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YF-12A Final Mission


Thirty-one years ago this month, the 2nd and only surviving USAF/Lockheed YF-12A completed its final NASA flight research mission.  The flight brought to a close the 10-year period within which the YF-12A was employed as a NASA high-speed flight research platform. 

The YF-12A was the interceptor variant of the vaunted Lockheed A-12 Mach 3+ aircraft.  Armed with a quartet of Hughes AIM-47A air-to-air missiles, the YF-12A’s mission would be to intercept and destroy incoming Soviet bombers.  Lockheed proposed the A-12 variant as a cost-effective replacement for the defunct North American XF-108 Rapier.

 The YF-12A differed from the A-12 in that a second crew station was added for the AIM-47A Weapons Systems Officer (WSO).  The WSO operated the powerful Hughes AN/ASG-18  fire control radar which had a range on the order of 500 miles.  The YF-12A’s forebody chines were truncated back of the axisymmetric nose to accommodate the radar system.  Infrared (IR) sensors were installed on the leading edges of the shortened chines.

The Hughes AIM-47A missile measured 12.5 feet in length and 13.5 inches in diameter.  Maximum range of the 800-pound missile was in excess of 100 miles.  While the type’s intended maximum Mach number was 6, propulsion system development problems limited the demonstrated maximum Mach number to 4.  About eighty (80) AIM-47A missiles were produced.  Seven (7) of these rounds were test fired in flight.  All but one (1) was successful.    

Lockheed converted a trio of A-12 aircraft to the YF-12A configuration.  The YF-12A aircraft were assigned serial numbers 60-6934 (Ship 1), 60-6935 (Ship 2) and 60-6936 (Ship 3).  Ship 1 made the maiden YF-12A flight from Groom Lake, Nevada on Wednesday, 07 August 1963 with James D. Eastham at the controls.

Over the next eighteen (18) months, all three (3) YF-12A aircraft were put through performance flight testing at Groom Lake.  Ship 3 set a number of speed and altitude records on Saturday, 01 May 1965.  Included was the first air-breathing aircraft speed record in excess of 2,000 mph (2,070.102 mph) and a sustained altitude record of 80,257.86 feet above mean sea level.

USAF liked the YF-12A’s demonstrated performance capabilities.  Thus, on Friday, 14 May 1965, the service ordered ninety-three (93) units of the production YF-12A aircraft  known as the F-12B.  Congress approved the order and allotted $90M to get production going.  Unfortunately, United States Secretary of Defense Robert S. McNamara nixed the deal and cancelled the production of the F-12B.    

Recall that McNamara also cancelled the XB-70A and X-20A Dyna-Soar and was the genius who championed the ill-posed TFX multiservice aircraft concept.  He was also responsible for crafting the absurd rules of air war engagement that resulted in the inordinately large and unnecessary losses of American pilots in Viet Nam.  McNamara further cemented his status as the Bane of the U.S. Air Force with the F-12B production wave-off.

Following the F-12B cancellation, YF-12A flight testing by USAF continued through 1969.  One aircraft was lost along the way.  On Thursday, 14 August 1966, Ship 1 was severely damaged in a landing incident at Edwards AFB and never flew again.  Happily, the crew escaped injury.

In December of 1969, NASA initiated a flight research effort using YF-12A Ship 2 and Ship 3.  Over the next ten (10) years a wealth of aerodynamic, aero heating, structural and propulsion flight research data were acquired using these unique high-speed assets.  A great benefit in this regard was the type’s ability to sustain Mach 3+ flight conditions for periods up to 15 minutes per mission. 

YF-12A Ship 3 was lost on Thursday, 24 June 1971 when an inflight fire started due to a failed fuel line in the right-hand J58 turbo-ramjet engine.  The USAF crew of pilot Lt Col Ronald J. Layton and WSO Maj William A. Curtis attempted to recover the aircraft to Edwards AFB.  However, the fire quickly spread and forced the crew to abandon the aircraft.  They ejected safely and survived.  Ship 3 was making its 67th flight of the NASA YF-12A flight research effort at the time of its demise.

Following  Ship 3′s loss, Ship 2 flew the remainder of the NASA YF-12A high-speed flight research program.  It registered a total of 146 missions in that capacity.  On Wednesday, 07 November 1979, YF-12A Ship 2 departed Edwards AFB for its final destination; the USAF Musuem at Wright-Patterson AFB, Ohio.  The USAF crew consisted of pilot Col James V. Sullivan and USAF Museum Director Richard Uppstrom as the guy in back (GIB).

