The American V-1 Program 1944-1950

Beginning in 1942, Allied intelligence began a systematic analysis of the Fiesler Fi 103 flying bomb better known as the V-1. Analysis of crashed test articles combined with photoreconnaissance and intelligence collected by agents within occupied Europe led the United States in particular to restart its flying bomb programs in 1943 that had laid dormant for the most of the Second World War on account of what was felt to be beyond the current state of the art. In 1944, Northrop was contracted to begin development of the first US flying bomb, designated the JB-1. Running parallel to the Northrop effort was the reverse-engineering of the V-1 using 2,500 lbs of salvaged V-1 parts that had been provided by Great Britain. The parts arrived at Wright-Patterson Field in Dayton, Ohio, on 13 July 1944 and the US Army Air Forces directed the engineering staff there to build 13 copies of the V-1. Quite remarkably, the USAAF technical staff completed the first copy in just three weeks! To put the scope of the success of the Allied intelligence effort and the work the Wright-Patterson Field team into perspective, the first German V-1s struck Britain on 12-13 June 1944. By the end of the following month, the USAAF had its first copy of the V-1 and they had test fired the reverse-engineered pulse jet engine. A memo from the technical team responsible to General Henry Arnold, head of the USAAF, recommended mass production at the earliest opportunity- however, General Arnold and his advisors were well aware of the V-1's inaccuracy and despite reservations that production of an American V-1 would divert crucial wartime resources and manpower from battle-proven weapons, it was felt that if the guidance of the V-1 could be improved, an American version might be useful. 

The Republic-Ford JB-2 differed from the V-1 in minor details
(USAF/Wikipedia)

Republic Aviation was tasked with producing the American V-1 which was designated JB-2 with the first of the thirteen USAAF copies arriving on 8 September 1944 from Wright-Patterson Field. The USAAF ordered 1,000 JB-2s from Republic. The Ford Motor Company was tasked with producing the JB-2's pulse jet engine which was designated the PJ31. With Republic's resources nearly all committed to the production of the P-47 Thunderbolt, the company subcontracted the airframe assembly to Willys-Overland, the same company that built the Jeep. With Ford responsible for engine production, the Jack & Heintz Company of Cleveland which had been building aircraft electrical components and autopilots as a subcontractor was given responsibility for the JB-2's control system. Alloy Products of Wisconsin was given responsibility for the fuel tanks and pressure vessels used in the JB-2 while the Northrop was contracted for the JB-2's launch sled. The booster rockets that actually propelled the JB-2 off the ground were contracted to Monsanto. 

By the end of September 1944, the USAAF revised its initial order for 1,000 JB-2s to 1,000 JB-2s *per* month with a target goal to reach that rate by April 1945. The first JB-2 launch took place at Eglin Airfield in Florida on 12 October 1944- just three months had elapsed since start of the German V-1 campaign against London and the first American copy had made its first flight! Flight testing was also carried out at Wendover Field in Utah at the same time that the B-29 Superfortress unit that dropped the atomic bombs, the 509th Composite Group, was a tenant at Wendover training for their special mission. The flight tests didn't go too smoothy- by the first week of December, there were two successful flights out of ten launches. 

JB-2 air launch from a B-17 at Eglin Army Air Field in 1944
(USAF/Wikipedia)

Northrop's own flying bomb design, the JB-1, made its first launch in December 1944 but crashed after launch. (The JB-1 will be the subject of its own later article here at Tails Through Time.) With the the early failures of the JB-1 and problems with its jet powerplant, the USAAF decided to continue with the development of the Northrop design but production and operational priority went to the JB-2. Despite issues with accuracy in the flight tests at Eglin and Wendover, the USAAF leadership pushed for an increased production rate for the JB-2 to at least 3,000 per month. On 14 January 1945, General Arnold ordered another 75,000 JB-2s with the ability to launch 100 per day by September and 500 per day by January 1946 in anticipate of the invasion of Japan. On the next day, the JB-2 program got the same priority that was given to the B-29 Superfortress program. 

