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Grapefruit Satellite

Sixty-one years ago this week, the United States Navy Vanguard Program registered its first success with the orbiting of the Vanguard 1 satellite. The diminutive orb was the fourth man-made object to be placed in Earth orbit.

The Vanguard Program was established in 1955 as part of the United States involvement in the upcoming International Geophysical Year (IGY). Spanning the period between 01 July 1957 and 31 December 1958, the IGY would serve to enhance the technical interchange between the east and west during the height of the Cold War.

The overriding goal of the Vanguard Program was to orbit the world’s first satellite sometime during the IGY. The satellite was to be tracked to verify that it achieved orbit and to quantify the associated orbital parameters. A scientific experiment was to be conducted using the orbiting asset as well.

Vanguard was managed by the Naval Research Laboratory (NRL) and funded by the National Science Foundation (NSF). This gave the Vanguard Program a distinctly scientific (rather than military) look and feel. Something that the Eisenhower Administration definitely wanted to project given the level of Cold War tensions.

The key elements of Vanguard were the Vanguard launch vehicle and the Vanguard satellite. The Vanguard 3-stage launch vehicle, manufactured by the Martin Company, evolved from the Navy’s successful Viking sounding rocket. The Vanguard satellite was developed by the NRL.

On Friday, 04 October 1957, the Soviet Union orbited the world’s first satellite – Sputnik I. While the world was merely stunned, the United States was quite shocked by this achievement. A hue and cry went out across the land. How could this have happened? Will the Soviets now unleash nuclear weapons on us from space? And most hauntingly – where is our satellite?

In the midst of scrambling to deal with the Soviet’s space achievement, America would receive another blow to the national solar plexus on Sunday, 03 November 1957. That is the day that the Soviet Union orbited their second satellite – Sputnik II. And this one even had an occupant onboard; a mongrel dog name Laika.

The Vanguard Program was now uncomfortably in the spotlight. But it really wasn’t ready at that moment to be America’s response to the Soviets. After all, Vanguard was just a research program. While the launch vehicle was developing well enough, it certainly was not ready for prime time. The Vanguard satellite was a new creation and had never been used in space.

History records that the first American satellite launch attempt on Friday, 06 December 1957 went very badly. The launch vehicle lost thrust at the dizzying height of 4 feet above the pad, exploded when it settled back to Earth whereupon it consumed itself in the resulting inferno. Amazingly, the Vanguard satellite survived and was found intact at the edge of the launch pad.

Faced with a quickly deteriorating situation, America desperately turned to the United States Army for help. Wernher von Braun and his team at the Army Ballistic Missile Agency (ABMA) responded by orbiting Explorer I on Friday, 31 January 1958. America was now in space!

The Vanguard Program regrouped and attempted to orbit a Vanguard satellite on Wednesday, 05 February 1958. Fifty-seven seconds into flight the launch vehicle exploded. Vanguard was now 0 for 2 in the satellite launching business. Undeterred, another attempt was scheduled for March.

Monday, 17 March 1958 was a good day for the Vanguard Program and the United States of America. At 12:51 UTC, Vanguard launch vehicle TV-4 departed LC-18A at Cape Canaveral, Florida and placed the Vanguard 1 satellite into a 2,466-mile x 406-mile elliptical orbit. On this Saint Patrick’s Day, Vanguard registered its first success and America had a second satellite orbiting the Earth.

Whereas the Soviet satellites weighed hundreds of pounds, Vanguard 1 was tiny. It was 6.4-inches in diameter and weighed only 3.25 pounds. Soviet Premier Nikita Khrushchev mockingly referred to it as America’s “grapefruit satellite”. Small maybe, but mighty as well. Vanguard 1 went on to record many discoveries that helped write the book on spaceflight.

Khrushchev is gone and all of those big Sputniks were long ago incinerated in the fire of reentry. Interestingly, the “grapefruit satellite” is still in space. Indeed, it is the oldest satellite in Earth orbit. As of this writing, Vanguard 1 has completed over 200,000 Earth revolutions and traveled more than 5.7 billion nautical miles since 1958. It is expected to stay in orbit for another 240 years. Not too bad for a grapefruit.

Posted in Aerospace, History

Emergency in Earth Orbit

Fifty-three years ago this month, the crew of Gemini VIII successfully regained control of their tumbling spacecraft following failure of an attitude control thruster. The incident marked the first life-threatening on-orbit emergency and resulting mission abort in the history of American manned spaceflight.

Gemini VIII was the sixth manned mission of the Gemini Program. The primary mission objective was to rendezvous and dock with an orbiting Agena Target Vehicle (ATV). Successful accomplishment of this objective was seen as a vital step in the Nation’s quest for landing men on the Moon.

