It had always been intended that Blue Streak was to be launched from an underground site - what is now called a silo, altho the word wasn't in use in British circles at the time.
It also became very obvious that these silos were going to be horrendously expensive. Whilst the Treasury was prepared to allow some money for research, it was adamant that no work on silos was to begin in earnest.
Blue Streak silos would have been not only enormously expensive, but a considerable political hot potato. They would have to be sited on the eastern side of the country in gropund geologically suitable - and this meany prime Conservative constituencies. What the reaction would be is difficult to assess, but I doubt it would be favourable. They would also be a wonderful rallying point for CND.
The full blueprint for the silo is in the Public Record Office (DEFE 7/1392). It is extremely large and detailed, even to the location of the kitchen sink (look to the left of the missile). Its size can be gauged from the size of the missile - 10 foot across and 90 foot high. Also shown top left is a vehicle carrying a missile ready to be lowered into the silo.
Not visible in this drawing is a tube for the rocket exhaust. In addition, there is a half inch mild steel liner to the silo, which can be made out - this is to protect from the effects of electromagnetic pulse [EMP] which would otherwise burn out all the electrics in the silo.
In addition there was a 750 ton concrete lid, running on rails. High pressure hoses were to be provided to sweep it clear of debris before opening.
I suspect it was the thought of these silos, as much as anything, that led to the loss in favour of Blue Streak. Contrary to popular opinion, it was not a failure, but technically, highly succesful; not too expensive, as other systems were costed at equivalent sums; but possibly gave the impression of obsolescence. Its major problem certainly the use of liquid oxygen: altho de Havilland reckoned it could be topped in seconds rather than minutes, it could not be left fuelled for any length of time. And defuelling would take the missile out of service for some hours.
Cross section through the silo at third floor level
This needs to be related to the first plan, where the equipment room which here is lower right can be found on the third floor level. The missile is in the octagon upper right, seen from above, and again the scale can be gauged from the 10 foot diameter. The octagon is the launch tube, lined with acoustic tiles. The 5 lines converging onto the missile are light beams used to align the guidance system. Upper left is the efflux shaft: the exhaust gases from the missile vent up thru this shaft. Lower left in the launch console in the control room.
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