This May 6th, 1968, footage from NASA shows a training vehicle used by Apollo
11 astronauts as they prepared to land the first man on the moon. In the clip,
astronaut Neil Armstrong flies 200 feet above Ellington Air Force Base in Houston,
Texas, in a mock lunar lander as it precariously wobbles in the air.
An experienced pilot of the Lunar Landing Research Vehicle, Armstrong already had over
20 recorded flights under his belt. However, the video shows the control thrusters abruptly fail,
shutting down aerodynamic maneuverability within seconds. The LLRV veers off course
and plummets towards the ground before impacting in a fireball.
Luckily, Armstrong comes down in a parachute,
unharmed by the disaster thanks to his quick reaction to abort.
LLRV Development
After his election, President John F. Kennedy had the difficult task of delivering on the promise
of landing the first man on the moon. In charge of this task, NASA dealt with the 'how' of the
mission. One of the most challenging aspects they faced was actually landing humans on the moon,
something both the United States and the USSR tried to solve for years.
Given several training tools, the astronauts were most excited to use the Lunar Landing
Research Vehicle and its follow-up the Lunar Landing Training Vehicle. In 1961,
NASA engineers and planners dedicated themselves to designing a machine that
would complement the vertical landing trials accomplished with helicopters and ground-based
simulators. That way, the astronauts could gain hands-on experience with a free-flying
simulator closely resembling the landing module. They needed to overcome several
obstacles, mainly replicating the moon's gravity, a sixth of that found on Earth.
The machine needed to operate as close to the actual Lunar Module as
possible in terms of controls, flight characteristics, and responsiveness.
Bell Aerosystems of Buffalo New York gained the contract for building the first LLRV,
a fly-by-wire aircraft. Relying on an interface with three analog computers,
the single pilot's movements would be converted to
electronic signals transmitted by wire, which would then respond to commands.
Perhaps unintentionally, the first LLRV helped develop digital fly-by-wire technology used in
other subsequent aircraft. Two copies of the craft were built for NASA by Bell.
Aside from lunar simulation, the machine functioned in a
wide variety of tasks. The device neutralized aerodynamic forces,
maintaining an engine thrust 5/6ths the weight of the vehicle itself. This led to the
most successful replication of zero-gravity conditions. The components and electronics
needed to be as advanced and sophisticated as any other technology around in the 1960s.
Armstrong would later speak about the vehicle, saying [QUOTE] "Eagle flew very much like the
Lunar Landing Training Vehicle, which I had flown more than 30 times…. I had made from 50 to 60
landings in the trainer, and the final trajectory I flew to the landing was very much like those
flown in practice. That, of course, gave me a good deal of confidence – a comfortable familiarity."
LLRV Testing
On October 30th, 1964, North American X-15 hypersonic rocket pilot Joe Walker conducted
the first LLRV flight. The flight lasted less than a minute, but the data acquired in that time
was not only valuable but also encouraging. Walker conducted two more flights that day.
During this initial testing phase, his backup, Don Mallick, as well as the rest of the test
pilots flew the LLRV 204 times. Each flight provided more and more feedback that went
into modifications. In fact, because of the test flights, engineers at NASA developed lunar landing
flight profiles in minute detail even before astronauts began training with the vehicle.
The data collected also proved helpful in building a succeeding vehicle. Despite the desire to use
a new model for training, time constraints and political pressure led NASA to use the LLRV as
a trainer for astronauts while the new vehicle was still under development. Unfortunately,
the first man to use the training vehicle, Joe Walker, never got to witness this
endeavor. In 1966, his F-104 aircraft crashed mid-air against an XB-70 Valkyrie Bomber.
LLRV Risks
When looking closely at the Lunar Landing Research Vehicle, some have assessed accurately that it was
not a perfect machine. While helpful and essential for the success of American space missions,
later on, training exercises weren't any less dangerous. The astronauts would often refer to
the vehicle as a "flying testbed," and were well aware of the risks associated with it.
Successfully piloting the machine was incredibly hard, but it also represented the difficulty
astronauts faced in handling the lunar module in outer space. The equipment was involved,
with complicated controls that were new and strange. Armstrong himself later
spoke out about challenges, describing flying the vehicle: [QUOTE] "the most
difficult part from my perspective, and the one that gave me the most pause."
Still, the NASA teams needed to train for the moon landing. They were required to
acclimate to conditions, but every aspect of the mission, including planting the flag on the moon,
had to be perfect. They also trained their survival skills extensively,
since a returning flight could miss its mark, instead throwing an astronaut into the wilderness.
Still, astronauts used the training vehicle. Armstrong's accident didn't deter him. After
ejecting and narrowly avoiding the ball of flames, he simply returned to the office,
finished out his workday, and went home as if nothing had happened. Before going on
his space mission, he continued to fly with the practice simulator 12 times.
Following the accident, the Manned Space Flight Center Director Rober L. Gilruth
ordered an investigation into the accident. Headed by Aircraft Operations Chief Joseph S. Algranti,
who'd also piloted the LLRV, the Center's study concluded that the root of the problem
lies in the loss of helium pressure. This pressure provoked the depletion
of hydrogen peroxide badly needed by the reserve attitude thrusters. Unfortunately,
the LLRV's instruments had not shown the expected warning.
Several engineers applied modifications that reduced the probability of a repeat
accident. Testing resumed in October, five months after the occurrence.
LLTV
Results from the testbeds and further technological developments led developers to
the LLTV or Lunar Landing Training Vehicle. It was introduced as the new and improved model in 1967.
This new vehicle enclosed a pilot on three sides while the cockpit had a
roof. This new cockpit replicated the view and enclosed space that astronauts would
have in their actual lunar module. Still and all, the roof had to be removed soon
after installation. The updated cockpit was interfering with the vehicle's ability to
compensate for excessive yaw. This issue led to a crash,
but thankfully test pilot Joe Algranti was able to eject safely and survive the ordeal.
The LLTV suffered similar issues. Like its predecessor, it was a challenging vehicle to fly,
perhaps even more so than the original. Gene Cernan, the commander for Apollo 17, stated:
[QUOTE] "The LLTV was inherently less stable than the LM itself,
and we also had to contend with gusts of wind that could cause problems."
Two more LLRVs were built, and the LLTV saw an equally small production roll-out, only three.
In total, 15 American astronauts linked to Apollo missions flew either the LLRV
or LLTV or both. Most were either mission commanders or second in command. However,
all who participated in the training with the machines had positive things to say. Armstrong
would even credit the success of his moon landing on his training and use of the LLTV.
He would go on to say, [QUOTE] "It was a contrary machine and a risky machine,
but a very useful one."