Around 1954, the RCN started to look for an aircraft to replace the obsolescent fleet of Avengers which had served the navy well. A prime requirement of the new aircraft was that it had to be small enough to operate from a British Majestic class aircraft carrier. The RCN would soon be acquiring HMCS Bonaventure, an example of this class.

The aircraft that was chosen was the Grumman S2F Tracker which first flew in 1952 then susequently became operational with the USN. Initially there was talk that the RCN aircraft would be acquired directly from Grumman, however, the Canadian political community wanted them to be built under licence in Canada. In 1954, de Havilland Canada entered into a contract to build Trackers under license to replace the outdated AS 3M and TBM-3W2 Avengers being used by the Royal Canadian Navy. Subcontractors all across Canada built components which were shipped to the de Havilland plant in Downsview, Ontario for final assembly.  A total of 99 Canadian-built Trackers would enter service starting in 1956. From 1957 onwards, these aircraft operated from the newly-deployed aircraft carrier HMCS Bonaventure and various shore bases.

Tracker, serial number 1501, is especially noteworthy because it was the first Tracker built for the RCN. It actually started out as a US Navy Grumman-built S2F-1 purchased by de Havilland Canada to verify the integrity of the production jigs and tooling supplied by Grumman. Following its pattern verification role, the aircraft received the serial number X-500, the “X” indicating its test function and “500” being a contraction of its interim RCN serial number 1500. The X-500 was accepted for the RCN on 13 December 1954 and was used for testing a wide variety of avionics and anti-submarine systems both at de Havilland (Toronto) and the National Aeronautical Establishment at Uplands (Ottawa). X-500 was also used to evaluate a stream of Engineering Change Proposals from Grumman's own evolving Tracker evaluation program. As Canadian production progressed, de Havilland used X-500 to verify the installation of subcontractor-built assemblies and fabrication details.

By October 1956 the RCN had re-serialled X-500 as 1501. De Havilland brought the aircraft closer to Canadian CS2F-1 standards during the final month of 1956 and first flew in this configuration on 8 January 1957. The RCN allocated 1501 to the Naval Air Maintenance School (NAMS) on 26 April 1957 where it became instructional airframe A706 used to train maintenance personnel. This was the only American airframe acquired by the Canadian government and no Grumman-built assemblies were used in the production of the following 99 Canadian Trackers. Tracker 1501 is currently (2009) being refurbished by the Shearwater Aviation Museum.

1501 RCN Employment Record:

Taken on Strength:         18 Dec 55
With VX 10 squadron:   18 Dec 55, 27 Sept 56, 8 Jan 57
With NAMS:                  29 Jan 57, 29 Mar 68
Struck Off Strength:        17 Jan 72

Grumman S2F with RCN marking 'X500' is undergoing evaluation trials and equipment tests at the de Havilland plant which is today surrounded by the city of Toronto. (A  de Havilland Aircraft Company photo)

The Tracker represented a marked improvement in the evolution of carrier-based ASW aircraft.  The job that previously involved two aircraft (an Avenger "Guppy" and  a "Scrapper") would now be performed by one.  Designed expressly for the purpose, it was powered by twin engines, and at long last, the Navy possessed an aircraft that was equipped with a searchlight.  The most recent ASW embodiments of the AS 3M Avenger were carried forward to the Tracker, including AN/ASQ-8 MAD, AN/UPD-501 radar direction finder, and AN/SSQ-2 sonobuoys along with the AN/ARR-26 sonobuoy receiver.  The compact AN/APS-38 air-to-surface radar replaced the APS-20/APS-4 combination employed by the "Guppy-Scrapper" team. Also carried, was the usual array of ASW disposable stores: marine markers, smoke and flame floats, homing torpedoes and depth charges.  Like the Neptune, it was also armed with rocket projectiles beneath the wings, but the "Scrapper's" wing-mounted guns, of dubious value in post-war ASW to begin with, were dispensed with in the Tracker.  The CS2F-1 entered RCN service with VS 881 Squadron in February 1957.  The first Tracker to come aboard  with VS 880 squadron, arrived in October of that same year. An updated version, the Mark 2 with its improved AN/APN-502 search radar, new tactical equipment such as dispensers for the PDCs (Practice Depth Charges) used in EER (Explosive Echo Ranging) , a sonobuoy homer and a new autopilot, arrived on the scene in 1960.