The Gemini VIII crew consisted of Command Pilot Neil A. Armstrong and Pilot USAF Major David R. Scott. Both were space rookies. To them would go both the honor of achieving the first successful docking in orbit as well as the challenge of dealing with the first life and death space emergency involving an American spacecraft.

Gemini VIII lifted-off from Cape Canaveral’s LC-19 at 16:41:02 UTC on Wednesday, 16 March 1966. The crew’s job was to chase, rendezvous and then physically dock with an Agena that had been launched 101 minutes earlier. The Agena successfully achieved orbit and waited for Gemini VIII in a 161-nm circular Earth orbit.

It took just under six (6) hours for Armstrong and Scott to catch-up and rendezvous with their Agena. The crew then kept station with the target vehicle for a period of about 36 minutes. Having assured themselves that all was well with the Agena, the world’s first successful docking was achieved at a Gemini mission elapsed time of 6 hours and 33 minutes.

Once the reality of the historic docking sank in, a delayed cheer erupted from the NASA and contractor team at Mission Control in Houston, Texas. Despite the complex orbital mechanics and delicate timing involved, Armstrong and Scott had actually made it look easy. Unfortunately, things were about to change with an alarming suddeness.

As the Gemini crew maneuvered the Gemini-Agena stack, their instruments indicated that they were in an uncommanded 30-degree roll. Using the Gemini’s Orbital Attiude and Maneuvering System (OAMS), Armstrong was able to arrest the rolling motion. However, once he let off the restoring thruster action, the combined vehicle began rolling again.

The crew’s next action was to turn off the Agena’s systems. The errant motion subsided. Several minutes elapsed with the control problem seemingly solved. Suddenly, the uncommanded motion of the still-docked pair started again. The crew noticed that the Gemini’s OAMS was down to 30% fuel. Could the problem be with the Gemini spacecraft and not the Agena?

The crew jettisoned the Agena. That didn’t help matters. The Gemini was now tumbling end over end at almost one revolution per second. The violent motion made it difficult for the astronauts to focus on the instrument panel. Worse yet, they were in danger of losing consciousness.

Left with no other alternative, Armstrong shut down his OAMS and activated the Reentry Control System reaction control system (RCS) in a desperate attempt to stop the dizzying tumble. The motion began to subside. Finally, Armstrong was able to bring the spacecraft under control.

That was the good news. The bad news for the crew of Gemini VIII was that the rest of the mission would now have to be aborted. Mission rules dictated that such would be the case if the RCS was activated on-orbit. There had to be enough fuel left for reentry and Gemini VIII had just enough to get back home safely.

Gemini VIII splashed-down in the Pacific Ocean 4,320 nm east of Okinawa. Mission elapsed time was 10 hours, 41 minutes and 26 seconds. Spacecraft and crew were safely recovered by the USS Leonard F. Mason.

In the aftermath of Gemini VIII, it was discovered that OAMS Thruster No. 8 had failed in the ON position. The probable cause was an electrical short. In addition, the design of the OAMS was such that even when a thruster was switched off, power could still flow to it. That design oversight was ultimately remediated so that subsequent Gemini missions would not be threatened by a re-occurence of the Gemini VIII anomaly.

Neil Armstrong and David Scott met their Goliath in orbit and defeated the beast. Armstrong received a quality increase for his exceptional efforts on Gemini VIII while Scott was promoted to Lieutenant Colonel. Both men were also awarded the NASA Exceptional Service Medal.

More significantly, their deft handling of the Gemini VIII emergency elevated both Armstrong and Scott within the ranks of the astronaut corps. Indeed, each man would ultimately land on the Moon and serve as mission commander in doing so; Neil Armstrong on Apollo 11 and David Scott on Apollo 15.

Posted in Aerospace, History

Piloting the Lunar Module

Fifty years ago this month, the Apollo Lunar Module (LM) was flown by an astronaut crew in space for the first time during the Apollo 9 earth-orbital mission. This technological achievement was critical to the success of the first lunar landing mission which occurred a little over 4 months later.

The Apollo Lunar Module (LM) was the world’s first true spacecraft in that it was designed to operate in vacuum conditions only. It was the third and final element of the Apollo spacecraft; the first two elements being the Command Module (CM) and the Service Module (LM).

The LM had its own propulsion, life-support and GNC systems. The vehicle weighed about 33,000 lbs on Earth and was used to transport a pair of astronauts from lunar orbit to the lunar surface and back into lunar orbit.

