30 September 2010

The Skunk Works Make a Real Stinker: The Lockheed XF-90

In mid-1945 Lockheed responded to an Army request for proposals for an advanced jet fighter design. One of the stipulations of the Army RfP that was issued to the American aircraft industry was the use of off-the-shelf engine designs and despite this requirement, Lockheed submitted a design based loosely on the P-80 (later redesignated F-80) Shooting Star using their own advanced L-1000 axial flow turbojet which at the time only existed on paper. Though what at the L-1000 engine offered was a quantum leap over existing engine designs, the Army disqualified Lockheed's early submission. An alternate proposal with the General Electric J35 was offered, but it failed to offer any advance over the North American F-86 Sabre then in development. Kelly Johnson, head of the Lockheed "Skunk Works" that had successfully (and quickly) built the XP-80 prototype, decided that the design would be refined further and use two Westinghouse J34 engines. But quite presciently, Johnson realized that any engine would require an afterburner to achieve the desired performance levels. At the time one had not yet flown and Lockheed did much early work using the second XP-80 prototype to test various afterburner designs. 

By the fall of 1945 the Army's requirements specified what was called a "penetration fighter" that would have performance and a long range to escort heavy bombers deep into enemy territory. Lockheed submitted its refined design which would be come the XF-90, McDonnell submitted what would become the XF-88, and Convair had submitted a design that was later overturned due to political considerations after having been selected and instead Lockheed, McDonnell, and North American were asked to build prototypes, the North American design being what would become the XF-93 (based on the F-86 Sabre).

The original design was to have featured delta wings, but Lockheed's own wind tunnel testing didn't show the expected gains and what had been started on the delta wings had to be scrapped as the aircraft was redesigned with 35-degree swept wings, a sharp pointed nose and a swept-back empennage. In the summer of 1948 Lockheed's design was redesignated from XP-90 to XF-90. Unlike the success that came with the building of the XP-80 prototypes, the XF-90 wasn't able to fully benefit from the lean techniques used in the Skunk Works and as a result, compromises had to be made that resulted in the XF-90 being overbuilt and heavier than its original specification.

In fact, the XF-90 prototype was so heavy, the original Westinghouse J34 engines that were used that lacked the afterburner weren't enough to get the aircraft off the ground! RATO units had to be used for nearly all of the first seventeen flights unless the prototype was lightly loaded with little fuel. For most of 1949 Lockheed struggled with not just a woefully-underpowered fighter, but also one with a number of handling issues. By September of that year, Westinghouse finally delivered J34 engines with afterburners which helped somewhat to alleviate the anemic performance of the XF-90. The second XF-90 was the first to fly with the afterburning J34 engines and its performance was still an issue. With the use of afterburner, fuel consumption rose and large wingtip fuel tanks were added to the design that doubled the XF-90's range. Unfortunately, that also meant an increase in weight that exacerbated the aircraft's performance issues.

In the summer of 1950 the XF-90 was formally entered into the Penetration Fighter Evaluation Program and pitted against the McDonnell XF-88 and the North American XF-93. After the USAF evaluation of the candidate aircraft, the McDonnell XF-88 was declared the winner, but with the Korean War on the horizon, the USAF wanted the penetration fighters to be considered for the fighter bomber role. Despite McDonnell winning the competition, the Air Force felt that the modifications to the XF-88 would have cost too much and the overbuilt XF-90 was suggested as having the necessary structural strength for low-altitude air-to-ground missions. Despite a flurry of proposals to put the XF-90 into production as the F-90A, nothing ever resulted as the Air Force decided that buying more Republic F-84G Thunderjets filled the need more economically and at lower risk. In the Korean War, the F-84G proved itself ably in the ground attack role. 

With the end of the penetration fighter program, the XF-90 was formally canceled after an expenditure of just over five million dollars. The first XF-90 went to the Lewis Flight Propulsion Laboratory in Ohio where its eventual fate has been lost to history. The second XF-90 was used as a ground specimen in a series of nuclear tests in Nevada in 1952. In 2003, the National Museum of the United States Air Force recovered the hulk from Nevada test site and decontaminated it for display at the museum on the effects of nuclear testing. 

Amidst the many successes of the Lockheed Skunk Works and its iconic head, Kelly Johnson, the sleek looking XF-90 only looked fast and remains one of the company's more dismal missteps in aviation history. The winner of the penetration fighter contest, the McDonnell XF-88, would eventually be refined at McDonnell's own cost and would later win a production contract as the larger and more powerful F-101 Voodoo. 

Source: Experimental & Prototype U.S. Air Force Jet Fighters by Dennis R. Jenkins and Tony R. Landis. Specialty Press, 2008, p138-143.

28 September 2010

An American Astronaut Saves the A300 and Airbus

The first several years of Airbus' existence after the first flight of the A300 were miserable ones as orders slowly trickled in while the McDonnell Douglas DC-10 and the Lockheed L-1011 Tristar were racking up order after order from the world's airlines. Between the end of 1975 and May of 1977, Airbus failed to get even a single order for the A300. The joke at the factory at Toulouse was "Don't miss the last train out of town to Germany" in reference to the large number of German workers present. Part of the problem was the recession in the wake of the 1973 Yom Kippur War and the Arab oil embargo on the West. But a big part of the problem was the Airbus was an upstart facing the powerful sales machines of Boeing, McDonnell Douglas, and Lockheed. For a lot of the world's airlines, buying the A300 simply wasn't on their radar screen. The program was in jeopardy and the member nations of the Airbus consortium were getting restless as debates continued on whether they'd misread the market or not. 

But all of that was to change with the passage of airline deregulation in the United States. The world's largest airline market in terms of passengers moved, breaking into the US market was a key goal for Airbus and one of the main reasons that they had sought the advice of Frank Kolk at American Airlines back in the late 1960s when the design was still being formalized. With deregulation, free market forces now determined routes, fares and frequencies on the US East Coast, one of the dominant legacy carriers was taking a severe beating on its prized routes between the US Northeast and Florida. Eastern found itself embroiled in a bruising market fight with National and Delta. Eastern was already operating the Lockheed Tristar on the routes and word got to Airbus that they were interested in a 200-seat aircraft with better operating economics than the Tristar. With only two engines, the fuel burn on the A300 was already lower than that of the Tristar and with 2/3 the seating capacity, Airbus felt they had an ideal product to meet Eastern's needs. 

Eastern had been in discussions with Boeing, Lockheed, and McDonnell Douglas already but Eastern's financial position in the wake its battle with National and Delta meant it needed an aircraft with better economics than the Tristar and it needed them at a sweet deal. On the day of the final sales presentations by the all the manufacturers, Airbus was slotted in to present to Eastern's management and its president, former Apollo 8 mission commander and astronaut Frank Borman. Airbus' team gave its presentation and then offered a sweetener- they had four "white tail" aircraft (completed A300s that had no buyers) that Eastern could immediately lease for a four month trial. If they were happy with the aircraft, they could order more. Borman sent word to Toulouse after deliberations "Congratulations, you've got a blue-eyed baby." It was the breakthrough that saved the A300 program- after a very successful trial, on 6 April 1978, Eastern ordered 23 A300s with options on more. But the bold move by Borman upset many. 

