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Design => Stunt design => Topic started by: Allan Perret on June 09, 2015, 10:38:57 AM
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Sullivan's "Aluminum Ball Connector with Locking Sleeve" in our control systems ? Specifically for driving split flaps..
Link>> http://www.sullivanproducts.com/ProductIndexMainFrame.htm
Then click on Super Horn
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I use them on the retract servo in my BVM Electra jet, where they have to take a big load in both directions- they work flawlessly in hundreds of flights. They would be perfect for a take apart application.
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I use them on the retract servo in my BVM Electra jet, where they have to take a big load in both directions- they work flawlessly in hundreds of flights. They would be perfect for a take apart application.
Do you think the load in your retract application is comparable to what we see on full size stunter flap horns ? This would be split flaps, 2 separate horn connections each driving one flap, left and right.. Did you use the 4-40 or the 3mm ?
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If Bill hadn't said what he said I would have said "Hell No!" Even with his testimony, I think I'd weigh the relative danger of landing gear not coming down vs. flaps failing at some arbitrary part of the pattern (i.e., straight down and 15 feet off the deck), and then I'd use a conventional ball link.
Take-apart models that have the wings plug into the fuselage leave the flap horn pivoted firmly on the fuse -- I'm not sure what folks usually do, but I expect that they either have a deep notch in the end of the flap (like a lucky box left open on the fuselage side) or they have removable flaps that slide off of the flap horns. Are you taking your plane apart somewhere else?
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Not a take apart. I am just wanting to drive the flaps from dual pushrods to facilitate wing leveling without having to tweak a horn. I know that can be done with standard ball links, was just curious about others opinions on the suitability of this Sullivan product for stunt birds. I have some on order, will try them first on a lesser profile before putting them in a serious machine. If its a rugged and reliable product for the loads why not. With an access hatch just above the flap horn area, it would be convenient to make flap adjustments.
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If you get Stunt News, look for an upcoming article by Paul Walker on this. He doesn't do a hatch -- instead, there's just one little hole for a long hex key.
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be carefull about the geometry when driving flaps with two pushrods, its very easy to get assymetrical throw,,
actually its very hard NOT to get assymetrical throw
well without an intermediate transfer arm, or some such
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I'm putting my horns as close together as I can get them for just that reason. I considered an idler, but I'm too idle.
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Do you think the load in your retract application is comparable to what we see on full size stunter flap horns ? This would be split flaps, 2 separate horn connections each driving one flap, left and right.. Did you use the 4-40 or the 3mm ?
The design of the retracts in this model is terrible, yet I have never had a pushrod come loose or ball joint fail in many NOT perfect landings. I'm using the 4-40's. Yes, I think that including the side loads that the retracts are suffering more of a load than in a stunter's flaps.
https://www.youtube.com/watch?v=Bk2K4hkAd5w
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My first look at the Sullivan catalog line, although I find some of their products in our LHS. We sometimes bad-mouth the R/C portion of our hobby without realizing how many R/C products we use for C/L.
Floyd
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Talk to Paul Walker. He uses a split flap setup that has a unique arrangement to do just what you want without the asymmetry.
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I'd trust it in the throttle arm application it was designed for. An aluminum ball in place of brass or steel would probably be OK in a conventional ball connector with the ball bolted in place on the horn.
The problem is not absolute strength but fatigue resistance, and as Tim W. reference to the consequences of in flight failure.
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I'd trust it in the throttle arm application it was designed for. An aluminum ball in place of brass or steel would probably be OK in a conventional ball connector with the ball bolted in place on the horn.
The problem is not absolute strength but fatigue resistance, and as Tim W. reference to the consequences of in flight failure.
I can't find one place on their page where it mentions "throttle arm application" ? I have used these for years, they will work great in a control line application.
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...Odd, click the link and either click "control system hardware" or "ball joints" ( both take you there ). The first line of the description reads " Heavy duty aluminum ball connector for throttle connections and internal servo arms." Cheers, John
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I must not have dug deep enough then... but that does say internal servo connections also. So they aren't "designed" for control line applications. Big whoop. They will work great, they will withstand WAY more than our CL planes dish out. I have had the piano wire fail on the Electra retracts, and the ball link was still in place.