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An Improbable Landing

Fifty 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

EXPLORER I: America’s First Satellite

Sixty-two years ago to the day, 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, Uncategorized

Final Flight: Apollo AS-204

Fifty-three years ago this month the Apollo 204 prime crew perished as fire swept through their Apollo Block I Command Module (CM). The Apollo 204 crew of Command Pilot Vigil I. “Gus” Grissom, Senior Pilot Edward H. White II and Pilot Roger B. Chaffee had been scheduled to make the first manned flight of the Apollo Program some three weeks hence.

On Friday, 27 January 1967, during a plugs-out ground test on LC-34 at Cape Canaveral, Florida, a fire broke out in the Apollo 204 spacecraft at 23:31:04 UTC (6:31:04 pm EST). Shortly after, a chilling cry was heard across the communications network from Astronaut Chaffee: “We’ve got a fire in the cockpit”.

Believed to have started just below Grissom’s seat, the fire quickly erupted into an inferno that claimed the men’s lives in less than 30 seconds. While each received extensive 3rd degree burns, death was attributed to toxic smoke inhalation.

The Apollo 204 fire was most likely brought about by some minor malfunction or failure in equipment or wire insulation. This failure, which was never positively identified, initiated a sequence of events that culminated in the conflagration.

The post-mishap investigation uncovered numerous defects in CM Block I design, manufacturing, and workmanship. The use of a (1) pure oxygen atmosphere pressurized to 16.7 psia and (2) complex 3-component hatch design (that took a minimum of 90 seconds to open) sealed the astronauts’ fate.

A haunting irony of the tragedy is that America lost her first astronaut crew, not in the sideral heavens, but in a spacecraft that was firmly rooted to the ground.

Posted in Aerospace, Final Flight, History

Final Flight: STS-51L Challenger

Thirty-four years ago this month, the seven member crew of STS-51L perished when the Space Shuttle Challenger disintegrated 73 seconds after launch from LC-39B at Cape Canaveral, Florida. The tragedy was the first fatal in-flight mishap in the history of American manned spaceflight.

In remarks made at a memorial service held for the Challenger Seven in Houston, Texas on Friday, 31 January 1986, President Ronald Wilson Reagan expressed the following sentiments:

“The future is not free: the story of all human progress is one of a struggle against all odds. We learned again that this America, which Abraham Lincoln called the last, best hope of man on Earth, was built on heroism and noble sacrifice. It was built by men and women like our seven star voyagers, who answered a call beyond duty, who gave more than was expected or required and who gave it little thought of worldly reward.”

We take this opportunity to remember the noble fallen:

Francis R. (Dick) Scobee, Commander

Michael John Smith, Pilot

Ellison S. Onizuka, Mission Specialist One

Judith Arlene Resnik, Mission Specialist Two

Ronald Erwin McNair, Mission Specialist Three

S.Christa McAuliffe, Payload Specialist One

Gregory Bruce Jarvis, Payload Specialist Two

Speaking for grieving families and countrymen, President Reagan closed his eulogy with these words:

“Dick, Mike, Judy, El, Ron, Greg and Christa – your families and your country mourn your passing. We bid you goodbye. We will never forget you. For those who knew you well and loved you, the pain will be deep and enduring. A nation, too, will long feel the loss of her seven sons and daughters, her seven good friends. We can find consolation only in faith, for we know in our hearts that you who flew so high and so proud now make your home beyond the stars, safe in God’s promise of eternal life.”

Posted in Aerospace, Final Flight, History

Tall Tail Tale

Fifty-six years ago this week, a USAF/Boeing B-52H Stratofortress landed safely following structural failure of its vertical tail during an encounter with unusually severe clear air turbulence. The harrowing incident occurred as the aircraft was undergoing structural flight testing in the skies over East Spanish Peak, Colorado.

Turbulence is the unsteady, erratic motion of an atmospheric air mass. It is attributable to factors such as weather fronts, jet streams, thunder storms and mountain waves. Turbulence influences the motion of aircraft that are subjected to it. These effects range from slight, annoying disturbances to violent, uncontrollable motions which can structurally damage an aircraft.

