Waterfall (rocket)
Wasserfall was the name of a German liquid missile that was developed as an anti-aircraft missile from 1943. Around 40 test flights took place from 1944 onwards. The missile was intended to support anti-aircraft batteries against high-flying bombers up to a distance of 30 miles. After the war, it was one of the foundations for the development of the first American and Soviet anti-aircraft missiles.
background
As early as the end of 1942, the Allied air superiority began to emerge. Many German pilots were killed or captured in the Battle of Britain . The single-engine Bf 109 and Fw 190 fighters in particular were not very effective against the four-engine bombers flying in at great heights , as their aircraft engines were not sufficiently powerful above full pressure altitude . This is why the development offices talked about the "piston engine crisis". The engines were highly developed further developments that only worked reliably for around 50 hours , especially when operated with processes for short-term performance enhancement such as the injection of nitrous oxide ( GM-1 ) or a methanol- water mixture ( MW-50 ). The need for high-quality steel, which was one of the scarce resources, could not be met in the course of the war. In addition, there was not enough high-octane aviation fuel , which is necessary for powerful engines.
The aim of air defense is to avert damage to the target to be defended. This can be done by rendering the attacker harmless or forcing them to evade, thus reducing the hit rate. Dodging to greater altitudes means a reduction in the bomb load and a decrease in the probability of being hit. The aspects mentioned made a remotely controlled or computer-controlled guided missile an obvious and realistic solution to the problem. In the German Reich, corresponding successes had already been achieved in the development of V weapons , torpedoes and rocket engines in order to be able to realize a rocket.
The development of the waterfall rocket, as well as the other anti-aircraft rocket projects ( butterfly , gentian - both winged projects for the subsonic range - and Rhine daughter ) was carried out as part of the Vesuvius program . The corresponding projects were started a total of twelve times between 1940 and 1945 and then canceled.
conditions
- The missile must be fired at high speed at a bomber formation. A high speed with a mainly vertical start leads to a high target height and poor controllability.
- Since a direct hit is relatively unlikely, a fragmentation bomb with a sufficient explosion radius must be detonated in the warhead and damage as many enemy aircraft as possible with shrapnel .
- For this, the missile must have a predictable average speed; without this, a pre-calculation of the lead point is not possible.
- The avionics must keep the rocket on the straightest possible flight path.
- An autopilot must safely suppress the roll of the rocket.
- The rocket must be able to stand on its mount ready for launch for several weeks so that it can then be fired in the event of an attack.
- As few technical and military personnel as possible may be tied up for use, as the missile may stand around unused for weeks.
- A minimal advance warning time must be sufficient to put the missile, fire control system and launch device on standby.
- It is of no small relevance that the rocket can be manufactured in sections, some of which can be carried out by small craft businesses with sufficient precision, without the respective business having to know how the individual components are used in order to make espionage more difficult ( Need-to-know principle ).
realization
drive
Excluded from the outset that had Walter drives (z. B. Walter HWK 109-509 of the Me 163 ), solid engines and with liquid oxygen working liquid rocket engines , as these were not suitable for a ready resting on a gun carriage rocket. The two components of the Walter drive ( T-material with 80% hydrogen peroxide and C-material with, among other things, 30% hydrazine hydrate ) were extremely critical in their handling and therefore difficult to refuel. In addition, hydrogen peroxide in particular decomposed very quickly all systems known up to that point. Stainless steels, on the other hand, were too resource-critical for a “disposable weapon”. Solid rockets show a change in their burning behavior after long storage. If the propellant condenses, it burns too quickly and the rising pressure in the combustion chamber explodes the rocket in flight. The liquid oxygen used in the V2 rocket is difficult to handle because it evaporates quickly and forms explosive mixtures. In addition, it was practically impossible to refuel a rocket with the fuel ethanol under combat conditions - for example when a swarm of bombers was approaching - as this had to be re-tempered after refueling. In order to be able to pump out the fuel again in the event of the all-clear, a separate device and a tank ventilation on the rocket would have been necessary. However, even with such devices, pumping out and refueling would have been difficult to carry out.
