The next version to enter mass production was the Spitfire Mk.IX. The main improvement of this version being the Merlin 61 two-staged two-speed supercharged engine allowing for high altitude operations to be commenced. The engine had been tested in the lone Mk.III Spitfire for use in the Wellington and found to be quite functional at high and low altitude. The Mk.IX was pushed forward as an interim aircraft whilst the Mk.VII and Mk.VIII were being developed, as a direct approach to counter the Fw190 which had outclassed the Spitfire Mk.V. Although using the Mk.V basic airframe with very little improvements, the Mk.IX was superior in performance beyond expectation due to the new Merlin 62 engine. All trials and tests were so positive that the type was approved as the next major production model as the Mk.VII and Mk.VIII would not be available until early 1943.
The Mk.IX was produced in vast numbers, almost equivalent to the Mk.V. and was vastly superior in speed and performance than its counterpart despite having none of the improvements or modifications installed on the Mk.VII and Mk.VIII. The Mk.IX was the first to use the ‘d’ and ‘e’ wing varieties. Its high-altitude performance above 20,000ft was exceptional. The Mk.IX was the first to intercept a Junkers Ju86 high altitude bomber at 40,000ft in September 1942. The more powerful Merlin 63 was phased in during 1943 and a LF Mk.IX version using the Merlin 66, aka Mk.IXb, was developed with a top speed of 404mph. Over four thousand of these were built. A specific HF Mk.IX with the Merlin 70 specialised engine was introduced in March 1944.
Late production Mk.IX’s included the bubble canopy designed for the late production Mk.VIII with the cut back fuselage and clipped wing. Most of these were used post war in South Africa and Korea.
Many Mk.IX’s were converted to Photo Reconnaissance(PR) and Fighter Reconnaissance(FR). All the PR Mk.IX aircraft were stripped of all armament and painted an overall PRU blue and used the d wing variant. The FR types were armed and used for low altitude “Dicing” missions in army support. 16 Squadron famously painted their aircraft a light pink colour, surprisingly good camouflage at dawn and dusk under cloud cover, to photograph the Arnhem area before Market Garden.
In all 5,656 Mk.IX were built, a staggering number since it was only meant to be a stand-in. Production ceased in April 1945.
There are many airworthy Mk.IX’s around the world as well as many on static display. The UK has many of these. The airworthy are as follows.
Spitfire F Mk.IXc LZ842 flying with various squadrons during the Malta campaign.
Spitfire LF Mk.IXc MH415
Spitfire LF Mk.IXb MH434 owned by the Old Flying Machine Company, Duxford.
Spitfire LF Mk.IXc MK912 built in 1944 it flew with the RAF during and post war until being damaged in 1953. It was restored in 2000 to airworthy condition.
Spitfire LF Mk.IXc ML417 built 1944 and is with The Fighter Collection.
Spitfire HF Mk.IXe RR232 built in 1943 it is owned by Spitfires.com and based at Goodwood Aerodrome.
Spitfire HF Mk.IX TA805 based at Biggin Hill. It flew with the SAAF and recovered from a scrap yard in the 1990’s and returned to England.
There are several T.9 two-seater trainers, in essence a Mk.IX fitted with an extra cockpit which were produced after WW2, providing joy flights from Duxford and other locations throughout the UK.
