US IRST devices AN/AAA-4, AN/AAS-15 and more

[overscan (PaulMM)]

There are definitely some mistakes in it, snd its sometimes a bit academic (a historian, not an engineer), but the author has some good sources. It feels like it needed a good editor.

 

[Heatloss]

Worth noting that the later PbSe units had the Germanium coated(?) windows.

Correction. Visible band AR coating, likely extending into the SWIR range. Silicon window.

 

[Heatloss]

During the mid-1960s timeframe of Project Bold Journey, the F-102A was undergoing similar upgrades in sensors and missiles while a retractable IRST was coupled with the more advanced weapons of the F-106 to provide the same tactical advantages for American interceptors. The Hughes IRST was reportedly sensitive enough to detect a Soviet Tu-95 “Bear” bomber from the front hemisphere due to the massive heat signature produced by its NK-12 turboprop engines and it was not unusual to detect targets on the IRST before achieving a lock with the radar. Although the IRST in F-101B maintenance manuals is referred to generically as the “IR Receiver and Closed Cycle Cooling System”, the same basic system is referred to as the “90-C IR-search-track set” for the F-102A and the AN/AAS-15 for the Vought F8U-2NE Crusader serving with the U.S. Navy. The downside of the Hughes IRST was that, at least for its first year of service, it was not at all reliable and spare components were in very short supply, often forcing squadron-level maintainers to use field-expedient solutions to keep the systems functioning.

http://fighterwriter101.blogspot.com/2015/02/something-extra-upgrading-f-101b-fire.html

 

[quinn whitsitt]

thanks for the info heatloss

 

[Heatloss]

Follow-up on AAA-4. I believe this was either an Avion Model 333 Automatic Search and Point system or a derivative thereof. The description of the 333 ASP aligns with the physical characteristics of the extant examples of AAA-4 that have appeared online, and aligns with the reported performance of the unit. Avion was developing the Model 333 ASP at the same time that the Aero X1A fire control system was being developed by the USN, and Avion was one of the contractors selected to develop an IRST. The dates of the relevant reports here being only a few months apart make me confident that AAA-4 is a 333 or 333 derivative. I will follow up with the Smithsonian to see if they have any records from the Avion division of ACF Electronics.

https://apps.dtic.mil/sti/tr/pdf/AD0367910.pdfhttps://archive.org/details/f-102-part-12-box-1/F-102 Part 9 - F106-F102 DS/page/n1/mode/2uphttps://archive.org/details/f-102-part-12-box-1/F-102 Part 9 - F106-F102 DS/page/22/mode/2up

 

[overscan (PaulMM)]

Advert for Avion, March 1957

 

[overscan (PaulMM)]

Infrared Tracker System Tests Readied at WADD

USAF’s Wright Air Development Division soon will begin evaluation tests on prototype model of the AN/AAR—21 infrared search-track system for interceptor use, developed by International Telephone & Telegraph Corp.

System employs two infrared tracking heads to provide both target bearing and range information. WADD does not disclose the type of infrared detector
used, but says it is cooled to liquid nitrogen temperature.

AWST 18 April 1960

 

[overscan (PaulMM)]

William H. Wallschlaeger was born in Milwaukee, Wisconsin, on 17 May 1935. He graduated with honors from Michigan State University in 1957, with a Bachelor of Science degree in electrical engineering. After initial employment with Minneapolis Honeywell, he worked at the A. C. Spark Plug Division of General Motors Corporation, designing ground support equipment for the W S31 SA (Thor) program. He joined ITT Industrial Laboratories in 1959 to work on the AN/ AAR-21 Infrared Search Track Set.

https://www.worldradiohistory.com/Archive-ITT/60s/ITT-Vol-40-1965-04.pdf

 

[overscan (PaulMM)]

The infrared sight, AN/ASG-14, for the F-104 "Starfighter" constitutes an Infrared sight construction, including an infrared system of detection, an electron amplifier and a projection system for visual indication of the target (9]. The projection system of the sight, after corresponding conversion and amplification, transmits an Infrared image of the target to a reflective glass optical sight. A sensitive element (PbS) is placed outside the cabin before bullet-proof glass and is covered by a little of the photoresistor entrance window, transparent in the region of sensItivity. The pilot observes on the reflective glass of the optical sight simultaneously a mark from the target and a sighting mark whose position in the field of sight is calculated by a computer of optical sight. This allows him to carry out an attack on the target at night just as if the target were visible directly to the eye. In this sight, thanks to the large field of sight, there is no necessity for special scanning device since on the reflective glass of the sight are observed simultaneously all targets in the field of sight of the receiving head. The pilot in it this case executes the function of selection, distinguishing that target which is necessary to attack.

