C-76 Caravan

infobox Aircraft
name = C-76 Caravan



caption =
type = Medium transport
national origin = United States
manufacturer = Curtiss-Wright
designer =
first flight = 1 January 1943
introduced =
retired =
produced =
primary user = United States Army Air Force
more users =
number built = 5
status = Cancelled
unit cost =
developed from =
variants with their own articles =

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.

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, [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-] rejected this approach, insisting instead on a mahogany ply construction, which greatly increased the plane's weight. [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] 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. [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]

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. [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] To keep the plywood flexible during construction the factory was kept hot and damp. ["Curtiss C-76 Caravan" http://aeroweb.brooklyn.cuny.edu/specs/curtiss/c-76.htm] 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). [Freeman, Paul, "Abandoned & Little Known Airfields: Louisiana: Eastern New Orleans area", http://members.tripod.com/airfields_freeman/LA/Airfields_LA_NewOrleans_E.html]

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." [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]

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. [Mansfield, Howard, "Skylark: The Life, Lies, and Inventions of Harry Atwood", UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205] 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. [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] At any speed, or in any gusting wind, the C-76's elevators would flap back and forth violently. [Mansfield, Howard, "Skylark: The Life, Lies, and Inventions of Harry Atwood", UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205] The wing structure failed in eight separate static tests, sometimes with a load as low as 40% of the wing's rated capacity. [Curtiss-Wright Corporate Records, "Static Tests of Curtiss-Wright C-76 Wings", ENG-51-C359-10, 7/24/43] . The wing failures were attributed by some sources to the failure of the fasteners used to secure the wood components of the aircraft. [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] 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. [Mansfield, Howard, "Skylark: The Life, Lies, and Inventions of Harry Atwood", UPNE (1999) ISBN 0874518911, 9780874518917, pp. 204-205]

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. [Aviation Enthusiast Corner, "Curtiss C-76 Caravan" http://aeroweb.brooklyn.cuny.edu/specs/curtiss/c-76.htm] The first C-76 produced at the Louisville plant crashed in a test flight in mid-1943. [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] 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. [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 War Department cancelled its orders for the C-76 in August 1943 [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] , 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. ["Curtiss C-46 Commando" http://www.faqs.org/docs/air/avc46.html] [News Article, "New York Times", August 11, 1944] 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. [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]

pecification

aircraft specifications
plane or copter?=plane
jet or prop?=prop
crew=1-2
capacity=23 total

length main=68.33 ft
length alt=20.83 m
span main=108.17 ft
span alt=32.97 m
height main=27.25 ft
height alt=8.31 m
area main=1560.05 ft²
area alt=144.93 m²
airfoil=
empty weight main= 18262 lb
empty weight alt=8301 kg
max takeoff weight main=28000 lb
max takeoff weight alt=12701 kg

engine (prop)= Pratt & Whitney R-1830-92 Twin Wasp
type of prop= radial piston engines
number of props= 2
power main=1200 hp
power alt=895 kW
cruise speed main=160 mph
cruise speed alt=260 km/h
max speed main=192 mph
max speed alt=309 km/h
range main=750 mi
range alt=1207 km
ceiling main=22,600 ft
ceiling alt=6,888 m
climb rate main=
climb rate alt=

ee also

aircontent
related=

similar aircraft=

lists=
* List of military aircraft of the United States

see also=

References

*