World War 2 In Review

Northrop XP-79: American Flying Wing Fighter Project

The Northrop XP-79, USAAF project number MX-365, was a rocket and jet-powered flying wing fighter aircraft, designed by Northrop. The pilot operated the aircraft in a prone position, permitting him to withstand much greater g-forces in pitch. It also used a welded magnesium monocoque structure instead of riveted aluminum.

Design and Development

In 1942, Jack Northrop conceived the XP-79 as a high-speed rocket-powered flying-wing fighter aircraft. In January 1943, a contract for two prototypes under the XP-79 designation was issued by the United States Army Air Forces (USAAF).

It was planned to use a 2,000 lbf (8,900 N) thrust XCALR-2000A-1 "rotojet" rocket motor from Aerojet that used mono-ethylaniline fuel and red fuming nitric acid (RFNA) oxidizer. However, the rocket motor, which used canted rockets to drive turbo-pumps was unsatisfactory and the aircraft was fitted with two Westinghouse 19B turbojets and re-designated XP-79B.

The XP-79 was built using a welded magnesium alloy monocoque structure with a leading edge thickness of 0.75 in (19 mm) which thinned out to 0.125 in (3.2 mm) at the trailing edge.

The pilot controlled the XP-79 through a tiller bar and intakes mounted at the wingtips supplied air for the unusual bellows-boosted split elevons which opened differentially to provide lateral (yaw) control, by increasing drag on one side of the aircraft, in addition to providing roll and pitch. The aircraft was also fitted with airbrakes outboard of them, also for yaw control. No rudders were used, and the vertical surfaces were simple fixed fins with no flight controls.

MX-324 and MX-334

Northrop was given a contract to build three glider demonstrators to test the design. Given the Northrop designation NS-12, the three gliders were also given project numbers from the USAAF. Confusingly, two project numbers were used, one MX-324 when discussing secret aspects of the powered gliders, and another, MX-334, relating to the aircraft when being built and flown as pure gliders.

The MX-334 was a flying wing glider with no tail surfaces, similar in layout and construction to the Northrop N-9M. Completed in late Spring 1943, MX-334 No.1 was tested in NACA Langley's wind tunnel, after which a large wire-braced fin was added for directional stability at high speeds. The first flight attempts were carried out by the No.2 aircraft towed behind a Cadillac car for low level take-off and landing tests, with no success. After modifications the first launch was carried out on 4 September 1943, towed behind a large truck. For more comprehensive testing, a Lockheed P-38 Lightning was used to tow the aircraft on 2 October 1943.

In early 1944 the No.2 aircraft was modified to take the 2,009 lbf (8,940 N) Aerojet XCAL-200 rocket motor, and reverted to the secret MX-324 designation. Testing with the rocket motor commenced on 22 June 1944, with the first aerotow launch for a powered flight on 5 July 1944, making it the first US-built rocket-powered aircraft to fly. Flight testing was concluded by 1 August 1944 and the two remaining aircraft were disposed of. MX-334 No.3 was written off on its second flight, on 10 November 1943, after Harry Crosby lost control in the prop-wash of the P-38 tug.

Testing

Following delays due to burst tires and brake problems during taxiing trials at Muroc dry lake, the XP-79B made its first flight on 12 September 1945, however, 15 minutes into the flight control was lost for unknown reasons while performing a slow roll. The nose dropped, and the roll continued with the aircraft impacting the ground in a vertical spin. Test pilot Harry Crosby had attempted to bail out but was struck by the aircraft and died. Shortly thereafter, the project was canceled along with work on the second prototype.

Variants

NS-12: Northrop company designation for the MX-324 program.

NS-14: Northrop designation for the XP-79 program.

MX-324: The "secret" designation for the powered version of the MX-334 glider. Only used for the no.2 glider, when powered by a single 200 lbf (890 N) Aerojet XCAL-200 liquid-fueled rocket engine.

MX-334: The designation used to describe the pure glider version (including the No.2 aircraft before it was fitted with the rocket engine).

MX-365: The USAAC project number for the XP-79 program.

XP-79: The initial design for a rocket powered fighter, to have been powered by 2 x 2,000 lbf (8.9 kN) Aerojet XCAL-2000 liquid-fueled rocket engine.

XP-79B: Three aircraft were ordered but only one was completed, crashing on its first flight on 12 September 1945.

