Category A VERTICAL EMPIRE

The Air Ministry, set up in 1919 to oversee the RAF, was represented in Cabinet by the Secretary of State for Air. Although both Winston Churchill and Harold Macmillan had held the post, during the 1950s and 1960s the position was occupied by ministers who were not destined for greater things, the office holders being respectively Lord De L’Isle and Dudley, Nigel Birch, George Ward, Julian Amery and Hugh Fraser. The post was abolished in 1964 when the Air Ministry was absorbed into the Ministry of Defence.

There was controversy over the procurement process for what would today be called weapons systems, such as Blue Streak. When the Air Staff had decided on the specification for a new project, they would issue an Operational Requirement (OR). The project would often have come through the DRPC – Blue Streak is a good example. In 1953, the DRPC had been studying missile development and had decided that both a ballistic missile and a defence against a ballistic missile should be investigated. This led to the issuing of the OR for Blue Streak in 1955 (and also one for an anti-ballistic missile defence, but this did not get very far).

The Air Staff might have issued the OR, but it was up to the Ministry of Supply to circulate the requirement to industry, take in the proposals, evaluate them and issue the contract to a particular firm. It would then follow the project through to service entry.

In principle, solid fuel motors are very simple. A tube is filled with the fuel/oxidant mixture, which is then ignited – but as always, there is rather more to it than that. Early motors used simple cordite, a mixture of nitroglycerine and gun cotton, and were end burning – that is, the cordite at the end of the tube is ignited, and the cordite burns upwards towards the other end. Cordite was

replaced by propellants based on ammonium perchlorate (NH4ClO4) and ammonium picrate (C6H2(NO2)3O. NH4) with small amounts of other material added.

A British innovation was that of centre burning. An empty cylinder runs the length of the tube. The igniter is at the top, and when initiated, the fuel burns from the centre out to the edges. One obvious problem is that the surface area increases as the burning spreads out, and one way to overcome this is to have a star-shaped cut out (see Figure 21).

From the military point of view, solid fuel missiles are vastly preferable to liquid fuelled ones. The solid fuel tube has to be very strong to withstand the high pressures and temperatures inside, thus making it
very robust when it comes to handling. Liquid fuelled missiles, however, have very thin tank walls, and in any accident there is the potential to spill a good deal of rather nasty liquid. With solid fuel motors, it is a question of point and fire; liquid fuelled missiles need a good deal of careful setting up.

Solid fuel motors have other advantages: by varying the geometry or the combustion mixture, motors can be made that give very large thrusts for very short periods of time, or smaller thrusts for a longer period. The Gosling boosters for the Bloodhound missile accelerated the vehicle to over Mach 2 in three seconds. The thrust is not uniform, as the graph below shows11. In particular, there tends to be a long tail off as the last slivers burn away (see Figure 23). For these reasons, the thrust and burning time given in reports are only approximations.

Solid fuel motors have two disadvantages in a satellite launcher: they tend not be very energetic (have a low S. I.) and have a poor mass ratio (mass full/mass empty). S. I. is related to the exhaust velocity of the gas (in modern units, they are the same), and final velocity of a rocket stage is given by:

Vf = Ve x ln(mass ratio)

Thus the first Black Knight rocket, BK01, had an all up weight at launch of 13,072 lb, and 1,424 lb when empty. Hence its mass ratio was (13,072lb/1,424lb) = 9.18. With an S. I. of around 220, its final velocity in the absence of any other forces would be (220 x 9.8) x ln(9.18) = 4,800 m/s. Performing the same calculation on the Cuckoo II motor, used as the second stage on later Black Knight vehicles, gives 3,750 m/s – quite a significant difference.

There are two obvious ways of improving performance: increasing the S. I. of the fuel, and making the case lighter. Hence later solid fuel motors became more efficient. The solid fuel boosters either side of the Shuttle have an S. I. of 242 at sea level (268 in vacuum). There is also another way to improve performance, which is simply to build them bigger. The mass ratio improves with size since the amount of material for the case is proportional to the radius of the tube, whereas the amount of fuel inside is proportional to the square of the radius.

Most British solid fuel motors were relatively small. The largest was the Stonechat, with a diameter of 36 inches. The Stonechat formed the basis of the Falstaff vehicle, which was used to test components of the Chevaline system. (Chevaline was a Polaris upgrade programme whereby one of the three re-entry vehicles and its warhead was removed to make way for an elaborate system of decoys.) Even so, its total impulse was only 1,700,000 lb. s as against Black Knight’s 2,300,000 lb. s.

It is interesting to compare Stonechat to the Algol 1 motor (first flown in 1960), which was used as the first stage of the original Polaris missile and also as the first stage of the Scout satellite launcher.

In terms of S. I., the two look equivalent, and the mass ratios compare quite favourably, being (23,600/4,100) = 5.8 for Algol and (10,300/1,800) = 5.7 for Stonechat. The later A3 Polaris missile had a first stage with a much better mass ratio: (24,400/2,790) = 8.7. The weight saving was achieved by using a fibreglass casing.

Several 17-inch motors derived from a motor called Smoky Joe, so named from the plume it produced when burning. These include the Albatross, Cuckoo, Goldfinch, Raven and Rook. The Raven and Rook motors were employed in a variety of different roles in the 1950s and 1960s.

The motor tube of the Rook and the Raven consisted of two wrapped and welded cylinders 90 inches long which were butt welded together. The tube was made of steel of thickness 12 SWG (0.104 inches or 2.64 mm). Head ends were welded to the tube: the top end had a threaded opening for allowing the charge former to be centralised during propellant pressing and allowing excess propellant to ‘bleed’ off. Later, the igniter would be fitted in the opening.

These two motors formed the backbone of the various solid fuel vehicles used for a variety of research purposes, with several hundred motors being fired. The Raven formed the basis of the Skylark vehicle.

Below is a table listing a few of the motors developed at RPE. This is taken from a manual of solid fuel motors which listed data for a total of 73 different types of motor12.

These data are taken from an index of solid fuel motors developed at RPE Westcott in the mid-1960s. The table shows only a small selection – 73 motors were listed in all. These rockets were used for a variety of different purposes:

Extra boost for first stage of Skylark.

Black Knight re-entry tests.

Skylark.

Black Arrow – stage separation and to settle propellants in tanks. Red Shoes, which became the Thunderbird SAM.

Falstaff vehicle for testing of Chevaline components.

Third stage of Black Arrow.

The most famous solid fuel rocket produced in Britain was Skylark, which had a remarkably successful career. First launched in 1957, from Woomera, its final launch took place from Esrange, Sweden, on 2 May 2005. In all, there have been 441 launches, from sites in Europe, Australia, and South America.

The design first dates to 1955, when initial work was carried out by the RAE and the RPE. The first vehicles were ready less than two years later, and sent for testing to Woomera during the International Geophysical Year.

