The Ryan FR-1 Fireball and F2R Dark Shark: An Evolutionary Dead-End

When the US Navy initiated the development of its first jet fighter, the McDonnell FD-1/FH-1 Phantom, in 1942, not only did it hedge its bets on McDonnell's design by carrier testing the Lockheed P-80 Shooting Star, but it also initiated a back up program at the insistence of the Navy's Bureau of Aeronautics (BuAer) for a mixed-powerplant fighter that combined a conventional piston radial engine with a jet engine. There were still a lot of unknowns about the operation of jet aircraft from fleet carriers and the concept of a mixed powerplant fighter would combine what was known- that a conventional radial engine had the performance for a carrier takeoff and a wave-off from landing and that a jet engine could provide a boost for high speed performance. At the same time as the start of the FD-1/FH-1 program, BuAer held a competition for a mixed-powerplant fighter which was won by San Diego-based Ryan Aeronautical Corporation which started work in 1943 on the prototype for the FR-1 Fireball.

Ryan FR-1 Fireball
(Wikipedia)

The Fireball's radial engine was a Wright R-1820 Cyclone 9-cylinder radial engine generating 1,425 horsepower. The R-1820 was used on a variety of World War 2 aircraft from the Boeing B-17 Flying Fortress to the Douglas SBD Dauntless and Curtiss SB2C Helldiver. This was a surprising choice given that the standard engine of the Navy fighters of the day was the 2,000 horsepower Pratt & Whitney R-2800 18-cylinder Double Wasp. The jet engine in the rear fuselage, fed by wing root intakes, was a General Electric I-16 (later redesignated J31) developing approximately 1,600 lbs of thrust. The I-16/J31 was a GE production version of the Whittle W.1 centrifugal flow turbojet and was the first production jet engine built in the United States. Outside of the Fireball, two of the same jet engine were used on the Bell P-59 Airacomet. Development of the three prototype XFR-1 airframes proceeded along remarkably smoothly and the prototype made its first flight on 25 June 1944 powered only by its piston engine. On the third flight, the I-16 engine was fitted to the prototype and used successfully.

The Fireball boasted excellent cockpit visibility but one of its other unique features was it was the first production carrier-borne aircraft to have a tricycle landing gear. This was done primarily out of necessity to elevate the jet engine exhaust up and away from the wooden decks of the Navy's fleet carriers. Despite the loss of the three prototypes, the Navy was anxious to field the FR-1 Fireball and had already ordered 100 aircraft a year before the first flight of the prototype. With satisfactory flight testing and excellent performance, another 600 aircraft were added to the order in 1944. The Navy wanted the Fireballs in the Pacific as a Kamikaze interceptor- Fireballs were planned to be used in combat air patrols, loitering on their radial engines. When inbound Kamikazes were detected on radar, the Fireballs would light up the jet engine and speed off to intercept the enemy. At the end of 1944, the Navy ordered 600 of a faster variant, the FR-2, that had a more powerful R-1820 engine that developed 1,500 horsepower. 

VF-66 Fireballs in formation flight
(San Diego Air & Space Museum Archives)

Navy fighter squadron VF-66 stood up at NAS North Island where the Ryan plant was located to speed the introduction into service of the Fireball. Instead of the usual operational evaluations and demonstrations, VF-66 was tasked to get the Fireball into action as soon as possible. Unusual for a Navy squadron of the day, VF-66 was made up of senior officers and experienced pilots. Five days after VF-66 stood up on New Year's Day 1945, the first FR-1s were making their initial carrier qualifications aboard the USS Ranger in preparation for combat deployment. The squadron pilots enjoyed flying the FR-1 for its speed and maneuverability. Pilots often would make low passes at area airfields with the front prop feathered to confuse tower and airport personnel. By July 1945 VF-66 was in final preparations to take the FR-1 into combat but it was all for naught when the Pacific War ended the following month with surrender of Japan after the atomic bombings of Hiroshima and Nagasaki. The Fireball was officially unveiled to the public in September 1945 but only 66 FR-1s were produced and delivered before the war ended, the balance of orders for the FR-1 and FR-2 being canceled. After the war in November 1945 a Fireball that suffered a radial engine failure landed on the USS Wake Island to be come the first jet landing on an aircraft carrier, but obviously not intentionally!