As a footnote to the current story, the USAF attempted throughout the 1950′s and 1960′s to develop and produce a Mach 3 interceptor.  Notable abortive attempts include the Republic XF-103 Thunder Warrior, the North American XF-108 Rapier and the Lockheed F-12B.  Doubtless, there have been failed black-world attempts as well.  The net result is that a Mach 3 interceptor has yet to grace the USAF production aircraft inventory.

Posted in Aerospace, History

The Lone MOL Flight

Forty-four years ago this month, a prototype of the USAF/Douglas Manned Orbiting Laboratory (MOL) was launched into Earth orbit.  It was the first and only orbital flight test of the military space station.

The Manned Orbiting Laboratory (MOL) was a United States Air Force (USAF) program to develop a military reconnaissance space platform in the 1960′s.  Using advanced optic, camera and radar systems, the MOL’s military astronaut crew would have the capability to determine the nature of other countries’ military spaceflight activities.  Of particular interest were the clandestine military activities of the Soviet Union and Red China.

Operational MOL missions were to be launched from Vandenberg Air Force Base (VAFB) on the California coast.  Doing so would provide a polar orbit capability.  The corresponding high orbital inclination meant that the MOL would overfly much of the Earth’s surface during a 24-hour period.  

The MOL Program was formally announced to the American public in December of 1963.  The prime contractor was the Douglas Aircraft Company (DAC).  The MOL was a large cylinder that measured 72-ft in length and 10-ft in diameter.  The MOL consisted of 5 segments; main cabin, auxiliary cabin, experiment module, equipment module and a propulsion stage.  MOL GTOW was approximately 32,000 lbs. 

Fixed atop the MOL was a variant of the NASA Gemini spacecraft known as Gemini B.  The crew would ride into and out of orbit in this vehicle.  Access to the MOL was via a small door built into the Gemini’s heat shield.  Once inside the MOL, the crew would doff their spacesuits and live in a “shirt-sleeve” environment.  MOL was to use a two-gas atmosphere (70% oxygen-30% helium).  A typical MOL mission was on the order of 30 days.

The Gemini-MOL combination was to be boosted into orbit by a Titan IIIC launch vehicle.  First stage propulsion consisted of a pair of solid rocket boosters and a liquid sustainer core.  Total lift-off thrust was about 1.84 million pounds.  Second stage thrust was on the order of 100,000 pounds.  The Titan IIIC third stage was the MOL transtage which produced 16,000 pounds of thrust.   

Seventeen (17) MOL astronauts were selected in three (3) groups from the military services.  MOL Group 1 (November 1965), MOL Group 2 (June 1966) and MOL Group 3 (June 1967) consisted of eight (8), five (5) and four (4) selectees, respectively.  None of these men ever flew a MOL mission.  However, seven (7) went on to fly on the Space Shuttle.   

On Thursday, 03 November 1966, the one and only flight test of the MOL Program took place.  Lift-off from Cape Canaveral’s LC-40 occurred at 13:50:42 UTC.  A Titan II propellant tank served as the MOL test article.  The previously-flown Gemini 2 spacecraft was employed as a representation of the Gemini B vehicle.  The lone MOL prototype flight test was unmanned.

During Titan IIIC ascent, the Gemini 2 spacecraft separated and executed a sub-orbital reentry.  The vehicle splashed-down in the South Atlantic Ocean near Ascension Island and was recovered by the USS La Salle.  Post-flight inspection of the vehicle’s heat shield hatch revealed that it came through the reentry intact. 

Meanwhile, the Titan IIIC launch vehicle successfully orbited the MOL prototype.  In addition, a trio of satellites that had accompanied the MOL mock-up was successfully injected into Earth orbit.  Thus, the first and only flight test in the history of the MOL Program was entirely successful.

Despite its game-changing mission, a successful flight test and its technical feasibility, the MOL Program never achieved operational status.  It was cancelled by U.S. Secretary of Defense Melvin Laird in 1969.  The cancellation came at a time when the country had invested heavily in the Apollo Program throughout the 1960′s, the Viet Nam War was escalating and unmanned satellite sensing technology was greatly improved.

The MOL cancellation was a real shot to the solar plexis of the American aerospace industry.  Coupled with the contemporaneous ramp-down of the Apollo engineering and development effort, American aerospace would never again see the breath and depth of financial investment it enjoyed in the 1950′s and 1960′s.

