The AN/APN-1 was the US Navy's primary airborne frequency modulated, radar 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 pilot first set the Radio Altitude Controller switch (seen here at the left) to the desired bombing run height. He then set the minimum height required on the Radio Altitude Limit switch to ensure the aircraft did not drop below that height.
The combined 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.
If the aircraft descended below this limit a red light would illuminate on the panel while a green light indicated the aircraft was too high. A yellow light indicated the correct selected height.
The centre knob of this instrument still turns to set the altitude between 50 to 300ft and while there is some minor paint chipping on the outside dial, the glass, display and case are in excellent condition.
This Grumman TBF Avenger Instrument comes complete with detailed Scale Model, Mango Wood Stand & Plaque plus Printed Fact Sheet featuring photo of instrument in aircraft cockpit.
Your TBF Avenger Radio Altitude Limit Switch, Original Recovery Curios Warbird Collectable includes:
*An upgrade to the larger and more detailed 1/48 scale model is also available in the hand-built and airbrushed plastic version for an additional $35 (Click on the 1/48 scale option)
Both the 1/72 & 1/48 scale hand-built and airbrushed plastic models are available with 'wheels & flaps up or down' and 'canopy open or closed' options with a choice of two Squadron markings and camouflage.
Upon order placement you will receive an email asking for your preferred configuration.
Your complete Recovery Curios Original Instrument Collectable is securely packed and delivery normally takes between 6 - 8 weeks approx.
Did you fly, crew or maintain a TBF Avenger or have a friend, colleague or family member who did? Check out our PERSONALISED ORIGINAL INSTRUMENT COLLECTABLE OPTION here.