Allison V-1710

The Allison V-1710 is an engine of aviation, the only one of American design to have a configuration out of V and a liquid cooling for the period of the Second world war. Because of preference, before war with the USA, for the configurations out of star and the Turbocompressor S, it never succeeds in reaching the performances and the reliability of the foreign engines, and American industry finally had to resort to the production under license of the British engine Rolls Royce Merlin to equip its fighter plans for the combat with high-altitude. Allison equipped nevertheless with very many planes like the Lockheed P-38 Lightning, the Bell P-39 Airacobra and the Curtiss P-40 Warhawk and known a very important production with 70033 specimens carried out of the August 13rd 1931 with the June 2nd 1948 with the factory of Indianapolis. After the war, he knew also a career like engine of race, in particular of Hydroptère S.

History

Founded by James A. Allison in 1915 to build engines and cars with Indianapolis beside the road racing set that it had also created, the Allison company was not long in being made known in the aeronautical field. At the request of Allison, Norman Gilman, entered the company in 1917 as chief technical officer, takes part indeed, at the request of Allison, the design of the engine Liberty of 400 horses. In 1927 Gilman poses patents on an improvement of the engine what enables him to constitute funds for studies utltérieures. After the death of James Allison in 1928 and the repurchase of the company by General Motors in 1929, Norman Gilman is named president, function which it cumulates with that of chief technical officer. It decides also the study, on its private funds, of a new engine with liquid cooling of 1000 horses (750 kw) to remlir the future needs for the US Army and US Navy.

The stress is laid especially on the possibility of using the base of the engine for various uses and the design, the system of reduction and the compressor were thought to be easily exchanged. Prototype V-1710-A of 1,010 lbs carried out a first test on bench in 1931 delivering 650 horses with 2400 turns per minutes. The compressor with a mutiplication of 7,3 compared to the camshaft had then passed to a multiplication of 8,0 and in 1932, the engine makes a success of a fifty hours test during which it provides 750 horses, always with 2400 turns per minutes.

The US Navy, although she prefers the radial engines for her planes, then expressed its interest for V-1710 with an aim of equipping its Dirigeable S. She supervised the development of a version deprived of compressor but equipped with two Carburateur S between the two lines of Cylindre S. This engine was also equipped with a system of inversion with propeller enabling him to pass from the full power in a direction to the same power in the direction opposed in less than eight seconds. This engine, the V-1710-B, was designed to equip airships USS Akron and USS Macon. The program is however cancelled following the loss of the aircraft. The economic situation, following the Great depression, slows down the development so that the first engine in flight only the December 14th 1936 on Consolidated A-11A was tested.

In 1933, Norman Gilman engages Ronald Hazen which had worked at Fairchild with the design of the Ranger engine. In March 1936, this one becomes chief technical officer. Under its impulse, V-1710 is entirely reconsidered. The drawing of the rooms and the pistons was improved, as well as the valves to improve the mixture of the air and by the fuel, the diameter of the turbine of the increased compressor from 8,25 to 9,5 inches and the report/ratio of drive of the propeller are increased to 2 instead of 0,66, the compression ratio in the cylinders passes to 6. The engine passes 150 hours the lawful test of the Army. The April 23rd 1937, during the test, it provides 1000 horses, being the first engine to reach this power. Thereafter one could reach 6,65 and the number of revolutions of 3500 turns per minute, on the basis thus created. The new engine is proposed with the various American airframe manufacturers and meets a great success since it equips the majority with the planes engaged in the US Army Pursuit Contest . XP-37, the Lockheed XP-38 and Beautiful XP-39 with of V-1710 turbocompressés and XP-40 with a simple mechanical compressor. The US Army, at the end of the Thirties, strongly put on overfeeding by turbocompressor, which she thought of having to exceed the solutions by mechanical overfeeding in the near future. It was a bad choice because the material shortage like the Tungstène, necessary to alloys resistant at high temperature, and the difficulties of development prevent the mass production of Turbocompresseur S, which are then reserved for the bombers, considered to be priority. The fighter plans equipped with V-1710 were thus equipped with mechanical compressors but those suffered from a great delay compared to their European equivalents and the performances in altitude suffered from it. It is only towards the end of the war that the Allison engine profited from compressors more sophisticated on two floors and several speeds but those appeared not very reliable and V-1710 always suffered from failing performances in altitude.

