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Building Tips and technical articles. => Building techniques => Topic started by: Jim Roselle on January 30, 2014, 06:00:18 PM
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Hey all,
I've started building a Fancherized twister to be powered by a LA .46 and I have a few questions. My first question stems from the fact that the leading and trailing edge supplied with the kit were bowed. In the Fancher article he replaced the leading edge with spruce. I just purchased arrow straight basswood for the leading AND trailing edge. This will add 1.8 oz over the kit wood. I am also newish to control line and may have some unplanned landings, so the added strength may be desirable. Thoughts?
Question two:
What do I use as an installation tool for these and do I need to sink them further than flush with the surface? Should I epoxy them?
(http://i.imgur.com/jwmnJj5.jpg)
Question three:
I am using this type of gear for ascetics and for ease of replacement after botched landings.
(http://i.imgur.com/kuVxKfr.jpg)
Do I need to add a hardwood mount between the ply doublers. The ply seems a little soft and I would hate to elongate the mounting holes with a hard landing.
Thank you for any and all input,
Jim
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Best option is to design it to be easy to repair. The bass wood isn't a terrible idea and it will be more robust. Not sure why you want the threaded inserts?
I use that same gear on Flite Streaks and Ringmasters it works well. I suggest you do use hardwood bearer for the gear ... Twisters fly well and are fun if you keep them light.
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Best option is to design it to be easy to repair. The bass wood isn't a terrible idea and it will be more robust. Not sure why you want the threaded inserts?
I use that same gear on Flite Streaks and Ringmasters it works well. I suggest you do use hardwood bearer for the gear ... Twisters fly well and are fun if you keep them light.
I've heard that inserts are better than blind nuts for engine mounts. I've never used them, I'm open to others experience and advice.
Jim
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Al Rabe uses the threaded inserts on his Bearcats. Good enough for him, good enough for me! H^^
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Al Rabe uses the threaded inserts on his Bearcats. Good enough for him, good enough for me! H^^
I don't know Glenn?
Those things need more material removed to be put in place.
"T" nuts or "blind" nuts, until something better comes along, I'll continue to use them.
Washers and lock nuts if you want less material removed.
IMHO
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I use washers and plastic insert lock nuts when mounting the engine. Anything else and you have to rely on that tiny split ring lock washer, and I have a hard time trusting those.
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I have used the threaded inserts when I changed engines and had different mounting holes. Plugged the old holes and drilled for inserts to avoid swiss cheese engine bearers.
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I've been using the brass (bronze) inserts for a while now and I like them a lot. Here's my procedure:
Drill the appropriate size hole. Then with a tooth pick I place epoxy in the hole- not to much. (Experience will let you know how much) Then with a 4/40 cap head bolt, washer and a nut (preferably a plastic lock nut) tightened down on the insert I screw it into the maple MM. Now the trick comes: Hold the cap head bolt with an allen wrench while loosening the lock nut with a 1/4" wrench. Bolt comes right out. This set up can be slightly sunken into the mount and works really well. When the epoxy has cured I run a 4-40 tap through the insert to remove any unwanted epoxy.
I'd take a picture but I'd have to remove my engine and that isn't going to happen since I'll be flying it tomorrow and I don't want to screw anything up unnecessarily! LL~
Hope this helps, Jerry
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Hi Jim,
I just finished my Fran Twister last week. Haven't been flying yet, field is covered with snow. I didn't try the brass inserts but may on my next build. Everything went pretty smooth once Sig sent me a new fuselage, the first one had a pretty bad bend in it. On another note i'm using an OS 35FP. I'm not hte most smartest guy on these boards but the LA46 may be a little too much engine. The Twister is not the biggest profile out there and they don't come out too heavy. I used the 35 on a Dare profile Smoothie last year, it is about the same size as the twister and it was plenty of engine. I have a LA46 but I'm saving it for my next build which will be a pathfinder or Cardinal. Thes two have a lot bigger wing and fuselage. I'm not trying to change your mind, but I would ask someone with more knowledge than me about your choice. An overpowered ship can be a pain to slow down.
good luck,
Rich
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The LA 46 has a reputation for being able to fly a wide range of planes. I can't vouch for that personally, but my plane with an LA 46 is a 52 ounce (I worked hard) Fancherized Twister, which does just fine.
