I hope that was an eye-catching title for this post!
This is not a building question, but I'm hoping that the engineers or at any rate the more aeronautically educated, can educate me about wings spars and spar bolts on the RV-8. I'm interested to understand something of the maths/physics of the calculations involved in the fuselage/wing joint. I've been staring at the little stub spar on my wings for awhile now. I was looking at a Spitfire rebuild a few months ago and it too has little stub spars for the wings.
As I understand it, the load on the bolts is entirely in shear - the close tolerance of the bolts and the spar/sparbox assembly ensures that the forces should be shear only with no bending possible and obviously no tension. Then its just a matter of calculating the levers involved - pivot is say the fuselage edge or the most outboard bolt, the remaining bolts are say 3 inches from the pivot, lift force is weight of the aircraft at 6g times the distance to the centre of pressure of the wing (easy to calculate with an untapered wing) and there will no doubt be an additional safety factor. Is that the gist of it? I guess there are similar calculations to make about the main spar and the stub and spar box assemblies using information about their stiffness/resistance to deformity?
I'll be interested and grateful for any information as part of my general aviation education.
Chris
RV8, empennage and wings complete, working on engine cowling
This is not a building question, but I'm hoping that the engineers or at any rate the more aeronautically educated, can educate me about wings spars and spar bolts on the RV-8. I'm interested to understand something of the maths/physics of the calculations involved in the fuselage/wing joint. I've been staring at the little stub spar on my wings for awhile now. I was looking at a Spitfire rebuild a few months ago and it too has little stub spars for the wings.
As I understand it, the load on the bolts is entirely in shear - the close tolerance of the bolts and the spar/sparbox assembly ensures that the forces should be shear only with no bending possible and obviously no tension. Then its just a matter of calculating the levers involved - pivot is say the fuselage edge or the most outboard bolt, the remaining bolts are say 3 inches from the pivot, lift force is weight of the aircraft at 6g times the distance to the centre of pressure of the wing (easy to calculate with an untapered wing) and there will no doubt be an additional safety factor. Is that the gist of it? I guess there are similar calculations to make about the main spar and the stub and spar box assemblies using information about their stiffness/resistance to deformity?
I'll be interested and grateful for any information as part of my general aviation education.
Chris
RV8, empennage and wings complete, working on engine cowling