11. Opposing-rotation aircraft propellers that share a common axis are known as contra-rotating propellers, rather than counter-rotating. 12. B�ttner also builds two-bladed carved wooden and two, three and four bladed plastic ultralight aircraft propellers . 13. His task at the committee, the forerunner of NASA, was to assess the vibration of aircraft propellers . 14. An aircraft propeller in the United Kingdom. 15. A military aircraft propeller and a plaque commemorating LtCol Bolt's accomplishments was erected at the airport in 2006. 16. Honda also aided the war effort by assisting other companies in automating the production of military aircraft propellers . 17. He specialized on problems connected with the design of aircraft propellers and of seaplane floats and flying-boat hulls. 18. Manufacturing companies, aircraft propellers , aero engine systems and terminology articles are also within the scope of the task force. 19. Most early aircraft propellers were carved by hand from solid or laminated wood, while metal construction later became popular. 20. Automotive gearboxes ran the opposite way to an aircraft propeller , and changing direction required modification of the camshaft lobes.