The spacecraft was really a two-stage vehicle; a descent stage and an ascent stage weighing 23,000 lbs and 10,000 lbs on Earth, respectively. The thrust of descent stage rocket motor could be throttled and produced a maximum thrust of 10,000 lbs while the ascent stage rocket motor was rated at 3,500 lbs of thrust.

On Monday, 03 March 1969, Apollo 9 was rocketed into earth-orbit by the mighty Saturn V launch vehicle. The primary purpose of this mission was to put the first LM through its paces by astronauts preparatory to the first lunar landing attempt.

During the 10-day mission, the crew of Commander James A. McDivitt, CM Pilot David R. Scott and LM Pilot Russell L. “Rusty” Schweickart fully verified all moon landing-specific operational aspects (short of an actual landing) of the LM. Key orbital activities included multiple-firings of both LM rocket motors and several rendezvous and docking exercises in which the LM flew as far away as 113 miles from the CM-SM pair.

By the time the crew splashed-down in the Atlantic Ocean on Thursday, 13 March 1969, America had a new operational spacecraft and a fighting chance to land men on the moon and safely return them to the Earth before the end of the decade.

Posted in Aerospace, History

Hands-Off Landing

Forty-nine years ago this month, a USAF F-106A Delta Dart (S/N 58-0787) out of Malmstrom AFB, Montana made a wheels-up landing in a farmer’s field despite the fact that there was no pilot onboard.  The pilot, Lieutenant Gary Foust, had ejected earlier when he was unable to recover the aircraft from a flat spin.  This incident became known in popular culture as “The Cornfield Bomber”.

On Monday, 02 February 1970, a trio of pilots from the 71st Fighter Interceptor Squadron (FIS) took-off from Malmstrom AFB, Montana for the purpose of practicing air combat maneuvers.  A fourth pilot had intended to be part of this group but was forced to abort the mission when his aircraft’s drag parachute strangely deployed on the ramp.

The pilots who took to the air that day were Major Thomas Curtis, Major James Lowe, and Faust.  Each man was at the controls of a Convair F-106A Delta Dart; aka “The Ultimate Interceptor”.   The three-ship formation departed Malmstrom for an area roughly 90 miles north of the base designated for the flying of air combat maneuvers and engagements.

The practice session began with a two-on-one head-on engagement.  Approaching the other two aircraft at Mach 1.90 in full afterburner, Captain Curtis pulled his aircraft into the vertical.  His intent was to induce the other pilots to follow him upstairs.  They did so.  In passing through 38,000 feet, he executed a vertical rolling scissors maneuver.  However, Curtis had superior energy at the pull-up point.   Thus, neither Lowe nor Foust could gain a tactical advantage in the fight.  When Curtis executed a high-g rudder reversal, Foust attempted to stay with him.  That’s when things deteriorated rapidly for Foust.

Foust flew his F-106A into an accelerated stall around 35,000 feet as he attempted to maintain position with Curtis.  That is, his aircraft exceeded the stall angle-of-attack while simultaneously losing speed due to the motion-retarding effects of gravity and drag due to lift.  The F-106A fell off into a series of post-stall gyrations followed by entry into a flat spin.  The flat spin is a high angle-of-attack, deep stall condition from whence recovery was typically not possible in a Delta Dart.

Notwithstanding the futility of the task, Foust diligently applied anti-spin procedures in textbook fashion.  However, the aircraft continued to fall in a flat spin.  In desperation, Foust deployed his drag chute hoping that it would act as an anti-spin device.  Unfortunately, the chute became totally useless for that purpose when it wrapped itself around the vertical tail of his falling steed.  Running out of altitude and time, Foust had no other recourse but to abandon his airplane.  He did so somewhere around 12,000 feet.

Foust was rocketed out of his Delta Dart and got a good chute.  He landed in the Bear Paw Mountains, and fortunately was brought to safety by local citizens on snowmobiles.  However, to the utter amazement of Foust, Curtis, and Lowe, the abandoned delta-winged aircraft snapped out of its flat spin and began to glide.  Apparently, the equal and opposite reaction of the aircraft to the force produced by the rocket-powered ejection seat forced the nose of the airplane below the stall angle-of-attack.  Thus, the wing began to produce lift again.  Further, as part of his anti-spin procedures, Foust had configured the controls of the Delta Dart in take-off trim and brought the throttle to idle.

