I don’t know why every manufacturer doesn’t extend the wing spars under the cockpit. It is not as if the PA28 needs to have quickly removable wings.
This is the Socata TB approach
I don’t know if the bolts are precision bolts but most likely not.
I don’t know why every manufacturer doesn’t extend the wing spars under the cockpit. It is not as if the PA28 needs to have quickly removable wings.
Or even have a one piece main spar.
With wooden wings you have to go underneath because wood has little strength for “butt” joints.
Peter wrote:
This is the Socata TB approach
Similar, in principle at least, with most RVs. Only Vans do it 10 times more elegant using 1/4 the number of bolts It also depends on how the spar is attached to the fuselage though.
Peter wrote:
I don’t know why every manufacturer doesn’t extend the wing spars under the cockpit. It is not as if the PA28 needs to have quickly removable wings.
Even then – e. g. the Europa or the RV 12 have quickly removable wings – one can extend the spars to the opposite side of the fuselage.
Some gliders have spars that go to the opposite side of the fuselage, and they are designed for quick rigging and de-rigging.
I think most new planes have some form of quick detachable wings today. New planes = microlights/LSA It doesn’t really complicate anything, it is in fact easier to calculate and do it right, when doing it from the ground with purposely designed spars. Gliders have had it almost for ever, and dozens of excellent working solutions exist. At HomeBuildAirplanes there are posters who seemingly live and breath spars Wing spars are really interesting engineering wise when diving into it. The Spitfire has an unusual but cool spar design for instance.
Oh well, I have the 7 yearly Piper “tanks out” inspection due no later than early 2019. I was going to combine this with a re-spray earmarked for the end of this year.
So now I’ve extended the work to have the wings removed, NDT the bolt holes, re-spray the wing roots, repaint the carry through box and the two steel fixings aft and forward can be stripped back, inspected, zinc primed and repainted. It makes the re-spray a better job and sets the Aircraft up for the next 30 years by which time everything will be electric! It’s not going to put me off flying in the meantime though.
The straight through spar on the Mooney used to be a major selling point:
Spars don’t last forever. Talked to some guys flying an old AA-5 this afternoon. The wings are easily removable. The structure was more like tubes going into larger tubes, if I understood them correct. The larger tubes were intrinsic parts of center fuselage. The problem was that this center part has 11500 h max, and fixing it is not really an option, way too expensive, and there are no parts to be found either.
All the RVs can be bought with anodized spars. Excellent against corrosion, but anodized parts are prone fatigue cracks. If I remember correct, the anodized spars have max 10000 h total time. The non-anodized spars have no such limit.
10k hours are 100 years flying 100 h per year, so it doesn’t really matter all that much on average, but still.