Short C-23 Sherpa – Once a US Army Valuable Asset, Landing Where the C-130 Could Not

Short C-23 Sherpa can operate where a C-130 cannot land, while a CH-47 is too expensive to operate for a light load

Introduce

The box-shaped aircraft described by many as a “work horse”. According to Major Matthew Moore, chief of future operations with the Operational Support Airlift Agency, or OSAA: the C-23 can operate where a C-130 cannot land, while a CH-47 is too expensive to operate for a light load. C-23 was another tool that was cost-effective in homeland defense, disaster preparedness and the Global War on Terrorism.

Design

The C-23A was designed as a twin-engine turboprop strut-braced high-wing aircraft with an H-shaped tail assembly. The aircraft was built on the basis of a fuselage with a length of 17.7 m with a square cross section and characteristic nose and tail contours. A straight wing with a span of 22.76 m was used with developed mechanization, which simplifies takeoff and landing. The airframe was mainly made of aluminum with separate steel parts.

As a freighter, Sherpa was fitted with a full-width rear cargo door. Inside the fuselage, it was a cabin with 1.98 m (6.5 ft) wide, 1.98 m (6.5 ft) high and 8.84 m (29 ft) long. It offers a cargo volume of 34.83 m3 (1,230 cu ft), with a cargo capacity of 3,6 tons (8,000 lb).

An empty C-23 military vehicle weighed 6.5 tons, and the maximum take-off weight reached 10.4 tons. Landing on any runway with a mass of no more than 10.25 tons was allowed.

Powerplant

Short C-23 Sherpa is equipped in the center section of two Pratt & Whitney Canada PT6A-45-R turboprop engines with a capacity of 1200 hp each. The motors were equipped with Hartzell five-blade variable-pitch propellers with a diameter of 2.82 m.

Sherpa has a cruise speed of 350 km/h (220 mph), a maximum range of 1,239 km (770 mi) with a payload of 2.2 tonnes. The aircraft was operated by two pilots, the third crew member was responsible for handling cargo.

Capacity

The C-23B Sherpa aircraft is a light military transport aircraft, designed to operate efficiently, even under the most arduous conditions, in a wide range of mission configurations.

As a troop transport, the Sherpa provides comfortable, air-conditioned seating for 30 passengers. During airborne operations, the aircraft accommodates 27 paratroopers. Optionally, it can be outfitted to handle up to 18 stretchers plus 2 medical attendants.

Specifications

(Source: Wikipedia)

General characteristics

• Crew: 3 (2 pilots plus 1 cabin crew)
• Capacity: 30 passengers, or 18 Litter based passengers / 7,000 lb (3,175 kg) maximum payload
• Length: 58 ft 0.5 in (17.691 m)
• Wingspan: 74 ft 8 in (22.76 m)
• Height: 16 ft 3 in (4.95 m)
• Wing area: 453 sq ft (42.1 m²)
• Airfoil: root: NACA 63A418; tip: NACA 63A414
• Empty weight: 14,727 lb (6,680 kg) including crew
• Max takeoff weight: 22,900 lb (10,387 kg)
• Maximum landing weight: 22,600 lb (10,251 kg)
• Fuel capacity: 560 imp gal (670 US gal; 2,500 l) / 4,480 lb (2,032 kg)
• Powerplant: 2 × Pratt & Whitney Canada PT6A-45-R turboprop engines, 1,198 shp (893 kW) each
• Propellers: 5-bladed Hartzell, 9 ft 3 in (2.82 m) diameter constant-speed fully-feathering propeller

Performance

• Cruise speed: 190 kn (220 mph, 350 km/h) ::::157 kn (181 mph; 291 km/h) at 21,000 lb (9,525 kg) AUW at 10,000 ft (3,048 m)
• Stall speed: 73 kn (84 mph, 135 km/h) at MLW flaps and gear down

90 kn (104 mph; 167 km/h) flaps and gear up

• Range: 195 nmi (224 mi, 361 km) with 7,000 lb (3,175 kg) payload, max fuel, reserves for 45 minute hold and 43 nmi (49 mi; 80 km) diversion

669 nmi (770 mi; 1,239 km) with 5,000 lb (2,268 kg) payload, max fuel, reserves for 45 minute hold and 43 nmi (49 mi; 80 km) diversion

• Service ceiling: 12,900 ft (3,900 m) one engine inoioerative at 21,000 lb (9,525 kg) AUW
• Rate of climb: 1,180 ft/min (6.0 m/s)
• Wing loading: 50.55 lb/sq ft (246.8 kg/m²)
• Power/mass: 0.1046 shp/lb (0.1720 kW/kg) maximum
• Take-off run (FAR & BCAR Gp.A): 3,420 ft (1,042 m) ISA
• Take-off run (FAR & BCAR Gp.A): 3,420 ft (1,042 m) ISA +15 °C (59 °F)
• Landing run at MLW BCAR: 4,020 ft (1,225 m) normal field
• Landing run at MLW BCAR: 3,150 ft (960 m) short field
• Landing run at MLW FAR: 3,650 ft (1,113 m)