The net state of affairs now was that the F-106A became a pretty good glider.  Gliding at about 175 knots, it ultimately made a wheels-up landing in a farmer’s snow-covered field near Big Sandy, Montana.  The landing was aided by ground effect which enhanced the lift on the airplane as the vehicle neared the ground.  Incredibly, the wings remained level throughout the landing slide-out.  Further, late in the landing, the F-106A magically turned 20 degrees from its touchdown azimuth and avoided running into a pile of rockets directly in its path.  In doing so, the airplane slipped through an opening in a fence around the farmer’s property and came to a stop.

When authorities approached the Delta Dart, they found that its canopy was gone, its ejection seat was gone, and so was its pilot.  A look into the cockpit revealed that the radar scope was still sweeping for targets.  And, although in idle, the still running turbojet produced a bit of thrust.  Thus, periodically, the vehicle would lurch forward when the restraining snow around the it melted.  Almost two hours later, the turbojet finally stopped running when the aircraft fuel supply ran out.

Remarkably, the pilotless Delta Dart sustained little damage despite the wheels-up landing.  The aircraft was later trucked out of the area and sent to McClellan AFB in California for repairs.  It ultimately was returned to service with the 71st FIS.  Later, it entered the inventory of the 49th Fighter Interceptor Squadron at Grifffiss AFB, New York.  Fittingly, a measure of closure was accorded (then) Major Gary Foust when he flew this same aircraft again in 1979.  Today, USAF F-106A Delta Dart, S/N 58-0787 sits on display for posterity at the USAF National Museum at Wright-Patterson AFB in Dayton, Ohio.

Posted in Aerospace, History

Mercury Into Orbit

Fifty-seven years ago today, Project Mercury Astronaut John Herschel Glenn, Jr. became the first American to orbit the Earth. Glenn’s spacecraft name and mission call sign was Friendship 7.

Mercury-Atlas 6 (MA-6) lifted-off from Cape Canaveral’s Launch Complex 14 at 14:47:39 UTC on Tuesday, 20 February 1962. It was the first time that the Atlas LV-3B booster was used for a manned spaceflight.

Three-hundred and twenty seconds after lift-off, Friendship 7 achieved an elliptical orbit measuring 143 nm (apogee) by 86 nm (perigee). Orbital inclination and period were 32.5 degrees and 88.5 minutes, respectively.

The most compelling moments in the United States’ first manned orbital mission centered around a sensor indication that Glenn’s heat shield and landing bag had become loose at the beginning of his second orbit. If true, Glenn would be incinerated during entry.

Concern for Glenn’s welfare persisted for the remainder of the flight and a decision was made to retain his retro package following completion of the retro-fire sequence. It was hoped that the 3 flimsy straps holding the retro package would also hold the heat shield in place.

During Glenn’s return to the atmosphere, both the spent retro package and its restraining straps melted in the searing heat of re-entry. Glenn saw chunks of flaming debris passing by his spacecraft window. At one point he radioed, “That’s a real fireball outside”.

Happily, the spacecraft’s heat shield held during entry and the landing bag deployed nominally. There had never really been a problem. The sensor indication was found to be false.

Friendship 7 splashed-down in the Atlantic Ocean at a point 432 nm east of Cape Canaveral at 19:43:02 UTC. John Glenn had orbited the Earth 3 times during a mission which lasted 4 hours, 55 minutes and 23 seconds. In short order, spacecraft and astronaut were successfully recovered aboard the USS Noa.

John Glenn became a national hero in the aftermath of his 3-orbit mission aboard Friendship 7. It seemed that just about every newspaper page in the days following his flight carried some sort of story about his historic feat. Indeed, it is difficult for those not around back in 1962 to fully comprehend the immensity of Glenn’s flight in terms of what it meant to the United States.

John Herschel Glenn, Jr. passed away on 08 December 2016 at the age of 95. His trusty Friendship 7 spacecraft is currently on display at the Smithsonian National Air and Space Museum in Washington, DC.

Posted in Aerospace, History

Supersonic Escape

Sixty-four years ago this month, North American test pilot George F. Smith became the first man to survive a low altitude, high dynamic pressure ejection from an aircraft in supersonic flight. Smith ejected from his F-100A Super Sabre at 777 MPH (Mach 1.05) as the crippled aircraft passed through 6,500 feet in a near-vertical dive.

On the morning of Saturday, 26 February 1955, North American Aviation (NAA) test pilot George F. Smith stopped by the company’s plant at Los Angeles International Airport to submit some test reports. Returning to his car, he was abruptly hailed by the company dispatcher. A brand-new F-100A Super Sabre needed to be test flown prior to its delivery to the Air Force. Would Mr. Smith mind doing the honors?