During the 1960s Skylark evolved into an excellent platform for space astronomy, with its ability to point at the Sun, Moon, or a star. It was used to obtain the first good quality X-ray images of the solar corona. Within the UK national programme, the frequency of Skylark launches peaked at 20 in 1965 (from Woomera), with 198 flights between 1957 and 1978.

Skylark began as a simple one stage vehicle, with three fins and a relatively long burn time of 30 seconds, using the Raven motor. This was to keep the accelerations within reasonable values. A series of different Raven motors were produced, each with a different filling as requirements changed. As a consequence of the low acceleration, a tower was needed to guide the rocket for the first few seconds. This was simple in construction and used components from Bailey bridges!

An extra boost stage was added to improve performance. Initially, this was the Cuckoo motor (so named, apparently, because its function was to kick the Raven out of its nest). Later versions used the Goldfinch motor in place of the Cuckoo.

The following description of how Skylark was used by the space science community was written by Professor Mike Cruise13, who has had a long and distinguished career in space science.

Many of the senior space scientists around the world were trained in space instrument design, data analysis and space project management on projects using the Skylark sounding rocket as the space platform. In the nineteen sixties and seventies over two hundred Skylarks were launched from sites in Norway, Sardinia, Australia and South America offering five minutes of observing time above 100 km and substantial payload carrying capacity. Many of the Skylark flights delivered data which ended up in Doctoral Theses, launching the careers of the students involved. A PhD gained by this route involved science, engineering, travel and exposure to many different professional cultures…

The scientific instrument was constructed on a circular bulkhead of magnesium alloy which was previously delivered from BAE as part of the Skylark ‘Meccano kit’ … The design of the Skylark provided great flexibility for the experimenter. Holes could be cut in the cylindrical bays or in the circular bulkheads provided the design was approved by BAE at Filton. The strength of the vehicle was in the magnesium alloy cylindrical skin. Generally four or five cylindrical bays would be mounted on top of one another containing the parachute, batteries, the control and telemetry systems and then the attitude control system if one were employed. Usually the experiment bay was mounted at the top under a conical nose cone which split longitudinally in two sections after reaching altitude.

A few hours prior to launch, the stack of Skylark bays with the nosecone at the top and the parachute bay at the bottom was mounted on a small trolley and taken by road to the Skylark launcher. The vehicle was rail launched – that is, there were three parallel rails mounted vertically in the launch tower and metal shoes were fitted at various positions along the length of the vehicle to engage with these rails. The fins extended outside of the rails, in the azimuthal spaces between them… The launcher tower was about 50 metres tall and the whole launching assembly could be tilted to angles of about 15 degrees from the vertical to adjust the trajectory for winds.

It was necessary to make calculations of the ballistic winds at various heights to predict the trajectory as the vehicle was only powered for 35 seconds of the ascent phase and had no guidance system.

Balloons were launched and tracked by radar for several hours beforehand to provide this data on the winds up to 10 or 15 kilometres altitude. In addition, there were various instrumentation checks and the firing of sighter rockets to check that all the radars and kine-theodolites were functioning correctly before a firing took place.

Figure 26. A Skylark launch from Woomera.

Normally the experimenters watched the launch proceedings from the block house, EC2, a concrete building below ground level, built into the edge of the concrete launch apron. All the control connections to the vehicle came to EC2 and there were telemetry receivers to check data from the instrumentation and the experiment. In a separate room in EC2, an Australian military technician did the actual firing by starting an automatic sequencer two minutes before launch. This counted down and issued the firing pulse to
the detonator in the booster motor at the pre-programmed time. Up to two seconds before launch the launch could be stopped using a line attached via a small snatch connector to the side of the instrumentation bay. Several people in EC2 had ‘Stop Action’ buttons which could abort the launch via this route. The snatch connector was left in place as the launch proceeded and the wires literally snatched from the side of the vehicle as it departed.

What did the Skylark programme produce in the way of benefits to the UK and the students concerned? Some very new science in most cases. Studies of the ionosphere, the middle atmosphere, X-ray sources, UV spectra of stars and, towards the end of the programme, some Earth observation data – all were progressed by Skylark experiments and contributed to the early development of space science. The Skylark engineering design was conservative to say the least, and most of the experiments were far in advance of the instrumentation that supported them. Mechanical switches were still being used to multiplex the telemetry while semiconductor storage was being employed to capture science data in the experiment. This conservatism was a lost opportunity for UK space companies who, given a freer hand, might have built more advanced equipment with consequent spin-off for the emerging satellite telecommunications industry. Undoubtedly the restraining hand of RAE Farnborough was at work in this respect.

The parachute failures dented the effectiveness of the whole programme and were a factor in letting the US pull ahead in many scientific fields. As the payloads became heavier and longer, the parachute design remained the same and success rates suffered. It must be recorded that, by the middle of the seventies, sounding rockets were losing their place to satellite borne equipment. Why spend three years building rocket borne equipment to gather five minutes of data when you could spend five years building satellite borne equipment that would deliver three years of data? The economics were against investing in new rocket technologies. The range at Woomera was extremely effective in the late sixties and the BAE team did their very best within the hardware limitations to ensure the experimenters gained the data they wanted.

The big contribution of the programme was the opportunity for young scientists and engineers to experience a space project from beginning to end within a PhD duration of three or so years. Vicarious benefits included seeing a snapshot of the whole British colonial experience in the space of a few days journey across the world and the opportunity to test oneself in management terms against time, technology and resource constraints. The nostalgia felt by those who experience a Skylark PhD is fuelled by the current lack of any replacement for the horribly realistic management training it provided.14

UCL in 1979 and became Deputy Director of MSSL in 1985. In 1986 he moved to the Rutherford Appleton Laboratory and became the Associate Director for Space Science in 1993. Moving to the University of Birmingham in 1995, he was appointed Professor of Astrophysics and Space Research and in 1997 became Head of the School of Physics and Astronomy and subsequently Pro Vice Chancellor for Research and Knowledge Transfer. 14 This section was published in an expanded version in issue 5 of the journal Prospero, published by the British Oral History Project.

1. The Government have been considering the future of the project of developing the long-range ballistic missile Blue Streak, and have been in touch with the Australian Government about it, in view of their interest in the joint project, and the operation of the Woomera range.

2. The technique of controlling ballistic missiles has rapidly advanced. The vulnerability of missiles launched from static sites, and the practicability of launching missiles of considerable range from mobile platforms, has now been established. In light of our military advice to this effect, and of the importance of reinforcing the effectiveness of the deterrent, we have concluded and the Australian

Government have fully accepted that we ought not to continue to develop, as a military weapon, a missile that can be leached only from a fixed site.

