In the early years of the American space program, the main task was to improve the characteristics of rocket and space systems. It quickly became clear that the increase in technical parameters was associated with significant difficulties and should lead to an increase in the cost of launches. An interesting solution to this problem was proposed in the form of the Big Dumb Booster concept.
Big Stupid Rocket
The projects of rocket and space systems of that time were distinguished by high technical complexity. To obtain higher characteristics, new materials were developed and introduced, promising samples of equipment of all classes were created, engines were developed, etc. All this led to an increase in the cost of developing and producing missiles.
Calculations showed that while maintaining such approaches, the cost of withdrawing cargo will remain at least at the same level or even begin to grow. To maintain or improve economic performance, radically new solutions at the concept level were required. The first studies in this direction began at the very end of the fifties and soon gave real results.
NASA, in collaboration with a number of private aerospace companies, has worked out several new concepts for advanced systems. One of them was called Big Dumb Booster - "Big stupid (or primitive) launch vehicle."
The essence of this concept was to simplify the design of the launch vehicle and its individual components as much as possible. For this, it was necessary to use only well-mastered materials and technologies, abandoning the development of new ones. It was also required to simplify the design of the rocket itself and its components. At the same time, it was necessary to increase the carrier, increasing its payload.
Initial estimates suggest that this design and manufacturing approach has enabled BDB to deliver dramatic reductions in launch costs. In comparison with the existing and promising carrier rockets of the "traditional" appearance, the new models were many times more economical. Production growth was also expected.
Thus, the BDB booster could quickly build and prepare for launch, and then send a larger load into orbit. Preparation and launch would have been at a reasonable cost. All this could become a good incentive for the further development of astronautics, but first it was necessary to develop and implement fundamentally new projects.
Fundamental solutions
Several organizations developing rocket and space technology participated in the development of the BDB concept. They have proposed and brought to varying degrees of readiness a number of launch vehicle projects. The proposed samples were noticeably different from each other in their appearance or characteristics, but at the same time they had a number of common features.
To simplify and reduce the cost of the rocket, it was proposed to build not from light alloys, but from accessible and well-mastered steels. First of all, high-strength and ductile grades from the category of maraging steels were considered. Such materials made it possible to build larger missiles with the required strength parameters and a reasonable cost. In addition, steel structures could be ordered from a wide range of enterprises, incl. from various industries - from aviation to shipbuilding.
A large rocket with a heavy load required a powerful propulsion system, but such a product itself was extremely expensive and complex. It was proposed to solve this problem by using the most efficient types of fuel, as well as by changing the design of the engine. One of the main ideas in this area was the rejection of turbopump units - one of the most complex components of liquid-propellant rocket engines. It was planned to supply fuel and oxidizer due to the increased pressure in the tanks. This solution alone provided significant cost savings.
The proposed materials and alloys ensured the construction of large structures with the corresponding potential. The payload of a Big Dumb Booster rocket could be increased to 400-500 tons or more. With an increase in the size of the rocket, the proportion of dry mass in the launch weight decreased, which promised new successes and additional savings.
In the future, rockets or their elements could be made reusable, which was facilitated by the use of durable steels. Due to this, it was planned to obtain an additional reduction in the launch cost.
However, to obtain real results, it was required to complete research work, and then launch experimental design. For all the seeming simplicity, these stages could take many years and require substantial funding. Nevertheless, the enterprises of the space industry took this risk and started designing promising "primitive" launch vehicles.
Bold projects
The first projects of a new kind appeared in 1962 and were evaluated by NASA specialists. These variations of the BDB were based on common ideas, but used them in different ways. In particular, there were differences even in the starting method.
The real record holder could be the NEXUS rocket developed by General Dynamics. It was a single-stage launch vehicle with a height of 122 m and a maximum diameter of 45.7 m with stabilizers in a span of 50 m. The estimated launch weight reached 21.8 thousand tons, the payload for launching into low-earth orbit was up to 900 tons. For other orbits, the carrying capacity was half the size.
The NEXUS rocket was supposed to launch the load into orbit, and then land in the oceans using parachutes and solid-propellant landing engines. After service, such a BDB could perform a new flight.
In the same year, the Sea Dragon project from the Aerojet company appeared. He proposed a super-heavy sea-launch booster, and it did not require any separate launching facilities. In addition, it was planned to involve shipbuilding enterprises in the production of such missiles, which have the necessary - not the most complicated - technologies for assembling metal structures.
"Sea Dragon" was built according to a two-stage scheme with simplified rocket engines on both. The rocket length reached 150 m, diameter - 23 m. Weight - approx. 10 thousand tons, payload - 550 tons for LEO. At the first stage, a kerosene-oxygen engine with a thrust of 36 million kgf was provided. Instead of a ground launch complex, a more compact system was proposed. It was made in the form of a large ballast tank with the necessary devices attached to the bottom of the first stage.
As conceived by the designers, the Sea Dragon rocket was supposed to be made by a shipyard from the usual "ship" materials. Then, with the help of a tug, the product in a horizontal position should be towed to the launch site. The launch system provided the transfer of the rocket from a horizontal to a vertical position with a draft of about half of the hull. Then the Dragon could start the engines and take off. The return of the steps was carried out with the help of parachutes with landing on the water.
Cheap but expensive
The projects of super-heavy launch vehicles Big Dumb Booster were of great interest in the context of the further development of astronautics. However, their implementation was associated with a number of characteristic difficulties, without overcoming which it was impossible to obtain the desired results. A sober assessment of technical proposals and projects led to the closure of the entire direction.
Further development of the proposed projects from Aeroget, General Dynamics and other companies was a very difficult task. To create a "cheap" rocket, large expenditures were required on project development and adaptation of existing technologies for space applications. At the same time, the resulting missiles in the foreseeable future were of no interest: any payload of hundreds of tons was simply absent and was not expected in the coming years.
NASA considered it inappropriate to waste time, money and effort on projects without real benefit. By the mid-sixties, all work on the BDB topic had ceased. Some of the participants in these works tried to remake projects for other tasks, but in this case they did not receive a continuation. To the delight of taxpayers, work on the BDB stopped early on, and little money was spent on the dubious program.
As the further development of American astronautics showed, heavy and super-heavy launch vehicles did find use, but systems with a carrying capacity of hundreds of tons were redundant, as well as overly complex and expensive - despite the original plans. The development of astronautics continued without the "Big Primitive Rocket" - and showed the desired results.
