Lockheed C-69 Constellation

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C-69 Constellation
A C-69 Constellation in flight
A C-69 Constellation in flight
Role Transport
National origin United States
Manufacturer Lockheed
Designer Kelly Johnson
First flight January 9, 1943
Introduction July 28, 1943
Retired 1945 (except C-69C)
Status Retired
Primary user United States Army Air Forces
Produced 1942–1945
Number built 22
Variants
L-049 Constellation

The Lockheed C-69 Constellation was a four-engined, propeller-driven military transport aircraft developed during World War II. It was co-developed with the Lockheed Constellation airliner.

It first flew in 1943, and production of the 22 constructed was shared between the United States Army Air Forces (15) and commercial carriers. Most of the C-69 aircraft built were later converted into civilian airliners under the designation Lockheed L-049 Constellation.[1]

Design and development

Following the

Pan American World Airways were also requisitioned. The 50 L-049s both airlines had on order were to be redesignated C-69 and C-69A, respectively, and used as troop transport aircraft. The 30 L-149 aircraft Pan Am had on order were replaced by the similar model L-349 (difference being the cargo door on the upper left hand side of the aircraft and the ability to carry cargo) and designated C-69B. Another 180 C-69B aircraft were ordered increasing the figure to 210. Due to the direction the war was heading during summer 1942, the need for a large troop transport capable of crossing the Atlantic Ocean or Pacific Ocean (by flying from island to island) became more important. This would help avoid the risks the convoys in the Atlantic were facing due to U-boat attacks. The Douglas C-54 Skymaster planned for these roles wasn't completely capable. So on September 29, 1942, the United States Department of War
signed contract W535 AC-26610. With this contract, the nine L-049 aircraft under construction for TWA were purchased and 150 more C-69A and C-69B aircraft were ordered along with C-69C (L-549) and C-69D VIP transport versions. In reality, only one C-69C was produced out of all these planned variants.

The prototype XC-69, registered NX25600, c. 1943.

Around the same time the decision regarding contract W535 AC-26610 was made, the prototype XC-69 was completed and rolled out in December 1942. The aircraft was painted in olive green and grey

Pratt & Whitney R-2800
had been taken up. This led to a new version designated XC-69E, but the project was eventually abandoned.

The sole C-69C after civilianization for BOAC as an L049E at London Heathrow in 1954

On January 9, 1943, after the last inspections had been carried out by the USAAF and Lockheed, the XC-69 finally took to the skies. For the occasion, Lockheed had borrowed the

Lockheed L-18 Lodestar acted as photo chase aircraft. After the experience Allen commented, "This machine works so well that you don't need me anymore!" Allen returned to Boeing. A seventh flight took place on January 18. This time, the landing gear doors were placed on the aircraft so the gear could be retracted (this was not done earlier to avoid any landing gear failure). On July 28, 1943, the XC-69 was symbolically handed over to the USAAF at Las Vegas, Nevada and given a military serial number 43-10309. Later that same day, the XC-69 returned to Lockheed for further testing. It is worth mentioning that the C-69 was able to attain a higher maximum speed than the Japanese Mitsubishi A6M Zero fighter.[2]

Major problems, however, surfaced with the R-3350 powerplant that powered the C-69, when an XB-29 test aircraft crashed into a Boeing factory. The accident killed 14 factory workers, Edmund Allen, and the rest of Allen's test crew. The cause was due to one of the aircraft's R-3350 engines catching fire and burning through the wing of the aircraft causing it to fail and dooming the XB-29. All aircraft fitted with the R-3350, including the C-69, were grounded until the investigation of the engine's failure was concluded. The conclusion led to a recommendation to replace the existing carburetors with more reliable ones. With that, testing resumed after June 18, 1943. A fuel leakage problem was discovered with the C-69 and wasn't solved until April 1944 when a new method of sealing the fuel tanks surfaced. More overheating, fire and other troubles continued with the R-3350 engines. This happened to the point where Lockheed started to doubt the abilities of the engine's manufacturer, Curtiss-Wright. Lockheed suggested to the USAAF that the C-69's engines be replaced by more reliable R-2800 radial engines. Instead, the USAAF ceased production of the R-3350 until the troubles that plagued the engines were solved. This caused the development of the C-69 to slow down and furthermore, the C-69 was not declared a priority. Lockheed continued to focus on building combat aircraft while the C-54 Skymaster, the C-69's competitor was already flying and officially ordered.

