In
1969, an F-101F proficiency trainer assigned to the 123rd TRW at
Richards-Gebaur AFB crashed at Buckley ANGB, CO, injuring pilots Lt. Col Mervin
Johnson and Capt. John Molini of the 192nd TRS, Nevada ANG. The accident occurred not before an order to
deactivate the 123rd TRW and demobilize the attached Air Guard units
with after the repatriation of the crew of the captured USS Pueblo.
Friday, February 27, 2015
Thursday, February 26, 2015
This Day in McDonnell Voodoo History, February 25th:
In 1955, the IF-101A interceptor program was
officially endorsed by Headquarters USAF.
This would lead to the F-101B version that served into the mid-1980s.
Photo: The IF-101A was one of two different Voodoo interceptor proposals considered for production as a backstop to the continually delayed F-102 program. While the proposed IF-101B had systems more along the lines of the "ultimate" F-102B interceptor (to become the F-106), The IF-101A was a minimum-change version of the basic F-101A that would borrow the fire control system and armament of the "interim" F-102A to provide a high-performance long-range interceptor with a relative minimum of technical risk. Within a short period of time, the IF-101A concept would undergo rapid evolution. Here, the J57-P-13 engines and "pitch-up fillets" that first appeared on Block 15 F-101A aircraft are visible.
Photo Credit: McDonnell Douglas via Bert Kinsey / Detail & Scale
Photo: The IF-101A was one of two different Voodoo interceptor proposals considered for production as a backstop to the continually delayed F-102 program. While the proposed IF-101B had systems more along the lines of the "ultimate" F-102B interceptor (to become the F-106), The IF-101A was a minimum-change version of the basic F-101A that would borrow the fire control system and armament of the "interim" F-102A to provide a high-performance long-range interceptor with a relative minimum of technical risk. Within a short period of time, the IF-101A concept would undergo rapid evolution. Here, the J57-P-13 engines and "pitch-up fillets" that first appeared on Block 15 F-101A aircraft are visible.
Photo Credit: McDonnell Douglas via Bert Kinsey / Detail & Scale
Wednesday, February 18, 2015
Black Magic: The Unknown History of the Voodoo
58 years after it was written, the official history of the development of the McDonnell F-101 Voodoo remains classified. However, since the mid 1990s, a great deal about the airplane and its original mission has come to light.
In the Fall of 1945, the bombers of the United States Army Air Force represented by far the most potent military force in history. Having delivered the atomic bomb over Hiroshima and Nagasaki, the waves of hundreds of huge, silver B-29s over all of the major cities in Japan were in the process of being forgotten. Japanese cities were incinerated by the square mile with the most advanced and expensive aircraft in the world, a true marvel of aerodynamic design. Three years later, that capability had almost completely evaporated as the new commander of what was now Strategic Air Command, General Curtiss LeMay, began the onerous task of reforging the broken sword of American strategic airpower into a potent new weapon with which to face the newly-realized threat of Soviet expansion.
Beginning with his command of the first American bomber group deployed to England to take the war to Germany and as he advanced to commands within the Eighth Air Force and, finally, the 21st Air Force charged with the destruction of targets in Japan, LeMay understood better than anyone the potential of strategic airpower and what was needed to not only ensure that units and equipment were mission-capable, but also what was needed to keep his precious crews alive. During the air war over Germany, one of the decisive innovations was to use long-range fighters to provide escort for the slow, heavy bombers to their targets and back, fending off the vicious attacks of the Luftwaffe. While the technology had changed drastically with the dawn of the jet age, the basic concepts of strategic bombardment had not. Increasing numbers of ever more swift jet interceptors were being fielded and it would only be a matter of time before the Soviet Union developed effective interceptors of their own.