The lone surviving physical artifact of the MOL Program was the twice-flown Gemini 2 spacecraft.  It is on display today at the Air Force Space and Missile Museum at Cape Canaveral, Florida.

Posted in Aerospace, History

First Reusable Space Ship


Twenty-nine years ago this month, the Space Shuttle Columbia completed the second mission of the Space Shuttle Program.  Designated STS-2, the mission marked the first reuse of a space vehicle for manned orbital flight. 

America’s early manned spacecraft – Mercury, Gemini and Apollo - were single-flight vehicles.  That is, a new spacecraft was required for each space mission.  This was appropriate for meeting the aims of the early space program which concentrated on getting America to the moon before the end of the 1960′s.

The concept of space vehicle reusability came into vogue with the introduction of the Space Transportation System (STS).  The original goal of the STS was to provide frequent and routine access to space via a fleet of Space Shuttle vehicles.  For the STS to achieve economic viability, this meant flying a Space Shuttle once every two weeks.  History has shown that this projected flight rate was optimistic to say the least.

The Space Shuttle vehicle was ultimately configured as a 3-element system consisting of (1) a winged orbiter, (2) a  pair of solid rocket boosters (SRB’s) and (3) an external tank (ET).  Both the orbiter and the SRB’s were designed to be reusable.  The ET would be the only disposable element of the system since higher costs would be incurred in the recovery and refurbishment of this piece of flight hardware than in simply using a new one for each flight.

The Space Shuttle was designed to haul large payloads; on the order of 60,000 and 50,00 lbs into and out of orbit, respectively.  With a maximum landing weight of 230,000 lbs, the Space Shuttle Orbiter needed wings to generate the required aerodynamic lift force.  Wings were needed to satisfy the Orbiter’s 1,100-nm entry cross range requirement as well.

Following the successful first flight (STS-1) of the Space Shuttle Columbia in April of 1981, preparations began immediately to ready the Orbiter for its equally monumental second flight.  The STS-2 flight crew would consist of Commander Joe Henry Engle and Pilot Richard Harrison Truly.  STS-2 would be the first orbital spaceflight for both men.

On Thursday, 12 November 1981, the Space Shuttle Columbia lifted-off at 15:09:59 UTC from Cape Canaveral’s LC-39A.  Ascent flight was nominal and Columbia was placed into a 125-nm x 120-nm orbit.  At this point, Columbia became the first manned spacecraft to achieve Earth-orbit twice.  It was an extra special occasion for Richard Truly inasmuch as it was his 44th birthday. 

Engle and Truly anticipated 5-days in orbit with their orbital steed.  However, one of Columbia’s three fuel cells failed early-on and the mission was reduced to just over two days.  Nonetheless, the crew achieved 90 percent of the mission’s goals.  They even remained awake during a scheduled sleep period to exercise the new Canadian Remote Manipulator System (RMS).

On Saturday, 14 November 1981, Columbia and her crew successfully completed STS-2 by landing on Rogers Dry Lake at Edwards Air Force Base, California.  Main gear touchdown occurred at 21:23:11 UTC.  Joe Engle flew the entire reentry manually.  He holds the distinction of being the only pilot to manually fly a lifting space vehicle all the way from orbit to landing.  Engle completed a total of 29 Programmed Test Input (PTI) aerodynamic maneuvers in the process.

STS-2 was a monumental success.  Columbia became the first space vehicle to be reused for manned orbital space operations.  Other Orbiters would follow including ChallengerAtlantis, Discovery and Endeavor.  As of this writing, 132 STS missions have been flown.

As a footnote, Joe Engle went on to command one more Space Shuttle mission in 1985 (STS-51I).  He retired from the USAF in November of 1986.  Richard Truly served as Commander of STS-8 in 1983.  That mission featured the first night launch and landing of the Space Shuttle.  Richard Truly also served as NASA Administrator from May of 1989 to May of 1992.

Posted in Aerospace, History

First to Mach 6

Forty-nine years ago this week, the USAF/NASA/North American X-15 became the first manned aircraft to exceed Mach 6.  United States Air Force test pilot Major Robert M. White was at the controls of the legendary hypersonic flight research aircraft.

The North American X-15 was the first manned hypersonic aircraft.  It was designed, engineered, constructed and first flown in the 1950′s.  As originally conceived, the X-15 was designed to reach 4,000 mph (Mach 6) and 250,000 feet.  Before its flight test career was over, the type would meet and exceed both performance goals.

