There hadn't been much effort to bother investigating the outer limits of performance in piloting between sexes prior to the Mercury Thirteen.

Heinlein dealt in speculative fiction. in 1959, it was plausible.

It was false, but it was plausible.

There hadn't been much effort to bother investigating the outer limits of performance between sexes prior to the Mercury Thirteen.

But it was well known that Reitsch had flown a helicopter indoors repeatedly, and even flew a modified V1 to solve some stability issues when no male pilot was able to fit into the thing.

Heinlein dealt in speculative fiction. in 1959, it was plausible.

It was false, but it was plausible.