Despite the enthusiasm from the USAAF leadership, theater and operational commanders were skeptical of the JB-2. The generally poor European weather that was interfering with the strategic bombing campaign, however, offered perhaps some utility for the JB-2 as it wasn't dependent on clear weather- a view supported by Sir Trafford Leigh-Mallory, the head of the Royal Air Force and commander-in-chief of Allied air forces for the Normandy invasion as well as General Carl Spaatz, head of US Strategic Air Forces Europe. Spaatz, however, was a bit more measured in his support for the employment of the JB-2. He felt that it was more a harassment weapon that could be used when bad weather precluded a strategic bombing mission and outlined his planned use at 300 JB-2s per day only 10 days out of the month. But General Spaatz was very specific that operational employment of the JB-2 could not interfere with heavy bomber operations and he personally expressed concerns to General Arnold regarding the JB-2's cost-effectiveness given its inaccuracy. 

The JB-2 flight test program centered primarily on improving the weapon's accuracy. The first successful flights in the fall of 1944 showed an average error of eight miles at a range of just over 120 miles, not much better than what the Germans were averaging in their own V-1 campaign. The next step by the USAAF was to install radio guidance control in the JB-2. Using a radar beacon and remote control, it was thought the JB-2's accuracy could be improved. However, continued flight tests showed in 20 flight tests with the new guidance system, the JB-2's average error was no better than it was before with preset controls. Things did get better though- by war's end, the JB-2 with preset controls was averaging 5 miles error over a range of 150 miles and 1/4 mile error over a range of 100 miles with radio guidance. 

The biggest stumbling block to the operational deployment of the JB-2 in Europe in 1945, believe it or not, was logistical. The sheer numbers of JB-2s needed competed with other munitions production and it was estimated by some in the War Department that just transporting the JB-2 and its associated equipment to Europe would take up nearly 25% of Allied shipping capacity in the Atlantic. Brief consideration was given to moving JB-2 production to Europe, but there simply wasn't the production capacity anywhere else but the United States to produce the numbers of JB-2s planners envisioned using. 

With the end of the war in Europe, JB-2 production numbers remained in flux as planners debated what was needed for the planned invasion of Japan. By this point, however, the production and logistical concerns for the mass deployment of the JB-2 had exhausted the initial enthusiasm for the weapon. Production was halted initially at the end of January 1945 but then reinstated at a lower rate. By the time of the Japanese surrender, 1,385 JB-2s had been built when production was terminated.

Concurrent with the USAAF testing, the US Navy worked on a navalized version of the JB-2 that would have been launched from specially-modified LSTs and escort carriers during the invasion of Japan. Fifty-one JB-2s were requested by the Navy for its own testing program in September 1944 when production was launched. While airborne launches from B-17 Flying Fortresses were done during testing at Eglin Field, the Navy planned to launch JB-2s from Consolidated PB4Y Privateers as well. Navy planners, however, didn't expect operational capability with the JB-2 (which was called the Loon by the Navy) until August or September 1946. The first Navy Loon launch was on 7 January 1946 with the Secretary of the Navy approving the conversion of two submarines for Loon operations in March 1946. Conversion of the USS Cusk (SS-348) began in January 1947. The Cusk entered the history books on 18 February 1947 as the world's first missile submarine when it made its first Loon launch...which ended in failure after only 3.5 miles of flight. The Cusk finally had its first successful launch on 7 March 1947 after five tries. Submarine launch had become the Navy's focus for the Loon program with the USS Carbonero (SS-337) also modified for the program and by 1949 finally carried out a firing from a surface ship, the test ship USS Norton Sound. In March 1950, the Navy terminated in the Loon in favor of the more promising Regulus cruise missile. 