North American built a trio of X-15 airframes; Ship No. 1 (S/N 56-6670), Ship No. 2 (56-6671) and Ship No. 3 (56-6672).  The X-15 measured 50 feet in length, had a wing span of 22 feet and a GTOW of 33,000 lbs.  Ship No. 2 would later be modified to the X-15A-2 enhanced performance configuration.  The X-15A-2 had a length of 52.5 feet and a GTOW of around 56,000 lbs.

The Reaction Motors XLR-99 rocket engine powered the X-15.  The small, but mighty XLR-99 generated 57,000 pounds of sea level thrust at full-throttle.  It weighed only 910 pounds.  The XLR-99 used anhydrous ammonia and LOX as propellants.  Burn time varied between 83 seconds for the stock X-15 and about 150 seconds for the X-15A-2.

The X-15 was carried to drop conditions (typically Mach 0.8 at 42,000 feet) by a B-52 mothership.  A pair of aircraft were used for this purpose; a B-52A (S/N 52-003) and a B-52B (S/N 52-008).  Once dropped from the mothership, the X-15 pilot lit the XLR-99 to accelerate the aircraft.  The X-15A-2 also carried a pair of drop tanks which provided propellants for a longer burn time than was possible with the stock X-15 flight.   

The X-15 employed both aerodynamic and reaction flight controls.  The latter were required to maintain vehicle attitude in space-equivalent flight.  The X-15 pilot wore a full-pressure suit in consequence of the aircraft’s extreme altitude capability.  The typical X-15 drop-to-landing flight duration was on the order of 10 minutes.  All X-15 landings were performed deadstick.

On Thursday, 09 November 1961, USAF Major Robert M. White would fly his 11th X-15 mission.  The X-15 and White had already become respectively the first aircraft and pilot to hit Mach 4 and Mach 5.  On this particular day, White would be at the controls of X-15 Ship No. 2.  The planned maximum Mach number for the mission was Mach 6.

At 17:57:17 UTC of the aforementioned day, X-15 Ship No. 2 was launched from the B-52B mothership commanded by USAF Captain Jack Allavie.    Bob White lit the XLR-99 and pulled into a steep climb.  Mid-way through the climb, White pushed-over and ultimately leveled-off at 101,600 feet.  XLR-99 burnout occurred 83 seconds after ignition.  At this point, White was traveling at 4,093 mph or Mach 6.04.

On this record flight, the X-15 was exposed to the most severe aerodynamic heating environment it had experienced to date.  Decelerating through Mach 2.7, the right window pane on the X-15′s canopy shattered due to thermal stress.  The glass pane remained intact, but White could not see out of it.  Fortunately, he could see out of the left pane and made a successful deadstick landing on Rogers Dry Lake at Edwards AFB.

For his Mach 6+ flight, Bob White was a recipient of both the 1961 Collier Trophy and the Iven C. Kincheloe Award.  The year before, White had received the Harmon Trophy for his X-15 flight test work.  He would go on to fly the X-15 to a still-standing FAI altitude record of 314,750 feet in July of 1962.   For this accomplishment, White was awarded USAF Astronaut Wings. 

Bob White flew the  X-15 a total of sixteen (16) times.  He was one (1) of only twelve (12) men to fly the aircraft.  White left X-15 Program and Edwards AFB in 1963.  He went on to serve his country in numerous capacities as a member of the Air Force including flying 70 combat missions in Viet Nam.  He returned to Edwards AFB as AFFTC Commander in August of 1970.

Major General Robert M. White retired from the United States Air Force in 1981.  During his period of military service, he received numerous decorations and awards including the Air Force Cross, Distinguished Service Medal, Silver Star with three oak leaf clusters, Legion of Merit, Distinguished Flying Cross with four oak leaf clusters, Bronze Star Medal, and Air Medal with 16 oak leaf clusters.

Bob White was a true American hero.  He was one of those heroes who neither sought nor received much notoreity for his accomplishments.  He served his country and the aviation profession well.  Bob White’s final flight occurred on Wednesday, 17 March 2010.  He was 85 years of age.

Posted in Aerospace, History

Convair XFY-1 Pogo

Fifty-six years ago this week, the USN/Convair XFY-1 became the first Vertical Take-Off and Landing (VTOL) aircraft to successfully transition from vertical to horizontal flight.  The historic flight was piloted by famed Convair engineering test pilot James F. “Skeets” Coleman.

Motivated by World War II lessons-learned, the United States Navy began contemplating the feasibility of using VTOL aircraft for fleet defense in 1947.  A VTOL aircraft would combine the vertical  take-off and landing capabilities of a helicopter with the speed and agility of a fighter.  The operational advantage and flexibility derived from basing such an aircraft on non-aircraft carrier naval vessels were powerful allurements indeed.