The Department of Commerce and some in the US government demanded an explanation from Borman. After all, political influence several years earlier was successful in steering Western Airlines away from the A300. Borman was accused of being anti-patriotic depsite his military and space records. Charles Forsyth, the VP for McDonnell Douglas, even angrily called Borman directly and accused him of being unpatriotic. Borman reportedly asked Forsyth what brand of luxury car he drove, knowing the answer wasn't American. Borman explained that the most valuable part of the Airbus A300 were its engines and those engines were GE engines along with a large amount of American content from thousands of subcontractors. Congressional hearings were even held at Boeing's urging with accusations of predatory pricing by Airbus to make the sales- many of the same arguments being made these days in Airbus versus Boeing sales fights. Regardless, it was a major achievement for the young Airbus Industrie and would become legend throughout Europe how an American astronaut saved the A300 program. 

26 September 2010

The Boeing 247 Flying Laboratory of United Air Lines

United Air Lines' legendary president William "Pat" Patterson listed his corporate goals in what he called his "Rule of Five"- safety, passenger comfort, dependability, honesty, and sincerity. To Pat Patterson, the goal of safety was the most important that he asked each and everyone one of his employees to strive for above all else. Despite the rapid advances in aviation technology in the 1920s and 1930s, airline flying was nowhere near the routine that we today take for granted. Patterson believed that the industry as a whole would benefit from investing in technology that increased aircraft safety. His first tangible commitment to that goal came in 1929 when the United Communications Laboratory based on the second floor of a hangar at Chicago Midway was established as the airline industry's only communications laboratory. One of the first developments from United Air Lines engineers assigned to the Communications Lab was a practical two-way radio for aviation use. 
In 1937, one of United Air Lines' Boeing 247Ds, NC13365, was pulled off the line and assigned to the airline's laboratory at Chicago Midway. This particular aircraft also happened to be the last Boeing 247 built. Re-registered as NX13365, the interior was fitted with test benches to hold equipment and the ceiling hat racks were modified to carry wire bundles to and from the various test equipment being used. Nicknamed the "Flying Lab", the Boeing 247D made its first flights for what became the United Flight Research Lab (as its efforts moved beyond communications and into general flight safety) the standard all-over gray color used on United's 247 fleet at the time. Before long, however, NX13365 was repainted in an attractive white and red scheme with "Flight Research" titles on the fuselage. 

The first assignment flown by NX13365 was the problem of static electricity build-up on the airframe. Particularly during bad weather, the static build-up on the airframe could reach levels sufficient to interfere with the communications and navigation equipment. Several Boeing 247s were lost due to accidents directly attributable to static build up on the airframe during flight. Working together with the Bendix Radio Corporation, NX13365 would log over 25,000 miles of flying developing a practical static "suppressor". A long wire extended from the tail that drew the static charge away from the airframe and dissipated it harmlessly. A resistor was part of the wire and a small waxed cup at the end of the wire kept it deployed in flight. Today we know these wires as the static wick dischargers on the wings and tail of modern aircraft. The first static dischargers were five foot long wires and true to his word, Pat Patterson had them fitted on every aircraft in the United fleet and shared the his lab's findings with the industry. 
NX13365 was also used for the development of what the lab called a "terrain clearance indicator". With many crashes at the time due to CFIT in poor weather (controlled flight into terrain), United's engineers worked with Western Electric and Bell Telephone to create the first radio altimeter which provided the pilots constant updates of the relative height above the ground. If the aircraft descended too low, a red light on the radio altimeter came on, alerting the flight crew. The first public demonstration of the radio altimeter was conducted on a flight above New York City that continued north over the Hudson River and over the Palisades. Following the completion of tests of the radio altimeter, again and true to his word, Pat Patterson had radio altimeters installed on everyone of United's aircraft and as he did with the static discharger, shared the findings with the rest of the industry. 

Before NX13365 was retired, United's engineers also developed an instrument landing system as well as a terrain-viewing television system in cooperation with the US Army Air Corps and also trialled different antenna configurations. In October 1945, United modified the aircraft back to passenger configuration and sold it to LAMSA (Lineas Aereas Mineras S.A.), a Mexican airline that United had invested in back in 1942. After flying with LAMSA for two years as XA-FIH "Estado de Sinaloa", it passed through several Mexican owners before ending up with an air taxi service that crashed the aircraft in Mexico City in 1952. 

Source: The Boeing 247: The First Modern Airliner by F. Robert Van Der Linden. University of Washington Press, 1991, p155-158.

23 September 2010

Hatching the Grumman Goose

In the fall of 1936 Grumman Aircraft was rapidly expanding having proven itself capable of producing fast advanced Navy biplane fighters that were set the standard for toughness during carrier operations. The company had just broken ground on its Bethpage plant on Long Island that would be its long-time home right on up to the production of the F-14 Tomcat. With the business of the United States Navy secure, Leroy Grumman and the founders of the company decided it was time to diversify by entering the civil market with their first aircraft designed for the commercial market, the Grumman G-21 Goose, which also would be Grumman's first monoplane design as well as it's first twin-engine aircraft. The Goose drew upon the company's experience with amphibians (all the founders of the company as well as Leroy Grumman had worked previously with Loening Aircraft on that company's amphibian designs) as well as its work on the lightweight floats added to the Navy's O2U Corsair biplanes and the Navy's JF Duck utility seaplane. 

While Grumman's team was beginning early design work on what would become the Goose, a group of ten wealthy Long Island businessmen and avid sportsmen led by New York businessman Wilton Lloyd-Smith, formed a syndicate to look at the possibility of having a private aircraft built to their specifications. Since the members of Lloyd-Smith's group all lived on waterfront estates on Long Island, their aircraft would have to be a seaplane that would allow them to commute back and forth between the Wall Street waterfront and their Long Island estates. Since some of the members didn't have waterfront property, the aircraft would have to be amphibious as well. With their needs in hand, they consulted with Grover Loening, who at the time was the only prior designer of civilian amphibians with his 1920s' vintage Air Yacht. At the time, Loening was long out of business for himself having sold his company to Keystone Aircraft and was working as a consultant as well as an investor in Grumman Aircraft. Loening reviewed the syndicate's needs and created a preliminary design that was a twin-engine, high-wing amphibian. 

It was here where Loening's design for the syndicate and the preliminary design work at Grumman crossed paths. Perhaps it wasn't coincidence as some of the members of the syndicate as well as Leroy Grumman and one of the other founders of his company were all members of the same country club on Long Island, but any such record has been long lost to the mists of history. When Loening was asked by the Lloyd-Smith who would he would recommend to build their design, without hesitation Loening pointed the way to Leroy Grumman's office in Bethpage. It was a happy combination- ten of the wealthiest Long Island businessmen willing to pay for the plane they wanted and Grumman, eager to enter the commercial market, with a ready-made order for 10 aircraft. 