The second production C-69 had first flown in August 1943. Lockheed had hoped to produce four C-69 aircraft by the end of 1943, but due to the low importance of the C-69 to the USAAF, this didn't occur. On April 16, 1944,

Orville Wright, on what would be his last flight in an aircraft. Wright was allowed to control the aircraft momentarily during the flight. He even commented that the wingspan was greater than that of his first flight. The third C-69 was sent on a flight between New York City and Paris
on August 14, 1945 which showed its capability to cross the Atlantic. The test flight took less than 15 hours and was flown by a TWA crew.

Pima Air and Space Museum
.

Unfortunately for Lockheed, the C-69 became less important to the war effort as time progressed, especially since the tide of the war had turned in favor of the Allies. Only a small number of C-69 aircraft would see service in the last year of the war. Even so, Lockheed was able to conduct tests at the expense of the government to solve problems with the aircraft's design. Although the problems with the R-3350 were being solved, the B-29 had priority for the engines over the C-69. Even with all the effort put forth by Lockheed, the USAAF favored the C-54 Skymaster over the C-69. At the end of the war, only 22 C-69s were produced (seven of which were never delivered). Except for the C-69C, all other C-69s were declared surplus and sold on the civilian market between 1946 and 1947. These would later be converted by Lockheed into L-049 passenger aircraft for airline usage. The prototype XC-69 was converted into the sole XC-69E, which tested the possibility of using the R-2800 in place of the R-3350. This never happened. The XC-69E was later sold to the

Pima Air and Space Museum
, and is painted in full TWA livery.

Variants

Main article:
Lockheed Constellation variants
Variant Built
XC-69 1
C-69-1-LO 16
C-69-5-LO 4
C-69C-1-LO 1
XC-69
Unpressurized prototype version. One built.
C-69
Initial troop transport version. 13 built. Seven others were under construction, but converted to L-049 airliners while still on the assembly line.
C-69A
Troop transport with a different internal layout than the C-69. None built
C-69B
Long range troop and cargo transport with a cargo door on the left. None built. Company designation L-349.
C-69C
VIP transport version based on the initial C-69. One built. Company designation L-549.
C-69D
VIP transport with different engines with extra oil and fuel tanks. None built.
XC-69E
Prototype XC-69 converted to use four
R-3350
for testing purposes.

Specifications (C-69)

Data from Lockheed Constellation:From Excalibur to Starliner[3] and Dave's Warbirds.com [4]

General characteristics

  • Crew: 4
  • Length: 95 ft 2 in (29.01 m)
  • Wingspan: 123 ft (37 m)
  • Height: 22 ft 5 in (6.83 m)
  • Wing area: 1,650 sq ft (153 m2)
  • Airfoil: root: NACA 23018; tip: NACA 4412[5]
  • Empty weight: 50,000 lb (22,680 kg)
  • Max takeoff weight: 72,000 lb (32,659 kg)
  • Powerplant: 4 ×
    Wright R-3350-35 Duplex-Cyclone
    18-cylinder air-cooled radial piston engines, 2,200 hp (1,600 kW) each
  • Propellers: 3-bladed constant-speed propellers

Performance

  • Maximum speed: 330 mph (530 km/h, 290 kn) at 10,000 ft (3,048 m)
  • Cruise speed: 227 mph (365 km/h, 197 kn)
  • Range: 2,400 mi (3,900 km, 2,100 nmi)
  • Service ceiling: 25,030 ft (7,630 m)

See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

References

Notes

  1. ISBN 2-915239-62-2
    . p. 11 to p. 17.
  2. ^ Anorama – Lockheed Constellation – by Matthew Quiroz; Retrieved 10/8/11
  3. ^ Breffort, Dominique. Lockheed Constellation: from Excalibur to Starliner Civilian and Military Variants. Histoire and Collecions, 2006, p. 175.
  4. ^ Dave's Warbirds – C-69 Constellation Info; Retrieved 9/5/11
  5. ^ Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography

  • Breffort, Dominique (2006). "Lockheed Constellation: from Excalibur to Starliner Civilian and Military Variants". Histoire and Collecions. Paris: Print.
    ISBN 2-915239-62-2
    .

External links

Wikimedia Commons has media related to Lockheed Constellation.
  • Lockheed Constellation Survivors – A website that explains information and whereabouts of surviving Constellations of all variants, including the last surviving C-69 Constellation.
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