In a more later infrared sighting station, the AN/AAR-21, developed by Hughes Aircraft Co., the scanning system and tracking are divided. As a sensitive element in the sighting station is applied a lead sulfide photoresistor, cooled to the temperature of liquid nitrogen. In distinction from station AN/ASG-14 this station makes it possible to measure distance to target with the help of two tracking heads on infrared beams.

https://apps.dtic.mil/sti/tr/pdf/AD0610765.pdf

 

[overscan (PaulMM)]

Note the sources giving AN/AAR-21 as an ITT product are ITT and AWST, the source describing it as a Hughes product is a Soviet report on Western Infrared development.

Also note that AN/ASG-14 is the designation for the F-104 sighting system as a whole, including radar, gunsight and IR sight.

 

[overscan (PaulMM)]

ITT had an earlier product, the AN/AAG-5 IR Search Set as well as the AN/AAR-21 IR Search-Track Set.

https://tubedata.edebris.com/sheets/188/f/FW202.pdf

 

[overscan (PaulMM)]

A major system program, the ASG-18 tracker for the F-108 died early in this period when the Air Force canceled the aircraft. SBRC had developed this unique tracking concept based on an idea of project engineer John Reed, who had radar experience on the SCR584 in World War II. This radar system employed an offset spinning dipole at the focal point of a parabolic dish to achieve tracking error signals. He applied this concept to passive infrared systems to achieve better rejection of spurious targets caused by variations in the infrared background radiation by using a line array of detectors at the focal plane. The conventional system imaged the entire scene on a rotating reticle, which caused signals to be generated from all variations in the infrared scene. In order to generate tracking information he made the detector array in a cross form and nutated the field of view. The servoed gimbals drove the center of the field so that the target was equispaced on the arms of the cross. Searching was accomplished by a raster scan until the target was detected. SBRC developed the tracker, called the ‘beer can tracker’ because of its size, and Hughes Culver City developed the remainder of the system. A PbSe detector array, available only at SBRC, operated at liquid nitrogen temperature, using a liquid nitrogen transfer system. Although the original application was terminated, Hughes continued work using company funds and later received government support and developed search-track sets, called 90-C, 100-C, and S71N, which were used on the F101, F106 and foreign aircraft. SBRC supplied the PbSE and later InSb arrays in glass dewars which were cooled originally by liquid nitrogen transfer and later by Joule-Thomsen cryostats.

Early in this period the replacement for the ASG18 Search Track Set was being developed by Hughes with SBRC supplying the lead selenide cross array detector and the liquid N2 transfer cooling system. This detector was installed on a stern which fit in an outer dewar. This arrangement (called a double-barreled dewar) allowed the dewar to be outgassed at high temperature independent of the detector. This program finally led to the 90C, 100C, and the Swedish 71N systems. By 1962 the design was qualified and production started. At first Hughes Tucson had difficulty with these detectors and returned many of them. When we finally got to the bottom of the problem, it was found that the drawings called for a precision honed inner bore. The Tucson inspector was using a solid plug gauge to measure the internal diameter while we had checked it out with a ring gauge, which did not guarantee that the hole was precisely straight. The detectors were returned as being open circuit after the inspector had pushed hard enough on the plug to break the glass in an effort to pass the unit. All this trouble and expense for a hole that only had a hose glued in it! Generally, this detector production went very well and the program had a long life.

The first significant program using SBRC crystal detectors was for the Hughes Phoenix Search Track system for the Navy F-14. The program started using an 8-element photoconductive InSb array which SBRC and Minneapolis Honeywell had contracts to develop. The early units were delineated by sandblasting and both suppliers had a great deal of difficulty with stability and other problems. The program office signed up with SBRC and satisfactory detectors were finally delivered for prototype use after a change was made to the photovoltaic mode. This program lasted for a long time even though it never involved large numbers.

The Hughes Phoenix detector program struggled in the first part of this period [1960s] with technical difficulties and funding problems. Prototype deliveries did support the system development but there was some customer irritation. In 1967 the detectors were changed to the photovoltaic mode. Because the drawings were now subject to tight change control, this change had to be sold as a “minor process change”. After lengthy start-up problems prototype deliveries of excellent detectors were made at the end of the period. No production developed from these efforts but the knowledge gained was beneficial for future InSb programs.