In addition to Wilton Lloyd-Smith, a prominent New York lawyer, the other members of his syndicate who ordered the first production versions of the Grumman Goose included Henry S. Morgan (founder of Morgan Stanley), Marshall Field (of the department store fame), E. Ronald Harriman (philanthropist and investment banker), C.W. Deeds (head of United Aircraft, predecessor to Pratt & Whitney), Robert McCormick (owner of the Chicago Tribune), Boris Sergievsky (head test pilot for Sikorsky Aircraft) and C.V. Whitney (one of the founders and investors of Pan American Airways). With such prominent businessmen ordering the Grumman Goose, the project was accorded top priority and the prototype first flew on 31 May 1937. With a few adjustments and modifications, the first Grumman G-21A Goose was handed over to Wilton Lloyd-Smith on 3 July 1937 for a price of $60,000. 

The Goose was an immediate success and the need for more capital to expand the Bethpage production line for the aircraft resulted in Grumman registering with the Securities and Exchange Commission for the public sale of company stock and listing on Wall Street. The connections made with Lloyd-Smith's syndicate in bringing the Grumman Goose to fruition paid off handsomely for Leroy Grumman's small company with hundreds of G-21s built for both private owners, airlines and military air arms worldwide. The sales of the Goose helped Grumman invest heavily in its next Navy carrier fighter which first flew as a prototype in 1937. The XF4F-2 would later become famous during the Second World War as the F4F Wildcat. 

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p92-101.

20 September 2010

The Bell RP-63 Pinball

As the strategic bombing campaign over Germany built up in the spring of 1943, losses over the skies of the Reich began to mount as mission momentum increased over the course of that summer. While the ever-present flak was a significant threat to the B-17 Flying Fortresses and B-24 Liberators of the US Eighth Air Force based in the UK, it was the fighters of the Luftwaffe that were mauling the formations. From June into the autumn, losses were mounting and doubts were starting to be raised on the operational wisdom of daylight strategic bombing. The breaking point came on 14 October 1943 with the second attack on the ball-bearing plants at Schweinfurt, Germany. Already bruised from a vicious mauling at the hands of the Luftwaffe on the first raid on the Scweinfurt (which was attacked along with Regensburg on 17 August 1943 with the loss of 60 bombers), of the 291 B-17s sent on the mission, 77 bombers were lost and 122 were damaged. The day was named "Black Thursday" for having the highest number of crewmen lost on a single USAAF mission- 590 killed, 65 taken prisoner. Deep penetration missions of Germany were suspended until February 1944 when the long-range P-51 Mustangs arrived. 

But warnings were raised as early as 1942 stateside when Major Cameron Fairchild of the USAAF sought ways to improve the aerial gunnery skills of the men who manned the defensive positions on the heavy bombers. The techniques of training at the time were fairly basic, ranging from skeet shooting to firing at towed targets. Fairchild surmised the best aerial gunnery training would consist of being able to fire live ammunition at an actual fighter aircraft. His first task was to develop a bullet that had the same characteristics as a 30- or 50-caliber round but would splinter harmlessly on impact. Working with researchers at Duke University, the University of Michigan, and the Bakelite Corporation (one of the pioneering manufacturers of plastics), Fairchild and his team came up with a frangible bullet that was weighted with powdered lead to give it the proper weight and density. 

Fairchild proved to be willing to circumvent the usual Army bureaucracy to promote his ideas. Instead of working through the usual Army weapons development channels, he teamed up with academics to validate his ideas. Fortunately, the heavy losses of 1943 showed that aerial gunnery skills were lacking and Fairchild's frangible training bullets gained traction with the USAAF. He then selected the Bell P-63 Kingcobra as the target aircraft. As it was a type not used by front-line USAAF units, it was easily available. The P-63, designated RP-63, was given 1-inch thick armored glass with special armor in vulnerable areas. Sensors underneath the RP-63 registered hits and lights on the spinner and on the fuselage would light up, giving rise to the name "Pinball". 

Beginning in early 1945 RP-63 Pinballs would fly attack profiles against bombers with student gunners before they were assigned to a combat unit. A training B-17 might have 12 student gunners each having 2,000 rounds of Fairchild's special frangible ammunition to fire at the Pinballs. The Pinball pilots, flying RP-63s that were painted either dayglo orange or yellow, flew 2-3 missions a day from bases throughout the United States. Minor damage was easily repaired on the flightline but the Achilles heel of the Pinball was the wingroot air ducts that provided cooling air to the mid-fuselage mounted Allison V-1710 liquid-cooled engine. If a frangible bullet got into the duct, the fragments could damage the cooling system, resulting in an overheating engine and a mandatory deadstick landing or a bailout by the RP-63 pilot. 

A total of 300 P-63s were converted to the RP-63 Pinball configuration. Some aircraft also trained B-29 Superfortress gunners, but by 1947, the Pinball program was wound down and the last aircraft retired. Much of the early demise of the program came with the introduction of the centralized gunner control system in the Boeing B-29 Superfortress where analog systems provided the necessary lead and tracking for the gunners which used sights that remotely operated the turrets. Targets could be handed off from one gunner's sight to another and it made aerial gunnery training obsolete. The second factor in the demise of the Pinball program came with the gun-laying radar that was first introduced on the tail cannons of the Convair B-36 Peacemaker. Radar simplified tracking and accurately shooting at target aircraft. But the Pinball program lives on as an unique wartime solution that undoubtedly did its part to hasten the demise of the Axis in the Second World War.

Source: Air & Space Smithsonian, November 2010, Vol. 25, No. 5. "Just Shoot Me: In World War II, P-63 pilots had to learn to take it- and not take it personally" by James Dunaway, p50-53. RP-63 model by Scott Van Aken.

18 September 2010

The Difficult Birth of Laker Skytrain

On 8 February 1966 when Freddie Laker formed Laker Airways, he already had an established reputation as an aviation entrepreneur, having already established his name with the maintenance and overhaul company Aviation Traders and with the independent airline British United Airways (BUA). In the very beginning, using loans and financing, Laker bought a pair of used Bristol Britannias from BOAC and three brand-new BAC One-Elevens and started flying services in July 1966 under a contract with Air France while entering the package holiday market. By the following year Laker introduced time-charters which committed tour operators to contacts with Laker that guaranteed him a fixed number of flying hours per year to carry tour operators' customers to holiday destinations in the Mediterranean. His innovative contracts allowed him to sell seats on his One-Elevens two years before he took delivery of the aircraft. In 1969 Laker purchased two used Boeing 707s and with other European independent carriers, began trans-Atlantic services at low prices to travel groups. 

At the time these travel groups were set up for a variety of reasons that often were simply to evade the high prices on established airlines across the Atlantic. At the time there were strict rules governing the carriage of such passengers and the charter airlines were held legally responsible to verify the authenticity of a group's operation. Since the fares were strictly regulated between the United States and the UK at the time, an airline that sold seats to non-members of such groups could face heavy fines. Despite Laker employing lawyers to take sworn statements from his passengers, he still was accused of circumventing the rules and was threatened with heavy fines that could have shut down his airline. 

Laker became an outspoken critic of what he felt was a protected market with the implicit collusion of the regulatory authorities. He decided to do away with advance booking and the need for groups to fly between the US and the UK for reasonable prices. The Skytrain was born- all a passenger had to do was show up at the airport with a valid passport, buy a ticket and board the aircraft. Laker's inaugural prices were set at approximately US$60, about 25% of the lowest advance fare on an IATA carrier. When Laker applied to the British Air Transport Licensing Board (ATLB) in 1971 for the rights to operate services between New York and London, both the British and US governments along with IATA and its member airlines immediately protested. In 1971 14 million passengers a year were crossing the Atlantic by air and Laker believed he could grow the market by another 2 million easily with his pricing structure and no-frills service. 

