Gday y'all from down under, this fix is for the waco but could also apply to some other arf's that need the u/c and firewall strenghtened.
first a few abreviations....firewall-f1 to the back former in order..f1,f2,ect
main ply crutch pieces..7/8"x1/8" ply...crt
ok, now after finally getting mine $357 aussie...$264 us, I am not about to have it self destruct on landing...so after a lot of thought and reading all the theads...I didnt want to take all the sheeting and stringers from around the u/c area, or operate through the wing opening, I had this great idea...
cut a hole the same width as the crt in f1, 4.1/8" wide and 2.5/8" deep, this is 2.5" from the bottom-centre, and 2" from the top-center, mark f2 + f3 in line with the inside of crt..4.1/8" wide and cut down to the u/c plate on these then clean off glue ect from the u/c plate ready to take a piece of 1/4" 5 ply which goes from f1 across the top of the u/c plate to f4...approx 6.3/8 x 4.1/8"...fit it good up to the firewall f1 which is angled for right thrust and to f4...the wing le former...glue it onto the u/c ply plate,f1+f4 with good epoxy then reinforce front and rear with tri stock made from 1/2" square pine(cut diagonally) .
next cut 2 x 1/8" lite ply pieces to go vertically ontop of new 5 ply u/c plate to crt...these bits are approx 6.3/4"x 3.5/8"x 11.5" and taper up to the crt from f4 to f5 , glue to crt, f1 ,f2,f3 and new u/c plate... at the rear clamp to crt... reinforce with tri stock where needed.
a good way to mount the cowl is ...cut a ring from 1/4" 5 ply..7.3/16 " dia x 5/8" to fit the cowl...install the cowl carefully ..dont forget the f1 is angled for right thrust ...about 3/8" overlap...then with the ply ring against the f1 , glue it to the COWL only...then attatch to f1 with screws...use a long screwdriver through the front, much neater and stronger.
cut a new cover to mount the engine on out of 1/4" 5 ply 5.3/4" dia and either glue it on or bolt it useing blind nuts...u can inspect the inside/ fuel tank ect.
mine also had one cabane strut shorter ...made a newy, also I didnt like the wing joiners...made new ones out of solid oak.
I'm now working on a fiberglass u/c which wont bend!!. please read this over a few times... its not as bad as it seems.
sorry no digital camera...so if you've got any questions, post a thread or email me at ...
[email protected]
Ian White...Yankalilla...South Australia