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APQ-81: radar for the Missileer

overscan (PaulMM)

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Some details of the APQ-81 radar from the Missileer

Targets tracked simultaneously: 16
Frequency: C band
Average power: 2 kW (to be increased to 5kW later)
PRFs: 65kc/s, 11/10ths of 65kc/s, 11/9ths of 65kc/s
Aerial diameter: 60 in
Beamwidth: 2.5 deg
Range gates: 10
Scan limits: +-60deg in azimuth, +48 to -40deg elevation.
Frame time: 2 sec
0.3sec (2 x 0.15 sec) turnaround time, of which each half is used to transmit guidance commands to missile.
Aerial search: 30 deg x 5deg
Scan pattern: 2 bar scan
time on target: 60-70msec
Number of filters: 10 x 2 x 30
Maximum unambiguous range: 112nm
Target range rate: 215 - 2900 knots
Target altitude: 0-100,000ft
Range, 90% probability on 5 sq m target: 72nm

IBM 704 computer
Reflex klystron oscillator with 4 cavity klystron amplifier.

An early method of range while search was attempted. The radar switched between 3 prfs and then attempted to detect which range gate the signal is received in (output from doppler bank). However signals could overlap two range gates at certain distances. THey considered either measuring the number of times threshold was exceeded in each range gate, then assuming that the range gate where the threshold was exceeded most often was the correct one, or alternatively choosing one and then comparing the range information for consistency with previous range information.

Westinghouse weren't completely happy with the method of range measurement and were considering a linear frequency modulation to the transmitter instead [FM ranging].
 

Meteorit

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Re: APG-81: radar for the Missileer

I think you mean APQ-81; AN/APG-81 should be the radar for the F-35 Lightning II (which I don't think uses klystrons :)).
 

Archibald

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... which rise an interesting question : why some radars are APG- when others are APQ- ? ???
 

Meteorit

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It seems that at least since the early 1970s fighter radars have been designated AN/APG, while AN/APQ has been used for various other radar types (attack aircraft and bomber radars, terrain following radars etc.) I think the age of the AN-system shows here, as specialized "Fire Control Radars" (what APG means) are hardly made anymore and most radars are at least somewhat "multipurpose".
 

TinWing

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Is there ever been a reference to French interest in the Missileer's radar? The 1960 MN TALP requirement was very similar to Missileer, albeit in a lighter platform suitable for the Clemenceau class - although I have never found any references to the radar or missiles meant for the subsonic TALP?
 

overscan (PaulMM)

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Developing New Radar Techniques
Fegely:

It’s 1955 by now and I became supervisor in the radar section.

Hochheiser:

So by this time had you solved the—?

Fegely:

Antenna problems? Ok for today’s systems but not for the future.

Hochheiser:

Okay. So now we’re off from BOMARC onto - - .

Fegely:

Developing techniques that will be needed for the next generation Navy, Air Force or Army radar.

Hochheiser:

Ah.

Fegely:

You’re doing good if one out of five ideas will be key to winning the next radar.

Hochheiser:

[Interposing] So it’s not that closely tied to any current product?

Fegely:

No. We did assist solving some production problems. But our task was to bring in the next one. Design Engineering Dept. handled production problems.

Hochheiser:

Okay. And about when is this?

Fegely:

It took about two years to convince the Navy we were the ones to develop their long range track-while-scan C-band pulse Doppler radar, the APQ-81 which started in 1961.

Hochheiser:

Okay.

Fegely:

The key techniques for multiple target track-while-scan were changing the prf several times during the antennae beam dwell time, a very low side lobe antenna, digital processing to establish track files, and multiple range gated channels to reduce clutter. [Data from Pete D'Anna: After having been used for the BOMARC seekers, the Pulse Doppler technology in] theAPQ-81’s [pioneering pulse doppler, multiple target, track while scan system] was the [principal] base[line] for our future fire control systems and the driver for the AWACS radar. [The APQ-81was originally used as the radar fire control system for the Bendix long range air to air Eagle Missile System. Through all of these early programs it was] Johnnie Pearson’s persistence [that] got the hardware and test done on time [as was his later skillful management of the AWACS fly-off at Boeing which won this key major program for Westinghouse. Initially a young engineer by the name of Bill Jones explored the application of the AN/APQ-81’s technology to resolving the basic AWACS detection and tracking problem. When] Bill Skillman [became available to the program, his diligent pursuit of the many ramifications for fully developing the full potential of Pulse Doppler techniques earned him the well deserved title as the “Architect” of the AWACS radar system. In his following work on the AWACS program, he was the] technical Guru [assigned to] “Keep AWACS Sold” to the Washington crowd. [It t]ook years to get him back on new programs. Can’t forget Charlie Calhoun’s Chinese Remainder Theorem or Gwen Hays' tenacity to get it done. On the management side, Pete Waterman (NRL) wanted Westinghouse to use a new (to Westinghouse) Program Manager Concept. After a bit of in-house deliberation knowing Pete would not give up,Wx agreed and I became the first Wx Program Manager. I obviously got my guidance from Pete. We did get a follow on program from the Navy–FWCS (Future Weapons Control System). It was flight tested in an A3D.

 

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