The USS Cusk fires a JB-2 Loon
(US Navy/Wikipedia)

With the US Air Force becoming independent in 1947, the JB-2 program was reactivated in March 1948 at Holloman AFB in New Mexico as part of a program for the development of missile guidance systems and seeker technology. Work using the JB-2 benefitted the later Matador cruise missile program with the JB-2 program winding down by 1949 with test airframes successfully being flown remotely and skid landed for recovery. A joint effort with Eglin AFB also used the JB-2 as a target drone for the development of gunsights. Interestingly "Flakzielgerät 76" was the German cover name for the V-1 during its development which loosely translates as anti-aircraft target device.

Further reading:

British Defenses Against the Summer 1944 V-1 Bombardment
Regulus: The US Navy's First Operational Nuclear Missile
CHECK SIX: Ships Damaged or Sunk by the Yokosuka MXY7 Ohka

Sources: The Evolution of the Cruise Missile: Comprehensive History from the V-1 and V-2 to the Tomahawk and Snark by Kenneth P. Werrell. Air University Press/USAF, 1983, pp 79-85. V-1 Flying Bomb 1942-1952: Hitler's Infamous Doodlebug (New Vanguard No. 106) by Steven J. Zaloga. Osprey Publishing, 2005, pp 39-41.

Project Thunderstorm: Storm Chasing with P-61 Black Widows

P-61 crew with their hail damaged aircraft
(NOAA History)

In the immediate postwar period the Civil Aeronautics Authority (CAA, the predecessor organization in the United States to the current FAA) began to gear up several research efforts in order to establish guidelines for the regulation of the anticipated boom in civilian flying. One of the areas that the CAA placed emphasis on was understanding the dynamics of severe thunderstorms which were all too common across many of the trunk routes of the United States. In 1945, the U.S. Congress authorized $250,000 to the U.S. Weather Bureau (which would become the National Weather Service in 1970) to study severe thunderstorms with specially-instrumented Northrop P-61 Black Widow fighters. Cooperating with the U.S. Weather Bureau were a number of organizations- the U.S. Army Air Forces, the Naval Research Laboratory of the U.S. Navy, the National Advisory Committee for Aeronautics (NACA, the predecessor organization of NASA), the Meteorology Department of the University of Chicago, the Physics Department of the University of New Mexico, the Electronics Department of the Massachusetts Institute of Technology, and the Soaring Society of America. With the U.S. Weather Bureau as the coordinating agency, University of Chicago meteorologist Dr. Horace Byers was appointed director of the Project Thunderstorm. 

The P-61's SCR-720 radar
(Wikipedia)

With the Second World War having ended just weeks prior to the Dr. Byers' appointment, there was a ready surplus of aircraft, pilots, and personnel to undertake the project. In addition, the CAA anticipated a rapid increase in postwar civilian flying. A spate of weather related accidents in the summer of 1945 also provided additional impetus to the endeavor. While other aircraft would be used in the study, the main storm penetration flights would use the P-61 Black Widows that once belonged to an Alaska-based USAAF weather reconnaissance unit. The aircraft were large with good range for multiple storm penetrations and were known to be tough. Pilots and crews were all volunteer and briefed in advance of the hazardous nature of the flights. The Black Widow in addition carried an onboard radar, the SCR-720. The radar was a joint development between Bell Laboratories and MIT as an improvement over previous airborne intercept radars which had a limited range of only five miles. Compared to previous AI units, the SCR-720 had a longer range (twenty miles in good conditions) and would be the primary AI night fighter radar of the Allies during the Second World War. One of the early problems of AI units in those days was attenuation and blocking of the radar beams by heavy precipitation- for Project Thunderstorm, though, this limitation was useful as it allowed the P-61's radar operator to get radar images of the thunderstorms at multiple levels. 

The pilots were selected from the Air Materiel Command's All-Weather Flying Division and were scrutinized closely for their skills and aptitude for the missions. The radar operators were all highly-trained and experienced individuals from the Navy and USAAF and the third member of the P-61 crew was a weather observer would would be responsible for collecting a variety of measurements during the storm penetration flights. 