Clear Air Turbulence (CAT) occurs in the absence of clouds. Its presence cannot be visually observed and is detectable only through the use of special sensing equipment. Hence, an aircraft can encounter CAT without warning. Interestingly, the majority of in-flight injuries to aircraft crew and passengers are due to CAT.

On Friday, 10 January 1964, USAF B-52H (S/N 61-023) took-off from Wichita, Kansas on a structural flight test mission. The all-Boeing air crew consisted of instructor pilot Charles Fisher, pilot Richard Curry, co-pilot Leo Coors, and navigator James Pittman. The aircraft was equipped with 3-axis accelerometers and other sensors to record in-flight loads and stresses.

An 8-hour flight was scheduled on a route that from Wichita southwest to the Rocky Mountains and back. The mission called for 10-minutes runs of 280, 350 and 400 KCAS at 500-feet AGL using the low-level mode of the autopilot. The initial portion of the mission was nominal with only light turbulence encountered.

However, as the aircraft turned north near Wagon Mound, New Mexico and headed along a course parallel to the mountains, increasing turbulence and tail loads were encountered. The B-52H crew then elected to discontinue the low level portion of the flight. The aircraft was subsequently climbed to 14,300 feet AMSL preparatory to a run at 350 KCAS.

At approximately 345 KCAS, the Stratofortress and its crew experienced an extreme turbulence event that lasted roughly 9 seconds. In rapid sequence the aircraft pitched-up, yawed to the left, yawed back to the right and then rolled right. The flight crew desperately fought for control of their mighty behemoth. But the situation looked grim. The order was given to prepare to bailout.

Finally, the big bomber’s motion was arrested using 80% left wheel authority. However, rudder pedal displacement gave no response. Control inputs to the elevator produced very poor response as well. Directional stability was also greatly reduced. Nevertheless, the crew somehow kept the Stratofortress flying nose-first.

The B-52H crew informed Boeing Wichita of their plight. A team of Boeing engineering experts was quickly assembled to deal with the emergency. Meanwhile, a Boeing-bailed F-100C formed-up with the Stratofortress and announced to the crew that most of the aircraft’s vertical tail was missing! The stricken aircraft’s rear landing was then deployed to add back some directional stability.

With Boeing engineers on the ground working with the B-52H flight crew, additional measures were taken in an effort to get the Stratofortress safely back on the ground. These measures included a reduction in airspeed, controlling aircraft center-of-gravity via fuel transfer, judicious use of differential thrust, and selected application of speed brakes.

Due to high surface winds at Wichita, the B-52H was vectored to Eaker AFB in Blytheville, Arkansas. A USAF/Boeing KC-135 was dispatched to escort the still-flying B-52H to Eaker and to serve as an airborne control center as both aircraft proceeded to the base. Amazingly, after flying 6 hours sans a vertical tail, the Stratofortress and her crew landed safely.

Safe recovery of crew and aircraft brought additional benefits. There were lots of structural flight test data! It was found that at least one gust in the severe CAT encounter registered at nearly 100 mph. Not only were B-52 structural requirements revised as a result of this incident, but those of other existing and succeeding aircraft as well.

B-52H (61-023) was repaired and returned to the USAF inventory. It served long and well after its close brush with catastrophe in January 1964. The aircraft spent the latter part of its flying career as a member of the 2nd Bomb Wing at Barksdale AFB, Louisiana. The venerable bird was retired from active service in July of 2008.

Posted in Aerospace, History

Upholding Honor

Seventy-one years ago this month, the USAF/Bell XS-1 became the first aircraft of any type to achieve supersonic flight during a climb from a ground take-off. The daring feat took place at Muroc Air Force Base with famed USAF Captain Charles E. “Chuck” Yeager at the controls of the rocket-powered XS-1.

