Aggregat

The Aggregate series was a set of rocket designs developed in 1933–1945 by a research program of Nazi Germany's army. Its greatest success was the A4, more commonly known as the V-2.

Variations

Aggregate rockets compared

A1

The A1 was the first rocket design in the Aggregate series. It was designed in 1933 by Wernher von Braun in a Wehrmacht (German armed forces) research program at Kummersdorf headed by Walter Dornberger. The A-1 was the grandfather of most modern rockets. The rocket was 1.4 metres (4 ft 7 in) long, 30.5 centimetres (12 in) in diameter, and had a takeoff weight of 150 kilograms (331 lb). The engine, designed by Arthur Rudolph, used a pressure-fed propellant system burning alcohol and liquid oxygen, and produced 300 kgf (660 lbf, 2.9 kN) of thrust for 16 seconds. The rocket was stabilized by a 90 pound gyroscope in the nose, but there was concern that this might cause problems with the liquid fuels. Although the engine had been successfully test fired, the first flight attempt blew up on the launching pad. Since the design was thought to be unstable, no further attempts were made, and efforts moved to the A2 design (Gatland 1989, p. 10).

A2

A-2 Rocket

The A2 was designed in 1934 by von Braun under the program at Kummersdorf headed by Walter Dornberger.

At a length of 1.6 metres (5 ft 3 in) and thrust of 3 kN from alcohol and liquid oxygen, it was in outline similar to the A1. However, in contrast to the A1, the A2 had the stabilization gyroscopes in the center of the rocket between the alcohol and oxygen tanks, which made it more stable. The rocket weighed 72 kilograms (159 lb) empty, with takeoff weight of 107 kilograms (236 lb). Initial flight testing was done in September 1934 at Kummersdorf.

Two A2s were built for a full out test, and were named after a Wilhelm Busch cartoon, Max and Moritz. On December 19 and December 20, 1934 they were launched in front of the Army brass on Borkum island in the North Sea. They reached altitudes of 2.2 kilometres (1.4 mi) and 3.5 kilometres (2.2 mi).

A3

The A3 was first launched on December 4, 1937, and was intended to test components for the planned A4.

Only three more test launches were carried out, all of them failures. The final launch, on December 11, 1937, was typical of all the attempts: the engine cut out early, and the rocket was destroyed as it fell to the ground, the parachute failing to deploy. All the failures were due to the unstable design of the rocket's experimental inertial guidance system.

After this last unsuccessful launch, the A3 was abandoned, and a complete redesign was carried out to bring the A5 into being, and to continue subscale testing for the A4.

The A3 was the first Peenemünde design (Huzel 1962, p. 235). In 1936, Army General von Fritsch witnessed a static firing of an A3 at Kummersdorf, and was sufficiently impressed to lend his support to the rocket program (Huzel 1962, p. 233). Since ground was not broken until August, 1936, von Fritsch's viewing must have been in September through December. The A3 also used a pressure-fed propellant system, using the same liquid oxygen and 75% alcohol mixture as the A1 and A2. It generated 3,300 pounds of thrust (14.7 kN) for 45 seconds. It used a three-gyroscope system to deflect tungsten-alloy jet vanes (Huzel 1962, p. 236). Several A3s were launched, reaching a maximum downrange of 7.5 miles (12.1 km) and maximum altitude of 11 miles (18 km). Three A3s were launched from Greifswalder Oie in Autumn 1937. They carried a three-axis gyro control system which actuated exhaust vanes. On the first launch, the parachute opened after five seconds, causing the rocket to crash into the sea. Parachutes were omitted on the second and third launches, but both rockets still went out of control.

Specifications

Length: 6.74 meters (22.1 ft)

Diameter: 0.68 meters (2.2 ft)

Finspan: 0.93 meters (3.1 ft)

Launch mass: 748 kilograms (1650 lb)

Fuel: ethanol and liquid oxygen.

Liftoff thrust: 14.7 kN (1500 kgf).

A4 (V-2 rocket)

Main article: V-2

The A4 was a full-sized design with a range of about 175 kilometers (109 mi), a top altitude of 80 kilometers (50 mi) and a payload of about a tonne. Versions of the A4 included the first ballistic missile, the first projectile to reach space, and were actively used in warfare.

This increase in capability had come through a complete redesign of the A3 engine by Walter Thiel, known as the A5. It became clearer that von Braun's designs were turning into real weapons, and Dornberger moved the team from the artillery testing grounds at Kummersdorf (near Berlin) to a small town, Peenemünde, on the island of Usedom on Germany's Baltic coast, in order to provide more room for testing and greater secrecy. This version was completely reliable, and by 1941 the team had fired about 70 A5 rockets. The first A4 flew in March 1942, flying about 1.6 kilometers (1 mi) and crashing into the water. The second launch reached an altitude of 11 kilometers (7 mi) before exploding. The third rocket, launched on October 3, 1942, followed its trajectory perfectly. It landed 193 kilometers (120 mi) away, and reached a height of 80 kilometers (50 mi).

