Problems with CG calculations & folded wing stays
Posted: Fri Mar 22, 2024 12:24 pm
Preliminary CG calculations using three Walmart bathroom spring scales produced crazy results. 1st try put main gear weights at 120 and 122 pounds. I had expected readings on the high side (before removing "not essential for flight" items like cushions, cowling, prop extenders, iPad Air, fuel gauge and sender, and replacing the heavy duty starter battery, etc ... I calculated roughly 11 points). However, the tail-wheel (long moment arm) came in at F) POUNDS! Chris said that the highest wail-wheel weight he' seen or had reported was 40#.
Has to be the scales. I had somewhat calibrated them with my doctor's office weight. so I swapped the tail-wheel scale with the port gear scale and once again the port gear showed 120# and the tail-whee reading was now 34#. Still this puts the CG 5+" aft of the desired range I'm convinced that the scales are wildly inaccurate and had sent an email to the local EAA chapter about loaned scales.
While waiting to hear from the local members, I've returned to working on "stay mounts" for the folded wing using the 3/16" bushing welded to the frame at the base of the vertical stabilizer and the 5/16" tie-down locations on the aft spar lift strut fittings. I have threaded both ends of two 3/16" steel rods and added clevis forks fo make the rigid connections.
That's a 7/16" od by 5/16" id aluminum bushing spacer on the bolt to provide clearance to access the clevis fork pin. (These fittings are also "not essential for flight" weight items.)
The plan is to load the bird on my converted boat trailer and fabricate a fitting that will attach to the tail-wheel rod/spring and to use my Harbor Freight D-rings attached to the flat plywood bed allowing the use of cargo straps to secure the main gear fore-aft and port-starboard.
More to come.
Has to be the scales. I had somewhat calibrated them with my doctor's office weight. so I swapped the tail-wheel scale with the port gear scale and once again the port gear showed 120# and the tail-whee reading was now 34#. Still this puts the CG 5+" aft of the desired range I'm convinced that the scales are wildly inaccurate and had sent an email to the local EAA chapter about loaned scales.
While waiting to hear from the local members, I've returned to working on "stay mounts" for the folded wing using the 3/16" bushing welded to the frame at the base of the vertical stabilizer and the 5/16" tie-down locations on the aft spar lift strut fittings. I have threaded both ends of two 3/16" steel rods and added clevis forks fo make the rigid connections.
That's a 7/16" od by 5/16" id aluminum bushing spacer on the bolt to provide clearance to access the clevis fork pin. (These fittings are also "not essential for flight" weight items.)
The plan is to load the bird on my converted boat trailer and fabricate a fitting that will attach to the tail-wheel rod/spring and to use my Harbor Freight D-rings attached to the flat plywood bed allowing the use of cargo straps to secure the main gear fore-aft and port-starboard.
More to come.