Rocket-powered X-aircraft such as the XS-1, X-1A, X-2 and X-15 were air-launched from a larger carrier aircraft. With the test aircraft as its payload, this “mother ship” would take-off and climb to drop altitude using its own fuel load. This capability permitted the experimental aircraft to dedicate its entire propellant load to the flight research mission proper.

The USAF/Bell XS-1 was the first X-aircraft. It was carried to altitude by a USAF/Boeing B-29 mother ship. XS-1 air-launch typically occurred at 220 mph and 22,000 feet. On Tuesday, 14 October 1947, the XS-1 first achieved supersonic flight. The XS-1 would ultimately fly as fast as Mach 1.45 and as high as 71,902 feet.

All but two (2) of the early X-aircraft were Air Force developments. The exceptions were products of the United States Navy flight research effort; the USN/Douglas D-558-I Sky Streak and USN/Douglas D-558-II Sky Rocket. The Sky Streak was a turbojet-powered, straight-winged, transonic aircraft. The Sky Rocket was supersonic-capable, swept-winged, and rocket-powered. Each aircraft was originally designed to be ground-launched.

In the best tradition of inter-service rivalry, the Navy claimed that the D-558-I at the time was the only true supersonic airplane since it took to the air under its own power. Interestingly, the Sky Streak was able fly beyond Mach 1 only in a steep dive. Nonetheless, the Air Force was indignant at the Navy’s thinly-disguised insinuation that the XS-1 was somehow less of an X-aircraft because it was air-launched.

Motivated by the Navy’s affront to Air Force honor, the junior military service devised a scheme to ground-launch the XS-1 from Rogers Dry Lake at Muroc (now Edwards) Air Force Base. The aircraft would go supersonic in what was essentially a high performance take-off and climb. To boot, the feat was timed to occur just before the Navy was to fly its rocket-powered D-558-II Sky Rocket. Justice would indeed be righteously served!

XS-1 Ship No. 1 (S/N 46-062) was selected for the ground take-off mission. Captain Charles E. Yeager would pilot the sleek craft with Captain Jackie L. Ridley providing vital engineering support. Due to its somewhat fragile landing gear, the XS-1 propellant load was restricted to 50% of capacity. This provided approximately 100 seconds of rocket-powered flight.

On Wednesday, 05 January 1949, Yeager fired all four (4) barrels of his XLR-11 rocket motor. Behind 6,000 pounds of thrust, the XS-1 rapidly accelerated along the smooth surface of the dry lake. After a take-off roll of only 1,500 feet and with the XS-1 at 200 mph, Yeager pulled back on the control yoke. The XS-1 virtually leapt into the desert air.

The aerodynamic loads were so high during gear retraction that the actuator rod broke and the wing flaps tore away. Unfazed, Yeager’s eager steed continued to climb rapidly. Eighty seconds after brake release, the XS-1 hit Mach 1.03 passing through 23,000 feet. Yeager then brought the XS-1 to a wings level flight attitude and shutdown his XLR-11 power plant.

Following a brief glide back to the dry lake, Yeager executed a smooth dead-stick landing. Total flight time from lift-off to touchdown was on the order of 150 seconds. While a little worst for wear, the plucky XS-1 had performed like a champ and successfully accomplished something that it was really not designed to do.

Yeager was so excited during the take-off roll and high performance climb that he forgot to put his oxygen mask on! Potentially, that was a problem since the XS-1 cockpit was inerted with nitrogen. Fortunately, late in the climb, Yeager got his mask in place just before he went night-night for good.

Suffice it to say that the United States Navy was not particularly fond of the display of bravado and airmanship exhibited on that long-ago January day. The Air Force had emerged victorious in a classic contest of one-upmanship.  At a deeper level, Air Force honor had been upheld.  And, as was often the case in the formative years of the United States Air Force, it was a test pilot named Chuck Yeager who brought victory home to the blue suiters.

Posted in Aerospace, History

Last Man

Forty-seven years ago this month, NASA successfully conducted the sixth lunar landing mission of the Apollo Program. Known as Apollo 17, the flight marked the last time that men from the planet Earth explored the surface of the Moon.

