Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

The Soviets kept the details and true appearance of the Vostok capsule secret until the April 1965 Moscow Economic Exhibition, where it was first displayed without its aerodynamic nose cone concealing the spherical capsule. The "Vostok spaceship" had been first displayed at the July 1961 Tushino air show, mounted on its launch vehicle's third stage, with the nose cone in place. A tail section with eight fins was also added, in an apparent attempt to confuse western observers. This spurious tail section also appeared on official commemorative stamps and a documentary.
At what event was the Vostok spaceship first displayed to the public ?