Rockets have nothing to do with submarines but they're exciting and dangerous - be they government sponsored or corporate.
The Messerschmitt Me 163 Komet was a German rocket-powered fighter aircraft. Test flown Hanna Reitsch and others. The Me 163 was the only operational rocket-powered fighter aircraft used. Although revolutionary and capable of performance unrivaled at the time, it proved ineffective as a fighter and resulted in the destruction of very few Allied aircraft.
The Me 163's explosive fuel (see above Youtube 2 minutes in) was also extremely toxic when touching organic material eg. the pilot (2:30)! When Germany was running out of experienced pilots the 163s also needed expert piloting to hit bombers at closing speeds of up to 900 mph for head-on attacks.
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Rockets revolutionised test piloting. The Youtube above depicts Cuck Yeager breaking the sound barrier in the film The Right Stuff. The Bell X-1 was built for speed, breaking the sound barrier just over 2 years after WWII. The mothership was a B-50 (with more powerful and reliable engines than a B-29). On the ground, no one had ever heard a sonic boom before. It rattled the photographs of the test pilots who had died and it was assumed that Yeager had exploded and there would be another funeral for another forgotten test pilot. It took a few moments for everyone to realize the sound barrier had finally been broken and the space age had arrived.
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Apollo 11 in 1969 needs no introduction.
After the White Knight Two - VSS Enterprise crash see Youtube on October 31, 2014 Virgin's Richard Branson may be turning to a safer project (with no passengers) (below).
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Branson is developing the 747 booster rocket combination "LauncherOne". The system is mainly designed to boost Low Earth Orbiting satellites but perhaps could carry payloads to space stations.
Pete