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Basic Mechanics Question Paper

Basic Mechanics

Course:Bachelor Of Electrical And Electronics Engineering

Institution: Moi University question papers

Exam Year:2011

BASIC MECHANICS

1. A propeller driven aircraft of mass 12 t has a thrust of 12 kN when the power delivered to the propeller shaft is 2.2 MW at 500 km/h in steady, level flight. Find the propeller efficiency.

2. Find the power required at the engine brake shaft of an aircraft flying at a steady 60 m/s, if the thrust is 2.5 kN and the propeller efficiency 75 percent. What is the velocity of flow in the propeller slipstream relative to the aircraft at a point where the jet diameter is constant at 1.6 m?

3. An aircraft lands at 90 knots and the pitch of the propeller blades is adjusted to completely reverse the flow of air through the propeller and produce a braking thrust of 7 kN. The jetstream has a forward velocity of 85 m/s relative to the aircraft. Find the cross-sectional area of the jet.

4. An aeroplane is stationary on the runway under test and air is drawn into the propeller at 50 m/s. The slipstream has a velocity of 90 m/s and a jet diameter of 1.8 m well downstream. Find the thrust developed.

5. A propeller driven aircraft flies at 432 km/h in level flight. The engine supplies 800 kW to the propeller shaft and the conversion efficiency of the 2.8 m diameter propeller is 80 percent. Find the thrust and estimate the velocity of the air in the downstream well beyond the blades, relative to the craft.

6. An aircraft flies at 324 km/h in still air. The propeller diameter is 2.5 m and its propulsive efficiency is 78 percent. The velocity of the air across a section at the propeller is 98 m/s, relative to the aircraft. Estimate
a. The mass of air projected per second.
b. The velocity of the air at a point in the downstream, relative to the aircraft.
c. The power delivered to the propeller shaft.

7. An aeroplane flies in still air at 300 km/h. The velocity at a point in the slipstream in steady flow beyond the propeller is 95 m/s relative to the plane, and the propeller sweeps out an area of 7.06 square metres. Find the mass of air per second projected past the blades and the thrust. If the power delivered to the shaft is 950 kW, find the conversion efficiency of the propeller.

Basic Mechanics Question Paper

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