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Building Tips and technical articles. => Building techniques => Topic started by: Jake Moon on March 26, 2024, 09:58:09 AM
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Just what we all need, another Twister thread!
I have a single plane that I fly regularly. It's a Brodak Vector 40 ARF with an LA 46—excellent stuff. I'm not working for the time being and have the control line bug, so I've recently learned the pattern and put in 8-12 flights a week. Knowing that any day could be that Vector's last, I figured having a backup plane wouldn't be the worst idea. Here's the Vector and our flying setup in a park by the water:
(https://i.imgur.com/nuKKY6Z.jpg)
Though my Twister is under construction, it's already flown a lot. I bought a couple SIG Twister kits from a hobby shop in Japan and had them sent to my mother in Tokyo. On a recent trip to visit her, I took the kits back with me to Singapore in my checked luggage. We live in a small (by American standards) apartment, so I've been building this plane on our desk, the floor, and our balcony. In order to build a straight wing but also not destroy our desk, I went to our local hobby shop and bought a few pieces of heavy, 6.5x100x1000mm C-grain balsa to use as my jig. I cut about 40 tabs and glued them to the wood slabs and the trailing edge and spar. Here's the setup mid-build:
(https://i.imgur.com/7HCFH1O.jpg)
I cut the half-ribs from extremely light 1.5mm wood. Good, light balsa is easy to find in Singapore and surprisingly cheap. It might be the only cheap thing here! This is fortunate, as the kit wood is very heavy.
When I build scale models, I make things more complicated than they need to be in the quest to do something different or just to see if it'd work. Turns out that is also the case in aeromodelling. I wanted to go for a warbird that wouldn't look absolutely ridiculous with a long nose and a straight, mid-mounted wing. And I wanted to be different than the usual P-51s, Zeros, P-40s etc. I landed on the Macchi C.205 Veltro. The moments are roughly similar, the fuselage is shallow, so the mid-mount won't be as weird, and the wing doesn't have a huge taper. And I'll get to do a fun livery.
(https://upload.wikimedia.org/wikipedia/commons/5/52/C.205V_352_Sq_20_Gr.jpg)
Here are some of the Fancher modifications (before filling). I replaced most of the aft fuselage in an effort to reduce weight (the kit fuselage wood was around 15 lbs/ft).
(https://i.imgur.com/mfl9nCN.jpg)
(https://i.imgur.com/hqQl43i.jpg)
After each building session everything goes back into my closet. Some details in this photo show that I made the fuselage narrower to make it more scalelike and the 3-inch bellcrank instead of the 4-inch one that the plans call for but I can't get a hold of here.
(https://i.imgur.com/IxQ9qk6.jpg)
Covering options are also limited here. I have some polyspan-like covering made by KM Co. in Japan. I've never used this stuff before so I made a little mockup to see if it'd shrink and soak up dope. It came out pretty good! Shrinks drum tight and strong. Like polyspan it doesn't sand well. And unfortunately it's very heavy. For 1 wing the covering alone weighs 1.2 ounces! So I only covered the wings, rudder, and elevators.
(https://i.imgur.com/x0XB5G1.jpg)
My wife took a picture of a late-night doping session on the balcony. Waterbased EZ Dope is the only dope available here. So far I like using it.
(https://i.imgur.com/JY6tOW6.jpg)
Wing covered. Eagle-eyed viewers may note that the bays are off by a half. I cut the leadouts too short and ended up with an outboard wing 1.5 inches longer than the inboard. So I sawed off half a bay from the outboard. Whoops.
(https://i.imgur.com/ruQ8POp.jpg)
Assembly time. We don't have a table or desk large enough for this, so I'm building it on the floor and using the joints in the hardwood as the centerline. It's working though my knees are getting sore! I enlarged the stab per the plans, though cutting away some for the rounded look probably reduced the area back to the kit size. I made a built up stab that warped, so I made a replacement out of 6.4-pound, C-grain, 6.5mm wood.
(https://i.imgur.com/FAbBztf.jpg)
And then today I glued in the wing! This is my favorite part of the build and it took all of my self-control not to pick it up and look at the assembled airframe while the epoxy still dried. I have realized that something is slightly off—I could only get the measurements within 2mm of each other on each side. The wing is at least straight to the fuse and level to the floor. I'm hoping that'll be close enough.
