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Source : http://www.ekco-electronics.co.uk/ASV19/ASV19.htm

The website mentioned above (http://www.ekco-electronics.co.uk) seems to have disappeared or at least historical pages aren't shown anymore.  The content of the EKCO page has been retrieved from http://web.archive.org and reproduced on Atlantic Air Combat™ pages for reasons of convenience.  The layout of this article might be edited, not its content.

The article below has been retrieved from : http://web.archive.org/web/20120328135340/http://www.ekco-electronics.co.uk/ASV19/ASV19.htm

ASV Mark 19 models A & B
By Chris Poole - April 2006

By the end of the war (WW2) it had become woefully apparent that there was a need to have a new 'fleet' Anti submarine aircraft since the Fairey Firefly, which had been converted into this role was showing that there was very little design development left in the airframe and it was also suffering from 'wartime' era radar.

This lead to the Admiralty issuing specification GR.17/45 for a new aircraft, which would have a ASV role, have two engines, be capable of carrying a range of weapons and have a new centrimetric radar suite, which could be capable of detecting submarine snorkels and periscopes in various sea states.

The result of this was the Fairey type Q, which was later to become the Fairey Type 17 before being renamed the Fairey Gannet and first flew in 1949 with the first production order being placed in 1951.

For the radar suite, research indicates that the radar to meet this requirement evolved from the immediate post war joint TRE (Telecommunications Research Establishment) EKCO research program to investigate the feasibility of CCWR (Cloud and Collision Warning Radar) the result of which was the Ekco E34 search radar set and since TRE knew of the potential of the E34, this radar was developed into the ASV-19A. One advantage of this being that EKCO would have been able to put forward a compelling commercial case for a low development cost as well as a considerably reduced development time. The photo below shows an initial design concept model of ASV Mk 19 made by RRE Malvern in order to determine the basic principles.

ASV Mark 19 A on display at the Fleet Air Arm Museum Yeovilton (Photo by the Author)
Photograph of ASV Mark 19 model found in the archives of TRE/RRE (Photo courtesy of Mike Dean)

It appears that the original design concept must have been for a 'POD' radar to be fitted as a wing mounting due to the conventional scanner dish arrangement (with a 150 degree azimuth sweep) and the existing 'POD' radar under the starboard wing of the American Grumman Avenger TBM-3E may have influenced the thinking.  It is believed that the EKCO team was lead by Jack Gard supported by Cyril Drew, Frank Oxborough, Ted Hankins, David Evans, Glyn Thomas, John Lloyd, Norman Tingey, Hugh Walton, Jack Halsall, Harry Horton (on loan from RRE), Hugh Green and Mike Start although it has not been possible to confirm these names other than it is known that this team were in place at Malmesbury in 1949 and would almost certainly have been involved to a lesser or greater degree.  While no manufacturing records exist to tell how many ASV Mark 19 units were manufactured, based on aircraft build numbers it is suggested that production of the ASV Mark 19 A amounted to 150 for the main system and 300 for the indicator unit. For the ASV Mark 19 B, circa 500 for the main system and 1,000 for the indicator unit.

The (grainy) photo on the right is the only known photo of the E34/E38 system and is reproduced from an old EKCO sales brochure.

It is believed that many of the components for the ASV Mark 19 were shared with the E34/E38, in fact examination of the photos of the E34/E38 show remarkable similarities to ASV Mk 19. The 'A' version of the radar was ready by the end of 1949 and was assigned forces reference number ARI-5834 with service acceptance trials of the radar starting in 1950 and the final report services report issued in 1952.  The radar was an X band system (centrimetric) operating on 9,240 Mc's using a pulsed magnetron with a 7 to 10Kw (peak) power output. The pulse width was 1 ?s with a Pulse Recurrence frequency of 700 p.p.s. The system used a reflector klystron with manual and automatic frequency control as the local oscillator.

