Question for the experts. I'm in the process of reworking a few things in the plane and I thought while i'm at it i would replace the rear spar carry through bar with a widder one. The specs call for a 3/16 thick bar I have a 1/4 thick bar laying around the shop. I can get the 1/4 inch bar to fit in the saddle of the wing attach point, it is a little tight though. I think a couple of hits with a file and it will fit just right. Does anyone see anything wrong with the approach of fillling it down a touch to fit. And by the way its a 3-b wing.
Van's Air Force
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rear spar carry thru
- Thread starter dustman
- Start date
Hi Dusty,
I hate to comment on mods to critical structure - some things aren't that intuitive - but I have gotten good opinions from the engineering staff at Van's. As I have pointed out here before, no one at the factory but Van has ever built a -3, so don't approach them looking for an "official factory answer", but rather, use them as very experienced and educated sounding boards for your ideas. Email works well, as it will get passed to the right person.
My only thought on your mod is that if you do some filing, make sure that you really polish the part well to make darn sure there aren't any stress risers. (Obvious, I know - but less experienced folks will read these comments in the archives....)
Paul
I hate to comment on mods to critical structure - some things aren't that intuitive - but I have gotten good opinions from the engineering staff at Van's. As I have pointed out here before, no one at the factory but Van has ever built a -3, so don't approach them looking for an "official factory answer", but rather, use them as very experienced and educated sounding boards for your ideas. Email works well, as it will get passed to the right person.
My only thought on your mod is that if you do some filing, make sure that you really polish the part well to make darn sure there aren't any stress risers. (Obvious, I know - but less experienced folks will read these comments in the archives....)
Paul
nomocom
Well Known Member
thoughts on scrap
Dustman,
I applaud your efforts to reuse and recycle....and I agree with Paul. There sometimes are unintended consequences whether or not we recognize them. How will a thicker and stiffer part interact with the rest of the structure? Will it change vibration characteristics? Could there be a new harmonic resonance? Doubtful, but harmonics are just one area of possible unintended consequences. IMHO it isn't worth making changes to use up scrap.
Additionally, I haven't heard anyone faulting the 3B wing strength. Why depart from plans to make the airplane heavier when the part spec'ed in the plans was engineered and tested in the fleet? Those extra ounces do add up to be pounds. Now if I can just remember that as I enjoy lunch today
best
Dustman,
I applaud your efforts to reuse and recycle....and I agree with Paul. There sometimes are unintended consequences whether or not we recognize them. How will a thicker and stiffer part interact with the rest of the structure? Will it change vibration characteristics? Could there be a new harmonic resonance? Doubtful, but harmonics are just one area of possible unintended consequences. IMHO it isn't worth making changes to use up scrap.
Additionally, I haven't heard anyone faulting the 3B wing strength. Why depart from plans to make the airplane heavier when the part spec'ed in the plans was engineered and tested in the fleet? Those extra ounces do add up to be pounds. Now if I can just remember that as I enjoy lunch today
best
Actually, I should mention that many of us have modified the rear spar carrythrough with a WIDER piece of material (not thicker). That gives more margin for edge distance when setting incidence. And that was coordinated with the Engineering guys at Van's - no issues!
Paul
Paul
