Vintage Mechanic
THE
BY ROBERT G. LOCK
Aircraft covering, Part 2 In part 1 of this subject we explored the beginnings of aircraft fabric covering dating back to the WW1 days. It seems like it took a world war to rapidly advance the Aeroplane and such was WW1. Speeds and maneuverability increased dramatically and government sponsored research made advances in design, materials and processes. It was now time to apply the Aeroplane to civilian aviation. In the early 1920s, training and combat ships were occasionally seen flying about, particularly those machines used by the barnstormers. Curtiss Jenny and Standard J-1 were the favorite ships at the time, but covering materials remained the same as in WW1. There were no regulations or requirements for civilian aviators and their ships and, as we have seen, the covering cloth
was not protected from damaging ultra violet radiation from the sun. With government taking control of civil aviation in 1927, new regulations were written, including the covering materials for ATC’s ships. From Aeronautics Bulletin 7-A dated July 1, 1929, comes the following information on the properties of materials. “The materials used in aircraft structures must be of the best. Since it is impossible at the present time for the department to draft a complete set of specifications or to inspect and approve all materials to be used in aircraft, it is accepting those [materials], which conform to the specifications of the United States Army or Navy, the Society of Automotive Engineers, or other recognized standard. The use of materials of inferior quality or of those which experience has
ILLUSTRATION 1 32 SEPTEMBER 2012
shown to lack uniformity of quality or strength will be regarded as sufficient cause for withholding approval of a new design or for canceling approved type certificates or licenses already granted.� Therefore the specifications for aircraft cotton cloth and dope remained the same after the end of WW1. Aeronautics Bulletin 7-H was issued January 1, 1936 and contained data that could be applied for alterations and repairs to certificated aircraft. Illustration 1 is a direct copy from AB 7-H regarding aircraft fabric covering. NOTE: For more detailed information relative to fabric covering and stitching, reference should be made to Army and Navy specifications on this subject. When the Bureau of Air Commerce evolved into the CAA, Civil