DESIGN FEATURES

The Tracker incorporated many unique design features. Particularly significant, was single-engine performance in the event of an engine failure on the opposite side. To allow the aircrew to maintain a balanced flight and permit a single-engine carrier approach and landing, it was fitted with a large vertical stabilizer and rudder. The latter was split vertically into two sections. The forward section was hydraulically actuated during take-off and landing and was required during single engine operations to supplement the manually operated rear rudder section.  An additional hydraulic booster was added in the tail assembly to reduce rudder effort required in the case of an engine failure at low takeoff speed and high power. This was known as SERA [5] (Single-Engine-Rudder-Assist).
Those engines and props were something else on such a small airframe and without the big rudder and SERA, a   torque roll was almost guaranteed unless the pilot REDUCED power on the good engine.

The wing control surfaces included flaps which spanned over 85% of the trailing edge; circular arc spoilers supplemented the relatively smaller ailerons. Lift was augmented by employing fixed, leading-edge slats.

Using hydraulic power, the multi-spar wings could fold asymmetrically above the fuselage. This allowed the wing span to be reduced from 72 feet, 1 inch with wings spread to just 32 ft. 10.5 inches when folded. Also noteworthy was the use of large under-wing nacelles to house the Pratt and Whitney nine-cylinder radial engines and to provide space for the main undercarriage and rear-launched sonobuoys. Another unique feature was the search radar, powerful enough to detect submarine snorkels, using an antenna small enough to fit into a retractable "dustbin" radome beneath the rear fuselage. Non-acoustic submarine detection equipment included an Electronic Counter Measure (ECM) suite which could detect any radio transmissions in the SHF bands which were initiated by ships or submarines operating on the ocean surface. A retractable Magnetic Anomaly Detection (MAD) boom allowed the aircraft to detect a submarine's underwater position by measuring the variations in the earth's magnetic field caused by large underwater metal objects. A steerable 70 million candle power searchlight was installed in a fairing beneath the starboard wing. The pilot/co-pilot cabin, located just forward and below the wings, had superb visibility and the aircraft included two "sensor" systems operators.

VARIANTS

CS2F-1

Initial production run was based on the Grumman S2F-1 aircraft design. Fourty-two were built by de Havilland Canada serialled 1502 to 1543 (DH-01 to DH-42). According to both RCN and de Havilland histories, the first CS2F-1 (#1502) was taken on strength on 12 October 1956 and the last CS2F-1 (#1543) taken on strength 17 July 1958.

In 1960, seventeen active-duty CS2F-1's were transferred to the Royal Netherlands Navy.  In 1964, a pair of CS2F-1's  (s/n 1534 and 1540)  were stripped of armament and ASW electronics to reduce weight  and converted to transports used for Carrier Onboard Delivery (COD). These conversions allowed mail and staff to be transported to and from HMCS BONAVENTURE and facilitated the movement of ship's company ashore for compassionate reasons. The COD aircraft included additional seats which allowed it to carry a crew of two and six passengers.

The Canadian version of the Tracker differed from the USN counterpart mainly by adding JULIE/JEZEBEL acoustic anti-submarine search equipment. The first Canadian built aircraft delivered with this equipment flew at Downsview on 31 May, 1956.

All research and testing for the conversions to the -2 and -3 aircraft were performed by Experimental Squadron Ten (VX 10).

CS2F-2

An improved version of the CS2F-1 with Litton Industries tactical navigation equipment,  improved Magnetic Anomaly Detection (MAD), radar systems and minor airframe refinements. There were around 100 improvements overall. Previously, tactical navigation was provided by the co-pilot using a manual plotting board. The inclusion of this first generation automated navigation equipment provided an enhanced level of accuracy over large open ocean areas by providing automatic computations of position when the aircraft was actively pursuing a submarine. This version looked almost identical to its forerunner on the exterior. Fifty-seven were built by de Havilland Canada serialled 1544 to 1600 (DH-43 to DH-99). The first CS2F-2's entered service with the RCN in January 1960. As they were taken on strength, they gradually replaced the older CS2F-1's .