Apollo 17 was launched from LC-39A at Cape Canaveral, Florida on Thursday, 07 December 1972. With a lift-off time of 05:33:00 UTC, Apollo 17 was the only night launch of the Apollo Program. Those who witnessed the event say that night turned into day as the incandescent exhaust plumes of the Saturn V’s quintet of F-1 engines lit up the sky around the Cape.

The target for Apollo 17 was the Taurus-Littrow valley in the lunar highlands. Located on the southeastern edge of Mare Serenitatis, the landing site was of particular interest to lunar scientists because of the unique geologic features and volcanic materials resident within the valley. Planned stay time on the lunar surface was three days.

The Apollo 17 crew consisted of Commander Eugene A. Cernan, Command Module Pilot (CMP) Ronald E. Evans and Lunar Module Pilot (LMP) Harrison H. Schmitt. While this was Cernan’s third space mission, both Evans and Schmitt were space rookies. Astronaut Schmitt was a professional geologist and the only true scientist to explore the surface of the Moon.

With Evans circling the Moon solo in the Command Module America, Cernan and Schmitt successfully landed their Lunar Module Challenger at 19:54:57 UTC on Monday, 11 December 1972. Their lunar stay lasted more than three days. The astronauts used the Lunar Rover for transport over the lunar surface as they conducted a trio of exploratory excursions that totaled more than 22 hours.

Cernan and Schmitt collected nearly 244 pounds of lunar geologic materials while exploring Taurus-Littrow. As on previous missions, the Apollo 17 crew deployed a sophisticated set of scientific instruments used to investigate the lunar surface environment. Indeed, the Apollo Lunar Surface Experiments Package (ALSEP) deployed during during lunar landing missions measured and transmitted vital lunar environmental data back to Earth through September 1977 when the data acquisition effort was officially terminated.

The Apollo 17 landing party departed the Moon at 22:54:37 UTC on Thursday, 14 December 1972. In a little over two hours, Challenger and America were docked. Following crew and cargo transfer to America, Challenger was later intentionally deorbited and impacted the lunar surface. The Apollo 17 crew then remained in lunar orbit for almost two more days to make additional measurements of the lunar environment.

At 23:35:09 UTC on Saturday, 16 December 1972, Apollo 17 blasted out of lunar orbit and headed home. Later, CMP Ron Evans performed a trans-Earth spacewalk to retrieve film from Apollo 17 ’s SIM Bay camera. Evans’ brave spacewalk occurred on Sunday, 17 December 1972 (69th anniversary of the Wright Brothers first powered flight) and lasted 65 minutes and 44 seconds.

Apollo 17 splashdown occurred near America Samoa in the Pacific Ocean at 19:24:59 UTC on Tuesday, 19 December 1972. America and her crew were subsequently recovered by the USS Ticonderoga.

Apollo 17 set a number of spaceflight records including: longest manned lunar landing flight (301 hours, 51 minutes, 59 seconds); longest lunar stay time (74 hours, 59 minutes, 40 seconds); total lunar surface extravehicular activity time (22 hours, 3 minutes, 57 seconds); largest lunar sample return (243.7 pounds), and longest time in lunar orbit (147 hours, 43 minutes, 37 seconds).

Apollo 17 successfully concluded America’s Apollo Lunar Landing Program. Of a sudden it seemed, America’s — and the world’s — greatest adventure was over. However, the anticipation was that the United States would return in the not-too-distant future. Indeed, Gene Cernan, the last man to walk on the Moon, spoke the following words from the surface:

“As I take man’s last step from the surface, back home for some time to come — but we believe not too long into the future — I’d like to just [say] what I believe history will record — that America’s challenge of today has forged man’s destiny of tomorrow. And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return, with peace and hope for all mankind. Godspeed the crew of Apollo 17.”

