WWII: The V-1 Rocket, German Vengeance

On December 24, 1942, the first powered flight of V-1 'buzz bomb' occurred in Peenemunde, Germany. From the article:

"The V-1 flying bomb was developed by Germany during World War II (1939-1945) as a vengeance weapon and was an early unguided cruise missile. Tested at Peenemünde-West facility, the V-1 was the only production aircraft to utilize a pulsejet for its power plant. The first of the "V-weapons" to become operational, the V-1 flying bomb entered service in June 1944 and was used to strike London and southeastern England from launch facilities in northern France and the Low Countries. When these facilities were overrun, V-1s were fired at Allied port facilities around Antwerp, Belgium. Due to its high speed, few Allied fighters were capable of intercepting a V-1 in flight.

Fast Facts: V-1 Flying Bomb
•User: Nazi Germany
•Manufacturer: Fieseler
•Introduced: 1944
•Length: 27 ft., 3 in.
•Wingspan: 17 ft. 6 in.
•Loaded Weight: 4,750 lbs.

Performance
•Power Plant: Argus As 109-014 pulse jet engine
•Range: 150 miles
•Max Speed: 393 mph
•Guidance System: Gyrocompass based autopilot

Armament
•Warhead: 1,870 lbs. Amatol

Design
The idea of a flying bomb was first proposed to the Luftwaffe in 1939. Turned down, a second proposal was also declined in 1941. With German losses increasing, the Luftwaffe revisited the concept in June 1942 and approved the development of an inexpensive flying bomb that possessed a range of around 150 miles. To protect the project from Allied spies, it was designated "Flak Ziel Geraet" (anti-aircraft target apparatus). Design of the weapon was overseen by Robert Lusser of Fieseler and Fritz Gosslau of the Argus engine works.

Refining the earlier work of Paul Schmidt, Gosslau designed a pulse jet engine for the weapon. Consisting of few moving parts, the pulse jet operated by air entering into the intake where it was mixed with fuel and ignited by spark plugs. The combustion of the mixture forced sets of intake shutters closed, producing a burst of thrust out the exhaust. The shutters then opened again in the airflow to repeat the process. This occurred around fifty times a second and gave the engine its distinctive "buzz" sound. A further advantage of the pulse jet design was that it could operate on low-grade fuel.

V-1 cutaway
Cutaway drawing of V-1. US Air Force
Gosslau's engine was mounted above a simple fuselage which possessed short, stubby wings. Designed by Lusser, the airframe was originally constructed entirely of welded sheet steel. In production, plywood was substituted for constructing the wings. The flying bomb was directed to its target through the use of a simple guidance system that relied on gyroscopes for stability, a magnetic compass for heading, and a barometric altimeter for altitude control. A vane anemometer on the nose drove a counter which determined when the target area was reached and triggered a mechanism to cause the bomb to dive.

Development
Development of the flying bomb progressed at the Peenemünde, where the V-2 rocket was being tested. The first glide test of the weapon occurred in early December 1942, with the first powered flight on Christmas Eve. Work continued through the spring of 1943, and on May 26, Nazi officials decided to place the weapon into production. Designated the Fiesler Fi-103, it was more commonly referred to as V-1, for "Vergeltungswaffe Einz" (Vengeance Weapon 1). With this approval, work accelerated at Peenemünde while operational units were formed and launch sites constructed.

German V-1
A German crew prepares a V-1, 1944. Bundesarchiv, Bild 146-1975-117-26 / Lysiak / CC-BY-SA 3.0
While many of the V-1's early test flights had commenced from German aircraft, the weapon was intended to be launched from ground sites through the use of ramps fitted with steam or chemical catapults. These sites were quickly constructed in northern France in the Pas-de-Calais region. While many early sites were destroyed by Allied aircraft as part of Operation Crossbow before becoming operational, new, concealed locations were built to replace them. While V-1 production was spread across Germany, many were built by the forced labor of enslaved people at the notorious underground "Mittelwerk" plant near Nordhausen.

Operational History
The first V-1 attacks occurred on June 13, 1944, when around ten of the missiles were fired towards London. V-1 attacks began in earnest two days later, inaugurating the "flying bomb blitz." Due to the odd sound of the V-1's engine, the British public dubbed the new weapon the "buzz bomb" and "doodlebug." Like the V-2, the V-1 was unable to strike specific targets and was intended to be an area weapon that inspired terror in the British population. Those on the ground quickly learned that the end of a V-1's "buzz" signaled that it was diving to the ground.

