Interaction Between the Spars of Semimonocoque Wings with Cutouts

The stresses in the two spars of a model of a wing having three rectangular cutouts were calculated by the PIBAL method, a modification of Southwell's method of systematic relaxations. The model was built and tested in the Polytechnic Institute of Brooklyn Aeronautical Laboratories and the deflections and strains measured were compared with calculated values. The agreement was found to be satisfactory.