On the other hand, very early in the war, Allison authorized the use of the engine in emergency mode, the engine providing then 1600 horses (1200 kw) instead of the 1150 (860 kw) envisaged. However the engine was to then be dismounted and inspected before any re-use. The lifespan of the engine increased during the conflict by 300 with nearly 1000 hours and the engine always profited from a good specific power with more than 1,6 kw per kilogram.

P-39 and P-40 were then carried out with many specimens and then absorbed most of the production of Allison. Only P-38, produced in more minor amounts, preserves its turbocompressors, which made a remarkable hunter in altitude of it. V12 equipped also the first series with the North American P-51 Mustang and with many prototypes like the Republic XP-47A, Curtiss XP-55 Ascender, Boeing XB-38, and Douglas XB-42 Mixmaster. During the war, the cost price of the engine fell from 25.000 to 8.000 Dollar S. After war, Allison was selected to equip 250 P-82E/F/G.

V-1710 also served in many races air, nautical and automobile, unquestionable exemplary optimized newcomer required nearly 4000 horses (3000 KW). The V-1710-G6, amongst other things, were used on Hydroptère S of the competitions Unlimited hydroplanes racing during which they built many world speed records on water. During the years 1990, of V-1710 were used to equip with the counterparts of hunters of the Second world war like the Yak-3UM and of the rebuildings.

Description and characteristics

Allison V-1710 is a V12 engine with liquid cooling of very traditional design. The two monoblocs groups of six cylinders are bolted with an angle of 60 degrees on the block containing the Vilbrequin. This last consists of parts in moulded Aluminum which separate on the level from the horizontal one. the two blocks of six cylinders are them also in two parts in aluminum moulded, a set of body and together of heads which imprison the steam jackets out of chilled steel. Inside the pistons forged out of aluminum push on rods out of steel which involve they even the crankshaft. This one has a coupling with each one of its ends, on which come to fix itself at before a whole of gears of reduction actuating the propeller and at the back a device of attenuation of the vibrations dynamic and hydraulic, which actuates the accessories located on the back of the engine. It can also be gone up in the two directions, which makes it possible to easily reverse the direction of rotation of the engine.

Each head of cylinder has two inlet openings inside V and two of exhaust towards the outside bored with 22,5° compared to the axis of the cylinder and closed by Soupape S out of alloy nickel-chromium (65% Nickel, 20% Fer and 15% Chrome) treated surfaces some with stellite (an alloy at base Cobalt) with a room interns containing Sodium to improve the evacuation of heat. The Soupape S are ordered by a single camshaft by group of cylinder, which involves to him even a tilting arm for each cylinder, acting directly on the tails of valve. The mixture supply is ensured by an injection pump Bendix Stromberg SD400B3 which takes into account the density of the mixture and the number of revolutions of the engine.

designation of the engine: Allison V-1710-G6

Provision: 12 cylinders out of V of 60°.

race: 152 mm

boring: 140 mm

rolled total: 28 Liter S.

ratio compression: 6,65 per 1.

mass: 707 kg

width:

length:

power on takeoff: 1250 ch (932 kw)

consumption:

step-up ratio of the propeller:

fuel:

Versions

The Allison engines gave rise to many derivatives, two designations cohabit, one of factory including/understanding a letter indicating the principal version and a figure, under version, and another known as of service created by USAAF including/understanding only one number.

V-1710-A 2 specimens.

V-1710-A1 or V-1710-2 , 1931, 650 ch with 2400 tr/min, fuel with octane number of 87, diameter harnesses compressing of 8,25 inches and report/ratio of drive 0,66:1 on the propeller, ratio compression 5,75.
V-1710-A2 or V-1710-1 , prototype for the navy gasoline with octane number of 92, ratio compression 5,88.