Production started in 1943 on the rocket, now known as the Vergeltungswaffe 2 (Vengeance Weapon 2) or V-2, at the insistence of Goebbels' propaganda ministry. The Allies were already aware of the weapon — at a test site at Blizna in Poland a fired missile had been recovered by Polish resistance agents from the banks of the Western Bug, and vital technical details had been given to British intelligence during Operation Most III.

A4-SLBM

Under Projekt Amerika Nazi Germany tried to develop the first submarine-launched ballistic missiles (SLBMs) to bomb New York and other American cities and objects. The tests of SLBM-variant of A4 rocket was fulfilled from U-boats submarine towed launch platforms.

These submersible, towed launch platforms were known as Lafferenz capsules. One 300 ton prototype capsule was built in Sichau Dockyards at Elbing. This capsule was tested in the Baltic with U-boat towing trials behind U-1053. U-1053 disappeared in trials off Bergen in February 1945. The submarine was found in March 2010.

Three 500 ton capsules under construction at the Vulcan yards in Stettin were captured by the Soviets. The 330t prototype Lafferenz Capsule used by U-1053 was never accounted for at the end of the war.

A4b

In the event that launch sites might be forced back into the Reich itself, von Braun and his colleagues were put under pressure to develop a longer-range version of the A-4 known alternately as A-9 and A-4b, the reason for the dual designation being that the A-4 series had received "national priority"; the A-4b designation ensured the availability of scarce resources.

In June 1939, Kurt Patt of the Peenemünde Design Office, proposed wings for converting rocket speed and altitude into aerodynamic lift and range. He also proposed the Flossengeschoss (fin projectile). Both concepts were utilized by Walter Dornberger when he drafted a memo for presentation to Hitler regarding the "America rocket" on July 31, 1940. It was calculated that by fitting wings, the rocket's range would be extended to 750 km (470 mi), allowing targets in Britain to be attacked from launch sites within Germany itself. It was intended that following launch the curve of the A-4b's trajectory would become shallower and the rocket would glide toward its target. It was anticipated that interception by enemy aircraft at the end of the glide phase would be virtually impossible as over the target the A-4b was intended to enter a near vertical dive leaving little time for interception.

The A-4b concept was tested by fitting swept back wings to two A-4s launched from Blizna. However, little development work had been carried out and the first launch on 27 December 1944 was a complete failure. The second launch attempt, on 24 January 1945, was partially successful, in that the wing broke off, but the A-4b still managed to become the first winged guided missile to break the sound barrier and attain Mach 4.

A5

The A5 was a scaled-down test model of the A4 which replaced the former unsuccessful A3 in this role. It was flown from 1938 to 1942, and played a vital role in testing the aerodynamics and technology of the A4. It had the same rocket engine as the A3, but had a new control system plus its shape more closely resembled that of the A4. 25 were launched, some several times; it was fitted with a parachute recovery system, plus it could float for up to two hours before sinking, so allowing recovery by boat. Variants were constructed both with no propulsion system and monopropellant engines for air drop testing.

The A5 was 5.825 m (19.11 ft) long, with a diameter of 0.78 m (2 ft 7 in) and a takeoff weight of 900 kg (2,000 lb), and like the A3 was fueled with alcohol with liquid oxygen as an oxidant. The first launch of the A5 took place in the summer of 1938 at Greifswalder Oie and the first successful guided flights were made in October 1939 in order to test the control systems planned for use in the A4. The A5 reached a ceiling of up to 12 km (7.5 mi).

A6

A6 was a designation applied to a variant of the A5 test rocket which used different propellants.

Some sources indicate that it was also applied to a speculative proposal for a manned reconnaissance version of the A4b winged variant of the A4. This A6 was initially proposed to the German Air Ministry as an uninterceptable reconnaissance craft. It would be launched vertically by rocket, taking it to an apogee of 95 km (59 mi); after re-entering the atmosphere it would enter a supersonic glide phase, when its single ramjet would be ignited. It was hoped that this would provide 15 to 20 minutes of cruise at 2,900 km/h (1,800 mph) and would allow the aircraft to return to its base and make a conventional runway landing assisted by a drag chute. However, the Air Ministry had no requirement for such an aircraft and the proposal was rejected. Similar concepts (though umnanned) were produced after the war in the form of the USA's SM-64 Navaho missile and the USSR's Burya, both intercontinental cruise missiles with ramjet propulsion.

A7

The A7 was a winged design that was never fully constructed. It was worked on between 1940 and 1943 at Peenemünde for the Kriegsmarine. The A7 was similar in structure to the A5, but had larger tail unit fins (1.621 m²) in order to obtain greater range in gliding flight. Two unpowered models of the A7 were dropped from airplanes in order to test flight stability; no powered test was ever performed. The finished rocket should have produced a takeoff thrust of 15 kN and a takeoff weight of 1000 kg. The design had a diameter of 0.38 m and a length of 5.91 m.

