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58-440: The research vehicles were vertical take-off vehicles that used a single jet engine mounted on a gimbal so that it always pointed vertically. It was adjusted to cancel 5/6 of the vehicle's weight, and the vehicle used hydrogen peroxide rockets which could fairly accurately simulate the behavior of a lunar lander. Success of the two LLRVs led to the building of three Lunar Landing Training Vehicles ( LLTVs ), an improved version of

116-406: A Cardan suspension after Italian mathematician and physicist Gerolamo Cardano (1501–1576) who described it in detail. However, Cardano did not invent the gimbal, nor did he claim to. The device has been known since antiquity, first described in the 3rd c. BC by Philo of Byzantium , although some modern authors support the view that it may not have a single identifiable inventor. The gimbal

174-675: A closed cell foam that resists moisture. The patent on this adaptation was filed in 1947. Styrofoam has a variety of uses. Styrofoam is composed of 98% air, making it lightweight and buoyant. DuPont produces styrofoam building materials, including varieties of building insulation sheathing and pipe insulation. The claimed R-value of styrofoam insulation is approximately 5 °F⋅ft ⋅h/BTU for 1 inch thick sheet. Styrofoam can be used under roads and other structures to prevent soil disturbances due to freezing and thawing. DuPont also produces styrofoam blocks and other shapes for use by florists and in craft products. DuPont insulation styrofoam has

232-594: A company with experience in vertical takeoff and landing ( VTOL ) aircraft, NASA issued Bell a $ 50,000 study contract in December 1961. Bell had independently conceived a similar, free-flying simulator, and out of this study came the NASA Headquarters' endorsement of the LLRV concept, resulting in a $ 3.6 million production contract awarded to Bell on February 1, 1963, for delivery of the first of two vehicles for flight studies at

290-432: A distinctive blue color; styrofoam for craft applications is available in white and green. The EPA and International Agency for Research on Cancer reported limited evidence that styrene is carcinogenic for humans and experimental animals , meaning that there is a positive association between exposure and cancer and that causality is credible, but that other explanations cannot be confidently excluded. See also

348-719: A lens around its center of gravity , thus allowing for easy and smooth manipulation while tracking moving subjects. Very large gimbal mounts in the form 2 or 3 axis altitude-altitude mounts are used in satellite photography for tracking purposes. Gyrostabilized gimbals which house multiple sensors are also used for airborne surveillance applications including airborne law enforcement, pipe and power line inspection, mapping , and ISR ( intelligence, surveillance, and reconnaissance ). Sensors include thermal imaging , daylight, low light cameras as well as laser range finder , and illuminators . Gimbal systems are also used in scientific optics equipment. For example, they are used to rotate

406-414: A material sample along an axis to study their angular dependence of optical properties. Handheld 3-axis gimbals are used in stabilization systems designed to give the camera operator the independence of handheld shooting without camera vibration or shake. There are two versions of such stabilization systems: mechanical and motorized. Mechanical gimbals have the sled, which includes the top stage where

464-466: A portable warming stove to Empress Wu Zetian (r. 690–705) which employed gimbals. Extant specimens of Chinese gimbals used for incense burners date to the early Tang dynasty (618–907), and were part of the silver -smithing tradition in China. The authenticity of Philo's description of a cardan suspension has been doubted by some authors on the ground that the part of Philo's Pneumatica which describes

522-706: A preliminary flight envelope for the LLTV, defining its allowable maximum airspeed at various angles of angle of attack and sideslip. All this had to be verified by flight test, however, since it was not possible in the tunnel to obtain good data with the engine running. A high level LLTV Flight Readiness Review Board was appointed on March 5, 1969 by JSC Director Dr. Robert Gilruth . It consisted of him as chairman, with board members Chris Kraft , head of Mission Operations; George Low , head of JSC's Apollo Program; Max Faget , JSC's Director of Engineering and astronaut Deke Slayton , Director of Flight Crew Operations. The board reviewed

580-418: A view recently also shared by the classicist Andrew Wilson (2002). The ancient Roman author Athenaeus Mechanicus , writing during the reign of Augustus (30 BC–14 AD), described the military use of a gimbal-like mechanism, calling it "little ape" ( pithêkion ). When preparing to attack coastal towns from the sea-side, military engineers used to yoke merchant-ships together to take the siege machines up to

638-492: A water barrier. This material is light blue in color and is owned and manufactured by DuPont . DuPont also has produced a line of green and white foam shapes for use in crafts and floral arrangements. The term styrofoam is often used in the United States as a colloquial term to refer to expanded (not extruded) polystyrene foam ( EPS ). Outside the United States, EPS is most commonly referred to as simply "polystyrene" with