The ATLB rejected his application and also rejected his subsequent appeal. However, Laker's efforts at launching service caught the attention of the newly-formed Civil Aviation Authority (CAA) which was established in 1972 to regulate all aspects of UK civil aviation. The CAA was empowered to take over several regulatory areas that were previously the responsibility of the ATLB and one of its first acts was to overturn the rejection of Laker's application and offered him traffic rights at London Stansted. Laker wanted to operate out of London Gatwick which had rail connections to central London where Laker's main ticket offices were located. In 1972, Stansted was a small airport that lacked good ground transport links to central London. Despite this, however, the CAA designated Laker as a national flag carrier so that the airline could not be blocked by the US government. 

Laker went ahead and ordered two McDonnell Douglas DC-10s which he first put into service on his Mediterranean holiday services with the intent of using them on his innovative Skytrain services. However, in 1973, the US Civil Aeronautics Board (CAB) refused to grant Laker traffic rights for the United States on the basis that he was still in violation of the old rule regarding travel groups flying across the Atlantic. Laker was fined despite a lack of proof that he had violated the rules back in 1969. After a lengthy series of discussions, by 1974 the CAB decided to retract the fines and approved his applications for services to the United States. However, under pressure from the US airlines that held a significant share of the trans-Atlantic market (led by TWA and Pan Am), President Nixon refused to approve the application. Laker responded by threatening lawsuits against the US and UK airlines that were lobbying the refusal of his application. Under pressure from BOAC, the CAA eventually canceled the license for Laker Skytrain. 

This started a long public debate that by 1976 the UK Parliament's House of Lords called on the government to approve the Laker license on the basis that it was in line with public opinion of the day. The UK courts agreed with the House of Lords after Laker proved that the British government and the CAA were violating their own regulations in rejecting his license application. In the United States, though, Laker found an ally in President Jimmy Carter who was an advocate of deregulation (Carter would later sign the Airline Deregulation Act in 1978) and readily signed off on the US regulatory application to allow the Laker Skytrain to begin services. With victory in the UK courts in hand and victory in the United States with the help of President Carter, the first Laker Skytrain flight departed London Gatwick for New York JFK on 26 September 1977. Freddie Laker himself was aboard that aircraft which had been christened "Eastern Belle". His second DC-10 was christened "Western Belle". 

Source: Airliner Classics (in association with Airliner World), November 2009. "Sir Freddie Laker: The Man Who Gave Us Skytrain" by Bob Bluffield, p81-83.

16 September 2010

The First USAF Recon Missions in SE Asia

Following the partition of Vietnam in 1954, North Vietnam increased its support of not just the Viet Cong insurgency in the south but also provided support to the Pathet Lao insurgency in Laos. With the increase in activity of the Pathet Lao in the latter half of the 1950s, the Laotian government in Vientiane needed more information on the disposition and activities of the insurgents but the air arm of the nation lacked any sort of reconnaissance capability. As a result, the Vientiane government turned to the United States for assistance. At the time, the international commission (the ICC) that was overseeing the partition and planned reunification of Vietnam had strict rules about the activity of combat aircraft over Laos. So the first efforts consisted of a camera-equipped Douglas C-47 that was "assigned" to the US air attache in Saigon and Vientiane. As the C-47 flew between the two cities it was "assigned" to, it would fly over suspect Pathet Lao enclaves. This continued until February 1961 when the aircraft got shot down in the highlands in the northern part of Laos. 

As a result, President John F. Kennedy asked for more effective measures to be put in place to keep an eye on Pathet Lao activities. In April of that year, the Pacific Air Forces (PACAF) asked for volunteers from the two McDonnell F-101 Voodoo squadrons in the area, the 15th TRS at Kadena AB and the 45th TRS at Misawa AB. The recon pilots had to have recent Lockheed T-33 experience. Two pilots, Captain Bob Caudry and Lieutenant Fred Muesegaes, volunteered and were flown to Clark AB, Philippines, the headquarters of PACAF, to begin briefings of their top secret mission code named "Operation Field Goal". 

Operation Field Goal was made up initially of the two Voodoo pilots, five enlisted men, a crew chielf, and an additional officer to command the operation. A single Lockheed RT-33 was assigned to the project. The RT-33 was a hybrid of the T-33 trainer with the camera nose of the RF-80 Shooting Star. With an uprated jet engine and an additional fuel tank in place of the rear seat, Operation Field Goal was then moved from Clark AB to RTAFB (Royal Thai Air Force Base) Udorn in the northern part of Thailand, a short hop from the Laotian capital of Vientiane. Udorn would later in the Vietnam War become and important USAF base that would become home to several F-4 Phantom squadrons, but in 1961, Udorn hadn't changed much from its days as a Japanese Army Air Force base in World War 2. The only navaid at Udorn was a low-powered radio beacon with a range of about 25 miles, and on arrival, the RT-33 had to buzz the main runway to drive water buffalo away. 

A Marine detachment provided fuel and also built a tent city at Udorn (the first US presence at this base aside from the irregular operations of CIA-run Air America). Both Caudry and Muesegaes developed their own procedures for operating the RT-33 from the primitive base, right down to their own approach procedures for use in bad weather. A US Military Advisory Group in Vientiane tasked the RT-33 missions and at the end of each flight, the film was flown by an Air America helicopter to Vientiane for development and analysis. The pilot on that mission often accompanied to film to assist the photo-interpreters. 

Captain Bob Caudry flew the first Operation Field Goal mission on 24 April 1961, first overflying the Plain of Jars at 20,000 feet before making a low level run at 200 feet of a major road in an insurgent-held area of Laos. A total of sixteen missions with good intelligence were flown until 10 May 1961 when the ICC demanded the flights over Laos stop. Given the primitive nature of the RTAFB Udorn at the time and the grueling nature of the recon missions, Operation Field Goal moved to Don Muang Airport in Bangkok with plans of resuming the missions from there once the ICC lifted its ban. The ban did get lifted finally on 9 October 1961 and the Field Goal missions resumed, this time flying from Bangkok northward to Laos. Upon return to Bangkok, the RT-33 was then flown by non-recon pilots to deliver the aircraft and its film to the photo-analysts who were no longer in Vientiane but moved to RTAFB Udorn. On 5 November 1961 the last Field Goal recon mission was flown and all subsequent reconnaissance missions were now assigned to a detachment of four McDonnell RF-101C Voodoos that were assigned to Tan Son Nhut Airport in Saigon under Operation Pipe Stem. 

Subsequent reconnaissance efforts were now flown by regular USAF units, but the work done with that RT-33 resulted in the RT-33 being marketed by Lockheed to foreign air forces needing an inexpensive jet reconnaissance capability. 

Source: Voodoo Warriors: The Story of the McDonnell Voodoo Fast Jets by Nigel Walpole. Pen and Sword, 2007, p159-165.

