 Hey guys, we've talked about reaction controls a little bit before in this video right here. And what's really interesting is how pilots first learned how to fly these space-age controls in an era before spaceflight. And that's what we're talking about today on Vintage Space. Reaction controls are used to orient a spacecraft in a vacuum. They eject a small amount of pressurized gas to affect very small motions to the spacecraft's attitude or orientation. The same basic system is used in high-altitude aircraft, when there's not enough atmosphere for traditional flight controls to fish against. Again, there's a little bit more on that in this video right here. It was clear in the mid-1950s that aircraft would be going to near-space altitudes before long, so pilots had to figure out how to fly with these space-age controls. Enter the Iron Cross Attitude Simulator. It was built by engineers at the NACA's high-speed flight station, the Fairleigh Spartan Research Center at Edwards Air Force Base in California's Mojave Desert. It was made of steel girders put together in the form of a cross, with the center pivot on a truck's universal joints, which had freedom of motion around its pitch, yaw, and roll axes. On the ends of the girders were nitrogen-powered thrust rockets. The four ends of the cross were meant to simulate the four tips of an aircraft, the nose, the tail, and the two wingtips. On each of those ends was a reaction control, a small thrust rocket that shot out pressurized nitrogen gas to affect a small motion. On the forward end of one of the girders was an open seat facing away from the central pivot. And facing the seat was a simple display of three instruments, showing information about the aircraft's pitch and bank angles, as well as its angle of sideslip. This turned the seat into basically a simplified open cockpit. So pilots would sit in the seat and use the information on the displays to engage the thrust rockets, bursts of compressed gas moving the cross on its universal joint. Control came from a simple control stick and the pilot's left hand. Roll was maneuverable by twisting the wrist, and pitch was maneuvered by pushing the stick forward and backwards. The hardest part for the pilot was figuring out just how much thrust was needed to balance out the iron cross. And the displays weren't exactly great. They barely correlated to the real thing, such that some pilots who trained on the iron cross found that the simulation really didn't help them that much when they found themselves at altitude flying with reaction controls. In 1957, several hydrogen peroxide rockets were mounted on the wingtip, aft fuselage, and tail of an X-1B, that's a second generation X-1. The idea was to test them out in low dynamic pressure, that is, when the atmosphere was too thin for traditional flight controls. Neil Armstrong flew the X-1B four times. The last three flights all tested the reaction controls, which was probably pretty good practice for when he used them on his X-15 flights, and not to mention when he needed them to land the Lunar Module Eagle on the moon in 1969. So after learning a little bit about reaction controls and how they were tested, do you guys have any more questions? Let me know in the comments below, and don't forget to follow me on Twitter as AST Vintage Space for daily old-timey space updates. And, of course, with new episodes going up every single Tuesday and Friday right here, subscribe so you never miss an episode.