Need Measurement

[Jim Herpst]

Would someone please provide me the rear spar opening dimension of a BC12 Rib. I am more interested in the height as I have a Jig From the L2 I built wood ribs for and am attempting to use it for a start of a clipwing. (doing it the Old EAA way really cheap starting by building ribs with the proper sized Cap strip and plywood I already.) have. Also if there is a gap between the spar and the Rib (height wise) my assumption would be that is at the TOP when the rib is positioned on the spar.

Already have the Spruce spars cut and sized as a swick except using the elliptical wing tip. This is a long term deal and is for the adventure of re creating something a bit unique.

Thanks in advance Tribe. I am glad to be back here posting !

[Hank Jarrett]

Re: Need Measurement

If I am understanding you right you want to know the gap between the top of the spar and the rib cap strip bottom in the slot for the aft spar. The thing is that IS NOT a constant! If the spar has a slight curve the top gap will get smaller where the spar curves up and wider when it curves down. The trick is to get ALL of the ribs on with none of them touching the spar top or bottom and all of the RIBS lined up. If you have a PERFECT spar (good luck) split the difference top and bottom to get even spacing. That AIN'T going to happen.

Hank

[LostnSpace]

Re: Need Measurement

Hank, PM sent

[Guest]

Re: Need Measurement

Does this help?

I would say rear spar opening is 5".

[Jim Herpst]

Re: Need Measurement

Hank/ Drude Thank you both! Hanks reply raises another question... what is the front spar opening dimension? Also if If I understand you correctly ,Hank, is it both spar openings where the rib when mounted should have a gap on the top and bottom? One last double check.. what is the distance between the rear of the front spar and the front of the rear spar ? My understanding was the wing size of the DCO/65- L2 and the B series were the same.. sans the spar size.....

Thank you again you two!

[Robert Lees]

Re: Need Measurement

Hank/ Drude Thank you both! Hanks reply raises another question... what is the front spar opening dimension? Also if If I understand you correctly ,Hank, is it both spar openings where the rib when mounted should have a gap on the top and bottom? One last double check.. what is the distance between the rear of the front spar and the front of the rear spar ? My understanding was the wing size of the DCO/65- L2 and the B series were the same.. sans the spar size.....

Thank you again you two!

The spar centres are 31 +/- 1/32. I'd suggest that is a more important dimension?

[Hank Jarrett]

Re: Need Measurement

The gap in the rib for the spar is TIGHT on the spar. If you slide the ribs down the spar without flattening the metal where the old nails held the rib to the spars it will put a NASTY scar down the length of the spar where you slide them. That scratch is often mistaken by those who don't know what they are looking at (Cessna type A&Ps and IAs) for a split spar! Make sure the metal around the nail holes doesn't damage the spar. I seriously doubt it does that much REAL damage to the spar, but being told you have to replace the spar because the varnish has a scratch is more heart burn than you need. The gap in my ribs measured about 0.8". My spar was easier to get a caliper around and measured 0.78" thick.
As for the top and bottom gap it will vary depending on how straight your spars are. If your spars have a lot of curve (a lot of spar curve is NOT a lot of curve!) you could have NO gap on the end ribs on top and no gap on the bottom on a middle rib. The gap does not matter. What matters is that the tops of the RIBS are in a straight line. You move the ribs up or down to get the RIBS aligned, not the gap even.
I haven't got anything I can accurately measure the spar gaps between the spars on right now. The only wing I have open is out at the airport. There ARE different length compression tubes to make up for the thickness of the ply doublers and there are shims to keep the spars straight so make sure you put the right compression tubes in the right places.

Hank

Hank/ Drude Thank you both! Hanks reply raises another question... what is the front spar opening dimension? Also if If I understand you correctly ,Hank, is it both spar openings where the rib when mounted should have a gap on the top and bottom? One last double check.. what is the distance between the rear of the front spar and the front of the rear spar ? My understanding was the wing size of the DCO/65- L2 and the B series were the same.. sans the spar size.....

Thank you again you two!

[N96337]

Re: Need Measurement

As for the top and bottom gap it will vary depending on how straight your spars are. If your spars have a lot of curve (a lot of spar curve is NOT a lot of curve!) you could have NO gap on the end ribs on top and no gap on the bottom on a middle rib. The gap does not matter. What matters is that the tops of the RIBS are in a straight line. You move the ribs up or down to get the RIBS aligned, not the gap even.
Hank

I always try (if the fuselage is done and sitting right there) to match the butt rib to the top of the former on the fuselage. Then like Hank says, just keep them string line straight on the way out.
John

[Jim Herpst]

Re: Need Measurement

Robert

Perfect. Yes , You are correct. Thank you

The spar centres are 31 +/- 1/32. I'd suggest that is a more important dimension?

[Jim Herpst]

Re: Need Measurement

Thank you Hank !

[Jim Herpst]

Re: Need Measurement

Great Advice