Eagler's Nest
Airframes => Single Seaters => XL => Topic started by: bmxmann on April 17, 2017, 09:24:10 PM
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So, I messed up a bit on the fuselage, and looking for opinions.
The first diagonal brace on the bottom after the Number 3 station (going back) should be a 1/2 inch tubing, well I used 5/8. I used 1/2 after that as I should have. I do have all the lower braces already tacked in, and am currently at step 10 of Scotts Excellent write up on the frame build, and just happened to notice this now. Some of my tacks are pretty.... big, and this being pretty far up in the frame I feel it would be a PITA to get out and to get a 1/2 inch one to fit right. Not the end of the world... just a pain. I am already starting to talk myself into cutting it out and putting in a 1/2... just a bit worried I could mess up one of the long stringers in the processes. I do not yet have the vertical braces at the number 3 station in yet, so better that I caught it now than later.
So I my question is... Should I cut out and replace with a 1/2, or leave it as-is and run with the 5/8th? Its about 3ft in length, so I imagine there is a bit of a weight difference.
Funny thing (trying to stay in a good mood) is I actually messed this up long before I even got the material. I had gone through the plans with a highlighter and marked the 5/8 in purple Highlighter, and the 1/2 in yellow. I even realized at the time I messed it up, so I marked 1/2 with a couple arrows at that brace and ran over it with some yellow (so it basically still looks purple). Figured I would remember and also see my arrows and what not... nope.
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Aircraft Spruces' info on 4130 shows that the difference in weight would be about 2.26 oz.
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Sounds like it's part of your Eagle now (-:
I'd leave it and move on.
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I would second that, leave it and move on.
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Plan A: A teachable moment without great consequence. Leave it in.
Plan B: Replace the last few support tubes with 7/16 or 3/8 tubes to compensate.
Plan C: Fill all the hollow space in the wings with bags of helium. While the overall mass of the vehicle won't change, it will fool the scales of the FAA inspectors. This might allow for a slightly larger engine.
(https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Allison_1710-115_V12_Aircraft_engine.jpg/800px-Allison_1710-115_V12_Aircraft_engine.jpg)
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So, I messed up a bit on the fuselage, and looking for opinions.
So I my question is... Should I cut out and replace with a 1/2, or leave it as-is and run with the 5/8th? Its about 3ft in length, so I imagine there is a bit of a weight difference.
BMX- as stated by others, this is simply not a snafu, to worry about...but to give you a more cozy feeling about leaving it.
unless the frame was damaged, cutting out a (mid-tube) is rarely easy..but sure would give you an idea on how strong tacks are.
I have repaired a few frames for others, that have started cutting out tubes (though mostly completely welded-clusters) and often more damage is done to non problem tubes than what is gained by replacing the tube.
The simple reason is if they grind a weld out, invariably the grind gets into the good tubes.
If you have cross station in, or diagonals in- then it makes it pretty hard to insert the new tube for the old tube unless one end or the other is made somewhat sloppy to get it to fit. Just the mechanics of it.
Wondering if you made something a bit stronger than required, is far less stressful than always thinking you made something to weak... Everyone can accept the first, no one should accept the second.
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Thanks for all the responses!
My initial thought was to just leave it and not worry, but then figured I should check with the group here and see just in case there was something I was missing!
Looking through the plans Vince laid out... C seems like a pretty good one though!