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Building Tips and technical articles. => Building techniques => Topic started by: Ty Marcucci on December 04, 2007, 01:58:50 PM
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In many of the older style Classics and a few of the OTS planes I have built in the last six years, most have had the same , for me, problem. How in the world do you get any clearance for the push rod/control horn???
Especially if you use the ball joints most of us use now? I try to stay away from the old "zee" bend, because it is almost impossible to easily do any minor trim adjustments.
What I have done is one of two modifications. First I used a larger or wider tail post at the rear of the fuselage, giving me some room. Or that and cutting holes in the sides to allow for room and then blanking over the holes with thin balsa. Thus the bumps are not that large or noticable.
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HI Ty,
Of course, the connection was a washer soldered onto the end of the pushrod *back in the day*. That needed close to zero clearance, as you know.
Putting *scabs* over the area where the ball link needs clearance is probably the least obtrusive way to do it. They can be smoothly blended into the fuselage side. I also cut a vertical slot to access the adj. elevator horn.
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TY- I have made the covers for the aft hatch out of a soda can. Very thin and I just stick it in place with clear tape. Even left natural aluminum color they look like they belong.
Don
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Hellow All I think Central Hobbies has a clevis made out of aluminum that is both strong and light. They had them in four sizes. The pin is held in place with a screw and also came in diff thred sizes also.
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We usually use a z-bend in the rear of these airplanes and a ball link up front which gives you at least a little adjustment. You are right though many of the older designs are small at the tail where the controls go. As stated in an earlier post there are some nice clevis out there. Central Hobbies has some as well as Ultra Hobbies. A clevis might be a good solution if you need to have it adjustable.
Jim Snelson
Control Line Central
www.clcentral.com
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TY,
This is a major problem with many of the Classics. While I have used a Ultra Hobby clevis in my "Top Hat" that's is a modern airplane with lots of room built in to the design''
The "Carousel" that I build had about 1/4" clearance for controls inside the rudders. With the high tail, it made adjustable items next to impossible. For clearance I cut a curved slot in the rudder sides tha follows the horn travel, to clear the horn and Hayes clevis, and then covered the slot with silkspan. That gave just enough clearance, and after it was painted you couldn't see it.
The "Sea Vixen" also has horrible clearance problems in the aft area of the rudders, where the horn has to travel. I have the controls closed up now, but I will be opening the tops of the booms again to try to get smoother operation, since I am not happy with it. This has been the most challening project I have ever done. but for that reason it is also the most interesting project, because it is such a big challenge.
I am assuming that your "Knight" will also have to have a large braced "Z" in the pushrod to get up to the high "T" tail.
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On the Vulcan, I cut out the fuselage sides amply where the horns pivot. I cut punk 1/8th" covers which I glued in place and sanded in. You have to look to notice them, and nothing comes close to binding. Plus you get about 1/4" more surface to glue the stab to!
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Ty,
Sheeks' Knight? The T-Tail beauty?
Remember the brace wire to limit bending in the elevator pushrod, and use a fairlead or two on the straight section to make sure.
The geometry of the pushrods is a trip, no?
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Well, by sheer accident I am on the right track. If you guys do it, then it must be done more than I realized. But then I am not in the habit of tipping planes over to look at their tails. LL~ I'll have to peek uner the stabs and see if more do it. H^^
I basically started that only when we went to ball links and adj. elev. horns.
Before that I just used the soldered washer. H^^
Bill <><
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I basically started that only when we went to ball links and adj. elev. horns.
Before that I just used the soldered washer. H^^
Bill <><
Oops! I must be dangerously low-tech. I still use soldered washers.......
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still a great way of doing it, but much harder to get the freeness and adjustability! LOL!!