The Soaring Society of America provided three Pratt-Read TG-32 two-seat gliders and pilots. The gliders were used to gather data on cumulus clouds before they had developed into thunderstorms as well as to make study flights on the storm periphery. Approximately 141 glider flights were made for the US Weather Bureau- one pilot, Paul Tuntland, got caught inside a thunderstorm updraft and was carried from 4,000 feet to 22,000 feet, setting a new national altitude record for gliders!

P-61s and a single F-15 Reporter getting ready to sortie
(NOAA History)

The first phase of Operation Thunderstorm took place over a sixty-square mile instrumented range near Orlando, Florida. Aircraft were based at Pinecastle Army Air Field, Florida (today's Orlando International Airport) using Black Widows fitted out with data recorders and weather instruments. Two seat glider aircraft were also used to gather data on the periphery of the storms as they entered the test range area. Microwave radar stations were set up around the Orlando area for early warning- as a storm was detected, the P-61s sortied and would penetrate the storm cell five aircraft at a time at 5,000-foot intervals from 5,000 feet to 25,000 feet. The same radar stations would also vector the P-61s into and around the the storms on their missions. Fifty ground based stations also were used to collect atmospheric data at ground level. Three radiosonde stations were also used to release multiple weather balloons into the storms in the test range. The test flights took place between 29 June and 18 September of 1946. The second phase took place at Clinton Army Air Field near Wilmington, Ohio (today's DHL Airborne Airpark), only this time there were 13 of the specially-instrumented Black Widows used plus four Northrop F-15s (the reconnaissance version of the Black Widow) owned by Northrop and single P-61 that was being used by Trans World Airlines for its own weather research. Starting on 1 May 1947, the aircraft would make storm cell penetrations every time a severe weather front passed through the area. 

SCR-720 radar image of a thunderstorm
(YouTube)

Pilots made their penetration flights with the trim set for straight and level flight. Once in the storm, they were to do their best to minimize control inputs as sensors would record not just the pilot's instrument panel, but also the power settings, control surface movements as well as the aircraft's motion as it was buffeted by the storm. Aircraft routinely landed after their missions with damage from hail and lightning strikes. Despite the punishment of the storms and the hazardous nature of the penetration flights, over the course of 1,362 missions, not a single aircraft or crew member was lost. In recognition of their skill and bravery, all the crews were awarded the Distinguished Flying Cross. 

By 1949, the study ended and the meteorology department of the University of Chicago was given responsibility for analyzing the data from both phases. One of the most prominent severe weather researchers came from the University of Chicago's department having had his start with the Operation Thunderstorm data- Theodore Fujita, who would later become one of the world's foremost experts on mesoscale systems and tornadoes- and who developed the Fujita Scale for tornadoes used today as the Enhanced Fujita (EF) Scale. 

Operation Thunderstorm contributed a large body of data that not only increased the safety of civil aviation, but also set the stage for improvements in severe weather forecasting. The use of the Black Widow's SCR-720 radar also led to the development of airborne weather avoidance radar by commercial aircraft. 

Further reading: 

Irving Langmuir and Project Cirrus

Project Stormfury 1962-1983

Weather Reconnaissance Squadron FOUR (VW-4): The Navy Atlantic Hurricane Hunters

The 1952 Carswell AFB Tornado

Sources: Wings of Fame, Volume 15. AIRtime Publishing, 1999, "Northrop P-16 Black Widow" by Warren E. Thompson, p91. "Thunderstorm Research Project" from In the Breeze Vol. 2, No. 12, January 10, 1946, pp1-2, accessed via NOAA History. "Project Thunderstorm" by Steve Zuger, Aviation History, July 2015, pp30-33.

