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Building Tips and technical articles. => Building techniques => Topic started by: Chancey Chorney on February 14, 2016, 06:20:53 PM
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Hi all. I am in process of building my first 'Big Bird'. I, until now, have only done flying in the 1/2a category. Back around 2000, I purchased a Sig Banshee and until now kind of forgot about it and received it back again. So, I have repaired a few of my beginner mistakes and am now at installing the leadouts/bellcrank. I was going to do solids, but have changed my mind and am now planning on installing steel coated cable leadouts. The hobby shop is not close, and I have fishing leader material on hand, along with the correct crimp sleeves and tools. Anyways, I did some reading here and have concluded that this should be alright. I am just looking for some conformation as well as if the material I have is adequate. Thank you in advance.
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How thick is the nylon covering, and is the .032" figure with or without?
Uncoated .027" is kinda-sorta the standard, even for bigger ships than yours. I'm pretty sure that what you have will work, if perhaps be overkill.
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The wire leadout material dimension is coated
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Hi Chancey! I also used .027 on my banshee and twister. I'm assuming that what you have would be a little over kill. One sure test would be to strip off a little covering and measure it. But if i had to guess I'd say you're good. You could also order a couple sets of stuff from county line hobbies. And if you have too much trouble, you know i could send it to you.
Sorry, i ramble.... But the strength there should be plenty. I have no idea about crimping with the coating. I'm not a deep sea fisherman.
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I think you'll be fine. I wouldn't crimp my leadouts -- wrap them with wire per the AMA rulebook.
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Ok. Back again. So I got ready to do it, got all my supplies and started only to realize the crimps I had were too small for this wire. I swore I had them though. So, I referred to the plans and followed the diagram and instructions on them. I looped them, wrapped with copper wire, folded back over again and wrapped till the termination point. I then applied a coat of 5 minute epoxy to the wrapped area. I then upon leaving the room saw the correct crimps sitting on the floor! But I am now glad I did not find them earlier and did it properly. In a while when the epoxy had a while to fully set and cure, I was thinking of putting a piece of shrink wrap over them for a bit of added protection.
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Sorry I forgot to ask previously. What would you recommend to use as a leadout guide for this type of leadout wire. I am thinking that brass tubing would cut the wire and or coating, possibly jamming the controls. Thanks again.
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Brass tube works great on bare wire. If anything cuts anything it's the wire cutting the tube.
I'm not so sure with the coated wire -- I'd make a pointed end on a piece of 1/8" or 3/16" music wire and use it to bell-mouth the ends of the tubing, if I were in doubt.
Do make adjustable leadouts, BTW.
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The Banshee wants a Brodak 4" bellcrank with the push rod on the 2nd hole. You need 1/16" annealed brass tubing horse shoes to bush the .031" uncoated lead outs through the plastic. When you wrap the ends with 26 gauge copper wire the wrap needs to be 3/4" long and don't solder or glue it or you'll make a hard point, just wrap it tight. Brodak also sells the adjustable lead out guides which are nylon. If using wire push rods, wire should be .075" and you'll need a fairlead on the elevator rod.
MM
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I'm guessing that the coating on the wire, if that is what you are using, is soft and very flexible. That said when it is passing through a metal or plastic guide hole it may want to stick. That will cause untold frustration when flying. If you use a wood leadout slider that wont be a problem. Make doubly sure that the leadout wires are free of the rib cutouts through the full travel of the slider.
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I did a quick search on here under bellcrank leadouts and at least 25 threads came up.
All the above is good advice but read these threads and do it correct. Do not use coated wire as it will bind at the leadout guide as it wears. What you have done will work but it is prone to failure if your plane last a long time. I have used stainless fishing leader for leadouts in a pinch but it is hard to work with. Also use heat shrink tubing on the wire wrap not glue.
Ed
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Maybe others will disagree with me here but I would not loop the lead out wire thru the bellcrank as shown in your photo. Under load, that loop of wire will tend to flex, or "flatten out", then relax as load is removed. This repeated flexing can fatigue the loop and lead to failure. I have seen many like this last far longer than I thought they would, but then again, I have seen some fail rather early. Very hard to predict. On something the size of the Banshee you might be OK but for future projects there are better ways to do this.
I use a nylon (delrin?) lead out guide. I have always worried about the stranded lead out cables eventually sawing thru the nylon but it would probably take many flights to do that. And, I worry about individual strands of the cable breaking due to rubbing on the guide, especially if the guide is a brass tube or eyelet. I have used solid leadouts and with the nylon guide there is almost no wear, no sticking. But, solid leadouts have their disadvantages as well.
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Honestly, if you're going to get serious about learning the pattern it'll be kindling long before you wear anything out. I hope you feel all encouraged now.
If you let people talk you into redoing the leadouts, order some 1/16" OD copper or brass tubing and a pair of round-nose pliers from Amazon. I use that for both ends of the leadout, both at the bellcrank and at the outside end. Pictures here: http://stunthanger.com/smf/building-techniques/build-cartoon-scale-mooney-mite/msg435630/#msg435630 (http://stunthanger.com/smf/building-techniques/build-cartoon-scale-mooney-mite/msg435630/#msg435630).
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Ok. Thanks again all for your help and suggestions. I have noted the information put forward for future builds, as it was already installed as was pictured. I am by no means a competition flyer, just the odd time for fun. Mainly at the cottage the odd weekend, so say for example I may do 1 tank every couple of weekends. It is just for fun. If I am to get more serious, I will most definitely employ the above mentioned suggestions. Thank you.
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One other quick question for the more informed. Since not a competition stunt ship, mainly to fly standard round circles in the upright position, and maybe the odd wingover, where would the control rod to the flaps be best positioned? Standard Sig bellcrank furnished with the kit, and I have 2 holes to choose from. I currently have it installed in the outer hole, as per what I have been doing with my 1/2a stuff. Thank you again.
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Honestly, if you're going to get serious about learning the pattern it'll be kindling long before you wear anything out. I hope you feel all encouraged now.
Funny, but true. I lost count but think I re-kitted 5 or 6 planes so far.
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The push rod wants to be in the hole closest to the pivot bolt.
MM
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Ok. Will do the change then. Thanks.