Awesome...Mosquito with 57mm autocannon.

THE AIRCRAFT GUN

The RAF then became interested in fitting the Molins Gun in the de Havilland Mosquito, to form an airborne anti-tank weapon to replace the Hurricane IID which had been equipped with a pair of Vickers 40mm Class S guns.

The aircraft was duly developed as the Mosquito FB Mk XVIII, popularly known as the "Tsetse", but by this time the RAF had lost interest in the anti-tank gun role so the aircraft were brought into service by Coastal Command for anti-ship (and specifically anti-U-boat) purposes. The Tsetse, of which about thirty were built, served with No.248 Squadron during 1944 and is credited with sinking a U-boat.

Perhaps its most remarkable achievement occurred during an anti-shipping strike, when one Tsetse became involved in a melee with defending Luftwaffe aircraft. A Junkers 88 was careless enough to fly in front of a Tsetse, which promptly fired its big gun and demolished the Ju 88 with one shot!

The Molins Gun, which was technically known to the RAF as the "QF 6pdr Class M Mark I with Auto Loader Mk III" was based on the long-barrelled (50 calibre) gun. The gun weighed 487 kg (635 kg with autoloader) and was fully automatic, with a rate of fire of about 55 rounds per minute. The ammunition supply in the autoloader consisted of 21 rounds, held in five racks of unequal length, plus two additional rounds in the feedway. The rounds in each rack were fed by a combination of gravity and a spring-loaded arm and each rack was moved into place in turn by an electric motor. The gun normally used the plain AP shot (that is the only one shown in photographs), so had a high muzzle velocity of 890 m/sec (2,920 fps). Against U-boat hulls, it was calculated that it would be able to penetrate the hull when striking at an angle of 45 degrees or more, at a range of about 1400m, even through 60cm of water. The gun/aircraft combination was extremely accurate, achieving a hit rate in training of 33% against tank-sized targets - compared with 5% for rocket projectiles. The Tsetse was eventually withdrawn from service when the RAF decided to use rocket projectiles for such roles because, despite their relative lack of accuracy, these were more suited to a variety of purposes and could easily be fitted, or removed, as required.

The Molins Gun in the Mosquito FB Mk XVIII was tested in the USA in 1945, in comparison with the nearest US equivalent, the manually loaded 75mm AN-Mk 5 in the PBJ-1H. This comparison was more valid than the difference in calibre might suggest, for the 75x350R ammunition used in the American gun (the same as was used by the M4 tank gun in the Sherman) was about the same overall size as the 57x441R, and the 6pdr and 75mm tank guns were effectively interchangeable in the later British tanks.

The Molins Gun impressed the Americans with its performance and reliability and was considered superior to the 75mm as it could achieve a much higher rate of fire. It was noted that fairly violent evasive action and 2.5 positive Gs did not cause stoppages - which could not be said for manual loading!

The Americans recommended that the Molins autoloader could be considered as suitable not just for conventional guns but also for recoilless weapons and spin-stabilised rockets.

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Matt308 said:

What was most striking was the inherent inaccuracy in the video of most of the rocket firings. They missed by 300-800ft in most salvos. Wonder what the strike percentage was on a per sortie basis.

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Tony Williams said:

"]"In contrast, one direct hit with a bomb or 60 lb RP meant certain destruction for the heaviest tank. However, their accuracy left a lot to be desired. Even under practice conditions, the hit rate for the RPs against tanks was no better than 5%. This was graphically illustrated by a demonstration put on by Typhoons against a captured Panther tank placed in the middle of an open field, helpfully painted white with large red crosses on it to make sure the pilots could see it. Of the 64 RPs fired (launched in a typical steep dive at ranges of 750-900 m), only three hit the tank. In battle, RP accuracy was considerably worse than this, with the official British calculation of hit probability against a single tank being 0.5% (in other words, 200 RPs had to be fired for each hit). Furthermore, some 20 – 30% of RP warheads failed to explode.

This fall in accuracy experienced in action may be attributed to the curious trajectory of the RP, which first dropped below the line of sight and then accelerated as the rocket motor took effect before it dropped again. Because of this it was generally desirable to fire them at a range of between 900-1,800 m. They were also very susceptible to side winds, with a mere 15 km/h wind being enough to miss the aiming mark by nearly 5 m, and the aircraft had to be absolutely steady at the instant of launching. This meant that a pilot needed a very cool and calculating head to ensure reasonable accuracy, something that was difficult to achieve in the heat of battle. It is worth noting that high-velocity cannon did not suffer from this problem, so would have experienced a much less significant fall-off in accuracy under combat conditions. RP accuracy was helped to some extent late in 1944 by the introduction of the modified Mk.IID gyro sight with calibrations suited to the RP. This presumably accounted in part for a measured improvement in the average RP miss distance between 1944 and 1945, from 57 m to just under 40 m.

The greatest accuracy was achieved in a near-vertical dive as this minimised the trajectory quirks, but this left the Typhoon visible to the usually accurate light FlaK, so many pilots preferred to attack at tree-top height, firing at distances as close as 500 m. This is curious given that theoretical British studies of different attack angles concluded that a low level (less than 30 m altitude) attack was eight times as dangerous in terms of exposure to AAA as a sixty-degree dive, but it is possible that a very low approach, using terrain, trees and buildings to mask the view of the AA gunners, might have had advantages."[/COLOR][/INDENT]

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CHARLES BRONSON ,

DO YOU HAVE PHOTOS OF MOSQUITOS WITH MOLLINS CANNON, MACHINES GUNS AND ROCKETS ?

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