Making Aluminum ribs

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Little Scrapper

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what do we know or what have we learned about making aluminum ribs for wood spars? That’s a big question.

If I were to make aluminum ribs instead of wood what can you tell me? Angle size and thickness? How to shrink / stretch the extrusion for consistency from rib to rib?

How are these nailed to spars?

What are some thoughts on the supports that connect the two cap strips together?

This should be a good discussion.
 

Little Scrapper

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My Champ has wood spars and aluminum ribs with PK screws as opposed to rib stitching. Mr Bill Pancake built it (along with others) and would offer you a wealth of knowledge on the subject.
Bill Pancake? Is he a member here? For experimental category I know there’s been a few guys who have done it. Trying to figure out what they used and how they got consistent and matching curves.
 

Pops

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My Champ has wood spars and aluminum ribs with PK screws as opposed to rib stitching. Mr Bill Pancake built it (along with others) and would offer you a wealth of knowledge on the subject.
If you have a Champ built by Bill Pancake, its first class in every way. Bill has been to our field several times, lives across the state from me.
 

Kyle Boatright

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On the Champ, the ribs are attached with nails. The fabric is attached via PK screws.

Just clarifying.

The Champs' ribs are press formed aluminum, not built up trusses like Cub ribs.
 

TFF

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I think duplicating Cub rib that Wag Aero would be the least mess. I would add the aluminum spars from Carson.
 

cluttonfred

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It's interesting to compare Mike's rib above with Marc's Fisher Skylite ribs in this log thread: Raceair Skylite Build and sub-kit developments

They are clearly different in terms of spar locations and attachment methods but I wonder what other approaches are out there? Maybe use a wooden form to bend aluminum tube for the curved upper capstrip, then a small jig to press flat spots in the capstrips and vertical ends to make a little riveted truss?
 

Victor Bravo

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I've mentioned this before, but any discussion of aluminum truss ribs for homebuilts should at least include a mention of the Kolb system. Not necessarily the tube spars, but the tube/gusset rib truss. Really really simple, made with minimal fabrication.
 

Aerowerx

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.... Maybe use a wooden form to bend aluminum tube for the curved upper capstrip, then a small jig to press flat spots in the capstrips and vertical ends to make a little riveted truss?
Like in the AffordaPlane plans, as an alternative to the foam ribs.
 

cluttonfred

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Got any good pics or drawings of the Kolb system, VB?

I've mentioned this before, but any discussion of aluminum truss ribs for homebuilts should at least include a mention of the Kolb system. Not necessarily the tube spars, but the tube/gusset rib truss. Really really simple, made with minimal fabrication.
How about a pic, Aerowerx, even just a phone snap, for those that don’t have AffordaPlane plans?

Like in the AffordaPlane plans, as an alternative to the foam ribs.
Possibly, robertl, but not necessarily. There are lots of aircraft over the years that have used mixed materials and fabrication techniques. As long as there isn’t a steep learning curve or lots of tooling involved with changing techniques, I don’t see any problem with mixing and matching.

Wouldn't it be easier to build an aluminum spar to go with the aluminum ribs?
Boy
 

addicted2climbing

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It's interesting to compare Mike's rib above with Marc's Fisher Skylite ribs in this log thread: Raceair Skylite Build and sub-kit developments

They are clearly different in terms of spar locations and attachment methods but I wonder what other approaches are out there? Maybe use a wooden form to bend aluminum tube for the curved upper capstrip, then a small jig to press flat spots in the capstrips and vertical ends to make a little riveted truss?
The Skylite ribs use crumping pliers to form the curve but as the curve forms you also get a bit of a twist so the second flange is crimped to get the twist out as you go. It works well, and with the jig you can be pretty consistant but i would like to try a press to get the shape or a special designed slip roll with a geared dies that I feed in with a few cranks and get the shape. Its on the list yo try but but busy with another project right now.
Due to the fact that the ladder truss is built first the upper surface of the rib is not riveted in the Jig. Its cleco’d so that itcan be removed and the lower half of the rib is fit in place And attached to the wing frame then the upper drops in from above and riveted. This is so there is no interferance with the cross bracing as you instal the ribs.
 

Aerowerx

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How about a pic, Aerowerx, even just a phone snap, for those that don’t have AffordaPlane plans?
This is what is in the AP plans, for building aluminum ribs. Although I think you could get a better airfoil shape by using a more elaborate bending jig. They also show the plastic inserts, which appear to be no longer available from AS. You might be able to flatten the ends of the tubes and rivet directly to the spars.
AP rib3.JPG
shape AP rib2.JPG
AP rib1.JPG
 
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