Aug 26, 2012

Farewell Neil Armstrong, the Ultimate Test Pilot

Neil Armstrong — who has died at the age of 82 — was best known as the commander of Apollo 11, but his career at NASA began nearly a decade earlier as a research test pilot.

A trained aerospace engineer, Armstrong was a self-described “white-socks, pocket-protector, nerdy engineer” who worked at the cutting edge of flight test throughout the 1960s, flying everything from a hang-glider type aircraft towed behind a biplane, to a hypersonic rocket-powered airplane that flew to the edge of space.

Neil Armstrong was born in Wapakoneta, Ohio and first began building model airplanes while in elementary school. He told biographer James Hansen he initially wanted to be an airplane designer, but “later went into piloting because I thought a good designer ought to know the operational aspects of an airplane.”

The future astronaut soloed an airplane just a few weeks after his sixteenth birthday. Before being selected as an astronaut, Armstrong was a naval aviator flying F9F Panther fighter jets in the Korean War. After the war, he became a research pilot for the National Advisory Committee for Aeronautics, the predecessor to NASA. While a research pilot NACA and later NASA, he flew the rocket powered Bell X-1B and the North American X-15 along with a wide variety of jet and propeller aircraft totaling more than 200 different types.

During his time in the X-15 program, Armstrong demonstrated his engineering skills working on the hypersonic aircraft’s flight control system as well as the relatively primitive simulator used to develop flight profiles of the first winged aircraft to fly into space. During his highest of seven flights in the X-15, he climbed to 207,500 feet. After the engine stopped (as planned) and he was gliding back to land, Armstrong was testing a new control system when he bounced off the top of the atmosphere, skipping past Edwards Air Force Base in the Mojave Desert and not getting the rocket airplane turned around until flying near Pasadena.

He was fifty miles south of his landing spot in a rocket plane that was now a rather poor glider. But the calm engineer says, “that wasn’t a great concern to me because there were other dry lakes available.” He would later call the longest X-15 flight of all “a learning thing.” The entire flight lasted just 12 minutes, 28 seconds.

At the same time Armstrong was working on the X-15 program, he also worked on the Boeing X-20 Dyna-Soar project, part of the Air Force’s ‘Man in Space Soonest’ program. The X-20 was to be a winged spacecraft that was an early predecessor to the space shuttle orbiters. As a test pilot and engineer, Armstrong flew a modified Douglas F5D fighter jet — now on display at the Neil Armstrong Museum in Wapakoneta — on a series of flights to develop launch abort procedures that were to be used for the winged X-20 spacecraft.

Armstrong’s quiet engineering demeanor was perhaps best demonstrated after a flight in the Lunar Lander Training Vehicle (LLTV). Affectionately known as the “flying bedsteads,” the LLTV was used to train astronauts who would be making approaches to the lunar surface and was basically a large jet engine pointed downward and small thrusters that could control the attitude of the vehicle during flight.

It was considered a very difficult, and dangerous aircraft to fly. On a LLTV flight in 1968, Armstrong lost control of the aircraft due to a propellant leak and windy conditions. He ejected only moments before it crashed in a fireball. According to James Hansen’s biography, an hour or so later fellow astronaut Alan Bean returned to his desk after lunch and found Armstrong at his own desk simply “shuffling some papers.” Bean didn’t believe what others had told him about the crash so he asked Armstrong who replied, “I lost control and had to bail out of the darn thing.”

At a meeting of the Society of Experimental Test Pilots in 2007, Armstrong described the development and use of the LLTV.

Armstrong joined the astronaut corps as part of the “new nine” and first flew on Gemini 8 along with David Scott. The Gemini 8 mission was set to make the first rendezvous and docking with another spacecraft in orbit to test docking procedures. Upon docking with the Agena, an unmanned target vehicle, the Gemini spacecraft and Agena began spinning. Armstrong disconnected from the Agena and then began spinning even faster, approximately one revolution per second. Facing an unplanned flight test kind situation once again, Armstrong put his experience as a test pilot and engineer to work and decided to use the reentry control system to slow down the rotation. The solution worked, but cut short the flight which ended after less than 11 hours.

After the Gemini flight experience, Armstrong was the backup commander for Gemini 11 but did not fly to space. He was then selected as backup commander for Apollo 8, the first mission to leave earth orbit and circle the moon. In December of 1968, while Apollo 8 was still in space, Armstrong was offered the commander position for Apollo 11. At the time, there was no guarantee that meant he would be commanding the mission to the moon. There was still plenty that could go wrong forcing a delay and bumping a moon landing to Apollo 12 or later.

Apollo 8 was only the third flight for the massive Saturn V rocket, and the first carrying astronauts. The mission combined several tests that were initially expected to be spread over a few flights. The bold decision to proceed and successful Apollo 8 mission were critical in making Armstrong’s Apollo 11 flight to the moon possible. Armstrong later said in his biography: “I cannot imagine NASA management in any subsequent period of time being willing to take that kind of step.”

Of course, it was less than a year later that Armstrong himself would make the biggest step. After a three day trip to the moon, Armstrong, Aldrin and Collins entered lunar orbit on July 19. On July 20, Armstrong and Aldrin began their descent towards the surface inside Eagle, the lunar landing module. The flight to the surface did not quite go as planned. During the descent several alarms from the flight guidance computer distracted the astronauts. The onboard computers were inundated with extraneous radar information, but the alarms were determined not to be a problem.

But Armstrong also noticed he and Aldrin were flying faster than expected across the lunar surface and were likely going to overshoot their landing site. As the Eagle passed 1,500 feet above the surface, Armstrong saw they were heading for a crater. He thought this might be a good option as it would have “more scientific value to be close to a large crater.” But the steep slope and big rocks did not provide a safe place to land.

As they continued to fly over areas covered with large rocks and boulders, Armstrong took over control of the Eagle and continued flying it manually. He was able to use his training from the LLTV to maneuver as they continued to descend to the surface. But all of the maneuvering was using up propellant. At 200 feet above the surface, Armstrong finally was able to find a place to land.

Aldrin: Eleven [feet per second] forward. Coming down nicely. Two hundred feet, four and a half down.
Armstrong: Gonna be right over that crater.
Aldrin: Five and a half down.
Armstrong: I got a good spot.
Aldrin: One hundred and sixty feet, six and a half down. Five and a half down, nine forward. You’re looking good.

As they passed 75 feet mission control in Houston determined the Eagle only had 60 seconds of fuel left. Armstrong says he wasn’t terribly concerned about the low fuel situation, “typically in the LLTV it wasn’t unusual to land with 15 seconds left of fuel.”

About 40 seconds later Armstrong made a final few maneuvers before announcing the landing was complete.

Armstrong: Shutdown.
Aldrin: Okay. Engine stop.
Houston: We copy you down, Eagle.
Armstrong: Houston, Tranquility Base here. The Eagle has landed.

It was later determined the Eagle had about 50 seconds of fuel left for maneuvering. Most remember Neil Armstrong as the first person to walk on the moon. As a test pilot, he often referred to being the first person to land a spacecraft on the moon, something he liked to point out was the more challenging part of the mission from his point of view.

After his historic descent down the ladder and making his “giant leap for mankind” Armstrong and Aldrin would spend just two hours and 36 minutes on the surface of the moon.

Read more at Wired Science

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