 At the April 1956 public unveiling of the YF-104A, the engine inlets were obscured with metal covers; visible weapons, including the M61 Vulcan cannon, were also hidden.Despite the secrecy, an artist's rendering of the yet-unseen F-104 appeared in the September 1954 edition of "Popular Mechanics" that was very close to the actual design.The prototype made a hop into the air during taxi trials on 28 February 1954 and flew about off the ground for a short distance, but this was not counted as a first flight.