13 September 2010

Taiwan's Secret Recon Voodoos

The Second Taiwan Strait Crisis occurred in 1958 when artillery units of the People's Republic of China bombarded the Nationalist islands of Quemoy and Matsu in a bid to retake them from Taiwan. In a bombardment that began in August of that year, nearly 450,000 shells were fired at the two Taiwanese islands in a standoff that also saw the first use of the AIM-9 Sidewinder when Republic of China Air Force (RoCAF) F-86 Sabres engaged PLAAF MiGs over the Taiwan Strait. During the crisis, US naval units were in the area to protect sea lines of communication from Taiwan to the two island outposts. As the crisis ended after 44 days in a stalemate, the US government decided that it needed more information on the disposition of Chinese forces on the PRC side of the strait. Some information came from RB-69 flights by Taiwanese crews and later clandestine P-3 Orion overflights also took place. But the RoCAF's reconnaissance F-86 Sabres and the RB-69s were increasingly vulnerable to improving Chinese defenses on the mainland. In November 1959, the USAF started Operation Boom-Town, a secret effort to utilize the much faster McDonnell RF-101 Voodoo in high speed, low level overflights of the mainland. 

Chiang Kai-Shek authorized the formation of the 4th Composite Reconnaissance Squadron (CRS) at Taipei AB in Taiwan. Initially operating Republic RF-84F Thunderflash jets, the pilots selected for the 4th CRS were the veritable "cream of the crop" of the RoCAF. The USAF's 15th Tactical Reconnaissance Squadron (TRS) based at Kadena AB in Okinawa was selected to provide material support and training for the 4th CRS to convert to the RF-101 Voodoo. The first group of RoCAF pilots trained at Okinawa under conditions of great secrecy. In 1964 the 4th CRS completed its transition to the RF-101 Voodoo and aircraft were flown directly from the 15th TRS' flightline to Taiwan, whereupon they were immediately hangared and repainted in RoCAF markings. Officially the 4th CRS was an all-Taiwanese operation, but the USAF maintained an advisory presence at the RoCAF base, being officially designated as "Detachment 1, 13th Air Force, Shaw AFB, South Carolina, Taipei" (Shaw AFB being the homebase of all USAF reconnaissance Voodoo operations). Pilots and maintenance crew from the 15th TRS at Kadena were rotated secretly back and forth to work with the 4th CRS to keep the Voodoos there flying on missions over mainland China.

Officially the Taiwanese government stated that the Voodoos were purchased to maintain surveillance capability around the waters of Taiwan, but the RoCAF Voodoo pilots frequently trained in air-refueling with USAF KB-50s deployed to the area. The RF-101 already had an impressive internal fuel capacity that gave it an impressive range for a Century-series jet. Air-refueling simply gave the RoCAF pilots the range to reach targets deep inside the mainland.

The RoCAF Voodoo overflight program ended in 1970 with the possible shootdown of one RF-101 over the mainland, quite an impressive record given the speed at which the Taiwanese pilots converted to the Voodoo and the number of reported overflights conducted. Most of the Voodoos were returned to the United States, but one remains on static display in Taiwan.

Source: Voodoo Warriors: The Story of the McDonnell Voodoo Fast Jets by Nigel Walpole. Pen and Sword, 2007, p105-106.

12 September 2010

Robin Olds and the Nuclear Voodoos

When SAC lost interest in the McDonnell F-101 Voodoo as a bomber escort, the Tactical Air Command (TAC) saw potential in the big fighter as a tactical nuclear bomber given its large fuel capacity and solid low-level stability. With the support of the commander of the US Air Forces Europe, General Frank Everest, and the USAF Vice-Chief of Staff, General Curtis LeMay, the single-seat F-101A and F-101C Voodoos were assigned to the 81st Tactical Fighter Wing in the UK at the twin bases in Suffolk at RAF Bentwaters and Woodbridge. There the Voodoos replaced the nuclear-capable Republic F-84Fs previously based there that were assigned targets in the East Germany, Poland, and the Baltic republics. Because of the nuclear delivery role of the 81st TFW, the wing tended to have more senior officers as pilots than other USAFE fighter wings of the time. Voodoos on "Victor Alert" were fueled and armed with a single tactical nuclear bomb on the centerline station between the two external fuel tanks. The 81st TFW began its nuclear alert duties with the F-101A/C at the end of 1958. 

Because of the nuclear role of the 81st TFW, many of the pilots assigned would later become generals within the USAF in their careers. In August of 1963, two famous USAF pilots came to the 81st TFW to assume command. Colonel Robin Olds, already an ace from the Second World War and Korea became the wing commander and Lt. Colonel Daniel "Chappie" James would be his Director of Operations. Men of the 81st TFW fondly remembered them as "Blackman and Robin". 

The choice of Olds to lead the wing was surprising to many given Olds' extensive background in air combat. Some even thought him unsuitable to command a tactical nuclear bomber wing. But his enthusiasm, skill, and reputation endeared him to the men of the wing and Olds surprised even his harshest detractors. Olds selected an F-101 with a serial number ending in "001" because, as he put it, "The boss should have Balls 1 as his personal mount." The morale of the unit was the utmost importance to the command staff at USAFE, which may have been the reason Robin Olds was selected to command the unit. The reason was simple- during a time of war, the Voodoos of the 81st TFW would have to fly in low and fast across the Iron Curtain to drop nuclear bombs on tactical targets in the rear flank areas of the Warsaw Pact's immense armored forces in East Germany. The defenses along the way were already dense and the Voodoos had no onboard ECM systems like SAC's bombers did. They would rely on speed and penetration altitudes as low as 50 feet to reach their targets in even the worst weather using the radars that had been upgraded to provide ground mapping functions. Many of the targets were beyond the combat radius of the Voodoo and the men were told they'd refuel from KB-50 tankers over the North Sea, but in a war, many knew that the missions would be one way with little chance of safe return to the UK. 

Knowing their assigned mission was one-way at best, having Olds as their commander was key to morale. Not only did Olds relish in the challenge of commanding the 81st TFW which was nothing like he had done before, he was eager to show the pilots the strengths of the F-101 Voodoo at low-level. Olds worked his man hard and had the Voodoos modified with one of the 20mm cannon being removed to make room for TACAN equipment to help with training missions. Olds set up an intensive series of training missions for his pilots and it wasn't unusual for a pilot sitting Victor Alert to be scrambled in an evaluation of his performance. Olds' rigorous training regimen no doubt would have made even Curtis LeMay proud. 

In 1964 the 81st TFW was notified that they would be soon transitioning to the McDonnell F-4C Phantom and would have start training for close air support missions. Though the Voodoo was far from ideal in CAS roles, Olds nonetheless trained them in CAS to prepare them for the transition to the Phantom which did have a CAS role for the USAFE and NATO. In order to keep the morale of the wing up, Olds set up an aerobatic unit to showcase the F-101's capabilities with four formation aircraft and one solo aircraft. Olds believed even the big Voodoo could be maneuverable if handled properly and the team trained in addition to their regular training duties. Olds, however, in his often maverick style, set up the team on his own accord without consulting his superior officers and his impending promotion to General along with a planned citation for his work in leading the 81st TFW were immediately scuppered. Olds was reassigned to a non-flying staff position as punishment for starting an aerobatic team. 