27 Years Before the Eagle Was the First F-15

The Northrop P-61 Black Widow, despite having a wingspan of 66 feet and being the size of most medium bombers, possessed a high speed and maneuverability that made it a candidate for further development into a very-long range day fighter. With the war in the Pacific now on the front door step of the Home Islands, there arose a need for a fighter with a very long range to escort the Boeing B-29 Superfortress bombers from their bases in the Marianas and China to Japan and back. The development of the Lockheed XP-58 Chain Lightning was hobbled by troublesome powerplant issues and innumerable deficiencies uncovered in the flight test program for the Fisher XP-75 Eagle meant that the USAAF had to fall back on a long range version of the Thunderbolt, the Repubic P-47N. Not feeling that this was the optimum solution, the USAAF authorized development of twin-seat, twin-engine escort fighter designs to meet the need for a long-range B-29 escort. North American was issued a contract to develop the P-51 Mustang into the P-82 Twin Mustang while Northrop was given a contract to develop a day fighter version of the P-61 Black Widow. 

To save time given the pressing needs of the Pacific War, two P-16B Black Widow airframes were pulled from the production line (the aircraft were 42-39549 and 42-39557) to be modified into the XP-61E prototypes. The primary modification was the replacement of the center crew nacelle with a new nacelle that had only 50% of the cross-section of that of the Black Widow. Instead of housing three crew members, the new nacelle sat two pilots in tandem under what was a the time the world's largest single-piece bubble canopy. The air intercept radar in the nose of the Black Widow was replaced with four 50-caliber machine guns which would form the new fighter's main armament. The four 20mm cannon in the belly of the nacelle were retained on the XP-61E. Extra fuel tanks in the new crew nacelle aft of the cockpit gave the aircraft a 1,158-gallon fuel load, nearly double the 640-gallon capacity of the Black Widow. In addition, the XP-61E could carry four 310-gallon external fuel tanks as opposed to the just two external tanks of the Black Widow. 

By the time of the XP-61E's first flight on 20 November 1944 from Northrop's facility in Hawthorne, California, the war in the Pacific had progressed rapidly and the landings on Iwo Jima in February 1945 gave the USAAF an airfield that was halfway between its main B-29 bases in the Marianas and Japan. Basing of P-51 Mustangs on Iwo Jima now made the need for an escort fighter with the same range as the B-29 superfluous. However, with the planning underway for the Allied landings on the home island of Kyushu on October 1945 (Operation Olympic) and the landings on the main island of Honshu (Operation Coronet) set for the spring of 1946, a need arose for fast, agile reconnaissance aircraft to map the planned invasion zones and associated targets. While realizing that the reconnaissance need would ultimately be met by the Hughes XF-11 and the Republic XF-12 then under development, the USAAF wanted an interim design based on the XP-61E designated the F-15A Reporter. With an estimated eventual need for 320 F-15As, the USAAF ordered the first batch of 175 Reporters in June 1945 as Northrop's design would be ready much sooner than either Hughes or Republic's custom-tailored versions. 

Given that all that was needed was removal of the four 20mm cannon in the belly of the central crew nacelle and replacement of the 50-caliber machine guns in the nose with camera equipment, Northrop had the first XF-15 Reporter ready in only five weeks. The six camera stations in the nose could accommodate 17 different types of cameras in 24 combinations. With the armament removed, the F-15A would have a range of over 4,000 miles with 1,330 gallons (increased over that of the XP-61E thanks to the removal of the underbelly cannons) internally and another 1,240 gallons in the four external tanks. Despite such promising performance, the second XF-15A prototype was not completed until 10 August 1945 due to the need to fit turbosuperchargers to the Pratt & Whitney R-2800 radial engines, the day after the second atomic bomb was dropped on Nagasaki. 

