The Conair Firecat is a fire-fighting aircraft developed in Canada in the 1970s by modifying military surplus aircraft. The modifications were developed by the maintenance arm of the Conair Group, now a separate company called Cascade Aerospace.
The Firecats are retrofitted Grumman S-2 Trackers. Conair bought a large number of Trackers formerly operated by the Canadian Navy and a small number of ex-United States Navy aircraft as well. The Trackers are modified for aerial firefighting as Firecats by raising the cabin floor by 20 cm (8 in) and fitting a 3,296 litre (870 U.S. gal) retardant tank where the torpedo bay is normally located. All superfluous military equipment is removed and the empty weight is almost 1,500 kg lower than a Trackers. The first aircraft was modified in 1978. Some examples have been re-engined with Pratt & Whitney Canada PT6A-67AF turboprop engines and are known as Turbo Firecats, these feature a larger tank and extra underwing fuel tanks; the Maximum Take Off Weight (MTOW) is increased by 680 kg (1,500 lb) to 12,480 kg (27,500 lb), while the lighter turbine engines also reduce the empty weight. The first Turbo Firecat was produced in 1988.
Conair commenced Firecat operations in 1978. The Sécurité Civile organisation in France took delivery of 14 Firecats over a period of five years commencing in May 1982. A total of 35 Firecat and Turbo Firecat conversions have been performed.
History of the Firecat
Grumman CSF Tracker in Canadian service
In 1954 the Royal Canadian Navy selected the Grumman S2F Tracker for anti-submarine search and attack to replace its Grumman Avengers. A large United States contract with Canadian manufacturers for Beech T-36 components had just been cancelled at the ending of the Korean war. This left some manufacturers short of work and so the decision was taken to place the order in Canada.
De Havilland of Canada was given the order, as prime contractor, initially for 25 aircraft, soon increased to 99. The RCN also ordered two S2F aircraft from Grumman. One, USN serial 136519, retained its USN serial and S2F standard, but the other, RCN 1500, was converted to CSF standard by using it for trial installations of Canadian equipment. Many components were subcontracted to spread the work. Major sub-contractors were: wing complete, Canadian Car & Foundry Co; rear fuselage, Canadair; tail section complete, Enamel & Heating, Amherst, Nova Scotia; engine nacelles, MacDonald Bros Aircraft, Winnipeg; undercarriage, wheels, brakes and shock struts, Jarry Hydraulics, Montreal; nose undercarriage, retracting struts, tail bumper, Dowty Equipment of Canada, Ajax, Ontario; honeycomb and sandwich components, Fleet Manufacturing, Fort Erie. The Wright R-1820-82 engines were built under licence by Canadian Pratt & Whitney Aircraft Ltd at Longueuil.
The Tracker, Grumman's type G89, was a twin-engined, high-wing monoplane with folding wings for carrier operation. A retractable magnetic anomaly detector (MAD) boom extended rearwards from the tail, and a retractable radome for an APS-38 search radar was fitted in the rear fuselage. A 70 mn candlepower searchlight could be carried under the starboard wing, 16 sonobuoys were housed in the nacelles, and Julie echo-sounding equipment with 30 charges and Jezebel long-range acoustic search equipment were fitted. It carried six Mk 43 torpedoes, two in the bomb bay and four under the wing.
The Canadian-built aircraft had some equipment installed to suit RCN requirements and were originally designated CSF-1s but, after trials with the first 43 aircraft, equipment changes resulted in the CSF-2. Structurally, the Canadian aircraft were identical to the US-built machines and were interchangeable in this respect.
The Canadian prototype, the second production aircraft, RCN 1503, was first flown at Downsview by George Neal and Anthony Verrico on 31 May, 1956. The first production aircraft, RCN 1502, was flown a week later, 6 June, by the same crew. Deliveries began in October. RCN 1501, which had been assembled from components supplied by Grumman to check DHC’s tooling, first flew on 8 January, 1957, piloted by George Neal.
The Trackers served with VS880 Squadron on HMCS Bonaventure and with VU32 and 33 Squadrons on shore bases. Apart from some problems with tail-hook failures, they served the RCN well. Seventeen Trackers were given to the Netherlands in November 1960.
To achieve low approach and manoeuvring speeds the Tracker has a generous flap area comprising over 80% of the wing trailing edge. This leaves room for only small ailerons that are augmented by 13 feet of perforated spoiler that arc upward from two slots in the upper side of the down-going wing during a turn. The wing also features a fixed leading edge slot near each tip, the whole combination giving the Tracker exceptional turning and low speed capabilities with a stall speed of only 70 knots with full flap at maximum landing weight.
Without the benefit of folding nose or tail structures, the Tracker was of necessity a short-coupled design with a large vertical empennage to provide adequate directional stability. However, even the generous fin and rudder combination could not provide sufficient directional control in the event of an engine failure. Grumman’s solution was the innovative Single Engine Rudder Assist (SERA), a two-sectional directional trimming and control surface attached to the vertical stabilizer.
The rearmost surface, with an additional servo tab, functioned as a normal mechanically-actuated rudder for cruise flight. The section closest to the fin had two purposes: a rudder trimmer driven by an electric screw jack for normal flight and a hydraulically-driven power assist system for the critical approach and take-off phases. With the SERA system selected, the rudder and rudder trimmer acted together to produce an impressive sweep of about 40° each side, enabling the Tracker to achieve a minimum control speed with one engine failed of only 85 kts. The rudder also features an unusual T-shaped trailing edge that effectively increases the width and therefore the effectiveness of the vertical control surface.
A further interesting control feature is the use of a spring link between the retractable tail bumper and the elevator control circuit. Lowering the undercarriage had the potential of creating a large forward shift in the centre of gravity, causing a marked nose-down trim change and effectively reducing the pitch control range. The spring device counteracted this undesirable characteristic by providing an automatic nose-up trim change without control input from the pilot, thereby maintaining full nose-up elevator travel.
Technical Details (Grumman Tracker)
Engines: Two 1,525 hp Wright R-1820-82 radials
Maximum speed: 287 kt (531.8 km/h)
Cruising speed: 130 kt (240.9 km/h)
Empty weight: 17,500lb (7,945 kg)
Loaded weight: 24,193lb (10,984 kg)
Span: 69 ft 8in (21.23 m)
Length: 42 ft 3 in (12.88 m)
Height: 16ft 3 ½ in (4.96 m)
Wing area: 485sqft (45.1 sq m)
Initial rate of climb: 1,920 ft/min (585 m/min)
(Sources: Canadian Aircraft Since 1909, Molson/Taylor; Air Enthusiast Jan/Feb 1996; Wikipedia)