It has now been 47 years since the Commander of Apollo 17 spoke those stirring words from the valley of Taurus-Littrow.  Gene Cernan passed away  in January of 2017.  He and most space experts of his day figured we would surely have returned to the Moon by now.  Certainly in the 20th century.  Yet, there has been no return.  Thus, the historical record continues to list the name of Eugene A. Cernan as the last man to walk on the surface of the Moon.

Posted in Aerospace, History

The Wright Stuff

One-hundred and sixteen years ago today, the Wright Flyer became the first aircraft in history to achieve powered flight. The site of this historic event was Kill Devil Hills located near Kitty Hawk, North Carolina.

Americans Wilbur and Orville Wright began their legendary aeronautical careers in 1899. In a matter of just four short years, the brothers would go from complete aeronautical novices to inventors and pilots of the world’s first successful powered aircraft. Neither man attended college nor received even a high school diploma.

The Wright Flyer measured roughly 21 feet in length and had a wing span of approximately 40 feet. The biplane aircraft had an empty weight of 605 lbs. Power was provided by a single 12 horsepower, 4-cylinder engine that drove twin 8.5 foot, two-blade propellers.

The Flyer made a powered take-off run along a 60-foot wooden guide rail. The aircraft was mounted on a two-wheel dolly that rode along the track and was jettisoned at lift-off. The Flyer pilot lay prone in the middle of the lower wing. Twin elevator and rudder surfaces provided pitch and yaw control, respectively. Roll control was via differential wing warping.

The Wright Brothers had come close to achieving a successful powered flight with the Wright Flyer on Monday, 14 December 1903. Wilbur, who had won the coin toss, was the pilot for the initial attempt. However, the Flyer stalled and hit the ground sharply just after take-off. Wilbur was unhurt, but repair of the damaged aircraft would take two days.

The next attempt flight took place on Thursday, 17 December 1903. The weather was terrible. Windy and rainy. Even after the rain abated, the wind continued to blow in excess of 20 mph. The Wrights decided to fly anyway. It was now Orville’s turn as command pilot.

Orville took his position on the Flyer and was quickly launched into the wind. Once airborne, the aircraft proved difficult to control as it porpoised up and down along the flight path. Nonetheless, Orville kept the Flyer in the air for 12 seconds before landing 120 feet from the take-off point. Other than a damaged skid, the aircraft was intact and the pilot unhurt. Powered flight was a reality!

Three more flights followed on that momentous occasion as the two brothers alternated piloting assignments. The fourth flight was the longest in both time aloft and distance flown. With Wilbur at the controls, the Wright Flyer flew for 59 seconds and landed 852 feet from the take-off point.

The Wright Brothers father, Milton, would soon learn of the epic events that December day in North Carolina. Orville’s verbatim Western Union telegram message sent to Dayton, Ohio read:

Success four flights thursday morning all against twenty one mile wind started from level with engine power alone average speed through air thirty one miles longest 57 [sic] seconds inform press home Christmas.

Posted in Aerospace, History

Final Flight: NF-104A, Ship 3

Fifty-six years ago to the day, USAF NF-104A (S/N 56-762; Ship 3) crashed to destruction following a rocket-powered zoom to 101,600 feet above mean sea level (AMSL). The pilot, USAF Colonel Charles E. “Chuck” Yeager, was seriously injured, but survived when he successfully ejected from the stricken aircraft approximately 5,000 feet above ground level (AGL).

The USAF/Lockheed NF-104A was designed to provide spaceflight-like training experience for test pilots attending the Aerospace Research Pilot School (ARPS) at Edwards Air Force Base, California. The type was a modification of the basic F-104A Starfighter aircraft. Three copies of the NF-104A were produced (S/N’s 56-0756, 56-0760 and 56-0762). It was the ultimate zoom flight platform.

In addition to a stock General Electric J79-GE-3 turbojet, the NF-104A was powered by a Rocketdyne LR121-NA-1 rocket motor. The J79 generated 15,000 pounds of thrust in afterburner and burned JP-4. The LR-121 produced 6,000 pounds of thrust and burned a combination of JP-4 and 90% hydrogen peroxide. Rocket motor burn time was on the order of 90 seconds.

