Page 310 - SSB Interview: The Complete Guide, Second Edition

forces the stern upward; therefore, the submarine is angled downward.
To keep level at any set depth, the submarine maintains a balance of air

and water in the trim tanks so that its overall density is equal to the

surrounding water (neutral buoyancy). When the submarine reaches its
cruising depth, the hydroplanes are levelled so that the submarine travels

level through water. Water is also forced between the bow and stern trim
tanks to keep the sub-level.

79. The submarine can steer in the water by using the tail rudder to turn

starboard (right) or port (left) and the hydroplanes to control the fore-aft

angle of the submarine. In addition, some submarines are equipped with
a retractable secondary propulsion motor that can swivel 360 degrees.

When the submarine surfaces, compressed air flows from the air flasks

into the ballast tanks and the water is forced out of the submarine until
its overall density is less than the surrounding water (positive buoyancy)

and the submarine rises. The hydroplanes are angled so that water

moves up over the stern, which forces the stern downward; therefore, the
submarine is angled upward. In an emergency, the ballast tanks can be

filled quickly with high-pressure air to take the submarine to the surface
very rapidly.

INDIAN AIR FORCE

Formation

80. The Indian Air Force (IAF) was established in British India as an
auxiliary air force of the Royal Air Force with the enactment of the

Indian Air Force Act 1932 on 8 October that year and adopted the Royal

Air Force uniforms, badges, brevets and insignia. On 1 April 1933, the
IAF commissioned its first squadron, No.1 Squadron, with four

Westland Wapiti biplanes and five Indian pilots. The Indian pilots were
led by Flight Lieutenant (later Air Vice Marshal) Cecil Bouchier. Until