The first director of the newly renamed RAE was W. Sydney Smith, who had replaced Henry Fowler as head of the RAF in April 1918. With the new focus on research and development he brought about some reorganisation of the departments with some being established or changed to focus on specialist areas including aerodynamics, engines, physics, instruments, metallurgy, mechanical testing, chemistry and fabrics.

With the end of the First World War the RAE underwent a large reduction in staff and resources, with the numbers employed falling from 5,052 in November 1918, to 1,380 by the mid-1920s. There was a similar reduction in funding, with only 3.9% of the Air Estimate being allocated to the site in 1922, but research would continue to be conducted despite these difficulties.

In 1919 there was also a shift away from purely military work as several companies approached the RAE for assistance with the design and handling characteristics of their new civil aircraft. The first Certificate of Airworthiness was also issue to a civilian aircraft at this time. As well as this 1919 also saw the beginning of the early helicopter work undertaken by Louis Brennan. Based in one of the airship sheds on the site he continued testing until 1925 when it crashed during a demonstration and the Air Ministry cut the project’s funding.

In 1920 the Wireless and Photography department was formed, illustrating the growing importance of these technologies, and more sophisticated equipment was installed in the structures department to test wing loading, replacing the previous method of using sandbags to weight aircraft components.

The research activities of the RAE continued throughout the 1920s. These included comparisons between the results gains from full scale flight tests and those from models tested in wind tunnels as well as theoretical studies of stability and other flight characteristics. Other work included the development of an early variable pitch propeller and the testing of many of the new types of aircraft that were being developed by numerous companies. The development of oxygen systems for aircrews was also undertaken due to the increased altitudes that were being encountered both in tests and in everyday flight.

Also, during the 1920s a great deal of research was undertaken in the development of aircraft catapults. These used a compressed air and hydraulics to launch aircraft and would be later developed for use on the Royal Navy’s large warships. Further work would be undertaken on inflight refuelling and 1927 would see the start of experiments to develop turbine engines by Alan Arnold Griffith. There was also a great deal of work undertaken on the RAE Larynx, an pilotless aircraft designed as a guided anti-ship weapons and seen as a predecessor to both cruise missiles and modern drone aircraft. Seven of these were produced and tested and, although it did not enter production, it was the start of the development of numerous drone aircraft that were used for gunnery targets, such as the Queen Bee that was used by the Royal Navy during the 1930s.

The development of photographic equipment was an important area of development in the interwar period and in 1929 the RAE produced the first of its F24 aircraft cameras. This was fitted to many aircraft during the Second World War for aerial reconnaissance and would continue to be used until the mid-1950s. An Instrument and Photographic Department was also formed to help with the development of equipment for aerial photography, reflecting its growing importance both in military and civilian circles. The problem of spinning in aircraft was also tackled at this time with the production of a 12ft wind tunnel in which to conduct tests. This was followed in 1935 by a 24ft tunnel that was used to test air and water-cooled engines and other full size components. A 660ft tank was also built to test the hydrodynamics of seaplane hulls. Finally, in 1937 an additional wind tunnel was constructed that was able to operate at 600mph, reflecting the growing performance of aircraft at the time.

The declaration of war in August 1939 ““made little fundamental change in the policy and work of the Establishment since it was the expected culmination of what was known as the ‘Expansion Scheme’ which had been going on progressively since the adoption of a national rearmament policy in 1935”. Despite this there was a great deal of expansion with the number of staff increasing to 6,000 and new runways and hangars being constructed, which brought the airfield site up to 800 acres.

Despite the site’s importance, the RAE was only bombed once during the course of the war. This occurred on 16th August 1940 when eight aircraft dropped a total of 20 bombs, although only half hit the site with the rest falling on nearby houses. Three members of staff were killed, and work was disrupted for three days but would then resume, with some operations being dispersed to other sites.

During the war a large number of new systems were developed, including a gyro gun-sight that improved the accuracy of fighter aircraft and early forms of airborne RADAR, which were tested by the Radio Department. Tests on captured enemy aircraft were also undertaken as were early tests on models of the Gloster E28/39, Britain’s first jet aircraft. Advances were also made in aerial photography and a new bombsite was also developed as was a rocket propelled catapult designed to fire aircraft from merchant ships.

In August 1941 Beatrice Shilling, known as Tilly, developed the R.A.E. Restrictor, better known as Miss Shilling’s Orifice. This was developed to prevent loss of power in aircraft performing negative ‘g’ manoeuvres during combat and was a simple washer fitted to the fuel pipe that prevented the engine from being flooded by fuel. Although it did not completely solve the issue it did allow for quick low ‘g’ manoeuvres to be conducted and bought time for a more permanent solution to be developed by Rolls-Royce, in the form of pressure carburettors.

