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General control line discussion => Open Forum => Topic started by: David Hoover on October 14, 2015, 04:56:27 PM

Title: A Quandary
Post by: David Hoover on October 14, 2015, 04:56:27 PM
I'm in a bit of a quandary.  I'm building a Brodak Strega (the kit) and I'm at a point where I need to make some decisions on the control system.  The kit comes with two nicely made control horns, 1/8" dia. wire with 1/16" thk. x 1/4" wide uprights.  The uprights are drilled with clearance holes for the 5/64" dia. push rod ends that came in the kit.  I don't plan on using the push rods from the kit; I'll make the pushrods from 3/16"OD CF tubing with the threaded ends epoxied in.  I'm just not sure what to do about the control horns.  As I see it, I have the following options:

I can drill them out for 4-40 bolts and use ball joints but I'm a little leery of the offset load the ball joints will put on the uprights.  The Strega is a large plane and from what I've heard, tends to build heavy and I tend to build heavy although I'm trying very hard to lighten up on this one. 

I can drill them out and bush them for the 5/64" dia. push rod ends in the kit, modified to work with the CF push rods.  I'm just worried that by the time I drill a hole big enough for the bushing there will be almost no material left in the uprights for strength.

I can scrap the kit horns and get Tom Morris double arm horns intended for ball joints.  I know that this is hands down the most rugged approach but is it really necessary?

If UltraHobby still made those nifty clevises I could easily use them on the elevator pushrod and maybe even figure out how to make one work on the flap pushrod with it's two-plane articulation but they don't so that's not a solution.

What to do?  Suggestions?  Anyone?  Anyone?
Title: Re: A Quandary
Post by: Motorman on October 14, 2015, 05:35:03 PM
A large project on a serious plane deserves the best. Call Tom Morris.


MM
Title: Re: A Quandary
Post by: Randy Cuberly on October 14, 2015, 09:25:50 PM
I prefer Tom Morris double horns with ball links on the flaps and a Tom morris single adjustable horm on the elevator with one of the aluminum clevises from Ultra hobby products.

Very good stuff!

Randy Cuberly
Title: Re: A Quandary
Post by: Perry Rose on October 15, 2015, 12:15:41 PM
I built the kit with a double star .60re lite and it weighs in the low 60 ounce range. If it had less ribs it would be in the 50's easy.