Question 1:

a. Describe Pascal's law at the basis of the operating principle of a hydraulic system. In addition, describe the objective of a hydraulic system and provide some examples of components actuated by hydraulic power.

b. Discuss the main differences between hydraulic and pneumatic systems.

Question 2:

a. Considering the characteristics and needs of an aircraft in flight, discuss which are the main requirements associated with the fuel system, and describe the main function of the two types of fuel pumps in an aircraft.

b. Discuss the main advantages and disadvantages of storing the fuel in the wings.

Question 3:

a. With the help of appropriate sketches, describe the operation principle of a distance measuring equipment (DME).

b. Describe the "jitter" strategy adopted to overcome the problem of an aircraft receiving the DME replies sent to all the other aircrafts.

Question 4:
A commercial aircraft is flying at an altitude of 11000 m. The total temperature of the flow is 244 K. By considering a constant ratio of specific heats for air equal to 1.4, and assuming homogeneous distribution of the temperature over the fuselage surface, determine:
a) the flight Mach number;
b) the fuselage skin temperature for the case of laminar flow;
c) the fuselage skin temperature for the case of turbulent flow.
d) With the help of appropriate figures/sketches briefly describe the operation principle of the environmental control system, and discuss the results obtained above in points b) and c) in terms of the requirements for the environmental control system [max. 150 words].