CS2F-3

The RCN developed further improvements to the Tracker, which resulted in Fairey Aviation substantially modifying fourty-five CS2F-2's to a new  CS2F-3 designation.. The CS2F-3 featured a second generation AN/ASN-501 tactical navigation computer, a Marconi AN/APN-503 Doppler radar, improved Jezebel and Julie submarine detection systems and an analogue computer to automatically integrate information from the Tracker's anti-submarine sensors. This was called the Anti-Submarine Warfare Tactical Navigation System  (ASWTNS) and is described in more detail elsewhere in this web document. The first CS2F-3 (#1552) conversion was completed on 18 July 1966 and the last CS2F-3 (#1555) was completed on 19 April 1968.

Marine Reconnaissance Version

When the carrier HMCS Bonaventure was paid off  in 1970, there was immediate shift from deep-water antisubmarine surveillance to shallow-water surveillance with some emphasis on sovereignty surveillance flying. By 1973, the Tracker's role had been transformed once again with a move to surveillance flights over waters of Canadian interest  and adjacent land areas.  At this time, the aircraft was completely relieved of its anti-submarine responsibilities and was given priority as a maritime patrol aircraft.

Another change occurred in 1977, when the Government of Canada formally ratified the United Nations Convention on the Law of the Sea (UNCLOS III), which mandated the creation of an Exclusive Economic Zone (EEZ) extending 200 nm off all coasts. This created a requirement for military enforcement of sovereignty to protect natural resources within the EEZ, such as oil and gas reserves, and fisheries.

Trackers were modified for this role and provided support for Fisheries and Oceans Canada, the government department responsible for managing Canada's ocean resources. These aircraft were used to patrol George's Bank and the Grand Banks and to monitor foreign fishing fleets. Search and Rescue (SAR) was a secondary role which was no less important to the civilian population of the Maritime Provinces which relied on SAR aircraft for urgent MEDEVAC to large tertiary-care hospitals in Halifax and Moncton as well as for mariners and air crew who frequently found themselves in distress, requiring rescue.

Between 1974 and 1981 a number of Trackers were either disposed of, or placed in storage, and of the twenty that remained, all were stripped of their ASW equipment and arrester gear and were converted for use in fisheries patrol duty, northern sovereignty patrols in support of the EEZ as well as secondary SAR  duties. New items included a high-powered radar along with a day/night photographic system. These gave the Tracker great flexibility as the Squadron operated in all kinds of weather and light conditions.  The "Codfish" computer was installed in the Tracker in 1986. It was capable of storing communications logs, photos, and holding current fisheries license lists. After conversion, the maritime reconnaissance version only had a single sonobuoy in each nacelle.

VS 880 squadron flew most of these aircraft with the remainder allocated to VU 32, VU 33 (at CFB Comox) and 420 Air Reserve (AR) Squadron at CFB Shearwater. The crew complement was reduced from to four to three, including two pilots and an Airborne Electronic Sensor Operator (AESOP). These aircraft were modified to carry either 6" x 36-inch rocket underwing pods for use in the sea surveillance role or a day/night photographic pod beneath the starboard wing for pollution detection and fishery patrol. Prompted by the budget cuts of 1989, these Trackers served until 1990 when the existing fleet of 18 aircraft was withdrawn from service. This decision had the immediate effect of  cutting the Canadian Forces maritime surveillance capability by  more than 50 percent. Some of the fisheries surveillance work was contracted to civilian companies.  Most roles performed by the Tracker were eventually taken over by the CP-140 Aurora and Arcturus follow-on aircraft.

In service from 1956 until 1989, the Tracker was one of the longest-serving piston aircraft in the Canadian Forces inventory. (Canadian Forces photo).

