The Curtiss (or Curtiss-Wright) C-46 Commando was the largest two-engine cargo plane in the USAAF fleet. Its civilian incarnation, the CW-20E saw service up into the early years of the jet age. The plane was the subject of Design Analysis articles in the August, 1943 number of Aviation and the March, 1945 issue of Industrial Aviation.
A foldout color illustration (the same one missing from my copy of Industrial Aviation) in the June, 1945 issue of Flying provided the source for the wallpapers provided here.
The March, 1940, issue of Aviation included a large section (articles and ads) dedicated to the introduction of the CW-20 Curtiss-Wright Substratosphere Transport, featuring an "Engineering Close-Up" article. [ HTML ]. This was followed up with an article on the Design For Maintenance principles in the CW-20, "Maintenance at a Profit" [ HTML ]. Since the CW-20 was introduced before US entry into the war, it got a fair amount of press, being one of the largest two-engined planes yet produced.
An early Design Analysis article draft of the Aviation [ PDF, 17.2 MiB ] , [ HTML ] includes some supplementary material detailing some of the changes made when converting military C-46 airframes to CW-20E configuration for civilian use.
The Design Analysis article in Industrial Aviation [ HTML ] describes the CW-20E, the civilian version of the C-46. When the last contracts were let, the C-46 was up to -G revision. It can be assumed that all of the pertinent changes would have been incorporated into the CW-20E. The first delivered C-46s were C-46A revision level.
The CW-20 was envisioned as an efficient, large-capacity high-altitude transport, with pressurized fuselage. For much of its life it was the largest and heaviest operational two-engined landplane. The prototype featured a twin-tail empennage, which was subsequently changed to a more modern single fin. The cockpit was originally designed with glazing flush to a streamlined fuselage profile, reminiscent of the Boeing Stratoliner, but this was changed to a design with stepped windscreen, more similar to the Douglas DC-3. These changes lead to a substantial visual difference between the earliest and later models of the plane. The prototype was assigned the designation C-55 during some of its development.
Apart from the Design Analysis articles, the C-46 didn't get a lot of coverage in the magazines in my collection. In late 1944, Curtiss started an advertising campaign for their civilian adaptation of the airframe, the CW-20E.
- "Flight Test of the Curtiss-Wright Transport" [ HTML ] describes much of the initial flight test of the CW-20 Curtiss-Wright Substratosphere Transport.
- "Curtiss-Wright Presents Postwar Transport" [ HTML ] announces the CW-20E.
- "Commercial Commando" [ HTML ] also announces the CW-20E and appears to have been written based on the same press package.
The announcement articles and Jane's from the period all list the Wright Cyclone C18-B2 as the engine, which would have been an upgrade from the Pratt & Whitney Double Wasp, but the teething problems the
C18-B2 had in the B-29 and B-32, along with the fact that the P&W engines were prioritized to the bombers seem to have prevented that development.
- "Aviation's Sketchbook of Design Detail"
- A full-page Curtiss-Wright ad, "Introducing the new 36-passenger Curtiss-Wright transport" features a photo of the prototype on the ground, seen from 1 o'clock.
- "Presenting the Curtiss-Wright Transport," the introductory page to the special section on the CW-20, includes a photo of the prototype CW-20 on the ground, seen from 1 o'clock.
- "An Engineer's Close-up of the Curtiss-Wright Transport" [ HTML ] includes 6 photos and 4 drawings of details of the new CW-20:
- Cutaway drawing of CW-20 prototype [ drawing ]
- "The window panes are of transparent plastic, recessed to be flush with the external skin of the fuselage, and presenting a clean aerodynamic surface with no protruberances into the air stream. The panes are also curved to conform with the curvature of the fuselage, presenting a clean appearance. Each pane is secured in position by means of an external rim, which is flush with the outside fuselage skin and fits into a machined-out notch on the circumference of the outer face of the pane. (See insert) The rims are fastened to inner retainers by countersunk, flat-head machine screws fastened into self-locking gang channel nuts riveted to the inner retainer around the window frame, the panes being clamped tightly between the outer rims and the inner retainers. The windows are so proportioned that the inner retainers are directly fastened to convenient fuselage stringers and rings.
