In Stock SKU: 2311

Rare Northrop P-61 Black Widow, General Electric Radio Altitude Indicator

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 USN and USAAF aircraft such as the SB2C Helldiver dive bomber, Grumman TBF Avenger torpedo bomber and the night fighter/ground attack interceptor, the Northrop P-61 Black Widow.

The AN/APN-1 was the USN and USAAF’s primary airborne frequency modulated, radar altimeter which was designed to emit a downward signal from the aircraft’s transmitter antenna. Significant components of the same system were also adapted by the British forces and found their way into Coastal Command Sunderland Flying Boats, Bristol Beaufighters and the Fairy Swordfish torpedo bomber. In fact the display components were also installed in a a number of British heavy bombers such as the Avro Lancaster and Halifax bombers and the De Havilland Mosquito for low level missions where exact ground height was essential for target bombing.

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 Northrop P-61 Black Widow Instrument comes complete with detailed Scale Model, Mango Wood Stand & Plaque plus Printed Fact Sheet featuring photo of instrument in aircraft cockpit.

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Your Northrop P-61 Black Widow, Radio Altimeter, Original Recovery Curios Warbird Collectable includes:

  • Original Warbird instrument
  • Highly detailed hand-built and airbrushed 1/72 plastic scale model of the aircraft,* 
  • Hand-crafted and beautifully finished 100yr, Far North Queensland Mango Wood display stand
  • Detailed, 2-sided, printed and laminated Instrument Fact Sheet detailing aircraft and instrument
  • Removable Magnetic Display Arm

The 1/72 or 1/48 scale hand-built and airbrushed plastic model is available with ‘wheels & flaps up or down’, ‘cockpit open or closed’ in a choice of two Squadron markings and camouflage.

*To opt for the larger, more detailed 1/48 scale model simply click on the 1/4 scale tab at the top of the page

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 4 - 6 weeks approx.

Did you fly, crew or maintain a Black Widow or have a friend, colleague or family member who did? Check out our PERSONALISED ORIGINAL INSTRUMENT COLLECTABLE OPTION here.