Only nine months elapsed before Colonel Olds was flying again, this time he was in Arizona converting to the F-4 Phantom. Olds would fly as much as three times a day to understand the quirks and advantages of the Phantom and found himself being called upon again to raise morale for another Air Force unit, this time the 8th Tactical Fighter Wing "Wolfpack" at RTAFB Ubon in Thailand which was suffering losses at the hands of North Vietnamese MiGs. During his tenure with the Wolfpack at Ubon, Olds ordered that no Voodoo reconnaissance pilot should have to buy his own drink at the officers' club at the base!

Source: Voodoo Warriors: The Story of the McDonnell Voodoo Fast Jets by Nigel Walpole. Pen and Sword, 2007, p119-131.

08 September 2010

How American Airlines Shaped the A300

In 1966, Sud Aviation and Breguet of France signed an agreement to cooperate with fellow French aircraft company Nord Aviation and British manufacturer Hawker Siddeley on a medium-range twin-aisle widebody aircraft with two engines tentatively designated HBN100. French President Charles De Gaulle asked Roger Beteille, an experienced technical manager who was the head of Alcatel Space, a French space systems company, to head the new joint venture. Beteille was one of the few French aeronautical managers who was fluent in English as well and highly regarded by the Hawker Siddeley team. For the next year, Beteille honed the HBN100 design to reflect the European marketplace as well as to accommodate the delicate political aspirations of each of the partners in the program. Size, capacity, range and even engine options were hammered out.

By 1967 Beteille was aware of the coming widebody competition in the United States with the McDonnell Douglas DC-10 and the Lockheed L-1011 Tristar. Both aircraft were trijets whereas the HBN100 design would be a twin jet of slightly smaller size. Rolls-Royce was already working with Lockheed to launch the RB.211 engine for the Tristar whilst working on the proposed RB.207 engine for the HBN100. At the time, the HBN100 design was larger than what it would be come as the A300 and Rolls-Royce was investing more time and energy in getting the RB.211 to market than the RB.207, something that troubled Beteille (it would also ultimately lead to Great Britain pulling out of the Airbus consortium). In a master stroke, Beteille convinced the partner nations to accept a smaller design that could use the same engines as were being developed for the Lockheed Tristar (the Rolls-Royce RB.211) and McDonnell Douglas DC-10 (the General Electric CF6). By getting the partners to agree to a smaller design, Beteille insured that Rolls-Royce wouldn't delay the program by dragging its feet on the more powerful RB.207 engine. Ultimately in 1969 Rolls-Royce abandoned development of the RB.207, so Beteille's decision was a prescient one. 

With the Tristar and the DC-10 flying first, the engines could be debugged and by the time what would become the A300 first flew, the engine choices would be operationally mature. It was a master stroke that saved the A300 at its most nascent stage. But Beteille was no gambler and deliberate in his calculations to keep the program moving. He often told his associates that it would be necessary to understand the American market as it was the biggest passenger market in the world. If Beteille's aircraft was going to be a success, they needed to make it in the United States as well. The airlines of the United States at the time were the operational envy of the world and Beteille decided he needed to meet with both United and American, as both airlines were known for the technical expertise and operational efficiency. And it didn't hurt that both airlines were launching the DC-10 which was powered by the same GE CF6 engine that Beteille wanted as an option on the A300. 

I had posted earlier about American Airlines' selection of the DC-10 and how American had laid out the original specifications for a widebody twin. The other airlines briefed wanted either three engines or four engines and American was the only airline who wanted only two engines. After meeting with United Airlines in San Francisco, Beteille met with Frank Kolk, American Airlines' VP for Development Engineering who originally authored the specifications that led to the DC-10. When Beteille met with Kolk, the tough-talking Texan admitted that he was disappointed that the DC-10 would have three engines as he would have much preferred a widebody twinjet. Neither McDonnell Douglas or Lockheed was interested in a twinjet and Kolk was very enthusiastic to meet with a team that shared his vision for widebody twin despite American's launch of the DC-10. In their discussions, Kolk discussed in detail what American wanted and its reasons for wanting a twinjet (fuel economy, operating economics, lower price per aircraft given that engines can amount to 35-40% of the cost of a new jet). Knowing what Beteille had planned, Kolk shared the original specifications with him and Beteille quickly returned to Europe and used American's specification and results of his discussion with Frank Kolk to nail down the final configuration and operating parameters of the A300. 

On 11 December 1968, the newly-formed Airbus Industrie revealed its Airbus A300B design to the aviation world. To this day Roger Beteille believes that it was the advice and discussions with Frank Kolk that made the A300 so successful that it formed the basis of the later A310, A330 and A340 jetliners. Ironically, it wasn't until April 1988 that American Airlines took delivery as the launch customer of the extended range A300-600R that was recently retired after over 20 years of service with American. Despite already having the Boeing 767-200/300 in the fleet, the A300 in its penultimate incarnation did eventually serve with Frank Kolk's airline!

07 September 2010

The Canceled British Aircraft that Cost the UK Industry

I bet you thought you were going to be reading about the BAC TSR.2 when you came across the title of today's post, but while there's no arguing the effects that the TSR.2 cancellation had on the British aerospace industry, there was a canceled aircraft that came before the TSR.2 that some have argued cost British industry far more than could ever have been imagined. In 1951 the government had issued a specification for a new long range strategic transport that would be able to move 120 troops long distances to replace the elderly piston-powered Handley Page Hastings. It was envisioned that this new transport could also move personnel and equipment rapidly around the world and deploy as necessary with the new V-force bombers that were soon to enter service with the Royal Air Force. The main condition of the specification was that it had be based on existing design. 

Five companies submitted proposals, with Bristol submitting a version of the Britannia turboprop transport, Saunders Roe submitting a variant of their Duchess flying boat, and Handley Page, Avro, Vickers, and Short submitting transports based on their bomber designs (Victor, Vulcan, Valiant, and Sperrin, respectively) and powered by the new Rolls-Royce Conway turbofan. De Havilland submitted a stretched version of its Comet 1 jetliner. Bristol's Britannia variant was eliminated early due to it being too slow, along with Saunders Roe's flying boat. The Sperrin was next eliminated as the transport version had a fuselage only 9 feet wide with accommodation for only 50 passengers or personnel. Handley Page and Avro's submissions were judged too risky for the RAF contract, leaving only Vickers and De Havilland as the remaining designs not eliminated.

It was realized early on after Vickers was named the winner of the RAF competition that what the RAF needed was not terribly dissimilar with BOAC's need for a long range jetliner that offered more capacity and range than the De Havilland Comet 1. The original specifications that Vickers won was then amended with the requirement that the jet transport also earn a certificate of airworthiness from the civil aviation authorities. With the new amended specifications in place, an order was placed with Vickers for the V1000 prototype aircraft, serial number XD662, in March 1953. 

The V1000 would be the RAF transport version and the anticipated civilian version was the VC7. With construction of the V1000 prototype underway in the summer of 1954, the RAF ordered six aircraft with an eventual requirement of twelve aircraft. BOAC was regularly consulted through this phase as they wanted to put the VC7 on the North Atlantic routes to Canada and the United States as well as on the longer Empire routes that couldn't be served by the Comet 1 jetliner. Besides BOAC, Trans Canada Airlines (Air Canada's predecessor) and Pan American showed significant interest in the VC7. Even BEA expressed an interest in the VC7 for its longer European services.