The windows are sealed around the edges by a rubber-cork sealing tape, the seal being made between the window pane and the outer rims and inner retainers respectively. The sealing tape is held in place by means of a sealing cement, providing water- and air-tight joint, yet allowing the pane to expand and contract freely with changes in temperature. Below the window is a shelf." [ photo ],[ drawing ]
- "The Curtiss-Wright cowl used differs from the NACA cowl (top) by allowing the cooling air to be expelled at the bottom only. This permits a smooth uninterrupted air flow over the top of the wing which is spoiled by the louvers in the NACA cowl." [ drawing ]
- "Connection of the wing center section to the fuselage is made by means of four wing attachment fittings in the fuselag mounted between reinforce fuselage rings, two at the front spar of the center section and two at the rear spar. The attachment of the wing to the fittings, and of the fittings to the rings, being made in such manner that the fitting is loaded as a simple beam (above)." [ photo ]
- "The flap arrangement operate first as a slot when moved rearward from the closed position (Figure 1 to Figure 2, left to right). From this position the flap moves rearward and downward (Figure 3 and Figure 4), operating over a range of 60°. Hydraulically operated by main piston located in the center section, the flap mechanism is motivated by a cable and pushrod system." [ photo ]
- "The landing gear when retracted is completely enclosed in the cowl. The lines of the cowl are uninterupted when the doors, which open outward from the center, are closed. For the first time the new Wright R-2600 engines are used developing 1700 total horsepower each. These engines are mounted with the dynamic engine mount suspension which reduces the engine vibrations that would otherwise be felt in the cabin." [ photo ]
- "The fuel tanks are supported at but five points, the first and fourth ribs in the photograph. This minimises bending and torsional loads imposed on the tank by movements of the wing." [ photo ]
- "One of the main features of the design of the transport is the smooth lines of the fuselage, greatly reducing the drag. The pilot's cabin winndows are faired in with the contour of the nose and the glass is flush with the skin as in the passenger cabin. The de-icers along the wing are also built so as to be flush with the skin and run outboard on the wings from the nacelles (not attached in the photograph). Notice the accessibility to the under part of the ship from the ground without the aid of ladders." [ photo ]
- "Maintenance at a Profit" [ HTML ] includes 3 photos and a drawing:
- "Battery compartments on each side of fuselage are easily accessible from the ground." [ photo ]
- "Closeup of one of the two 1700-hp Wright Double Row Cyclones showing unusual cowling. Propeller is Curtiss electric controllable-pitch, full-feathering type." [ photo ]
- "Engine cowling in position, showing air scoop at fully opened position. Landing gear doors close completely to form smooth surface." [ photo ]
- "Expanded view of powerplant section. Entire section forward of firewall may be detached by removing four bolts." [ photo ]
- A Cuno Engineering Corp (CUNO filters) ad, "Curtiss-Wright keeps pace with major advances in safer flying," shows the lefthand nose of the prototype CW-20.
- A Röhm & Haas Co (Plexiglas) ad, "Plexiglas on transports and trainers," includes a detail photo of the nose of the prototype CW-20 under construction (panels held on with Cleco fasteners.) The plane tried using a Plexiglas panel in the nose to shield the RDF loop.
- A United States Steel, American Steel and Wire (control cables) ad, "New Sub-stratosphere Transport Controlled with American Tiger Brand Aircraft Strand and Cords," shows the prototype CW-20 on the ground, seen from 11 o'clock, and a detail photo of a cable gallery, probably below the cockpit.
- A Cleveland Pneumatic Tool Co (Aerol shock-absorbing oleo-pneumatic struts) ad, "Two of Aviation's Greatest Achievements both equipped with Aerol struts," features photos of a P-39, seen from 3 o'clock on the ground, and a Curtiss-Wright CW-20 transport.
- "Flight Test of the Curtiss-Wright Transport" [ HTML ] includes a photo of the prototype CW-20 in flight, seen from 11 o'clock high.
- A Wright Aeronautical Corp (Wright aircraft engines) ad, "Curtiss-Wright Transport America's largest twin-engined airliner lists "36 passengers, 5200 lb cargo, 1500-mi range, over 240 mph, with 2 Double-Row Cyclone 14 engines." Ad includes a photo of the prototype CW-20 (NX19436) in flight, seen from 11 o'clock high.
- A Curtiss Electric Propellers ad, "15-Ft Curtiss Electrics equip America's largest twin-engined airliner," shows the prototype CW-20 on a field, seen from in front of the righthand wing tip.
- "Aviation's Sketchbook of Design Detail" for November, 1940, includes a drawing of one of four sections of the CW-20 flaps.
- Aviation's "Aviation Manufacturing" column for December, 1940, includes a photo of the modified CW-20 (single-tail modification) on final approach, seen from 4 o'clock with flaps and gear down.
- The "Have You Seen?" section for January, 1941, shows two versions of the CW-20 the original twin-tail and the revised single-tail models.
- A color Gallery photo, "Curtiss C-46," shows C-46A-CU 15159 in flight, seen from 10 o'clock. Plane has "meatball" insignia, OD paint scheme.
- Drawings from the Design Analysis articles:
- floor plan and profile of the CW-20E fuselage
- plan, profile and 4 cross-sections of the CW-20E fuselage