DESIGNATORS and SERIAL NUMBERS

Jeff Rankin-Lowe provides some background on the Tracker's designators and serial numbers:

Designators

The prototype for the CS2F-3 was 1558, but it was not redesignated. A total of 45 CS2F-2 Trackers were converted and redesignated as CS2F-3s. Along with the two CODs, a total of 44 Trackers were redesignated as CP-121's. All but the two CODs were CS2F-3's.

On 27 July 1970, official authorization was issued to redesignate the two CS2F-1 (COD) aircraft and the surviving CS2F-3 Trackers as CP-121's. Their reserialling to the 121xx range had occurred effective 11 June 1970.

"Mk" was not official, although it was used by some people.

"CP-121" was part of the RCAF's cumbersome dual designation system, which remained in effect until mid-1976. Under that system, "CP-121" was the CTS (Chief of Technical Services) Control Number, "CS2F" was the Type Designator, and "Tracker" was the Popular Name. I saw a memo in the files from the officer responsible for streamlining the designation system and he said it was his "life's work" to accomplish it. CFAO 36-37 went from nine pages all in English to two pages plus an annex, all of it bilingual. After that, CP-121 was the Designation and the Type Designator was dropped.

Serial Numbers

There were 99 DHC-built Trackers and their original RCN serials were 1502 to 1600. 1500 was the original serial for the one they assembled from components supplied by Grumman to test the jigs and tooling. It was later reserialled as 1501.

The c/n's (constructor's numbers, or manufacturer's serial numbers) are offset by one digit from the serials, e.g. 1502 is DH-01, 1550 is DH-49, and 1600 is DH-99.

Not all of the serials from 12101 to 12199 were used and since 1600 was out of service before the new serials took effect on 11 June 1970, it was never put in the 121xx range. However, several training aids at CFSATE were incorrectly painted with serials and included "121600" among others. They were never official.

After Armed Forces Unification, the plan for most types was to have serials starting with the three digits of the CTS Control Number, followed sequentially by 01, 02, 03, etc. That system would have only applied to surviving aircraft and not tied the old and new serials through the last two or three digits. It was instead decided to keep that link, probably so as to help eliminate mixing up maintenance and other records.

Only the CC-129 Dakota fleet was reserialled without any connection to their old serials, but that was because those old serials were a mix of RCAF (three, four, or five digits) and RAF-style serials (two-letters/three-digits). The CC-129s were reserialled from 12901 to 12971. The early 1968 plan was never adopted for the Tracker and the only 121xx serials were those assigned in 1970, which left gaps for all of the Trackers no longer in service.

SPECIFICATIONS

Length: 42 feet, 0 in.  [1]
Wingspan:  Without outboard UPD-501 antennae - Extended 69 ft 8 in. Folded 31 ft 8 in  [2]
                  With outboard UPD-501 antennae installed - Extended 72 ft 1 in. Folded 32 ft. 10.5 in. [2]
Height: 16 ft 3.5 in. [2]
Speed: 265 mph at sea level;  159 mph cruise patrol
Max ceiling: 22,000 ft.
Range: 1,000 nm (approximate) [4]
Endurance: 8 hours (approximate) [4]
Engines: Two Curtiss-Wright Cyclones (R1820-82WA) manufactured by Pratt and Whitney Canada under license as P&W model number 983C9HE1. This P&W  model number is what appears on the nameplate affixed to the engine. The Cyclones developed 1275 hp @2500rpm continuous.  Each engine could produce 1575 hp for up to five minutes. The P&W engines were modified to have the master rod in the number five cylinder instead of number one. The engineering spec indicates this modification improves reliability [3].
Propellor design: #6915E-7
Propellor Diameter: 11' 0"
Maximum gross weight: 18,750 lbs empty and  24,500 lbs  field take off weight. [2]
Fuel capacity: 433 gallons of 115-145 or 100-130 Avgas in six wing tanks. [2]
Oil capacity: 2 tanks of 10.25 gallons each. [2]
Carrier takeoff distance: slightly more than 300 feet.
Crew:  4 consisting of pilot, co-pilot, MAD operator and radar operator.
Armament: Two homing torpedoes or depth charges located in the bomb bay and six underwing
attachments for depth charges or rockets. These included different combinations of Mk. 41, 43, 34 anti-submarine homing torpedoes, Mk.54 depth charges and mines.
Armament hardware: Six Aero 14B Bomb racks. (Main plane)
                                 One Mk 51 Bomb rack (bomb bay)
                                 One Mk 8-0 Bomb shackle (bomb bay)
                                 Two practice Depth Charge Dispensers (Nacelles)
                                 1 Retro Ejector (Fuselage)
                                CRV-7 air to surface rocket. This would have been employed in an anti-shipping role had
                                 the need arisen.
Comment: In the Squadron/Signal publication on the Tracker (p. 21), it's stated that, " ... the Canadian Trackers, despite their similar designations, were not equivalents of U.S. Navy S2F-1, S2F-2 or S2F-3 aircraft."

