Page 23 - Volume 12 Number 6

Type Certificate. Newell’s hard work had paid off. Later, he traveled to Wichita to personally observe all the static tests for the entire airframe, and particularly the wing. These tests were conducted at the Cessna factory and strictly supervised by a DOC inspector who carefully documented every step of the process.
The DOC’s static test of a wood wing was often a long and tedious process, often requiring days to complete. To evaluate the wood wing under various load conditions it was placed upside down on a special fixture designed to simulate various high angles of attack. The structure was divided into six sections along the wing’s 40-foot, two-inch span and three sections along the chord. That particular arrangement was deemed necessary so that loads could be applied to accurately simulate stresses encountered during flight. To simulate G-forces imposed on the structure, heavily-loaded sandbags were placed on the wing. As testing progressed, more weight was placed along the wing’s span. No failures occurred anywhere in the structure until weight equivalent to a load factor of 6.0 was applied. A four-foot section of the leading edge located about three feet from the root, began to yield but did not fail until a load factor of 6.5 was imposed.
To correct the problem, Newell instructed Cessna engineers to install both additional ribs and wider
An “A”-series forward fuselage was loaded with sandbags to a specific weight before undergoing drop tests
of the main landing gear from a height of 24 inches. The tests were witnessed by a govern- ment inspector who documented every detail. (ROBERT PICKETT COLLECTION/TEXTRON AVIATION)
KING AIR MAGAZINE • 21
The latest version featured a few modifications, including lengthening the fuselage to 25 feet from 23 feet, increasing total wing area by 50 square feet, redesigned wing ribs and four thickly-padded seats were installed in the fully upholstered cabin. A 200-horsepower Wright Whirlwind radial engine powered the ship.
The Cessna-Roos Aircraft Company’s monoplane was nearly ready for production. Newell had been working hard to complete the multi-faceted stress analysis of the monoplane’s airframe, followed by preparing and submitting a plethora of highly detailed documentation to the Bureau of Aeronautics for perusal by government aeronautical engineers. Earlier in the process Newell had notified Cessna that the original wing design was both overweight and overbuilt. As a result, he assured Clyde that production wings could be built lighter without sacrificing strength or safety factor.
When inspectors at the Bureau of Aeronautics reviewed Newell’s work, they advised the professor and Cessna that the company could proceed with deliveries to customers pending award of an Approved
JUNE 2018