Hi everyone,
Thanks to the great advice I've received and references referred, I've got copies of Bruhn and Peery at my finger tips. Today I read through "Chapter 10: External Loads on the Airplane" of Peery, as well as "Chapter D2: The Loads on the Body" of Bruhn. I'm getting a good feeling for how we determine loads on the fuselage.
In addition, I watched the six-video set of "How To Solve a Truss" that someone else suggested:
https://www.youtube.com/watch?v=p9CMc3FaYVs
So between those two, I'm feeling pretty good about getting a running start at the tube fuselage of an existing proven design, doing the geometries on it, and then bouncing those against the chosen materials to see how someone who has been designing airplanes for a long time chooses the tubing sizes he does for his design.
Bruhn has really nice examples of doing a weight analysis, and picking out the heaviest parts and their locations to determine forces on the fuse. But I'm still trying to wrap my head around the typical load points and how/why they're selected. So, in no particular order:
Many thanks for your insight!
~Chris
Thanks to the great advice I've received and references referred, I've got copies of Bruhn and Peery at my finger tips. Today I read through "Chapter 10: External Loads on the Airplane" of Peery, as well as "Chapter D2: The Loads on the Body" of Bruhn. I'm getting a good feeling for how we determine loads on the fuselage.
In addition, I watched the six-video set of "How To Solve a Truss" that someone else suggested:
https://www.youtube.com/watch?v=p9CMc3FaYVs
So between those two, I'm feeling pretty good about getting a running start at the tube fuselage of an existing proven design, doing the geometries on it, and then bouncing those against the chosen materials to see how someone who has been designing airplanes for a long time chooses the tubing sizes he does for his design.
Bruhn has really nice examples of doing a weight analysis, and picking out the heaviest parts and their locations to determine forces on the fuse. But I'm still trying to wrap my head around the typical load points and how/why they're selected. So, in no particular order:
- For a typical "GA" plane in the 2500-pound range, are the greatest forces typically experienced in flight, or stationary on the ground? I get this feeling of neutrality while the plane is flying, but I know that's not right. The weight of the structure is being supported by the wings and tail (although opposite forces). So the weight minus wings being suspended, versus propped up by the gear on the ground. So I see that as a "pressure point" to be measured.
- On the ground, I presume we're measuring from the gear attachment and tailwheel as the points of reference? Of course there are weights in the middle to deal with, as Bruhn points out. Things like anticipated passenger weights, cargo, etc.
- I read that we must plan for the worst-case scenario: the less-then-perfect landing. Can't remember if that was Peery or Bruhn, but either way it has to be done. I know some of my landings haven't been the best, but I don't know that I've made any 4.5g landings, either. The 4.5g typical limit is for Utility Category planes, if memory serves. But I believe this is for in-flight structural integrity. Do we need to account for 4.5g landings, or are even the hardest landings less than that? I've never felt like I weighed 800 pounds during a landing, so this may not be typical.
Many thanks for your insight!
~Chris