V-1710-B 3 specimens.
V-1710-B 2R or V-1710-4 , version for the airships of US Navy, not of compressor, reverser of direction of propeller.
V-1710-C 2582 specimens.

V-1710-C6 1936, 1000 ch with 2600 tr/min with the sea level, diameter harnesses compressing last with 9,5 inches and report/ratio of drive 2:1 on the propeller.
V-1710-11 XP-37
V-1710-19 XP-40
V-1710-21 YP-37
V-1710-C15 or V-1710-33 , for P-40, carburizing Bendix.

V-1710-D 44 specimens.
V-1710-D2 or V-1710-9 , version intended for the Beautiful Aircraft XFM-1 Airacuda, box of external reducer of propeller and propelling configuration.
V-1710-E version equipping P-39, P-63 and XB-42 with a whole of reduction for the external propeller with the engine, the tree being prolonged of 10 feet, 18.998 products.

V-1710-E2 or V-1710-17 , version with turbocompressor intended for the XP-39.
V-1710-E? or V-1710-31 , version with mechanical compressor intended for the YP-39A.
V-1710-E4 or V-1710-35 , version with mechanical compressor intended for the P-39C/D/F/G.
V-1710-E? or V-1710-39 , version with mechanical compressor intended for the XP-39B.
V-1710-E? or V-1710-49 , version with mechanical compressor intended for the XP-39E.
V-1710-E? or V-1710-59 , version with mechanical compressor intended for the P-39J.
V-1710-E? or V-1710-63 , version with mechanical compressor intended for the P-39L and P-39F2.
V-1710-E? or V-1710-83 , version with mechanical compressor intended for the P-39M.
V-1710-E? or V-1710-85 , version with mechanical compressor intended for the P-39N.
V-1710-E11 or V-1710-93 , compressing mechanics with two stage and two speeds, equipping P-63A
V-1710-E22
V-1710-E27 or V-1710-129 , turbo-copound, prototype for the XP-63H.

V-1710-F version equipping P-38, P-40 and P-51 with a whole of reduction for the propeller integrated into the engine, 47.660 products.

V-1710-F 2R /L or V-1710-27/29 , for P-38, rotation towards the line or left.
V-1710-F 3R or V-1710-39 , for the NA-73X, NA-73, NA-83 and NA-91.
V-1710-F 5R /L or V-1710-49/53 , for the P-38F, rotation towards the line or left.
V-1710-F 10R /L or V-1710-51/55 , for the P-38G, rotation towards the line or left.
V-1710-73 P-40K
V-1710-F 15R /L or V-1710-75/77 , version with turbocompressor for the P-38K, rotation towards the right-hand side or the left, injection water methanol ADI, gasoline with octane number of 115 and 145 with the ADI, 2300 ch with 3000 tr/min with the sea level.
V-1710-F 17R /L or V-1710-89/91 , version with turbocompressor for the P-38H, rotation towards the right-hand side or the left, injection water methanol ADI, gasoline with octane number of 115 and 145 with the ADI, 2300 ch with 3000 tr/min with the sea level.
V-1710-F 20R or V-1710-81 NA-99 (P-51A) and P-40E, 1200 ch au takeoff.
V-1710-F 21R or V-1710-87 NA-97 (A-36A), 1325 ch with 1000 Mr.
V-1710-F 26R or V-1710-99 P-40N, compressor on a speed and a floor, 1200 ch au takeoff, 1125 ch with 5274 Mr.
V-1710-F 30R /L or V-1710-111/113 , P-38L
V-1710-F 31R or V-1710-115 P-40N
V-1710-F 32R /L or V-1710-119/? , compressing mechanics with two stage and two speeds and intercooler.

V-1710-G new tree with cane, various configurations of overfeeding, 763 products including 750 G6.

V-1710-G 6R /L or V-1710-143/145 , rotation towards the right-hand side or the left, injection water methanol ADI, gasoline with octane number of 115 and 145 with the ADI, Bendix injection.

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