Abstract: A rate sensor, preferably comprised of a tuned gyro, has a generally cylindrical outer housing and an inner, large diameter rotary cylindrical support defining the gyro's rotary axis. The rate sensing apparatus is mounted in the volume between the outer housing and the rotary cylindrical support whereby the interior of the rotary cylindrical support defines a large diameter hollow for receiving and supporting apparatus, other than rate sensing components of the rate sensor. The rate sensor may be advantageously used with a homing device, the seeker apparatus of the device being mounted in said hollow. This produces a homing device with a high packing density and, as the rotary axis of the gyro gimbals and that of the seeker coincide, detrimental unbalance and unwanted increase in inertial movement is eliminated.