Allison V-1710

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Allison V-1710
Allison V-1710.jpg
Allison V-1710
Type: V- aircraft engine
Design country:

United StatesUnited States United States

Manufacturer:

Allison Engine Company

Production time:

1937-1949

Number of pieces:

approx. 70,000

Allison V-1710-2
Allison V-1710

The Allison V-1710 was a liquid-cooled V - 12 cylinder - aircraft engine of the Allison Engine Company . The only aircraft engine of this type developed in the USA was initially not used due to charger problems . After numerous improvements, there was great demand for the robust and reliable engine in the late stages of World War II .

Development history

The need of the United States Army Air Corps (USAAC) for a modern, 735 kW (1000 PS) strong aircraft engine for the new generation of aerodynamically designed bombers and fighters led to the development of a glycol-cooled engine by General Motors in 1929 acquired Allison Engine Company. In order to simplify production, the new construction could be equipped with various propeller drives and loaders . This made it possible to produce engines for various types of aircraft on just one production line.

The Great Depression delayed development until the first test on December 14, 1936 in a Consolidated XA-11A . On April 23, 1937, the V 1710-C6 was the first 1000 hp aircraft engine to pass the 150-hour type test of the USAAC. The engine was offered to various aircraft manufacturers, which led to use in the Curtiss YP-37 . Another flight competition for fighter aircraft had the result that it was used as a drive for the Lockheed P-38 , Bell P-39 , Curtiss P-40 and the North American P-51A .

The USAAC (from 1941: USAAF ) had decided to rely exclusively on turbochargers to increase performance at great heights . She believed the incorporation of turbochargers would enable her aircraft engines to outperform European competitors who only used mechanical superchargers directly powered by the engine . The high demand for metals for high-temperature alloys , especially tungsten , led to restrictions in the production of turbochargers during the war.

Finally, the USAAF reserved the majority of the turbochargers as a matter of priority for its few bombers. Most V-1710s were only equipped with a single-stage loader, which was sufficient for low altitudes, but had limited performance at high altitudes. After the United States entered World War II , some American fighter designs (such as the P-51 ) were modified to use the Rolls-Royce Merlin engine ( Packard Merlin V-1650 ) built under license by Packard . Its long-proven and optimized two-stage two-speed loader demonstrated excellent performance at great heights.

The version of the V-1710 with two-stage supercharger, introduced in the late phase of the war, greatly improved performance. The engine was later selected to power the Bell P-63 and North American P-82E / F series. In addition, it was used as an engine for many experimental and test aircraft such as the Republic XP-47A (AP-10), Curtiss XP-55 Ascender, XB-38 and Douglas XB-42 Mixmaster.

In total, over 70,000 V-1710s were built by Allison in Indianapolis during the war .

description

The design of the engine benefited from the General Motors philosophy of flexible assembly and production. Additional devices (pumps, loaders, etc.) were mounted at the rear of the crankcase and the propeller gearbox at the front . By doing this, changes to the loader and gear ratio of the loader were easy. This made it possible to adjust the full pressure heights in the range from 2400 to 7900 meters.

The P-39, P-63 and XB-42 used motors of the V-1710-E series, in which the built-in reduction gear was replaced by an extension shaft that drove the propeller by means of a separate reduction gear. Aircraft such as the P-38, P-40, P-51A, and P-82 used V-1710-F series engines with close-coupled propeller reduction gears.

Another feature of the V-1710 design was the ability to change the direction of propeller rotation using an inverted crankshaft . In addition, an impeller had to be installed in the drive train to the loader and the additional equipment. A starter with the correct direction of rotation completed the assembly. The wiring of the ignition and the firing sequence of the cylinders had to be adapted to the direction of rotation.

The V-1710 has often been criticized for not having a high-altitude loader. The comparison is usually to the late Rolls-Royce Merlin V-12 two-stage turbocharged engines built by Packard as the V-1650 and used in the P-51B / C / D Mustang. In the specification of the US Army, however, only an engine with a single-stage charger was required. For high-altitude aircraft, the turbocharger newly developed by the US Army, with which the P-37, P-38 and XP-39 were equipped, should be used. Separately from this, Allison developed a mechanical two-stage charger, which was an essential component of the P-63 and P-82 .

The first P-39, P-40 and P-51A powered by the V-1710 were only suitable for an operating altitude of up to 5000 meters. Since the V-1710 was available in relatively large numbers, it became a cornerstone for part of the Allied air forces in the non-European theaters of war. In total, over 60 percent of American fighters during World War II were powered by V-1710s.

The engine was continuously developed by Allison during the war. The initial output of 750 kW (1000 PS) was increased in stages up to the 1600 kW (2200 PS) of the V-1710-143 / 145 (G6R / L). However, most of the performance enhancements were due to the availability of high octane fuels. At the beginning of the war, Allison released engines with 860 kW (1150 hp) take-off power for emergency power of up to 1200 kW (1600 hp) in combat operations. Then the engine had to be dismantled and checked for further use.

Efficiency-enhancing improvements in the engine's production process have reduced manufacturing costs from US $ 25,000 to US $ 8500 and increased engine life from 300 to 1000 hours for the less stressed engines. The weight gains from these optimizations were only small, with the result that all engines produced more than 1.6 kW / kg (2.2 HP / kg) takeoff power.