3. To-day our strategic nuclear force is an effective and significant contribution to the deterrent power of the free world. The Government do not intend to give up this independent contribution, and therefore some other vehicle in due course will be needed in place of Blue Streak to carry British-manufactured nuclear warheads. The need for this is not immediately urgent, since the effectiveness of the V-bomber force as the vehicle for these warheads will remain unimpaired for several years to come, nor is it possible at the moment to say with certainty which of several possibilities or combinations of them would technically be the most suitable. On present information, there appears much to be said for prolonging the effectiveness of the V-bombers by buying supplies of the airborne ballistic missile Skybolt which is being developed in the United States. H. M. Government understands that the United States Government will be favourably disposed to the purchase by the United Kingdom at the appropriate time of supplies of this vehicle.

4. The Government will now consider with the firms and other interests concerned, as a matter of urgency, whether the Blue Streak programme could be adapted for the development of a launcher for space satellites. A further statement will be made to the House as soon as possible.

5. This decision, of course, does not mean that the work at Woomera will be ended. On the contrary, there are many other projects for which the range is needed. We therefore expect that for some years to come, at least, there will be a substantial programme of work for that range.23

The Opposition based their first attack on the grounds of waste of large sums of public money, which Watkinson was able to counter with the argument that Blue Streak would be developed as a satellite launcher. It was a useful point for the Opposition to seize on, as it was an issue which could cover its own internal divisions about the deterrent.

But the satellite launcher option was a useful defence, indeed the only defence open to him, which raises the question: how genuine a statement was this? Did Watkinson and the Ministry of Defence really want a satellite launcher, or was this statement merely a political fig leaf? Given the enthusiasm (or lack thereof) with which the subsequent Cabinet committee greeted the topic, the suspicion is that the fig leaf is the correct answer. Certainly the initial reaction among those in the House was quite vigorous: George Brown was the then Shadow Defence Secretary, and demanded an immediate emergency debate, which, however, was not forthcoming. (Sandys’ absence from the House was noted by Jim Callaghan, who seized upon it to say: ‘I was commenting that it was a little unfair that the Minister of Defence should have to face all this music, and I was wondering where the Minister of Aviation is and when he is going to resign.’)

Given the costs of the project at the time of cancellation, the Opposition managed to force a later debate. Whilst Brown might have been a good speaker, what he said at the debate does not read well today. This is partly because, like all Opposition speakers in any debate, he had not had the Civil Service back up and briefings that Ministers have. It is also interesting to note that he seems to have had some inside information on ‘fixed sites’, but although he makes a great show of saying that he himself had advocated dropping the system, he sidesteps making any justification.

Although Watkinson, as Minister of Defence, opened the debate, Sandys was obviously the target for the Opposition. He gave a very straightforward speech in reply, even if he might not have been entirely convinced by his own side’s case. He was able to undercut Brown by resurrecting a quote from the time of Thor, when Brown had said that what the UK needed was its own missile with its own warhead, which is what Blue Streak had been. The other notable part about his speech is that, by Commons standards, it was not particularly partisan: he laid down the facts as he saw them, and did not attempt to make political capital from the decision.

But with the cancellation now official, interest within the Ministries of Defence and Aviation turned swiftly to Skybolt. The Navy was still not happy that Polaris had not triumphed, as can be seen from another internal Admiralty memo. It comments of Watkinson:

Skybolt lay ready to his hand (he thinks) as a blood transfusion to keep the V bombers effective from 1965-1970. … Our trouble is that the Minister has been advised by interested parties, in very optimistic terms, about Skybolt’s state and prospects. I would almost say that he has been led up the garden path. I would warn you that some of the advisers he will bring to you with him are bitterly anti-Navy.

It is ironic that 20 months later, in December 1962, Skybolt itself was cancelled by the US (as predicted by Brundrett and CGWL), and the UK had to negotiate hard to obtain Polaris. This meant that the ‘deterrent gap’ was now stretched to the late 1960s, and while the Polaris submarines were being built, the deterrent was being carried by V bombers with free fall bombs and the short range Blue Steel stand-off missile.

From the outset, the British Government had been warned that Skybolt was very much in the development stage, and there was no guarantee that it would actually be deployed by the USAF. The veteran Labour MP, Sydney Silverman, referred to Skybolt in the House of Commons in June 1960 thus:

Would it be a fair summary of what the right hon. Gentleman has told the House to

say that the result of his negotiations in the United States is that what he has really

done is to buy a pig in a poke with a blank cheque?

Whilst Silverman was making his attack mainly on party political grounds, there was more than a grain of truth in his comment.

Polaris did serve the UK well for nearly 30 years (although its mid-life upgrade, Chevaline, was also a source of controversy), and carrying the deterrent offshore leads to the argument that the mainland itself is no longer a target. Given however the number of NATO and US nuclear bases in the UK, that argument rather falls down. The cancellation of Blue Streak, and the reason given, meant that land-based missiles were never again an option for the UK deterrent. As to what purpose the UK deterrent was to serve, however, is another question.

The Powell report may have been ingenuous in its conclusions, but in the end, Blue Streak was indeed cancelled as a military weapon. Was this the right decision?

The answer to this can only be ‘yes’. Skybolt, had it been deployed, would have been almost as effective a deterrent for a good deal less money. Deterrents are there for political reasons: the whole point of them is that they should never be used! Britain’s deterrent was a perfect example – there was no way that it would be used without America becoming involved, and indeed that was one of the points of it.

As to the vulnerability issues, the RAF was considering a follow on to the Vulcan as a Skybolt carrier – in the form of the Vickers VC10 airliner.24 This is not as absurd as it sounds: airliners are designed to stay in the air for long periods and to have very short turn round times. The point of Skybolt was that the carrier aircraft would not need to fly anywhere near the enemy defences – and so an airliner would have been an ideal vehicle for the purpose. Proposals were put forward for a system of standing patrols (not possible with the V bombers) using 42 modified VC10s.

As it turned out, Skybolt was cancelled and Britain was offered Polaris. The submarines were designed by the Admiralty, and the whole project was carried out exactly on schedule and within budget – an achievement that had eluded the Ministry of Supply for a decade (and is still eluding the Ministry of Defence today). Polaris served the country well in its function as a deterrent, staying in service until the mid-1990s.

Blue Streak, even in its silos, would have seemed outdated by around 1970, if not earlier. It would not have been difficult to have built and designed a substitute which was smaller and cheaper (warheads had become very much lighter in the interim), and which could also have been based in the same silos, but given the pace and cost of the project up to 1960, how much the silos would have cost, and when they would have been finished, is a very open question.

This may seem to be an extended exposition of the cancellation in what is, in the main, a book on the British rocketry programme, but it had a very considerable impact on the future of Blue Streak as a satellite launcher, and thus by extension, on any potential British space programme.

