The proplem of theoritical determination of stresses and strains in a thick walled viscoelastic cylinder reinforced by steel shell and subjected to interinal pressure and external pressure (arising due to the elastic shell) had been treated by the authors [1,2].To check the theoritically obtained solution of the discussed problem experimental investigations are carried out. In this experimental work the elastic shell is made of steel and the viscoelastic cylinder is made polyvinyle-chloride (PVC). The dimensions of the steel shell and PVC thick cylinder are estimated with reference to the actual rockets working with soild propellant fuel. The experimental tests are performed under constant pressure which corresponds to the steady
conditions of the soild fuel rocket work. These tests are worked out on specimens of different diameters of steel shells and PVC cylinders with an apparatus designed specially for this purpose. The theoritical solution of the considered problem incase of PVC is obtained using the same analysis and computer program used before [2] . The only difference is that the
mechanical constants El, E2, n1 and n2 of the used before material is replaced by that of the PVC . To going through these theoritical investigations, the mechanical properties of the PVC must be measured this was carried out in another work [3].