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C-56/ C-57 / C-59 / C-60 / C-66 - Lockheed Model 18 Lodestar

There were quite a number of warplanes based on the Clarence Kelly Johnson-designed Lockheed Electra and the later Model 18 Lodestar. The C-60 is a twin-engine transport based on the Lockheed Model 18 Lodestar, the Lockheed equivalent of the DC-3.Lockheed 10/14/18 were twin-engine monoplanes - the L 10 (Electra) carrying 10 passengers at 200 mph in 1934; the 14 (Super Electra) carried 12 passengers at 240 mph in 1937; the 18 (Lodestar) carried 14 passengers at 225 mph in 1939.

During World War II, the Army Air Forces used the L-18 aircraft for training and for transporting personnel and freight. These aircraft received different numerical designations depending on engine type.

The Model 18 was developed because of problems with its predecessor, the Model 14 Super Electra (designated PBO and R4O in USN service). The first commercial operator of the Model 14 was Northwest Airlines which purchased eleven aircraft. Three of these aircraft crashed between May 1938 and January 1939 causing the flying public to lose confidence in the aircraft and Northwest returned the Model 14s to Lockheed and purchased the slower Douglas DC-3 (R4D in USN service) in March 1939. During the same period, five Model 14s crashed outside the U.S., one each in Canada, England and the Netherlands and two in Romania. Recognizing that it had a big problem, Lockheed began work on a replacement for the Model 14.

The Lodestar was similar in layout to most Lockheed transport aircraft of the inter-war years. It had low mounted tapered wings, with a moderate dihedral. The fuselage had flat sides, and a rather more pointed nose than earlier models. It had a high mounted tail, with twin vertical control surfaces at the ends. The standard version had a row of small cockpit windows on both sides, and a cabin door towards the rear of the left side of the aircraft.

The new aircraft used the wings, engines and tail surfaces of the Model 14 with a redesigned, stretched fuselage. Although very similar to the Model 14, a new model number, 18, was assigned and the aircraft was given the name Lodestar to distance it from the previous Electra family. The tailplane sits high on the fuselage. This is the result of research on the prototype, which disclosed a condition of vibration in the tail due to interference of the slipstream and the tailplane. This was completely cured by raising the tailplane about one foot. The longer fuselage caused an aerodynamic problem in that the changed airflow caused the elevators to nibble - i.e. oscillate back and forth in flight and after trials, raising the tailplane and adding a trailing edge extension to the inner wing solved the problem. But the stretched fuselage improved directional stability and allowed two more rows of seats in the aircraft thereby solving another problem of the Model 14, i.e., high seat-mile cost.

The resulting aircraft was a twin-engined, all-metal, twin-tailed, mid-wing monoplane with the main landing gear retracting into the engine nacelles. The tail wheel did not retract. As with the Model 14, the aircraft was equipped with leading-edge slots and Fowler flaps. The trend of aircraft design is seen in the high wing loadings of 31.76 and 33.5 lb./sq. ft. for the two loaded weights. To retain the moderate landing speed of 65 mph is only possible with the very efficient Fowler flaps.

The Lockheed Model 18 Lodestar first flew in September 1939 [1940?], the Model 18 was originally designed as a successor to the Lockheed Model 14 and the earlier Model 10 Electra. The Army began ordering military versions of the Model 18 in May 1941. The Lodestar was offered with the Pratt & Whitney Hornet, Twin Wasp or Wright Cyclone engines and with various interior configurations. Depending upon engines and interior configuration, these transports were given C-56, C-57, C-59, C-60 or C-66 basic type designations.

The Lockheed Model 14 Super Electra, and the Model 18 Lodestar proved to be extremely capable planes with among the best cruising speeds, ranges and altitude performance, besting that of its rival, the Douglas DC-3. The U.S. Congress passed the Civil Aeronautics Act of 1938, which created the Civil Aeronautics Board, and in March 1939, National Airlines was issued its original certificate of convenience and necessity authorizing the carriage of mail, passengers, and property over its system. The airline received the first of its 14-passenger Lockheed Lodestars in November 1940. During its delivery the plane set a transcontinental record of 9 hours and 29 minutes, which held for more than 15 years.

Converted from a Super Electra, it differed primarily by having the fuselage lengthened by 1.68m to provide accommodation for 15 to 18 passengers, depending upon the other facilities provided; some were produced with high-density bench seating for a maximum of 26 passengers, and were available with a variety of engines by Pratt & Whitney and Wright. Despite the improved economy demonstrated by the Lodestar, Lockheed failed again to achieve worthwhile sales in the United States as most operators were committed to purchase DC-3s from the Douglas Company. Fortunately, the type appealed more to export customers, with airlines or government agencies in Africa, Brazil, Canada, France, the Netherlands, Norway, South Africa, the UK and Venezuela ordering a total of 96 aircraft.