With the end of the Second World War in 1945 the RAE again underwent a reduction in staffing. From a wartime peak of around 6,000 this dropped to approximately 3,000 as many of the site’s personnel returned to the civilian industry. Also, in March of the same year research into piston powered aircraft ceased and all attention was focused on jet propulsion. In November 1945 the RAE was opened to the public in order to illustrate the site’s war work. Not only was the site opened but there was also a display of British and German aircraft which drew a great deal of attention.

In the immediate post war years research continued, although at a much reduced intensity, and included a great deal of research into transonic flight characteristics. Some of this was undertaken using rocket propelled models dropped from aircraft in flight. Some research was also conducted on the Miles M.52 prior to this project’s cancellation. A further area of investigation at this time was the installation of flexible decks on aircraft carriers. This hope to replace the undercarriage of aircraft with a sprung rubber deck on ships. It was hoped that this would increase the performance of aircraft, but it was never implemented in service. A more successful design was the angled flight deck, which was proposed by the Naval Aircraft Department and, after a model was produced and refinements implement, this was adopted as standard for all aircraft carriers at the time.

In 1948 the Society of British Aircraft Constructors moved their annual display to Farnborough. This would continue to be held annually on the site until 1962, when it changed to a biannual display in partnership with the Paris Air Show. Although initially this was only open to British designs from 1974 it became the Farnborough International Airshow. In 1952 the air show was the site of an major accident when a de Havilland DH110 broke up during a display and crashed into the crowd, killing 31.

During the 1950s a substantial amount of testing was undertaken on many new civilian designs if aircraft and, even though some of these did not enter service, a great deal of technical information was gained from the experiments. Helicopters also began to undergo testing at the RAE with numerous aspects of their design being tested. 1952 also saw the arrival of an Avro 707 which was used to examine the aerodynamic properties of delta wings, data that would be later used in the design of Concorde and the Avro Vulcan.

Following the loss of two Comet aircraft in 1954 the RAE was the site of a major investigation into the causes of their loss. Parts were salved from both of the crashes and brought back to Farnborough where they were pieced back together. Further to this a large water tank was built where a complete Comet body was repeatedly pressurised to investigate the effect of repeated pressurisation and depressurisation. Other Comets were also sent to the RAE to conduct flight trails and other investigations. All of these tests found that the aircraft had been lost due to the failure of the structure and led to a redesign of the type, as well as a greater understanding of the science of metal fatigue.

By 1958 the structure of the RAE had developed to have the following departments: Aerodynamics, Armament, Armament and Instrument Experimentation, Carrier Equipment, Chemistry, Electrical Engineering, Experimental Flying, Guided Weapons, Instruments, Instrument and Photographic, Mathematical Services, Mechanical Engineering, Metallurgy, Naval Aircraft, Radio, Rocket Propulsion and Structures.

1958 also saw the beginning of calculations on the TRIDAC analogue computer as well as the launch of many of the rocketry projects that the RAE was involved in. These were the Skylark and Black Knight rockets that were both tested at the Woomera facility in Australia.

During the 1960 the RAE was involved in a number of projects ranging from the development of the UK3 satellite, the first UK satellite, and the TSR2 aircraft to the invention of high strength carbon fibre. RAE scientists would also be present at the first launch of the Blue Streak rocket in 1964. This period also saw work undertaken as part of the development of Concorde, including testing the airframe for the effects of heat and stress.

In 1970 the Royal Aircraft Establishment was involved in the launch of the R1 satellite by the Black Arrow rocket from the Woomera test site. This was the responsibility of the space department and built on the work they had undertaken on the previous Black Knight system. They would also have design authority for the Prospero satellite that was launched in 1971 and the Ariel IV, launched in 1973.`` 1970 also saw the opening of the RAE Museum on the site. For the rest of the 1970s the RAE was involved in the development of satellite and senor systems, for both military and civilian uses. The increase in importance of the satellite research was demonstrated in 1988 when the RAE changed its name to the Royal Aerospace Establishment.

On 1st April 1991 the Royal Aerospace Establishment merged with the Admiralty Research Establishment, the Aeroplane and Armament Experimental Establishment, the Royal Armament Research and Development Establishment and the Royal Signals and Radar Establishment to form the Defence Research Agency. This brought together all of the previously independent Defence Research Establishments before it was itself merged with other departments to form the Defence Evaluation and Research Agency in 1995. Research flying would continue at Farnborough under these new institutions until 1994 when this end and in 2003 all Ministry of Defence operations on the airfield ceased.