Photo courtesy Southend Museum Service)

The intermediate frequency was 45 Mc's, the IF bandwidth was 2 Mc's and the beam width was 6 deg. at 3db. The max range was 40 nautical miles with range markers on the display indicator at 10 and 40 Nm with range measurement by fixed markers at intervals of 2 miles on the 10 Nm range and 5 miles on the 40 Nm range.

An interesting function both on the A and B model display screens was an 'OPEN CENTRE' facility on the 10Nm range, which advanced the starting time of the sweep with respect to the transmitter pulse. The effect of this was to give better discrimination in Azimuth for short-range targets thus allowing the operator to focus onto small targets at short range.

As with any sea search radars, clutter from sea states was (and still is) a problem. In an effort to resolve this, circuitry was introduced to help filter out these sea returns (which show up as bright patches). This circuitry was activated by the 'sea clutter' switch on the A model and the 'video filter' switch on the B model. Switching this in filtered out the low frequency parts of the signal and by use of the Brilliance and Gain controls the display could be improved for detecting targets at shorter ranges in certain sea states.

In February 1952, 703 Service Trials Unit issued a preliminary trials report (number 509/52 PRO reference ADM335/77), which detailed their findings of operating ASV 19B between October 1951 and January 1952, flying a total of 32 sorties over a 56˝ hour time period.

While the equipment was very much 'pre-production' standard equipment and in consequence had a number of niggling faults, it acquainted itself well and performed as well - if not better than the ASV mark 13 system installed in a Shackleton despite this system having 45Kw of power against the nominal 7Kw of ASV mark 19.

The trials showed that the radar could detect 'trellis topped' marker buoys at 14-17 miles range and track these targets at 12-14 mile range in sea state 3. When tested against shipping the detection and tracking ranges were considerably better, for example a small 1600-ton cargo vessel was detected and tracked bow on at a range of 34 miles in sea state 4.

When tested against a surfaced submarine, this was detected stern on at a range of 22 miles and tracked at 20-mile range in sea state 2. Against landmasses, the system was outstanding and typically 'Lands End' was recognised on the screen and tracked at over 40 miles range in sea state 3.

The photo on the left below shows a top down view of the ASV-19A scanner and TR unit showing the compact nature of the system. This photo makes an interesting comparison to the RRE/TRE model. The photo on the right below shows the ASV-19 A (type 28) indicator unit showing the bearing measurement fixed scale on the faceplate..

(Photograph reproduced from AP4400 - Courtesy of the Public Records Office - Kew) (Photograph reproduced from AP4400 - Courtesy of the Public Records Office - Kew)

A second variant of ASV-19 was also developed especially for the Fairey Gannet Mark's AS1 though AS6) having a full 360 degree sweep scanner unit, which also necessitated having a different indicator unit, this unit being a 'centre scan'.
This system was designated ASV-19B and while EKCO remained as the prime contractor for the overall system, there is no record of the scanner and display indicator being made by EKCO and it was almost certainly sub-contracted to EMI although no objective evidence has been found to confirm that EMI was the sub-contractor.
The photo on the right is the ASV-19B scanner unit. It is believed that this ASV-19B was ready by the end of 1952 and it was assigned forces reference number ARI-5838 with the AP manual being AP4401. This scanner unit rotated at approximately 40 r.p.m. producing a pencil beam. The beam width was 4 degree's in azimuth and 6 degrees in elevation at 6db.
The photo below (Photo courtesy of Steve Milnthorpe) shows the ASV Mark 19B type 101 indicator unit and the centre scan PPI display. As with ASV-19A, the maximum range was 40 nautical miles with range markers on the display indicator at 10 and 40 Nm with range measurement by fixed markers at intervals of 2 miles on the 10 Nm range and 5 miles on the 40 Nm range.

(Photo - Public Records)

By 1952 both radar variants were ready for service but unfortunately the aircraft was not mainly due to the production order for the Gannet not being placed until 1951.