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696-523: Is misleading: no gimbal is restrained. All three gimbals can still rotate freely about their respective axes of suspension. Nevertheless, because of the parallel orientation of two of the gimbals' axes there is no gimbal available to accommodate rotation about one axis. Styrofoam Styrofoam is a genericized trademarked brand of closed-cell extruded polystyrene foam (XPS), manufactured to provide continuous building insulation board used in walls, roofs, and foundations as thermal insulation and as

754-652: Is on display as an artifact of the center's contribution to the Apollo program. Negotiations between JSC and Bell Aerosystems for three LLTVs (LLTV-1 to 3), an improved training version of the LLRV, were initiated in October 1966 and a $ 5.9 million contract for three vehicles was finally signed in March 1967. In June 1968, the first vehicle (LLTV-1) was delivered by Bell to Ellington to begin its ground and flight testing by JSC's Aircraft Operations Division (AOD). AOD's head, Joe Algranti,

812-573: Is safe to assume the Arabic version is a faithful copying of Philo's original, and credits Philon explicitly with the invention. So does his colleague Michael Lewis (2001). In fact, research by the latter scholar (1997) demonstrates that the Arab copy contains sequences of Greek letters which fell out of use after the 1st century, thereby strengthening the case that it is a faithful copy of the Hellenistic original,

870-449: Is sensitive to its orientation. Because of this, chronometers were normally mounted on gimbals, in order to isolate them from the rocking motions of a ship at sea. Gimbal lock is the loss of one degree of freedom in a three-dimensional, three-gimbal mechanism that occurs when the axes of two of the three gimbals are driven into a parallel configuration, "locking" the system into rotation in a degenerate two-dimensional space. The word lock

928-496: The Little Key of Painting' ( mappae clavicula ). The French inventor Villard de Honnecourt depicts a set of gimbals in his sketchbook (see right). In the early modern period, dry compasses were suspended in gimbals. In inertial navigation, as applied to ships and submarines, a minimum of three gimbals are needed to allow an inertial navigation system (stable table) to remain fixed in inertial space, compensating for changes in

986-535: The Apollo Program". Although Armstrong had to eject from the LLRV, no other astronaut ever had to eject from the LLTV, and every Lunar Module pilot through the final Apollo 17 mission trained in the LLTV and flew to a landing on the Moon successfully. In January 1971 LLTV-2 was destroyed while testing a major modification to the computer system. Its test pilot, Stuart Present, was able to eject safely. Gene Cernan piloted

1044-586: The FRC within 14 months. LLRV-1 was shipped from Bell to FRC in April. LLRV-2 was also shipped at the same time, but in parts. Because of a potential cost overrun, the FRC Director, Paul Bickle, decided to have it assembled and tested at FRC. The emphasis then was on LLRV-1. It was first readied for flight on a tilt table constructed at FRC to evaluate its engine operation without actually flying it. The scene then shifted to

1102-631: The LLRV, for use by Apollo astronauts at the Manned Spacecraft Center in Houston, Texas, predecessor of NASA's Johnson Space Center . One LLRV and two LLTVs were destroyed in crashes, but the rocket ejection seat system safely recovered the pilot in all cases. The final phase of every Apollo landing was manually piloted by the mission commander. Because of landing site selection problems, Neil Armstrong , Apollo 11 commander, said his mission would not have been successful without extensive training on

1160-494: The LLRVs were powered by a General Electric CF700-2V turbofan engine with a thrust of 4,200 lbf (19 kN), mounted vertically in a gimbal . The engine lifted the vehicle to the test altitude and was then throttled back to support five-sixths of the vehicle's weight, simulating the reduced gravity of the Moon. Two hydrogen peroxide lift rockets with thrust that could be varied from 100 to 500 lbf (440 to 2,200 N) handled

1218-477: The LLTVs. Selection for LLTV training was preceded by helicopter training. In a 2009 interview, astronaut Curt Michel stated, "For airborne craft, the helicopter was the closest in terms of characteristics to the lunar lander. So if you didn't get helicopter training, you knew you weren't going. That sort of gave it away." Even Tom Stafford and Gene Cernan did not get LLTV training for their Apollo 10 mission which

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1276-470: The Space Center. 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. In Armstrong's 2005 authorized biography First Man: The Life of Neil A. Armstrong , astronaut Bill Anders is quoted as describing the LLTV as "a much unsung hero of

