CNC Ribs

[user 116312]

Hello All. I recently bought myself a set of Sonerai 1 plans. I have a CNC machine and a few hours in the seat using it. I can produce a fully hole matched part assembly for the wing. I would like to know if it is acceptable practice to produce ribs that look like this? - that is, they have 1/8 reliefs for the bends instead of being straightened using fluting pliers. I can produce the forming blocks such that they have a machined edge to the tabled bend radius for the material (in this case 0.020" 2024 T3, which is 0.060" for the inner radius). I have produced full hole matched assemblies for aircraft control surfaces before (but not for a full wing). It was very successful because no jigging was required and the holes do not need to be deburred. The surface cuts are all machined. The only assembly tool required is a rivet gun.

 

[Elviar]

Just my opinion, but I'd be concerned about cutting out the flutes. I think it would hurt the stiffness of the individual ribs and diminish the integrity of the structure overall. If you actually make a rib like this I expect you'll find it to be a somewhat flimsy component when compared with a fluted rib. But I'm sure you'll find plenty of other applications for your CNC machine! Good luck with your project!

 

[Wayne Byal]

Just my opinion, but I think you could add a backing strip with one edge with the same radii as the rib bend and put it tight to the rib and it would be just as stiff
when riveted to the skin. You could make a sample with just the inside strip riveted to the rib and see how stiff it compares to a standard rib just an idea

 

[user 116312]

Ok. So I am working on the idea of hole matching only the spar webs of the ribs and using the hole matching of the skins to the spars and using the skin machined holes to drill the rib webs later.
One rather confusing aspect of the plans concerns the Wing Rib Support angles (page 5 of the plans). These appear to be far less substantial than those shown on the pictures on the Wing Construction Manual (that I assume are of the Sonerai II). Was it consciously decided that the Sonerai II needed them while the Sonerai I did not? I could easily incorporate the Sonerai II ammendments, but have wiser minds than mine already covered this? I would like to see what the specifications of those supports are, but am I right to assume that I am up for another $250.00US to see them?

 

[soneraifred]

The wing rib and spar reinforcements that you see in the Wing Construction Manual apply to the Sonerai II. The mods were never required for the Sonerai I by its designer, John Monnett. They were only required by the Formula Vee racing association if you wanted to race. If you haven’t already done so, I’d recommend reading the “Sonerai Wings” post in the Sonerai II Airframe Discussion Board. Also, if would like to see how the wing can be modified, see the .pdf file in the “Sonerai II A-Wing Modification Drawings” post in the Sonerai Files, Documentation, & Service Manuals board.
Fred

 

[user 116312]

Thank you for your reply and the information Fred. I will certainly avail myself of the resources.