Proving The Design

Proving The Design...Testing the SR3500

Recently the SR3500 wing and stabilizer under went load testing for the new gross weight of 3,500 and the 360 h.p. radial engine. Both passed their respective tests and Murphy Aircraft is currently making the new parts. The following addresses the three load tests performed on the wing:

An integral part of the design process at Murphy Aircraft is the proving stage stress testing the wing and various components to prove they meet required load limits. Most recently this was done on the new SR3500 airframe to increase the strength to handle an additional 500 pounds and 100 more horsepower.

Murphy Aircraft is very proud of the rigorous testing that they put their product through. While all components are vitally important, the wing is of primary importance and goes through nine condition checks (paper analysis) of flight loads and three worst case scenarios are tested at our factory. The three tests performed for the SR3500 were an aileron roll case at V dive, a V dive test and a high angle of attack test.

High angle of attack test with 8,400 lbs loaded onto the wing simulating 3.8 g's at gross weight (3,500#)

Aileron roll test with 6,100 lbs loaded on the wing. This test simulates full aileron deflection (twist) coming out of a 224 mph dive. The ailerons are loaded with 400 lbs.

The aileron roll case simulates the wing at 3,500 lbs. in a 224 mph dive (V_D) when the pilot introduces a 3.8 positive G-load on the wing while simultaneously entering full aileron deflection. This test tries to both break the wing under a load and twist it off at the same time. 6,100 lbs. was loaded onto the wing with the ailerons carrying 400 lbs. (the twisting effect).

The V dive (V_D) test simulates a wing at 3,500 lbs. in a 224 mph dive (V_D) at which point the pilot introduces a 3.8 positive G-load. This test had the wing loaded with 8,400 lbs.

The high angle of attack test simulates turbulent air penetration at gross weight at the maneuvering speed (V_A) of 133 mph. At this point the pilot introduces a 3.8 positive G-load onto the airframe. This test has the wing loaded with 8,400 lbs and mounted to the stall angle of attack. One difference with this test and the V dive test is the loads that are put on the attach points.

All the tests performed assume the aircraft at gross weight, at maximum allowable G-load and include a 50% reserve factor. An independent aeronautical engineer conducts all these tests.