Looking to improve the Fireball's performance, Ryan proposed the FR-3 that would have taken the faster FR-2 design and swapped out the I-16 engine for a more powerful GE I-20 engine that offered 2,000 lbs of thrust. The FR-3 never got built, but Ryan did a contract for a prototype of the FR-4, which used a 3,400-lb thrust Westinghouse J34 engine in the rear fuselage. The XFR-4 did fly, and the main external difference was the relocation of the jet intakes from the wing roots to the lower sides of the nose just aft of the radial engine. Doors could close off the NACA-style flush intakes to keep the jet engine from windmilling and producing drag and small eyelid doors could increase the area of the intake as well. The XFR-4 added 100 mph to the top speed of the Fireball, but only one prototype was built. The small number of FR-1s, however, were withdrawn from service when in 1947 they were found to have significant structural fatigue in the aft fuselage just behind the wings. The last flyable FR-1 arrived at the Naval Air Technical Training Center in Memphis, Tennessee, to be used as a maintenance trainer.

Ryan F2R Dark Shark configuration
(San Diego Air & Space Museum Archives)

It wasn't the end of the road for the Fireball just yet, though. The Powerplant Division of BuAer still remained skeptical of the performance of jets in the carrier landing pattern. Ryan was asked to further develop the FR-1design by replacing the radial engine with a General Electric 1,700-horsepower XT31 turboprop engine. The XT31 was the first turboprop engine designed and built in the United States and was also used on the Air Force's Convair XP-81 turboprop/jet fighter. The new Ryan fighter was designated the F2R Dark Shark and though it retained the wing root intakes and the I-16/J31 engine of the FR-1, it had an impressive climb rate but lacking the drag-reducing jet intakes of the FR-4, it was actually slower than the XFR-4 in level flight. With the large 8-foot prop, the Dark Shark demonstrated improved performance in the carrier landing pattern over the FR-1, but by the time of its first flight in November 1946 McDonnell had proven the practicality of pure-jet carrier operations with the FD-1/FH-1 Phantom and the last resistance within BuAer to pure jets had ended as the Navy decreed that all future fighters after the Grumman F8F Bearcat would be pure jets.

The Dark Shark in flight
(San Diego Air & Space Museum Archives)

The Air Force (then still the USAAF) was impressed with the performance of the XF2R-1 Dark Shark prototype and asked Ryan to make some modifications to evaluate it in competition against the Convair XP-81. What was designated the XF2R-2 featured the NACA flush intakes on the nose of the XFR-4 feeding a Westinghouse J34 engine. The XF2R-2 was ultimately never built other than as a mockup, as the Air Force decided, like the Navy, that mixed powerplant fighters were an evolutionary dead end and the future lay with pure jets.

I should also mention the Curtiss XF15C which was also planned as a Navy mixed-propulsion fighter. But that aircraft will be getting its own article at a later date here at Tails Through Time!

Further reading: 

The Coming Kamikaze Threat in World War II We Never Faced
Refining Anti-Submarine Warfare: The Grumman AF Guardian
The Ground-Breaking Gun Turret of the Grumman TBF Avenger
The Boeing PBB Sea Ranger: The Best Flying Boat at the Worst Possible Time

Source: U.S. Naval Air Superiority- Developement of Shipborne Jet Fighters 1943-1962 by Tommy H. Thompson. Specialty Press, 2008, p28-30.

Birth of the Lion: The Development of the IAI Kfir

Mirage IIICJ Shahak (Sky Blazer)

