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Close Call

Forty-nine years ago this month, NASA Astronaut Neil A. Armstrong narrowly escaped with his life when he was forced to eject from the Lunar Landing Research Vehicle in which he was training. Armstrong punched-out only 200 feet above ground level and spent just 4 seconds in the silk before safely landing.

The Lunar Module (LM) was the vehicle used by Apollo astronauts to land on and depart from the lunar surface. This unique spacecraft consisted of separate descent and ascent rocket-powered stages. The powered descent phase was initiated at 50,000 feet AGL and continued all the way to landing. The powered ascent phase lasted from lunar lift-off to 60,000 feet AGL.

It was recognized early in the Apollo Program that landing a spacecraft on the lunar surface under vacuum conditions would be very challenging to say the least. To maximize their chances for doing so safely, Apollo astronauts would need piloting practice prior to a lunar landing mission. And they would need an earth-bound vehicle that flew like the LM to get that practice.

The Lunar Landing Research Vehicle (LLRV) was the answer to the above. The LLRV employed a turbojet engine that provided vertical thrust to cancel five-sixths of its weight since the gravity on the Moon is one-sixth that of Earth. The vehicle was also configured with dual lift rockets to provide vertical and horizontal motion. LLRV 3-axis attitude control was provided by a series of 16 small thrusters.

The LLRV was described by one historical NASA document as being “unconventional, contrary and ugly”. Known as the “Flying Bedstead”, the LLRV was designed for the specific purpose of simulating LM flight during the terminal phase of a lunar landing. The LLRV was not easy to fly in the “low and slow” flight regime in which it operated. The type was aesthetically unattractive in the extreme.

A pair of LLRV’s were constructed by Bell Aerosystems and flight tested at what is now the NASA Dryden Flight Research Center starting in October 1964. These vehicles were subsequently shipped to Ellington Air Force Base in Texas by early 1967. A number of flight crew, including Neil Armstrong, began LLRV flight training shortly thereafter.

Neil Armstrong made his first LLRV flight on Monday, 27 March 1967 in LLRV No. 1. (This occurred two months after the horrific Apollo 1 Fire.) Armstrong continued flight training in the LLRV over the next year in preparation for what would ultimately be the first manned lunar landing attempt in July of 1969

On Monday, 06 May 1968, Armstrong was flying LLRV No. 1 when the vehicle began losing altitude as its lift rockets lost thrust. Using turbojet power, Armstrong was able to get the LLRV to climb. As he did so, the vehicle made an uncommanded pitch-up and roll over. The attitude control system was unresponsive. The pilot had no choice but to eject.

Neil Armstrong ejected from the LLRV at 200 feet AGL as LLRV No. 1 crashed to destruction. The pilot was subjected to an acceleration of 14 G’s as his rocket-powered, vertically-seeking ejection seat functioned as designed. Armstrong got a full chute, but made only a few swings in same before safely touching-down back on terra firma. His only injury was to his tongue, which he accidently bit at the moment of ejection seat rocket motor ignition.

A mishap investigation board attributed the LLRV mishap to a design deficiency that allowed the helium gas pressurant of the lift rocket and attitude control system fuel tanks to be be accidently depleted. Thus, propellants could not be delivered to the lift rockets and attitude control system thrusters.

Neil Armstrong and indeed all of the Apollo astronauts who landed on the Moon trained in improved variants of the LLRV known as the Lunar Landing Training Vehicle (LLTV). This training was absolutely crucial to the success of the half-dozen Apollo crews who landed on the Moon. Indeed, there was no other way to adequately simulate moon landings except by flying the LLTV.

Posted in Aerospace, Final Flight, History

Rocket Man

Eighty-two years ago this month, pioneering rocket scientist Robert H. Goddard and staff fired a liquid-fueled rocket to a record altitude of 7,500 feet above ground level. The record-setting flight took place at Roswell, New Mexico.

Robert Hutchings Goddard was born in Worcester, Massachusetts on Thursday, 05 October 1882. He was enamored with flight, pyrotechnics, rockets and science fiction from an early age. By the time he was 17, Goddard knew that his life’s work would combine all of these interests.

Goddard was a sickly youth, but spent his well moments as a voracious reader of all manner of science-oriented literature. He graduated in 1904 from South High School in Worcester as the valedictorian of his class. He matriculated at Worcester Polytechnic and graduated with a Bachelor of Science degree in physics in 1908. A Master of Science degree and Ph.D. from Worcester’s Clark University followed in 1910 and 1911, respectively.

Goddard spent the next eight years of his life working on numerous propulsion and rocket-related projects. Then, in 1919, he published his now-famous scientific treatise entitled A Method of Reaching Extreme Altitudes. In that paper, the press glommed on to Goddard’s passing mention that a multi-staged rocket could conceivably fly all the way to the Moon.

Goddard was roundly ridiculed for his fanciful prognostications about Moon flight. The New York Times was especially derogatory in its estimation of Goddard’s ideas and accused him of junk science. A Times editorial even criticized Goddard for his ”misconception” that a rocket could produce thrust in the vacuum of space.

Even the U.S. government largely ignored Goddard. This scornful treatment to which Goddard was subject hurt him profoundly. So much so that he spent the remainder of his life alienated from the denizens of the press as well as the dolts of governmental employ.

