View down through the center of the world's largest solid rocket shows rubberlike propellant charge framing two Aerojet- I General engineers as they stand between the center pair of the motor's segments. Rocket develops half million pounds thrust. The big solid-rocket program, a USAF responsibility, is now going to get its chance . SOLID BOOSTERS How Far Have We Come? How Far Can We Go? By J. S. Butz, Jr. TECHNICAL EDITOR, AIR FORCE MAGAZINE . S OLID rockets have now attained a really solid Today, the situation has been completely reversed. position in our space planning. The big solid rocket is going to get its chance. Devel- A year ago, few people familiar with the US opment of these boosters has been made an Air Force space effort would have bet much money that solid responsibility, and about $60 million has been pro- propellants would ever be used as "superboosters," de- vided to begin the job in earnest during this fiscal veloping upward of fifteen million pounds of thrust. year. All signs point toward a maximum-effort devel- By last fall, in fact, the large solid-rocket program opment program that will be pushed as fast as tech- apparently was stuck for good on the treadmill of end- nology will allow. less study and research. Several factors contributed to this sudden change Since Sputnik I opened the space age, the nation's of fortune. Yuri Gagarin's orbital flight in April—in solid-rocket experts had contended that multimil- which the Red flyer became history's first spaceman— lion-pound-thrust solid-propellant boosters would be certainly was instrumental. It changed the entire cheaper, more reliable, and ready sooner than large course of the US space program by overcoming the liquid-fuel boosters. These contentions had fallen on go-slow philosophy of President Kennedy's scientific deaf ears, however. Large solids remained in the "re- advisers. Strong elements in the Air Force had pushed search" stage. No plan existed to put them into devel- for development of large, solid-fuel boosters. But one opment. (Continued on following page) AIR FORCE Magazine • October 1961 33 SOLID BOOSTERS CONTINUED Probably Already Fired —Will Fire Under Study - 1 Before 1962 _ci 120 \ I II 110 ."‘E' 100 0 90 0 8: =2 80 _ci -01 0 '4; ru 70 0 0- in 60 50 172 40 C ai 30 20 10 A, IL UTC GCR UTC AGC AGC AGC AGC UTC Saturn Nova P-1 $S-B TW-1 FW-1 FW-2 P-2 Large motors similar to those oil the right above are the goal of the solid-rocket booster program. The biggest motor flight tested to date (extreme left) and the USAF - NASA series of experimental segmented motors are compared in size in this scale draw ing. In clusters of eight or more the Nova motor could serve as a booster for a multistage moon rocket. In smaller clusters Saturn motor, second from right, could replace the liquid-fuel Saturn booster, which is now in development. factor undoubtedly contributed more than any other ever, at budget time the paper proposals for solid-fuel to the rise of solid rockets. This was the fight that boosters have always been pitted against established solid-propellant manufacturers put up against the projects for large liquid-fuel systems such as the research" status they had been given by the National Saturn booster and the 1.5 million-pound-thrust F-1 Aeronautics and Space Administration, which was in engine. These have been in the works for several charge of all booster development until last May. years. These projects soaked up all of the available The solid-propellant companies carried their argu- booster-development money in the first three years of ments to the Congress and to the public in every man- the space age when urgency, parallel programs, and ner available to them. Company officials made in- technical insurance were not in vogue. Small sums of numerable speeches, appeared on radio and TV, and research money were then spread around to keep wrote or assisted with articles for mass-circulation promising ideas going for possible development in magazines. They clearly regarded publicity and public the future. education their main job in the fall of 1960 and early The solid booster was clearly lodged in the research months of 1961. As a result, Congress probably is as stage last fall. In the Eisenhower Administration's FY thoroughly briefed on the arguments for solid-pro- 1962 budget, $3 million was allotted for NASA to study pellant rockets as on any technical subject. Large large, solid-fuel rockets. Liquid-fuel rocket programs numbers of congressmen and senators on both sides on the other hand received more than $65 million. of the aisle are convinced that solid boosters offer a Congressional testimony showed that most NASA possible means of getting ahead of the Soviets in officials