The biggest advantage to the new sextant was the calibrated
azimuth ring which permitted direct readout of relative or true
bearings to the stars. Determining airplane true heading became a snap.
The biggest advantage to the new sextant was the calibrated
azimuth ring which permitted direct readout of relative or true
bearings to the stars. Determining airplane true heading became a snap.
There were some unusual uses for the instrument, however, that it's creators probably never anticipated. One widely practiced use was scanning the aircraft structure itself, especially in B-52 bombers. Setting the optical elevation angle to very low values often enabled the navigator or others to see the upper surfaces of the wings, the fuselage or other parts of the plane not visible to the pilots up front or to the tail gunner in the rear.
One B-52 crew concerned about an engine fine on #2, the second engine inboard from the port side (left) wingtip, used the sextant to determine the extent of smoke and flames threatening them. Through the sextant it was easy to watch the billowing smoke trail and the flames consuming the engine.
On another flight the sextant provided a good view of ice building up along the leading edge of the wings and up and down the vertical stabilizer of the tail. The pilot was kept informed of the situation as the layer of ice potentially altered wing performance.
The periscopic sextant also came to the aid of a contractor installing new equipment at Edwards AFB aboard JC-130 aircraft. A prototype heads-up display (HUD) was being installed to help pilots keep their eyes forward to watch for descending parachutes while still having a reliable indication of the true horizon despite clouds or darkness. Heading, rate-of-climb, attitude and airspeed were displayed on the HUD too. Calibrating the new instrument to ensure proper heading indications called for a procedure known as bore-sighting. The sextant came in handy as a way of determining bearings to distant targets and correlating HUD readouts to azimuth readings.
The writer still contends, despite doubting and scoffing remarks of other crewmembers, that he saw the Russian Sputnik satellite through the mildly telescopic optics of the periscopic sextant. That too was never an intended use for such a fine instrument.