Aggregat 4 (A-4)
 
 

 

German ballistic missile Aggregat 4 (A-4)
The A-4 ballistic missile was the world's first operational liquid fuel rocket. Development of the rocket engine for the A-4 was also be deviled with difficulties. The A-4 would need an engine of 25 tonnes thrust. Eventually, through a seven-year process of trial and error, a fuel-cooled rocket engine of 1.5 tonnes thrust and a specific impulse of 215 seconds was perfected. But all attempts to scale this engine up to the 25 tonnes thrust required for the A-4 met insurmountable combustion instability problems. Finally an interim solution to produce test A-4 missiles was found - clustering 18 of the 1.5 tonne combustion chambers, feeding into a common mixing chamber. In fact this immensely complex 'interim' design had to be pressed into production.
Development of the aerodynamics and control systems for the A-4 took hundreds of tests  in wind tunnels, air-drops, and powered flights. This was also a grueling trial and error process, for there was little theory and no practical experience in supersonic aerodynamics. A missile had to be controlled when rising vertically at near zero speed, where aerodynamic surfaces would be ineffective. Then it had to remain controllable and stable at subsonic, transonic, and supersonic speeds up to Mach 4. It was not until mid-1942, ten years after development had started, that the first test A-4 was launched. But at least it was shown that the long development process had produced workable aerodynamic and control solutions.
The turbopumps to feed the propellants to the engines proved relatively easy - to Wernher von Braun's surprise, high-volume low-weight pumps were already well developed for fire engines. The other structural elements were well within the allowable mass.

The final area of completely new technology was the guidance system. How could a missile with a range of 320 km be guided accurately to its target? It seemed only a radio beam guidance system could provide the necessary accuracy, but the A-4 developers had to take a backseat to development of such systems for the German bomber and interceptor forces. Therefore they settled for a control system that oriented the missile along a pre-determined path in a vertical plane pointed at the target. The system used accumulating accelerometers to determine when the missile had reached the correct velocity and then cut off the engine. It was thought that this would provide sufficient accuracy, although operations would indicate otherwise.
Hitler delayed the decision to put the A-4 into production for three years, from 1939 to 1942. However, given the difficulties in the development of the A-4, this seems doubtful. Even with the 1942 go-ahead, the A-4 was nowhere near a production design. Getting it into production concurrently with development was a nearly insurmountable problem - 65,000 changes were made to the initial production drawings. Tests of the first production missiles began in early 1944. Mysterious in-flight disintegrations of the missiles resulted in an 80% failure rate. These were found to have multiple causes, and the last of the several fixes to the missile was not introduced in the production line until November 1944.

German winged boost-glide Aggregat 4 (A-4b)
In early 1941 it was clear the final aerodynamic shape of the A-4 glider. It was refers A4-V12/c (later A-9). For testing a smaller scaled version was made. This construction was given the project-designation A-7. But even in the same year 1941, ended by order further testing on the A7/A9.
But in June 1944, the project could continue. In October 1944 suggested Wernher von Brown to build a new variant. There should be builded a "bastard" with parts of the A-4 and A-9, the A-4b. One of the beneficial changes is the replace the fuel container made of aluminum, with a container of "Mipolan" impregnated cotton. In this configuration was launched on Dec. 27, 1944 the first A-4b “Bastard”. The next A-4b "Bastard" was launched successful on Jan. 24, 1945. The difference between A-9 and A-4b is easily discernible on the control-wings. Contrary to the A-9 at the A-4b was used a standard A-4 tail with small additional control-wings.

U.S. experimental rocket A-4
Between April 16, 1946 and September 19, 1952 General Electric launched 63 rockets from the White Sands Proving Grounds. A rhesus monkey named Albert became the first animal to flyby in a rocket when he was launched in a USAF A-4 rocket in 1948.

U.S. geophysical rocket A-4 Bumper WAC

Six of the V2 launches were as the first stage of the Bumper rocket. The WAC Corporal was used as an upper stage on the V2, producing Americas first large multi-staged rocket. This combination was named Bumper, and reached an altitude of 405 kilometers on February 24, 1949.

The rocket WAC Corporal was to carry 11 kg of instrumentation to an altitude of at least 30 km. The WAC Corporal was boosted into the air by a Tiny Tim 11.75" solid-fueled rocket, and powered by a liquid-fueled sustainer engine. The nose cone was designed to separate near the end of the flight, releasing a parachute for instrument recovery.