Around 1400 hours PST on Tuesday, 10 December 1963, Colonel Yeager took-off from Edwards Air Force Base to attempt his second zoom flight of the day. That morning, he had zoomed NF-104A, S/N 56-760 to an altitude of 108,700 feet. Four days earlier, Yeager had zoomed the same airplane to the highest altitude he would ever achieve in the type; 110,500 feet AMSL.

The zoom apex altitude for the ill-fated afternoon flight was only 101,600 feet AMSL with rocket motor burnout taking place 5 seconds post-apogee. That is, the aircraft was already on the descending leg of the zoom trajectory and in the early stages of reentry. Yeager later reported that the aircraft angle-of-attack at that point was on the order of 50 deg; a figure that is well past the NF-104A pitch-up angle-of-attack (i.e., 14-17 deg). Yeager had flown the aircraft this way on previous zoom flights and had always been able to lower the nose via reaction control system (RCS) inputs.

Unfortunately, the RCS did not not have sufficient pitch control authority to bring the nose down on the mishap flight. As a result, the aircraft began the reentry in an extremely nose-high attitude.  As the dynamic pressure rapidly built-up, the NF-104A departed controlled flight and went through a series of post-stall gyrations between 90,000 and 65,000 feet. These gyrations ultimately led to a series of flat spins occurring between 65,000 and 20,000 feet.

Running out of altitude, Yeager desperately deployed his drag parachute as an anti-spin device. This action indeed stopped the flat spin. Airspeed picked-up to 180 KIAS with the aircraft hanging in the chute, but the pilot was unable to get an air-start on his J79 turbojet which had spooled down to 6% of maximum RPM. At 12,000 feet, Yeager jettisoned his drag chute and the NF-104A immediately pitched-up again into a flat spin. After three-quarters of a turn, Yeager ejected about 5,000 feet AGL. Yeager landed close to where the mishap aircraft had impacted and was in a great deal of pain due to burns he received during the ejection process. Happily, he survived this traumatic event and recovered completely from his injuries.

Objective analysis of the loss of NF-104A, S/N 56-762 reveals that the aircraft simply was not flown in a manner commensurate with the intricacies of the zoom environment. The critical importance of quickly intercepting and maintaining the target inertial pitch angle during pull-up had been repeatedly demonstrated by other test pilots as had proper control of aircraft angle-of-attack during reentry. Colonel Yeager elected not to fly the aircraft in accordance with these dictates.

In all of his NF-104A zoom attempts, Colonel Yeager consistently flew the airplane over the top at angles-of-attack well beyond the pitch-up value. RCS control authority was sufficient to lower the nose to sub-pitch-up angles-of-attack just prior to reentry on all but the mishap flight. Unfortunately, the low apex altitude (101,600 feet AMSL) of that zoom resulted in a higher dynamic pressure that, in conjunction with very high angles-of-attack, produced a nose-up aerodynamic pitching moment that the RCS could not overcome.

The aircraft mishap of 10 December 1963 forever changed the way in which NF-104A pilots would be allowed to fly the rocket-powered zoom mission. Prior to the mishap, the NF-104A had been zoomed to an altitude of 120,800 feet AMSL by USAF Major Robert W. Smith on 06 December 1963. This unofficial United States record still stands today. After a mishap investigation, NF-104A maximum altitude was limited to 108,000 feet AMSL. This restricted performance was mandated ostensibly out of concern for the safety of ARPS student test pilots.

The ultimate and lasting result of the post-mishap restriction on NF-104A flight performance was that it did a great disservice to ARPS student test pilots in that it made their spaceflight training experience something less than what it could and should have been. It is ironic that, although the correct manner in which to zoom the airplane had been repeatedly validated by USAF and Lockheed test pilots prior to the 56-0762 mishap, the decision to restrict NF-104A performance was based on a single flight which clearly demonstrated how not to fly the airplane.