1334-482: The camera is attached, the post which in most models can be extended, with the monitor and batteries at the bottom to counterbalance the camera weight. This is how the Steadicam stays upright, by simply making the bottom slightly heavier than the top, pivoting at the gimbal. This leaves the center of gravity of the whole rig, however heavy it may be, exactly at the operator's fingertip, allowing deft and finite control of

1392-472: The camera to seem as if it is floating through the air, an effect achieved by a Steadicam in the past. Gimbals can be mounted to cars and other vehicles such as drones , where vibrations or other unexpected movements would make tripods or other camera mounts unacceptable. An example which is popular in the live TV broadcast industry, is the Newton 3-axis camera gimbal . The rate of a mechanical marine chronometer

1450-457: The cause of the divergence was the Styrofoam cockpit enclosure. As the vehicle's sideslip angle reached minus two degrees, a yawing force rapidly built up that exceeded the ability of the yaw thrusters to counteract. The fix decided on was simply to remove the top of the enclosure, thus venting it and eliminating the excessive yawing force. It was also possible from the wind tunnel results to develop

1508-504: The cockpits of both LLRVs to better simulate the actual Lunar Module. These included the addition of the LM's three-axis hand controller and throttle. A Styrofoam cockpit enclosure was also added to simulate the pilot's restricted view in the LM. The final LLRV flight at FRC took place on November 30, 1966. In December 1966, vehicle #1 was shipped to Houston, followed by #2 in January 1967. During

1566-484: The effect it produced was called "Lunar Sim Mode." This was the highest degree of hardware-based simulation. It was not a system to unburden the pilot, as an autopilot does, nor was it meant to introduce any sort of safety or economy. Lunar Sim Mode can also be thought of as a mixture of stability augmentation, recalculation of vertical acceleration according to the lunar gravity constant, all followed by accompanied instantaneous corrective action. The LLRV's Lunar Sim Mode

1624-414: The ground controllers had elected not to monitor in real time the attitude thrusters that controlled the vehicle's yaw motion, and, at the velocity Algranti was flying, the thrusters had been overpowered by the LLTV's aerodynamic forces, causing Algranti to lose control. Due to tight cost constraints on the LLRV and LLTV, wind tunnel testing had been avoided in favor of careful flight testing for evaluation of

1682-412: The innermost gimbal to remain independent of the rotation of its support (e.g. vertical in the first animation). For example, on a ship, the gyroscopes , shipboard compasses , stoves , and even drink holders typically use gimbals to keep them upright with respect to the horizon despite the ship's pitching and rolling . The gimbal suspension used for mounting compasses and the like is sometimes called

1740-573: The old South Base area of Edwards. The first three flights of #1 were made on October 30, 1964 by FRC's senior research test pilot, Joe Walker . He continued to pilot a number of flights through December 1964, after which flights were shared with Don Mallick , also a FRC research pilot, and Jack Kleuver, the Army's senior helicopter test pilot. Familiarization flights were also made by NASA Manned Spacecraft Center (later Johnson Space Center) pilots Joseph Algranti and H.E. Ream. Modifications were later made to

1798-416: The other astronauts, that if a serious control problem developed, the pilot had little choice but to eject, since the vehicle only operated to a maximum altitude of 500 feet (200 m). On May 6, 1968, Armstrong was forced to use LLRV-1's ejection seat from about 200 feet (60 m) altitude after a control problem, and had about four seconds on his full parachute before landing on the ground unhurt. LLRV-1

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1856-661: The pilot is faced with the situation of about 5/6 of his translational maneuvering performance removed from that on earth which is a marked change. Deke Slayton , then NASA's Chief Astronaut , later said there was no way to simulate a Moon landing except by flying the LLRV. General characteristics Performance The electronic control system for the Lunar Landing Training Vehicle was developed for NASA by Bell Aerosystems , Inc. which had engineering facilities located in Niagara Falls , New York . The LLTV

1914-400: The pilot's parachute could be automatically and successfully deployed. Manufactured by Weber Aircraft LLC , it was one of the first zero-zero ejection seats , capable of saving the operator even if the aircraft was stationary on the ground, a necessity given the LLRV's low and slow flight envelope. After conceptual planning and meetings with engineers from Bell Aerosystems, Buffalo, New York,

1972-543: The pot is turned. In Ancient China , the Han dynasty (202 BC – 220 AD) inventor and mechanical engineer Ding Huan created a gimbal incense burner around 180 AD. There is a hint in the writing of the earlier Sima Xiangru (179–117 BC) that the gimbal existed in China since the 2nd century BC. There is mention during the Liang dynasty (502–557) that gimbals were used for hinges of doors and windows, while an artisan once presented

