 Who is this handsome gentleman, and why am I smiling like an absolute goon sitting down to interview him? I'm Aimee Shearer Tidal, and today on Vintage Space, we're talking about, and speaking with, Joe Engel. Of the 185 different types of aircraft Joe Engel piloted in his career, including the Space Shuttle, he told me that the X-15 was his all-time favorite. Last weekend at the San Diego Air and Space Museum's Hall of Fame induction ceremony, I got to sit down with him and talk about it. The X-15 was conceived in the early 1950s as a research airplane designed to gather data on flight at speeds up to Mach 7 and at altitudes up to 50 miles. When the vehicle was rolled out in October of 1958, it looked about as futuristic as its high-speed high-altitude flight profile would suggest. The X-15 is basically a missile with wings and room for a pilot. It was even air-launched from underneath the wing of a B-52 bomber like a missile. 50 feet long, 13 feet high, and with a wingspan just 22 feet across. Most of the X-15's body was taken up by tanks of anhydrous ammonia and liquid oxygen, designed to fuel the XLR-99 engine in the back. Though it's worth mentioning that some of the earlier X-15 flights used the Ethel alcohol-propelled XLR-11 engines. The X-15 also featured reaction controls, small hydrogen peroxide jets on the aircraft's body that would give the pilot control over his attitude at altitudes where traditional flight controls just didn't have enough air to bite into. Because it used these two very different flight control systems and used them seamlessly on one flight, Engel told me that learning how to pilot the X-15 was actually quite difficult. A typical X-15 flight had the pilot ignite his rocket engine in a steep climb for maximum altitude, meaning he needed to use the reaction controls at the top of his arcing path and traditional flight controls for the unpowered descent and landing. Luckily for Engel, his flight's built up to these high-altitude runs. His first flight, like every X-15 pilot's first flight, was just a check-out flight so that he had a chance to familiarize himself with how the airplane flew in the atmosphere. Things got more demanding from there. On June 29th of 1965, Engel piloted the X-15 to a peak altitude of 280,600 feet. That's 53.1 miles, and 3.1 miles above the threshold where air ends and space begins. He qualified for astronaut wings on that flight. As a non-pilot, the top of the X-15's flight has always kind of terrified me. The view from the top with the Earth curving below you is beautiful, but knowing what you're in is basically a winged missile and with nothing but your skill to get you home safely kind of freaks me out. And so I asked Engel about the fear factor of the X-15 flight profile. Whether at any point in any flight, he stopped for just half a second to think about the reality of where he was and what he was doing. And like a true ace pilot, Engel said he was never really rattled by the flights. He used the window as a flight instrument. The X-15 didn't have an inertial guidance system. Instead, it used mechanical gyros that had a tendency to drift in flight. So the window was actually a useful tool in checking that he was oriented properly for re-entry and descent. And really, he said there was so much going on inside the cockpit during an X-15 flight, he didn't have time to stop and really think about what was going on. But after saying all that, Engel did laugh and relent just a little bit. He said that being an X-15 pilot meant you had to bring your A-game to work every single day. And that being at the top of that flight profile, knowing that you were the only one who could get yourself home safely, you had to trust that your hands were the greatest hands in the entire world. Engel told me that the curvature of the earth didn't become scenery until he went into space on STS-2. On that flight, he finally had a chance to just stop and look. Joe Engel described the X-15 as a raw nuts and bolts airplane, the kind of airplane that is professionally extremely rewarding to fly. And I might add, he could not have been nicer to sit down and talk to. So what do you guys think? Having a little bit more insight into how the X-15 flew? Do you think you'd be able to handle seeing the earth curving beneath you knowing that you had only the skill in your hands to get yourself back home? Let me know in the comments below and share your thoughts on the X-15 program. And for more on the X-15 and my conversation with Joe Engel, check out the latest blog post over on Vintage Space at Popular Science. You can find me on Twitter for nearly daily old-timey space updates as AST Vintage Space. And for weekly Vintage Space video updates, don't forget to subscribe.