At the time of cancellation there was still a good deal of development work to be done on Blue Streak. If the missile had not been cancelled, then the cost of this would have fallen on the defence budget. Furthermore, there would have been a number of test and development launches needed at Woomera, and the facilities there would also have been charged to the defence budget. Building a launcher from a fully developed Blue Streak would have been relatively cheap. The upper stages would have been Black Knight derivatives, and the development of Black Knight itself had not cost a great deal. The major cost would have been in building the interface between Blue Streak and the upper stages (a further expense which would have been worthwhile would be the uprating of the RZ 2 motor from the 137,000 lb thrust for the missile to 150,000 lb – this would allow for heavier upper stages). Thus a quoted cost of £65 million for a Blue Streak satellite launcher in 1960 might have been reduced to a tenth of that by 1964, making such a launcher far more probable. What such a launcher might have been used for is the subject for later discussion!

Single stage. Launched 30 October at 1959. Apogee 455 miles.

BK06 was a repeat of BK05 with a similar head but using a tape recorder to record separation and re-entry data. Vehicle performance was good, a re-entry velocity of 11,220 ft/second being achieved at 200,000 ft. There was some thrust even after the eight seconds allowed between burn-out and head separation; this caused collision between main stage and head, initiated the ejection of the pyrotechnic flashes and deployed the parachute on the ascent instead of later, as intended, during descent. The tape recorder in the head was switched on correctly and covered the separation phase and later part of the re-entry. The tape cassette, with recordings intact, was recovered together with the eroded durestos nose cone.

The rocket itself had a relatively simple task to perform, which was to boost its payload as high as possible, from where the re-entry vehicles would fall with as great a velocity as possible. Some launches were completely successful in that the rocket and the experiments yielded all the data required. Sometimes the launches were successful, but the experiments failed, yielding little data. However, even when the vehicle’s performance was below optimum, the experiments could still yield good results.

Failures that would have jeopardised orbital attempts had less impact on re­entry studies. The very first flight of all, BK01, ended prematurely when the destruct system operated inadvertently. There were also problems with engine overheating leading to kerosene starvation and resultant ‘cold thrusting’, particularly in the second (BK03) and fourth flights (BK05), but again, these were solved relatively early in the programme. ‘Cold thrusting’ occurs when the engine consumes HTP in the absence of kerosene: decomposition still takes place, but the thrust is very sharply reduced. In addition, on many flights the kerosene was exhausted before the HTP, resulting in a few seconds of cold thrust after ‘all burnt’. The discrepancy between the calibration during test firing and the actual launch was never pinned down.

The first stage of the vehicle performed exactly as intended on 15 of the 22 Black Knight flights. Other launches had problems in one way or another:

BK01: the self-destruct mechanism was accidentally triggered near the end of the flight.

BK03 and BK05: overheating in the engine bay lead to a fuel lock in the kerosene pipes, resulting in a long period of cold thrusting.

BK07: one chamber reverted to cold thrust after 100 seconds. Over 80% nominal velocity achieved.

BK14: pipe failure caused loss of kerosene: cold thrusting after 130 seconds. 85% nominal velocity achieved.

BK12: 6.8% difference in mixture ratio between flight and calibration.

BK23: premature shut down of engine due to gearbox failure 3 seconds before expected flame out.

Of the 22 flights listed, seven would not have made it into orbit if they had been satellite launch vehicles. Most of these problems could be considered as developmental difficulties that occur with any new technology. As a very first attempt at a modern liquid fuel ballistic vehicle, this is a fairly good record, with no major failures at all. It is also a tribute to the engineers at Saunders Roe and at Armstrong Siddeley Motors.

However, Black Knight was a success in a different direction. It gave RAE the confidence in the basic design, and as a consequence, many further projects were proposed using Black Knight as a basis. One, of course, was the Black Prince launcher and its various derivatives discussed in the BSSLV chapter. Another was Black Arrow – the subject of the next chapter.

The paper that follows is the Air Staff description of the prototype Blue Streak underground launcher. The prototype was known as K11.

A drawing showing a full reconstruction of the launcher can be found in Chapter 6 (Figure 50).

K.11 prototype underground emplacement

(1) The potential attacker is believed to have the capability to produce an explosion of 1 megaton yield on the ground or in the air with an accuracy of xh nautical mile from his target. The launcher must be able to withstand such an explosion and successfully fire its own missile without outside assistance within 24 hours.

(2) The emplacement must be able to fire the missile in all weathers.

(3) The emplacement must contain the missile and the necessary facilities for operating and servicing it and for messing and accommodating the concerned personnel. Since an alert may be sounded when the outgoing shift is handing over to the incoming shift, messing facilities must be adequate for two shifts.

(4) Storage space for the missile propellant fuels, food and other stores and equipment must be provided.

(5) Adequate ventilation including the efficient and speedy expulsion of missile exhaust after firing, must be provided together with facilities for conditioning, purifying and circulating air.

(6) Insulation against the electro-magnetic effects associated with a nuclear explosion.

(7) The emplacement must be self-contained for an emergency period of four days (covering three days before an attack is expected and one day afterwards).

II. SITE CRITERIA

1. Rock mass (hard chalk, limestone or better) not less than 300 ft thick and preferably with no overburden. But if overburden is present, it must be soft and not more than 25 ft thick.

2. Easy and firm access from main road to emplacement for transport of missile, equipment and stores.

3. Ease of guarding.

4. Neighbouring inhabited property must be more than 3,000 feet from the emplacement (this may be reduced as experience is gained in K.11).

III. DESIGN OF EMPLACEMENT

1. Basically, the emplacement consists of a hollow re-inforced concrete cylinder, 66 feet internal diameter, extending downwards from ground level to a depth of 134 feet and divided internally into two main sections by a vertical concrete wall. One section houses a U-shaped tube, the arms of which are separated by a concrete wall and are, respectively, the missile shaft and its efflux duct. The surface apertures of this U-tube are covered by a lid which can move horizontally on guide tracks. The other main section within the cylinder is divided into seven compartments, each with concrete floor and ceiling, for the various storage, operating, technical and domestic functions.

2. The internal diameter (66 feet) of the concrete cylinder is determined solely by what is to be accommodated. Protection against an explosion as… above is given by the lid and by the re-inforced concrete roof walls and foundations. The wall thickness will depend on the geological characteristics of the surrounding rock and may well be of the order of 6 feet. The depth of 134 feet is arrived at primarily to give sufficient clearance below the missile (itself 79 feet long) to allow for de-fuelling and re-fuelling the missile into and from the liquid oxygen and kerosene storage tanks located on the 7th floor.

3. A nuclear explosion produces certain electro-magnetic effects which could gravely injure the electronic systems built into the missile and on which its efficient functioning depends. To screen the emplacement from these effects the concrete cylinder will be wholly encased in W thick mild steel plate.

Missile shaft

4. The shaft is octagonal in section, 25 feet across and has an acoustic lining. The octagonal shape, which has been proved by tests, will facilitate the mounting of the acoustic lining and of the four hinged platforms which are spaced at intervals down the shaft.

