Laying Out Rib Stitching (Top to Bottom)

[LSaupe 123]

Getting ready to rib stitch and see that I just cant lay out the same distances on the top vice the bottom (as I had hoped), due to the significant differences in arc length.  How do you guys typically hadle this?  At first pass I am thinking about laying out the bottom and them thansferring the top holes by putting a pointer through the bottom holes with a device to keep the pointer normal to the bottom surface.

 

How is this typically accomplished?

[EDMO 1078]

We went by AC43-13 for stitching the Piper, which calls for 2 1/2" between stitches in the prop blast area, and 3 1/2" between stitches on the rest of the wing. I understand that to be on the top of the wing where stitching actually keeps the fabric from ballooning up from the rib. The first stitch should be 1/2 of the proper stitch distance from the leading edge on top.

Quote from AC43-13: "The prop blast area is considered the diameter of the prop plus one rib." Please don't ask me how to figure this out. (prop diameter each side? or 1/2 for each side? or measure from middle of fuselage??)

I guess experimentals don't have to go by AC43-13, but it is good practice.

We laid out our hole patterns on the top, and then took that number of holes on one side of the rib and divided the chord of the bottom by that number, getting the dimensions between holes on the bottom. (maybe number of spaces works too?)

Making a template for top and bottom makes the rest of the holes go in faster.

Hope this is clear.

EDMO

Edited 5 Mar 2015 by Ed In Missouri

[EDMO 1078]

Is this the wings that have already been painted?

Are you going to use reinforcement tape before stitching, and then cover with finish tapes?

If so, I think you need to cover leading edge of finishing tapes with new leading edge tape also.

Looks like some touch-up painting to be done too?

EDMO

[LSaupe 123]

Thanks for the replies, great info.  Wings have not yet been painted, si it does help things a bit.  Yes, will bve using reinforcing tapes and new finish tapes after.

Edited 5 Mar 2015 by LSaupe

[High Country 69]

Just remember right from the start that these planes were originally designed to not be stitched thus the wide capstrips so don't worry to much about it being perfect. that said I did as Ed suggested and went with the layout for AC 43.13- the poly fiber manual is well worth buying regardless of what process you are using. Make a template of the rib and mark your stitch spacing out on it first then just transfer them with a square to the other side. keep your stitches straight so it doesn't pull the fabric. Its a lot easier than most make it out to be until they have done it. good luck

[EDMO 1078]

Just remember right from the start that these planes were originally designed to not be stitched thus the wide capstrips so don't worry to much about it being perfect. that said I did as Ed suggested and went with the layout for AC 43.13- the poly fiber manual is well worth buying regardless of what process you are using. Make a template of the rib and mark your stitch spacing out on it first then just transfer them with a square to the other side. keep your stitches straight so it doesn't pull the fabric. Its a lot easier than most make it out to be until they have done it. good luck

I agree - rib stitching started with old narrow wood and aluminum ribs - Probably when they only had fabric on the top of the wings.

As far as I know, there has been no reports of any fabric separation with proper gluing of these wide capstrips on our slow flyers.

Some folks seem to think the plane is worth more with the stitching - I don't.

EDMO

Edited 6 Mar 2015 by Ed In Missouri