[CrankyBulletcup]

BF109G-2

The rack and internal fuel lines for carrying a 300 L (80 US gal) drop-tank were widely used on G-2s, as were the underwing 20 mm MG 151/20 cannon gondolas. Several G-2s were fitted with the ETC 500 bomb rack, capable of carrying one 250 kg (550 lb) bomb. The final G-2 production batches built by Erla and Messerschmitt Regensburg were equipped as tropical aircraft (often referred to as G-2 trop), equipped with a sand-filter on the front of the supercharger intake and two small, teardrop-shaped metal brackets on the left side of the fuselage, below the cockpit sill. These were used as mounts for specially designed sun umbrellas (called Sonderwerkzeug or Special tool), which were used to shade the cockpit.

BF109F-4

The 1,350 PS (1,332 hp, 993 kW) DB 601E was used in the F-3 and F-4 model together with a VDM 9-12010 propeller with broader blades for improved altitude performance. The DB 601 E was initially restricted to 1,200 PS (1,184 hp, 883 kW) at 2,500 rpm; however, the full rating of 1,350 PS at 2,500 rpm was cleared for service use by February 1942. The DB 601 E was able to use 87 octane "B-4" aviation fuel, despite its increased performance; while the earlier DB 601N ran on 100 octane designated as "C-3" by the Luftwaffe.

Only 15 examples of the F-3 are believed to have been produced by Messerschmitt Regesnburg between October 1940 and January 1941. Like the F-1, the F-3 was armed with the 20 mm MG-FF/M and two 7.92 mm (.312 in) MG 17s.

From the F-4 onward, the new 20 mm Mauser MG 151/20 with 200 rounds was used as the motorkanone. The first F-4s reached frontline units in June 1941. Production lasted exactly a year between May 1941 and May 1942, with 1,841 of all F-4 variants produced. Some of the later models were capable of mounting two 20 mm MG 151/20 cannons under the wing in faired gondolas with 135 rpg. These were designated F-4/R1 and 240 of them were produced by W.N.F. in the first quarter of 1942. This optional additional armament was standardized as field kit for later G and K series. A special high-altitude variant, the F-4/Z featuring GM-1 boost, was also built with a production run of 544 in the first quarter of 1942 and saw extensive use. Finally, the Erla factory produced 576 tropicalized F-4 trop in the first half of 1942.

With its initial engine rating of 1,200 PS, the maximum speed of the F-4 (and F-3) was 635 km/h (394 mph) at rated altitude; and with the clearance of the full rating of 1,350 PS, maximum speed increased to 670 km/h (420 mph).


Spitfire Mk IX

Mk IXs. Different wings, featuring a variety of weapons, were fitted to most marks; the A wing used eight .303 in (7.7 mm) machine guns, the B wing had four .303 in (7.7 mm) machine guns and two 20 mm (.79 in) Hispano cannon, and the C or Universal Wing could mount either four 20 mm (.79 in) cannon or two 20 mm (.79 in) and four .303 in (7.7 mm) machine guns. As the war progressed, the C wing became more common. Another armament variation was the E wing which housed two 20 mm (.79 in) cannon and two .50 in (12.7 mm) Browning machine guns.

Minor note:

Due to a shortage of Brownings, which had been selected as the new standard rifle calibre machine gun for the RAF in 1934, early Spitfires were fitted with only four guns, with the other four fitted later. Early tests showed that while the guns worked perfectly on the ground and at low altitudes, they tended to freeze at high altitude, especially the outer wing guns. This was because the RAF's Brownings had been modified to fire from an open bolt; while this prevented overheating of the cordite used in British ammunition, it allowed cold air to flow through the barrel unhindered. Supermarine did not fix the problem until October 1938, adding hot air ducts from the rear of the wing mounted radiators to the guns, and bulkheads around the gunbays to trap the hot air in the wing. Red fabric patches were doped over the gun ports to protect the guns from cold, dirt and moisture until they were fired. Even if the eight Brownings worked perfectly, pilots soon discovered that they were not sufficient to destroy larger aircraft. Combat reports showed that an average of 4,500 rounds was needed to shoot down an enemy aircraft. In November 1938, tests against armoured and unarmoured targets had already indicated that the introduction of a weapon of at least 20 mm calibre was urgently needed.

In June 1939, a single Spitfire was fitted with a single drum-fed Hispano in each wing, an installation that required large blisters on the wing to cover the 60-round drum. The cannons suffered frequent stoppages, mostly because the guns were mounted on their sides to fit as much as possible of the magazine within the wing. In January 1940, PO George Proudman flew this prototype in combat, but the starboard gun stopped after firing a single round, while the port gun fired 30 rounds before seizing. If one cannon seized, the recoil of the other threw the aircraft off aim. Nevertheless, 30 more cannon-armed Spitfires were ordered for operational trials, and they were soon known as the Mk IB, to distinguish them from the Browning-armed Mk IA. In June 1940, they were delivered to No. 19 Squadron. The Hispanos, though, were still so unreliable that the squadron requested an exchange of its aircraft with the older, but Browning-armed, aircraft of an operational training unit. But in August, Supermarine had perfected a more reliable installation of the cannons with an improved feed mechanism and four .303 in outer wing panels. The modified fighters were then delivered to 19 Squadron.