Replying in the affirmative, Smith quickly donned a company flight suit over his street clothes, got the rest of his flight gear and pre-flighted the F-100A Super Sabre (S/N 53-1659). After strapping into the big jet, Smith went through the normal sequence of aircraft pre-launch flight control and system checks. While the control column did seem a bit stiff in pitch, Smith nonetheless decided that his aerial steed was ready for flight.

Smith executed a full afterburner take-off to the west. The fleet Super Sabre eagerly took to the air. Accelerating and climbing, the aircraft was almost supersonic as it passed through 35,000 feet. Peaking out around 37,000 feet, Smith sensed a heaviness in the flight control column. Something wasn’t quite right. The jet was decidedly nose heavy. Smith countered by pulling aft stick.

The Super Sabre did not respond at all to Smith’s control inputs. Instead, it continued an un-commanded dive. Shallow at first, the dive steepened even as the 215-lb pilot pulled back on the stick with all of his might. But all to no avail. The jet’s hydraulic system had failed. As the stricken aircraft now accelerated toward the ground, Smith rightly concluded that this was going to be a short ride.

George Smith knew that he had only one alternative now; Eject. However, he also knew that the chances were quite small that he would survive what was quickly shaping-up to be a quasi-supersonic ejection. Suddenly, over the radio, Smith heard another Super Sabre pilot flying in his vicinity frantically yell: “Bail out, George!” So exhorted, the test pilot complied.

Smith jettisoned his canopy. The roar from the airstream around him was unlike anything he had ever heard. Almost paralyzed with fear, Smith reflexively hunkered-down in the cockpit. The exact wrong thing to do. His head needed to be positioned up against the seat’s headrest and his feet placed within retraining stirrups prior to ejection. But there was no time for any of that now. Smith pulled the ejection seat trigger.

George Smith’s last recollection of his nightmare ride was that the Mach Meter read 1.05; 777 mph at the ejection altitude of 6,500 feet above the Pacific Ocean. These flight conditions corresponded to a dynamic pressure of 1,240 pounds per square foot. As he was fired out of the cockpit and into the harsh air stream, Smith’s body was subjected to an astounding drag force of around 8,000 lbs producing on the order of 40-g’s of deceleration.

Mercifully, Smith did not recall what came next. The ferocious wind blast stripped him of his helmet, oxygen mask, footwear, flight gloves, wrist watch and even his ring. Blood was forced into his head which became grotesquely swollen and his facial features unrecognizable. His eyelids fluttered and his eyes were tortuously mauled by the aerodynamic and inertial load of his ejection. Smith’s internal organs, most especially his liver, were severely damaged. His body was horribly bruised and beaten as it flailed end-over-over end uncontrollably.

Smith and his seat parted company as programmed followed by automatic deployment of his parachute. The opening forces were so high that a third of the parachute material was ripped away. Thankfully, the remaining portion held together and the unconscious Smith landed about 75 yards away from a fishing vessel positioned about a half-mile form shore. Providentially, the boat’s skipper was a former Navy rescue expert. Within a minute of hitting the water, Smith was rescued and brought onboard.

George Smith was hovering near death when he arrived at the hospital. In severe shock and with only a faint pulse, doctors quickly went to work. Smith awoke on his sixth day of hospitalization. He could hear, but he couldn’t see. His eyes had sustained multiple subconjunctival hemorrhages and the prevailing thought at the time was that he would never see again.

Happily, George Smith did recover almost fully from his supersonic ejection experience. He spent seven (7) months in the hospital and endured several operations. During that time, Smith’s weight dropped to 150 lbs. He was left with a permanently damaged liver to the extent that he could no longer drink alcohol. As for Smith’s vision, it returned to normal. However, his eyes were ever after somewhat glare-sensitive and slow to adapt to darkness.

Not only did George Smith return to good health, he also got back in the cockpit. First, he was cleared to fly low and slow prop-driven aircraft. Ultimately, he got back into jets, including the F-100A Super Sabre. Much was learned about how to markedly improve high speed ejection survivability in the aftermath of Smith’s supersonic nightmare. He in essence paid the price so that others would fare better in such circumstances as he endured.

It is possible that George Smith was not the first pilot to eject supersonically. USN LCdr Authur Ray Hawkins survived ejection from his stricken Grumman F9F-6 Cougar in 1953. Aircraft speed at ejection was never definitively determined, but was estimated to be between 688 (Mach 0.99) and 782 mph (Mach 1.16). In any event, the dynamic pressure and therefore the airloads associated with Hawkins ejection were less than half that of Smith’s punch-out.

George Smith was thirty-one (31) at the time of his F-100A mishap. He lived a happy and productive thirty-nine (39) more years after its occurrence. Smith passed from this earthly scene in 1994.

