During World War II, the U.S. Navy (USN) acquired 68 Lockheed Model 18 Lodestar transports for its use and for use by the U.S. Coast Guard (USCG) and U.S. Marine Corps (USMC). In USN service, the Model 18 Lodestar was designated R5O. Delivered between May 1940 and October 1943, the last R5O was struck off the inventory in June 1950.

The Model 18 was developed because of problems with its predecessor, the Model 14 Super Electra (designated PBO and R4O, q.v., 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, q.v., 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 Rumania.) Recognizing that it had a big problem, Lockheed began work on a replacement for the Model 14.

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 distant it from the previous Electra family. 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. Seven models of the aircraft were manufactured, the difference being the specific Pratt & Whitney or Wright engine that powered the machine. The specific engines were identified by a two numeric suffix to the model number, e.g., Model 18-07s were equipped with two Pratt & Whitney Hornet S1E2-G engines. The Model 18s could accommodate either 15- or 18-passengers depending on whether or not a flight attendant and full galley were provided.

The Model 18 prototype was actually one of the Model 14 Super Electras that Northwest Airlines had returned to Lockheed. With a new fuselage, this modified aircraft made it first flight on 21 September 1939. Two other Model 14s were also modified before the first production Lodestar made its maiden flight on 2 February 1940 and received an Approved Type Certificate (ATC) on 30 March 1940. The first airline to operate the Model 18 was Mid-Continent Airlines of Kansas City, Missouri which began service in March 1940 as soon as the ATC was awarded.  Mid-Continent eventually purchased four aircraft. Other U.S. airlines purchasing the aircraft included Continental Airlines (5), Dixie Airlines (2), Inland Airlines (1), National Airlines (3), Pan American World Airways (17, all to Pan Am subsidiaries, i.e., 2 to Pacific Alaska Airways and 15 to Panair do Brasil) and United Airlines (4). Overseas operators included the governments of South Africa (1), Norway (3) and the Netherlands East Indies (29); overseas airlines included Air Afrique (5) of Mozambique; Air France (3); British Overseas Airways Corporation (BOAC) (9); Venezuelas Linea Aeropostal Venezolana (LAV) (1); Brazils Navegacao Aerea Brasileira (2), South African Airways (21); and Canada=92s  Trans Canada Airlines (12) and Yukon Southern Airways (2).

The U.S. began a buildup of its military forces in 1940-41 and both the U.S. Army Air Forces (USAAF) and USN impressed a number of Model 18s for their use. These impressed aircraft were (1) being operated by U.S. airlines, (2) were being built by Lockheed or (3) had been ordered by the airlines but production had not started. The USNs impressed aircraft are described below; the USAAF impressed 102 aircraft designating them C-56, C-57, C-59 and C-60. Most of these impressed aircraft were returned to their owners or sold by 1944. The first true military aircraft was the C-60A ordered by the USAAF on 5 February 1942 as an 18-seat paratroop transport; the 324 C-60As consisted of 52 C-60A-LOs, 45 C-60A-1-LOs and 227 C-60A-5-LOs. Lodestars also served with the Netherlands East Indies Air Force, Royal Air Force, Royal Australian Air Force, Royal Canadian Air Force, Royal New Zealand Air Force and South African Air Force.

PRODUCTION HISTORY

XR5O-1: One Model 18-40 ordered for the USCG powered by two 1,200 hp (895 kW) Wright R-1820-40 nine-cylinder, single-row, air-cooled radial engines.

R5O-1: Three Model 18-40s powered by two 1,200 (895 kW) Wright R-1820-97 nine-cylinder, single-row, air-cooled radial engines; two aircraft went to the USN and one to the USCG in May 1940. At least one aircraft was transferred to the USMC in 1943.

R5O-2: One Model 18-07 powered by two 850 hp (634 kW) Pratt & Whitney R-1690-25 nine-cylinder, single-row, air-cooled radial engines.

R5O-3: Two Model 18-10s powered by two 1,200 hp (895 kW) Pratt & Whitney R-1830-34A fourteen-cylinder, twin-row, air-cooled radial engines; these aircraft were later equipped with R-1830-92 engines. These were VIP transports with luxurious interiors and accommodations for four passengers; later, they were modified with a more spartan interior.

R5O-4: Twelve Model 18-56s commercial airliners impressed by the USN and powered by two 1,200 hp (895 kW) Wright R-1820-40 nine-cylinder, single-row, air-cooled radial engines. These were staff transports with seven-seats. Four were transferred to the USCG in 1942 and at least one went to the USMC in 1942..

R5O-5: Fourteen Model 18-56s commercial airliners impressed by the USN and powered by two 1,200 hp (895 kW) Wright R-1820-40 nine-cylinder, single-row, air-cooled radial engines. These were generally similar to the R5O-4 but had 14-seats. Three went to the USCG in 1942 and at least one went to the USMC in 1943.