At the waterfall it was decided to use a hypergolic two-component liquid fuel. A small compressed air bottle should supply the tanks with positive pressure when starting. Tank pendulums were unnecessary, as the rocket should neither roll (like the Katyusha ) nor transition into level flight and would therefore always remain in the positive G range. A mixture of Visol and SV substances was chosen as the fuel . SV substance (10% sulfuric acid + 90% nitric acid ) was widespread in the explosives industry and available in sufficient quantities, Visol ( isobutyl vinyl ether + aniline ) was also available as a by-product from fuel distillation (coal liquefaction). The thrust to be achieved with it was completely sufficient to meet the requirements.
Construction
Like current missiles (e.g. the Sidewinder ), the waterfall was constructed as a sectional construction. The production of the tank section could be carried out in craft workshops. The warhead corresponded to a then current air mine ; only the rocket motor and the flight computer were critical of espionage. In order to simplify the assembly, no cable harnesses or cables should be necessary. This was only possible because each section of the weapon had an absolute task priority:
- The tank section contained the two fuel tanks and the pressurized gas cylinder that built up the fuel pressure in the tank itself. A fuel pump was not necessary and therefore did not represent a source of error. The tank section should be screwed to the drive section before being transported to the place of use (because the tanks had to be connected to the engine in an absolutely tight manner).
- The drive section contained the rocket motor. The thrust was regulated by a simple gravitational balance via fuel valves (weight on spring). Thus the top speed of the waterfall was self-regulated. The engine was designed so generously stable that a combustion chamber pressure control was unnecessary. The rocket motor was built according to the regenerative cooling principle. The tail fins had a simple, self-steering property: the large tail surfaces were deflected by the impact of the airstream and protruded so far into the jet of the engine that they immediately countered. This enabled the rocket to achieve a fixed acceleration with minimal effort and at least fly roughly in a straight line. A build-up of the individual regulations against each other was reliably prevented by the fact that only a few manipulated variables and regulatory inertia, insofar as they were not already inherent in the system, were inserted.
- The control section contained a simple course calculator , as it was used thousands of times in torpedoes and was therefore available: a gyro prevented the rocket from rolling, another kept it vertical (or at the pre-calculated approach angle). A mechanical computer averaged the target and actual angles against each other. It was also planned to introduce an infrared seeker head for use at night. These values could have been fed into the mechanical target / actual computer analogous to the normal flight angle control. The flight course was controlled by the four front wings by means of servo motors.
- The warhead was a combination of an air mine and frag grenade; he received a radio receiver to detonate remotely when approaching the target, or a time fuse to destroy himself if the regular ignition mechanisms fail (use over inhabited areas / counter-espionage). Magnetic proximity fuses, infrared sensors and acoustic search heads (analogue self-searching torpedo " Wren ") were also being tested.
This sharp separation of tasks was intended to ensure that the waterfall could be installed quickly, easily and without errors on site. The dismantling facilitated the transport as well as the storage in air raid shelters and the assembly without crane or lifting device etc.
The sectional construction offered the weapon good further development options, because as long as the center of gravity and total mass remained the same, each individual section could be further improved independently of the others in terms of its economic efficiency in production and use as well as in terms of increased combat value . Personnel, technical equipment, test set-ups for coordinating the individual components with one another should be unnecessary and at the same time the flight characteristics should always be constant and predictable.
Starting sequence
The waterfall was designed to be maintenance-free and ready to go on the mount for weeks if required. Before taking off, it only had to be freed from the camouflage and activated. For this purpose, like a torpedo, the gyroscopes were first started and calibrated to zero. The tanks were then pressurized (first the Visol, then the SV) and the tightness checked. Since the rocket was always launched vertically, the target approach angle had to be programmed in the course computer. Precise knowledge of the position and direction of flight of the targeted bombers was also important. However, these were reconnaissance data that were no longer completely available after the Allies landed in Normandy, which impaired the entire bomber defense. If the bomber and the predicted target vector overlap, the warhead was unlocked and the weapon fired. When approaching the target, the missile detected a change in the magnetic field and detonated the warhead.
Development history
The rocket was tested in the "Peenemünde-West" air force test site under the leadership of Walter Thiel . The first model tests from March 1943 were very promising. Thiel's death in the attack by the British Air Force ( Operation Hydra ) on the Army Research Center and the testing site in mid-August 1943 set the project back months. The first launch on January 8, 1944 failed. The rocket did not break the sound barrier and so only reached a summit height of about 7000 m. This missile and control malfunction was foreseen; as a result, new ideas flowed into the next prototype. The first successful launch took place on February 29, 1944. The rocket reached a speed of 2772 km / h in a vertical position and at 20 km the fuel was exhausted.
