FAIREY SWORDFISH RADIO ALTITUDE CONTROLLER

***PLEASE NOTE THERE IS ONLY ONE ALTITUDE CONTROLLER AVAILABLE***

As part of the US Lend Lease program, many British aircraft components and instrumentation had been developed and manufactured in the US togther with a number of radio and radar systems such as the US AN/APN-1 radio altimeter.

The General Electric Radio Altitude Indicator, ID-236/APA-61 was a component of Radar Bombing Navigational Computer AN/APA-61 and was used to measure and indicate to the pilot the altitude over the terrain during flight.

This was particularly critical for British coastal command fighter/bombers such as the carrier-launched Fairey Swordfish and Bristol Beaufighter and USN aircraft such as the TBF Avenger torpedo bomber and the SB2C Helldiver dive bomber.

The AN/APN-1 was the US Navy's primary airborne frequency modulated, radio altimeter which was designed to emit a downward signal from the aircraft's transmitter antenna.

As the terrain changed in hight and composition with the rise and fall of the aircraft's flight, a 'bounced' return signal would be received by a separate receiver antenna. The difference in signal frequency and time interval from send and receive gave a highly accurate height reading.

The timing and correct height of torpedo or dive bomb release was crucial to ensure the weapons had enough time to self arm and hit their targets.

The system provided a dual range indicator of 0-400 feet and 400-4000 feet; having an accuracy within plus or minus 6 feet on the 400-foot range and within plus or minus 60 feet on the 4000-foot range.

Both glass and casing are in excellent condition and the fully functioning lower left knob switches on the indicator, with the top right knob switching the measured range between 0-400 ft to 400-4000 ft.

This Fairey Swordfish Instrument comes complete with detailed Scale Model, Mango Wood Stand & Plaque plus Printed Fact Sheet featuring photo of instrument in the aircraft cockpit.

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