5. The purpose of the acoustic lining is to prevent damage to the missile from the extremely high noise level produced by the main thrust chambers in the confines of the missile shaft.

6. The missile rests vertically in the shaft on a launcher supported by four suspension limbs attached to the wall of the shaft.

7. Access to the shaft for servicing purposes is through blast-proof doors opening on to the second and sixth floor.

Efflux duct

8. This has an area approximately 60% of that of the missile shaft and in section is half-octagonal in shape. This gives symmetry in the structure and at the surface aperture. A series of deflector plates at the exit will take the exhaust gases away from the missile as it leaves its own shaft.

Storage, Operating, Technical and Domestic Section.

9. This is divided into seven floors, as below, connected by a lift and staircase running from the first floor (at the top) down to the sixth floor:

First Floor

This floor contains:

(a) lid operating mechanism

(b) generating equipment

(c) air conditioning equipment

(d) blast valves for all intakes and exhaust ducts.

All this equipment has been centred as far as possible on this floor to avoid large air trunking systems being provided throughout the site. In the event of contaminated air being taken in, arrangements will be made to close off this floor (other than the general access facilities) thus allowing the generating and air conditioning plant to continue to operate without risk of contamination of the rest of the site.

Second Floor

This floor contains:

(a) Upper storage and maintenance area for the missile, together with two magazine type stores for the payload and the pyrotechnic equipment of the missile, i. e. retro rockets, head propulsion rockets, etc.

(b) Certain items of heating and ventilating equipment for which space is not available on the first floor.

(c) The refrigeration supply for the missile guidance equipment

(d) Blast proof access doors to the upper portion of the missile shaft.

Third Floor

This floor contains:

(a) Auto-collimator equipment

(b) Radio and communications equipment

(c) Site and missile control and checkout equipment

(d) Azimuth bearing and general purpose telescopes.

This floor level is controlled by the relationship required between the auto­collimator and the inertial guidance unit in the missile.

Fourth Floor

This floor contains all the general domestic accommodation including kitchen, recreation and sleeping facilities, etc., together with a small battery room and a switch room.

Fifth Floor

This is intended as the main storage area for the site generally. It also contains one or two tanks which it is not practical to put in the tank room on the seventh floor.

Sixth Floor

This floor is the lower maintenance area and contains the blast proof access door to the lower portion of the weapon shaft. Small hydraulic units are installed on this floor to supply the auto-pilot and launcher services. A small mono rail is provided that can be extended into the missile shaft for maintenance purposes. Access is also provided into the lox and kerosene [‘and water systems’ crossed out in original and ‘rooms on the seventh floor’ handwritten in]

Seventh Floor

This floor is divided in two by a structural wall to separate the liquid oxygen and nitrogen systems from the kerosene and water systems.

The Lox room contains:

(a) Main Lox storage tank

(b) Main liquid nitrogen tank

(c) High pressure gaseous nitrogen storage bottles

(d) The Lox start tank

(e) Liquid oxygen topping up pump

Subsidiary rooms contain:

(a) Liquid oxygen recondensing units

(b) Liquid nitrogen recondensing unit

(c) Liquid nitrogen topping up pump

(d) Liquid nitrogen evaporating plant

The kerosene room contains:

(a) The main kerosene storage tank

(b) The main water storage tank

(c) The kerosene recirculating pump

(d) The kerosene start tank

The access doors from the sixth floor will normally be kept closed and ventilation shafts are provided from these two rooms through the main structure to the surface pipe systems are also provided in these vent shafts for filling these systems from the surface,

IV. DESIGN OF LID

1. The detailed design of the lid is about to form the subject of a special design study by selected firms.

2. The purpose of the lid is to protect the missile from the effects of attack and to remain fully serviceable itself after such attack. Since the missile is completely unprotected when the lid is open, the time allowed immediately prior to firing the missile for opening the lid must be kept to a minimum and has been put at 17 seconds.

V. DESIGN OF SITE

1. The main requirement is to achieve maximum security and this calls for both the site and its immediate surrounds to be enclosed by a security fence and to be clear of obstructions to visions. The cleared area extends also beyond the site perimeter. The need to camouflage the site is at present being considered. A simple road system with associated hardstandings must be provided within the site.

2. The site will be about 3 acres in extent.

3. The site includes the main entrance to the emplacement, consisting of three flights of steps, protected only against weather and leading down to a cylindrical air lock giving access to the first floor of the emplacement.

The design and production of aircraft became the concern of the Ministry of Aircraft Production in May 1940. In April 1946 the Ministry of Aircraft Production was dissolved and its powers transferred to the Ministry of Supply, whose primary duty was the furnishing of supplies and the carrying out of research design and development for the services.

Firstly, this lead to problems in that the Ministry of Supply was responsible for developing aircraft, but at the same time, it would not be the end user, and thus lacked the incentive to overcome obstacles, and to speed the process along. Secondly, it did not have to operate the obsolescent material that the prototypes would replace, and so here too lacked that final sense of urgency. A third criticism was its industrial policy: projects were often not allocated to firms on the basis of their ability to carry them out, but often given to firms who were short of work in order to keep them busy. Sometimes the rationale behind some of the decisions was hard to fathom. Blue Steel was given to Avro, who had no experience whatsoever in guided weapons and had to set up a division from scratch – a process which must have cost a year or so of development time.

Reginald Maudling was Minister of Supply from 1955 to 1957. He has this to say about the Ministry in his autobiography:

When Anthony Eden became Prime Minister in 1955, he promoted me to Minister of Supply, which was my first full Ministerial post… It was a strange Department, and the target of a good deal of criticism, much of it justified. It was supposed to be concerned mainly with the supply of munitions to the three Services, and this was a large part of the routine work of the Department, but in addition it had responsibility for the aircraft production industry generally. The Government exercised a great deal of influence over the industry because, with the scale of modern projects and the vast amount of research expenditure involved, the industry had to rely heavily on the Government for contracts and for support. In addition, the Ministry of Supply was responsible for the Royal Aircraft Establishment at Farnborough, a quite remarkable institution, upon which industry relied heavily for scientific and technical support.