In the early 1950s, the most advanced jet aircraft in the IDF/AF was the Gloster Meteor, the first examples being delivered from Great Britain in 1953 which marked the IDF/AF's first combat jet equipment. Although the Meteors gave good service to the Israelis, the supply of more advanced MiG fighters to its Arab neighbors meant that Israel needed to something more capable than the Meteor- their first choice was the North American F-86 Sabre, but its purchase was thwarted by American government. Israel then turned to France and formed a remarkably close relationship with Dassault in particular. The first Dassault Ouragan jet fighters were delivered in October 1955 as a stopgap measure until the arrival of the supersonic-capable Dassault Mystere IVA in April 1956, becoming the first Israeli combat aircraft capable of breaking the sound barrier. The improved Dassault Super Mystere became operational with the IDF/AF in December 1958 along with the Sud Aviation Vatour strike fighter. Israeli Aircraft Industries, started in 1952 as Bedek Aviation in Tel Aviv by American Al Schwimmer, had begun license production of the French jet trainer Fouga Magister in 1957 with the first wholly IAI-built example rolling out in 1960. The IDF/AF's relationship with Dassault as one of its best customers continued with the arrival of the Mirage III series. Israel had a custom variant based on the Mirage IIIC interceptor designated the IIICJ which was first delivered to the IDF/AF on 7 April 1962. IAI's skill set expanded as it modified the Mirage IIICJs as needed for Israeli needs, one of which was a removable nose that contained cameras for reconnaissance missions. It would be an Israeli Mirage IIICJ that scored the first aerial victory for the entire Mirage series worldwide against a Syrian MiG-21 on 14 July 1966. Known as the Shahak (Sky Blazer) in IDF/AF service, the Mirage IIICJs were an integral part of the IDF/AF until their retirement in 1982.

When Charles de Gaulle was elected president of France in December 1958, there was nothing to indicate that the long standing relationship between France and Israel would change for the worse. On 7 April 1966, Israel signed an agreement with Dassault for a custom variant of the Mirage 5 optimized for ground attack and designated Mirage 5J. Named Ra'am (Thunder), the Mirage 5J was a quantum leap in capability over the Mirage IIICJ. Since the weather was generally good in the Middle East, the Mirage 5J (as well as the rest of the Mirage 5 series) traded the all-weather radar capability for an increase in fuel and weapons load (32% more fuel in fact) and small radar ranging unit in a slimmed down nose. Dispensing with many of the electronics of the Mirage IIICJ, the Mirage 5J was not only more capable, but cheaper, with the initial contract for 50 Mirage 5Js and two dual-seat trainer versions of the 5J. Many IDF/AF pilots like the legendary Danny Shapira completed the Mirage 5J flight test program after its first flight on 19 May 1967. But the winds of change were coming to the Middle East despite the rapid progress on the Mirage 5J program by Dassault. With France losing Algeria in 1962 and de Gaulle's desire to be a player in Middle East politics beyond the United States and the Soviet Union, relations between France and Israel were cooling and came to a head in June 1967 during the Six-Day War. The Mirage 5J's first flight was less than a month prior when de Gaulle announced an arms embargo on Israel just three days prior to the start of the Six-Day War. At first the embargo was partial and hope held out that the IDF/AF would still get the Mirage 5J aircraft. But de Gaulle insisted on Israel withdrawing to its pre-1967 lines as a prerequisite for lifting the embargo, something the Israelis obviously refused to do. When the PLO launched a terrorist attack against El Al at the Athens airport on 26 December 1968, the Israelis responded with reprisal attacks against the PLO stronghold in Beirut two days later. In response, France imposed a total embargo on Israel. 

Armee de l'Air Mirage 5F (an embargoed Mirage 5J in French service)

Despite the embargo, Dassault completed the Mirage 5J production run on 19 June 1969, but the completed fighters were put into storage. The Mirage 5J would become the basis for a new family of Mirage 5 variants that would prove popular with other air forces. The Israeli Mirage 5Js in storage were put into service with the French Air Force (AdA) as the Mirage 5F. Some of these airframes ultimately ended up with Chile years later. Israel would eventually get a refund of its money for the first variant of the Mirage 5 series, but in 1969 with tensions running high in the wake of the 1967 war, the only option was for Israel to build its own fighter aircraft. Despite the initial partial embargo, Israeli Aircraft Industries had negotiated for license production of the Mirage 5J in Israel and at the end of 1967 an agreement was signed between IAI and Dassault. Dassault felt that since they were a private company, they weren't bound by the embargo, but the maker of the Atar 9C turbojet of the Mirage 5J, SNECMA, was government owned. Time was of the essence and it would have been time consuming to find a replacement engine for the Atar 9C. At the time, the Swiss company Sulzer was license building the Atar 9C for Switzerland's Mirage order and an engineer with Sulzer, Alfred Fraunknecht, was approached by the Mossad with a deal- supply the engineering data and blueprints for the 9C for $250,000. Approximately 200,000 drawings were transferred before Swiss authorities arrested Fraunknecht and sentenced him to four and a half years of prison. 