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Rather than using inserts or having clearance holes for the bolts in the motor mounts, just tap the maple mounts directly. Use a 2 mm drill for the tap drill then rub candle wax on the tap to lubricate and go at it. It's the lightest (no blind nuts, no inserts, slightly shorter bolts) and easiest way to mount an engine and the bolts never loosen.
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Rather than using inserts or having clearance holes for the bolts in the motor mounts, just tap the maple mounts directly. Use a 2 mm drill for the tap drill then rub candle wax on the tap to lubricate and go at it. It's the lightest (no blind nuts, no inserts, slightly shorter bolts) and easiest way to mount an engine and the bolts never loosen.
I really like that idea, but installed the inserts about half an hour ago. Will keep it in mind for the next build.
Jim
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I really like that idea, but installed the inserts about half an hour ago. Will keep it in mind for the next build.
Jim
The Twister is a great model for only 49.00. Sig has them on sale.
Will you post photos of your Twister build?
Charles
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While the Fancher mod's increase its performance, the basic Twister is a fine flying design for newcomers.
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Just a note for the next build:
When using blind nuts (which have worked fine for me), I usually use hard, but thin plywood doublers. These will crush the balsa inward on landing gear attachment; so I usually insert 1/4" harder dowel through the balsa, before laminating the plywood, although epoxying it through the plywood afterwards should work fine. This takes only a few minutes. Then just drill through the dowels for the 4-40 l.g. attach screws.
I never took a photo of this process on a fuselage (I do it on elevators for the horn attach), but the photo below shows two approaches. The top fuselage has two CF extrusion inserts all the way through the plywood. I haven't finished that plane and don't know yet the wisdom of this approach - might not be the best way to do things. The lower and current fuselage has one l.g. hole through the hard-wood engine bearer and the other yet to be drilled through a dowel just below the center line. That fuselage is finished now, but only fit to wing and stab - not yet glassed and attached. The second shows how easy it was to do this for an elevator.
SK
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Thanks Serge,
I put a 1/2" mahogany hard point for the gear.(http://i.imgur.com/px9d3Y5.jpg)
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If you decide to use "t-nuts" or "blind nuts", use DuBro. The cheap ones can pull apart. I prefer T-nuts over the threaded inserts, because they leave more wood in the beams. Tapping the maple is an interesting idea, tho. y1 Steve
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What's best to use for an axle on this type of gear?
(http://i.imgur.com/kuVxKfr.jpg)
Thanks,
Jim
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4-40 bolt with nut and jamb nut.
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4-40 bolt with nut and jamb nut.
That's what I figured, thanks.
Jim
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I use 6-32 bolts with brass tubing inserted into the hub. I've had too many 4-40 bend locking up the wheel.
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http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXD822&P=0 (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXD822&P=0)
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Did you see mine? Did you see mine? I just finished it the other day, and cannot go flying due to snow, cold and wind, So, I scratchbuilt a profile P-40 from plans, and am now finishing a Sterling Flying Fool, to keep me busy, 'til the weather gets on the right track. See of they'll stick here...(http://[img])[/img](http://)
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http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXD822&P=0 (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXD822&P=0)
Tim...Those are really heavy. I go to the industrial fastener store and get 6-32 "button head" socket head cap screws. I look for a "grip" length that will suit the wheel hub thickness, and use two elastic lock nuts, one on backwards and one on correctly, on each side of the aluminum, and two flat washers, each side of the wheel. Cut off the excess threads, file off any burrs, done deal. They look pretty decent, by comparison to the R/C axles, and are plenty strong.
Howard glues 1/8" CF tubing into his CF LG legs and uses a washer and a tiny hitch pin to retain the wheel. Depends on how good...and how serious you are. Maybe not for everybody! H^^ Steve
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What's best to use for an axle on this type of gear?
I have been using 4-40 hardened engine mounting screws for many years on the Skyray and so far, they have taken a licking and kept on ticking.
Brett
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Howard glues 1/8" CF tubing into his CF LG legs and uses a washer and a tiny hitch pin to retain the wheel. Depends on how good...and how serious you are. Maybe not for everybody! H^^ Steve
I don't think I land that smoothly. At least not consistently.