Type: Interceptor

Manufacturer: Northrop Corporation

Designer: Jack Northrop

Status: Crashed, out of service

Primary user: United States Army Air Forces

Number built: 1

First flight: 12 September 1945

Retired: 12 September 1945

Crew: 1

Length: 13.98 ft (4.26 m)

Wingspan: 37.99 ft (11.58 m)

Height: 7.58 ft (2.31 m)

Wing area: 278 sq ft (25.8 m2)

Aspect ratio: 5.19

Airfoil: NACA 66,2-018

Empty weight: 5,842 lb (2,650 kg)

Gross weight: 8,669 lb (3,932 kg)

Fuel capacity: 300 US gal (250 imp gal; 1,100 L)

Powerplant: 2 × Westinghouse 19B axial flow turbojet, 1,150 lbf (5.1 kN) thrust each

Maximum speed: 547 mph (880 km/h, 475 kn)

Cruise speed: 480 mph (770 km/h, 420 kn)

Range: 993 mi (1,598 km, 863 nmi)

Endurance: 2.45 hours

Service ceiling: 40,000 ft (12,000 m)

Rate of climb: 4,000 ft/min (20 m/s)

Wing loading: 31 lb/sq ft (150 kg/m2)

Thrust/weight: 0.27

Armament:

Guns: 4 x 0.5 in (12.70 mm) machine-guns

Bibliography

Jenkins, Dennis R.; Landis, Tony R. (2008). Experimental & prototype U.S. Air Force jet fighters. North Branch, MN: Specialty Press.

Pelletier, Alain J. "Towards the Ideal Aircraft: The Life and Times of the Flying Wing, Part Two". Air Enthusiast, No. 65, September–October 1996, pp. 8–19.

Northrop XP-79B.

Cleaned up version of the above photo.

Northrop MX-334 experimental rocket-powered flying wing. 1944.

Northrop XP-79B.

Northrop XP-79B. A contract for three XP-79s was signed in January 1943 and subsequently subcontracted to Avion Inc. The third aircraft ordered (43-52437) was redesigned for turbojet engines, designated XP-79B, and delivered in June 1945.

Northrop XP-79B. The first flight of the aircraft resulted in tragedy, when on 12 September 1945, after only 14 minutes in the air, the XP-79B began an uncontrollable roll from which the pilot was unable to recover. The project was cancelled following the accident.

Northrop XP-79B.

Vultee V-11 / V-12 / YA-19: American Attack Aircraft

The Vultee V-11 and V-12 were American stressed-skin monocoque monoplane attack aircraft of the 1930s. Developed from the Vultee V-1 single-engined airliner, the V-11 and V-12 were purchased by several nations for their armed forces, including China, who used them in combat against Japanese forces in the Second Sino-Japanese War. The United States Army Air Corps purchased seven V-11s as the YA-19 in the years before World War II, testing them to gather data to compare against twin engine light attack aircraft.

Design and Development

In 1935, Vultee produced a light bomber derivative of their single-engined passenger transport, the Vultee V-1, which, while demonstrating good performance, was only sold in small numbers owing to restrictions placed on the use of single-engined aircraft for scheduled passenger transport operations.

The resulting aircraft, the Vultee V-11, retained the single-engined, low wing format and all-metal stressed skin structure of the V-1. It combined a new fuselage with accommodation for the three crew members under a long greenhouse canopy with the wings and tail surfaces of the Vultee V-1.

According to Jonathan Thompson, "Based on the V-1A, the V-11 was a modern, fast and effective military airplane when it appeared in 1935; during the next three years 102 V-11s in six variations were sold to four countries - the Soviet Union, China, Turkey and Brazil - before the Air Corps took seven A-19s. An improved version known as the AB-2 (Attack bomber, 2nd type) and later as the V-12, was tested in 1938 and provided the basis for further sales to China, bringing the total V-11 models and derivatives, including those built under license, to an estimated 225."

Duplicate emergency flying controls were provided for the observer/dorsal gunner in the V-11GB. According to Thompson, "Below his seat is the retractable bombardier's hatch; he lay prone, facing forward for the bomb run or rearward to use the ventral gun."

Type: Ground attack

Manufacturer: Vultee

Designer: Gerard Freebairn Vultee

Status: retired

Primary users:

Republic of China Air Force

Turkish Air Force

Soviet Air Forces

Brazilian Army Aviation

Number built: 175 + 2 plus as many as 4 more in Russia, and as many as 45 additional airframes that were delivered as parts sets but probably not assembled in China, for a maximum of 224.