With the Japanese unconditional surrender on 15 August 1945, the need for reconnaissance coverage for the invasion of Japan evaporated, but the USAAF recognized the need for detailed mapping of Japan and its occupied territories to support the postwar occupation and reconstruction of the country. As a result, the original purchase contract for 175 F-15A Reporters escaped the wholesale cancellations that swept the US aircraft industry following the end of the war. However, the contract was amended from 175 examples to just 36 aircraft on 21 May 1946. The first production F-15A Reporter was delivered to the USAAF on 4 September 1946. The planned penultimate reconnaissance aircraft of the war, the Hughes XF-11 and the Republic XF-12 Rainbow, made their first flights in 1946 on 7 July and 7 February, respectively. Tail number 45-59302 was the first operational F-15A accepted into service and was named "Klondike Kodak" and photomapping operations were started in July 1946 with the 8th Photo Reconnaissance Squadron based at Johnson AB in Japan. Over the next 30 months the 8th PRS's fleet of Reporters mapped Japan, South Korea, and the Philippines. Only two aircraft were lost in those 30 months, an impressively low-loss rate given the long range nature of the photomapping missions. In addition, the 7th PRS and the 63rd PRS operated clandestine reconnaissance missions from Yokota and Johnson AB in Japan, presumably over Communist-held areas in China, Korea, and possibly over the Soviet Union. 

In June 1948, following the establishment of the US Air Force as independent branch of the military the year prior, the F-for-foto designation was changed to the R-for-reconnaissance prefix and the F-15A become the RF-61C (with F now standing for fighter). The 8th PRS, the main unit that operated the small group of Reporters, was redesignated the 8th Tactical Reconnaissance Squadron as a result of the designation change, but by this point Reporter operations were being drawn down with the first aircraft going into storage. The last RF-61C Reporter was stricken from active duty on 14 March 1950, only three months before the Korean War broke out. 

The non-operational history of the F-15A/RF-61C Reporter included the use of a single aircraft (45-59318) in Operation Thunderstorm from 1946 to 1947 along with several other P-61B Black Widows. This particular Reporter was disposed of by the USAF in November 1949. The first Reporter prototype (45-95300) was used for another 17 months by the USAF and Northrop on a variety of test programs before it was passed onto the National Advisory Committee on Aeronautics (NACA, the predecessor organization of NASA), where it was operated from Moffett Field, California between 1948 and 1950 to carry aloft various test shapes and scale flying models to be dropped from high altitudes. By 1951 when all other Reporters had been scrapped, this first Reporter went on the US civil register as N5093V and even did a short stint in Mexico as XB-FUJ, both times in an aerial spray role. In returned to the United States in the operation of the US Forestry Service as N9768Z where it was modified with a large fire retardant tank under the central crew nacelle. Operated by Aero Enterprises of Fresno, California, on behalf of the USFS, it was nicknamed the "Pregnant Widow" and was lost when it crashed near Hollister, California during a retardant drop on 6 September 1968. 

Source: Air Fan International, September 1996, Volume 1, Number 6. "Northrop Reporter- The first F-15 was no Eagle" by Alain Pelletier, p54-62. 

Despite both the Northrop YB-49 and the B-2 Spirit stealth bomber being of flying wing configuration and even sharing the same wingspan, the YB-49 was never a starting point in the B-2 design process. Early B-2 studies did feature a flying wing as from the beginning Northrop's engineers goal was a configuration with a very low radar cross section and from that basis, that made a flying wing configuration favorable. The engineers had determined that a flying wing was the optimum configuration for getting low radar cross section characteristics in a large aircraft.

According to Irv Waaland, one of the founding engineers who formed the initial design team for the B-2 Spirit in the late 1970s, what the YB-49 provided the B-2 design team was a "feasibility establishment"- the first B-2 configuration studies had vertical tails as part of the flying wing design. But in an era of powered controls and digital flight computers, the B-2 team realized that they could get rid of the vertical tails (which dramatically reduced the RCS of the B-2) as their study of the YB-49 program showed that it had small vestigial vertical fins (smaller than what the initial B-2 configuration studies had, actually) and that was in a day before digital flight control technology.

Because of the unique flying characteristics of the flying wing configuration, Irv Waaland and his team of engineers extensively interviewed the engineers from the YB-49 like William Sears and Irv Ashkenas as well as the chief test pilot in those days, Max Stanley (he had flown the XB-35, the prop-driven antecedent of the YB-49, on its maiden flight).