(https://i.imgur.com/8RxAyrR.jpg)
(https://i.imgur.com/pEjnhmc.jpg)
More updates will follow soon. As it sits, the airframe consisting of the covered wing, doped fuse, stab, and rudder is 19.2 ounces. Power depends on a few things. If I crash the Vector and need to get the Maccherized Twister flying well ASAP, I'll use the LA 46 from the Vector. If it comes out too heavy, I'll go for the LA 46 as well. If I don't plant the Vector and can take my time, and the Twister is light enough, I have a new K&B .28 Sportster that looks cool.
Thanks for taking a look.
Jake
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Thanks for the report!
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Thanks for the report!
Looking good. I love the plane you are patterning it after. I designed a PA ship around it back in the 70's. Never built it.
Ken
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Nice!
The best thing about storing the plane parts in the closet between sessions is that your clothes smell like balsa wood all day.... Waaay better than a dryer sheet!
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Keep up the great work and stay with it! You are getting there.
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Brings me back to the days of building in my dorm room during college. Great report as always!
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Brings me back to the days of building in my dorm room during college. Great report as always!
Did your roomate complain most about the smell or the dust? I taught mine how to hand launch and pit for combat. LL~
Ken
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Thanks to everyone for the replies! The theme of this update is sanding. I do almost all of the outside jobs (sanding, filling, doping etc.) at night when the weather drops from 95 degrees and 90% humidity to only 83 degrees and 90% humidity.
Balsa filler is not available in Singapore, but I found a substitute in model railway putty. I looks, weighs, and sands the same, and is annoying to apply. I think it's the same stuff. After filling, I sanded the filler sections with 240, 320, 400, 600, then 800-grit sandpaper. Non-filled areas started the process at 400. Here's the airframe now.
(https://i.imgur.com/aecoGui.jpg)
I foolishly used the filler for filets as well. This proved to be impossible to get perfect as I kept gouging the filler or getting it uneven or standing too much of it away. Eventually I just called it a day. Part of the intent of this project was to learn how to build, and I certainly learned here.
(https://i.imgur.com/Owcm6Vk.jpg)
I made the fuselage/rudder transition piece (what on earth is that thing called?) from 3mm balsa and glued it in place.
(https://i.imgur.com/cfdMqt1.jpg)
Here's a little detail that I'm pretty pleased with: the shroud that the tailwheel would retract into during flight.
(https://i.imgur.com/yLw5ZXq.jpg)
The fuselage fun and filler added 0.4 ounces, so the airframe now sits at 19.5 ounces.
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Jake, you should be able to get wood filler at a hardware store. "Plastic Wood" works great but is a bit heavy. Min-Wax makes a light wood filler that is pink. It turns pine color when it dries. It sands really well. Love Twisters. I will warn you that they don't glide well after the engine quits which makes the F2B landing a challenge!
Keep it up - Ken
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Excellent work Jake!!
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Very nice work Jake
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Thanks for the kind comments. A big update - we have paint! I went for the standard sand with green squiggles that the Italians employed on most C.202s and C.205s. I used some Nippon Paint rattlecans from a hardware store as that is all I can manage with my setup at the moment. The green is just acrylic art paint applied with a brush. In the future I'll certainly need to figure out some sort of airbrush system as this isn't great paint and is quite heavy. Since the color covers well, I did not prime the airframe. Even still, all the color added 3.5 ounces. Ouch!
(https://i.imgur.com/ZpsCcCJ.jpg)
(https://i.imgur.com/R65eECv.jpg)
(https://i.imgur.com/NnTYqYs.jpg)
The airframe is now 23 ounces. My new target number for the completed plane is 44 ounces. I recently bought a Brodak .40 that I'll use instead of the K&B .28 I had planned to used, so that should give me a whole lot more power for minimal weight gain.
My next step will be to design some vinyl applications for the roundels and squadron markings. We live near an art school so there are about a dozen print shops who can cut vinyl within a 10-minute walk.
Thanks for looking,
Jake