By the end of the war, 50 prototypes were built with which flight and, above all, control studies were carried out. 40 trial starts are documented. At the end of February 1945, production was stopped in favor of the V2 rocket .
After the war
With Operation Unicorn (company Einhorn) the USA succeeded in stealing the plans and models and engaging German scientists as part of Operation Paperclip . After the war, copies of the waterfall rocket under the designation Hermes-A1 were tested in the United States for trial purposes . The Soviet Union began the reconstruction in the Berlin Institute and then continued after the Ossawakim campaign with prototypes of the R-101 and R-108 in Podlipki and Gorodomlija .
Technical specifications
- First launch: April 29, 1944
- Length: 7.85 m
- Diameter (with wings): 2.51 m
- Fuel: 450 kg Visol + 1500 kg SV material
- Payload / warhead: up to 300 kg
- Total mass: 3500 kg
- Thrust: 8000 kp
- Burn time: max. 42 p
- Board battery: 2 boxes AFA 3 T 50/80 with 25 V.
- Maximum speed (v max ): 400-800 m / s
- Summit height: 18,000 m or 24,000 m (?)
- Cross range: 26,000 m
- Particularities:
rating
The rocket marked the development of the following decades, with the rockets serving to defend against high-flying strategic bomber formations and barrel weapons such as Schilka (ZSU-23-4) or the Gepard anti-aircraft gun to protect objects against low-flying planes or helicopters.
A comparison with the V2 of the V weapons program does not make sense. Both were created in Peenemünde as German rockets in World War II . However, they were developed by completely independent working groups, had different objectives and used different technical principles (drives, fuels, course calculators, etc.). However, V-Waffen production was preferred by Hitler and Speer in terms of resource calculation, personnel (and also the allocation of forced laborers) as well as other framework conditions.
After the war, waterfall technology was incorporated into the development of several nations:
- France: Eole (rocket) and later Edelstein program
- USA: Hermes A-1 and later Viking
- Egypt: Al Kaher (rocket)
- Soviet Union: R101 (missile) and later Scud systems with R-11 and R-17
French EOLE
American Hermes A-1
american viking
Egyptian Al-Kaher-1
soviet missiles
See also
- Gentian (rocket)
- Fire lily (anti-aircraft missile)
- Fritz X
- Typhoon (anti-aircraft missile)
- Rheinbote (rocket)
- Rhine daughter (rocket)
- Ruhrstahl X-4
- Henschel Hs 117
- Henschel Hs 293
literature
- Joachim Engelmann: Secret armory Peenemünde. V2 - waterfall - butterfly. Edition Dörfler in Nebel-Verlag, Eggolsheim 2006, ISBN 3-89555-370-0 ( Dörfler Zeitgeschichte ).
- Fritz Hahn: Weapons and Secret Weapons of the German Army 1933–1945. 3rd edition, special edition in one volume, Bernard & Graefe, Bonn 1998, ISBN 3-7637-5915-8 .
- Ernst Klee , Otto Merk: Back then in Peenemünde. At the birthplace of space travel. Gerhard Stalling Verlag, Oldenburg et al. 1985, ISBN 3-7979-1318-4 .
- Rudolf Lusar: The German weapons and secret weapons of the 2nd world war and their further development. 6th heavily revised and expanded edition, Lehmanns-Verlag, Munich 1971, ISBN 3-469-00296-7 .
- Heinz J. Nowarra : The German Air Armament 1933-1945. Volume 4: Aircraft types MIAG - Zeppelin, missiles, aircraft engines, on-board weapons, drop weapons, radios, other air force equipment, anti-aircraft artillery. Bernard & Graefe, Koblenz 1993, ISBN 3-7637-5468-7 .
- OP 1666: German explosive Ordnance. Volume 1. Navy Department - Bureau of Ordnance, Washington DC 1946, the drawing is also taken from this work.
Web links
- EMW C2 'waterfall' on luftarchiv.de
- Waterfall in the Encyclopedia Astronautica (English)
Individual evidence
- ↑ Boelcke, German Armament, 1969, p. 340.
- ↑ Hermes A-1. In: Astronautix. Retrieved April 27, 2020 (English).
- ↑ Waterfall. In: Astronautix. Retrieved April 27, 2020 (English).
- ↑ Norbert Brügge: The history of post-war rockets on base German WW-II "Wasserfall" missile propulsion (English) (accessed October 7, 2019)