Inevitably we got caught in the middle in all disputes that went on between manufacturer and consumer. This was particularly true in the field of military aircraft, with the Air Force always demanding more from the manufacturers and complaining they were not getting their requirements met, while the manufacturers were saying that they were doing all that was possible and the RAF were asking too much. Relations between the Ministry of Supply and the Air Ministry were not ideal, and indeed I had from time to time considerable battles with Nigel Birch, who was then Secretary of State for Air. I came to the conclusion during the time I was there that the system was a bad one and that the interposition of a third party between customer and supplier, rather than acting as a pacifying agent, merely exacerbated argument. I did, in fact, recommend the abolition of the Ministry of Supply and when Harold Macmillan asked me to continue in that job when he became Prime Minister I naturally refused, because it seemed absurd to continue as Minister in charge of a Department whose existence I did not think was justified.1

Sir Frank Cooper, one of the senior Civil Servants of the time (among many other posts, Permanent Secretary at the Ministry of Defence from 1976 until 1982), had this to say about the Ministry of Supply in the context of the TSR 2, although his strictures could be applied more generally:

There was no doubt that relations with the Ministry of Aviation /Supply and the Air Ministry went from bad to worse and that these poor relations spread increasingly to the Ministry of Defence as a whole. The breach itself was of long-standing. The basic cause was lack of trust, particularly as regards the information received by the Air Ministry. The trust was lacking because the Procurement Ministry stood between the Air Ministry as the customer, and industry as the supplier. Moreover nothing seemed to arrive at the right time and at the right price, let alone with the desired performance. The lack of trust was exacerbated by the financial arrangements under which the Ministry of Supply/Aviation recovered production costs from the Air Ministry but was left with the research and development costs. Hence, there was no clear objective against which the supply department could assess performance and value.

An Overview

In 1945 the RAF and USAF had the world’s most powerful strategic bomber fleets, yet they were on the point of becoming obsolete, and the factor that was driving them obsolete was the jet fighter. The increase in performance that the jet engine gave to interceptors rendered the likes of the Lancaster and its derivatives hopelessly vulnerable. If airborne radar and guided weapons are added to the armoury of the fighter, the balance tilts even further away from the bomber.

One answer, of course, was to build jet powered bombers. The Air Ministry had been aware of this for some time, and before the Second World War had ended, had issued the Operational Requirements that would lead eventually to the V bombers, which were, together with guided missiles and the development of atomic weapons, a major part of the post-war defence programme. Similarly, the Americans, while having pushed their propeller driven designs as far as feasible, were also busy designing jet bombers in the 1940s and 1950s, culminating in the B52, still in service.

In post-war Europe, the strategic focus for the Western Allies switched very rapidly from Germany to Soviet Russia. The Soviet Air Force was also a formidable fighting machine, although it had evolved along lines more tactical than strategic. It had, on the drawing board, some impressive interceptor aircraft such as the MiG 15.

The first rocket powered interceptor of all was the German Me 163, which was used in the latter stages of the war against the high-flying daylight bombing raids by American B17s. It was small and simple, using a wheeled trolley for take-off and a skid for landing. Its endurance was extremely limited, but it had, by the standards of the time, a phenomenal rate of climb. However, despite its impressive performance, it had very few ‘kills’ credited to it – one source gives a total of nine.1

But the Me 163 obviously impressed the British Air Staff, and proposals for a very similar aircraft began to emerge in the late 1940s. The designs being considered were for a very similar aircraft: a rocket motor with no other means of propulsion, a simple skid for a dead stick (i. e., unpowered) landing, and a battery of unguided 0.5 inch rockets. It was intended for point defence, for airfields and the like. With its limited endurance, it was not suitable for much else. Such an aircraft would have been able to carry enough fuel for only three or four minutes powered flight. In effect, it was almost a manned guided missile, and the unpowered landing technique would not have made it popular with pilots.

In 1945, the whole strategic equation had been rewritten with the advent of the atomic bomb. There was no great urgency for the rocket interceptor in the immediate war years, since the Russians had built a formidable tactical air force, but had almost nothing in the way of heavy bombers. In addition, at that time it was thought that the Russians would not have atomic weapons until the mid – 1950s. In the event, the first Russian fission bomb was exploded in 1949.

A further difficulty to the problem of interception was that any jet atomic bomber would be flying very high, very fast. Up until the 1960s, the bomber’s best defence had always been height. The higher the aircraft, the more difficult it is to detect, the more difficult it is to hit with conventional anti-aircraft shells, and the more difficult it is to intercept. For interceptor fighters, the choice was either to loiter at high altitudes, which, given their limited endurance, was not usually a feasible option, or to reach these heights as quickly as possible. In the 1940s, the performance of the jet engine was not sufficient to do this. The problem was to get an interceptor to that height quickly enough and with a sufficient speed differential to be able to manoeuvre into a position in order to be able to attack. It was further realised that such an attack would probably be made by guided weapons of some form – either heat seeking, using infra-red sensors, or radar controlled.

There was a fundamental problem with an aircraft as small as the proposed rocket interceptor, in that it would have been able to fly only in daylight and reasonably good weather, and this problem would plague all the designs until the later P177 and F155 designs. It is curious, given these limitations, that there was so much interest in the design. When Churchill was returned to government in 1951, he took a personal interest in the project, asking Lindemann, his scientific advisor and iminence grise, to look further into the idea. But the RAF strategic offensive had been entirely night based, and the RAF had rarely encountered the Me 163, and knew of it mainly by reputation. Similarly the German offensive against the UK had been mainly night-based after the early attacks in 1940. It was only the Americans, with high-flying well-armed Flying Fortresses who attacked during the day. So why were the RAF so interested in a fighter that could be used only in daylight? One answer, of course, is the defence of the airfields where the V bombers would be based – effectively point defence.

But despite this, the Air Ministry issued OR 301. The main points of the designs requested were that they should be relatively simple and would use rockets for the main propulsion. However, quick calculations would show that the endurance of such an aircraft is extremely limited. Let us do some order of magnitude calculations.

Given a rocket motor with an S. I. of 200 seconds and mean thrust of 4,000 lb (the Spectre was rated at up to 8,000 lb thrust, but could be throttled) then the fuel consumption is around 20 lb per second. Given that the aircraft might carry

6,0 lb of fuel, this gives a powered flight time of 300 seconds or 5 minutes! This is not long in which to take off, intercept and shoot down an incoming aircraft at an altitude of almost 10 miles.

There are other problems too: high-speed, supersonic aircraft make very poor gliders! If the pilot’s interception takes him too far from his base, then he will be forced to eject. Similarly, every landing will have to be one chance only. Landing such an aircraft unpowered would be a pilot’s nightmare. It soon became obvious that an auxiliary turbojet would have to be fitted. This extended the post­interception phase and enabled the pilot to ‘go round again’ if there was a problem on landing.

But there can be other criticisms of the basic concept. The OR stated ‘in order to facilitate ease and speed of production, the aircraft and its equipment are to be as simple as possible.’ This, however, was a mistake. Although it is very tempting to go for a simple design on these grounds, any such design would have some fatal flaws. The first is that there was no inbuilt air-to-air radar, which would have been no novelty in 1952, and the lack of it would be a severe handicap for high-flying interceptor aircraft. It can also be argued that, owing to the limited nature of the OR, obsolescence was inevitable. The aircraft would be restricted to ground control and daylight interception. Would ground control be readily available in a nuclear war scenario?

Again, to quote from the OR:

Current day interceptor projects are expected to be adequate in performance to match the enemy threat in normal circumstances, but may be unable to destroy enemy aircraft carrying out special operations at exceptional heights.