Neshers on the flightline. Note the nose painted black to appear like a IIICJ.

Keeping the name Ra'am (Thunder) that was intended for the Dassault-built Mirage 5Js, a highly classified program got underway at IAI to essentially build the 5J with a reverse-engineered Atar 9C. Despite the embargo, the Israelis found many sympathetic supporters in the French aerospace industry to assist with the production of what was called the Nesher (Vulture). Dassault supplied manufacturing jigs and tooling and even whole airframe subassemblies despite the total embargo. Oddly enough, spare parts for the Mirage IIICJ fleet were exempt from the embargo and with the Nesher being a derivative of the 5J which was a derivative of the IIICJ, many spare parts ended up on Nesher aircraft. The first Nesher aircraft made its maiden flight on 21 March 1971 and became operational with the IDF/AF the following October. When the Nesher program ended in 1974, 50 Nesher A single seat fighters were built as well as 10 Nesher B combat trainers. 

IAI Kfirs (from the DML/Dragon 1/144 scale kit box art)

While the Nesher was becoming operational, IAI then turned its attention to rectifying the deficiencies of the aircraft, the biggest of which was the Atar 9C engine. Focus then turned on a re-engined Nesher as the next follow on aircraft. The General Electric J79 was selected as it already powered the F-4E Phantoms that had already been in IDF/AF service for several years. On 21 September 1970 (before the Nesher's maiden flight), IAI conducted the maiden flight of a demonstrator to prove the J79 could be integrated into the Mirage airframe. This demonstrator was a two seat Mirage IIIBJ called the Technolog. The flight test program of the Technolog was used to uncover any issues with using the J79 on the Mirage airframe. The new production aircraft that would use the J79 in a Nesher airframe was named Kfir (Young Lion) and the prototype Kfir that first flew on 4 June 1973 was in fact a Nesher modified to accept the J79 and be representative of the production standard Kfir. The deliveries of the first Kfirs was interrupted by the October Yom Kippur War that year, but it was apparent that the Kfir wasn't the leap in improvement over the Nesher that IAI had hoped. The fix was aerodynamic and would applied to subsequent Kfirs- first, a saw tooth was added to the outboard wing which increased wing chord and the saw tooth created a vortex that energized the wing air flow and acted as a wing fence to stop drag-inducing spanwise flow. Next, canards were added above and behind the intakes which helped control the air flow over the wing and made destabilized the Kfir to make it more agile. Lastly, a pair of strakes was added to the extreme tip of the nose which helped smooth the airflow over the wings and canards. This configuration became known as the Kfir C2 and was the definitive production model that also had extra hardpoints for more weapons. The first production Kfir was delivered on 14 April 1975. One of the Israeli guests of honor was Alfred Fraunknecht, the Swiss engineer who had passed on the Atar 9C turbojet engineering information years earlier for the Nesher program.

Source: Aviation Classics: Dassault Mirage III/5, Issue 17. "Vultures and Young Lions" by David G. Powers, pp 70-81. Photos: Wings Palette, Wikipedia, DML/Dragon Models

The Lockheed C-5M Super Galaxy

The first production group of Lockheed C-5 Galaxy transports, designated the C-5A, were built in the 1970s and even then, there were issues with the jet's reliability. When the production line was reopened during the Reagan-era defense buildup in the 1980s, the C-5B was produced to introduce a variety of systems improvements aimed at boosting the jet's reliability. But the mission capable rate of the Galaxy continued to decline. In the mid-1990s, of the 126 C-5A/Bs in service at the time, up to 32 percent of them were down for maintenance at any one time. Of all the aircraft operated by the Air Mobility Command of the US Air Force, the C-5's mission capable rate was the worst, even worse than the 1950s-1960s vintage KC-135 Stratotankers! In 1998 the USAF initiated the AMP (Avionics Modernization Program) which improved many of the cockpit and traffic management systems of the aircraft. Despite this, the mission capable rates continued to deteriorate. By 2001, only 60% of the Galaxy fleet was operational at any one time. The airlift buildup for Operation Enduring Freedom in Afghanistan initially turned things around as increased funding for C-5 maintenance to operate the logistics air bridge to Afghanistan raised the mission capable rate to 75%. But the pace of airlift missions eventually took their tool on the Galaxy- there are reports of one operating location that was allotted ramp space for eight C-5s to be present and the unspecified base had twenty-two C-5 aircraft present, down for maintenance issues! The 2009 troop surge into Afghanistan further strained Galaxy operations with aircraft down for maintenance a fixture on the ramps at Ramstein AB in Germany and NAS Rota in Spain. Personnel joked that AMC stood for "Airplane Might Come".