Posted in Aerospace, History

USAF YF-16 First Flight

Forty-five years ago this month, the USAF/General Dynamics YF-16 Lightweight Fighter (LWF) took to the air on its official first flight with General Dynamics test pilot Phil Oestricher at the controls. The YF-16 would go on to win the high stakes Air Combat Fighter competition following a head-to-head fly-off against Northrop’s very capable YF-17 Cobra.

The YF-16 was General Dynamics entry into the USAF Lightweight Fighter Program of the 1970’s. Its basic design was based on USAF Colonel John Boyd’s Energy Maneuverability (EM) Theory which posited that an aircraft with superior energy capability would defeat an aircraft of lesser energy capability in air combat. To achieve such, EM Theory dictated a small, lightweight aircraft having a high thrust-to-weight ratio, which permitted maneuvering at minimum energy loss. The YF-16 was an embodiment of this requirement.

The official first flight of the YF-16 (S/N 72-1567) took place on Saturday, 02 February 1974 at Edwards Air Force Base, California. General Dynamics test pilot Phil Oestricher (pronounced Ol-Striker) did the piloting honors. The nimble aircraft performed very well and was a delight to fly. Oestricher landed uneventfully following a brief test hop that saw the YF-16 reach 400 mph and 30,000 feet.

Interestingly, the real first flight of the YF-16 inadvertently occurred on Sunday, 20 January 1974 during what was supposed to be a high-speed taxi test. As the aircraft accelerated rapidly down the runway, Oestricher raised the nose slightly and applied aileron control to check lateral response. To the pilot’s surprise, the aircraft entered a roll oscillation with amplitudes so high that the left wing and right stabilator alternately struck the surface of the runway.

As Oestricher desperately fought to maintain control of his wild steed, the situation became increasingly dire as the YF-16 began to veer to the left. Realizing that going into the weeds at high speed was a prescription for disaster, the test pilot quickly elected to jam the throttle forward and attempt to get the YF-16 into the air. The outcome of this decision was not immediately obvious as Oestricher continued to struggle for control while waiting for his airspeed to increase to the point that there was lift sufficient for flight.

When the YF-16 finally became airborne, it departed the runway on a heading roughly 45 degrees to the left of the centerline. Oestricher somehow maintained control of the aircraft during the rugged lift-off and early climbout phases of flight. The pilot then successfully executed a go-around, entry into final approach, and landing back on the departure runway. A tough way to earn a day’s pay by any standard!

History records that the YF-16 went on to win the Air Combat Fighter (ACF) competition with Northrop’s YF-17 Cobra. The production aircraft became known as the F-16 Fighting Falcon, of which more than 4,500 aircraft, in numerous variants, were built between 1976 and 2010. The now-famous aircraft has clearly fulfilled the measure of its creation as evidenced by its presence in the military inventory of more than 25 countries worldwide. Significantly, America’s Ambassadors in Blue, The United States Air Force Thunderbirds, have flown the F-16 in air demonstrations since 1983.

While its initial foray into the air did not necessarily lend confidence that such would be the case, the YF-16 did survive its flight test career. Aviation aficionados may view the actual aircraft at the Virginia Air and Space Center located in Hampton, Virginia.

Posted in Aerospace, History

America in Orbit

Sixty-one years ago today, the United States successfully orbited the country’s first space satellite. Known as Explorer I, the artificial moon went on to discover the Van Allen Radiation Belts, the extensive system of charged particles trapped in the magnetosphere that surrounds the Earth.

The Explorer I satellite was designed and fabricated by the Jet Propulsion Laboratory (JPL) under the direction of Dr. William J. Pickering. The satellite’s instrumentation unit measured 37.25 inches in length, 6.5 inches in diameter, and had a mass of only 18.3 lbs. With its burned-out fourth stage solid rocket motor attached, the total on-orbit mass of the pencil-like satellite was 30.8 lbs.

Explorer I was launched aboard a Jupiter-C (aka Juno I) launch vehicle from LC-26 at Cape Canaveral, Florida on Friday, 31 January 1958. Lift-off at occurred at 22:48 EST (0348 UTC). With all four stages performing as planned, Explorer I was inserted into a highly elliptical orbit having an apogee of 1,385 nm and a perigee of 196 nm.

Arguably the most historic achievement of the Explorer I mission was the discovery of a system of charged particles or plasma within the magnetosphere of the Earth. These belts extend from an altitude of roughly 540 to 32,400 nm above mean sea level. Most of the plasma that forms these belts originates from the solar wind and cosmic rays. The radiation levels within the Van Allen Radiation Belts (named in honor of the University of Iowa’s Dr. James A. Van Allen) are such that spacecraft electronics and astronaut crews must be shielded from the adverse effects thereof.

