Palas Conversion

1952 civilian conversion.

Unknown number of C-46A, C-46D, C-46E and C-46F converted.

This conversion was designed to improve the Commando's hot & high takeoff performance. It was originally designed at the request of Lloyd Aereo Colombiano, which operated its Commandos out of Bogota, Colombia, elevation 8,200 feet. L.B. Smith Aircraft Corporation was approached, and designed the conversion by adding two Turbomeca Palas engines, mounted in underwing nacelles designed by French SNCASO. This was the first time an installation of this type has been made for passenger service by a US company. VARIG later purchased the Palas conversion for several of its own Commandos.

The Turbomeca Palas was a small single-spool turbojet designed by French engine manufacturer Turbomeca, weighing 72 kg while offering 350 lbs of thrust. Its construction was simple, with a single-stage centrifugal compressor, an annular combustion chamber, and a single-stage turbine. The turbojets' inlets were originally flat, but were later redesigned as flush intakes to prevent the compressor from windmilling in flight.

The first Palas-equipped Commando, with two units mounted under the fuselage, flew in October 1952. On later designs, the Palas were mounted underwing. Most Palas conversions were short-lived, with the turbojets eventually removed from the airframe.

Below: a view of the first Palas conversion prototype with underwing engines in 1952.
Bottom left & center: the early Palas nacelles with panels removed in 1952.
Bottom right: the new nacelles with flush intakes redesigned by SNCASO in 1955.
Photo credit: Flight, November 1952 & Aviation Week, 19 December 1955

• Curtiss C-46A-45-CU Commando: PP-VBY (underwing, 1952),  PP-VCE (underwing, mid-1950's), PP-VCF (underwing, 1953), PP-VCG (underwing)
• Curtiss C-46D-10-CU Commando: HK-390 (underwing, 1953)
• Other Commandos: two other Lloyd Aereo Colombiano Commandos