2030-483: The preceding two years, a total of 198 flights of LLRV-1 and six flights of LLRV-2 had been flown without a serious accident. The first LLRV flight by Neil Armstrong was made in vehicle #1 on March 27, 1967 from its base at a corner of Ellington Air Force Base , the headquarters for Johnson Space Center's aircraft operations. Joe Algranti, chief of JSC's Aircraft Operations Division, and test pilot H.E. Ream also made flights that month. Both observed, as did Armstrong and

2088-440: The propellants and solvents of spray paint . In the 1940s, researchers, originally at Dow 's Chemical Physics Lab, led by Ray McIntire , found a way to make foamed polystyrene . They rediscovered a method first used by Swedish inventor Carl Georg Munters , and obtained an exclusive license to Munters's patent in the United States. Dow found ways to adapt Munters's method to make large quantities of extruded polystyrene as

2146-455: The ship's yaw, pitch, and roll. In this application, the inertial measurement unit (IMU) is equipped with three orthogonally mounted gyros to sense rotation about all axes in three-dimensional space. The gyro outputs are kept to a null through drive motors on each gimbal axis, to maintain the orientation of the IMU. To accomplish this, the gyro error signals are passed through " resolvers " mounted on

2204-468: The surviving LLTV-3 vehicle on November 13, 1972, three weeks before Apollo 17. LLTV-3 (NASA 952) is now on display at the Johnson Space Center . There were two distinct modes of flight for the LLRV and LLTV. The basic mode was with the engine fixed so that it remained 'normal' with respect to the body. In the gimbaled "Lunar Sim Mode," the free-gimbaled turbofan engine was allowed to swivel and

2262-505: The term "styrofoam" being used in its capacity to describe all forms of extruded polystyrene, not just the Dupont brand itself. Polystyrene (EPS) is often used in food containers , coffee cups, and as cushioning material in packaging . Styrofoam is, however, a far less dense material than EPS and is more commonly suited to tasks such as thermal insulation . Additionally, it is moderately soluble in many organic solvents, cyanoacrylate , and

2320-498: The three LLTV vehicles is on display at the Johnson Spacecraft Center in Houston, Texas. The electronic control system was designed with redundant channels that used 2 of 2 logic. The outputs of each primary channel were compared on a continuous basis. If a fault was detected in the primary control system, then control was automatically switched to an identical backup channel and the pilot immediately took measures to bring

2378-498: The three gimbal rings to align with their pivot axes in a single plane. When this occurs, it is no longer possible to maintain the sensing platform's orientation. In spacecraft propulsion , rocket engines are generally mounted on a pair of gimbals to allow a single engine to vector thrust about both the pitch and yaw axes; or sometimes just one axis is provided per engine. To control roll, twin engines with differential pitch or yaw control signals are used to provide torque about

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2436-451: The three gimbals, roll, pitch and yaw. These resolvers perform an automatic matrix transformation according to each gimbal angle, so that the required torques are delivered to the appropriate gimbal axis. The yaw torques must be resolved by roll and pitch transformations. The gimbal angle is never measured. Similar sensing platforms are used on aircraft. In inertial navigation systems, gimbal lock may occur when vehicle rotation causes two of

2494-510: The use of the gimbal survived only in an Arabic translation of the early 9th century. Thus, as late as 1965, the sinologist Joseph Needham suspected Arab interpolation . However, Carra de Vaux, author of the French translation which still provides the basis for modern scholars, regards the Pneumatics as essentially genuine. The historian of technology George Sarton (1959) also asserts that it

2552-425: The vehicle is reduced from a very positive high response vehicle to a very low or weak response vehicle. I'm sure with training and experience the pilot will be able to increase the overall vehicle-pilot performance once he adapts to the low translational accelerations that are available, as well as the lag that follows along with the anticipation that is required to properly control the vehicle. Even with this training,

2610-480: The vehicle to the ground. All the controls were analog circuits utilizing Burr-Brown transistor amplifier modules and other analog components. Two of the five vehicles survive: Aircraft of comparable role, configuration, and era Related lists Gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on

2668-418: The vehicle's roll axis. Gimbals are also used to mount everything from small camera lenses to large photographic telescopes. In portable photography equipment, single-axis gimbal heads are used in order to allow a balanced movement for camera and lenses. This proves useful in wildlife photography as well as in any other case where very long and heavy telephoto lenses are adopted: a gimbal head rotates

