grubbat
Well Known Member
I enjoyed reading the Kitplanes "Build it Better" article by Mr. Dye. When building my -9 several years ago, I would ponder different ways to build in extra margin here and there. Never once did I entertain the desire to exceed VNE true airspeed. I'm a firm believer that the designer owns the design and VNE was one area that I just didn't want to play with.
HOWEVER, building in some margin south of VNE has always been lurking not far from my thoughts. The 50ft/sec gust in the yellow zone at full gross is like a reoccurring nightmare, and it should be. That's why its a yellow zone. One wonders what will fail first when one finds themselves in they yellow zone in a deteriorating situation. They are not supposed to happen, but in reality, everyone will find themselves in a less than desirable situation at one point in their flying days and margin or lack of it will define whether you live to write about it or if the task is left up for the NTSB to do.
Data suggests oftentimes the tail will fail first when overstressed, and then the wing spar shortly thereafter. So, whats a builder to do to add in a little bit of margin for the tail? Well the answer is not so cut and dry, so to speak.
Airplane are a bunch of compromises. Designing a stronger tail usually means thicker skins, less overlaps using one piece skins, and more ribs which translate to more weight exactly where you don't want it, unless of course you are nose heavy anyway. Then you got to deal with the diminishing useful load due to the new and improved (and heavy)tail. A feller can't win.
Needless to say, the more I learn about these things, the more my appreciation grows for the engineers who spend countless hours designing and ensuring that the margins are acceptable given all the compromises. I've only been fixing planes for over three decades and not a day goes by that I learn something new from one of these designers.
To all you Engineers, designers, and smart folks, my hat is off to you. Thanks for all that you do. Mr Dye, thanks for another great article.
HOWEVER, building in some margin south of VNE has always been lurking not far from my thoughts. The 50ft/sec gust in the yellow zone at full gross is like a reoccurring nightmare, and it should be. That's why its a yellow zone. One wonders what will fail first when one finds themselves in they yellow zone in a deteriorating situation. They are not supposed to happen, but in reality, everyone will find themselves in a less than desirable situation at one point in their flying days and margin or lack of it will define whether you live to write about it or if the task is left up for the NTSB to do.
Data suggests oftentimes the tail will fail first when overstressed, and then the wing spar shortly thereafter. So, whats a builder to do to add in a little bit of margin for the tail? Well the answer is not so cut and dry, so to speak.
Airplane are a bunch of compromises. Designing a stronger tail usually means thicker skins, less overlaps using one piece skins, and more ribs which translate to more weight exactly where you don't want it, unless of course you are nose heavy anyway. Then you got to deal with the diminishing useful load due to the new and improved (and heavy)tail. A feller can't win.
Needless to say, the more I learn about these things, the more my appreciation grows for the engineers who spend countless hours designing and ensuring that the margins are acceptable given all the compromises. I've only been fixing planes for over three decades and not a day goes by that I learn something new from one of these designers.
To all you Engineers, designers, and smart folks, my hat is off to you. Thanks for all that you do. Mr Dye, thanks for another great article.