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| C-76 Caravan | |
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| Role | Medium transport |
| National origin | United States |
| Manufacturer | Curtiss-Wright |
| First flight | 1 January 1943 |
| Status | Cancelled |
| Primary user | United States Army Air Force |
| Number built | 5 |
The Curtiss-Wright C-76 Caravan (company designation CW-27) was an all-wood military transport aircraft. The C-76 was intended as a substitute standard aircraft in the event of expected wartime shortages of light alloys. However, both prototype and production aircraft failed several critical flight and static tests, and after U.S. aluminum production proved sufficient for wartime defense requirements, orders for the C-76 were cancelled and production terminated.
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Design and development
In 1941, Curtiss-Wright was contracted by the United States Army Air Force to design and construct an all-wood military transport aircraft, with performance specifications meeting or exceeding that of the C-47 Skytrain then in service.
The Curtiss-Wright CW-27 was designed by Curtiss-Wright's chief designer George A. Page, Jr. as a high-wing, twin-engine, cargo transport aircraft, utilizing plywood construction with a tricycle undercarriage. Though the British de Havilland Mosquito had successfully employed a ply construction using a balsa wood core and birch hardwood exterior, Curtiss-Wright engineers, using research provided by Forest Products Laboratory,1 rejected this approach, insisting instead on a mahogany ply construction, which greatly increased the plane's weight.2 At Curtiss' request, Army Materiel Command laid in large supplies of mahogany, and a number of furniture manufacturers, including the Baldwin Piano Company, were subcontracted to build components for the plane, which would be assembled at Curtiss-Wright's new defense plant in Louisville, Kentucky.3
A radial engine was mounted on each wing, and the aircraft was capable of carrying 23 personnel or a cargo payload. The original contract called for 11 YC-76 pre-production aircraft, and the first aircraft would be built and tested at Curtiss-Wright's St. Louis, Missouri Division plant. Subsequently, orders for five C-76 production aircraft and nine revised YC-76A were placed by the USAAF, with line production to commence at the Curtiss-Wright plant in Louisville as well as a Higgins Aircraft factory in New Orleans, Louisiana.45 To keep the plywood flexible during construction the factory was kept hot and damp.6 The prototype YC-76 first flew on January 1, 1943.
Only five production aircraft were completed in 1943: three from Curtiss-Wright's St. Louis Division, and two from the Louisville, Kentucky plant (the Higgins Aircraft complex in New Orleans had not been completed at the time of the contract's cancellation).7
Operational history
The C-76 proved severely underpowered from the start, with a cruise speed of 160 mph, a service ceiling of 22,600 feet, a range of only 750 miles, and a cargo capacity of under 8,000 lbs. Colonel J.W. Sessums, a USAAF officer at the Air Materiel Command at Wright Field, later related:
The first flight [of the C-76] was made and the airplane was very heavy. It developed some serious vibrations. In fact, the pilot was awful glad to make a quick circuit to get back on the ground...two of the Curtis test pilots took it out on a flight and the Army requested that our project officer on the airplane be allowed to fly along on this trip. The Curtiss Company refused. We were very glad that they refused because on this second flight, it [the C-76] flew apart and the pilots were lost and so was the plane.8
Compared to other cargo aircraft then coming into service, the C-76 was already obsolescent, even allowing for its 'war-priority' method of construction. In addition, the C-76 failed a number of critical flight tests.9 It was discovered in testing that the C-76 was unstable when not carrying a cargo load; in order to obtain a stable center of gravity, the plane had to be ballasted beyond its maximum permissible gross takeoff weight.1011 At any speed, or in any gusting wind, the C-76's elevators would flap back and forth violently.12 The wing structure failed in eight separate static tests, sometimes with a load as low as 40% of the wing's rated capacity.13. The wing failures were attributed by some sources to the failure of the fasteners used to secure the wood components of the aircraft.1415 Numerous additional fasteners, metal stirrups, and wood ply reinforcements were added to the structure in an effort to strengthen it, thereby increasing the plane's overall weight.16