General LeMay wanted a fighter force under his sole and direct operational control, with no other mission but to provide escort and support for his forward-deployed B-29 and B-50 bombers, as well as for the gargantuan Convair B-36 and the swift, high-flying B-47. In October 1948, he summoned the one fighter pilot on his staff, Lieutenant Colonel William "Dinghy" Dunham, to draft a letter detailing the specifications for a new, purpose-built fighter. As time passed and nuclear weapons technology proceeded at a breakneck pace, new miniaturized weapons suitable for fighter carriage became feasible. Afforded the capability of striking air defense and other targets in support of following bombers, the new nuclear-capable fighters enabled the "strategic fighter" concept to be born. Dunham's proposal led to the selection of a developed version of the canceled McDonnell XF-88A Voodoo. As the design evolved, it would become the ultimate expression of the strategic fighter concept as the F-101A.
Photo: Mock-up of the McDonnell Model 36W, the F-88K, soon to be recast as the F-101A.
Photo credit: Gerald Balzer Collection, Greater St. Louis Air & Space Museum
While Tactical Air Command was developing its own nuclear delivery capability, it used relatively small, low-yield weapons such as the 20-kiloton MK 7 and 15-kiloton MK 8. The interim F-84G and F-84F fighters assigned to strategic fighter wings used the same weapons, since they were all that were available and nothing larger could be carried. SAC wanted the ultimate expression of its strategic fighter to have commensurate firepower. The smallest and lightest strategic-level weapon available was the new MK 5 weapon, intended for relatively short-ranged B-50 and B-47 medium bombers. With six selectable yields ranging from 20 kT to 120 kT, the MK 5 was just small enough that it could, conceivably, be carried by a large fighter airplane. In 1953, while the new F-101A was well into design development, the concept of modifying the F-101A to carry the 44-inch diameter W-5 warhead in a streamlined casing was explored. The concept was deemed feasible and the F-101A was modified to accommodate the large, 33 foot long, 10,000 pound store on a centerline hook. By June 1954, the lightweight TX-15 Zombie hydrogen weapon and another weapon that remains classified were also being considered for the new Model 96 store, to be manufactured by McDonnell. In any event, it promised the Voodoo far greater firepower than any fighter aircraft before or since. Ranging out nearly 1,000 miles from base, air-refuelable, and with a top speed of over 1,000 miles-per-hour, the reincarnated version of the Voodoo would form SAC's irresistible sledgehammer to breach the defenses on the approaches to Moscow and other targets within the heart of the Soviet Union.
Photo: Concept drawing of the F-101A/XW-5 weapon system, April 1953.
Photo credit: US Department of Energy
Drop testing of the Model 96 pod began in 1954 from a B-47 test aircraft. By the late Spring of 1955, testing was ready to begin on preproduction F-101A aircraft. The history of flight testing of the weapon remains classified, but much can be gleaned about it. During 1955, the F-101A was plagued with compressor stalls under any form of accelerated flight condition, as the year wore on and both engines and airframe were tweaked to problem gradually improved. However, an insidious and far more dangerous problem lay ahead as the stall-free maneuvering envelope of the airplane was expanded--the infamous "pitch-up" of the Voodoo, which led to its first fatality in December 1955 with the loss of Captain John Dolan near Edwards AFB, California. Already "squirrelly" at combat altitude and heavy fuel load, any handling deficiencies could only have been exacerbated by the presence of a large, heavy centerline pod. The side area of the pod nearly doubled the area that the vertical tail had to hold stable, its cross-sectional area made a poor Area Rule distribution even worse, and the increased angle-of-attack needed to produce lift to counteract the weight of the Model 96 shape, ranging between 10,000 pounds with a full 849-gallon load of fuel and 4,000-pound empty drop weight would have brought the F-101A even closer to the razor's edge of the pitch-up boundary under cruise and even the most benign maneuvering conditions.
Photo: Special weapons test aircraft JF-101A 52-2427 after takeoff during a later test flight with the Model 96 store. The large size of the pod with respect to the small wings and control surfaces of the Voodoo is particularly noteworthy.