Early Allied efforts to counter the new weapon were haphazard as fighter patrols often lacked aircraft that could catch the V-1 at its cruising altitude of 2,000-3,000 feet and anti-aircraft guns could not traverse quickly enough to hit it. To combat the threat, anti-aircraft guns were redeployed across southeastern England and over 2,000 barrage balloons were also deployed. The only aircraft suitable for defensive duties in mid-1944 was the new Hawker Tempest which was only available in limited numbers. This was soon joined by modified P-51 Mustangs and Spitfire Mark XIVs.

Spitfire "tipping" a V-1
Seen in silhouette, a Royal Air Force Supermarine Spitfire manoeuvres alongside a German V-1 flying bomb in an attempt to deflect it from its target. Public Domain
At night, the De Havilland Mosquito was used as an effective interceptor. While the Allies made improvements in aerial interception, new tools aided the fight from the ground. In addition to faster-traversing guns, the arrival of gun-laying radars (such as the SCR-584) and proximity fuses made ground fire the most effective way of defeating the V-1. By late August 1944, 70% of V-1s were destroyed by guns on the coast. While these home defense techniques were becoming effective, the threat was only ended when Allied troops overran German launch positions in France and the Low Countries.

With the loss of these launch sites, the Germans were forced to rely on air-launched V-1s for striking at Britain. These were fired from modified Heinkel He-111s flying over the North Sea. A total of 1,176 V-1s were launched in this manner until the Luftwaffe suspended the approach due to bomber losses in January 1945. Though no longer able to hit targets in Britain, the Germans continued to use the V-1 to strike at Antwerp and other key sites in the Low Countries that had been liberated by the Allies.

He 111 with V-1
A German Luftwaffe Heinkel He 111 H-22 with a V-1 mounted. US Air Force
Over 30,000 V-1s were produced during the war with around 10,000 fired at targets in Britain. Of these, only 2,419 reached London, killing 6,184 people and injuring 17,981. Antwerp, a popular target, was hit by 2,448 between October 1944 and March 1945. A total of around 9,000 were fired at targets in Continental Europe. Though V-1s only struck their target 25% of the time, they proved more economical than the Luftwaffe's bombing campaign of 1940/41. Regardless, the V-1 was largely a terror weapon and had little overall impact on the outcome of the war.

During the war, both the United States and the Soviet Union reverse-engineered the V-1 and produced their versions. Though neither saw combat service, the American JB-2 was intended for use during the proposed invasion of Japan. Retained by the US Air Force, the JB-2 was used as a test platform into the 1950s.

World War II: V-2 Rocket

V-2 Rocket taking off
V-2 Rocket during launch. US Air Force
Updated March 16, 2018
In the early 1930s, the German military began to seek out new weapons that would not violate the terms of the Treaty of Versailles. Assigned to aid in this cause, Captain Walter Dornberger, an artilleryman by trade, was ordered to investigate the feasibility of rockets. Contacting the Verein für Raumschiffahrt (German Rocket Society), he soon came in contact with a young engineer named Wernher von Braun. Impressed with his work, Dornberger recruited von Braun to aid in developing liquid-fueled rockets for the military in August 1932.

The eventual result would be the world's first guided ballistic missile, the V-2 rocket. Originally known as the A4, the V-2 featured a range of 200 miles and a maximum speed of 3,545 mph. Its 2,200 pounds of explosives and liquid propellant rocket engine allowed Hitler's army to employ it with deadly accuracy.

Design and Development
Commencing work with a team of 80 engineers at Kummersdorf, von Braun created the small A2 rocket in late 1934. While somewhat successful, the A2 relied on a primitive cooling system for its engine. Pressing on, von Braun's team moved to a larger facility at Peenemunde on the Baltic coast, the same facility that developed the V-1 flying bomb, and launched the first A3 three years later. Intended to be a smaller prototype of the A4 war rocket, the A3's engine nonetheless lacked endurance, and problems quickly emerged with its control systems and aerodynamics. Accepting that the A3 was a failure, the A4 was postponed while the problems were dealt with using the smaller A5.

The first major issue to be addressed was constructing an engine powerful enough to lift the A4. This became a seven-year development process that led to the invention of new fuel nozzles, a pre-chamber system for mixing oxidizer and propellant, a shorter combustion chamber, and a shorter exhaust nozzle. Next, designers were forced to create a guidance system for the rocket that would allow it to reach the proper velocity before shutting off the engines. The result of this research was the creation of an early inertial guidance system, which would allow the A4 to hit a city-sized target at a range of 200 miles.

