Original spars were laminated; later ones were one piece. I am unaware of a Cub wood spar failing in flight. The Scout had maybe four in-flight failures after hitting things, and now the entire fleet goes through a rather expensive annual spar inspection. That tells me the FAA is unaware of Cub spar failures.
But I agree - go aluminum. Stronger, and way better at recover time. Readily available. Don't re-invent stuff just to make it heavier.
Yeah, that's what I was thinking about.The boxed wood spar is really stout. First used by Anthony Fokker in 1917 in the D8, so strong it was strutless. Stampe also used them in there aerobatic biplanes.
View attachment 51308
Glenn
A D shaped box spar is a) at least as light as the stock cub arrangement, and potentially lighter, and would b) substantially strengthen the wing at the point where one would put slots and slats. D shaped box spars can be made from aluminum, plywood or carbon fiber, and are in other Cub-like aircraft.I thought I was posting in the "Experimental Cub" section. My mistake. This is obviously the "Cubs cannot be improved upon" section.Thanks for the input.
It is sad that you have formed this opinion. While there may be a few negative comments, most should be taken with a grain of salt. This group is one of the best with more accumulated knowledge freely given than anyone could imagine. I have minimally connected with some other sites where the collective civility is minimal at best. You've only been here a few days, sit back and observe. Give us more time, you will find this to be the best group of people in the industry....I think some of you are pre-loaded to just blow up at posters when triggered. In my few days on this forum, I've seen more testiness and outright hostility than in any other place. Life is too short to hang out in a place full of negative people. Good day.
The stock cub spar and leading edge do form a "kinda, sorta" D spar. Yes, I know that. I've built three sets of aluminum wings and one set of wood wings for Piper aircraft as an A&P.The rest of you, with some exceptions, are reading way too much into my question. I simply want to know what has been done before; and if possible if there is something interesting to imitate, if I decide to build. I have been out of the civil aviation/small plane world for about 12 years, and have noticed a lot of Cub-like airplanes that weren't here when I left. I think some of you are pre-loaded to just blow up at posters when triggered. In my few days on this forum, I've seen more testiness and outright hostility than in any other place. Life is too short to hang out in a place full of negative people. Good day.