Photo credit: Gerald Balzer Collection, Greater St. Louis Air & Space Museum
As an integral part of the WS-105A weapon system, McDonnell made valiant efforts to salvage the pod concept. McDonnell had envisioned a modular concept in which different capabilities could be added to the basic F-101A by interchangeable pods with different mission equipment. A developed version of the pod, the McDonnell Model 102, could carry various types of buddy-refueling equipment and in the Model 102H and Model 102J electronic countermeasures equipment. The jammers specified for the Model 102H, the AN/ALT-6, AN/ALT-7, and AN/ALT-8 along with an AN/ALE-1 chaff dispenser, comprised the new SAC-standard ECM systems being retrofitted at that time to the B-47 and B-52 fleets. The last gasp for the pod concept came in March 1956 with the Model 117A store, intended for carriage by both F-101A fighters and RF-101A reconnaissance aircraft. Carrying similar equipment to the Model 102H, its development was discontinued along with all of the other pod concepts that same month. Integration of the basic Model 96 store with the lightweight, 2 MT yield W-27 was also halted.
By early 1956, it had become clear that the F-101A would be unsuitable for the strategic fighter mission envisioned for it. Indeed, with the deployment of the fast, very high-flying B-52 and the switch from high altitude penetration to low-altitude missions for the workhorse B-47, the entire strategic fighter concept was rendered obsolete. State-of-the-art just a few years prior, the W-5 warhead was on its way to becoming a museum piece. New weapons on the horizon such as the small TX-28 hydrogen bomb promised greater yield with much lower drag and better range performance than the massive Model 96 pod. Originally intended to equip at least three fighter wings for SAC, the F-101A and improved F-101C were deployed with only a single combat wing, the 27th Strategic Fighter Wing at Bergstrom AFB, Texas beginning in May 1957. SAC operated the Voodoo for only two months as plans were already in motion to transfer it to a less than enthusiastic Tactical Air Command and get out of the fighter business altogether. Plagued with troubles and with its future far from certain at that point, the Voodoo would go on to make history and become one of the key assets of American national policy during the most critical years of the Cold War.
Photo: The second special weapons test aircraft, 53-2428, carrying a T-63 "shape" for the interim MK 7 weapon. Standard for the tactical nuclear strike role in the late 1950s, the Voodoo would go on to carry the MK 28 weapon as its mainstay over most of its active USAF service. The powerful megaton-range MK 43 "laydown" weapon would also later be carried, but was primarily issued to the RF-101C Voodoos of the 38th TRS, which had assumed a secondary nuclear strike role in the aftermath of the Berlin Crisis of 1961.
Photo Credit: Gerald Balzer Collection, St. Louis Air & Space Museum
In the Fall of 1945, the bombers of the United States Army Air Force represented by far the most potent military force in history. Having delivered the atomic bomb over Hiroshima and Nagasaki, the waves of hundreds of huge, silver B-29s over all of the major cities in Japan were in the process of being forgotten. Japanese cities were incinerated by the square mile with the most advanced and expensive aircraft in the world, a true marvel of aerodynamic design. Three years later, that capability had almost completely evaporated as the new commander of what was now Strategic Air Command, General Curtiss LeMay, began the onerous task of reforging the broken sword of American strategic airpower into a potent new weapon with which to face the newly-realized threat of Soviet expansion.
Beginning with his command of the first American bomber group deployed to England to take the war to Germany and as he advanced to commands within the Eighth Air Force and, finally, the 21st Air Force charged with the destruction of targets in Japan, LeMay understood better than anyone the potential of strategic airpower and what was needed to not only ensure that units and equipment were mission-capable, but also what was needed to keep his precious crews alive. During the air war over Germany, one of the decisive innovations was to use long-range fighters to provide escort for the slow, heavy bombers to their targets and back, fending off the vicious attacks of the Luftwaffe. While the technology had changed drastically with the dawn of the jet age, the basic concepts of strategic bombardment had not. Increasing numbers of ever more swift jet interceptors were being fielded and it would only be a matter of time before the Soviet Union developed effective interceptors of their own.