Two overlapping upgrade programs took place to improve the C-5's abysmal reliability. The first one was the aforementioned AMP (Avionics Modernization Program) that started in 1998 with the last Galaxy coming out of the program in August 2009, with 55 C-5s (50 C-5Bs, 2 C-5Cs, and 3 C-5As) having went through AMP. The second program was the bigger one and addressed the weak link the Galaxy today- it's elderly TF39 engines. The Galaxy's TF39 turbofan engines are the world's first production high-bypass turbofan engine. GE began development of the TF39 in 1965 and on today's unmodernized C-5 Galaxy, represents 40+ year old technology that has long been surpassed by modern commercial turbofan engines. To address this capability gap, Lockheed and the USAF began the RERP program (Reliability Enhancement and Re-engining Program) which began in 2006.

With the announcement that the USAF was to end procurement of the C-17A Globemaster III after 223 aircraft, the modernization of the Galaxy took on added importance. RERP is costly- it's estimated that what is spent on each C-5 going through RERP is equal to buying two C-17A Globemaster IIIs. When each C-5 is delivered to Lockheed's facility in Marietta, Georgia, the first task is to remove the elderly TF39 engines and any last remaining amount of fuel from the aircraft, after which it is moved into a special modification bay for 18 months where nearly 11,000 feet of wiring is pulled out of the aircraft and replaced with modern systems. The most challenging part and part of what makes RERP so costly is the re-engining with the modern GE CF6-80C2 engines. Because of the 30+ years of wear and tear on each Galaxy, a special laser system is used to determine the optimum location for the pylon fittings- in effect, each C-5 going through RERP gets custom-made engine pylons.

Ironically the GE CF6-80C2 engine that replaces the TF39s was derived from the TF39. Designed originally for the Douglas DC-10 and the Airbus A300, the current version of the CF6 is the CF6-80C2 which entered commercial service in 1985. The -80C2 engine powers the two latest versions of the A300 (the -600 version), the two versions of the A310, four versions of the 767 family, three versions of the Boeing 747-400, and the McDonnell Douglas MD-11. Although the basic engine architecture is the same, the CF6-80C2 is much more efficient and modern engine than it was over thirty years ago when it first came to market. What this does to the Galaxy is nothing short of impressive. The addition of modern engines gives the C-5M Super Galaxy 22% more thrust, a one-third shorter takeoff roll, twice the climb rate, and for a given payload, just over 1000 miles more range. And this is before getting into areas like meeting strict noise standards at many of the world's airports when the C-5M has to fly into and out of those locations.

The first Super Galaxy, tail number 86-0013, a C-5B, was rolled out on 16 May 2006 and made its maiden flight on its new engines the following month on 19 June 2006. Following a successful flight test program, the first two examples were delivered to the 436th Airlift Wing at Dover AFB, Delaware. This past summer two C-5Ms joined eight C-5A/Bs on a marathon airlift effort to delivery Army helicopters from NAS Rota (where they had been delivered by ship) to Afghanistan. The eight older Galaxy transports accounted for 23 missions altogether, while the C-5Ms by themselves accounted for 22 missions! Despite having flown one less mission, the two C-5Ms accounted for 55% of the cargo delivered during that operation and boasted a mission capable rate of 96%, something that the Galaxy has never attained in its operational history previously.


Source: Combat Aircraft Monthly, November 2010, Volume 11, Number 11. "New Life in the Galaxy: Deep surgery renders cheaper, more powerful C-5M" by David Axe, p30-35.

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.

