1 Discard any hammer with mushroomed or chipped face or with cracks in the claw or eye sections. 2  Wear safety glasses or goggles, or a face shield (with safety glasses or goggles).  Strike a hammer blow squarely with the striking face parallel to the surface being struck.
The first jet airplane was the Heinkel He 178 made in Germany in 1939, right before the outbreak of World War II .
For the near-Earth asteroid, see (35396) 1997 XF11. The Hughes XF-11 was a prototype military reconnaissance aircraft, designed and flown by Howard Hughes and built by Hughes Aircraft for the United States Army Air Forces. Although 100 F-11s were ordered in 1943, only two prototypes and a mockup were completed. During the first XF-11 flight in 1946, Howard Hughes crashed the aircraft in Beverly Hills, California. The production aircraft had been cancelled in May 1945, but the second prototype was completed and successfully flown in 1947.