Roof Rat Posted November 5, 2020 Share Posted November 5, 2020 Hello all Doe's anybody know what this is on the roof of a JASDF E-2D Hawkeye is please. Cheers in anticipation Keep safe RR (Chris) Link to comment Share on other sites More sharing options...
Red Dot Posted November 5, 2020 Share Posted November 5, 2020 Interesting, although I don't know what it is for, as the first JASDF aircraft don't have it fitted. Where did you find the picture, and I will check some more? Andy Link to comment Share on other sites More sharing options...
Roof Rat Posted November 5, 2020 Author Share Posted November 5, 2020 Hello Andy Thanks for the reply it came from Airfighters.com https://www.airfighters.com/photo/219969/M/Japan-Air-Force/Grumman-E-2C-Hawkeye/34-3459/ Cheers Chris. Link to comment Share on other sites More sharing options...
AV O Posted November 5, 2020 Share Posted November 5, 2020 (edited) The caption says it is an E-2C. Indeed it doesn't carry the USG-3B antenna on the belly : https://commons.wikimedia.org/wiki/File:U.S.NAVY_E-2D_Advanced_Hawkeye(168991)_of_VAW-125_USG-3B_CEC_antenna(AS-4467)_left_rear_view_at_MCAS_Iwakuni_May_5,_2018.jpg Edited November 5, 2020 by AV O Link to comment Share on other sites More sharing options...
Red Dot Posted November 5, 2020 Share Posted November 5, 2020 The caption is clearly wrong as it has the new props fitted to the D model. JASDF E-2Ds are not fitted with the AN/USG3B equipment either. I will see what I can find out about the sensor above the cockpit Andy Link to comment Share on other sites More sharing options...
AV O Posted November 5, 2020 Share Posted November 5, 2020 (edited) E-2C Group 2 1991, radar / avionics upgrade. BuNo. 164108 / 164112 BuNo. 164352 / 164355 BuNo. 164483 / 164497 - 3 to JASDF. BuNo. 164621 / 164626 - 1 to Egypt. - 3 to JASDF as 34-3459 / 34-3461 http://www.uswarplanes.net/hawkeye.pdf Edited November 5, 2020 by AV O Link to comment Share on other sites More sharing options...
Red Dot Posted November 5, 2020 Share Posted November 5, 2020 Apologies AV-O, I was half right Andy Link to comment Share on other sites More sharing options...
Roof Rat Posted November 5, 2020 Author Share Posted November 5, 2020 Hi to you both Sorry for the confusion over the C/D prefix, my fault. Cheers Chris. Link to comment Share on other sites More sharing options...
Red Dot Posted November 5, 2020 Share Posted November 5, 2020 We've all learnt something! Still waiting for answer to your original question though Andy Link to comment Share on other sites More sharing options...
AV O Posted November 5, 2020 Share Posted November 5, 2020 (edited) Aircraft from other batches (previous ou later) also have this antenna - or is it a probe ? see # 458 / 2nd row center - : https://www.qwant.com/?q=JASDF E-2C Hawkeye update&t=images Edited November 5, 2020 by AV O Link to comment Share on other sites More sharing options...
RAF4EVER Posted November 5, 2020 Share Posted November 5, 2020 2 hours ago, Roof Rat said: Hi to you both Sorry for the confusion over the C/D prefix, my fault. Cheers Chris. Should be suffix ,pre means before.😁 Link to comment Share on other sites More sharing options...
Red Dot Posted November 17, 2020 Share Posted November 17, 2020 Sorry, but I can't find out what the sensor is, but there is a better picture here. It seems it is quite old though. https://www.airfighters.com/photo/241931/M/USA-Navy/Grumman-E-2C-Hawkeye/163693/ Andy Link to comment Share on other sites More sharing options...
Roof Rat Posted December 11, 2020 Author Share Posted December 11, 2020 Hello all Mystery solved!! Thanks to a PM conversation I've been having with wdossel he has come to the rescue, please see his reply. The antenna that you have circled is for the Airborne Microwave Refractometer (AMR). It had limited installation on Group 0 E-2Cs via Airframe Change 308 (AFC 308) and was eventually discontinued and not included on later models of the C or on the D. More specifically, what is circled is the tuned cavity assembly that contains a sampling cavity whose resonant frequency is directly a function of the refractive index of the atmosphere passing through it. Every 1.7 seconds the atmosphere is sampled throughout the flight profile. The aerodynamic housing also contains a temperature sensing device and the necessary hardware to convey the microwave RF signal (normally 9.4 GHz) through the cavity tot he detector hardware. The purpose of the AMR (in theory) was to measure temperature/pressure on climb out to station and determine the presence of either reflective or refractive layers. Those layers (invisible) affect radar propagation and the theory was you could predict propagation effects if you could measure atmospheric data as you flew out to station. It was a nice theory but ran into a brick wall in practice because all you were getting was a snapshot in time given the dynamic nature of the atmosphere (heating and cooling alone over the course of the day). The installation was dropped on future aircraft and those that had it basically left the installation in place even though it was no longer supported. That's why you won't see it on later models. Checkout his profile he knows what he's talking about. A big thank you to him for his help. Cheers RR (Chris) 1 Link to comment Share on other sites More sharing options...
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