Despite the blow to his professional reputation, Goddard resolutely pressed on with his rocket research. Indeed, after more that five years of intense development effort, Goddard and his staff launched the first liquid-fueled rocket on Tuesday, 16 March 1926 in Auburn, Massachusetts. The flight duration was short (2.5 seconds) and the peak altitude tiny (41 feet), but Goddard proved that liquid rocket propulsion was feasible.

Goddard’s liquid-fueled rocket testing would ultimately lead him from the countryside of New England to the desert of the Great South West. With financial support from Harry Guggenheim and the public backing of Charles Lindbergh, Goddard transfered his testing activities to Roswell, New Mexico in 1930. He would continue liquid-fueled rocket testing there until May 1941.

On Friday, 31 May 1935, experimental rocket flight A-8 took to the air from Goddard’s Roswell, New Mexico test site at 1430 UTC. Roughly 15 feet in length and weighing approximately 90 pounds at lift-off, the 9-inch diameter A-8 achieved a maximum altitude of 7,500 feet (1.23 nautical miles) above the desert floor. Only a flight in March of 1937 would go higher (9,000 feet).

Robert Goddard was ultimately credited with 214 U.S. patents for his rocket development work. Only 83 were awarded in his life time. His far-reaching inventions included rocket nozzle design, regenerativley cooled rocket engines, turbopumps, thrust vector controls, gyroscopic control systems and more.

Goddard died at the age of 62 from throat cancer in Baltimore, Maryland on Friday, 10 August 1945. Many years would pass before the full import of his accomplishments was comprehended. Then, the posthumously-bestowed recognition came in torrents. In 1959, Congress issued a special gold medal in Goddard’s honor. The Goddard Spaceflight Center was so named by NASA in 1959 as well. Many more such bestowals followed.

Perhaps the most meaningful of the recognitions ever accorded Robert Hutchings Goddard occurred 24 years after his passing. It was in connection with the first manned lunar landing in July of 1969. And it was poetic not only in terms of its substance and timing, but more particularly in light of the source from whence the recognition came.

A terse statement in the New York Times corrected a long-standing injustice. It read: “Further investigation and experimentation have confirmed the findings of Issac Newton in the 17th century, and it is now definitely established that a rocket can function in a vaccum as well as in an atmosphere. The Times regrets the error.”

Posted in Aerospace, History

Errant Arrow

Seventy years ago this month, a Hermes II experimental missile, launched on a flight test out of White Sands Proving Ground, strayed from the test range and impacted near Ciudad Juarez, Mexico. The non-fatal mishap was later attributed to a breakdown in basic range safety protocol.

The V2 missile (Vengeance Weapon No. 2) was developed by Nazi Germany during World War II for the purpose of attacking Allied population centers. As such, it was the world’s first ballistic missile. History records that more than 3,100 V2’s were fired in anger, with London, England and Antwerp, Belgium being the prime targets. Approximately 7,200 people lost their lives in V2 attacks between September 1944 and March 1945.

The V2 as flown by the Third Reich measured 46 feet in length and had a maximum diameter of 5.4 feet. Launch weight was 28,000 lbs. The V2’s rocket motor produced a maximum thrust of about 60,000 lbs at sea level. Ethyl alcohol and liquid oxygen served as fuel and oxidizer, respectively. Approximately 19,000 pounds of propellants were consumed in 65 seconds of boost flight.

The V2’s payload was an explosive warhead weighing about 1,600 lbs. The fearsome missile’s kinematic performance was impressive for its time. Maximum velocity was around 5,200 ft/sec. After burnout, the rocket followed a ballistic flight path all the way to the target. Maximum altitude and range for wartime missions was on the order of 50 nm and 175 nm, respectively.

With the defeat of Nazi Germany, both the United States and the Soviet Union gained access to a large number of V2 missiles and many of the German rocket scientists who developed the weapon. The United States shipped 300 rail freight cars full of V2 missile components back home. Under Operation Paperclip, some 126 German engineering and scientific personnel were expatriated to the United States. Initially operating out of Fort Bliss, Texas and White Sands Proving Ground (WSPG), New Mexico, these men were destined to make major contributions to the American space program. Among their number was one Werhner von Braun.

Sixty-seven V2 missiles were launched from White Sands Proving Ground (WSPG) between 1946 and 1952. These flights gave the United States invaluable experience in all aspects of rocket assembly, handling, fueling, launching and tracking. Indeed, V2 rocket technology and lessons-learned were applied in the development of all subsequent American launch vehicles ranging from the Redstone to the Saturn V. WSPG V2’s were also used to conduct numerous high altitude and space research experiments. Many aerospace “firsts” were achieved along the way. The first biological space payloads, first photographs of earth from space and the first large two-stage rocket flights involved the former vengeance weapon.

Rocket system reliability was not particularly good in the 1940’s and 1950’s. For instance, only 68% of the WSPG V2 flights were considered successful. Range safety was in its infancy too. In particular, the comprehensive range safety protocol that governs flight operations at today’s test ranges did not yet exist. This state of affairs was largely due to the fact that much of the systems knowledge and operations lessons-learned required to establish such a protocol had yet to be acquired. An incident that occurred in May of 1947 serves to underscore the reliability and safety issues just noted.

