General Review of a Space Flight Programme based on Blue Streak by Geoffrey Pardoe
From The Space Library
This article is condensed from a paper, given at the Commonwealth Spaceflight Symposium in London in August 1959 by Mr. G. K. C. Pardoe, Chief Co-ordinator (Ballistic Missiles), de Havilland Propellers Limited.
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Introduction
THE intention of the British Government to participate in space flight to some degree became evident at the time of the Government statement on this subject in May, 1959. It is the intention in this paper to discuss the possibilities which exist within the British Commonwealth for major participation in space flight in the future, as the next logical step to the early phase of passive participation, whereby instruments are merely carried into space by means developed outside the Commonwealth.
In this country we have already embarked on a military ballistic missile project, aimed at producing a weapon in the same class as those military vehicles already used in the United States and Russia in the role of the first stages (and even upper stages) of space flight vehicles. The existence of our military project in the United Kingdom is already of prime importance, in that many new problems have had to be overcome, and in doing so, valuable experience has been gained which will inevitably yield great benefits when applied to equipment in everyday use; this is particularly true, of course, in the field of electronics and aviation. In addition, there is the added attraction that major direct commercial applications are already within sight as a result of projecting equipment into space: the 24-hour satellite is a well-quoted example of direct application to telecommunications, but this is by no means the only solution here, as a pattern of satellites revolving closer to the earth may well have better use than the unique 24-hour orbit.
Commonwealth Participation
There is not the slightest doubt that the production of a system to achieve space is a major and costly undertaking, and that the effort which has to be mounted to produce the total system can only at present be supported by one of the leading major powers in the world. Not only is it a question of finding the large sums of money to finance the work, but also the possession of the necessary technical skill—and, of course, there is the geographical requirement. There must be a base and space to launch the vehicle, and full benefit can only be obtained from space experiments if suitable tracking stations are established at key positions around the world. Fortunately there has been a good measure of co-operation between all countries so far associated with space flight, but this co-operation must be considerably improved and strengthened if we are to learn the most from our experiments. The British Commonwealth has a tremendous advantage in its terrestrial coverage: in addition to the launching sites already being built at Woomera, Australia, there are several desirable places at which space vehicle launching sites could be established with great advantage; also, to track vehicles, the Commonwealth territory can, and already does, provide unique facilities. The well-publicised radio-telescope at Jodrell Bank is an important United Kingdom tracking facility. There has been an important base established at Singapore which provides valuable tracking information already, and, of course, in Australia, too, equipment has been established to play an active part in space exploration. Britain and Australia are already busily engaged in the construction of the Blue Streak ballistic missile system and its associated testing and launching sites, and in Canada there is a large amount of experience on guided missiles and aircraft — Canada, it is reported, has already indicated its interest in participating in space experiments. We have then, the nucleus of the required effort firmly established within this group of nations, with the potentiality to expand this in many directions as required.
Objectives
Consideration of the objectives will be limited to the first few targets on which an early programme could be based; moreover, planning for this work cannot be done in a vacuum, and it is most important to consider our plans in relation to the overall intentions and programmes of both Russia and America in their exploration of space. Both of these nations have demonstrated remarkable achievements so far; therefore it is important to consider what we, as late starters, should usefully plan to do. The important thing to realise about space exploration is that it is not to be treated as a race; obviously there is a first time that the escape velocity from Earth was reached, a first time for orbit round Mars, etc., and considerable national prestige results from achieving these " firsts." Such a race-track would not be across a flat field when it comes to space exploration, but rather across the surface of a sphere — there would be no finishing line, and an infinite distance to be covered. The important thing, of course, is not to collide with other contestants whilst this ground is being covered, and it is for this reason that we must consider the directions that other people are taking, before making our plans.
Inevitably, Russia and America will constantly strive to match each other's major achievements since, for one thing, they are in a position to compete, and there is a wealth of information and prestige to be gained by so doing. However, space exploration is an expensive business, not only in money but in facilities, and by concentrating efforts on these extended missions, many zones of interest, of a less glamorous nature, will be left comparatively unexplored. The best returns do not always come from the most exciting investments, and by equipping ourselves with a means of moving in terrestrial, cislunar and translunar space, we should be covering the zones of interest most likely to be of direct value to the earth's inhabitants for many years to come.