General LeMay wanted a fighter force under his sole and direct operational control, with no other mission but to provide escort and support for his forward-deployed B-29 and B-50 bombers, as well as for the gargantuan Convair B-36 and the swift, high-flying B-47. In October 1948, he summoned the one fighter pilot on his staff, Lieutenant Colonel William "Dinghy" Dunham, to draft a letter detailing the specifications for a new, purpose-built fighter. As time passed and nuclear weapons technology proceeded at a breakneck pace, new miniaturized weapons suitable for fighter carriage became feasible. Afforded the capability of striking air defense and other targets in support of following bombers, the new nuclear-capable fighters enabled the "strategic fighter" concept to be born. Dunham's proposal led to the selection of a developed version of the canceled McDonnell XF-88A Voodoo. As the design evolved, it would become the ultimate expression of the strategic fighter concept as the F-101A.
Photo: Mock-up of the McDonnell Model 36W, the F-88K, soon to be recast as the F-101A.
Photo credit: Gerald Balzer Collection, Greater St. Louis Air & Space Museum
While Tactical Air Command was developing its own nuclear delivery capability, it used relatively small, low-yield weapons such as the 20-kiloton MK 7 and 15-kiloton MK 8. The interim F-84G and F-84F fighters assigned to strategic fighter wings used the same weapons, since they were all that were available and nothing larger could be carried. SAC wanted the ultimate expression of its strategic fighter to have commensurate firepower. The smallest and lightest strategic-level weapon available was the new MK 5 weapon, intended for relatively short-ranged B-50 and B-47 medium bombers. With six selectable yields ranging from 20 kT to 120 kT, the MK 5 was just small enough that it could, conceivably, be carried by a large fighter airplane. In 1953, while the new F-101A was well into design development, the concept of modifying the F-101A to carry the 44-inch diameter W-5 warhead in a streamlined casing was explored. The concept was deemed feasible and the F-101A was modified to accommodate the large, 33 foot long, 10,000 pound store on a centerline hook. By June 1954, the lightweight TX-15 Zombie hydrogen weapon and another weapon that remains classified were also being considered for the new Model 96 store, to be manufactured by McDonnell. In any event, it promised the Voodoo far greater firepower than any fighter aircraft before or since. Ranging out nearly 1,000 miles from base, air-refuelable, and with a top speed of over 1,000 miles-per-hour, the reincarnated version of the Voodoo would form SAC's irresistible sledgehammer to breach the defenses on the approaches to Moscow and other targets within the heart of the Soviet Union.
Photo: Concept drawing of the F-101A/XW-5 weapon system, April 1953.
Photo credit: US Department of Energy
Drop testing of the Model 96 pod began in 1954 from a B-47 test aircraft. By the late Spring of 1955, testing was ready to begin on preproduction F-101A aircraft. The history of flight testing of the weapon remains classified, but much can be gleaned about it. During 1955, the F-101A was plagued with compressor stalls under any form of accelerated flight condition, as the year wore on and both engines and airframe were tweaked to problem gradually improved. However, an insidious and far more dangerous problem lay ahead as the stall-free maneuvering envelope of the airplane was expanded--the infamous "pitch-up" of the Voodoo, which led to its first fatality in December 1955 with the loss of Captain John Dolan near Edwards AFB, California. Already "squirrelly" at combat altitude and heavy fuel load, any handling deficiencies could only have been exacerbated by the presence of a large, heavy centerline pod. The side area of the pod nearly doubled the area that the vertical tail had to hold stable, its cross-sectional area made a poor Area Rule distribution even worse, and the increased angle-of-attack needed to produce lift to counteract the weight of the Model 96 shape, ranging between 10,000 pounds with a full 849-gallon load of fuel and 4,000-pound empty drop weight would have brought the F-101A even closer to the razor's edge of the pitch-up boundary under cruise and even the most benign maneuvering conditions.
Photo: Special weapons test aircraft JF-101A 52-2427 after takeoff during a later test flight with the Model 96 store. The large size of the pod with respect to the small wings and control surfaces of the Voodoo is particularly noteworthy.