The Hermes II missile (RTV-G-3/RV-A-3) was a derivative of the basic V2 vehicle. The payload was a forward-mounted, winged, ramjet engine test bed. The V2’s tail surfaces were enlarged to counter the destabilizing influence of the payload’s wing group. The idea was to get the payload up to a Mach number beyond 3 and separate it from the V2 booster. Following separation, the ramjet pack would be ignited and thrust established. The payload would then fly a programmed altitude-Mach number flight profile. While ambitious on several levels, the project was certainly emblematic of this era of aerospace history wherein all manner of ideas took to the skies.

On Thursday, 29 May 1947, Hermes II was fired from Launch Complex 33 at White Sands Proving Ground. It was approximately 1930 hours local time. It is noted that the ramjet pack was not active for this first flight. The Hermes test vehicle was supposed to pitch to the north and fly uprange. Instead, it pitched to the south and backrange toward El Paso, Texas. Post-flight analysis revealed that the new inertial guidance system employed by the Hermes missile had been wired backwards! This human error directly and adversely affected rocket system reliability.

The WSPG Range Safety Officer(RSO) had both the authority and responsibility to hit the destruct button once it was obvious that the Hermes II was errant. However, a project scientist physically restrained the RSO from doing so! Apparently, the scientist was of the (evidently strong) opinion that the test vehicle’s propellant load should not be wasted on such trivial grounds as the safety of the El Paso populace. Unimpeded now, the errant rocket continued its flight. Range safety protocol would have to be improved and understood by all participants prior to the next flight!

The Hermes II reached a maximum altitude of 35 nm on its unplanned trip to the south. During its 5 -minute flight, the vehicle overflew the city of El Paso and impacted near the Tepeyac Cemetery located 3.5 miles south of Ciudad Juarez, Mexico. The quasi-Mach 1 impact formed a crater that measured 50 feet in width and 24 feet in depth. Enterprising local residents gathered what little airframe wreckage that survived impact and sold it to souvenir seekers!

United States Army authorities quickly arrived on scene to ascertain the extent of the damage caused by the errant missile’s unannounced and unwelcome arrival. Happily, no lives were lost. Profuse apologies were delivered to and graciously accepted by Mexican government officials. The United States paid for all damages and effected a complete clean-up and remediation of the impact site.

A member of the team of expatriated German scientists who conducted the Hermes II flight test later was quoted as saying: “We were the first German unit to not only infiltrate the United States, but to attack Mexico from US soil!” Not nearly so amused, the Army tightened-up range safety protocol at WSPG in the aftermath of the international incident. Interestingly, historical evidence points to the likelihood that the Hermes II vehicle never did carry an active ramjet payload on test flights out of WSPG.

Posted in Aerospace, History

The Flight of Freedom 7

Fifty-six years ago this week, United States Navy Commander Alan Bartlett Shepard, Jr. became the first American to be launched into space. Shepard named his Mercury spacecraft Freedom 7.

Officially designated as Mercury-Redstone 3 (MR-3) by NASA, the mission was America’s first true attempt to put a man into space. MR-3 was a sub-orbital flight. This meant that the spacecraft would travel along an arcing parabolic flight path having a high point of about 115 nautical miles and a total range of roughly 300 nautical miles. Total flight time would be about 15 minutes.

The Mercury spacecraft was designed to accommodate a single crew member. With a length of 9.5 feet and a base diameter of 6.5 feet, the vehicle was less than commodious. The fit was so tight that it would not be inaccurate to say that the astronaut wore the vehicle. Suffice it to say that a claustrophobic would not enjoy a trip into space aboard the spacecraft.

Despite its diminutive size, the 2,500-pound Mercury spacecraft (or capsule as it came to be referred to) was a marvel of aerospace engineering. It had all the systems required of a space-faring craft. Key among these were flight attitude, electrical power, communications, environmental control, reaction control, retro-fire package, and recovery systems.

The Redstone booster was an Intermediate Range Ballistic Missile (IRBM) modified for the manned mission. The Redstone’s uprated A-7 rocket engine generated 78,000 pounds of thrust at sea level. Alcohol and liquid oxygen served as propellants. The Mercury-Redstone combination stood 83 feet in length and weighed 66,000 pounds at lift-off.

On Friday, 05 May 1961, MR-3 lifted-off from Cape Canaveral’s Launch Complex 5 at 14:34:13 UTC. Alan Shepard went to work quickly calling out various spacecraft parameters and mission events. The astronaut would experience a maximum acceleration of 6.5 g’s on the ride upstairs.

Nearing apogee, Shepard manually controlled Freedom 7 in all 3 axes. In doing so, he positioned the capsule in the required 34-degree nose-down attitude. Retro-fire occurred on-time and the retro package was jettisoned without incident. Shepard then pitched the spacecraft nose to 14 degrees above the horizon preparatory to reentry into the earth’s atmosphere.

Reentry forces quickly built-up on the plunge back into the atmosphere with Shepard enduring a maximum deceleration of 11.6 g’s. He had trained for more than 12 g’s prior to flight. At 21,000 feet, a 6-foot droghue chute was deployed followed by the 63-foot main chute at 10,000 feet. Freedom 7 splashed-down in the Atlantic Ocean 15 minutes and 28 seconds after lift-off.

