Tuesday, March 17, 2015

Soviet V-1s

Eighteen months after the first V1 attack on London the NKAP top brass (and probably the Soviet military leaders as well) did an 'about face' on their attitude to guided weapons The aforementioned engineers Nikol'skiy and Chachikian wrote to the Soviet government; this letter prompted the preparation of a draft directive by the State Defence Committee (GKO - Gosaodarsfvennyy komfret oborony) ordering the establishment of the OKB-100 design bureau within the MAP system with a prototype construction shop and flight test facility based on the (former) plant No.23 In Leningrad. The new enterprise was tasked with developing and building radio-controlled and unguided gliding torpedoes and radio-controlled guided bombs. At about the same time the task of developing an indigenous equivalent of the German 'buzz bomb' was assigned to the Central Aero Engine Institute (TslAM - Tsentrahl'nyy institoot aviatsionnovo motorostroyeniya).

Work on pulse-jet engines at TslAM had proceeded since 1942 under the guidance of Vladimir Nikolayevich Chelomey. It took him two years to build and test the first workable Soviet pulse-jet. When the Soviet government learned of the missile attack on London, Aleksey I. Shakhoorin (the then People's Commissar of Aircraft Industry), Air Marshal A. A. Novikov (the then Commander- in-Chief of the Red Army Air Force) and V N. Chelorney were summoned to the Kremlin for a GKO briefing and tasked with developing new pilotless aerial weapons systems. The appropriate GKO directive appeared soon afterwards.

The advanced development project of Chelomey's winged missile powered by a D-3 pulse-jet and designated 10Kh was completed in the late summer of 1944. On 19th September of that year V. N. Chelomey has appointed Chief Designer and Director of NKAP plant No.51 - the former prototype construction shop of the late 'Fighter King' Nikolay N. Polikarpov.

Development of the 10Kh was accelerated by the delivery of incomplete V1 'buzz bombs' (or their wreckage) from Great Britain and Poland; yet, while bearing a strong resemblance to the V1, the 10Kh was not a direct copy of it. For instance, to speed up the production entry of the Soviet missiles’ AP-4 autopilot the specialised OKB-1 design bureau under V. M. Sorkin made maximum use of off-the-shelf components from production Soviet aircraft instruments. By early 1945 the first prototype 10Kh had been completed and the D-3 engine had passed official bench tests at TslAM The first production missile left the assembly line as early as 5th February 1945; seventeen of the nineteen missiles manufactured by plant No 51 were cleared for flight tests, the remaining two being retained by the plant as pattern samples.

Three Petlyakov Pe-8 long-range bombers and two Yermolayev Yer-2 long-range bombers were fitted out with racks for carrying and launching the 10Kh missile. The smaller and cheaper Yer-2 was considered a better alternative, but the Charomskiy ACh-30B diesels of the first Yer-2 involved suffered from the high ambient temperatures of Central Asia where the test range was, the shortfall in engine power was so severe that the bomber could not become airborne with the missile in place. Eventually the engines went unserviceable altogether and from then on only the Pe-8s were used in the tests at that location; the other Yer-2 was operated in the cooler climate or the Moscow Region.

By the end of 1944 the development of the D-3 pulse engine that propelled the 10Kh was at the prototype stage and the first production 10Kh was ready on February 5, 1945. As no launching ramps had been constructed, the first test was an air launch from a Petlyakov Pe-8 heavy bomber on 20 March 1945, near Tashkent. By 25 July 1945 66 missiles had been launched, of which 44 transitioned to autonomous flight, 22 of these reaching the range target and 20 maintaining the required heading. A batch of improved 10Kh (Izdeliye 30) were constructed with wooden wings, and 73 more air launches were performed in December 1948. A ground launched variant called 10KhN was also tested in 1948, which used rocket-assisted takeoff from a ramp.