A8

The A8 was a proposed "stretched" variant of the A4, to use storable propellants (most likely nitric acid & kerosene). The design never reached the prototype stage, but further design work was carried out after the war by a German rocket team in France as the "Super V-2". The project was eventually cancelled, but led to the French Veronique and Diamant rocket projects.

A9

Aggregat-9
Type	IRBM second stage
Service history
In service	test only, not deployed
Production history
Manufacturer	studied by Army Research Center Peenemünde
Unit cost	none mass-manufactured
Specifications
Mass	16,259 kg
Length	14.18 m
Diameter	1.65 m maximum
Wingspan	3.2 m
Warhead	2,200 pound payload
Engine	A9
Operational range	500 statute miles
Flight altitude	190 km (in single flight) or 390 km (in A9/A10)
Maximum speed	3,400 m/s (in A9/A10)
Launch platform	ground launch pad or A-10

Under Projekt Amerika (besides the SLBM and long-range Amerika Bomber airplanes) Nazi Germany also tried to develop and probably to use the first intermediate-range ballistic missile (IRBM) A9/A10 rocket to bomb New York City and other American cities and targets in the north-eastern United States. Work on two-staged 100-ton 41-meter long A9/A10 "Amerikarakete" was started on summer 1940, then postponed on October 1942 and again resumed on September 1944. Test Stand VII launch pad was built at Peenemünde to test the A9 and A9/A10. To keep range to its target (New York City etc.) to a minimum and to increase the bomb payload to a maximum, it was intended to launch the A9/A10 from western Spain or France (this is shortest distance on the great circle) in its original form. The planned range of IRBM A9/A10 rocket was of 4100–5000 km, and a total flight time of 35 minutes. The IRBM A9/A10 rocket was intended to be guided primarily by radio and secondary by pilot (following the failure in November 1944 of the Elster operation, a Nazi plan to install a radio beacon on top of Empire State Building skyscraper).

The A9, second (upper) stage of IRBM A9/A10 rocket, was a further development of the A4 rocket (as the prototype for the A9 was the A4b). It was able to execute separate start and flight also.

According to some sources, a few test launches of A9 were in January, February and March 1945. It is known the official report to Berlin of von Braun in January 1945 that "the problem of the second stage is solved".

A10

The A10, which was probably never constructed, was intended to serve as first (lower) stage for the A9, to help it to reach an intercontinental range. Test Stand VII at Peenemünde was constructed as able to test A10.

The A10 was designed to have a diameter of 4.12 meters and to significantly exceed the A9 in its size. It was to be fueled with alcohol and liquid oxygen. The thrust of the engines would have been 235,000 kgf (2300 kN) with a 55 second burn time.

Different concepts for the A10's engine were studied. In one, a single very large combustion chamber and exit nozzle were used; in the other, six standard A4 (V-2) engines were to exhaust into a single combustion chamber and their mixed exhaust was to exit through a single nozzle.

Another concept included five smaller engine nozzles at the base of the A10

The A10 was intended to be recoverable for re-use and would have descended into the Atlantic under a large parachute after the upper stage A9 had separated from it.

A11

The A11, along with the A10 and A9, had the potential of launching a satellite payload. However, the conclusion of the war halted further efforts to develop or deploy this weapon.

It had a takeoff weight of 500 metric tons, a thrust of 11.8 meganewtons (MN) / 1,200,000 kgf or thrust (vacuum) 14 MN / 1,400,000 kgf, a diameter of 8.10 m, a span of 16.50 m and a length of 25.00 m.

A12

The A12 would have been a space transporter, capable of bringing up to 10 metric tons into low Earth orbit. The A12 was never constructed.

It is estimated that the A12 would have had a takeoff weight of 3,500 metric tons, a thrust of 100 MN / 10,000,000 kgf, a diameter of 11 m, a span of 23 m and a length of 33 m. The A12 was similar in design to the initial designs of the Saturn rockets.

References

• Dornberger, Walter (1981). Peenemünde : die Geschichte der V-Waffen / Walter Dornberger ; mit einem Geleitwort won Eberhard Rees. -- (in German). Germany: Bechtle. p. 313. ISBN 3762804044. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Huzel, Dieter K. (1981(Reprint)). Peenemünde to Canaveral. Greenwood Press (Reprint). p. 313. ISBN 0313229287. {{cite book}}: Check date values in: |date= (help); Cite has empty unknown parameter: |coauthors= (help)
• Neufeld, Michael (1996). The Rocket and the Reich: Peenemünde and the Coming of the Ballistic Missile Era. Cambridge, Massachusetts: Harvard University Press. ISBN 067477650X. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)

Further reading

• Encyclopedia Astronautica: A1, A2, A3, A5, A7, A8, A9, A10, A11, A9/A10/A11/A12
• V2 EMW A4b die bemannte Rakete
• http://www.aggregat-2.de/neubau.html - a site about the A2 (in German)
• The A4 Rocket (in German)
• Aerospace museum
• University of Oregon
• A8 statistics