Explorer I operational life was limited by on-board battery life and lasted a mere 111 days. However, it soldiered-on in orbit until reentering the Earth’s atmosphere over the Pacific Ocean on Tuesday, 31 March 1970. During the 147 months it spent in space, Explorer I orbited the Earth more than 58,000 times. Data obtained and transmitted by the satellite contributed markedly to mankind’s understanding of the Earth’s space environment.

Perhaps the greatest legacy of Explorer I was that it was the first satellite orbited by the United States. Unknown to most today, this accomplishment was absolutely vital to America’s security, and indeed that of the free world, at the time. The Soviet Union had been first in space with the orbiting of the much larger Sputnik I and II satellites in late 1957. However, Explorer I showed that America also had the capability to orbit a satellite. History records that this capability would quickly grow and ultimately lead to the country’s preeminence in space.

Posted in Aerospace, History

HAM Into Space

Fifty-eight years ago this month, NASA successfully conducted a critical flight test of the space agency’s Mercury-Redstone launch vehicle which helped clear the way for the United States’ first manned suborbital spaceflight. Riding the Mercury spacecraft into space and back was a diminutive 44-month old male chimpanzee by the name of HAM.

Project Mercury was America’s first manned spaceflight program. Simply stated, Mercury helped us learn how to fly astronauts in space and return them safely to earth. A total of six (6) manned missions were flown between May of 1961 and May of 1963. The first two (2) flights were suborbital shots while the final four (4) flights were full orbital missions. All were successful.

The Mercury spacecraft weighed about 3,000 lbs, measured 9.5-ft in length and had a base diameter of 6.5-ft. Though diminutive, the vehicle contained all the systems required for manned spaceflight. Primary systems included guidance, navigation and control, environmental control, communications, launch abort, retro package, heatshield, and recovery.

Mercury spacecraft launch vehicles included the Redstone and Atlas missiles. Both were originally developed as weapon systems and therefore had to be man-rated for the Mercury application. Redstone, an Intermediate Range Ballistic Missile (IRBM), was the booster for Mercury suborbital flights. Atlas, an Intercontinental Ballistic Missile (ICBM), was used for orbital missions.

Early Mercury-Redstone (MR) flight tests did not go particularly well. The subject missions, MR-1 and MR-1A, were engineering test and development flight tests flown with the intent of man-rating both the converted launch vehicle and new manned spacecraft.

MR-1 hardly flew at all in that its rocket motor shut down just after lift-off. After soaring to the lofty altitude of 4-inches, the vehicle miraculously settled back on the launch pad without toppling over and detonating its full load of propellants. MR-1A flew, but owing to higher-than-predicted acceleration, went much higher and farther than planned. Nonetheless, MR flight testing continued in earnest.

The objectives of MR-2 were to verify (1) that the fixes made to correct MR-1 and MR-1A deficiencies indeed worked and (2) proper operation of a bevy of untested systems as well. These systems included environmental control, attitude stabilization, retro-propulsion, voice communications, closed-loop abort sensing and landing shock attenuation. Moreover, MR-2 would carry a live biological payload (LBP).

A 44-month old male chimpanzee was selected as the LBP. He was named HAM in honor of the Holloman Aerospace Medical Center where the primate trained. HAM was taught to pull several levers in response to external stimuli. He received a banana pellet as a reward for responding properly and a mild electric shock as punishment for incorrect responses. HAM wore a light-weight flight suit and was enclosed within a special biopack during spaceflight.

On Tuesday, 31 January 1961, MR-2 lifted-off from Cape Canaveral’s LC-5 at 16:55 UTC. Within one minute of flight, it became obvious to Mission Control that the Redstone was again over-accelerating. Thus, HAM was going to see higher-than-planned loads at burnout and during reentry. Additionally, his trajectory would take him higher and farther downrange than planned. Nevertheless, HAM kept working at his lever-pulling tasks.

The Redstone burnout velocity was 5,867 mph rather than the expected 4,400 mph. This resulted in an apogee of 137 nm (100 nm planned) and a range of 367 nm (252 nm predicted). HAM endured 14.7 g’s during entry; well above the 12 g’s planned. Total flight duration was 16.5 minutes; several minutes longer than planned.

Chillingly, HAM’s Mercury spacecraft experienced a precipitous drop in cabin pressure from 5.5 psig to 1 psig just after burnout. High flight vibrations had caused the air inlet snorkel valve to open and dump cabin pressure. HAM was both unaware of and unaffected by this anomaly since he was busy pulling levers within the safety of his biopack.

