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 .
WW1 aircraft engines. Aviation at the Start of the First World War Lt. Kelly was the first person to die when piloting plane, on May 10, 1911. On the eve of the World War I, no country was prepared for using aircraft or had even admitted they would make an effective weapon of war.