You Spin Me Right Round, Baby…
At the September meeting Twyford and District 41 Club visited the historic Man-Carrying Centrifuge at Farnborough. Built in the early 1950’s, and opened in 1955, the centrifuge is the only example of a centrifuge designed and manufactured by British engineers, and is believed to be the oldest example in the world.
The effects of high G forces on pilots had been experienced by the end of World War 1 and during the Schneider Trophy Races of the 1920’s. But little research was carried out in the UK to understand the effects of G Force and develop protection for pilots.
As the country prepared for the second World War it was decided that G Force protection was urgently needed for aircrew. Early studies were conducted in service aircraft. But this was problematic as it was difficult, if not impossible, to replicate the required G Force profiles in a controlled and safe way.
So it was decided that the UK should build its own centrifuge - a machine capable of replicating the high G environment in a controlled, repeatable and safe way. Work started in 1951 and completed in 1955. The centrifuge was in constant use until 2019 - when it had completed 122,133 test runs. During 64 years of operation the centrifuge has had only one known failure when a feedback circuit failed leading to system going up to 15 G’s. Fortunately no one was injured, but did result in some colourful language from the test pilot!
Our visit started with an informative presentation on the history of the centrifuge and an explanation of the effects of high G Forces.
Aircrews experience significant increases in G Forces while flying modern fighter jets. We all experience the effects of gravity; standing is referred as 1G. But at times the body can experience increased G Force - think of your last roller coaster ride where the twists and turns can increase G Force up to 4G (i.e. 4 times normal 1G).
But aircrews, flying aerobatics or engaging in air combat will experience increased levels of G Force - with modern, fast aircraft capable of pulling up to 9G - meaning the pilot weighs 9 times more than normal.
The human body has evolved to operate at 1G, subjecting the body to higher levels of G Force can result in problems. One of the more serious effects is what happens to the cardiovascular system, particularly blood pressure in the eyes and brain. This can lead to temporary blindness and loosing consciousness - G-LOC (G-Induced Loss of Consciousness).
The work of the team in Farnborough has lead to a number of solutions to prevent, or reduce, G-LOC. These include anti-G Trousers, air-filled trousers that apply pressure to the legs to stop the blood draining from the head, and Pressure Breathing for G-Protection (PBG) where breathing gas is forced into the lungs in proportion to the G being pulled.
The research in Farnborough, and resulting developments, are now being used around the world to protect aircrews from the effects of high G Forces.
The centrifuge chamber is 80 feet (24.4m) in diameter and the walls are 2 foot thick. The central centrifuge measures 60 feet (18.3m) between the gondola pivots. At the end of each arm is a gondola (or car) weighing in at 1,150 Ibs (or 523 kg) and these can be accelerated, at 1G/sec, up to 30G (115mph at 54 rpm). But the system is restricted to a maximum of 9G for testing (63mph / 30rpm).
After the meeting we moved to a local pub for the usual meal and refreshments. All agreed that it was an excellent evening and we were impressed by the work of the Farnborough research team, but more importantly, the results of the research carried out and how it had huge impact on improving the safety of aircrews around the world. Made us all proud to be British.