In May 1948 that year the first Bumper was launched. It had only a dummy upper stage with a small solid-propellant charge to test stage separation, and did achieve its objectives. The first flight with a live Bumper WAC (the third one) occurred on 30 September 1948, but failed because the WAC's engine exploded on ignition. A design deficiency was tracked down and corrected, and (after a A-4 failure in November), the fifth Bumper flight on 24 February 1949 was the first full success. In that day, the upper stage reached an altitude of 393 km.

After a A-4 failure on the sixth flight, it was decided that the remaining two Bumpers would be used to fly the Bumper WAC as fast as possible to produce aerodynamic data at unprecedented speeds. On the first launch of an RV-A-4 at the new launch site  Cape Canaveral, the upper stage failed to ignite, but the second and final attempt on 29 July 1950 was successful and the Bumper WAC reached a speed of 5,260 km/h.

U.S. experimental A-4 Ramjet rocket

The Ramjet rocket consisted of a A-4, which had a ramjet-powered second stage (called "Ram") mounted semi-recessed on top. The "Ram" was a small vehicle with large wedge-shaped wings, which actually housed small rectangular-section ramjet units. The A-4 first stage had enlarged fins to improve stability of the whole missile. The rocket was launched into an arched trajectory, and after burnout of the A-4 engine, the "Ram" was to be separated from the A-4 by diffential aerodynamic drag. As soon as the "Ram" was no longer climbing, the ramjet units were to ignite and propel the vehicle to a speed of about 1000 m/s. The "Ram" was to carry a newly developed advanced gyro-inertial stabilization and guidance system. The first flight of a A-4 Ramjet occurred in May 1947, and used only a mockup "Ram" with dummy (non-burning) ramjets to measure dynamic pressures in the ramjet ducts. Although the flight was unsuccessful. The three remaining flights eventually occurred in January 1949, October 1949 and November 1950, but it is unclear whether the three latter flights carried a "Ram" with live ramjets and/or released the "Ram" into free flight.
 
Soviet experimental rocket R-1A

To mature mass and operating characteristics of rocket R-1, its designers proposed to use an integral fuel tank and a warhead separated from the rocket at the ascent phase completion. In this case, only the ascent phase appeared to be rated for the launch vehicle and considerably more favorable regarding mechanical and thermal loads as compared to the atmospheric portion of the descent phase of the flight trajectory. To verify experimentally those new ideas, mainly to investigate peculiar features of the warhead separation process at the ascent phase completion, rocket R-1A has been developed. However, since many organizations showed interest in using the new rocket for their purposes, the experiment program fell far beyond the original plan.
Rocket R-1A became the first rocket to carry science equipment in recoverable containers to upper atmospheric layers (the containers were located in a section of the rocket stabilizers). The solution to separate the warhead turned to be so good that it was employed in all subsequent domestic rockets. To measure physical parameters in the upper rarefied atmosphere, rocket R-1A was already provided with the instrumentation system conventionally named "FIAN-1".

 

Soviet geophysical rockets R-1B, R-1W, R-1D and R-1E

The first geophysical experiments have been accommodated. The obtained data served as a basis to work out a large geophysical research program pursuing interests of the Academy of Sciences of the USSR and designers of modified rocket R-1 intended for that purpose (R-1B, R-1V, R-1D, R-1E).
All four launches of rocket R-1B that took place in July - August 1951 were vertical with one launch failed. The rocket carried experimental animals accommodated in a special pressurized compartment to study their behavior in space environment. On July 1951 dogs Dezik and Tsygan were the first to successfully fly on rocket R-1B.
Rocket  R-1 W differed from R-1B only in that the FIAN-1 equipment was replaced by a parachute system to recover the rocket body. In total, two launches have been carried out in July - August 1951.
Unlike rockets R-1B and R-1V where experimental animals had to be returned in a pressurized compartment on a parachute, on rocket R-1D each of the two dogs was catapulted in a space suit mounted on a special cradle provided with a parachute system and a Life Support System. In addition, on rocket R-1D, instead of the FIAN-1 compartment, science hardware was accommodated to study vertical distribution of ionization density in ionosphere and propagation of super long waves in atmosphere and space. All three launches of rocket R-1D that took place in June-August 1951 were successful.
Through launches of rocket R-1E one more attempt has been made to solve the rocket body recovery problem. For this purpose, three powder boosters were provided on the warhead to impart a separation velocity of about 12 m/s to it. However, this was not sufficient enough. A new constructive option of the rocket body return system implied the use of a pyro gun that had not only to activate pilot chutes, but also simultaneously release parachute packages containing main cupolas. Totally, from January 1955 to April 1956, six launches have been carried out of which four were successful.