	CS2F-1 key dimensions. Note that the wingspan dimension does not include the UPD-501 "can" antennas. Source:  RCN - Aircraft General Information Data" dated May 1, 1963.[2] (Provided by Leo Pettipas)
	CS2F-2 key dimensions. Note that the wingspan dimension includes the permanently attached UPD-501 "can" antennas. Source:  RCN - Aircraft General Information Data" dated May 1, 1963. [2] (Provided by Leo Pettipas)
	This is a three sheet extract from "RCN Aircraft General Information Data" from 1963. The data appearing in this PDF file was used extensively throughout this web page.  (Provided by Leo Pettipas)

Built by the restoration crew at the Canadian Warplane Heritage Museum, this is a mockup of a Mk43 Mod3 torpedo that was carried by the Tracker. (Photo by Jerry Proc)

PAINT SCHEMES

RCN ERA

There were three basic Tracker paint schemes:

(1) the RCN double-grey scheme (like the Avengers); then,
(2) an overall light grey; then
(3) an overall dark grey.

POST UNIFICATION ERA

Trackers post Unification were initially overall Grey #501-109 with colour Symmetrical Era markings, then changing to overall Grey FS.595 26173 starting around mid 1984 with Grey 26118 markings.

If anyone can provide non-copyrighted colour photos to illustrate the Tracker colour schemes, I will be happy to post them. Contact: jerry.proc@sympatico.ca

Tracker anti-submarine operations ceased at CFB Shearwater in the summer of 1981 but maritime reconnaissance soldiered on until 1990 when the last aircraft was finally stricken off strength on March 31. That was 34 years after the first flight of the Canadian-built CS2F-1.  Many of the retired aircraft have found civilian uses.

Maintaining the old Pratt & Whitney 983C9HE1 engines had become increasingly difficult, therefore "Turbo Tracker" conversions become popular. The engines of choice are the Garrett TPE331 or the Pratt & Whitney Canada (PWC) PT6A turboprop, both typically rated at 1,227 kW (1,645 SHP). Conversions have been performed by a number of companies such as Conair of British Columbia and Marsh Aviation of Arizona.

In 1988, there was a project undertaken between the Canadian Forces and IMP Aerospace of Halifax to re-engine the Trackers with Pratt & Whitney Canada PT6A-67 turboprop engines. However, just as the first Tracker was converted, the project was cancelled and the Trackers were retired from service.  Pictured above is a Conair Turbocat. The company, based at Abbotsford, British Columbia,  re-engined a number of piston engine Trackers with turboprop engines. All aircraft were sold to France. (Conair photo taken by Chester Goosen of F22 Photography)

This news story was sent out  October 8, 2012:

"A piece of aerial firefighting history has flown its last mission and will become the newest display at the Canadian Museum of Flight in Langley, British Columbia, about 30 miles east of Vancouver.

Conair Group Inc., which pioneered the conversion of military surplus aircraft into air tankers, is phasing out its fleet of Firecats, modified Grumman CS2F Tracker submarine hunters. It donated the airworthy aircraft to the museum. The twin-radial-engine aircraft were carrier-based patrol aircraft used by the Canadian and U.S. Navies in the 1960s. Conair converted more than 35 for use as firefighting aircraft.

