Question: The Bell X-1 was an aircraft piloted at a supersonic level by the test pilot who served in what branch of the armed forces?
Sentence (from "Bell X-1"): The X-1, piloted by Chuck Yeager, was the first manned airplane to exceed the speed of sound in level flight and was the first of the X-planes, a series of American experimental rocket planes (and non-rocket planes) designated for testing of new technologies and often kept secret.
Relevant evidence: Yes