This was mainly due to an Admiralty requirement for the aircraft to be reconfigured as the three seater (the original design was a two seater aircraft) to allow for a dedicated 'search radar operator', and the need to correct aerodynamic stability problems resulting from the radar operators canopy disrupting the airflow over the tail surfaces.

Nevertheless, training of radar operators was able to start using a T1 variant of Percival Sea Prince, which was produced to act as a flying classroom where a ASV -19 A was conventionally mounted in the nose of the aircraft with 3 scopes fitted on workstations in the cabin so that 3 radar operators/observers could be trained at any one time.

The Photo below, left, is of the 'Percival Sea Prince' TI at the Fleet Air Arm Museum at Yeovilton.  On the right is a T1 Sea prince configured as an ASV-19 trainer, showing two of the three display indicators.

(Photograph copyright www.britishaircraft.co.uk) (Photograph copyright the Gatwick Aviation Museum)

It was fortuitous that training was started since it became apparent that the Gannet was going to be late into service. Accordingly in 1953 the Royal Navy/FAA acquired 100 Grumman anti-submarine warfare versions of the Avengers under the Mutual Defence Assistance Program (MDAP). These aircraft were designated the Avenger AS Mk IV or AS Mk V, and were used in the ASW role until the introduction of the Gannet in 1955. In these aircraft the American radar was removed and replaced with ASV Mark 19A.

ASV-19A 'POD' installation in Grumman Avenger
(Photo reproduced from AP4400 - Courtesy of the Public Records Office - Kew)
ASV-19A observers installation in Grumman Avenger
(Photo reproduced from AP4400 - Courtesy of the Public Records Office - Kew)

The Gannet and the radar ended up having a long 'in service' life spanning 15 years between 1955 and 1970 in the Fleet Air Arm equipping 18 squadrons and it was also exported notably to Australia where it equipped 3 squadrons of the Royal Australian Navy. It was also exported to Indonesia and West Germany.

The schematic shows the installation in the Gannet
(Photo reproduced from AP4400 - Courtesy of the Public Records Office - Kew)
Photo reproduced from www.fly-navy.de/jets/seahawk taken from German Seahawk book details of which can be found at www.f-40.de/fset/f40.html.
These two photos reproduced from "Hawker Sea Hawk", a 4+ publication published by MARK I Ltd., PO Box 10, 10 31 Prague 10 - Strasnice, Czech Repubmic (c) MARK I Ltd., 1st edition, Prague 2001 - ISBN 80-902559-3-0

An interesting footnote is that in 1955, the West German 'Marine-flieger' bought 68 Armstrong Whitworth Sea Hawk jets. 34 of these aircraft were configured with ASV Mark 19A mounted in the front of the starboard underwing pod and designated as Seahawk Mark 101. For reasons not known, this system appears to have been called the EKCO E38 system

The Australian Experience

Records indicate that 33 Gannet AS-1 and 4 T-2 variant aircraft were sold to Australia equipping 724 Squadron RAN, 725 Squadron RAN, 816 Squadron RAN and 817 Squadron RAN.  These aircraft appear to have been based at RANAS Nowra when not embarked on HMAS Melbourne.  While there was a close relationship with the UK Fleet Air Arm, the RAN elected to train their own crews and rather than use the Percival Sea Prince, accordingly, for the radar operators a DC3 Dakota was modified as a crew trainer.

The following two photographs show one of the RAN Gannet survivors at the Queensland Aviation Museum Caloundra. Both of these photographs show nicely the ASV-19 retractable radome underneath the fuselage.

Photograph reproduced courtesy of
Greg Weir and George Canciani
Photograph reproduced courtesy of
Greg Weir and George Canciani

In writing this article, I would like to give a vote of thanks to Bob Geale, the Honorary Curator of the Australian Museum of Flight for his help and assistance in researching and compiling this article. I would also like to thank Catherine Rounsfell the Assistant Curator at the Fleet Air Arm Museum Yeovilton.