To meet BOAC's wishes, the V1000/VC7 was a bit larger than the RAF desired, mainly out of a need for the wing fuel capacity to meet BOAC's range requirements. Four Rolls-Royce Conway engines were mounted in the wing root similarly to the Vickers Valiant only the wing was larger and more swept with Kuchemann wingtips (similar to the 707-320BAdv and 707-320C's wingtips) and low mounted. The fuselage had six-abreast seating with a 12.5 foot diameter. This was significant at the time, as Boeing was wrestling with the cabin diameter on its anticipated Boeing 707 and Douglas at the time was still contemplating five-abreast seating for its coming DC-8. Unfortunately prototype construction at Vickers' Wisley facility showed that the V1000 prototype's weight would be about 18,000 lbs higher than planned.

It would have been a simple matter to have upgraded the Conway turbofans, but for whatever reason, BOAC's enthusiasm for the VC7 cooled as the planned weight with the intended engine would rule out London-New York nonstop services. Ironically, several years later when BOAC ordered the 707-430, it would have Conway turbofan engines that were upgraded that would have worked on the VC7! Government meetings in September 1955 formalized BOAC's disinterest in the VC7 and suggestions were made that De Havilland put forth a stretched version of the Comet as well as refinements to the Bristol Britannia as being suitable for BOAC's needs. In addition, BOAC looked further ahead to the mid-1960s for a possible supersonic transport. Despite BOAC's incomprehensible stance, Vickers anticipated the V1000 prototype's first flight in June 1956 with the first production aircraft flying in 1959 with inaugural airline services in late 1959/early 1960 (not too far off from when the Boeing 707 began its passenger services). In a bid to maintain the competitiveness of the VC7, Vickers explored other engine options and even looked at a version of the VC7 with each of the Conway turbofans in its own podded nacelle under the wing, not unlike that of the 707 and DC-8's layout.

By this point the RAF was entering a period of fiscal austerity and it's most expensive item to date was the V1000/VC7 project. Without mentioning the V1000/VC7, the British government cautioned the RAF to scale back its expenditures. Politics came into the picture with the prospect of the end of Comet production which would have affected one of the Comet's main subcontractors, Shorts in Belfast. A desire to keep Shorts busy shifted the support amongst some MPs in Parliament against the Vickers jetliner. In addition, the Britannia was having teething problems with its turboprop engines and was selling slow. Some ministers in the government felt that support should be given to the Britannia program instead of embarking on the all-new Vickers jetliner. 

Some historical accounts point the finger at BOAC for planning to procure US jets from the start and with the support of some in the government, did what it could to commit formally to the VC7. A spirited debate in Parliament dragged on for weeks with the supporters of the Vickers projects openly declaring that the VC7's cancellation would "give the large jet market to the Americans for the next 20 years". Rather obtusely, several government officials proclaimed that the planned performance of the Boeing 707 and DC-8 would make them cost-prohibitive for many of the world's airlines and the speed advantage over the Comet and Britannia would not matter to most passengers! With the V1000 prototype 75% complete, the project was ordered shut down by the British government on 11 November 1955, and this was despite intensive lobbying by Trans Canada Airlines. 

For many observers, it was the cancellation of the Vickers VC7 and not the TSR.2 where the British aerospace industry lost its way. Sir George Edwards, managing director of Vickers and the chief designer of the V1000/VC7, had lamented that BOAC and the government had simply handed over the lead in jetliner technology to the Americans for "generations to come."

Source: Stuck on the Drawing Board: Unbuilt British Commercial Aircraft Since 1945 by Richard Payne. Tempus Publishing, 2004, p38-42

04 September 2010

Boron-based High Energy Jet Fuels

In 1910, German chemist Alfred Stock began to experiment with taking hydrocarbon-based compounds (all fossil-fuels are hydrocarbon-based) and using boron as a substitute for carbon. Given that boron's nearest neighbor on the periodic table of the elements is carbon, Stock was intrigued by the possibility of using boron-based compounds. While successful in making small quantities of boron-based compounds, the process needed was tremendously expensive and yielded little product which at the time had no practical applications. However, in the 1930s, boron's potential began to emerge when it was found that boron-based materials produced a very high heat than the corresponding carbon-based compounds, making boron-based fuel worth studying. Prior to the Second World War, pentaborane and other boron-based compounds were synthesized, but again, practical applications were still lacking despite the promise as a high-energy fuel. At the end of the war, the U.S. Army organized a pilot program to produce boron hydrides (the boron counterpart to hydrocarbon compounds) in more significant quantities as a possible rocket fuel. The boron hydrides created could produce up to 30,000 BTUs/lb, compared to 18,000 BTUs/lb for comparable hydrocarbon fuel. 

General Electric opened a boron hydride research facility in Malta, New York in the early 1950s to continue the work started by Alfred Stock forty years earlier and managed to several hundred pounds of boron hydride compounds for research use. A plant in Muskogee, Oklahoma, also operated under a government contract to synthesize more boron hydride compounds and managed to produce 300,000 lbs of boron fuel. By the early 1950s the possibilities of boron fuels got the attention of jet engine manufacturers. Various high-energy fuels (HEFs) were studied like liquid hydrogen, for example, but boron fuels offered the most promise as they weighed the same and occupied the same volume as conventional jet fuels. For a given quantity of boron fuel versus conventional jet fuels, as much as 40% more energy could be produced. Because boron HEFs had such similar properties to jet fuels, they could be handled and used similarly, unlike liquid hydrogen fuels. 

GE led the way in boron HEF research in jet engines, operating a modified J79 turbojet engine at NASA's Lewis Flight Propulsion Laboratory to run on boron HEF. Calculations showed that if boron HEF were used only in the afterburners along with regular JP-class fuels, a range increase of 16% was possible. If the same aircraft were to use boron HEF exclusively, an range increase of 30% was possible. From the viewpoint of the United States Air Force, aircraft using boron HEF would have longer range and be less reliant on air refueling. In addition, 95% of the world's boron oxide was located outside of Soviet-controlled areas, with the vast majority of those boron deposits in the desert regions of California and Utah. Despite the promise it held, by 1955 the USAF had still to set up any organized study of boron HEF. 

Despite official disinterest, the US Navy's Bureau of Aeronautics did fund boron HEF studies starting in 1952 under Project ZIP in which two chemical companies were contracted to produce boron HEFs. As a result of the Navy's funding, boron HEFs began to be known as "zip fuels". One of the contractors produced a 10-boron compound called decaborane which showed the most promise. The Navy's work got the USAF's attention and decaborane would be designated HEF-3 and all research efforts focused on the use of HEF-3 with the USAF taking over direction of GE's boron fuel work. By 1957, GE reported to the USAF that HEF-3 was a feasible, but that significant technical hurdles remained given the high toxic nature of HEF-3 and the fact that boron oxide deposits were left on engine components which accelerated wear and tear of the powerplants. 