In fact, Max Stanley was cleared for the B-2 program which was one of the most classified programs at the time. He often flew the flight control simulator and provided input to the design team which saved them extensive time and effort. In one area in particular, the wind tunnel studies of the B-2 suggested that the ground effect would make it difficult to land the B-2 and the engineers were preparing to create a second flight control configuration for the B-2's flight computers that would kick in on landing to overcome this perceived issue.

When this issue was brought to Max Stanley's attention, he had indicated that there were similar fears about the XB-35/YB-49 and that as his impressions in the B-2 sim were that it flew very similarly to the YB-49, he assured the engineers that the B-2 would land just fine. He had convinced the design team to leave out the alternate flight control configuration and sure enough, when the B-2 made its maiden flight in July of 1989, the stealth bomber landed just as Max Stanley had predicted.

Source: Northrop Flying Wings: A History of Jack Northrop's Visionary Aircraft by Garry R. Pape with John M. Campbell. Schiffer Publishing, 1995, p201-204.

The Legacy of the Northrop XP-56 "Black Bullet"

The lasting legacy of the Northrop XP-56 "Black Bullet" isn't its configuration but rather how the development of the aircraft changed the way metal alloys were used in aircraft and that in turn, changed the way metal alloys were handled in other industrial applications outside of aircraft manufacturing. At the time Northrop got the contract to develop the XP-56, aluminum alloy production was insufficient to meet forecast demands for just the aircraft industry alone in the 1939-1940 timeframe. Many manufacturers turned to alternative materials such as Duramold, wood, and even stainless steel.

Jack Northrop, however, always had an interest in advanced materials applications besides unconventional aircraft configurations. While working for Douglas in the 1930s, he got interested in the use of magnesium sheet but because it was a relative unknown in the industry of the day, he got little support from Donald Douglas. When he left Douglas to start his own company in 1939, use of magnesium sheet at the time was considered unworkable as it couldn't be riveted with aluminum alloy rivets due to galvanic corrosion and welding was difficult at best.

But magnesium was abundant in land deposits and seawater and its 2/3 lighter weight than comparable thickness aluminum alloy sheet allowed thicker skins and parts for an equivalent weight. With welding seen as the only viable way of working with magnesium sheet in an aircraft, Northrop hired an associate from Douglas, Vladimir Pavlecka, to develop a way of efficiently and cleanly welding magnesium. The end result of Pavlecka's work resulted in Heliarc welding and the patenting of the Heliarc welding torch which quickly found industrial applications outside of aircraft manufacturing. Northrop and Pavlecka's Heliarc welding eliminated the use of flux or a flux-based electrode as in conventional welding- use of flux on magnesium caused a weak and porous weld seam. Using a tungsten electrode, a stream of helium was used to eliminate atmospheric oxygen from the local environment at the tip of the torch, resulting in a high quality magnesium weld.

On the XP-56, the assembly jigs were used to hold magnesium sheet in place and then the interior was welded to the sheet's inside. So quite literally, the aircraft was built from the outside to the inside! With no rivets, the skin of the XP-56 was very smooth and so stiff that the aircraft didn't even need main wing spars in its design.

In someways developing Heliarc welding was the easiest problem to solve- Northrop's engineers devoted considerable effort into getting good quality magnesium sheet that was flat and the stout assembly jigs and welding fixtures were a first in any industry.

Source: American Secret Pusher Fighters of World War II: XP-54, XP-55, XP-56 by Gerald Balzer. Specialty Press, 2008, p111-126.

The USAF Thunderbirds converted from the F-100 Super Sabre to the F-4E Phantom in 1969 and at the time, it was the most extensive conversion carried out by the demonstration team. Because of the numerous metal alloys used in the Phantom's construction, instead of a baremetal base used previously, a special gloss white polyurethane paint was used as the base color that is still the base color used to this day.

With the 1973 oil crisis, the more economical aircraft was needed and the team transitioned to the Northrop T-38 Talon. The amount of fuel that a single F-4E used in a single air show could fuel five T-38 Talons doing the same show routine.