HAM’s Mercury spacecraft splashed-down at 17:12 UTC about 52 nm from the nearest recovery ship. Within 30 minutes, a P2V search aircraft had spotted HAM’s spacecraft (now spaceboat) floating in an upright position. However, by the time rescue helicopters arrived, the Mercury spacecraft was found floating on its side and taking on sea water.

Apparently, a combination of impact damage to the spacecraft’s pressure bulkhead and the open air inlet snorkel valve resulted in HAM’s spacecraft taking on roughly 800 lbs of sea water. Further, heavy ocean wave action had really hammered HAM and the Mercury spacecraft. The latter having had its beryllium heatshield torn away and lost in the process.

Fortunately, one of the Navy rescue helicopters was able to retrieve the waterlogged spacecraft and deposit it safely on the deck of the USS Donner. In short order, HAM was extracted from the Mercury spacecraft. Despite the high stress of the day’s spaceflight and recovery, HAM looked pretty good. For his efforts, HAM received an apple and an orange-half.

While the MR-2 was judged to be a success, one more flight would eventually be flown to verify that the Redstone’s over-acceleration problem was fixed. That flight, MR-BD (Mercury-Redstone Booster Development) took place on Friday, 24 March 1961. Forty-two (42) days later USN Commander Alan Bartlett Shepard, Jr. became America’s first astronaut.

MR-2 was HAM’s first and only spaceflight experience. He quietly lived the next 17 years as a resident of the National Zoo in Washington, DC. His last 2 years were spent living at a North Carolina zoo. On Monday, 19 January 1983, HAM passed away at the age of 26. HAM is interred at the New Mexico Museum of Space History in Alamogordo, NM.

Posted in Aerospace, History

Skyray Debut

Sixty-six years ago this month, the USN/Douglas XF4D-1 Skyray fighter flew for the first time at Edwards Air Force Base in California. Douglas test pilot Robert O. Rahn was at the controls of the single-engine, carrier-based, supersonic-capable aircraft.

The Douglas XF4D-1 was the prototype version of the United States Navy’s F4D-1 Skyray. Designed to intercept adversary aircraft at 50,000 feet within 300 seconds of take-off, development of the Skyray began in the late 1940’s. As an aside, the Skyray nickname derived from the type’s large delta wing which gave it the appearance of a Manta ray.

The Skyray was originally designed to be powered by a Westinghouse XJ40-WE-6 turbojet capable of 7,000 lbs of sea level thrust. However, when significant developmental problems were encountered with that power plant, Douglas substituted an Allison J35-A-17 turbojet to support early flight testing of the XF4D-1. With a maximum sea level thrust of 5,000 lbs, the J35 rendered these early airframes significantly under-powered.

A pair of XF4D-1 Skyray airframes were built by Douglas. Ship No. 1 was assigned tail number BuAer 124586 while Ship No. 2 received the designation BuAer 124587.

On Tuesday, 23 January 1953, XF4D-1 Ship No. 1 (BuAer No 124586) departed Edwards Air Force Base on its first ride into the wild blue. Doing the piloting honors on this occasion was highly regarded Douglas test pilot Bob Rahn. The delta-winged beauty performed well on this maiden flight which concluded with Rahn making an uneventful landing back at Edwards.

Extensive flight testing of the Skyray, including carrier trials, continued through 1955. The Westinghouse XJ40-WE-8 appeared on the scene during this time. Rated at 11,600 lbs of sea level thrust in afterburner, this power plant allowed the Skyray to establish several speed records in California during October of 1953. Specifically, a speed of 752.944 mph was registered within a 3-kilometer course over the Salton Sea followed by 100-kilometer closed course mark of 728.11 mph at Edwards AFB.

Unfortunately, the XJ40 would prove to be very temperamental and unreliable. Inflight engine fires, explosions, and component failures constantly plagued the Skyray program. Westinghouse never did solve these problems to the satisfaction of the Navy. As a result, the service eventually opted to power production aircraft with the Pratt and Whitney J57-P-8 turbojet (10,200 lbs of sea level thrust).

The Douglas F4D-1 Skyray went on to serve with the United States Navy and Marines from 1956 through 1964. A total of 420 aircraft were produced. While never used in anger, the Skyray was a solid performer and served well in its intended role as a point design interceptor.

The Skyray holds the distinction of being the last fighter produced by the Douglas Aircraft Company before this legendary aerospace giant merged with McDonnell Aircraft to form McDonnell Douglas.

Posted in Aerospace, History