This is an attempt to demonstrate, therefore. that the real zone of direct interest for decades to come is between here and the moon, and that if one can anticipate moving in this zone in that period, then this is a worthwhile objective. In fact, taking the argument one stage further, one might successfully reason that the zone, from the surface of the earth to 22,000 miles above it, was the highest productive region for a long time to come.
It would seem, then, that both from considerations of what the vehicle should do, and could do, a series of experiments might be planned whereby equipment is projected into orbits round the earth, the lowest of which might be about 50 nautical miles and near-circular, and the highest of which might well be a very elliptical orbit encompassing the moon. It would not be possible within these first broad objectives to expect to land on the moon and return to earth (unless someone very kindly supplied a large refuelling satellite around the earth before Blue Streak finishes its useful life as a space vehicle!). To talk of commercial application anywhere at this stage sounds attractive, but in the immediate future really one embraces the thoughts of producing improved communications (both video and audio), as well as weather recording; the latter, in certain parts of the world, can be translated directly into saving of vast sums of money, life and property by anticipating violent weather conditions. Again, it is not the purpose of this paper to discuss in detail all of the returns one might expect from venturing into this work.
Briefly recapitulating, therefore, it is being suggested that it is worthwhile planning to send payloads — in the order of hundreds of pounds of weight — into various earth orbits between here and the moon, as a very important first series of objectives in a long-term space flight programme.
Statement of the Problems
The most important fact to understand about a space vehicle is the extent of the total system which must be developed to enable extraterrestrial flight to be realised. By this is meant that the day of producing a flying machine, which can take off from a variety of airfields, is passed; the ballistic missiles and space vehicles are to-day specifically designed to be integral with their launching facilities. Every different ballistic missile to date has a different means of holding and releasing the vehicle on launch, and the gear to do this is specifically designed in association with the autopilot, control propulsion and structural criteria of the missile, and the gear must also be firmly integrated with the pad design. The launching complex itself contains a very formidable array of preparation and check-out equipment, all of which is specifically related to one form of missile. Different vehicles have different pre-launch count-down procedures, start sequences, propellant supplies, pressurisation levels, power requirements and so on, and although the ground equipment is more of a permanent investment than the airborne equipment, in many cases considerably more effort needs to be expended in designing, developing and producing this equipment than for that in the missile. The moveable servicing towers, which are offered up to the missile when erected on its launcher, are a very large and important part of the launching equipment, and must be tailored to fit the contours of the missile, as well as providing the appropriate services at the appropriate levels. These towers are massive pieces of equipment, often 100 to 150 feet in height.
With such a wide array of equipment required, therefore, it is obviously sensible to use as much of it as exists already (with some necessary adaptations), as this will not only provide the most economical means of achieving one's objective, but also will take advantage of the development and the reliability which will be built into equipment already in use. It is important to note that the majority of the equipment is required for the first stage, which is already in existence by virtue of the military project which requires it.
Vehicle Performance Requirements
For the purpose of this exercise, let us consider the possibilities of placing a payload in a nominally circular orbit 300 miles above the surface of the earth. Compared with a north-south polar orbit (in other words, still earth conditions), for the same total energy, 15 percent increase in mass of the total hardware in orbit can be achieved by a due easterly firing (thus taking advantage of the earth's rotation effect). This is in comparison with a 15 percent reduction of mass in orbit (compared with the still earth conditions) if a due westerly take-off is considered. If one can achieve a trajectory in a north-easterly quadrant this gives a bonus of approximately 10 percent mass in orbit compared with the still earth condition. Unless otherwise stated, all figures in this paper will he related to this.
Vehicle Configuration
The advantages have been stressed of using as much existing equipment and facilities as possible, in the first stages of participation in space flight, and so to start with in this discussion you will see that the first stage of our space vehicle is a substantially unaltered Blue Streak missile.