At the Louisville plant, Curtiss line workers would later recall two C-76 production planes at the factory, with one plane cannibalized to keep the other in flyable condition.17 The first C-76 produced at the Louisville plant crashed in a test flight in mid-1943.1819 As war priority measures designed to increase aluminum production proved successful, the feared shortage of light alloys never materialized. Moreover, USAAF Training Command had begun to forward widespread complaints of insufficient service life on their wooden-winged Fairchild PT-19 primary trainers when exposed to high heat in training bases located in Texas and Florida.20 The War Department cancelled its orders for the C-76 in August 19432122, and the remaining prototype aircraft were recalled from testing and active service. In the interim, the Curtiss-Wright plants at Buffalo, New York and Louisville, Kentucky went over to full production of the C-46 Commando.2324 USAAF Materiel Command later estimated the entire C-76 project cost the U.S. government $400 million dollars and several months in lost production time.25
Specification
General characteristics
- Crew: 1-2
- Capacity: 23 total
- Length: 68.33 ft (20.83 m)
- Wingspan: 108.17 ft (32.97 m)
- Height: 27.25 ft (8.31 m)
- Wing area: 1560.05 ft² (144.93 m²)
- Empty weight: 18262 lb (8301 kg)
- Max takeoff weight: 28000 lb (12701 kg)
- Powerplant: 2× Pratt & Whitney R-1830-92 Twin Wasp radial piston engines, 1200 hp (895 kW) each
Performance
- Maximum speed: 192 mph (309 km/h)
- Cruise speed: 160 mph (260 km/h)
- Range: 750 mi (1207 km)
- Service ceiling 22,600 ft (6,888 m)
See also
Related lists
References
- ^ Forest Products Journal, January 1, 2007: "G.A. Page, chief engineer of the Curtiss-Wright Division at St. Louis, Mo., wrote, "It [the Design Handbook] has expedited and facilitated our work in connection with the design of the C-76 airplane to a degree that is hard to estimate." http://goliath.ecnext.com/coms2/gi_0199-6309544/Forest-Products-Laboratory-supporting-
- ^ Sessums, Col. J.W., Design and Engineering Problems of Aircraft Production {Restricted}, May 14, 1946, pp. 6-8 http://www.ndu.edu/library/ic1/L46-084.pdf
- ^ Sessums, Col. J.W., Design and Engineering Problems of Aircraft Production {Restricted}, May 14, 1946, pp. 6-8 http://www.ndu.edu/library/ic1/L46-084.pdf
- ^ Kleber, John E., The Encyclopedia of Louisville, University Press of Kentucky (2001) ISBN 0813121000, 9780813121000
- ^ Freeman, Paul, Abandoned & Little-Known Airfields, Louisiana: Eastern New Orleans area http://members.tripod.com/airfields_freeman/LA/Airfields_LA_NewOrleans_E.html
- ^ Curtiss C-76 Caravan http://aeroweb.brooklyn.cuny.edu/specs/curtiss/c-76.htm
- ^ Freeman, Paul, Abandoned & Little Known Airfields: Louisiana: Eastern New Orleans area, http://members.tripod.com/airfields_freeman/LA/Airfields_LA_NewOrleans_E.html
- ^ Sessums, Col. J.W., Design and Engineering Problems of Aircraft Production {Restricted}, May 14, 1946, pp. 6-8 http://www.ndu.edu/library/ic1/L46-084.pdf
- ^ Mansfield, Howard, Skylark: The Life, Lies, and Inventions of Harry Atwood, UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205
- ^ Mansfield, Howard, Skylark: The Life, Lies, and Inventions of Harry Atwood, UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205
- ^ Sessums, Col. J.W., Design and Engineering Problems of Aircraft Production {Restricted}, May 14, 1946, pp. 6-8 http://www.ndu.edu/library/ic1/L46-084.pdf
- ^ Mansfield, Howard, Skylark: The Life, Lies, and Inventions of Harry Atwood, UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205
- ^ Curtiss-Wright Corporate Records, Static Tests of Curtiss-Wright C-76 Wings, ENG-51-C359-10, 7/24/43
- ^ Mansfield, Howard, Skylark: The Life, Lies, and Inventions of Harry Atwood, UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205
- ^ Aviation Enthusiast Corner, Curtiss C-76 Caravan http://aeroweb.brooklyn.cuny.edu/specs/curtiss/c-76.htm
- ^ Mansfield, Howard, Skylark: The Life, Lies, and Inventions of Harry Atwood, UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205
- ^ Aviation Enthusiast Corner, Curtiss C-76 Caravan http://aeroweb.brooklyn.cuny.edu/specs/curtiss/c-76.htm
- ^ Kleber, John E., The Encyclopedia of Louisville, University Press of Kentucky (2001) ISBN 0813121000, 9780813121000, p. xxvii
- ^ Army Air Forces in World War II, Vol. VII,http://www.ibiblio.org/hyperwar/AAF/VII/AAF-VII-1.html
- ^ Sessums, Col. J.W., Design and Engineering Problems of Aircraft Production {Restricted}, May 14, 1946, pp. 6-8 http://www.ndu.edu/library/ic1/L46-084.pdf
- ^ Freeman, Paul, Abandoned & Little Known Airfields: Louisiana: Eastern New Orleans area, http://members.tripod.com/airfields_freeman/LA/Airfields_LA_NewOrleans_E.html
- ^ News Article, New York Times, August 4, 1943, October 17, 1943
- ^ Curtiss C-46 Commando http://www.faqs.org/docs/air/avc46.html
- ^ News Article, New York Times, August 11, 1944
- ^ Sessums, Col. J.W., Design and Engineering Problems of Aircraft Production {Restricted}, May 14, 1946, pp. 6-8 http://www.ndu.edu/library/ic1/L46-084.pdf
- The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.
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- This page was last modified on 13 December 2008, at 17:54.
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