Photograph:
Radial Engine Air Tractor AT-401 VH-ODS (c/n 401-0695) at Caloundra, QLD (David C Eyre)
Country of origin:
United States of America
Description:
Single seat agricultural monoplane
Power Plant:
One 448 kw (600 hp) Pratt & Whitney R-1340 nine-cylinder air-cooled radial engine
Specifications:
-
- Wingspan: 14.97 m (49 ft 1¼ in)
- Length: 8.23 m (27 ft)
- Height: 2.59 m (8 ft 6 in)
- Wing area: 27.31 m² (294 sq ft)
- Max cruising speed at sea level: 251 km/h (156 mph)
- Cruising speed at 1,220 m (4,000 ft): 230 km/h (143 mph)
- Stalling speed flaps up: 118 km/h (73 mph)
- Stalling speed flaps down: 99 km/h (61 mph)
- Max rate of climb at sea level: 335 m/min (1,100 ft/min)
- Take-off run: 402 m (1,318 ft)
- Range at economical cruising speed at 2,440 m (8,000 ft) no reserves: 1,014 km (630 miles)
- Fuel capacity: 477 litres (105 Imp gals)
- Empty weight with spray equipment installed: 1,875 kg (4,135 lb)
<
- strong>Useful load: 1,690 kg (3,725 lb)
- Loaded weight: 3,565 kg (7,860 lb)
History:f
The AT-401 series was a development of the piston-engined AT-301 series and was the smallest of the Air Tracgtor series. The AT-401 was powered by the Pratt & Whitney R-1340 radial engine which was re-manufactured with a new Air Tractor crankshaft, new pistons, new main and thrust bearings, and a selected camshaft, driving a Hamilton Standard propeller, but optional propellers included models produced by Pacific Propeller. Th e AT-401 series incorporated the rugged durability, safety features and flying ease of the earlier series but with the lower price of a model powered by a piston engine.
In 1986 Air Tractor commenced work on improving the AT-300 and AT-400 series, and this involved the re-design of the wing, the span being increased by 1.22 m (4 ft), and being fitted with steel spar caps and reinforced leading-edges. A larger 1,514 litre (333 Imp gal) hopper was standard, and the elevators were metal rather than fabric covered. The prototype AT-401 (N8888S) was first flown in December 1986.
A variant known as the AT-401A (N1014L – c/n 401A-0733) was first flown in October 1989 and was powered by a 442 kw (592 shp) PZL R3S radial engine but this model was abandoned and this aircraft was later converted back to R-1340 configuration. Later an AT-401A was fitted with a 448 kw (600 hp) Orenda OE-600 eight-cylinder diesel engine.
The AT-401 has been produced through a number of models, the latest being the AT-401B which could be fitted with a heavier undercarriage for higher operating weights. Some AT-401s have been re-engined with turbines, including VH-SOW.
Construction of the wing wass two-spar of 2024-T3 light alloy with alloy steel lower spar cap, bonded doubler inside the wing leading-edge to resist impact damage, fibreglass wingroot fairings, and metal covering. Flaps and ailerons were of light alloy. The fuselage was of 4130N tube steel oiled internally, the skin panels being of light alloy. It had a non retractable spring-steel undercarriage. The cockpit seated one and was enclosed. A baggage compartment was placed in the bottom of the fuselage aft of the cabin with a door on the port side.
Examples of the AT-401 series appearing on the Australian Cibil Register have included: Model AT-401 VH-ODK (c/n 401-0689) delivered in 1988, followed by Model AT-401 VH-SNF³ (c/n 401-0955) in October 1994, which was converted to Model AT-402 configuration in 1998; Model AT-401 VH-SNB² (c/n 401-0877); and Model AT-401B VH-DDW (c/n 401B-0991).