51 J-3 Cub
Rework Fuselage Unsupported Lower Longerons
In my previous Report No. 50, I said. "I am a little concerned about the covering pulling in the soft lower longerons when I start doping. However, I can not do anything about it now." The two sections that concerned me are shown below. The alcohol shrunk tissue covering without dope is already starting to bow in the longerons as you can see below. I knew without a doubt this situation was only going to get worse, maybe even to the point of being unsightly! So I decided to go back and try to add some longeron structural supports inside the tissue covering, which is always a bit tricky.
However, I managed to add braces to the bottom
longerons in the two unsupported bays as shown below.
The picture below shows the four longeron braces
neatly integrated into the side structure. Each brace was carefully bonded
in place with a tiny bit of CA so as not to get it on the inside tissue. I
also added the two cross member braces to prevent the two bottom longerons
from pulling in across the bottom when it is covered. Hopefully, this will
keep the longeron warping to a minimum. Seems as though I am constantly
having to going back and rework areas of concern that I was not perceptive
enough to anticipate..............................Tandy
