Aluminum spar wings

[bedsten]

Some years ago at the fly-in at Poplar Grove, somebody had plans for an aluminum spar wing, I believe with aluminum ribs as well, all for the CB-1 Does anybody know who this is? Has anybody built these wings? That is the next step for my project, and I would really like to investigate the metal wing. Have some experience with Cub & Champ rebuilds, and some local expertise with making metal ribs, so this sounds very good to me. Any help would be greatly appreciated!
Bruce Edsten

[mmcgrew]

I used Carlson Spars and water jet cut aluminum ribs. The ribs are one piece and are cut to the same Clark airfoil as used on the Hatz wood ribs. My wings are now covered and ready for the final paint. I am happy with the results and very comfortable with their strength. The pre fabric cover wing weighed around 50 pounds. I am not sure but I think this comes in close to the weight of the wood wing. Also I used the standard Hatz Classic attachment hardware shapes and sizes. I am going to try and post some pics.

Michael
N838MM

[mmcgrew]

Another wing pic

Michael N838MM

[mmcgrew]

Painted wing

Michael
N838MM

[mmcgrew]

READY FOR FINAL PAINT

Michael
N838MM

[stearmoth]

That's interesting also from an engineering point of view!
What is the weight of the uncovered top wing panel as shown on the pics?
Is there another +- load factor resulting when using aluminum instead of wood?
Hans & Sam, H.C. #78, Switzerland

[mmcgrew]

About 50 pounds. I am not sure on load? Looked at some test numbers on the wood to aluminum conversion for the Citb's and Decathalon. Aluminum showed better numbers under static loads. There are probably some numbers out there now for the Decathalon conversion as they have been flying for several years??.

Michael
N838MM

[ldmill]

Michael,
Bet you had fun going back through and adding in all the small lightening holes in the ribs after the fact... Also - are you going to try a center section out of aluminum? I'm just finishing up a Sonex/Waiex which is all aluminum and I'm quite comfortable with that, have no experience with wood outside of minor aesthetic repairs on my Pietenpol that I bought. Just curious.

Lorin Miller
Waiex N81YX (Jab3300)
Pietenpol N30PP (Cont A-75)

[mmcgrew]

As a mater of fact - My center section is done, Fuel tank installed and covered in fabric. I built the center section using the same spar components as the wings and two solid ribs at each end - seperated by compression tubes. I will try to insert a pic.

Thanks
Michael
N838MM

[mmcgrew]

PS - The lightening holes were cut when i cut the rib. I then made 2 part dies to press out the flanges.

Mike
N838MM