Manufactured: 1935–1940

Introduction date: 1937

First flight: 17 September 1935

Developed from: Vultee V-1

Operational History

China

An initial order for 30 two-seat V-11Gs was placed by China before the end of 1935. This was followed in 1939 by orders for two versions (the V-12-C and V-12D) of the more powerful V-12 variant. The majority of these were planned to be assembled from kits at the Central Aircraft Manufacturing Company factory at Loiwing near the China-Burma border, and while the first batch of 25 V-12-Cs were completed successfully, the factory was heavily bombed just after assembly of the first V-12-Ds commenced. This resulted in the part built airframes being evacuated to India, where it was planned that the aircraft be completed at the Hindustan Aircraft Limited factory in Bangalore. However, after a few were assembled, production was stopped as the factory was diverted to more urgent overhaul work.

The V-11s and V-12s served as light bombers and achieved some success, including a mission by 4 aircraft to bomb the Japanese held airfield at Yuncheng on February 5, 1939, by the 10th Squadron of the Republic of China Air Force, before the aircraft were withdrawn from bombing missions to training and liaison duties in 1940.

Brazil

In February 1939, the Brazilian Army Air Corps acquired the first 10 Vultee V-11–GB2s for long range bombing. 26 aircraft were eventually used by the Brazilian Air Force.

A 3,250 km (2,020 mi) non-stop flight was made across the Brazilian hinterland in 11 hours and 45 min on 8 November 1939 using a V-11.

On 26 August 1942, a U-boat was attacked 50 miles off the town of Ararangua off the southern coast of Brazil. Despite the unsuitability for anti submarine operations, the aircraft flew low and dropped its load of three 250 lb (110 kg) bombs, some of which exploded around the submarine, however the blast damaged the low flying aircraft.

Soviet Union

In 1936, the Soviet Union purchased four three-seat V-11-GB aircraft, together with a production license. The aircraft entered Soviet production in 1937 as the BSh-1 (Bronirovanny Shturmovik), but the armor fitted for the ground attack role unacceptably reduced performance and production was stopped after 31 aircraft. They were transferred to Aeroflot and redesignated PS-43 for use as high speed transports until the German invasion in 1941, when they were returned to the Air Force for liaison purposes.

United States

In the late 1930s, the United States Army Air Corps favored twin-engine light attack aircraft but seven YA-19 aircraft were ordered in the summer of 1938 for comparison purposes. The YA-19s were armed with six .30 in (7.62 mm) machine guns and 1,080 lb (490 kg) bombs in an internal bomb bay, powered by a 1,200 hp (890 kW) Twin Wasp radial engine and was manned by a crew of three including a pilot, observer/gunner, and bombardier/photographer.

An unusual feature of the YA-19 design was its horizontal stabilizer which was located forward of the vertical tail. The small size of the vertical stabilizer caused yaw instability so the last YA-19 (S/N 38-555) was equipped with enlarged vertical stabilizer.

Service tests showed that twin-engine attack aircraft were faster, could be better armed and carried a larger bomb load so no further YA-19s were ordered. After comparison tests five YA-19s were redesignated A-19 and assigned to the 17th Attack Group at March Field in California for a brief period before being transferred to the Panama Canal Zone for utility transport and liaison duties. The A-19 never saw combat and was quickly withdrawn in the early 1940s.

Variants

Vultee Designations

V-11: First prototype fitted with 750 hp (560 kW) Wright SR-1820-F53 Cyclone driving a two-bladed Hamilton Standard controllable-pitch propeller, which crashed killing both pilot and the project engineer.

V-11-A: Second prototype, similar to first V-11, but with a three-bladed constant speed propeller.

V-11-G: Initial production two-seat light bomber. Powered by an 850 hp (630 kW) Wright R-1820-G2 Cyclone engine. 30 built for China.

V-11-GB: Three-seat version of V-11. 4 aircraft purchased by Soviet Union (2 as pattern aircraft), 40 by Turkey and others.

V-11-GB2: 26 purchased by Brazil – generally similar to V-11-GB

V11-GB2F: Final example for Brazil fitted with floats, however it wasn't accepted.

V-11-GBT: Re-designation of V-11-GB for Turkey

V-12: Revised version of three-seat bomber with refined aerodynamics and more power. One prototype flew in 1939 powered by Pratt & Whitney R-1830 Twin Wasp engine.

V-12-C: Production version of V-12 for China. Powered by R1820-G105B Cyclone engine. 26 built, one by Vultee and remaining 25 assembled in China.

V-12-D: Revised version with new fuselage and powered by 1,600 hp (1,200 kW) Wright R-2600 Cyclone 14 engine. 52 ordered for China, two pattern aircraft built by Vultee and 50 for local assembly.