The 250 P-82E / Fs built by North American after the war were used in many air defense functions until the early 1950s. This was the last military use of the V-1710, but not the end of its useful life, as thousands of surplus engines were now being sold. In the 1950s, drag star designers were interested in the V-1710 because of its great reliability. During this time, hydroplane racing also became a popular sport in the USA , and the output of the V-1710 was increased to up to 3000 kW (4000 hp). This was a level of performance Allison never envisioned when the engine was designed. To date, the turbocharged Allison V1710 holds the speed record for piston engine-powered boats and still proves to be competitive against turbine engines in hydroplane races.

Since specially made V8s have been available for drag racing and the hydroplanes have been partially converted to turbine power , tractor pullers around the world have been using the engine to this day. This also went hand in hand with unexpected performance development. Eventually, the warbird movement began to restore the classic fighters of the war and get them back into the air; many of the aircraft powered by V-1710s are flying with freshly overhauled engines again. The reliability, maintainability and availability of the engine prompted others to use it as a propulsion system for aircraft for which airworthy copies of the original engines are no longer available. Examples of this are a series of newly built Russian Jak-3 and Jak-9 and ambitious projects such as replicas of the Douglas World Cruiser or the Focke-Wulf Fw 190D "Long Nose" by the German Flug Werk GmbH .

Technical specifications

V-1710-85 :
Parameter Data
Type    Liquid-cooled 12-cylinder V-engine with mechanical supercharger, some versions with turbocharger.
drilling    5.5 inch ( inch ), corresponding to 139.7 mm
Hub    6 inch (152.4 mm)
Displacement    1710 cubic inches ( cubic inches ), equivalent to 28 liters
Dry weight    655 kg
Valve train    four valves per cylinder , sodium-cooled exhaust valves , one gear-driven overhead camshaft per cylinder bank
Loader    single-stage centrifugal loader with a diameter of 260 mm and 15 blades
Carburetor    Bendix Stromberg with automatic mixing ratio control
lubrication    Dry sump lubrication with one pressure pump and two return pumps
Cooling system    liquid-cooled with 70% water and 30% ethylene glycol , overpressure
power    988 kW (1343 hp) at 3300 min -1
Liter output    35.3 kW / l
compression    6.65: 1
Mass-performance ratio    1.51 kW / kg

variants

  • V-1710-A 2 copies
    • V-1710-A1 prototype for the Navy, 795 kW (1080 hp) at a speed of 2480 min −1 at sea level, compression ratio 5.88: 1, for 87 octane fuel
    • V-1710-A2 Prototype for the Fliegerkorps, 787 kW (1070 PS) at a speed of 2800 min −1 at sea level, compression ratio 5.75: 1, for 92 octane fuel
  • V-1710-B 3 copies
  • V-1710-B2R - V-1710-B4R for airships, 690 kW (940 HP) at a speed of 2400 min −1 at sea level, discontinued after the loss of the USS Akron and USS Macon , direction of propeller rotation reversible
  • V-1710-C 2582 copies
  • V-1710-D 44 copies
  • V-1710-E 18,998 copies
    • V-1710-E2 or V-1710-17 Bell XP-39
    • V-1710-E? or V-1710-31 Bell YP-39
    • V-1710-E4 or V-1710-35 Bell P-39C / D / F / G , 846 kW (1150 PS) at a speed of 3000 min −1 at sea level
    • V-1710-E? or V-1710-39 XP-39B
    • V-1710-E? or V-1710-49 XP-39E
    • V-1710-E? or V-1710-59 Bell P-39J
    • V-1710-E? or V-1710-63 Bell P-39L-Bell P-39F2
    • V-1710-E? or V-1710-83 Bell P-39M
    • V-1710-E? or V-1710-85 Bell P-39N
    • V-1710-E11 or V-1710-93 P-63A
    • V-1710-E22
    • V-1710-E27 or V-1710-93 Bell XP-63H
  • V-1710-F 47,660 copies
    • V-1710-F2R / L Lockheed P-38 , 864 kW (1150 PS) at a speed of 3000 min −1 at sea level
    • V-1710-F3R / L or V-1710-39 , for the NA-73X , NA-73 , NA-83 and the NA-91
    • V-1710-F5R / L or V-1710-49 / 53 P-38F
    • V-1710-F10R / L or V-1710-51 / 55 P-38G
    • V-1710-73 P-40K
    • V-1710-F15R / L or V-1710-75 / 77 P-38K , 1048 kW (1425 PS) at a speed of 3000 min −1 at sea level
    • V-1710-F17R / L or V-1710-89 / 91 P-38H / J , 1692 kW (2300 HP) at a speed of 3000 min −1 at sea level
    • V-1710-F20R or V-1710-81 NA-99 and P-40E
    • V-1710-F21R or V-1710-87 North American NA-97 Mustang / Invader
    • V-1710-F26R or V-1710-99 P-40N
    • V-1710-F30R / L or V-1710-111 / 113 P-38L
    • V-1710-F31R or V-1710-115 P-40N
    • V-1710-F32R / L or V-1710-119 /?
  • V-1710-G 763 copies
    • V-1710-G6R / L or V-1710-143 / 145 North American P-82E / F , 1618 kW (2200 PS) at a speed of 3200 min −1 at sea level

See also

literature

Matthias Dorst: All American Engine. Allison V-1710. In: Klassiker der Luftfahrt, 01/2018, pp. 50–57.

Web links

Commons : Allison V-1710  - Collection of Images, Videos, and Audio Files