BK 27

Tony Williams

You will find these articles on my website of interest; they both contain photos of the 40mm ammo:

http://www.quarry.nildram.co.uk/tankbusters.htm

http://www.quarry.nildram.co.uk/sgun.htm on the S gun+Littlejohn

The S Gun rounds are rare and very expensive on the odd occasion when one comes on the collectors’ market.

Tony Williams: Military gun and ammunition website and discussion
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I agree that TSR2 would not have become obsolete, provided that its sensors and other avionics were kept up to date. It was not dissimilar to the F-111 bomber (which it was cancelled in favour of), which only recently left US service and is still in service in Australia. For the long-range strike role it was I think a better design than the Tornado (which was too small).

However, I think that the main reason for deploring its cancellation was the blow it struck against the British aircraft industry. It was one of the key decisions which seriously damaged the UK’s ability to design and develop military aircraft.

Tony Williams: Military gun and ammunition website and discussion
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The Rafale was a political plane. The French were originally part of the Eurofighter consortium but parted company and went their own way (IIRC they demanded design leadership, despite not being the biggest customer, and were told where to go – so they went).

So the Rafale was built in a fit of national pride, to show they could do it. So, of course, the French Navy’s new carrier had to use a naval version of the plane and therefore had to be CTOL. There wasn’t the chance of a snowball in Hades that France would buy an American plane instead.

The amount of money wasted by European countries on building their own kit instead of standardising is colossal. Even joint projects like Eurofighter cost the Earth because of the national haggling over build shares, duplicated production lines etc.

However, the answer IMO is not to buy American (though their politicians and industry would love that) but to adopt sensible pan-European acquisition agreements. Airbus shows how Europe can compete successfully, if it has a mind to.

Tony Williams: Military gun and ammunition website and discussion
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The cannons also had a protective sheath (rather resembling a large contraceptive!) pulled over them for pretty much the same purpose.

I thought it WAS a contraceptive!

Tony Williams: Military gun and ammunition website and discussion
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The Mauser BK 27 was selected by both of the JSF contenders. However, after the F-35 had won the competition, GE was given the contract for installing the gun and came up with a proposal to fit the GAU-12/U instead, made by – guess who?

The argument was that the GAU-12/U was cheaper, and the gun and ammo were already in USMC service (as if they hadn’t known that from the start…). However, all of the publicity surrounding the inital selection of the Mauser emphasised that it was the best and most cost-effective weapon. The most charitable explanation I have heard for the switch to the GAU-12/U is a suggestion that the process of ‘Americanising’ the BK 27 proved to be much longer and more expensive than had been expected.

Tony Williams: Military gun and ammunition website and Discussion forum

Hurricanes very nearly saw a much more active role – this is from: ‘Flying Guns – World War 2: Development of Aircraft Guns, Ammunition and Installations 1933-45’ by Emmanuel Gustin and myself:

“The IID was not the only Hurricane to carry the 40 mm S gun. The Hurricane IV, of which over five hundred were built, was introduced in 1943 as a specialised ground attack variant. A more powerful engine enabled more armour to be fitted and it had a “universal wing”, designed to take various armament options including the S gun or rocket projectiles (RPs); the changeover could be made by five men in about forty minutes. Most saw service overseas but three squadrons based in England (Nos. 137, 164 and 184) were equipped with this aircraft.

Official British reports during 1943 concerning the effectiveness of the armament options for the Hurricane IV make interesting reading. The 40 mm gun was seen as the precision weapon, usable against smaller targets such as locomotives and tanks, while the RPs were thought to be more effective against shipping. It was recommended that all Hurricane IVs should normally be issued fitted with the S gun, with conversion kits for RPs provided, and that squadrons should employ both variants, with different flights being equipped with RPs or S guns. Operations were conducted by 11 Group over France and against coastal shipping, and both guns and RPs were evidently considered satisfactory.

In June 1943 the RAF’s order of preference in weapons for use against tanks was given as: 1st 40 mm S gun; 2nd 20 mm cannon with Mk III AP ammunition; 3rd RP with 25 lb AP head; 4th RP with 60 lb HE head; 5th .50″ Browning HMG; 6th 9 lb AT bomb. Only the first three of these were considered to be serious anti-tank weapons. Some comment on these preferences is necessary. The 20 mm AP Mk III, as mentioned in Chapter 1, was a tungsten-cored round of considerable performance which was, in the end, not adopted. The RP with 25 lb AP head could penetrate 70-80 mm, which compensated to some extent for its lack of accuracy. The RP with 60 lb HE head was discounted against tanks as it could only penetrate 25 mm, but this assessment rather underestimated the cataclysmic effect of detonating such a large charge against a tank.

The 9 lb AT bomb, jovially known as “Puffball”, used a squash-head rather than a HEAT design and a fighter-bomber was expected to carry twenty-four of them, to be released in one diving pass at low altitude. Despite the success of similar (but smaller) Soviet and German weapons, Puffball proved unsatisfactory due to sympathetic detonations in mid-air (the explosion of the first hits setting off the others) and significant damage from blast and debris being suffered by the carrying aircraft. The 40 mm S gun, 20 mm AP Mk III and 25 lb AP were all considered capable of dealing with the German Mk IV tank and it seemed that the S gun-equipped Hurricane Mk IV would have a part to play in the forthcoming invasion of Europe. Despite this, all Hurricanes were withdrawn from European service in March 1944, just three months before D-day.”

Tony Williams: Military gun and ammunition website and Discussion forum

The .303 was one third of the weight of the .50 and fired 60% faster, so for the same weight of armament could put out almost five times as many bullets.

HOWEVER – planes in WW2 were too tough, even without armour plate, for the .303 to do much damage to. This is from ‘Flying Guns – World War 2: Development of Aircraft Guns, Ammunition and Installations 1933-45’ by Emmanuel Gustin and myself, concerning British tests of .303 and 7.92mm armour-piercing ammunition:

“The test then changed to shooting at the rear of the long-suffering Bristol Blenheim at the same distance, involving penetrating the rear fuselage before reaching the 4 mm armour plate protecting the rear gunner, which was angled at 60º to the line of fire. The results in this case were reversed; 33% of the .303″ rounds reached the armour and 6% penetrated it. In contrast, only 23% of the 7.92 mm bullets reached the armour, and just 1% penetrated. The British speculated that the degree of stability of the bullets (determined by the bullet design and the gun’s rifling) might have accounted for these differences.”

The .303 ‘de Wilde’ incendiary bullet performed quite well, but even so it was not surprising that many German bombers made it back to base despite being riddled with .303 bullets.

In comparison, the .5 remained effective throughout the war; although it wasn’t as destructive as the 20mm cannon it was good enough.

The only purpose for which the .303 was better was strafing troops out in the open, because of the higher number of bullets being fired.

For more details on WW2 aircraft armament evaluation, see: http://www.quarry.nildram.co.uk/WW2guneffect.htm

Tony Williams: Military gun and ammunition website and discussion
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