Have you ever wondered why it has been a long time since we sent a manned mission to the Moon? Well, the answer lies in the ever-so-precarious process of landing on the moon and taking that first stem on the lunar surface. A recent YouTube video featuring none other than the first man to land on the moon Neil Armstrong is here to give us an understanding of why.
YouTube channel Smarter Every Day, run by an American engineer Destin Sandlin, talks about how the National Aeronautics and Space Administration (NASA) trained its astronauts to land on Moon when it sent its Apollo missions that landed a total of twelve astronauts from 1969 to 1972 in a series of Apollo missions numbering up to Apollo 17. The 22-minute video also featured a lecture delivered by Neil Armstrong in 2007 in front of Society of Experimental Test Pilots.
In the lecture, Armstrong talked about how the Flight Research Centre (now known as Armstrong Flight Research Centre) in 1962 proposed a Lunar Landing Simulator Program consisting of three parts: a preliminary study, a research test vehicle, and an Apollo flight simulator. The research test vehicle was small, relatively inexpensive, and independent of actual Apollo configuration. Armstrong mentions that the simulator was intended to investigate the inherent problems of lunar descents from altitudes up to 2000 feet and have the capacity to vary control characteristics, cockpit configurations displays and much more.
The simulations were necessary since the presence of gravitational force on the moon is much less than on earth. Hence, astronauts had to practice the landing techniques that would be different from how the landing of flying objects takes place on earth. NASA was thinking of landing on the moon in a way that is like that of a helicopter that lands by hovering over the ground.
However, the problem with that method was that a spacecraft had to tilt much more for the horizontal acceleration than a helicopter of the same mass. The horizontal acceleration was almost proportionate to the tilt angle of the rooter of the spacecraft. Armstrong explained that over moon where there is no atmosphere like earth to provide the drag and where its weight is 1/6th of that on the moon the same horizontal acceleration requires six times of the tilt angle.
The video then shows how in the 50s and 60s US had already developed an airplane that could land and take off vertically. Armstrong does mention it as the X-14 that the scientists thought could be used as a simulator, however, it could not simulate the effects of reduced gravity present on the moon.
After two failed vehicles, NASA’s Lunar Landing Research Facility (LLRF) duplicated Moon’s 1/6th weight aspect to simulate the landing of Apollo spacecraft. The vehicle’s apparent weight was lowered to its lunar equivalent by lifting upward by a vertical cable attached to a moving bridge crane. Armstrong described the complex hydraulic structure as an engineer’s delight.
However, even this method did not provide the pilot with the actual flying experience since the spacecraft was tied to a string. Then the FRC came up with the Lunar Landing Training Vehicle that modified the research vehicle into the 1/6th mass that would work on the lunar surface. It was this method that finally gave the astronauts the training on how to land on the moon.