Following splashdown, Shepard egressed Freedom 7 and was retreived from the ocean’s surface by a recovery helicopter. Both he and Freedom 7 were safely onboard the carrier USS Lake Champlain within 11 minutes of landing. During his brief flight, Shepard had reached a maximum speed of 5,180 mph, flown as high as 116.5 nautical miles and traveled 302 nautical miles downrange.

The flight of Freedom 7 had much the same effect on the Nation as did Lindbergh’s solo crossing of the Atlantic in 1927. However, in light of the Cold War fight against the world-wide spread of Soviet communism, Shepard’s flight was arguably more important. Indeed, Alan Shepard became the first of what Tom Wolfe called in his classic book The Right Stuff, the American single combat warrior.

For his heroic MR-3 efforts, Alan Shepard was awarded the Distinguished Service Medal by an appreciative nation. In February 1971, Alan Shepard walked on the surface of the Moon as Commander of Apollo 14. He was the lone member of the original Mercury Seven astronauts to do so. Shepard was awarded the Congressional Space Medal of Freedom in 1978.

Alan Shepard succumbed to leukemia in July of 1998 at the age of 74. In tribute to this American space hero, naval aviator and US Naval Academy graduate, Alan Shepard’s Freedom 7 spacecraft now resides in a place of honor at the United States Naval Academy in Annapolis, Maryland.

Posted in Aerospace, History

Mercury Seven Astronauts

Fifty-eight years ago this month, NASA held a press conference in Washington, D.C. to introduce the seven men selected to be Project Mercury Astronauts. They would become known as the Mercury Seven or Original Seven.

Project Mercury was America’s first manned spaceflight program. The overall objective of Project Mercury was to place a manned spacecraft in Earth orbit and bring both man and machine safely home. Project Mercury ran from 1959 to 1963.

The men who would ultimately become Mercury Astronauts were among a group of 508 military test pilots originally considered by NASA for the new role of astronaut. The group of 508 candidates was then successively pared to 110, then 69 and finally to 32. These 32 volunteers were then subjected to exhaustive medical and psychological testing.

A total of 18 men were still under consideration for the astronaut role at the conclusion of the demanding test period. Now came the hard part for NASA. Each of the 18 finalists was truly outstanding and would be a worthy finalist. But there were only 7 spots on the team.

On Thursday, 09 April 1959, NASA publicly introduced the Mercury Seven in a special press conference held for this purpose at the Dolley Madison House in Washington, D.C. The men introduced to the Nation that day will forever hold the distinction of being the first official group of American astronauts. In the order in which they flew, the Mercury Seven were:

Alan Bartlett Shepard Jr., United States Navy. Shepard flew the first Mercury sub-orbital mission (MR-3) on Friday, 05 May 1961. He was also the only Mercury astronaut to walk on the Moon. Shepherd did so as Commander of Apollo 14 (AS-509) in February 1971. Alan Shepard succumbed to leukemia on 21 July 1998 at the age of 74.

Vigil Ivan Grissom, United States Air Force. Grissom flew the second Mercury sub-orbital mission (MR-4) on Friday, 21 July 1961. He was also Commander of the first Gemini mission (GT-3) in March 1965. Gus Grissom might very well have been the first man to walk on the Moon. But he died in the Apollo 1 Fire, along with Astronauts Edward H. White II and Roger Chaffee, on Friday, 27 January 1967. Gus Grissom was 40 at the time of his death.

John Herschel Glenn Jr., United States Marines. Glenn was the first American to orbit the Earth (MA-6) on Thursday, 22 February 1962. He was also the only Mercury Astronaut to fly a Space Shuttle mission. He did so as a member of the STS-95 crew in October of 1998. Glenn was 77 at the time and still holds the distinction of being the oldest person to fly in space. John Glenn was the last member of the Mercury Seven to depart this earth when he passed away in December 2016 at the age of 95.

Malcolm Scott Carpenter, United States Navy. Carpenter became the second American to orbit the Earth (MA-7) on Thursday, 24 May 1962. This was his only mission in space. Carpenter subsequently turned his attention to under-sea exploration and was an aquanaut on the United States Navy SEALAB II project. Scott Carpenter died in October 2013 shortly after suffering a stroke. He was 88 at the time of his passing.

Walter Marty Schirra Jr., United States Navy. Schirra became the third American to orbit the Earth (MA-8) on Wednesday, 03 October 1962. He later served as Commander of Gemini 6A (GT-6) in December 1965 and Apollo 7 (AS-205) in October 1968. Schirra was the only Mercury Astronaut to fly Mercury, Gemini and Apollo space missions. Wally Schirra died from a heart attack in May 2007 at the age of 84.

Leroy Gordon Cooper Jr., United States Air Force. Cooper became the fourth American to orbit the Earth (MA-9) on Wednesday, 15 May 1963. In doing so, he flew the last and longest Mercury mission (22 orbits, 34 hours). Cooper was also Commander of Gemini 5 (GT-5), the first long-duration Gemini mission, in August 1965. Gordo Cooper died from heart failure in October 2004 at the age of 77.

