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I read somewhere that only 2/3 of the V2 rockets reached their target - but how good was their precision when they reached the target? ±100 m? ±1 km? ±10 km?

d-b
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    While I think this is probably a good place to get an answer, maybe you should edit the question a little to make it clearer how this relates to space exploration. – Rikki-Tikki-Tavi Mar 12 '15 at 15:45
  • This question should be migrated to [History.SE]. – gerrit Mar 12 '15 at 16:11
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    I'm voting to close this question as off-topic because it is about history of warfare and not about space exploration. V2 rockets were not shot at London for the purpose to explore space. – gerrit Mar 12 '15 at 16:12
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    @gerrit - May we agree to disagree. V2 was the first rocket to reach space, precise MECO timing is still a valid concern for space launch systems today, and explosions/mishaps at reentry plagued A-4 and its derivatives for a long time. – Deer Hunter Mar 12 '15 at 19:08
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    In my humble opinion, this is on-topic. The V2 is the ancestor of all of our rockets, and its guidance and precision are relevant to the evolution of rockets for space exploration. Note that the Redstone (used for Mercury), the Atlas (used for Mercury and many missions), and the Titan (used for Gemini and other robotic missions such as Viking and Voyager) were all weapon systems as well. – Mark Adler Mar 12 '15 at 20:36
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    @gerrit commercial satellites aren't launched for the purpose of space exploration, but we still talk about them and their launch vehicles. On the other hand, the details of the impact don't seem to have much to do with spaceflight at all, although the details of the launch might. – raptortech97 Mar 12 '15 at 22:23
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    Rocketry in general has been considered on topic. I say this is on topic here, and a reasonable question. – PearsonArtPhoto Mar 12 '15 at 22:59
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    But is the precision of hitting a target a rocketry question? – gerrit Mar 13 '15 at 04:09
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    @gerrit - absolutely. You want precise orbit insertion and reentry. – Deer Hunter Mar 13 '15 at 04:26
  • I thought about placing it under History but since it was mostly a technical matter rather than a historical matter (Such as, e.g., "Did the V2 have any effect on the outcome of the war?") I decided to put it here. – d-b Mar 13 '15 at 16:23
  • If this is closed, migration to HSM would be appreciated. Of course, there are already good answers here, so l'd be fine with leaving it as is. – HDE 226868 Mar 20 '15 at 23:28

2 Answers2

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From Astronautix: "Tests of prototype V-2's in 1943 indicated a 4.5 km CEP (circular error probable - the radius within which 50% of the shots impact). 100% of the shots fell within 18 km of the target. A radio beam guidance update system was introduced in December 1944, which in tests produced a 2 km CEP. In reality, in the campaign against Britain, 518 rockets were recorded as falling in the Greater London Air Defence Zone of 1225 fired, implying an average CEP of 12 km."

Note that the "implied CEP" of 12km includes the effects of misinformation about where the rockets were landing (news of missiles hitting short of London was suppressed while news of missiles going long was reported, or fed to German intelligence via turned spies) as well as missiles which failed outright due to non-guidance problems, so the actual accuracy of the guidance system in the field was likely closer to the 2km-4.5km figures.

Russell Borogove
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Adding to Russell's answer:

A large hindrance to greater precision of the A-4 (technical name) was the lack of calibration data. At this late point in the war, the German intelligence network in the UK was compromised, giving the British secret service the ability to inject false information on the impact sites of the rockets. This lead the Germans to assume their rockets overshot London, so they re-targeted them to what was in fact the loosely populated area of Kent.

Additionally, many of the missiles burst on the last few hundred meters and failed to detonate, because of the static air pressure. This air burst problem was alleviated in 30 August 1944 tests by adding 'sleeves'/'tin trousers' to the forward end of the rocket. When von Braun's team conducted further tests at the elevated (1300m) plateau of White Sands, New Mexico, no such failures occurred.

Source: "Peenemunde to Canaveral" by Dieter Huzel

Janne
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Rikki-Tikki-Tavi
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  • Could you elaborate: Why is the air pressure important for the detonation? Is it just the height measurment? And: New Mexico? Did Braun's team perform those tests in the US before the war? Also: Sorry for reviving this old threat, just got curious anyway. – AtmosphericPrisonEscape Dec 04 '18 at 00:48
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    @AtmosphericPrisonEscape The high density of the air at ground level caused very high forces on the fast moving rockets, which lead to them collapsing before impact. This prevented the payload from exploding.

    After the war, German scientists were brought to America and had the opportunity to demonstrate captured A4 rockets at the White Sands Missile Range.

     – Rikki-Tikki-Tavi Dec 04 '18 at 11:02