 Most of us have been inside an airplane that's landed on a runway on wheels. It's something we're pretty familiar with. But landing on the moon? The Apollo lunar module was a very different vehicle that required a very different set of skills to land. So how did the Apollo astronauts learn to land something this unconventional on the moon? In the equally unconventional, but very effective lunar landing research vehicle. Landing on the moon isn't at all like landing on Earth. The moon has no atmosphere and only 1 sixth the gravity we experience, conditions that are impossible to replicate. But the lunar landing research vehicle offered astronauts a pretty good simulation. Made of aluminum alloy trusses, it was shaped like a giant four-legged bedstead. And like the lunar module, it took off and landed vertically, thanks to the turbofan engine mounted in a gimbal underneath it. During a training flight, an astronaut would fire the engine at full power to get the vehicle up to test altitude. Then he'd throttle the engine back so it was supporting 5 sixth of the vehicle's weight, simulating the reduced gravity of the moon. He could control his rate of descent using two variable thrust rockets, while 16 smaller rockets mounted in pairs gave him attitude control around all three axes, pitch, yaw, and roll. The gimbal allowed the vehicle to rotate freely around its axes, simulating the movement of the lunar module in an airless environment. In this configuration, he'd make a practice landing. The unconventional and awkward vehicle did the trick. After returning from the moon, Neil Armstrong said the lunar landing research vehicle had been a vital part in his successful landing in the Sea of Tranquility. His praise came in spite of a nearly fatal crash during a 1968 training flight. But that's another story. And now you know how to practice for a landing on the moon.