Donald Kent Slayton, United States Air Force. Slayton was the only Mercury Astronaut to not fly a Mercury mission when he was grounded for heart arrythemia in 1962. He subsequently served many years on Gemini and Apollo as head of astronaut selection. He finally got his chance for spaceflight in July 1975 as a crew member of the Apollo-Soyuz mission (ASTP). Deke Slayton died from brain cancer in June of 1993 at the age of 69.

History records that the Mercury Seven was the only group of NASA astronauts that had a member that flew each of America’s manned spacecraft (i.e, Mercury, Gemini, Apollo and Shuttle). Though just men and imperfect mortals, we honor and remember them for their genuinely heroic deeds and unique contributions made to the advancement of American manned spaceflight.

Posted in Aerospace, History

NASA’s Finest Hour

Forty-six years ago this month, the crew of Apollo 13 departed Earth and headed for the Fra Mauro highlands of the Moon. Less than six days later, they would be back on Earth following an epic life and death struggle to survive the effects of an explosion that rocked their spacecraft 200,000 miles from home.

Apollo 13 was slated as the 3rd lunar landing mission of the Apollo Program. The intended landing site was the mountainous Fra Mauro region near the lunar equator. The Apollo 13 crew consisted of Commander James A. Lovell, Jr., Lunar Module Pilot Fred W. Haise, Jr. and Command Module Pilot John L. (Jack) Swigert, Jr. Lovell was making his fourth spaceflight (second to the Moon) while Haise and Swigert were space rookies.

Apollo 13 lifted-off from LC-39A at Cape Canaveral, Florida on Saturday, 11 April 1970. The official launch time was 19:13:00 UTC (13:13 CST). During second stage burn, the center engine shutdown two minutes early as a result of excessive longitudinal structural vibrations. The outer four J-2 engines burned 34 seconds longer to compensate. Arriving safely in low Earth orbit, Lovell observed that every mission seemed to have at least one major glitch. Clearly, Apollo 13′s was now out of the way!

The Apollo 13 payload stack consisted of a Command Module (CM), Service Module (SM) and Lunar Module (LM). The entire ensemble had a lift-off mass of nearly 49 tons. In keeping with tradition, the Apollo 13 crew gave call signs to their Command Module and Lunar Modules. This helped flight controllers distinguish one vehicle from the other over the communications net during mission operations. The CM was named Odyssey and the LM was given the name of Aquarius.

The first two days of the outward journey to the Moon were uneventful. In fact, some at Mission Control in Houston, Texas seemed somewhat bored. The same could be said for the ever-astute press corps who predictably reported that Americans were now responding to the lunar landing missions with a collective yawn. The journalistic sages averred that the space program needed some pepping-up. Going to the Moon might have been impossible yesterday, but today its just run-of-the-mill stuff. Actually, it was all kind of easy. So wrote they of the fickle Fourth Estate.

It all started with a bang at 03:07:53 UTC on Tuesday, 14 April 1970 (21:07:53 CST, 13 April 1970) with Apollo 13 distanced 200,000 miles from Earth. “Houston, we’ve had a problem here.” This terse statement from Jack Swigert informed Mission Control that something ominous had just occurred onboard Apollo 13. Jim Lovell reported that the problem was a “Main B Bus undervolt”. A potentially serious electrical system problem.

But what was the exact nature of the of problem and why did it occur? Nary a soul in the spacecraft nor in Mission Control could provide the answers. All anyone really knew at the moment was that two of three fuel cells formerly supplying electricity to the Command Module were now dead. Arguably more alarming, Oxygen Tank No. 2 was empty with Tank No. 1 losing oxygen at a high rate.

There was something else. The Apollo 13 reaction control system was firing in apparent response to some perturbing influence. But what was it? The answer came with all the subtlety of a sledge hammer blow. Jim Lovell reported that some kind of gas was venting from the spacecraft into space. That chilling observation suddenly explained why the No. 1 oxygen tank was losing pressure so rapidly.

Once Mission Control and the Apollo 13 astronauts fully comprehended the gravity of the situation, the entire team went to work to bring the spacecraft home. Odyssey was powered-down to conserve its battery power for reentry while Aquarius was powered-up and became a makeshift lifeboat. A major problem was that Aquarius had battery power and water sufficient for only 40 hours of flight. The trip home would take 90 hours.

Amazingly, engineering teams at Mission Control conceived and tested means to minimize electrical usage onboard Aquarius. However, the Apollo 13 crew would have to endure privation and hardships to survive. The cabin temperature in Aquarius got down to 38F and each man was permitted only six ounces of water per day. The walls of the spacecraft were covered with condensation. Sleep was almost impossible and fatigue became another unrelentless enemy to survival.

And then there was the build-up of carbon dioxide. The LM environmental system (EV) was designed to support two men. Now there were three. Between the CM and LM, there was an ample supply of lithium hydroxide canisters to scrub the gas from the cabin atmosphere for the trip home. However, the square CM canisters were incompatible with the circular openings on LM EV. The engineers on the ground invented a device to eliminate this compatibility using materials found onboard the spacecraft.

The Apollo 13 crew had to fire the LM descent motor several times in order to adjust their return trajectory. Use of the SM propulsion system to effect these firings was denied the crew due to concerns that the explosion could have damaged it. These rocket motor firings required precise inertial navigation. The star sightings required for celestial navigation were impossible to make owing to the huge cloud of debris surrounding the spacecraft. Means were devised to use the Sun as the primary navigational source.