The business of casting infrared transparent domes was transferred from Hughes Newport Beach in the beginning of this period. Infrared missiles required windows on their seeker heads which were transparent to infrared radiation in the three-to-five micron region, were hemispherical in shape, and rugged enough to withstand the flight environment. Generally the domes were made of pressed fluoride or sulfide compounds or polycrystalline Si. The Hughes method used induction melting of Si in a graphite mold, which provided blanks close to the final shape and required only a small amount of polishing. A new approach of melting MgF2 and casting in a manner similar to the Si approach failed because the coefficient of thermal expansion was not identified in all directions in MgF2. The business finally prospered. Domes were supplied to Hughes programs, such as AIM-4D and 90C Search-Track Sets, and to foreign versions of these programs. Special castings were made of Ge for long wavelength space and experimental radiometers. As orders tailed off the business was finally sold.

https://sbrc-sbrs.com/robert-talley-july-3-1995/

 

[overscan (PaulMM)]

National Defense Transportation Journal, Vol. 16, No. 3 (May-June 1960),

 

[overscan (PaulMM)]

Earliest IRST type device I've found is the RCA AN/AAR-5. It dates back to 1949, and test units were constructed in 1953.

The purpose of this contract is the development of two types of airborne infrared receiving sets and the design and construction of models of each type for evaluation by the Navy. 2. The AN/AAR-4 is a tail-warning device. Its purpose is to detect and furnish directional information of pursuing aircraft in sufficient time for the pilot to take evasive action. The AN/AAR-5 is an intercept device. It permits forward search and tracking of reciprocating or iet engine aircraft at relatively long ranges. The detailed requirements for each type are covered by Bureau of Aeronautics Specifications XEL-72 and XEL-87, respectively.

https://apps.dtic.mil/sti/tr/pdf/AD0044147.pdf

 

[overscan (PaulMM)]

 

[overscan (PaulMM)]

Hughes Advert (1963/1964)

 

[overscan (PaulMM)]

Postscript:

Infra-Red Search and Track System (IRST)

In the 1970s, Hughes equipped several hundred US Air Force F-101, F-102 and F-106 aircraft with Infra-Red Search and Track (IRST) systems. In mid-1985 Hughes proposed transferring 300 of these sets to equip F-4s of the US Air National Guard, at a total cost 1n the order of $30 million which. according to Hughes would be one-tenth the price of a new system. The IRST system was flight-tested by the 119th Fighter Interceptor Group in 1985.

Jane's Avonics, 1987-88

 

[overscan (PaulMM)]

One item of equipment found on early production F-14s but soon deleted was the AN/ALR-23 infrared (IR) search and acquisition set. The IR seeker was located under the nose of the aircraft, and could be slewed independently of the radar antenna, or slaved to the antenna for co-ordinated tracking. The indium antimonide detectors were cooled by a self-contained Stirling-cycle cryogenic system, while the rest of the system was cooled by the same chilled oil.used by the Phoenix missiles.

The IR seeker proved ineffective and difficult to use, so it was deleted early in the production run.

Dennis R. Jenkins, F-14 Aerofax

 

[Heatloss]

Indium Antimonide was discovered in 1951. InSb missile seekers were absolutely on the way in the late 50s in the UK, entering service in 1964 on Red Top.

I went back to the sources I cited, and in fact Paul Crickmore is vague on timing with the Hughes Indium Antimonide sensor work. Might be early work leading to the Hughes AN/ALR-23 F-14 IRST?

Paul Crickmore - Blackbird, Beyond the Secret Missions.

PbSe and PbTe were very much less sensitive than PbS so constructing long range sensors with them was difficult.

Well, here's one that threw me for a loop. I was totally wrong.

I think the timeline that I implied from Hughes after Howard was far more compressed than I thought. If GAR-4A was using cooled InSb, I see no reason that the IRSTs should be using PbSe. This image was supplied to me by someone on Twitter who was given this sheet by an ex-Hughes employee.

 

[overscan (PaulMM)]

Well, here's one that threw me for a loop. I was totally wrong.

I think the timeline that I implied from Hughes after Howard was far more compressed than I thought. If GAR-4A was using cooled InSb, I see no reason that the IRSTs should be using PbSe. This image was supplied to me by someone on Twitter who was given this sheet by an ex-Hughes employee.

https://www.secretprojects.co.uk/threads/infrared-seeker-technology.193/#post-551209

 

[Heatloss]

https://www.secretprojects.co.uk/threads/infrared-seeker-technology.193/#post-551209

Most of that additional spectral response for PbSe falls in a low atmospheric transmission area. For the visible region, InSb is quite a bit more sensitive.

