On Thursday 8th May, we had the pleasure of welcoming some members of Cranfield University, past and present, to BBMF for a special tour.
University Archivist Karyn, and Lecturers Andy and Jelle, were invited to visit BBMF as a thank you for the work they have done, and continue to do, helping put together information for the upcoming 80th celebrations of our Lancaster, PA474. Their passionate research, uncovering the history of the aircraft, has helped not only with the anniversary but also with the Flight’s understanding more about the trials she underwent when part of the College of Aeronautics fleet between 1954 and 1964, and also helped us understand where some of PA474s unique modifications originated from.
Also joining the team was an old friend from PA’s past. Mr David Hyde joined the College as research assistant and a Flight Test Observer, managing the flight test programme for the Laminar Flow trails PA conducted in 1959, and hasn’t seen her in-person in over 60 years. As Flight Test Observer, David and his teams research helped reshape aviation design by developing a greater understanding of the importance of airflow over aerofoils. The research was carried out for Handley Page, who wanted to test methods of Boundary Layer Control on a swept-back wing configuration, and so three different types of wing design were used: A Constant Chord wing, a half-scale Folland Midge tapered swept-wing, and a half-scale Midge wing with an experimental suction system. David’s focus in 1959 was on the first Folland Midge wing, studying the static pressure distribution across the wing, over an incidence range of 0 to 10 degrees which was achieved via an electrical actuator operated by the pilot. The result of these tests found that the “Chordwise pressure distribution compared well with theory and the loadings were in close agreements with initial predictions”, and in March 1960, David published his first paper.
Upon a brief hiatus away from Cranfield, on expedition across Africa and the Americas with his fellow Imperial College post-graduates, David returned to Cranfield and continued his work with PA474. This time the modified Midge wing with the suction elements was in use. The aim of this stage of research was to discover ways to “raise the Reynolds Number for full chord laminar flow, which was initially prevented by turbulent disturbances at the root, contaminating the wing surface”, put simply, a way to control the instability within the boundary layer. A boundary layer is formed as air flows over the wing, where a thin layer of slower-moving air forms next to the surface. At certain positions over an aerofoil, this layer from a streamlined, laminar flow and becomes turbulent, causing drag and reducing lift. Not ideal for the new aircraft of the Jet Era. ‘Boundary Layer Suction’ includes small slots across the surface of a wing, normally utilising an air pump of some kind (In PA474s case, two Budworth turbine engines mounted rear of the bomb bay), to gently suck some of the slow-moving air from the boundary layer, resulting in the smoother, faster airflow known as ‘Laminar Flow’. Despite initial issues with the test equipment, and before PA474’s time at Cranfield came to an end, the testing appeared successful with the suction system providing “Adequate control of the boundary layer”. PA474 then left Cranfield in 1964, being replaced with an Avro Lincoln to continue the research.
During the visit, David and the group were shown items in BBMF’s possession relating to PA474s test-bed years by AS1(T) Mantras-Barratt, who has been involved with planning the Lancasters 80th Birthday celebrations, along with how the items provided by Cranfield will be used in the celebrations. The group were then taken on a tour of our hangar guided by Mr Carl Proctor, who has also used the items provided by Cranfield to create a 1:48th scale model of the Folland Midge wing, with the day ending in David’s long-awaited reunion with PA474 and meeting some of the crew who fly her today.
We thank David and the Cranfield team, past and present, for all they have done keeping PA474 airworthy, and their work in helping ensure her legacy lives on.
You can read David’s 1960 paper here: https://dspace.lib.cranfield.ac.uk/items/05177e67-6b9a-4211-ad51-c5f3bd6a6b38
Image Credits: RAF Coningsby Photography Section, Cranfield Archives, Jelle Hieminga.