While the nation and indeed the world looked on, the miracle of Apollo 13 slowly unfolded. Many a humble heart uttered a prayer for and in behalf of the trio of astronauts. Millions throughout the world followed the men’s journey home via newspaper, radio, television and other media.

As Apollo 13 approached the Earth, the overriding issue was whether the systems onboard Odyssey could be successfully brought back on line. The walls and instrument panels of the craft were drenched with condensation. Unquestionably, the electronics and wiring bundles behind those instrument panels were also soaking wet. Would they short-out once electrical energy flowed through them again? Would there be enough battery power for reentry?

Happily, the CM power-up sequence was successfully accomplished. Once again the resourceful engineers at Mission Control produced under extreme duress. They devised an intricate and never-attempted-in-flight power-up sequence for the CM. Too, the extra insulation added to the CM’s electrical system in the aftermath of the Apollo 1 fire provided protection from condensation-induced electrical arcing.

Approximately four hours prior to reentry, the Apollo 13 crew jettisoned the SM. What they saw was shocking. The module was missing a complete external panel and most of the equipment inside was gone or significantly damaged. One hour prior to entry, Aquarius, their trusty space lifeboat, was also jettisoned. The only concern now was whether the Command Module base heatshield had survived the explosion intact.

On Friday, 17 April 1970, Odyssey hit entry interface (400,000 feet) at 36,000 feet per second. Other than a worrisome additional 33 seconds of plasma-induced communications blackout (4 minutes, 33 seconds total), the reentry was entirely nominal. Splashdown occurred at 18:07:41 UTC near American Samoa in the Pacific Ocean. The USS Iwo Jima quickly recovered spacecraft and crew.

The post-flight mishap investigation revealed that Oxygen Tank No. 2, located deep within the bowels of the SM, exploded when the crew conducted a cryo-stir of its multi-phase contents. Unknown to all was the fact that a mismatch between the tank heater and thermostat had resulted in the Teflon insulation of the internal wiring being severely damaged during previous ground operations. This meant that the tank was now a bomb and would detonate its contents when used the next time. In this case, the next time was in flight. The warning signs were there, but went unheeded.

Apollo 13 never landed at Fra Mauro. And none of its crew would ever again fly in space. But in many ways, Apollo 13 was NASA’s finest hour. Overcoming myriad seemingly intractable obstacles in the aftermath of a completely unanticipated catastrophe, deep in trans-lunar space, will forever rank high among the legendary accomplishments of spaceflight. With essentially no margin for error and in the harsh glare of public scrutiny, NASA wrested victory from the tentacles of almost certain failure and brought three weary men safely back to their home planet.

Posted in Aerospace, History

Hail, Columbia!

Thirty-six years ago today, the United States successfully launched the Space Shuttle Columbia into orbit around the Earth. It was the maiden flight of the Nation’s Space Transportation System (STS).

The Space Shuttle was unlike any manned space vehicle ever flown. A giant aircraft known as the Orbiter was side-mounted on a huge liquid-propellant stage called the External Tank (ET). Flanking opposing sides of the ET was a pair of Solid Rocket Boosters (SRB). The Orbiter, SRB’s and ET measured 122 feet, 149 feet and 154 feet in length, respectively.

The Space Shuttle system was conceived with an emphasis on reusability. Each Orbiter (Columbia, Challenger, Atlantis, Discovery, and Endeavor) was designed to fly 100 missions. Each SRB was intended for multiple mission use as well. The only single-use element was the ET since it was more cost effective to use a new one for each flight than to recover and refurbish a reusable version.

NASA called STS-1 the boldest test flight in history. Indeed, the STS-1 mission marked the first time that astronauts would fly a space vehicle on its inaugural flight! STS-1 was also the first time that a manned booster system incorporated solid rocket propulsion. Unlike liquid propellant rocket systems, once ignited, the Shuttle’s solid rockets burned until fuel exhaustion.

And then there was the Orbiter element which had its own new and flight-unproven propulsion systems. Namely, the Space Shuttle Main Engines (SSME) and Orbital Maneuvering System (OMS). Each of the three (3) SSME’s generated 375,000 pounds of thrust at sea level. Thrust would increase to 475,000 pounds in vacuum. Each OMS rocket engine produced 6,000 pounds of thrust in vacuum.

The Orbiter was also configured with a reusable thermal protection system (TPS) which consisted of silica tiles and reinforced carbon-carbon material. The TPS for all previous manned space vehicles utilized single-use ablators. Would the new TPS work? How robust would it be in flight? What post-flight care would be needed? Answers would come only through flight.

To add to the “excitement” of first flight, the Orbiter was a winged vehicle and would therefore perform a hypersonic lifting entry. The vehicle energy state would have to be managed perfectly over the 5,000 mile reentry flight path from entry interface to runway touchdown. Since the Orbiter flew an unpowered entry, it would land dead-stick. There would only be one chance to land.

On Sunday,12 April 1981, the Space Shuttle Columbia lifted-off from Pad 39A at Cape Canaveral, Florida. Official launch time was 12:00:03 UTC. The flight crew consisted of Commander John W. Young and Pilot Robert L. Crippen. Their Columbia launch stack tipped the scales at 4.5 million pounds and thundered away from the pad on over 7 million pounds of thrust.