It is fully appreciated that the greatest concentration of energy should be incorporated in the upper stages, and that an optimum design would make use of exotic high energy propellants, so in considering contemporary equipment we are not presenting the best performance that can be obtained. Clearly, within the velocity requirements discussed earlier, either a two- or three-stage vehicle, plus payloads, may be considered as solutions to the performance requirement. Aiming at simplicity in the first example, let us consider what might be obtained by the use of a simple solid second stage to Blue Streak. The second stage is formed by a twin solid rocket motor propulsion unit, each of the rockets being based on an existing design of motor. Instead of the more orthodox location of the payload at the head of the propulsion unit, one might divide the payload into two canisters located in the manner shown, indexed with the twin motors. This gives convenient packaging of the second stage and payload, and a more compact configuration. Clearly, alternative locations of the payload can be chosen if required. There is nothing new or clever about this proposal for a simple solid rocket second stage. The most important feature of it is its early availability; if we assume that the total weight of the second stage and payload is in the order of 8,000 lb., then a suitable velocity increment from the motors could be obtained allowing an actual payload weight of about 1,000 lb., and so we reach a conclusion that the existing Blue Streak missile — with virtually no mechanical or system changes — together with an extremely simple second stage based on equipment already under development, is capable of placing a payload of some 1,000 lb. in a 300-mile circular orbit around the earth! It would not be sensible to embark on a comprehensive space programme based on the limited capability of a solid rocket second stage only, when far more potentiality exists by the use of a more efficient liquid fuel second stage. The solid second stage would just be an early means of getting a payload into space during the interim period.
Staying on the theme of availability, consideration immediately turns to the use of the Royal Aircraft Establishment test vehicle — Black Knight — as a possible second stage for Blue Streak. The figure shows how this combination might look when used as a two-stage vehicle with a nominal payload shown on the front. A fair amount of information is publicly available now on the Black Knight vehicle, and it will be recalled that in its basic state it has a quadruple chamber rocket motor system, using H.T.P. and kerosene as propellants. Each of the four chambers produced 4,000 lb. thrust at take-off, giving a combined take-off thrust of 16,000 lb., and this total thrust rises to over 18,000 lb. outside the atmosphere. Normally its length is some 35 ft., and its maximum diameter is 3 ft. The distribution of the propellant tankage is as shown in the diagram, with the H.T.P. to the rear and the kerosene forward, with a small bay containing pipe-work, reducing valves, etc., in between the two tanks. The guidance and control equipment is located in a short bay in the forward end of the kerosene tank, in the front of which the various types of payload can be installed.
It has been suggested that this payload could be about 1,000 lb. in weight. This load is well within the capabilities of Blue Streak to carry it off from the ground, and this combination looks quite attractive. Its main merit, of course, is that the second stage is already in existence, and is demonstrating a remarkably high state of reliability. By the time it would be used as part of a space vehicle, the propulsion system should be in a very well developed and reliable state.
At the stage we are in at the moment, when we may be about to embark on serious space vehicle production, it is obviously essential to consider the largest and most efficient second and third stages which could be carried aloft by the only first stage available, i.e., Blue Streak. In this respect improvements over the basic Black Knight should be investigated, since the latter in its present form, is much smaller and lighter than the take-off boost capabilities of Blue Streak; so whilst there is great merit in the availability and reliability of Black Knight it does fall short of the ideal size and thrust characteristics in relation to its main stage.
