16/09/2026
Woodfords Supersonic Wind Tunnel
In the mid 1950s, with the Vulcan bomber in full production, designers at Avro were focusing on the next generation of high-speed bombers. A secret project was well underway to develop a new supersonic aircraft capable of flying at Mach 3. The futuristic Avro 730 was designed as a reconnaissance platform and strategic bomber, meeting the RAF’s continued requirement for an airborne nuclear deterrent.
The challenge was how to test the Avro 730 airframe designs – no wind tunnels anywhere in the country could create an airflow fast enough to simulate flight at Mach 3. So, 70 years ago in September 1956, development started on a new supersonic wind tunnel at Avro’s Woodford facility.
Traditional “constant flow” wind tunnels were unsuitable for creating such a high airflow, so the new supersonic wind tunnel utilised an “intermitted blowdown” design. Air was pumped into a 40 feet diameter sphere to a very high pressure, and then released in a single blast through an adjustable nozzle and over the airframe model under test.
This Whessoe pressure sphere, made from welded 1.25” steel plates, was pressurised by two Broom and Wade compressors which took 70 minutes to pump 7.75 tons of air into the sphere at 100lbs/sq in. This air needed to be both cooled and dried.
With the model under test installed in the small, 30” x 27” chamber, the air in the sphere was released via a hydraulicly operated valve, which fully opened to a diameter of 36” over 2 seconds. The valve would adjust automatically to compensate for the reducing pressure in the sphere to achieve a constant airflow for around 40 seconds, up to Mach 3.5.
The models needed to be constructed from high strength steel to withstand the massive loads resulting from the air blast, and heat exchangers were employed to deal with the temperature drop caused by the rapidly expanding air.
The building structure of the supersonic wind tunnel remained at the Woodford site until quite recently, but has now been demolished to make way for housing. And the Avro 730 project? Cancelled in 1957…but more on that in a future post and an upcoming exhibition at the Museum.
Interested to find out more about the fascinating history of innovation at Avro Woodford? Come along to the Avro Heritage Museum and see for yourself! https://www.avroheritagemuseum.co.uk