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Speed,Combat,Scale,Racing => Carrier => Topic started by: Randy Snow on May 26, 2016, 12:40:51 PM
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This appeared in AeroModeler in '65... it was the only design that my Dad ever used and it's the only one that I've ever used. The one pictured here is 2 1/4" ((from leadout hole to leadout hole)) elevator control bellcrank. It's for a .15 carrier Aichi B7A1 Ryusei ( Grace) that I'm putting together. I've made 3" ((from leadout hole to leadout down to 2")). The 1/2" from throttle pivot to elevator control bellcrack pivot remains constant. It's made from 3/32" T-6 aluminum with 6:32 machine screws.
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You didn't mention the dimensions of the throttle cable to pivot -- this should be exactly twice the distance from the main pivot to the elevator BC pivot, or you won't have equal pull on all the lines.
I'm not smart enough to know if this will result in the thing wanting to pull the throttle open or closed, but it'll be one or the other.
I'd just drill a throttle line hole at 1" out from the main pivot -- that should be sufficient.
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I'm not smart enough to know if this will result in the thing wanting to pull the throttle open or closed, but it'll be one or the other.
On reflection, the pull on that one line will be weaker -- instead of the pull being apportioned 1/3 1/3 1/3 it'll go 3/8 3/8 1/4. So it'll act like you're always pulling on that line, and the force will vary with line tension (tra la).
Don't the rules on the line sizes say the pull needs to be equal?
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The tension on the three lines is equal..Is Equal.. the distance from pivot to leadout point on the elevator control bellcrank is the same as the distance from pivot to leadout on the throttle bellcrank. There has never been a problem with this set up, Never. All lines have the same tension during use, Same tension during use. It has never wanted to pull the throttle open nor closed. You have total complete control. No riding on one line. I have never heard of one set up like this ever failing.
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Randy, I have built sold nearly 200 Carrier kits of several sizes over the years using my own BC's. They always worked as you mentioned. Tim, time to relax. Sometimes over engineering isn't worth the trouble. With that said, I would NEVER, NEVER use this type of BC in a Class 1 or 2 ship! Now, with the advent of popularity growing in the use of 2.4, and the fact that Class 1 or 2 activity is really rather slim, the BC shown by Randy is not necessary either. IMHO ONLY.
Joe