There exists, however, a very attractive alternative whereby the best of both worlds might be combined: the focal point of a requirement for a good second stage is an accurate and reliable propulsion and control system. The complete propulsion bay of Black Knight is an extremely well-engineered piece of equipment, and it is suggested therefore that this bay should be taken complete and used in association with a modified tankage. Such a deviation from the basic Black Knight would incur the minimum risk of development trouble, since a change of tankage shape need not be critical. Two hemispherical tank domes would be fitted end-to-end, their separation by a parallel section of tank being determined by the limiting volume (and therefore weight) which can be lifted by Blue Streak. The same maximum diameter as Blue Streak is thus produced in the second stage, and on consideration of the division of volume within the tankage of the second stage to allow for the H.T.P./kerosene burning ratio, it is suggested that the more orthodox lateral separation diaphragm could well be replaced by a longitudinal cylindrical type diaphragm, as shown. The kerosene, being the smaller volume, could be contained within this central tube, and the H.T.P. could be in the outer torroidal container. This has been lightly referred to as a "doughnut " configuration. A higher pressure would obviously have to be maintained in the kerosene tank than that in the H.T.P. tank, to avoid compressive stresses on the central tube, but the pressures in both tanks are comparatively small, and this should present no problem. Some care will have to be taken in the design of the attachments of the ends of the kerosene tank to the domes of the H.T.P. tank to allow for appropriate flexibility, but here again it is suggested that the rear end of this kerosene tank could be made to the 3-ft. diameter of the Black Knight propulsion bay, and the axial loading between the propulsion bay and the forward bay leading to the payload could be effected through this kerosene tank wall, assisted, of course, by pressurisation of the H.T.P. tank.
Taking, for example, the 300-mile circular orbit which we have discussed earlier, calculations based on the increased tankage indicate that a payload mass of some 2,000 lb. could be expected. This represents a substantial improvement over the 1,000 lb. suggested for the Black Knight combination, and it may well be that the added development work necessary to make and prove the different tankage, compared with the Black Knight vehicle, would be justified. Bear in mind, too, that the manufacturing technique of this new tankage would be based very closely on that already experienced on Blue Streak. Looking ahead a little further, should it be necessary or desirable to fit a significant third propulsion stage, in order to project a smaller payload into a deeper probe, then it would seem comparatively simple to fit such a third stage on to the top of this " doughnut " Black Knight second stage. Again the arrangement is shown in this diagram, where a simple single solid rocket third stage is arbitrarily taken for convenience.
Summarising, therefore, there would seem to be a good potential performance available from the use of this modified Black Knight, whilst at the same time maintaining the basic knowledge and reliability obtained from the extensive Black Knight trials. No new manufacturing techniques are involved in this proposal, and yet a more compatible multistage combination is offered, involving less alteration to ground support equipment such as the servicing towers; perhaps most important of all, it offers almost double the payload capability when used with the unaltered Blue Streak, compared with the basic Black Knight proposal. Good advantage could be taken of any increased performance which became apparent on the basic Blue Streak configuration in the design of the second stage (for example, larger thrusts available from the main stage engines, etc.) The structural and dynamic compatibility problems between the two stages would be easier with the shortened second stage. Nevertheless, extra work is involved, and Black Knight as it stands is an attractive proposition.
Moving further on, in the investigations, one notes that the thrust available from the Black Knight propulsion system is not ideal when used in conjunction with the Blue Streak main stage. However, to contemplate developing a higher thrust propulsion system for the second stage (certainly with liquid propellants) would be departing from the basic assumption made at the beginning of this paper, that first consideration would be given to equipment already in existence and being proved in the United Kingdom. Other than stating that even larger payloads and performance could be gained by designing an optimum second stage for use in relation with Blue Streak, no further detailed consideration to these more advanced developments will be given here. The point is made, therefore, that the payloads which we have discussed here are by no means the limit—something in the order of just over a ton may well be the maximum capacity of Blue Streak as a first stage.
Briefly summarising now, these different stages which might be used to produce a space vehicle; at one extreme, the simple treatment—with limited capability—using a solid rocket system able to place, say, 1,000 lb. in a 300-mile orbit. At the other extreme, we have a more elaborate liquid propulsion system second stage based on existing equipment, able to place a payload of some 2,000 lb. in orbit at 300 miles altitude; between these two we have a half-way stage where Black Knight in its present form (and thus readily available) could be used to place about 1,000 lb. in orbit at 300 miles. Obviously, these three suggestions are not the only solutions — even within the criterion of not developing a new propulsion system. Clusters of solid rockets could provide a reasonably high payload potentiality, but a short study reveals quite easily that the higher motor casing weight associated with the solid rockets, and the lower S.I., offers a far less efficient solution to the problem than the ones suggested here. Lastly, the performance potentiality of Blue Streak as the first stage could be used to the limit if one was prepared to develop or buy from elsewhere a larger liquid propulsion system than that at present available in this country.