Columbia went through maximum dynamic pressure (606 psf) at Mach 1.06 and 26.5 KFT. SRB separation occurred 120 seconds into flight at Mach 3.88 and 174,000 feet; 10,000 feet higher than predicted. This lofting of the ascent trajectory was later attributed to unmodeled plume-induced aerodynamic effects in the Orbiter and ET base region.

Following separation, Columbia rode the ET to burnout at Mach 21 and 389.7 KFT. Following ET separation, Columbia’s OMS engines were fired minutes later to achieve a velocity of 17,500 mph and a 166-nautical mile orbit.

Young and Crippen would orbit the Earth 37 times before coming home on Tuesday, 14 April 1981. In doing so, they successfully flew the first hypersonic lifting reentry from orbit. Though unaware of it at the time, the crew came very close to catastrophe as the Orbiter’s body flap had to be deflected 8 degrees more than predicted to maintain hypersonic pitch control.

The reason for this “hypersonic anomaly” was that ground test and aero modeling had failed to capture the effects of high temperature gas dynamics on Orbiter pitch aerodynamics. Specifically, the vehicle was more stable in hypersonic flight than had been predicted. This necessitated greater nose-down body flap deflections to trim the vehicle in pitch. It was a close-call. But Columbia and her crew lived to fly another day.

Columbia touched-down at 220 mph on Runway 23 at Edwards Air Force Base, California at 18:20:57 UTC. Young and Crippen were euphoric with the against-the-odds success of the Space Shuttle’s first mission.

NASA too reveled in the Shuttle’s accomplishment. And so did America. This was the country’s first manned space mission since 1975. The longest period of manned spaceflight inactivity ever in the Nation’s history.

Fittingly, a well-known national news magazine celebrated Columbia’s success with a headline which read: “America is Back!”

And while Columbia nor any of its stablemates fly no more, we remember with fondness that first Orbiter, its first flight, and its many subsequent accomplishments. To which we say: Hail Columbia!

Posted in Aerospace, History

USAF/Convair XB-46

Seventy years ago this week, the USAF/Convair XB-46 took to the skies on its maiden flight. Convair test pilot Ellis D. “Sam” Shannon was at the controls of the sleek, multi-jet prototype medium range bomber.

The XB-46 was a product of the flurry of aircraft design-build-and-fly activity that gripped the American aviation industry in the second half of the 1940’s. While most never saw the production line, all manner of new and innovative aircraft design concepts were built and flown by aircraft companies.

The XB-46 was a contemporary of and competitor with other jet-powered bomber concepts such as the North American XB-45 Tornado, North American XB-47 Stratojet, and Martin XB-48. With an unrefueled range of 2,500 nm and a service ceiling of 40,000 feet, the XB-46 was designed to carry a bomb load of 22,000 lbs.

The big bomber measured 105.75 feet in length and had a wingspan of 113 feet. Power was provided by a quartet of J35 turbojets which delivered 16,000 lbs of sea level thrust. The type’s gross take-off and empty weights were 95,000 lbs and 48,000 lbs, respectively.

The XB-46’s air crew consisted of a pilot and co-pilot who sat in tandem as well as a third crew member who was situated in the nose. This latter individual was a real jack-of-all-trades who served as the bombardier, navigator, and radio operator.

The one and only XB-46 aircraft (S/N 45-59582) departed on its first flight from Convair’s Lindbergh Field in San Diego on Wednesday, 02 April 1947. Pilot Sam Shannon headed north to Muroc Army Air Field where he safely landed an hour and a half later following an uneventful flight.

By the end of September 1947, the lone XB-46 aircraft had made 64 flights and spent 127 hours in the air. While the aircraft was found to have excellent stability and control characteristics and favorable handling qualities, the rapid pace of aeronautical progress quickly rendered it obsolete.

Although the XB-46 project was cancelled in August 1947, the airplane was transferred to Florida’s Palm Beach Air Force Base for additional flight testing. Researchers focused primarily on airframe structural and vibrational issues during the 44 hours of flight testing that took place from August 1948 to August 1949.

Although a worthy design concept that flew well, the XB-46 was eclipsed by a better airplane. In this case, the legendary USAF/Boeing B-47 Stratojet. But such was the fate of many post-WWII aircraft projects that vied for military production contracts during the fifth and sixth decades of the twentieth century.

The XB-46 exhibited a certain majesty in flight that was emblematic of the early jet age. Its development helped to improve the art of designing and flying large aircraft. As such, it would be nice to see it displayed in a prominent aviation museum. Regrettably, the single XB-46 prototype airframe was scrapped in the early 1950’s and no longer exists.

Posted in Aerospace, History

HYPER-X Flight II: Making History

Thirteen years ago today, the NASA X-43A scramjet-powered flight research vehicle reached a record speed of over 4,600 mph (Mach 6.83). The test marked the first time in the annals of aviation that a flight-scale scramjet accelerated an aircraft in the hypersonic Mach number regime.

NASA initiated a technology demonstration program known as HYPER-X in 1996. The fundamental goal of the HYPER-X Program was to successfully demonstrate sustained supersonic combustion and thrust production of a flight-scale scramjet propulsion system at speeds up to Mach 10.

