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Building Tips and technical articles. => 1/2 A building. => Topic started by: Mark Mc on October 03, 2020, 02:17:14 PM
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I’ve been saying for a long time that I need to make a 1/2A size incidence meter. I finally decided to make one up. I started by going to the local hobby shop and picking up the two largest sizes of K&S square tubing. I verified the second largest fit tightly in the largest. Then I pulled out some paper and drew out what I thought would be good.
(https://i.postimg.cc/d0PM2b4p/SH1.jpg) (https://postimages.org/)
I then transferred the measurements to some 3/32” ply and cut a 4” section of the larger tube.
(https://i.postimg.cc/MHrNvNns/SH2.jpg) (https://postimages.org/)
I cut out the frame and glued the tube to the top of the frame.
(https://i.postimg.cc/PJq0fT5p/SH3.jpg) (https://postimages.org/)
(https://i.postimg.cc/fWH62t8x/SH4.jpg) (https://postimages.org/)
I slid the smaller tube back in to check everything, then cut the two halves apart. Next I cut the angles for the leading and trailing edges of the wing. I also put a dimple in each outer tube to ensure there was a good friction fit.
(https://i.postimg.cc/ZqrGVwQR/SH5.jpg) (https://postimages.org/)
(https://i.postimg.cc/zB791V8Y/SH6.jpg) (https://postimages.org/)
(https://i.postimg.cc/ZR41grkL/SH7.jpg) (https://postimages.org/)
I cut another piece of tubing and glued a bubble level to it, verifying the level matched the level I use for the tail surfaces and the prop fixture.
(https://i.postimg.cc/wT7nSqrn/SH8.jpg) (https://postimages.org/)
(https://i.postimg.cc/gkQ1d9Fj/SH9.jpg) (https://postimages.org/)
(https://i.postimg.cc/43TM7z3T/SH10.jpg) (https://postimages.org/)
Perfect size for 1/2A:
(https://i.postimg.cc/rw43whMJ/SH11.jpg) (https://postimages.org/)
Mark
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Well, I keep calling this an incidence meter. More like a level gauge.
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Well, that's pretty slick. You just need one for the engine, made out of that same aluminum angle you have sitting in that one pic. Attach it to the engine where the prop mounts, add the level or have it glued to it. If the bubble goes from line to line, and you manage to match the two, I would say your incidence is zero compared to the thrust line. You can just set a level on the horizontal tail. Mark the levels with some sort of fin line graduations every 1/16" just for refeence. With experience, you will be able to split the hairs pretty good and hit those 1 and 2 degree settings.
Thanks for posting,
Dan McEntee
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Dan, that's what that aluminum angle is for. One side has a hole drilled for .049 prop screws, and the other is drilled for .09 prop screws. The small bubble level is set on the angle after the angle is screwed to the engine drive plate. Since I only use flat stabs at this point, the small level is also set on the stab, that way with the wing bubble level, the small level is just moved from stab to engine fixture to ensure everything is level to each other.
Mark
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Where do you get the small levels? I don't know if I have ever seen anything like those in the places I shop at most.
Type at you later,
Dan McEntee
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I don't remember exactly where I got the smallest one. I know that it was in a package of accessories with something I bought that needed hanging. You know like how when you buy a piece of Ikea furniture, they throw in cheap wrenches to assemble t? This was something that needed a level to align. My normal source of bubble levels is the Dollar Store. You buy their $1.00 level, and then break it apart for the bubbles. I'm usually bad and break the level apart, put the three bubble levels in my pocket, and throw the rest in the trashcan in front of the store. That's the source of the level I glued to the tubing. A dollar gets you three bubble levels.
Mark
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Harbor Freight Line Level: https://www.harborfreight.com/search?q=line%20level $1.50 or so