1801-1900

1801. If the airflow is constant and you decrease the diameter of the jet nozzle (Level 1)

• a) The outlet velocity does not change
• b) The outlet velocity decrease
• c) The outlet velocity increase

1802. The thrust is generated by (Level 1)

• a) Pushing against the atmosphere
• b) Acceleration of airflow
• c) Acceleration of airflow and pushing against the atmosphere

1803. With increasing altitudes (Level 1)

• a) The ambient pressure decreases and the temperature decreases
• b) The ambient pressure decreases and the temperature increases
• c) The ambient pressure increases and the temperature decreases

1804. There was no engine compressor before 1937 due to (Level 2)

• a) There was no one can invent it
• b) There was no material that was heat-resistant enough for continuous combustion.
• c) The engine without compressor has better performance

1805. Turboprop engines do not use on large A/C due to (Level 2)

• a) This engine is very loud
• b) This engine is not efficient
• c) It's hard to manage the rotation speed of propeller

1806. On modern turbofan engines the bypass ratio is between 4:1 and 9:1, that means the fan can produce more than 80% to …% of the total thrust (Level 2)

• a) 0.9
• b) 0.7
• c) 0.95

1807. If the velocity of the air at the engine inlet increases, thrust force would be (Level 2)

• a) Stay the same
• b) Increased
• c) Decreased

1808. The higher the altitude, the…of the thrust a jet engine can produce (Level 2)

• a) More
• b) Less
• c) Equal

1809. The reduction gear is used on turboprop engine for what purpose? (Level 2)

• a) Reduce speed of propeller
• b) Increase speed of propeller
• c) Maintain speed of propeller

1810. The fans of turbofan engine are always driven by (Level 2)

• a) A turbine via two drive shafts
• b) A compressor via a drive shaft
• c) A turbine via a drive shaft