Smith CW-20T Commando

1956 civilian conversion.

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

In the 1950's, several restrictions started to be placed by the CAA on the operation of aircraft holding only a military transport certificate for civilian transport duties. Several civilian conversions for the Commando were designed, offering not only a compliance with civilian aircraft design regulations, but also major performance enhancements.

In 1954, two Miami, FL firms, L. B. Smith Aircraft Corporation and Air Carrier Engineering Services, purchased a C-46F, applied several design modifications to it, and came up with the CW-20T civilian conversion - not to be confused with the original Commando prototype of 1939, designated by Curtiss as the CW-20T as well. After 9 months of flight testing, CAA approval for the supplemental type certificate was obtained in April 1956.

The CW-20T conversion encompassed approximately 30 modifications to the original Commando, including:

• The replacement of the old B-series R-2800-51 or -75 engines by the enhanced C-series R-2800, featuring several major design improvements. Horsepower was ramped up from 2,000 to 2,400 per side. A Convair-type oil cooler was also fitted to each engine, and its large size just beneath each engine required the cowl flaps to be relocated from the bottom to the top of the engine nacelles. The carburetor intake duct, directly above the engine, was also enlarged.
• A new stainless steel firewall, completely separating the power and accessory section of each engine. A stainless steel cowling was also installed around the engine accessories.
• A new fire-extinguishing system for the engine accessories and the wheel wells.
• A redesigned emergency fuel system.
• A strengthened undercarriage for both the main and tail wheels. DC6-type main wheels were also fitted.
• More powerful brakes.
• Alterations to the tail surfaces.

The resulting performance increases and operational improvements were as follows:

• Maximum takeoff weight increased from 45,000 to 47,650 lbs.
• Passenger capacity increased from 40 (or 44) to 55 seats.
• Cruising speed of 195 knots at 10,000 ft and 240 knots at 16,000 ft.
• Maximum endurance of 7.3 hours with 400 USGal of fuel.
• Maximum range of 1,420 NM with 400 USGal of fuel.
• Time to climb to 10,000 ft of 9 minutes.
• Service ceiling of 26,000 ft.
• Single-engine service ceiling of 10,200 ft.

Below: the traditional Commando engine cowl on the left, and the modified CW-20T engine cowl on the right. Note the position of the cowl flaps, the larger carburetor (top) and oil cooler (bottom) intake ducts.
Photo credit: Flight Magazine, 4 May 1956

Converted in Miami, FL by L. B. Smith Aircraft Corporation:

• Curtiss C-46A-5-CK Commando: N4215A
• Curtiss C-46A-50-CU Commando: N2085A
• Curtiss C-46A-55-CK Commando: N7864B
• Curtiss C-46A-60-CK Commando: N1381N, N2053A
• Curtiss C-46D-10-CU Commando: N9588Z
• Curtiss R5C-1 Commando:  N711Q, N4093A, N4164A, N4165A

Converted at Bordeaux Merignac, France by SFERMA:

• Curtiss C-46A-41-CU Commando: F-OBKA

Converted in unknown places:

• Curtiss R5C-1 Commando: LV-PMB
• Curtiss C-46A-41-CU Commando: N408K