About this time both Boeing and North American were working on the WS-110A (Weapons System 110A) project which would ultimately result in the North American XB-70 Valkyrie. The stringent specifications of WS-110A called for Mach 3 speed but intercontinental range for a new supersonic bomber to replace the Boeing B-52 Stratofortress. HEF-3 became an attractive fuel option for both companies even though the USAF and the Strategic Air Command never specifically directed the use of HEF-3 as a requirement. In December 1957, North American was selected by the USAF's B-70 Program Office as the winning contractor in the WS-110A competition. The Program Office suggested that use of HEF-3 on the XB-70 would be the most economical means of getting the required 6,500 mile range. While still not requiring HEF-3 for the design, funding was made available for the modification of the intended powerplant of the XB-70 Valkyrie, the GE J93 engine, to run on HEF-3. Design work on the XB-70 at North American proceeded on the assumption that the aircraft be able to operate on both conventional JP-class fuels and HEF-3. 

Requiring the use of HEF-3 on the XB-70, however, was withheld by the Pentagon pending further evaluation of the operational advantages and disadvantages of HEF-3. While the refining of JP-class fuels was relatively simple, the production of HEF-3 required several extra steps beginning with simpler boron compounds. These extra steps added considerable cost to the price per gallon of HEF-3. Estimated of an HEF-3 facility built and operated to support one combat wing of operational B-70As resulted in a $10/gallon of HEF-3; adjusting for inflation, a gallon of HEF-3 today would cost just over $75!

Compared to the JP-4 fuel that was to be used on the XB-70 prototypes, HEF-3 produced 25,000 BTUs/lb compared to 18,000 BTUs/lb for JP-4. The spontaneous ignition temperature for HEF-3 was 2,600 degrees Fahrenheit compared to 4,550 degrees F for JP-4. While HEF-3 presented on issues when in contact with metals, there were considerable concerns about it coming into contact with non-metal parts of the Valkyrie's fuel system. In addition, HEF-3 was more toxic than cyanide, which complicated storage and handling at SAC bases. The lower flashpoint of HEF-3 meant that nitrogen inerting of the fuel tanks was a required necessity and even the smallest leaks were unacceptable. In 1958, NASA, North American, the USAF and several chemical contractors formed an HEF Guidance Committee to provide more direction to research efforts and to keep those efforts in line with the development of the B-70. At this point, the intent at North American was to create a dual-fuel bomber that used JP-4 and HEF-3, but it began to add a significant cost to the unit cost of the Valkyrie, particularly when GE's own work on the HEF-3-powered J93 engine began to fall behind schedule. Despite this, in the summer of 1959 the Strategic Air Command began making its initial budget outlays for FY1960 for HEF-3 production to support the production Valkyrie bomber. 

Dissatisfied with the progress, though, just weeks later the Pentagon canceled the HEF-3-powered J93 engine program and limited the Valkyrie program to the use of JP-4 fuel only. Testimony by USAF scientists before Congressional committees revealed that the technical hurdles and the operating cost of using HEF-3 as a jet fuel were prohibitive given the defense budget of the day. With the winding down of the HEF-3 program, the only research that remained on boron fuels lasted in the early 1960s at Edwards AFB as an additive to rocket propellant. There was, however, small consolation to the engineers and scientists involved that Soviet research efforts proved to be equally frustrating in making boron-based fuels practical. The hazardous nature of boron fuels for the most part proved to the final nail in the coffin of the research work. 

Source: Valkyrie: North American's Mach 3 Superbomber by Dennis R. Jenkins and Tony R. Landis. Specialty Press, 2008, p77-82.

02 September 2010

The Martin XB-48

In November 1944 the US Army Air Forces looked ahead to the future of jet technology in issuing a specification for a jet-powered bomber with a range of 3,000 miles, a service ceiling of 45,000 feet and a maximum speed of 550 mph. By January of the following year the requirements were increased with the necessary ability to carry specific types of large bombs in the USAAF inventory. Four companies would eventually come to submit designs that would reach the flying hardware stage- the North American XB-45 Tornado, the Convair XB-46, the Boeing XB-47 Stratojet, and the Martin XB-48. With the XB-45 and XB-46 being four-engined bombers, they were paired up to compete with each other for a production contract and the XB-47 and XB-48 both being six-engined bombers, ended up being paired up to compete as well. By December of 1945, the Glenn L. Martin Company in Baltimore signed a contract with the USAAF for its submission, the Model 223 which received the designation XB-48. A newer contract superseded the original contract which called for two XB-48 prototypes with a first flight date no later than the end of September 1947. 

While the general layout of the Martin XB-48 was conventional (straight wings, for instance), there were many features on the XB-48 that were unique and ground-breaking for aircraft technology of the day. Since the wings were too slender to carry the main undercarriage, the XB-48 featured a bicycle undercarriage with outrigger wheels that retracted into the outer sections of the underwing jet nacelles. This landing gear arrangement was first tested on a modified Martin B-26 Marauder nicknamed the "Middle River Stump Jumper" and designated XB-26H. The other significant unique feature of the XB-48 was that in order to keep the wingspan reasonable, the three engine nacelles on each wing were grouped together to form a lifting surface in which the nacelles top surface was faired into the wing and contributed to the overall wing lift. The General Electric J35 engines had their own sub-nacelles with an air duct passing between each nacelle and exhausting out the back of the nacelle. The jetpipes were also adjustable via flaps that deflected the jet exhaust. 

The first XB-48 made its first flight at the Middle River plant's airfield on 22 June 1947 and flew to NAS Patuxent River 80 miles away for more flight testing. The J35 engines proved to be one of the biggest headaches in the flight test program. The first XB-48 aircraft went through fourteen J35s in only 44 test flights! By this time the USAAF was an independent military branch as the United States Air Force and flight testing of both the XB-48 and the Boeing XB-47 showed that the Stratojet was clearly the superior aircraft thanks to its more powerful J47 engines and highly refined aerodynamics with its thin swept wing. Martin's XB-48 ended up being 50mph slower than its original design speed and as a result, the XB-48 program was canceled by the USAF in September 1948 with an order of the first production B-47A Stratojets. 

However, the USAF did make enough funds available for the completion of the second XB-48 prototype and for its flight testing. The second XB-48 first flew on 16 October 1948, three months behind schedule. But the delay was of little significance since the USAF had already terminated the program. Martin then offered to modify the XB-48 design in 1949 with XT40 turboprops which would have been more capable than the B-50 Superfortress, but by this point the USAF was interested only in pure jet bombers, not to mention that the XT40 was a Navy-funded engine and in those days, intraservice rivalries played a significant role in weapons development. In March of that year, Martin was formally notified of the USAF's lack of interest in the XT40-powered version of the XB-48. 

With the formal end of the flight test program in the summer of 1949, Martin elected to keep flying the XB-48 as test beds. The first aircraft would be used as a spares source to keep the second aircraft flying and test schedules were drawn up to test items like autopilot systems, engine cooling technologies and hydraulic equipment. In the end, though, even those tests got canceled and the second XB-48 ended up only flight testing a thermal de-icing system. In September 1951 the sole remaining XB-48 was flown to the Aberdeen Proving Ground in Maryland and static tested to destruction.