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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?

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    $\begingroup$ 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. $\endgroup$ – gerrit Mar 12 '15 at 16:12
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    $\begingroup$ @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. $\endgroup$ – Deer Hunter Mar 12 '15 at 19:08
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    $\begingroup$ 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. $\endgroup$ – Mark Adler Mar 12 '15 at 20:36
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    $\begingroup$ Rocketry in general has been considered on topic. I say this is on topic here, and a reasonable question. $\endgroup$ – PearsonArtPhoto Mar 12 '15 at 22:59
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    $\begingroup$ @gerrit - absolutely. You want precise orbit insertion and reentry. $\endgroup$ – Deer Hunter Mar 13 '15 at 4:26
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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.

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  • $\begingroup$ Another discussion where Astronautix article is cited: How Effective A Weapon Was the V-2 Rocket?. $\endgroup$ – mins Mar 12 '15 at 18:20
  • $\begingroup$ For those curious, this article explains the Myth of V2 Inaccuracy and Ineffectiveness. To be compared to Astronautix article. Feel free to point out blatant distorsions if appropriate. $\endgroup$ – mins Mar 12 '15 at 18:30
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    $\begingroup$ Ah, I get it. The Astronautix article isn't saying anything incorrect (4.5km CEP or better), but it's leaving out that the implied CEP in practice included intelligence countermeasures. $\endgroup$ – Russell Borogove Mar 12 '15 at 18:35
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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. When von Braun's team conducted further tests at the elevated (1300m) plateau of White Sands, New Mexico, no such failures occured.

Source: "Peenemunde to Canaveral" by Dieter Huzel

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  • $\begingroup$ 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. $\endgroup$ – AtmosphericPrisonEscape Dec 4 '18 at 0:48
  • $\begingroup$ @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. $\endgroup$ – Rikki-Tikki-Tavi Dec 4 '18 at 11:02

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