R5O-6: Thirty five USAAF C-60A-5-LOs transferred to the USN. Powered by two 1,200 hp (895 kW) Wright R-1820-87 nine-cylinder, single-row, air-cooled radial engines, these aircraft had 18 paratroop seats. Deliveries were made to the USMC starting in 1943.

OPERATIONAL HISTORY

The original five Lodestars were purchased by the USN as staff and command transports to serve high-level personnel, e.g., the Secretary of the Navy, the Assistant Secretary of the Navy, the Chief of the Bureau of Aeronautics (BuAer), the Commandant of the USMC, the Navy Inspector General, et al. The first R5O was delivered to Naval Air Station (NAS) Pensacola, Florida in May 1940. On 31 December 1941, two R5O-1s and two R5O-3s were at NAS Anacostia, District of Columbia and the R5O-2 was at NAS Pensacola.

The later models of the Lodestar served several functions. First, they were also assigned as staff and command transports to lower level commands; (2) they were assigned as base hacks to be used for the transport of personnel or equipment and (3) they were used for ferrying pilots.

The great buildup of the U.S. military forces beginning in 1940 and 1941 created problems in delivering aircraft from the factory to modification centers and/or embarkation points for delivery to the fleet. Initially, the USN established Air Delivery Units (ADUs) but the process was formalized on 1 December 1943 when the Naval Air Ferry Command (NAFC) was established at NAS New York, New York (Floyd Bennett Field) as a wing of the Naval Air Transport Service (NATS). At the same time, three Air Ferry Squadrons were commissioned, Air Ferry Squadron One (VRF-1) at NAS New York; VRF-2 at Naval Air Facility (NAF) Columbus, Ohio; and VRF-3 at NAS Terminal Island, California. A fourth squadron, VRF-4, was formed at NAS New York on 15 November 1944. The ADUs and ferry squadrons used small transports like the R5O-6, to ferry pilots to the manufacturer=92s plant to pick up the aircraft and then the transport would fly to the station where the aircraft were delivered to bring the pilots back to either the factory for another flight or to their home station.

The USMC also received R5Os during the war and used them for staff and command transports. At least one R5O-4 was received in 1942 followed by a small number of R5O-4, -5 and -6 aircraft starting in 1943. The disposition of the six Marine R5Os on 31 August 1943 was:

Marine Corps Air Station (MCAS) Cherry Point, North Carolina
   One R5O-6 assigned to Marine Utility Squadron Three Hundred Fifty Two (VMJ-352)
MCAS El Toro, California
   One R5O-6 assigned to Headquarters Squadron Twenty Three (Hedron 23)
   One R5O-6 assigned to Hedron 41
MCAS Ewa, Territory of Hawaii
   One R5O-5 assigned to Hedron, Marine Aircraft Wings, Pacific
MCAS Quantico, Virginia
   One R5O-4 assigned to the Base Air Detachment
MCAS Santa Barbara, California
   One R5O-6 assigned to Hedron 42

The twelve R5Os transferred to the USCG were used for administrative flights with the aircraft initially based at Coast Guard Air Station (CGAS) Elizabeth City, North Carolina and NAS New York; R5Os were later based at Washington National Airport, District of Columbia.

SPECIFICATIONS

Wing Span: 65 feet 6 inches (20.0 meters)
Length: 49 feet 10 inches (15.2 meters)
Height: 12 feet 9 inches (3.9 meters)
Wing Area: 551 square feet (51.2 square meters)
Empty Weight
   R5O-2: 11,250 pounds (5,103 kg)
  R5O-3: 12,759 pounds (5,787 kg)
  R5O-4: 13,040 pounds (5,915 kg)
  R5O-5: 13,104 pounds (5,944 kg)
   R5O-6: 12,500 pounds (5,670 kg)
Maximum Takeoff Weight
   R5O-2: 19,200 pounds (8,709 kg)
  R5O-3: 19,500 pounds (8,845 kg)
  R5O-4 and -5: 21,500 pounds (9,752 kg)
   R5O-6: 21,000 pounds (9,525 kg)
Maximum Speed
   R5O-2: 218 mph at 8,000 feet (350.8 km/h at 2,438 meters)
R5O-6: 266 mph at 17,150 feet (428.1 km/h at 5,227 meters)
Cruising Speed
   R5O-2: 197 mph (317.0 km/h)
R5O-6: 200 mph (321.9 km/h)
Service Ceiling
   R5O-2: 20, 400 feet (6,218 meters)
  R5O-6: 30,100 feet (9,174 meters)
Normal Range
   R5O-2: 1,800 miles (2,897 km)
R5O-6: 950 miles (1,529 km)
Maximum Range
   R5O-2: 3,200 miles (5,150 km)
  R5O-6: 2,500 miles (4,023 km)
Armament: None