Organisation, Cost and Time-Scale
A discussion of the time-scale of such activity is obviously a very delicate subject. So much depends on which objective is chosen, the amount of effort that a government may wish to invest in furthering such work and, not least of all, on the progress of the ballistic missile project on which this discussion is based. Obviously, I can say nothing of the latter, other than to say that several Blue Streak vehicles are in evidence at test sites, and have been for some time, and that the first flight trial of the system cannot be far away in the future. The Blue Streak military project must not suffer in the slightest way in order to enable a purely scientific project to go ahead — although this situation could, of course, be affected if primary military space flight objectives became apparent. Furthermore, a stage must be reached where the production of vehicles for the ballistic missile military programme could be increased to provide the extra vehicles for adaptation to this space flight programme. Such vehicles should have passed the test of demonstrating satisfactory guided flight with the full system.
Taking all these factors into consideration we are clearly two or three years away from such a date at which these proposals might materialise. Of course, as always, a situation such as this may change for better or for worse, and if appropriate steps were taken, this period could possibly be advanced. Within this time-scale it would seem quite conceivable to do the necessary modification, planning and construction work on Black Knight, and it also seems a very reasonable period in which the necessary payload could be designed and assembled, and indeed tested, if a decision should be taken to use American-launched equipment in the early stages. However, from the Government statements on this subject, it would seem that the American vehicle (suggested as Project Scout) would only be capable of sending a payload of about 150 lb. into space, and so only parts of the more important and elaborate British satellite could be investigated in association with these American sponsored experiments. It is also difficult to discuss the cost of such an undertaking. However, certain salient features should be mentioned: firstly, the whole concept discussed here could be based on the work done already for the Black Knight and Blue Streak projects. The proposals are all considerate of the need to minimise the changes to equipment to meet a space vehicle specification; some components of the vehicle — and in fact some of the major parts — are a continuation of production of equipment already in use for Blue Streak and Black Knight. The exception to this is, of course, the satellite payload, but this has been discussed already.
An investigation into the cost of achieving such a programme shows that the necessary national expenditure for such an important step is a comparatively small and reasonable amount, bearing in mind the implications to the future of our country.
Deliberately, little mention has been made in detail in this paper of the satellite or payload itself. The Government, as we know, have initiated a considerable amount of design study work on the form of this payload; this work is being carried out largely by Government Establishments and Universities throughout the country with, it is to be hoped, appropriate consultation with industrial experts. Given the advantage of single-mindedness of purpose, a British team could produce a worthwhile and reliable vehicle, of which the British Commonwealth could be proud. Properly designed and conceived, such a vehicle could take its place amongst the other similar projects already in existence in the world, and so place the British nation in a position where they need not be apprehensive at being caught in a situation where they can neither contribute to, nor contest, activity outside the atmosphere of this earth.
The existence of Blue Streak as a potential main stage vehicle for European countries is significant: assuming that the governments concerned would agree to such a move, European nations who do not possess a main stage booster facility, could well consider planning a programme using Blue Streak as their booster for either their upper stages or payload, since the design team of the vehicle would be on their doorstep. The leading technical establishments within Western Europe must surely seek to find an outlet for their astronautical and space researches (or more properly "Searches ") at some time in the future, and there are obvious advantages to be gained from planning their experiments in association with another European country.
Earlier in this paper, an attempt has been made to demonstrate that we as a nation are bound to embark on space flight at some time. In the time-scale which I have discussed, we would be 4 to 5 years late in our early experience of these new things — this must surely be relatively unimportant when we look back in 50 years time to the present age. What does seem vitally important is that, as a nation, and as individuals, we should have a firm plan and conception now of where we are going, and what we can do.
