WIng Spar

[geraldmorrissey]

I'm sure this has come up before but I have not seen it and was unsuccessful searching. Why couldn't all the detail parts of the spars, capstrips, spacer bars, attach fittings and splice plates, be incorporated into two parts. Part one could contain the root spacer, capstrips, spacer bars and splice plate. The second detail part would index and overlay the first part. It would contain the root attach fitting, capstrips, spacer bars to bring the thickness to .25 as required, the diagonal spacer under the strut attach fitting. Yes the .25 spacer bars would be two piece but the three most inboard spacer bars are already two piece (on the Patrol). Expense, a lot more. Waterjet cutting a 4 x 12 sheet would only yield 5 parts. But after building Patrol main spars I sure as hell would have bought them. It would bring the parts count down to 4 detail parts or so plus the webs. It would require serious stress analysis at the spacer bars but very doable. You could dirlll a few index holes and cleco everything in place with all the rivet holes predrilled by the waterjet. Plus you could add corner radaii and all intersections (spacer bar to capstrip for example) to add strength with little weight gain. Plus all the fay surfaces that you fuss over to get tight fitting parts goes away. I see it as a much improved structure with the only issue being the spacer bars. My spars are well along so I'll never get to try but it's food for thought. If it doesn't work it would make a divine rose trullace.
Gerry
Patrol #30 Wings

[X'N]

I thought about doing the same exact thing but $$$ came into the picture. The cheapest quote I got for waterjet cutting a single 4x12 sheet was $800 on top of the sheet cost. The other issue I've seen with waterjet is angled cuts on the material if they don't have the correct pressure and feed rate and small holes can come out oblonged. If I had the shop space I'd really consider building a cnc router big enough to do the job while it would take more machine time you would end up with a better product in the end.

The other problem is the cap strips near the spar would end up being 1.375" longer that 12' Not sure if that could be shortened.

[X'N]

Take that back it would only be the rear inner cap strip part that would be over 12' here's a poor image to give an idea what they would look like.
Looks like you would use one and a half sheets. At $631 (ACS price per sheet) that's pretty close to a grand just in material costs.

[geraldmorrissey]

I think it's a process that would best be done in volume If you were buying AL a hundred sheets at a time and cutting 10 details at a time it might make sense. I think I counted 46 details in a Patrol main spar. A 80-90% parts reduction might be possible.
Cheers
Gerry
Patrol #30 wings

[Jflyer]

You know? Brilliant idea. I'm still building my 6' X 13' CNC router. Still a month or two away from cutting chips. When finished, I'll give it a shot and send a sample to Bob and see what he thinks about it

[X'N]

May as well go 14' so you can do the rear spars on the 4-place

[Jflyer]

Crowded enough already in the shop. My intention for the 13' is to layout 12' sheets of aircraft aluminum. Is it available longer? I'm guessing with this idea, there will still be a couple of pieces that need splicing

[X'N]

I have not looked for sheet stock of 1/8 6061 it may not be available in 14' lengths maybe only available in bar stock.

[Jflyer]

Are t the cap strips 2024 T3/T4? Or is there a variance with some?

[X'N]

On the patrol they (cap strips) are all 2024 t3-4. The 4 Place cap strips are 2024 t3/4 for the main and 6061 for the rear spar cap strips.

[Jflyer]

Whicks has it in 4X8 sheets for $265. 6061 T6, Bare