2726-465: The vehicle's rate of descent and horizontal movement. Sixteen smaller hydrogen peroxide thrusters, mounted in pairs, gave the pilot control in pitch, yaw and roll. The pilot had an ejection seat . On activation, it propelled the pilot upward from the vehicle with an acceleration of roughly 14 times the force of gravity for about a half second. From the ground, it was sufficient to propel the seat and pilot to an altitude of about 250 feet (80 m) where

2784-516: The vehicles' aerodynamic characteristics. After reviewing the results of the crash investigation, however, it was decided that the third LLTV (LLTV-3) be loaded into NASA's Super Guppy and flown to the Langley Research Center in Virginia for testing in its full-scale wind tunnel. Testing was initiated on January 7, 1968 and ended one month later on February 7. It was quickly determined that

2842-529: The walls. But to prevent the shipborne machinery from rolling around the deck in heavy seas, Athenaeus advises that "you must fix the pithêkion on the platform attached to the merchant-ships in the middle, so that the machine stays upright in any angle". After antiquity , gimbals remained widely known in the Near East . In the Latin West, reference to the device appeared again in the 9th century recipe book called

2900-506: The whole system with the lightest of touches on the gimbal. Powered by three brushless motors , motorized gimbals have the ability to keep the camera level on all axes as the camera operator moves the camera. An inertial measurement unit (IMU) responds to movement and utilizes its three separate motors to stabilize the camera. With the guidance of algorithms, the stabilizer is able to notice the difference between deliberate movement such as pans and tracking shots from unwanted shake. This allows

2958-586: The wind tunnel results, and on March 30 gave approval for the resumption of test flights in LLTV-2. The test program of 18 flights, all flown by H.E. Ream, was successfully completed on June 2. Hence, in the month before the Apollo 11 launch Armstrong was able to complete his LLTV flight training. He commented after his return: Eagle (the Lunar Module) flew very much like the Lunar Landing Training Vehicle which I had flown more than 30 times at Ellington Air Force Base near

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3016-551: Was a second generation vehicle, after the Lunar Landing Research Vehicle, used by NASA Apollo Program astronauts to develop piloting skills. The LLTV provided Apollo program commanders the opportunity to experience the flight characteristics associated with the 1/6 gravity conditions on the Moon. The first LLTV vehicle was assembled at Ellington Air Force Base in Houston, Texas in 1967. Three LLTV vehicles were eventually delivered to Ellington AFB. The last remaining of

3074-461: Was even able to correct for wind gusts within milliseconds, as they would have disturbed the impression of a missing atmosphere. FRC test pilot Don Mallick's comments following the vehicle's first flight in the lunar simulation mode illustrate the experience of piloting the LLRV: As a general statement concerning the translation ability on earth versus the translational ability in the lunar simulation;

3132-518: Was first described by the Greek inventor Philo of Byzantium (280–220 BC). Philo described an eight-sided ink pot with an opening on each side, which can be turned so that while any face is on top, a pen can be dipped and inked — yet the ink never runs out through the holes of the other sides. This was done by the suspension of the inkwell at the center, which was mounted on a series of concentric metal rings so that it remained stationary no matter which way

3190-417: Was kept pointing downward to Earth's center of mass regardless of the LLRV's attitude; this allowed the vehicle to tilt at the far greater angles that would be typical of hovering and maneuvering above the lunar surface. Despite its ungainly appearance, the LLRV was equipped with a highly sophisticated array of early sensors (mainly Doppler radar ) and computational hardware. The system had no specific name, but

3248-502: Was lost. The accident investigation board found that the fuel for the vehicle's attitude control thrusters had run out and that high winds were a major factor. As a result, JSC management decided to terminate further LLRV flights, as the first LLTV was about to be shipped from Bell to Ellington to begin ground and flight testing. LLRV-2 (NASA 951) was eventually returned to the Armstrong Flight Research Center , where it

3306-463: Was the first flight of the Lunar Module to the Moon, because NASA "didn't have plans to land on Apollo 10" so "there wasn't any point in ... training in the LLTV." Cernan only got this training after being assigned as backup commander for Apollo 14 , and in 1972 was the last to fly the LLTV while training as commander for Apollo 17 , the final landing mission. Built of aluminum alloy trusses ,

3364-450: Was the principal test pilot for its first flight in August 1968. Flight testing continued until December 8, when Algranti lost control of LLTV-1 during a flight to expand the vehicle's speed envelope. He managed to eject just three-fifths of a second before the vehicle hit the ground, the close call believed to be as a result of his attempt to regain control. The accident investigation found that

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