An aircraft to fulfil this requirement must have an outstanding ceiling and altitude performance. So far as is known at present, the characteristics can only be provided by rocket propulsion, and, although aware of the probable operating limitations of this method, the Air Staff consider that the promise of tactical advantage more than outweighs other considerations.

It is surprising in other ways that the OR was put in this way. As mentioned, Bomber Command throughout the Second World War carried out the vast majority of its raids at night. It is unlikely that the Russians would attack by day, knowing how vulnerable such an operation would be with the advance warning that would be given as the bombers crossed the width of Europe. So OR 301 was in danger of becoming a requirement for an interceptor without a target.

But another key phrase is, of course, ‘special operations at high altitudes’. This was an oblique way of referring to the nuclear armed bomber, and there is one crucial difference between a conventional and a nuclear bomber. With conventional bombing, it is accepted that most of the bombers will get through the defences. Indeed, during the Bomber Command offensive, the German defences would be congratulating themselves if they inflicted 10% losses on a night’s raid. In nuclear terms, this is completely reversed. Even 90% losses on a bomber fleet could mean devastation wreaked by the remaining 10%. This was the philosophy behind the rocket interceptor.

In any event, designs were sought from all the major aircraft firms – Blackburn, Westland, Fairey Aviation, Saunders Roe and Bristol, among others. Saunders Roe were not originally on the list, and given their previous work, this is not surprising. However, they had gained experience of modern aircraft with the SRA1, a jet-propelled flying boat fighter. Bizarre though this concept might seem (it was intended for the Pacific war against Japan), it had two axial flow turbo jets, and, given the limitations on the design posed by its aquatic role, had a very respectable performance.

These designs were passed through to RAE to ‘score’ them on a complicated points system. The two that fared best were the Saunders Roe P154 and the Avro 720. The basic difference between the Avro design and the others is that Avro chose liquid oxygen and kerosene as fuels, as opposed to HTP/kerosene. The Gamma and the de Havilland Spectre rocket motors were the HTP choices. HTP was undoubtedly safer in a crash, although any rocket aircraft was inherently dangerous, owing to the explosive nature of fuel and oxidant.

But the limitations of these designs became obvious. Saunders Roe then came up with the suggestion that the aircraft should carry an auxiliary jet engine and have proper landing gear. The point of the jet was to supplement the rocket, and then to provide a limited cruise facility, followed by a return to base. The jet engine was of relatively low thrust compared with the rocket, but had high endurance. The Spectre was of 8,000 lb thrust; the Viper jet engine of 1,850 lb. This suggestion was also under consideration by the Ministry, and so Saunders Roe produced modified designs. The SR53 design then emerged from the various proposals.

Avro and Saunders Roe were instructed to build three prototypes each, before the first of many defence economy axes fell. The projects were put on hold. Eventually the Avro prototype, though nearly complete, was to be dropped. Saunders Roe was asked to build two prototypes of the F138D/SR53 (the first designation was the Ministry code for the project, the second was Saunders Roe’s).

Saunders Roe pressed on with further designs since the SR53 was felt to be too limited. Saunders Roe proposed the P177, with a much more powerful jet engine, and limited Air Interception capabilities, in other words, a radar set mounted in the nose. Both the RAF and Navy were impressed with this design, and for once, the two Services were in full agreement over a project. The P177 was given the go-ahead and Saunders Roe were asked to produce an initial 27 aircrafts. The two prototype SR53s were proceeded with so as to give experience with the concept.

The Air Staff went further and issued another requirement for a rocket assisted interceptor, F155, with an even more demanding specification. A number of proposals were put forward, with the ‘winner’ being a development of the Fairey Delta.

A variety of factors led to the cancellations of the P177 and the F155. The main reason, although not the commonly accepted reason, was a change in defence policy. At that time, the decisions about future defence projects and related policy were taken on the basis of reports by the DRPC, the current chairman being Sir Frederick Brundrett. The work that had been done over the past ten years on guided weapons, or surface to air missiles, was reaching fruition in the form of the Bloodhound missile.

Bloodhound was a remarkably successful missile, with a range of over 50 miles, being deployed in British service between 1958 and 1991. It was also deployed by Australia, Singapore, Sweden and Switzerland. Not only could it do the same job as the rocket assisted interceptors, it could do it a good deal cheaper. It costs a good deal less to maintain a squadron of missiles sitting on an airfield for ten years than it does to maintain and fly an equivalent squadron of manned aircraft.

There was also another reason for dropping the rocket assisted fighter: conventional jets with afterburners gave a performance not far short of the rocket. The English Electric P1, which went into the service as the Lightning, had a performance nearly as good as the P177. It too suffered from endurance problems!

Almost coincidental with this change of policy came a change of Prime Minister, when Eden resigned to be replaced by Macmillan. Macmillan wanted defence economies, and with that in mind, appointed Sandys as Minister of Defence. Very soon after the appointment came the 1957 Defence White Paper; indeed, so soon that most of the policy must have been established prior to Sandys. The 1957 White Paper became famous for three points: the abolition of National Service, considerable cuts in Defence spending, and cancellation of various aircraft projects in favour of missiles. On closer examination it is difficult to see how many other projects other than the rocket interceptors were cancelled, but it produced a considerable psychological shock to the British aircraft industry. There was a strong sense that there would be ‘no more manned aircraft’ for the RAF.

So despite a bitter rear-guard struggle fought by the Minister of Supply, Aubrey Jones, the P177 was cancelled. The Admiralty in particular pressed Sandys hard, and forced him eventually to admit that although the Navy still needed the aircraft for its carriers, the Defence Budget could not afford it. Both Saunders Roe and the Ministry of Supply tried hard to sell the aircraft overseas: there was Luftwaffe interest, and Saunders Roe prepared brochures for the Australian and Swedish Governments. However, Brundrett was against even this idea, arguing that we were trying to sell an aircraft which was obsolete, and that the Germans would be better off buying missiles from the UK. At the end of 1957, the Germans decided not to buy the aircraft; instead, they bought the Lockheed F-104 Starfighter, which became notorious in later years for its accident rate. Lockheed also had rather persuasive selling tactics unlikely to be matched by a small firm on the Isle of Wight!

The Lightning interceptor remained after the 1957 White Paper: later marks had almost the same capability as the P177 (and the same weakness in terms of endurance). It also showed the usefulness of a manned aircraft in the many interceptions carried out along the north and east coasts of the UK against long – range Russian aircraft probing British air defences.

Both the Lightning and the P177 fitted the specification for which they were designed more than adequately: the problem was not with the aircraft but with the specification and the changes in both technology and policy as the Ministry of Supply lumbered through its slow development procedures.

