1. This paper gives briefly the definition of fuselage with flexible rings and its method of analysis with particular attention to the problem of "Longeron Diffusian" and "Large Door Openings".

2. According to requirement of factory and experiment, U-shaped loading method was used to analyze the seat underframe and get the deflection and stress of test point on the front longeron.

3. One design trait shared by all Aeronca designs, except the Tandem Trainer and military L-3's, was a three longeron fuselage.

4. The test results from the standard circles with different radii and the industrious application of the stiffening plate of Santana's front longeron were presented.

5. This paper applies finite element approach to establishing multi-holed plate finite element mode and analyzing the stress of wing longeron web with several radius holes or openings.