The scramjet is a key to sustained hypersonic flight within the earth’s atmosphere. Whereas rockets are capable of producing large thrust magnitudes, the amount of thrust per unit propellant mass is low. In part, this is because a rocket has to carry its own fuel and oxidizer. A scramjet is a much more efficient producer of thrust in that it only has to carry its fuel and uses the atmosphere as its oxidizer source.

Rocket technology is a highly developed discipline with a deep experience and application base. In contradistinction, flight-scale scramjet technology is still in a developmental stage. Considerations such as initiating and sustaining stable combustion is a supersonic stream, efficient conversion of fuel chemical energy to kinetic energy, and optimal integration of the scramjet propulsion system into a hypersonic airframe are among the challenges that face designers.

Also known as the HYPER-X Research Vehicle (HXRV), the X-43A aircraft was a scramjet test bed. The aircraft measured 12 feet in length, 5 feet in width, and weighed nearly 3,000 pounds. The X-43A was boosted to scramjet take-over speeds with a modified Orbital Sciences Pegasus rocket booster.

The combined HXRV-Pegasus stack was referred to as the HYPER-X Launch Vehicle (HXLV). Measuring approximately 50 feet in length, the HXLV weighed slightly more than 41,000 pounds. The HXLV was air-launched from a B-52 mothership. Together, the entire assemblage constituted a 3-stage vehicle.

The second flight of the HYPER-X program took place on Saturday, 27 March 2004. The flight originated from Edwards Air Force Base, California. Using Runway 04, NASA’s venerable B-52B (S/N 52-0008) started its take-off roll at approximately 20:40 UTC. The aircraft then headed for the Pacific Ocean launch point located just west of San Nicholas Island.

At 21:59:58 UTC, the HXLV fell away from the B-52B mothership. Following a 5 second free fall, rocket motor ignition occurred and the HXLV initiated a pull-up to start its climb and acceleration to the test window. It took the HXLV about 90 seconds to reach a speed of slightly over Mach 7.

Following rocket motor burnout and a brief coast period, the HXRV (X-43A) successfully separated from the Pegasus booster at 94,069feet and Mach 6.95. The HXRV scramjet was operative by Mach 6.83. Supersonic combustion and thrust production were successfully achieved. Total power-on flight duration was approximately 11 seconds.

As the X-43A decelerated along its post-burn descent flight path, the aircraft performed a series of data gathering flight maneuvers. A vast quantity of high-quality aerodynamic and flight control system data were acquired for Mach numbers ranging from hypersonic to transonic. Finally, the X-43A impacted the Pacific Ocean at a point about 450 nautical miles due west of its launch location. Total flight time was approximately 15 minutes.

The HYPER-X Program made history that day in late March 2004. Supersonic combustion and thrust production of an airframe-integrated scramjet were achieved for the first time in flight; a goal that dated back to before the X-15 Program. Along the way, the X-43A established a speed record for airbreathing aircraft and earned a Guinness World Record for its efforts.

Posted in Aerospace, History

XB-45 Tornado First Flight

Seventy years ago this month, the USAF/North American XB-45 Tornado bomber made its inaugural test flight at Muroc Army Air Field, California. The type would go on to become the United States’ first operational turbojet-powered bomber.

The XB-45 measured 74 feet in length, had a wingspan of 89.5 feet and a GTOW of 82,000 lbs. Power was provided by a quartet of Allison J35-A-7 turbojets producing a rather paltry 16,000 lbs of sea level thrust. With a maximum speed at sea level of roughly 500 mph, the service ceiling of the XB-45 was 37,600 feet.

A trio of XB-45 prototype aircraft were manufactured for the Air Force by North American. Serial numbers 45-59479, 45-59480, and 45-59481 were assigned to the three ships. Air crew consisted of two pilots who sat in tandem. The XB-45 flight test program included slightly more than 130 flights.

The first flight of the XB-45, Ship No. 1 (S/N 45-59479) took place on Monday, 17 March 1947 at Muroc Army Air Field, California. North American test pilot George W. Krebs was in the cockpit of the prototype bomber. The one-hour test hop was restricted to low speeds because the landing gear doors could not be fully closed.

Production versions of the Tornado included the B-45A, B-45C, and RB-45C. These aircraft were powered by General Electric J-47 turbojets and represented a great improvement relative to the XB-45 in terms of performance, operability, and reliability. Aircrew for the production Tornado variants included a pilot, co-pilot, bombardier-navigator, and tail gunner.

The Royal Air Force (RAF) used the RB-45C to fly clandestine recon missions over the Soviet Union between 1952 and 1954. Known as Operation Ju-jitsu, RB-45C aircrews gathered electronic and photographic intelligence information critical to the Free World’s defense posture. These high-risk RB-54C missions ultimately led to development of more capable recon aircraft; the Lockheed U-2 and SR-71.

The B-45 and RB-45 Tornado served in the Strategic Air Command (SAC) from 1950 through 1959. The B-45A holds the distinction of being USAF’s first operational jet-powered bomber as well as the first multi-jet bomber to be air-refueled. It was also the first jet bomber to carry and drop a nuclear weapon.

Posted in Aerospace, History
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