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-   -   Rear Spar Doubler Plate (https://vansairforce.net/community/showthread.php?t=165500)

RV3Kev 10-29-2018 05:32 AM

Rear Spar Doubler Plate
 
Dear Guys

I'm working on the rear spar for a set of recent RV3B wings. The plans call for a doubler plate where the inboard aileron bracket is mounted.

The plans seems to be a little confusing about the location of the rivets that will be eventually used for the inboard aileron bracket and the doubler plate.

The plans (Drawing 7) call for the lowest rivet to be 5/16 from the bottom of the rear spar. If I use the 5/16" from the very bottom of the rear spar, then it would fail to meet the ED requirements for the doubler plate (e.g. /4") by along way. (Note that the bottom flange is bent to 95 degrees not 90)

The plans don't seems to have to have the correct bend for the bottom of the rear spar. Assuming that 5/16 refers to the bottom end of the bend radius, then it still doesn't meet the ED requirements of the doubler plate (misses a little bit).

The doubler plate as supplied is exactly 3" deep but the plans call for a doubler plate that is 3 1/8" deep. ??

Has anybody else noted this problem ?

This is important as the holes will be used for the aileron bracket later on. I have also noted that the top hole of the 5 rivets needs to located a lot lower that in indicated in Drawing 7 to achieved a 1/4" ED for the angle use to attach the aileron bracket.

HFS 10-29-2018 07:02 AM

Drwg 7 - Circa 1984
 
My drawing #7 doesn't have any "call outs" for rivet spacing at all - left up entirely to the builder!

HFS

Rv3Dave 10-29-2018 07:11 AM

The doubler plate flange is on the top so the 95 degree bend is correct to match the spar top flange. It nests behind the rear spar, flange up. I seem to remember that my 306 E and F doubler plates were too tall and I had to trim them to match the rear spar dimension but I don?t remember if they were 3 1/8 or not, they just need to fit the rear spar once nested behind the spar. If not vans will replace the part. I had at least one wing part mis manufactured (too short by 1?) and vans sent a replacement. 5/16 edge distance is not a problem with AN4 rivets.

RV3Kev 10-29-2018 02:41 PM

The top flange is bent though 98 degrees to form a 82 degree angle to match the slope of the top skin. The bottom flange is bent through only 85 degrees to form a 95 included angle. The details can be found on the left hand side of drawing 5.

The rivets on the inboard and outboard sides are easily located to maintian edge distances. With doubler 1/8? short, the rivets need to be 1/4? from the edge of the doubler rather than 5/16? from the bottom rear spar flange in order to maintian ED.:)

The problem locating the holes for the aileron bracket is trying to maintain ED on the doubler and the aileron bracket mounting angles especially on the shorter one.

Rv3Dave 10-29-2018 03:48 PM

You may have to adjust the flange angle on the doubler to get a better fit. Truth is, the rv 3 parts, even the 3B wing kit, do not always fit out of the box like the newer kits do. I suspect you will run into a lot of places where the plans and the parts do not match, even find places where two drawings show different deminsions for the same part. You really have only three options, modify what you have, get a replacement part from vans (and hope it fits better) or make your own part.

RussellT 10-29-2018 08:20 PM

I don't recall any issues when I did mine (it was a long time ago though). Whenever I see "Typ" noted on any of the drawings I take that to mean your actual measurements/placements may vary? I did need to raise the height of the pushrod hole to get clearance at final fitting, I would suggest leaving this hole undersized and enlarge as required later on.
[IMG][/IMG]

RV3Kev 10-30-2018 05:40 AM

The top flange is bent though 98 degrees to form a 82 degree angle to match the slope of the top skin. The bottom flange is bent through only 85 degrees to form a 95 included angle. The details can be found on the left hand side of drawing 5.

The rivets on the inboard and outboard sides are easily located to maintian edge distances. With doubler 1/8? short, the rivets need to be 1/4? from the edge of the doubler rather than 5/16? from the bottom rear spar flange in order to maintian ED.:)

The problem locating the holes for the aileron bracket is trying to maintain ED on the doubler and the aileron bracket mounting angles especially on the shorter one.

RV3Kev 10-30-2018 05:54 AM

A possible solution
 
It seems that Van?s use the same press to make both the rear spar and the doubler plate as the top bends are identical when placed side by side. (Technically they need to be slightly different with doubler having a slightly smaller radius, but in reality, not enough to matter). I have a scrap rear spar that I can cut a new doubler with the correct dimensions many times over.

Thought?

Rv3Dave 10-30-2018 06:09 AM

I see no problem making doubler from your scrap spar. Build on!

RV3Kev 10-31-2018 04:22 AM

Made a new doubler from the scrap rear spar.

The new one on the right is made according to the plans ie 3 1/8? the left one is as supplied.





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