The purpose of the first tests was to determine the feasibility of dropping the 10Kh missiles from a plane in flight and, about 100 meter below the plane, ignite the pulse jet, but only 6 out of 22 missiles did so correctly. The second series of tests were on corrected faults in the missiles, allowing a success of 12 out of the 22 missiles launched. The final tests were conducted to determine the precision (6 of 18 missiles launched impacted the target) and effectiveness (from 4 missiles, 3 detonated successfully) of the missiles.

In the spring of 1945 NWP plant No.125 joined forces with other plants to launch production of the 10Kh in accordance with the manufacturing documents supplied by Chelomey's plant No.51. A total of 300 had been built before production was halted due to the end of the hostilities.

In the meantime the Chelomey OKB brought out three models of more powerful pulse-lets based on the D-3; these were the D-5 rated at 420-440 kgp (925-970 Ibst), the 600-kgp (1,320-lbst) D-6 and the 900-kgp (1,980-lbst) D-7.The D-5 delivered 425 kgp (937 lbst) during bench tests In November 1945 Back in 1944 Chelomey had begun design work OR the 14Kh winged missile powered by this engine. The greater engine thrust and the more aerodynamically refined fuselage were expected to give this weapon a 130-150 km/h (80-93 mph) higher cruising speed as compared to the 10Kh; the new engine's higher weight was offset by a weight saving thanks to changes in the wing design (the wings were smaller, featuring pronounced taper).

Teaming up with plant No.456, the Chelorney OKB's experimental shop manufactured a batch of twenty 14Kh missiles in 1946. Ten of them underwent flight tests at a target range between 1st and 29th July 1948, a Pe-8 bomber acting as the launch platform. Six of these missiles featured standard rectangular wings, while the other four featured reinforced wings of trapezoidal planform: the wings were of wooden construction both cases. The trials showed that the 14Kh met the specifications; the trapezoidal-wing version attained a speed of 825 km/h (512 mph) or even higher on a 100km (62-mile) stretch, exceeding the target figure by 10%. On the other hand, the wooden wings were not strong enough; several wing failures were experienced and the structure needed to be reinforced before the missile could enter service.

The D-6 passed its official manufacturer's tests In October 1946 with good results. Two months later it bettered the specified thrust figure by 110 kgp (240 Ibst) when run on a bench during state acceptance trials. This allowed plant No.51 to develop a projected winged missile of 7,000 kg (15,430 Ib) calibre powered by two D-6 engines a 1946.

In 1945 the Chelomey OKB had completed the advanced development project of the 16Kh winged missile. At first this was basically the airframe of the 10Kh mated to a D-6 engine; later, however, the project was significantly revised to feature two D-3 englnes on outward-canted pylons. The Tu-2 bomber was chosen as the delivery vehicle.

In early 1947 plant No.51 (the Chelomey OKB) was tasked with developing a whole series of winged missiles, the air-launched 16Kh, the naval 15Kh and 17Kh to be launched from surface ships, and the 18Kh.  Very soon, however, the government had to curb its appetite, limiting the order to the revised 16KhA Priboy (Surf) missile and the 10KhM target drone (M = mishen' - target).

    The initial production version of the V-1 reverse engineered look-alike, powered by a single Chelomey D-3, reverse engineered Argus As014.
10Kh Izdeliye 30
    Improved version with wooden wings.
    A ground launched version using rocket assisted take off gear to boost the missle up a launch ramp.
    Further development with revised wings of several configurations and structural material, powered by single Chelomey D-5.
    An outgrowth of the Kh14 powered by a single Chelomey D-6.
    A ship launched version.
    Experimental missiles using Kh10 airframes with single Chelomey D-6 engines, later tested with two Chelomey D-3 engines mounted side by side on V-configured pylons on the aft fuselage and extended tailplanes with rectangular fins and rudders at the tailplane tips.
        A ship launched version.
    Further development of the 10Kh series of cruise missiles.
Gliding bomb
    An unpowered gliding bomb was also derived from the 10Kh featuring a twin tail similar to the 16Kh in addition to a central fin, as well as a jettisonable undercarriage.

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