and liquid-propellant rocket experts from in- booster power. dustry believed that time was against the large solid In principle, no overwhelming technical opposition booster. The argument, in essence, was that the solid has been registered against large solids, even by the booster would eventually work but that it would take partisan supporters of liquid-fuel rockets. How- many years of research and development to bring it AIR FORCE Magazine • October 1961 to a usable state. According to this theory, the solid propellant in a solid rocket is of more interest than the booster would follow the liquid-fuel rocket booster thrust it produces. The weight of propellant charges into operational space use, just as the solid-fuel ICBM had been increased about nine times within seven followed the liquid. years, from the neighborhood of 5,000 pounds to about The change in Administrations last January brought 45,000 pounds. Solid-rocket engineers believed that no change in the solid-fuel booster situation. As Presi- the successful tests with 45,000-pound engines proved dent Kennedy's advisers reviewed the space program, that it was possible to go directly to single motors NASA asked for an additional $5 million in solid-rocket holding more than 700,000 pounds of propellant. research money, but this was refused and the appropri- • Most of the technical know-how needed to build ations request remained at $3 million. large solid rockets had been made available in the Intense congressional pressure in the wake of the Minuteman and Polaris programs. These two military first Soviet orbital flight succeeded in reversing the rockets have done more than anything else to advance picture. The solid-rocket booster now has the status the solid-rocket state of the art. When the Minuteman of a parallel development to the liquid-fuel booster and Polaris entered development, no one was abso- program. It is a backup for the ten-million-pound- lutely certain that they could be built. Their perform- thrust-plus, liquid-fuel Nova booster called for in the ance specifications called for propellant efficiencies Kennedy Administration's moon program. It is prob- and structural excellence that were not possible at the ably also the main contender for the military space time. Together they have caused the creation of a new booster role. solid-rocket technology. They have made it possible The hard sell has brought the solid rocket equal for the solid-rocket superbooster almost to equal the status, so to speak, but it has also given wide pub- over-all performance of a similar type liquid booster licity to a number of ambitious claims and predictions. using kerosene and liquid-oxygen propellants. The If they can be realized as soon as the solid-rocket in- performance advantage, but not the cost advantage, dustry predicts, then the US space program will would go back to liquids if liquid hydrogen and liquid receive an almost miraculous speedup. oxygen were used as first-stage propellants as now These predictions include: being considered. • Demonstration of the reliability of a 3.5 million- There is one major developmental unknown. It was pound-thrust booster, composed of a cluster of seven not solved in the Minuteman and Polaris programs. motors, within eighteen months, and its first flight test This is the mechanism for controlling the vehicle by in two years. moving the thrust vector. Many engineers believe that • Flight test of a first-stage booster of twenty-one gimballing nozzles will not be efficient on large motors. million pounds' total thrust, within thirty-seven to They point to small-scale experiments that show a thirty-nine months. With the program pushed to the fluid injected into the nozzle will cause the flow to maximum, the first flight, it is said, could take place cant. Others doubt the effectiveness of this method. within two years. These are questions that probably can be answered • Payload of the largest solid booster, when com- early in a development program. bined with the proper upper stages, to be two million • Clustering of large solid rockets is believed to be pounds in a 300-mile orbit, or about 600,000 pounds feasible on the basis of experience with the X-17 re- to the moon. search vehicle, the Nike-Hercules booster, and the The optimism displayed by all solid-rocket manu- Little Joe test vehicle used in the Mercury program. facturers was based primarily on four facts prior to Obviously the people in charge at NASA and all of May of this year. They were: the authorities in the rocket industry did not agree • Almost perfect reliability. Thiokol Chemical with these estimates of the state of the art in solid- Corp., as a typical example, could boast that their rocket technology.