Today there are exactly two weeks left of Summer of Code!
Recent improvements: Completely rewritten servlets. I now interact correctly (I think) with the complex obs API, instead of using the getComplexDataFile shortcut. I've created a few new classes:
- AnnotatedImageHandler, which overrides the normal ImageHandler
- AnnotatedImage, which represents a Java BufferedImage with annotations and other metadata
- ImageAnnotation, which represents one annotation for an AnnotatedImage.
I've also added a buffer that stores recently used complex obs including their complex data. The buffer is circular, so new content overwrites old content, and the buffer size is configurable through a global property. As a result I've solved the performance problem with big image files. Even my largest test image, at 109 RGB megapixels, (328 MB when decoded) now loads pretty fast.
German superweapons
In the fourth article in my series about WWII technology you never heard of in school, I'll discuss the German superweapons, the Vergeltungswaffen.
Germany originally intended to invade Great Britain in September 1940, as part of Operation Sealion. Before that could happen though, they needed to gain air superiority - i.e. to destroy the British air force, the RAF. Even though the German Luftwaffe had more and better aircraft, an unprecedented effort by the RAF managed to decide the Battle of Britain in favor of the British.
As the Germans gave up, Hitler instead turned to the Vergeltungswaffen (retaliatory weapons) in order to pummel the British into submission by an exceedingly expensive bombardment of London's civilian population. These weapons contained some of the most advanced technology of the war.
Three projects were developed in parallel, but only the V-1 and the V-2 were used successfully. While these two have become quite famous, the V-3 has been almost forgotten.
V-1 flying bomb
Nicknamed the buzz bomb for it characteristic noise, the V-1 was one of the first guided missiles. Essentially an unmanned aircraft, powered by one of the first jet engines ever devised, it was used relatively successfully. It was guided by a gyrocompass and reached speeds of 630 km/h. It was five meters long and was launched from a catapult.
The V-1 has perhaps been most accurately described by renowned military historian Zack Parsons as "a really crappy and inaccurate cruise missile that made a scary noise".
Approximately 10,000 were fired at England, but only 25% ever hit their targets, the rest being lost to countermeasures or due to failing guidance systems. Some of the fastest British fighters could just barely manage to catch up with a V-1 and topple it by slightly nudging its wing. This maneuver would tip the V-1's wing up and send the missile into an uncontrolled dive. The V-1 could also sometimes be destroyed by conventional anti-aircraft weapons.
V-2 rocket
The V-2 was was the first ballistic missile. It had a weight of 12.5 metric tons, achieved supersonic speeds and was powered by ethanol and liquid oxygen. The guidance system was a combination of accelerometer and gyroscopes. The V-2 project was decades ahead of any other country's rocket technology.
Although a much more devastating weapon than the V-1, because there were not yet any countermeasures that could be used against supersonic weapons, it was less effective because of its technical complexity and lower volume of production. Around 1400 rockets were fired at London.
The V-2 was the single most expensive German project during WWII, but had virtually no effect on the outcome of the war.
The scientists in charge of the V-2 program, led by Werner von Braun, were captured with their equipment by the Americans and the Soviets at the end of the war, and went on to design ICBMs and spacecraft. The V-2 is the grandfather of all modern rockets, including the Saturn V that sent the first men to the moon.
V-3 cannon
While the V-1 and V2 are very well known, the V-3 is not. Also known as Hochdruckpumpe (high-pressure pump) the V-3 was a revolutionary new artillery design. It consisted of a 140 meter long smooth-bored gun barrel, buried underground in France. Each installation had five of these guns, and all of the support facilities were in adjoining bunkers dug out by French slave laborers.
The most unique part of the V-3 design was the way that the projectile was propelled: The gun barrel had a series of chambers along the sides, filled with explosives. As the projectile moved upwards, each chamber fired in sequence providing additional acceleration. The projectile itself had stabilizing fins and was encased in a sabot when fired.
If successfully deployed the guns would have had a firing rate of one shot every five minute per gun, or one shot every minute for each five-gun battery. The maximum range would have been an impressive 165 km.
Allied intelligence was tipped off about the V-3 weapons by French resistance fighters while the guns were still under construction, in 1944. Frightened by a new weapon potentially more deadly than the V-1 and V-2, they began air raids using the bunker-busting Tallboy and Grand Slam bombs, which I discussed in a previous article in this series.
The raids proved ineffective though, and construction proceeded almost uninterrupted. While hugely powerful, the anti-bunker bombs were unguided and often missed. Even when they didn't, the bunker was thick enough to withstand the damage. The RAF turned to increasingly desperate methods, such as Project Aphrodite. In this maneuver, a two-manned crew flew a B-17 bomber crammed full of explosives towards the target. They were then supposed to bail out just in time, and a second bomber would then guide the first one in the rest of the way, using a crude TV-remote control system. This failed miserably, and Joseph Kennedy, president John F. Kennedy's brother, was killed in one of these raids.
As the allied invasion of France progressed though, it became clear that the guns would not be completed in time. They were abandoned and captured by the British, who in turn dynamited the facility in order to prevent the French from having a ready-made London gun. The British and French were allies of course, but you want to be on the safe side with stuff like the V-3.
