Aircraft of the version that followed the Mk.IA, the Typhoon Mk.IB, had armament that consisted of four 20 mm British Hispano Mk.I magazine-fed cannons, with 75 rounds each.
The seepage of exhaust gases from the engine into the pilot's cockpit became a serious problem for production Hawker Typhoon fighters and even caused some disasters. Although the sealed partition between the cockpit and the engine compartment was improved and the exhaust pipes of the engines were made longer, this problem was never entirely solved, and Typhoon pilots had to fly without taking off their oxygen masks.
Another problem was the low reliability of Napier Sabre Mk.IIA engines at the initial stage of operation. The engine used to overheat, and it could jam when the aircraft climbed. Cases when the engine caught fire on takeoff were also frequent. It was only by the middle of 1943 that engineers managed to completely overcome these problems and bring the engine's reliability to an acceptable level.
During the course of the Typhoon's intensive combat operation, the pilots discovered the insufficient strength of the tail section of its fuselage. Several disasters occurred when planes, just like lizards when their life is in danger, dropped off their tails completely when they pulled out of a dive. As an interim measure, reinforcing straps were fitted across the joint of the tail section and the fuselage. Subsequently it was found out that the disasters were caused by the elevator flutter which occurred at a relatively low speed. The flutter itself was caused by the fatigue failure of the small ring holding the balance weight assembly. The flutter could also lead to a failure of the tailplane spar, so it urgently had to be reinforced as well.
Back in early 1942, Hawker Aircraft had embarked on equipping the Typhoon with external fittings. At first they added drop tanks, increasing the aircraft's flight range. Then the suspension of two 500 lb (227 kg) bombs was tested, and later the same was repeated with heavier American 1,000 lb (454 kg) bombs.
An important step in enhancing the Typhoon's firepower was equipping it with rocket weapons. By the end of 1942, 5-inch (76 mm) unguided missiles equipped with a 27 kg warhead were produced in large quantities. They were inexpensive and easy to manufacture and proved reliable enough, although they were not characterized by a high strike accuracy. The Typhoon was equipped with eight guide rails for these rockets, four under each wing.
During 1943, air squadrons equipped with Typhoons were passed through maintenance bases one by one to receive bomb racks and rocket guide rails.
In October 1942, the first combat deployment of the aircraft took place when the planes were used to patrol over the English Channel. From November 1942 on, Typhoons were used as fighter bombers to hit ground targets on the Continent.
In the skies over Western Europe, the Royal Air Force was switching from a defensive strategy to offensive operations. The Typhoon, with its powerful armament, was designed to replace Hurricane fighters in operations against the German transport infrastructure.