As the A4 would be traveling at supersonic speeds, the team was forced to conduct repeated tests of possible shapes. While supersonic wind tunnels were built at Peenemunde, they were not completed in time to test the A4 before being put into service, and many of the aerodynamic tests were conducted on a trial and error basis with conclusions based on informed guesswork. A final issue was developing a radio transmission system that could relay information about the rocket's performance to controllers on the ground. Attacking the problem, the scientists at Peenemunde created one of the first telemetry systems to transmit data.

Production and a New Name
In the early days of World War II, Hitler was not particularly enthusiastic about the rocket program, believing that the weapon was simply a more expensive artillery shell with a longer range. Eventually, Hitler did warm to the program, and on December 22, 1942, authorized the A4 to be produced as a weapon. Though production was approved, thousands of changes were made to the final design before the first missiles were completed in early 1944. Initially, production of the A4, now re-designated the V-2, was slated for Peenemunde, Friedrichshafen, and Wiener Neustadt, as well as several smaller sites.

This was changed in late 1943 after Allied bombing raids against Peenemunde and other V-2 sites erroneously led the Germans to believe their production plans had been compromised. As a result, production shifted to underground facilities at Nordhausen (Mittelwerk) and Ebensee. The only plant to be fully operational by war's end, the Nordhausen factory utilized labor stolen from enslaved people from the nearby Mittelbau-Dora concentration camps. It is believed that around 20,000 prisoners died while working at the Nordhausen plant, a number that far exceeded the number of casualties inflicted by the weapon in combat. During the war, over 5,700 V-2s were built at various facilities.

Operational History
Originally, plans called for the V-2 to be launched from massive blockhouses located at Éperlecques and La Coupole near the English Channel. This static approach was soon scrapped in favor of mobile launchers. Traveling in convoys of 30 trucks, the V-2 team would arrive at the staging area where the warhead was installed and then tow it to the launch site on a trailer known as a Meillerwagen. There, the missile was placed on the launch platform, where it was armed, fueled, and the gyros set. This set-up took approximately 90 minutes, and the launch team could clear an area in 30 minutes after launch.

Thanks to this highly successful mobile system, up to 100 missiles a day could be launched by German V-2 forces. Also, due to their ability to stay on the move, V-2 convoys were rarely caught by Allied aircraft. The first V-2 attacks were launched against Paris and London on September 8, 1944. Over the next eight months, a total of 3,172 V-2 were launched at Allied cities, including London, Paris, Antwerp, Lille, Norwich, and Liege. Due to the missile's ballistic trajectory and extreme speed, which exceeded three times the speed of sound during descent, there was no existing and effective method for intercepting them. To combat the threat, several experiments using radio jamming (the British erroneously thought the rockets were radio-controlled) and anti-aircraft guns were conducted. These ultimately proved fruitless.

V-2 attacks against English and French targets only decreased when Allied troops were able to push back Germans forces and place these cities out of range. The last V-2-related casualties in Britain occurred on March 27, 1945. Accurately placed V-2s could cause extensive damage and over 2,500 were killed and nearly 6,000 wounded by the missile. Despite these casualties, the rocket's lack of a proximity fuse reduced losses as it frequently buried itself in the target area before detonating, which limited the effectiveness of the blast. Unrealized plans for the weapon included the development of a submarine-based variant as well as the construction of the rocket by the Japanese.

Postwar
Highly interested in the weapon, both American and Soviet forces scrambled to capture existing V-2 rockets and parts at the end of the war. In the conflict's final days, 126 scientists who had worked on the rocket, including von Braun and Dornberger, surrendered to American troops and assisted in further testing the missile before coming to the United States. While American V-2s were tested at the White Sands Missile Range in New Mexico, Soviet V-2s were taken to Kapustin Yar, a Russian rocket launch and development site two hours east of Volgograd. In 1947, an experiment called Operation Sandy was conducted by the U.S. Navy, which saw the successful launch of a V-2 from the deck of the USS Midway (CV-41). Working to develop more advanced rockets, von Braun's team at White Sands used variants of the V-2 up until 1952. The world's first successful large, liquid-fueled rocket, the V-2 broke new ground and was the basis for the rockets later used in the American and Soviet space programs."