Posted in Aerospace, Final Flight, History

Zoom Flight Record

Fifty-six years ago to the day, USAF Major Robert W. Smith zoomed the rocket-powered USAF/Lockheed NF-104A to an unofficial world record altitude of 120,800 feet. This mark still stands as the highest altitude ever achieved by a United States aircraft from a runway take-off.

A zoom maneuver is one in which aircraft kinetic energy (speed) is traded for potential energy (altitude). In doing so, an aircraft can soar well beyond its maximum steady, level altitude (service ceiling). The zoom maneuver has both military and civilian flight operations value.

The USAF/Lockheed NF-104A was designed to provide spaceflight-like training experience for test pilots attending the Aerospace Research Pilot School (ARPS) at Edwards Air Force Base, California. The type was a modification of the basic F-104A Starfighter aircraft. Three copies of the NF-104A were produced (S/N’s 56-0756, 56-0760 and 56-0762). It was the ultimate zoom flight platform.

In addition to a stock General Electric J79-GE-3 turbojet, the NF-104A was powered by a Rocketdyne LR121-NA-1 rocket motor. The J79 generated 15,000 pounds of thrust in afterburner and burned JP-4. The LR-121 produced 6,000 pounds of thrust and burned a combination of JP-4 and 90% hydrogen peroxide. Rocket motor burn time was on the order of 90 seconds.

The NF-104A was kinematically capable of zooming to altitudes approaching 125,000 feet. As such, it was a combined aircraft, rocket, and spacecraft. The pilot had to blend aerodynamic and reaction controls in the low dynamic pressure environment near the zoom apex. He was also required to fly in a full pressure suit for survival at altitudes beyond the Armstrong Line.

On Friday, 06 December 1963, Bob Smith took-off from Edwards and headed west for the Pacific Ocean. Out over the sea, he changed heading by 180 degrees in preparation for the zoom run-in. At a point roughly 100 miles out, Smith then accelerated the NF-104A (S/N 56-0760) along a line that would take him just north of the base. Arriving at Mach 2.4 and 37,000 feet, Smith then initiated a 3.75-g pull to a 70-degree aircraft pitch angle. Turbojet and rocket were at full throttle.

Things happened very quickly at this point. Smith brought the J79 turbojet out of afterburner at 65,000 feet and then moved the throttle to the idle detent at 80,000 feet. The rocket motor burned-out around 90,000 feet. Smith controlled the aircraft (now spacecraft) over the top of the zoom using 3-axis reaction controls. The NF-104A’s arcing parabolic trajectory subjected him to 73 seconds of weightlessness. Peak altitude achieved was 120,800 feet above mean sea level.

On the back side of the zoom profile, Bob Smith restarted the windmilling J79 turbojet and set-up for landing at Edwards. He touched down on the main runway and rolled out uneventfully. Total mission time from brake-release to wheels-stop was approximately 25 minutes.

Much more could be said about the NF-104A and its unique mission. Suffice it to say here that two of the aircraft ultimately went on to serve in the ARPS from 1968 to 1971. The only remaining aircraft today is 56-0760 which sits on a pole in front of the USAF Test Pilot School (TPS) at Edwards.

Bob Smith went on to make many other noteworthy contributions to aviation and his nation. Having flown the F-86 Sabre in Korea, he volunteered to fly combat in Viet Nam in his 40th year. Stationed at Korat AFB in Thailand, he commanded the 34th Fighter Squadron of the 388th Tactical Fighter Wing. Smith flew 100 combat missions in the fabled F-105D Thunderchief; many of which involved the infamous Pack VI route in North Viet Nam.

Bob Smith was a true American hero. Like so many of the airmen of his day, Smith was a man whose dedication, service, and courage went largely unnoticed and underappreciated by his fellow countrymen. Bob Smith’s final flight came just 3 months shy of his 82nd birthday on Thursday, 19 August 2010.

Posted in Aerospace, History
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