Interest of US military to "Lodestar" manifested itself for the first time in 1940, when the US Navy ordered one XR5O-1 and two R5O-1. Similar aircraft were delivered to the US Coast Guard. They were equipped with Wright R-1870 engines. 12 R5O-4, 41 R5O-5 and 35 R5O-6 were built. The first two options were, respectively, a 4-7-seat administrative and 12-14-passenger passenger transport aircraft. The third option was an 18-seat military transport aircraft used by the Marine Corps for parachuting operations. Equipped with engines Pratt & Whitney R-1830, one R5O-2 and three R5O-3 were built for the US Navy.

The US Army Air Corps ordered one aircraft with Wright R-1820-29 engines in May 1941 under the designation C-56 . It was a military version of the Civil Model 18-50. After some time, three aircraft were ordered Model 18-14 with engines Pratt & Whitney R-1830-53. In addition, orders for seven and three cars were made. Accordingly, all 13 vehicles were designated as C-57. The requisitioned civilian aircraft received the designation C-57A, seven military transport aircraft were known as the C-57B, and three of the latest C-60A aircraft were converted to Pratt & Whitney R-1830-43 star engines and designated C-57C. One of these three aircraft was the C-57D, later equipped with with engines R-1830-92.

In late 1941, when America entered the war, all "Lodestars" flying with the United States military were former airliners conscripted into service. These aircraft received different numerical designations depending on engine type. Most of the aircraft were removed from the US domestic service by December 1941, when they received a designation of a series of C-56: respectively, one C-56A, 13C-56B, 12C-56C, seven C-56D and two C-56E. A total of 10 Model 18-07 and 15 Model 18-56 were designated respectively C-59 and C-60.

In mid-1942, Lockheed introduced the C-60 variant of the "Lodestar". Designed specifically for military use, the C-60 was used as a troop and cargo carrier, flew anti-submarine patrols, and performed Search and Rescue duties. A total of 21 more C-60 and 325 C-60A were delivered. One of the last was the C-60B with an experimental de-icing system with hot air. The only aircraft model 18-10 with engines R-1830-53 with a power of 1200 hp. (895 kW) and 11 passenger seats was purchased in 1942 under the designation C-66 as VIP transport for the president of Brazil.

Lockheed built more C-60As for the AAF (325) than any other version of the military Lodestar. Soon after war began, the need for air evacuation was met by the peacetime practice of using regular transports. The first occasion requiring the movement by air of large numbers of patients occurred in January 1942 during construction of the Alcan Highway to Alaska. The second occurred in Burma in April 1942. In both instances regular transport planes (C-47s) already equipped with litter brackets were pressed into ambulance service.

Expressing irritation with failure to equip transport planes with litter supports, the AAF Directorate of Military Requirements called upon the Materiel Command for a report. In reply that Command summarized the situation. All C-47s were completely equipped with litter supports during production. While a shortage of critical materials had prevented installation in the first twenty-four C-46s delivered, all others would come equipped. Beginning in December 1942, all C-53s would be provided with litter brackets by manufacturers. Meanwhile, the Air Forces would install them in 200 planes of that type already delivered. Beginning in January 1943, supports for ten litters would be placed in each C-60. Finally, all new types of transports would be equipped with litter supports when deliveries began.

After the war, many military Lodestars were declared surplus and sold to private operators for use as cargo or executive transports. In 1957, the first fire jump for the California Smokejumpers was made out of a Lockheed Lodestar. The Lockheed Lodestar was powered by two 9-cylinder radial air-cooled engines providing a top cruise speed of 207 knots and a range of 1650 miles. Originally designed for commercial flights, the Lodestar was frequently flown by the Air Force in the 1940s. After the war, the Lodestar returned to civilian service and eventually found its way in to the Smokejumper program.

In response to an escalating number of transport aircraft crashes in the mid-1940s, in the 1950s researchers at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory undertook a decade-long investigation into a number of issues surrounding low-altitude aircraft crashes. The tests were conducted at the Ravenna Arsenal, approximately 60 miles south of the Lewis laboratory in Cleveland, Ohio. The aircraft were excess military transports from World War II. The nine-crash initial phase of testing used Lockheed C-56 Lodestar and C-82 transport aircraft to identify potential ignition sources and analyze the spread of flammable materials.

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