Wing Ribs Lightening Hole Diameters

[markcr]

Sorry for posting so many questions. I'm a new builder and trying to gain as much knowledge as I can BEFORE I start working on the project. I've noticed that the plans do not include diameters for any of the lightening holes in the wing ribs. How do I determine what size to make them? If I make them too big, I suspect I will jeopardize structural integrity of the rib. Too small and the part then becomes heavier than designed. It seems like this would have been a simple measurement to include in the drawings but for the life of me, I can't find it.

[Bcone1381]

I don't think you'll find the measurement. I measured the lightening holes on the plans for the Patrol and then doubled it to get the actual size of the lightening hole (since the drawing was 1/2 scale). I assume it's similar for the LSA.

[markcr]

Thanks. I'll give that a try. At the bottom of my page 3 rib drawing it says, "SCALE DRAWING FOR DIMENSION NOT SHOWN". I think that was throwing me off. However, I do see the scale1=2 in the lower right corner. Still getting used to reading and interpreting plans. Hope my LSA doesnt end up the size of a Sea Fury!

[N3UW]

Thanks. I'll give that a try. At the bottom of my page 3 rib drawing it says, "SCALE DRAWING FOR DIMENSION NOT SHOWN". I think that was throwing me off. However, I do see the scale1=2 in the lower right corner. Still getting used to reading and interpreting plans. Hope my LSA doesnt end up the size of a Sea Fury!

Make sure you pick up a set of engineering scales. they make reading the scalled drawings much easier.

[sjt]

You might look at a flexible scale:

http://www.yardstore.com/browse.cfm/4,4411.html

There are smaller sizes too. This ruler has fractions and decimal sides. I found it useful when laying out the locations for rivets on the rib flanges (1.5" on a patrol). Since it is flexible , you can just lay it on flange and bend it around form marking rivets.

Some of Bob's dimensions are in fractions, and some are in decimal.

[BTAZ]

Since the scale is 1:2, I just put a compass across the diameter of the drawn holes as that was the radius of the finished holes.

[Chris In Milwaukee]

Now there's a smart idea!

[markcr]

Thanks for all the good input. I'm getting much better at deciphering measurements off the plans now. Typical first time builder stuff. Oh, and whover it was who tipped me off to Aircraft Spruce's option to roll the aluminum, thank you SO much. My shipping ended up being $35 instead of $165! This week I've been getting my router table built and am just about ready to actually cut some ribs!

[SpruceForest]

On the Patrol, the 1:10 main spar plans sheet notes 5" typical, but the detail at 1:2 shows a 5.5" diameter... we just went with 5" unless otherwise noted for main spar.