Source: The McDonnell Douglas F-4 Phantom II- A Comprehensive Guide for the Modeller, Part 1: USAF Variants (Modellers Datafile 12) by Andy Evans. SAM Publications, 2007, p104.

On the last night of World War II, a Northrop P-61 Black Widow from the 548th Night Fighter Squadron from Ie Shima was on nocturnal patrol and in low-altitude pursuit of a Japanese fighter when the enemy aircraft hit the water before the Black Widow could fire a shot. The war officially ended at midnight that night, but there remained the possibility of kamikaze attacks on American airfields despite the surrender, so the P-61s remained on alert.

The following night on August 15, another P-61 was vectored by ground control on Saipan towards another Japanese fighter flying at low level. This time the Japanese pilot was dropping window to confuse the Black Widow's radar operator. Like the previous night, a low altitude pursuit ensued, but before the P-61 could open fire, the plane impacted the water.

The P-61 Black Widow in effect made the final two kills of World War II without firing its guns!

Source: Aviation History, November 2008. "Bite of the Black Widow: Northrop's P-61 was the ultimate nocturnal predator in the Pacific War" by Warren Thompson, p54-55.

The Northrop Gamma started out in 1933 as a private venture involving the latest advances in structural techniques that influenced later generations of aircraft. Later to be designated the A-17, the last military version to bear the name Gamma was the Gamma 5. Only three were built before Northrop switched over production the A-17.

The first Gamma 5 was sold with US government approval to Japan in October 1935. Shipped to Japan the following month, it was evaluated by both Mitsubishi and Nakajima on behalf of the Imperial Japanese Navy and designated the BXN1.

The third Gamma 5 was shipped (again with US government approval) to the Imperial Japanese Navy and designated by the IJN as the BXN2. It was then turned over to Nakajima for further evaluation and is believe to have influenced the design of the Nakajima B5N "Kate" torpedo bomber.

Source: Aerospace Modeler Magazine, No. 7/Summer 2007. "The Northrop Military Gamma Family: Part 1" by Geoff Hays, p36.

The first generation of UAVs had their start with Leigh Dugmore Denny, a Hollywood actor with Paramount Studios. Denny had a passion for radio-controlled aircraft and even opened a hobby shop on Hollywood Boulevard. In 1934 he founded Denny Industries to build RC model planes and quickly realized that there would be military potential for his models. The following year he founded Radioplane Company and would later secure a large contract to build aerial targets during the Second World War.

In 1952 Radioplane was acquired by Northrop and became the Radioplane Division and by the 1960s, it would be renamed the Ventura Division of Northrop, still engaged in the manufacture of UAV aircraft. In 1968, the year after Denny passed away, the Ventura Division delivered the first MQM-74/BQM-74 Chukar to the US Navy. By the time of Operation Iraqi Freedom, over 5000 Chukar UAVs had been built. Some were even used in Desert Storm as well as Iraqi Freedom to lay chaff corridors for inbound strike aircraft.

Source: Attack of the Drones: A History of Unmanned Aerial Combat by Bill Yenne. Zenith Press, 2004, p15-31.

On both the Northrop XB-35 and YB-49 flying wing bombers, the pilot sat in an elevated position offset to the left using a bubble canopy. The co-pilot sat lower on the right inside the wing and looked forward through windows in the leading edge of the wing just to the right of the center. On the XB-35, there was a single set of throttles with four levers and on the YB-49 there was also a single set of throttles, but with two levers- one for the three jet engines in each wing.

Unfortunately, only the pilot could use the throttles as they were out of reach for the co-pilot who sat in the lower position in the wing. That meant that the co-pilot could neither takeoff or land the large flying wing bombers.

Source: Northrop Flying Wings: A History of Jack Northrop's Visionary Aircraft by Garry R. Pape with John M. Campbell. Schiffer Publishing, 1995, p156.