 

[overscan (PaulMM)]

Yes, for best range in rear aspect on hot tailpipe, 1-2 microns, uncooled PbS is hard to beat. Uncooled PbSe doesn't seem better.

I'm not seeing why cooled InSb is better than cooled PbTe or PbSe from these graphs though.

 

[Heatloss]

Yes, for best range in rear aspect on hot tailpipe, 1-2 microns, uncooled PbS is hard to beat. Uncooled PbSe doesn't seem better.

I'm not seeing why cooled InSb is better than cooled PbTe or PbSe from these graphs though.

It's consistently slightly more sensitive than PbSe, but those graphs are super inconsistent based on the time that they were made. InSb was supposedly hard to make right for a while, though I don't know how legitimate that claim is because it's "word of mouth" from someone in the industry.

Either way, I'll have to check a different paper from a similar time(1960-1964) tomorrow. I've got it somewhere on my computer.

 

[overscan (PaulMM)]

Definitely seems like Sidewinder's success with PbS (cooled and uncooled) skewed perceptions.

I only recently discovered that R530, and Magic I used cooled InSb seekers. Magic II had a multielement seeker that improved range, but still InSb.

https://www.secretprojects.co.uk/threads/sat-infrared-seekers-for-matra-r-530-and-magic-aams.45135/

 

[overscan (PaulMM)]

https://www.aef.se/Avionik/Notiser/Flygradarinstallation_J35F_J35J_IR-spanare71N.htm

The last two hunting versions of the aircraft Draken, J35F2 and J35J, were supplemented with an IR spanner after a specification from the Royal Air Administration, KFF. It was developed to some extent by LM Ericsson, LME, though with influences by an American IR spanner, developed by Hughes Aircraft Company, HAC.

The IR spanner was fully integrated with the Swedish scouting radar PS-011 antenna system.

The IR Speaker MS in its IR capsule, IR signal unit, servo amplifier and power units were manufactured and delivered by LME, while the indications were presented on the radar's indicator, manufactured by Svenska Radioaktiebolaget, SRA. A cooling machine for cooling down MS Detector was manufactured by Westinghouse.

The operating agencies were located on a radar panel, a hand control and a weapon panel that was manufactured at Swedish Aeroplanaktiebolaget Saab.

The IR Speaker worked in the wavelength area 3.2-4.7 micrometer and its main task was to convey relevant target movements to the radar for forwarding to the sight S-7B3/31 at the time of shooting with hunting roofs in Direktfall Da or Hi Curve, in the case of a flight height. Slave signals to the radar antenna and to the hunting robots RB27 and RB28.
It could also be used for target tension.

The equipment admitted scanning in various scouting programs, slave from the radar's antenna and a program for goal follow -up in two coordinates, side and height.
The IR-Save's MS-S's total discharge none was 120 degrees in the side plane and 60 degrees in the height level, centered to the aircraft's nose direction.

Targeting was presented when scouting on the radar's indicator type B which specified the direction to the target and in the follow -up program, the target information was supplemented with control information to optimal firing point on an indicator type F.

The connection of the IR spanner as a goalkeeper and goalkeeper was performed from the Radar's hand control and the basic settings were made on the radar panel.
Extensive and off by the IR spanner and its goalkeepers were made on the weapons panel in the cabin.


Written by Göran Hawée 2019-08-18

 

[Al Hislop]

I bought several AAA-4 receivers from a surplus dealer in the LA area back around 1970. The pictures attached are of what I have found in my attic after about 55 years. The modules marked ACFE and the cage code on the nameplate should lay to rest any question about the manufacturer. The system had a conical scan that was produced by a slightly tilted rotating sub reflector in a Cassegrain optical system. I seem to recall reading that the "star" pattern on the detector input face allowed the system to determine how far off-center the target was, by looking at the frequency of the signal as the sensed "dot" of the target passed the sensitive areas of the star. The star pattern has fewer sensitive stripes near the center, so the frequency would be lower as the object moved to the center of the field of view. I also recall that the detector was InSb, but take that with a grain of salt. I believe the radome is Ge. A hand-held IR thermometer sees right through it.

 

[LifeBeyondLiving]

I've been doing some research on USN surface ship IRST systems and came across this mention of a podded Seafire fc unit for LAMPS from 1978, appears to have dropped off the map afterwards though.