The apotheosis of the concept of the rocket interceptor was a design submitted by Saunders Roe for the Air Staff requirement F155. Saunders Roe’s design brochure was very impressive, leading to a behemoth of an aircraft with two jet engines with reheat and four rocket motors. This was an interceptor capable of taking on anything. It was also immensely huge, rivalling in scale even the TSR 2. Indeed, its size was to be its downfall. The original specification had been for an aircraft to carry two infra-red guided missiles and two radar guided missiles. Issue 2 specified one type or the other, with an option to switch. But whereas the other firms submitted their modified design, Saunders Roe stuck to their leviathan, and it was promptly discarded by the Ministry on grounds of size and expense. Fairey and Armstrong Whitworth were the chief contenders, with machines half the size, but again the project was never completed, falling foul of the same change in defence policy.

So the end result of all the work was the two flying prototypes of the SR53, and these were never to be anything other than research machines. But more than anything else, the concept had proved fatally susceptible to ‘mission creep’ over a period of ten years, from an extremely simple, almost crude, initial concept, to a highly sophisticated final series of designs. There is a saying, attributed to Voltaire, that the best is the enemy of the good (‘Le mieux est l’ennemi du bien’). If the RAF had wanted a good point defence high-flying interceptor, it could have had such a machine with 50 or so SR53s by the late 1950s. The concept of the rocket interceptor never had a chance to prove itself, partly because the window of opportunity in the technologies available was relatively narrow. This window was never fully utilised by the often slow progress of Operational Requirements through the Air Ministry, Ministry of Supply, the budget limitations and the desire to go one better as each design became finalised.

Rocket motors did have their drawbacks in the form of relatively limited operating time and use of exotic and expensive fuels. Handling such fuel would have produced difficulties when servicing the aircraft, and even though HTP is reckoned to be relatively benign as far as rocket fuels go, it is still hazardous to handle.

The other factors leading to cancellations were the enforced defence economies, the constant improvement in jet engines, and the development of guided weapons. The role of interception was to be taken by the Lightning aircraft, which although it too had an impressive rate of climb to altitude, was also limited by range, at least, in the earlier marks. But it was the advent of guided missiles, principally Bloodhound, deployed along the East Coast V bomber bases and at RAF bases elsewhere, which finally killed off the rocket interceptors.

However, one further major question is left unanswered. The motives of the Services, the Ministry of Aviation, the Air Ministry and the Treasury appear obvious enough. What is not obvious is why the Ministry of Defence and Powell himself took the position they did.

There are several possible scenarios.

The first is that Powell himself, possibly in concert with other senior civil servants in other departments, felt that the project was insupportable. Although he did not have the authority himself to cancel it, he could set up circumstances that gave others the opportunity. Thus if the Treasury and the Chiefs of Staff were to object sufficiently, then the new and relatively inexperienced Minister, fresh to the Cabinet, had little choice. It is interesting that the major attack on the project was only mounted after the October 1959 election, when Sandys was moved from Defence to Aviation. It would also mean keeping the details of the report from Sandys at the Aviation ministry for as long as possible, which seems to have been the case.

Another possibility lies not with Powell but with Watkinson and Macmillan, as indicated in the Daily Mail article. Under this scenario, Watkinson is appointed by Macmillan with a specific brief to ensure the cancellation. But why would Macmillan want to do this?

A possible answer lies not in the cost, but the timing of the cost. Expenditure on Blue Streak would reach its peak from 1960 to 1965. Although expensive in terms of capital cost, its running costs were (or appeared to be) extremely low. Both Skybolt and Polaris were considerably less expensive to buy (the development costs would have been covered by the Americans) but their running costs were very much higher. Flying aircraft, or running submarines, does not come cheap. However, these running costs would not have been incurred for several years to come, which would be well beyond the lifetime of the Macmillan Government.

A further answer might lie in the silos themselves. It is curious that the estimates of the vulnerability of the silos were never questioned one way or the other. Although the Air Ministry and the Ministry of Supply had done the calculations as best they could, the design was still a paper one (indeed, the design of the lid, one of the most crucial points in any silo design, had not been finalised by the time of the cancellation). In a sense, this makes a nonsense of the whole argument: since no one actually knew the exact strength of the silos, the debate was in many ways so much hot air. But they would raise political difficulties. They would certainly consume a great deal of civil engineering resources, and the political impact of such large and controversial structures in Conservative constituencies should not be overlooked. Indeed, the Home Office under Butler had come into the argument at one stage, requesting that the silos be situated on the east side of the country so that, given prevailing westerly winds, fallout from an attack would to taken away from the UK. In addition, for Civil Defence purposes, Butler wanted the sites well away from centres of population.

But however well-disguised the real reasons were, and no matter how much the papers conceal the true motives, a very revealing letter was written a year after the cancellation. A Technical Sub-Committee was to be set up for the BND(SG), and Zuckerman wrote to various eminent scientists, inviting them to join. One was Sir Robert Cockburn, who had been working for the Government in various capacities since the war, and at one time had been CGWL at the Ministry of Aviation. He wrote back to Zuckerman, and one paragraph of his letter reads:

Blue Streak was cancelled because it was not politically viable rather than because it could be pre-empted. The scale of pre-emption was admitted to be of the order of

3,0 megatons. Supporters of the system argued that this was so excessive that pre­emption could be ignored in practice. The argument was not accepted and vulnerability was advanced as the main reason for cancellation. The real reasons were more fundamental although still not clearly appreciated. I suggest no British
statesman could visualise exploiting a deterrent threat which if mishandled could only lead to the annihilation of the whole country; nor could he believe that a threat involving such consequences would be taken seriously by an opponent.25

In other words, once missiles are fired, they cannot be recalled. And with missiles, which are seen as potentially vulnerable whilst on the ground, the incentive is to fire early. Bombers can be recalled, and they do not need to fire off their missiles until it is certain the UK has been attacked. The same is true of submarines lying undetected in the Atlantic. This, probably more than anything else, reflected the true reason why Blue Streak was cancelled.

The cancellation is a graphic example of how Whitehall can work. What is of more interest is the study of how much policy was made by officials and how much by Ministers. Ministers rely on officials for advice: how impartial was that advice? Civil servants themselves have opinions. Furthermore, the documentary evidence that survives tends to suggest that a good deal of policy was not made on paper, but in briefings, and that papers were presented with a particular pre­determined slant or viewpoint (although there is nothing new in that!). Ultimately, it might be said that the correct decision was made, but that the evidence presented was misleading, and the motivations of the various participants were, to say the least, often concealed.

Two stage. Launched 24 May 1960 at 21:00. Apogee 350 miles.

BK08, the first two-stage vehicle to be fired, was intended to obtain re-entry of the head at a higher speed. Main stage performance was good, but the second stage did not separate from the main stage and so was not ignited. The failure of explosive bolts or inertia switch circuitry was the probable cause. The trial, however, proved the aerodynamics of a new configuration, the control stability with the heavier vehicle, the stressing with greatly increased forward weight and the necessarily modified guidance arrangements.