Saab 90 Scandia

Design and development

In late 1943, the design office of SAAB realised that the demand for military aircraft would be likely to considerably drop once the Second World War came to an end, and consultations were made with the Swedish airline AB Aerotransport to determine the airline's needs for new airliners. SAAB's board of directors decided to launch detailed design work on the new airliner, known initially as Projekt CT, in February 1944. The new airliner was intended to be a short to medium-range replacement for ABA's Douglas DC-3s. It was a low-winged, all-metal twin-engined aircraft and was planned to carry 25–30 passengers, with a range of about 1,000 kg (2,200 lb) and a take-off weight of about 11,600 kg (25,600 lb). Pratt & Whitney R-2000 Twin Wasp radial engines rated at 1,450 hp (1,080 kW) were chosen for the project, with the intention that the first prototype would fly in summer 1945.

Production of the prototype was delayed by industrial action in early 1945, and the desire to seek airworthiness certification under American rules to aid export sales. The project was publicly announced in December 1945, with the name SAAB 90 Scandia.

The prototype Saab 90 (Scandia) first flew in November 1946. It was capable of seating 24–32 passengers, with low-speed capability. It was to be fitted with Pratt & Whitney R-2000 engines. It had a single nosewheel and fully retractable landing gear. ABA Swedish Airlines, a predecessor of SAS, ordered 11 examples. The Type certificate was issued in June 1950. Delivery started in October 1950 but, after testing, specification had changed to the Pratt & Whitney R-2180-E Twin Wasp E. Two Brazilian airlines (VASP and Aerovias do Brasil) also ordered a total of six aircraft. The prototype was subsequently converted to a luxury private executive aircraft for the Brazilian industrialist Olavo Fontoura.

Design

The Scandia project was initiated in 1944 by a supposed need (after World War II) for an aircraft carrying 25–30 passengers for a distance of up to 1000 km.

Main design objectives were: safety; two engines; long life; economic operation.

The wing was shaped, using NACA profiles, to provide good stalling characteristics. Low wing design was chosen since it provided:

Less structural weight

Better safety in an emergency landing

Possibility for one continuous flap

The wing was built in three pieces. The centre section with engine mounts, and left and right sections which were bolted to the centre section, immediately outboard of the engine nacelles.

The fuselage diameter was chosen to allow for four seats per row. This configuration gave a capacity of 32 passengers. A configuration with wider and more comfortable seats, three seats per row, carrying a total of 24 passengers was also offered. The prototype (90.001) was equipped with 1,450 bhp (1,080 kW) Pratt & Whitney Twin Wasp R2000 engines (changed to 1,650 bhp (1,230 kW) P&W Twin Wasp R2180 on the production version).

The entire aircraft was built of metal except for the rudders which were fabric-covered metal frames.

Test flights

The prototype (SE-BCA) made its first flight on November 16, 1946. Claes Smith was the pilot. The first flight lasted for 20 minutes. The plane had exceptionally good slow-flying characteristics, with full control down to 110–115 km/h. The stall was slow and preceded by vibrations. The plane also turned out to be easily maneuvered with one engine shut down, which at the time was typically not the case with twin-engined aircraft. Unfortunately the rudder harmony was not satisfactory, with high control forces in some situations. The engine installation also needed redesign.

The prototype flew a total of 154 hours before the winter of 1947/48 when it was parked in the hangar for modifications. The engines were elevated for increased clearance between propeller blades and ground. The cabin, which previously contained only test equipment, was furnished. On February 7, 1948, the prototype took off again and began the second testing phase. The second phase consisted of mainly performance tests. After 700 hours of test flying it was decided to introduce the following changes to the production planes:

More powerful engines

Four-blade Hamilton-Standard propellers

Spring tabs on rudder and elevators for reduced control forces

Operational history

The first production Scandias were delivered in 1950. SAS received its eight aircraft between October 1950 and October 1954. SAS initially operated its Scandias on intra-Scandinavian flights. Scheduled services by Scandias were operated also to European cities including Amsterdam, Brussels and London Airport (Heathrow) between 1951 and 1955. Until Scandias were withdrawn in 1957 they also served in a modest first class configuration on the new route from Scandinavia to Moscow via Riga.

VASP operated its fleet of new and ex-SAS Scandias on intra-Brazilian scheduled flights between October 1950 and late 1966.

The Swedish Air Force put heavy and insistent demands upon the SAAB factory, for the Saab 29 fighter aircraft, which spelled the end of the Scandia project in Sweden, with residual production being undertaken by Fokker, in the Netherlands.