|A slightly haggard-looking William "Pete" Knight walks away from X-15A-2|
on October 3, 1967, after setting a world record speed of 4,534 mph.
Even though the X-15's Inconel skin is, by nature, quite heat tolerant, the aerodynamic heating that was expected at the speeds that the record flights were to be flown far exceeded even this exotic metal. To deal with this, the engineers decided to cover the rocket plane's skin with an ablative, or heat-resistant coating.
This rubbery, pencil eraser-like material had the unfortunate property of also being bright pink.
|An official photo of A-2 from the NASA Dryden website.|
The urban legend, told in the hallways at Dryden, however, is that Pete Knight walked into the coatings hangar after the ablative had been applied, and said, "Like hell, I'm gonna fly a pink airplane!" And shortly thereafter, the white coating was added.