Figure 1-9. AADS Angular Freedom.

TM 9-1270-219-13&P

c. The pressure head is equipped with a heating

errors on either pressure. These pressures are conveyed via

e l e m e n t which provides anti-icing capability.

the shafts of the gimbal and helicopter plumbing to the

EPU.

b . Movement of the gimbal arrangement also causes

d . An Air Temperature Sensor (ATS) is attached to

two angular resolvers to generate electrical signals

the body of the AADS, at an angle such that it does not

r e p r e s e n t i n g the movement of the head in pitch and yaw

interfere with the airflow over the pressure head or pick

axes

relation

the

helicopter.

These

signals

are

up heated air from the flow around the head.

transmitted to the EPU where, together with the pressure

signals, they are used to compute airspeed and direction.

T h e gimbal arrangement permits total angular freedom in

A A D S p h y s i c a l D e s c r i p t i o n . The AADS consists

p i t c h and 120 in yaw (fig. 1-9); this allows the head to

of six main assemblies: a head assembly, a tail assembly, a

sense accurately the local impact and static pressures over

neck assembly, a body and plug assembly, a cover and

an airspeed range of up to 223 knots forward, 32 knots

dowel

assembly

and

plate

and

connector

assembly.

sidewards and 32 knots aft.

Figure 1-9. AADS Angular Freedom.

1-10