The museum's new plane spent its operational history aboard the Canadian aircraft carrier HMCS Bonaventure. Conair raised the floor of the aircraft and installed an 867-gallon tank where the torpedo bay once was. The result was a relatively maneuverable and powerful air tanker suited to the mountainous terrain of B.C. and the western states.

Langley was a natural choice for preservation of the aircraft because it was the location of Conair's predecessor company Skyway Air Services, which pioneered aerial firefighting. Conair is now a major air tanker contractor and modifier based in Abbotsford, B.C., 20 miles east of Langley."
 

FOOTNOTES:

[1] The license-built CS2F was the same length as the U.S. Navy S2F-1, an even 42 feet (12.80 m).
This allowed the Canadian Trackers to fit aboard HMCS Bonaventure.  A subsequent variant for the U.S. Navy, the S2F-3, was lengthened 18 inches (14 inches from the front of the bomb bay and 4 inches aft) to provide more interior volume.

[2] The spec shown was derived from "RCN - Aircraft General Information Data" dated May 1, 1963. At least one -1 Tracker had the UPD-501 antennae installed, thus increasing the length of the wingspan. In the same breath, some -2 Trackers had their UPD-501 antennae removed thus shortening the wingspan.

[3] From the  ELD (Engineering Logistics Directive) for the Tracker circa 1988. An ELD is sort of a "state of the fleet" report and covers a wide range of information. The introduction says it's an "authoritative document...issued for the direction of all [CF] authorities involved in the production, introduction into service, utilization, support, repair, modification, phase-out, and disposal of the [aircraft]."

ELDs (usually) have two volumes. Part 1 is unclassified and is the main document, while part 2 is classified and details the "Concept of Operations".

[4] Quoted from Flight Comment Magazine, 1990 No 3. page 4.

[5] SERA was actually a harbinger of things to come in flight control design. All modern jet transports have rudder limiters to give sufficient rudder at low speeds but restricting rudder throw at high speeds to avoid over-stressing the structure. These began as mechanical stops, then moved to hydraulic limiters and now are part of the software  fly-by-wire systems incorporated in aircraft.

---

Credits and References:

1) Ernie Cable, Associate Air Force Historian. Shearwater Aviation Museum.  <erncar(at)ns.sympatico.ca>
2) Leo Pettipas <lpettip(at)mts.net> Associate Air Force Historian. Air Force Heritage and History 1 Canadian Air Division.
Winnipeg, Manitoba.
3) White paper "Early Cold War Anti-Submarine Warfare Development in Canada" by Leo Pettipas.
4) http://en.wikipedia.org/wiki/S-2_Tracker
5) http://www.vectorsite.net/avtraker.html
6) CP-121 photo http://www.airforce.forces.gc.ca/v2/equip/hst/tracker-eng.asp
7) Jeff Rankin-Lowe  <siriusproductions(at)sympatico.ca>
8) Jerry Vernon <jevernon(at)telus.net>
9) Shearwater Museum    http://www.shearwateraviationmuseum.ns.ca/exhibits/tracker.htm
10) Grumman CS2F/CP121 TRACKER ( RCN) by Colonel ( Ret'd) David H. Tate
11) http://home.wxs.nl/~roden171/operatorse.html
12) http://te-in.facebook.com/topic.php?uid=2235727114&topic=14322
13) Jim Van Dyk, Canadian Warplane Heritage   <jvandyk(at)warplane.com>
14) Patrick Martin <104655(at)telus.net>
15) Paul Cabot, .Manager Canadian Aerospace Museum, Toronto Ont.  <pcabot(at)casmuseum.org>
16) Tommy Thomason  <tommythomason(at)sbcglobal.net>
17) Robert Stitt <robstitt(at)brookhouse.bc.ca>
18) Peter Charlton . With quotes from his excellent book: Nobody Told Us It Couldn't Be Done -  The VX 10 Story.

Sept 5/14