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 .
The concept of a jet turbine-probelled aircraft was first documented, independently, by Frank Whittle in the UK in 1928 and by Hans von Ohain in Germany in 1936. Whittle paten â¦ ted his design in the UK in 1930. The first jet aircraft to actually fly was built in Germany in 1939.