner was one of the early pioneers to dispense with rudder offset. This was at a time when C/L was still in its relative infancy in the late 1940's/early 1950's. To help bank the plane slightly so it would maintain line tension in stunts, he added a rib bay to the circle's inside wing, adding slight asymmetry to the wing. It would through a touch greater lift and increased attack angle bank the plane outward.

As we see, through refinements in time, this assymmetry is no longer used.

It is just a personal opinion, but I believe the thought behind rudder offset had to do more with the low time flyer. They wanted to make him succeed. When the plane looses velocity, rudder offset helps to re-establish line tension. With half-A as light as they are, it is as you mention, Ken, way overpowered for 18 inch wingspan, under 100 cubic inch wing area with a Cox .049 engine.

What I observed flying those in sheet balsa is that as soon as the engine quit, they just sort of fell out of the sky, glide was almost nonexisting. I was lucky if I even achieved a quarter circle to land them. They were still fun, even though stunts were crude and nearly non-existing.

If one is flying contest antique stunt, must they maintain the physical appearance of the adjustments in order to qualify?

Regarding tip weight, I recall a discussion some time back. A seasoned flyer did his "Ted Talk" write up in I think a magazine article. I think he had an F8F Bearcat warbird, a good size one. Adjustments to rudder, thrust line, etc. left him with less than desireable adjustment through the R/C flight envelope, affecting maneuvers. He then found, adding a touch of right wingtip weight to compensate for take-off engine torque roll solved his take-off problem totally without affecting the rest of the flight. Take-off and transition to flight was smooth.
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Post  akjgardner Mon Jul 24, 2023 6:00 pm

Thanks for the comments guys , they help a lot . I inspected the airplane pretty good . The only problem I saw was the horizontal stabilizer was of about 3/16 off from one side to the other. Also the bell crank isn’t as smooth as I would like it to be. As I’ve mentioned before, Im more of a RC Guy but have flown 1/2 control line . Now I have 2 larger CL Planes . This ringmaster and the shoestring I built in my Uncle Jerry’s honor. These are both going to be my trainers for the bigger stuff. Thanks again for the help.
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Post  Ken Cook Mon Jul 24, 2023 8:16 pm

George, this weekend is the Philly Flier Stunt contest. Old time Stunt will be flown on Saturday. I don't fly OTS myself. I'm aware of some of the rules in regards to the plane itself. The rules are that the model must faithfully represent the outline and airfoil of the originally printed model prior to Dec 1952. One can make changes such as wider fuse to accommodate 2" tanks, change landing gear as long as it exits in the same place. There's nothing I'm aware of where the rules state one must utilize rudder offset.

As for the Ringmaster, Sterling instructions were extremely poor and not very explanatory. Bellcranks were not provided with Sterling kits so it was up to the builder. If the builder used a 2" bellcrank, the plane was doomed. If they used the outermost hole in the bellcrank this killed the plane's performance. Most would think that the more elevator movement equated to quicker turning performance. This in turn did the complete opposite and made the plane fly extremely bad. The Ringmaster requires only about 25 degrees of movement. Too much elevator acts like a air brake. Remember, speed equates to smoothness and speed is how you obtain line tension. The wing is already too thin on a Ringmaster and the faster it flies, the better it flies. All that a fast moving elevator with too much control is make it flop out of the sky.
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Post  706jim Mon Jul 24, 2023 10:29 pm

I built one of these after destroying my Circus Prince. And the wing on this model was too small and too thin. It would do wingovers and that was about it.
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