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Dealing with some of the technical problems and a financial crisis

RELATED STORIES

Troubles building the MK I Radio Telescope (Part 2)
Bernard Lovell Astronomer
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I will deal with the strengthening of the bowl, to begin with, which was a major factor. I had asked for really the whole bowl to be made of small mesh to increase the efficiency of the telescope on a very much higher frequency of which it had ever been originally designed. Now, the trouble was that the use of such a small mesh, you had to then to assume that the bowl would become completely opaque to any storms, and this led to a profound change in the design of the whole structure, which was to be elevating. Instead of building the bowl on a cantilever stretching between the two trunnions on the top of the 180 foot towers, we had to reside, in putting on this extra loading, there was no further point in strengthening the cantilever, because it was itself then not strong enough to bear what we were asking. In other words we were in a fix. So Husband’s answer was the one that now exists, that was for us to redo, to do away with the cantilever and build the cylindrical structure, which is now the foundation of the telescope, and exists. And thank heavens this happened otherwise the telescope would have been no good by this time. Now, the other thing- That of course led to considerable increase in cost, but I was not particularly worried about that, because I had assured both the Vice Chancellor and Husband that the Air Ministry would meet this extra cost. Now, two other things happened in that year. First of all, we had obtained from Metropolitan-Vickers an estimate of I think about £30,000 or £40,000 for the manufacture of the bogies, and for the manufacture of the electrical system, which was going to be a metadye system, to drive the telescope, and when Husband asked them for an estimate, in 1955, to our amazement, the cost, which they had previously given of £40,000, turned out to be at least double. That was not the end of our troubles. I had given a lecture at a National Physical Laboratory, and after the lecture, this man called Saxton, who was the Aerodynamics expert came to me, and said- Lovell, have you, he said- you’ve tested your design in the wind tunnel, have you? And I said- oh yes, it’s perfectly all right. We have the, the structure will be safe to wind speeds of 80 miles per hour, which, according to the Meteorological Records is the highest which can ever be contemplated on a Cheshire Plain. He said- yes, but he said- have you heard about the disaster, which has afflicted the Tacoma Bridge, over Washington State? So I had heard nothing about this disaster. Now, the Tacoma Bridge across the Washin- across Washington State had been built to withstand quite high winds, but it had recently been completely destroyed in quite low wind speeds, with, of a certain frequency. In other words, it’s all right for a steady wind, of, that bridge was all right for a steady wind of maybe 80 or 100 mph, but with wind speeds as low as 30 or 40, with certain types of gusts, it was wrecked. And Saxton produced a film of this happening, and it was horrible to see the build, bridge suddenly twisting and then fracturing in the middle. So I reported this to Husband, and he was severely displeased, because, you know, he severely, like I, and like many other people, had not yet heard of this disaster, so he said, well, there is only one thing we must do. We must build a small scale model, a tenth scale model of the telescope, and we will simulate the driving racks and trunnions with springs, and we will take them to the wind tunnel at MPL, the low speed wind tunnel, and see what happens. So we did this. And the result was alarming. At high, steady wind speeds, the structure was perfectly stable. The steady wind speed was then reduced, and gusts, simulated gusts were put in. Oh! With low wind speeds of 30 or 40 mph, and with certain types of gusts, which are normally associated with those wind speeds, the whole structure of the connection of the bowl to the trunnion bearings was shattered. You know, this was a most alarming situation. So in other words, these gusts were making the bowl oscillate and thereby wrecking, in those cases, the springs, but they would certainly have wrecked, in practice, the great gun racks on which we were proposing to move the telescope. So those were three major troubles that beset us in 1955.

Bernard Lovell (1913-2012), British radio astronomer and founder of the Jodrell Bank Observatory, received an OBE in 1946 for his work on radar, and was knighted in 1961 for his contribution to the development of radio astronomy. He obtained a PhD in 1936 at the University of Bristol. His steerable radio telescope, which tracked Sputnik across the sky, is now named the Lovell telescope.

Listeners: Alastair Gunn Megan Argo

Alastair Gunn is an astrophysicist at Jodrell Bank Observatory, University of Manchester. He is responsible for the coordination and execution of international radio astronomical observations at the institute and his professional research concerns the extended atmospheres of highly active binary stars. Alastair has a deep interest and knowledge of the history of radio astronomy in general and of Jodrell Bank in particular. He has written extensively about Jodrell Bank's history.

Megan Argo is an astronomer at the University of Manchester's Jodrell Bank Observatory researching supernovae and star formation in nearby starburst galaxies. As well as research, she is involved with events in the Observatory's Visitor Centre explaining both astronomy and the history of the Observatory to the public.

Tags: Tacoma Bridge, Washington, Charles Husband

Duration: 7 minutes, 1 second

Date story recorded: January 2007

Date story went live: 05 September 2008