V-52: Unbuilt observation design based on YA-19.

USAAC Designations

XA-19: Prototype.

Crew: Three (pilot, observer/gunner and bombardier/photographer)

Length: 37 ft 10 in (11.53 m)

Wingspan: 50 ft 0 in (15.24 m)

Height: 10 ft 0 in (3.05 m)

Wing area: 384 sq ft (35.7 m2)

Airfoil: Clark Y

Empty weight: 6,452 lb (2,927 kg)

Gross weight: 10,420 lb (4,726 kg)

Maximum takeoff weight: 16,285 lb (7,387 kg)

Fuel capacity: 311–330 US gallons (1,180–1,250 L)

Powerplant: 1 × Pratt & Whitney R-1830-17 Twin Wasp 14-cylinder two-row air-cooled radial engine, 1,200 hp (890 kW)

Propellers: 3-bladed Hamilton Standard variable-pitch propeller

Maximum speed: 230 mph (370 km/h, 200 kn) at 6,500 ft (2,000 m)

Cruise speed: 207 mph (333 km/h, 180 kn)

Minimum control speed: 80 mph (130 km/h, 70 kn)

Range: 1,110 mi (1,790 km, 960 nmi) with 1,080 lb (490 kg) of bombs

Ferry range: 1,350 mi (2,170 km, 1,170 nmi)

Service ceiling: 20,500 ft (6,200 m)

Rate of climb: 1,320 ft/min (6.7 m/s)

Armament:

Guns:

4 x forward-firing .30 in (7.62 mm) machine guns in wings

1 x dorsal .30 in (7.62 mm) machine gun

1 x ventral .30 in (7.62 mm) machine gun

Bombs: 6 x 30 lb (14 kg) in cells semi-recessed in wing center section and 1,100 lb (500 kg) externally

YA-19: Variant of V-11-GB for United states Army Air Corps. Seven examples built.

YA-19A: The last YA-19 was redesignated and completed as an engine test bed. Equipped with enlarged vertical stabilizer (for improve directional stability) and powered by Lycoming O-1230 (12-cylinder opposed) engine.

YA-19B: The second YA-19 built was redesignated after being fitted with a Pratt & Whitney R-2800 radial engine as an engine test bed.

YA-19C: The YA-19A was redesignated after being fitted with a Pratt & Whitney Twin Wasp R-1830-51 engine. Performance was similar to the YA-19.

A-19: The remaining five YA-19s were redesignated A-19 after assignment to active duty.

Soviet Designations

BSh-1: Soviet licensed armored ground attack version. Powered by 920 hp (690 kW) M-62. Production stopped after at least 31 built.

PS-43: Designation for BSh-1 when used by Aeroflot as light transport.

Operators

Brazil

Brazilian Army Aviation – Vultee V-11-GB2 (25 delivered)

Brazilian Air Force - aircraft transferred when Air Force created

Republic of China

Chinese Nationalist Air Force

14th Squadron – Vultee V-11G (30), V-12C (25 delivered from order of 26, which was built but never delivered) and Vultee V-12D (52 delivered)

Soviet Union

Soviet Air Forces – Vultee V-11GB (4 delivered) & BSh-1 (31-35 built at Moscow Menzhinskii factory)

Turkey

Turkish Air Force

2nd Regiment – Vultee V-11GB (41 delivered)

United States

United States Army Air Corps – A-19/V-11GB (7 delivered)

Bibliography

Baugher, Joseph F. (1 July 2000). "Vultee XA-19". www.joebaugher.com.

Deryakulu, Nejat (November 1995). "Les Vultee V-11GBT turcs" [Turkish Vultee V-11GBTs]. Avions: Toute l'aéronautique et son histoire (in French) (32): 29–32.

Green, William; Swanborough, Gordon, eds. (July 1972). "Those Versatile Vultees". Air Enthusiast. Vol. 3, no. 1. pp. 27–32, 38–42.

Johnson, E.R. (2008). American Attack Aircraft Since 1926. McFarland. pp. 30-32.

Lednicer, David (15 September 2010). "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu.

Norton, William (2008). U.S. Experimental & Prototype Aircraft Projects: Fighters 1939-1945. North Branch, MN: Specialty Press. p. 182.

Swanborough, Gordon; Bowers, Peter M. (1989). United States Military Aircraft Since 1909. Smithsonian.

Wegg, John (1990). General Dynamics Aircraft and their Predecessors. London: Putnam.