Nice story but not true. Hobo Queen was reportedly part of a disinformation program to make the Germans think the B-29 would be deployed in Europe, so it did a tour of several British airfields and then continued on its way to the CBI. It wasn't there to test any new bombing radar over occupied Europe. Project Ruby was post-war, taking place in 1946 to test the effects of large bombs on hardened concrete fortifications.
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