In May of 1951, the Navy awarded contracts to Lockheed and Convair to develop and flight test an experimental VTOL aircraft.  The Lockheed offering was designated as the XFV-1 while Convair’s version became known as the XFY-1.  Both companies were to produce two (2) test aircraft each.  History records that each company would ultimately produce just a single copy of its respective prototype.

Convair nicknamed its VTOL aircraft Pogo after the Pogo Stick jumping toy popularized by an earlier generation of American youth.  Such appellation referred to the XFY-1′s tendency to bounce on its quartet of shock-absorbered landing gear at touchdown.   The similarity to one bouncing up and down on a spring-loaded Pogo Stick is obvious.

The XFY-1 Pogo measured 35 feet in length and had a wing span of nearly 29 feet.  The type had a GTOW of 16,250 lbs and an empty weight of 11,750 lbs.  Power was provided by a 5,500 hp Allison YT-40 turboprop which drove twin, 3-blade, 16-foot diameter contra-rotating propellers.  This propulsion system produced a maximum thrust of 17,000 lbs.

The Pogo was difficult to fly vertically in close proximity to the ground.  Prop-wash interaction with the aircraft and ground plane being the chief culprit.  Even more difficult was the transition from vertical to horizontal flight and back again.  It was particularly challenging to land the aircraft as the pilot had to look over his shoulder and “back down” to a landing.

The XFY-1 pilot sat in a seat that rotated to accommodate vertical and horizontal flight attitudes as appropriate.  Pilot cockpit entry was via a 25-foot auxiliary ladder.  Interestingly, the pilot was provided with a 25-foot rope for emergency egress during ground operations.

James F. “Skeets” Coleman was Convair’s project test pilot for XFY-1 flight tests.  Coleman began tethered flight testing of the aircraft on Thursday, 29 April 1954 at NAS Moffett Field, California.  Roughly 60 hours of tethered-flight testing took place within Moffett’s cavernous Hanger Number One.  With a ceiling height of 195 feet, the building provided ample room for initial XFY-1 vertical flight testing.

On Sunday, 01 August 1954, Coleman made the first untethered XFY-1 flight test in the vertical.  Following several more successful vertical take-off and landing trials, XFY-1 flight test activities were transferred to NAS Brown Field near San Diego, California.  There, Coleman intently practiced (making 70 flights overall) in anticipation of the first attempt to transition the XFY-1 from vertical to horizontal flight.

On Tuesday, 02 November 1954, with Skeets Coleman at the controls, the XFY-1 lifted-off in the vertical from Brown Field.  Coleman then carefully and skillfully transitioned the XFY-1 to horizontal flight for the first time.  In 21 minutes of horizontal flight, Coleman put the nimble XFY-1 through its paces.  The Pogo’s big Allison turboprop had power to spare as Coleman hit airspeeds well in excess of 300 mph.

When it was finally time to land the XFY-1, Coleman made a low altitude, minimum power approach and pulled into the vertical.  As the aircraft quickly ascended, the airspeed bled-off just as rapidly.  Near the top of the climb, Coleman advanced the throttle.  The XFY-1 hung in the cool autumn air on the thrust of its twin props alone.  The pilot then carefully descended from about 1,000 feet AGL and landed uneventfully.

Skeets Coleman made many more flights in which he demonstrated the Pogo’s VTOL capabilities.  However, USN interest in the VTOL concept in general and the XFY-1 aircraft in particular began to wane.  While the XFY-1 had indeed demonstrated the feasibility of VTOL flight, it also revealed the operational impracticality of such given the technology of the time.

The Achilles Heel of the Convair XFY-1 VTOL aircraft was the vertical landing phase.  The pilot just could not judge rate-of-descent accurately.  This was attributed partly to the fact that  he had to look over his shoulder throughout the descent.  In addition, XFY-1 throttle-induced lateral-directional handling qualities were poor and forced the pilot to work very hard at landing the aircraft even in low-wind conditions.         

Skeets Coleman made the last flight of the XFY-1 experimental aircraft on Thursday, 16 June 1955.  For his significant piloting efforts in successfully demonstrating the feasibility of the VTOL concept, he received the 1954 Harmon Trophy.  The lone Convair XFY-1 Pogo test aircraft survived the flight test program and is currently held in the historical collection of the National Air and Space Museum.

Posted in Aerospace, History