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 .
World War II and the Jet Engine Allied Aircraft Without question, the British Gloster Meteor is the most famous Allied jet fighter, as it was the first to enter service in 1944.