Irving Langmuir and Project Cirrus

By the end of World War II, Irving Langmuir was already a well-known industrial chemist with impeccable credentials that went as far back as before the First World War when he worked with GE and Thomas Edison to improve the incandescent light bulb, the basis of which led to his 1932 Nobel Prize in chemistry, becoming the first industrial chemist to win the prestigious award. But he had other pursuits and mind, having become interested in weather phenomena before the start of the Second World War. Not only was Langmuir interested in the weather, he saw a chance to even control the weather. At the time, the idea of weather modification and control had been established in the realm of pseudoscience practiced by half-crazed individuals. But in Langmuir, suddenly the field of weather modification had the clout of a prominent scientist. He successfully persuaded his employer, General Electric, to team up with the US Army Signal Corps and the Office of Naval Research in 1946 to start Project Cirrus.

Lanmuir teamed up with a GE machinist, Vincent Shaefer and a chemist, Bernard Vonnegut (author Kurt Vonnegut's older brother) to start some basic work in a research lab to determine the best way to cause precipitation to fall out of a cloud. Dry ice was found at first to be useful, but work also proceeded on silver iodide that was created by Vonnegut. In November 1946 the first aerial cloud seeding in history took place under Langmuir's direction near GE's headquarters in Schenectady, New York. Using a rented Fairchild 24 converted for crop dusting, a four mile long altostratus cloud at 4,000 feet was seeded with dry ice pellets fed into a funnel by Vincent Shaefer in the back of the aircraft. Within minutes, snow fell but evaporated at 2,000 feet. Undeterred, Langmuir tried a more ambitious experiment the following month using a bigger load of dry ice the following month. No precipitation resulted, but the following day upstate New York and Vermont were hit with the biggest snowstorm of the winter season that shut down business and caused accidents throughout the area. Though no connection could be made, many residents of upstate New York blamed Langmuir's experiments.

The US Weather Bureau (predecessor of the National Weather Service and part of the Department of Commerce) and its scientists, though, weren't convinced as no causal relationship could be drawn between that December seeding and the snowstorm the following day. Despite this, GE lawyers got spooked by the potential liability and insisted that Langmuir get the full cooperation of the US military as it was better shielded from the sorts of lawsuits GE feared. Military cooperation benefited Project Cirrus as more powerful aircraft with better load carrying capacities were no available. Boeing B-17s were first used which could seed as much as 80 pounds of dry ice pellets on each pass through target clouds. In October 1947 a USAF B-17 took off from MacDill AFB in Tampa to seed a weak hurricane that was stalled out off the coast of Jacksonville, Florida. Langmuir felt that seeding the rain bands of the storm with silver iodide would weaken it further. For whatever reason, the hurricane inexplicably strengthened, speed up, and struck Savannah, Georgia, causing several deaths and $34 million in damage. Once again, Project Cirrus was blamed for the strengthening of the storm even though the scientists of the US Weather Bureau insisted otherwise.

GE's legal department got spooked again and Project Cirrus was moved to New Mexico to try and create rain in the arid climate. For two years Langmuir's team seeded clouds with silver iodide crystals. Langmuir boldly announced to the press after two years that "only a few cents' worth of silver iodide could initiate dozens of rainstorms." He even appeared on the cover of Time magazine as a "rainmaker" and he quit his position at GE to speak throughout the country on the potential of rainmaking. Soon private pilots throughout the US started up "rainmaking" operations and cloud seeding took place over a six-state area, spurring Congressional hearings as local tourist attractions accused the seeding activities of affecting their businesses.

Even worse, the US Weather Bureau's scientists were busy debunking Langmuir's work. The New Mexico storms were usually the result of warm fronts that pumped Gulf moisture into the area. Study of hurricane records showed that the Savannah hurricane followed the same track as a storm in 1906, calling into question what if any effect had been caused by the seeding of that storm. Project Cirrus ended in a stalemate with the US Weather Bureau and in 1952 GE was more than happy to pull the plug on the project. Langmuir died in 1957 of a heart attack, but the work in the United States on weather modification hardly died with the death of its greatest champion.

Stay tuned for Part Two of this story!

Source: Air & Space Smithsonian, July 2010, Vol. 25, No. 2. "Climate Control: Irving Langmuir tried to change the world one storm at a time" by Sam Kean, p52-55.