Photo credit: Gerald Balzer Collection, Greater St. Louis Air & Space Museum
As an integral part of the WS-105A weapon system, McDonnell made valiant efforts to salvage the pod concept. McDonnell had envisioned a modular concept in which different capabilities could be added to the basic F-101A by interchangeable pods with different mission equipment. A developed version of the pod, the McDonnell Model 102, could carry various types of buddy-refueling equipment and in the Model 102H and Model 102J electronic countermeasures equipment. The jammers specified for the Model 102H, the AN/ALT-6, AN/ALT-7, and AN/ALT-8 along with an AN/ALE-1 chaff dispenser, comprised the new SAC-standard ECM systems being retrofitted at that time to the B-47 and B-52 fleets. The last gasp for the pod concept came in March 1956 with the Model 117A store, intended for carriage by both F-101A fighters and RF-101A reconnaissance aircraft. Carrying similar equipment to the Model 102H, its development was discontinued along with all of the other pod concepts that same month. Integration of the basic Model 96 store with the lightweight, 2 MT yield W-27 was also halted.
By early 1956, it had become clear that the F-101A would be unsuitable for the strategic fighter mission envisioned for it. Indeed, with the deployment of the fast, very high-flying B-52 and the switch from high altitude penetration to low-altitude missions for the workhorse B-47, the entire strategic fighter concept was rendered obsolete. State-of-the-art just a few years prior, the W-5 warhead was on its way to becoming a museum piece. New weapons on the horizon such as the small TX-28 hydrogen bomb promised greater yield with much lower drag and better range performance than the massive Model 96 pod. Originally intended to equip at least three fighter wings for SAC, the F-101A and improved F-101C were deployed with only a single combat wing, the 27th Strategic Fighter Wing at Bergstrom AFB, Texas beginning in May 1957. SAC operated the Voodoo for only two months as plans were already in motion to transfer it to a less than enthusiastic Tactical Air Command and get out of the fighter business altogether. Plagued with troubles and with its future far from certain at that point, the Voodoo would go on to make history and become one of the key assets of American national policy during the most critical years of the Cold War.
Photo: The second special weapons test aircraft, 53-2428, carrying a T-63 "shape" for the interim MK 7 weapon. Standard for the tactical nuclear strike role in the late 1950s, the Voodoo would go on to carry the MK 28 weapon as its mainstay over most of its active USAF service. The powerful megaton-range MK 43 "laydown" weapon would also later be carried, but was primarily issued to the RF-101C Voodoos of the 38th TRS, which had assumed a secondary nuclear strike role in the aftermath of the Berlin Crisis of 1961.
Photo Credit: Gerald Balzer Collection, St. Louis Air & Space Museum
Monday, February 16, 2015
Something Extra: My next project--The McDonnell F3H Demon
It's natural during the course of any research project to read up on a lot of subjects that have nothing directly to do with the task at hand, but that provide vital context and are interesting in their own right. In some cases, the source documentation needed to expand on one of these little "rabbit holes" is fragmentary with much important information lost. But in others, even when there have been recently-published titles, sometimes by sheer luck you find small, but very important nuggets that have been missed and provide an opportunity to tell not only a more complete story, but use that story to talk about a lot of other things along the way. This was the approach that I used with my recent book on the McDonnell F-101. I got to talk about key developments that opened the road to Mach 2, the realities of nuclear testing, nuclear weapons design, and peel back the placid memory veil covering the Eisenhower years and reveal just how dangerous those times were, and how rapidly things escalated to the brink of nuclear war on two occasions during the subsequent Kennedy administration. In a more subtle manner, I was also able to draw attention to parallels between the mindset and decision-making process of Kennedy, his inner circle, and its relationship with military authorities with that of the current Obama administration. History is useless if it does not illuminate the past to guide the future.
A few months back, I received a gratis copy of a new book on the F3H Demon by my friend Tony Buttler. (You can read an excellent review here: http://thanlont.blogspot.com/2014/11/warpaint-series-no-99-mcdonnell-f3h.html). Since I had at least some familiarity with it as it was built by McDonnell side-by-side with the F-101, he asked me to comment on it. Fortunately, I had a couple of books covering the F3H in my library as well as some files related to engine development and the like. Tony's book is intended more for modelers, but he encouraged me to write a more comprehensive technical history along the lines of the F-101 book. I began to write an outline, knowing that there was another more comprehensive book as the opening title of the return of Bert Kinsey's outstanding Detail & Scale series...now available as digital books far superior to the already-renowned paperbacks published in the 1980s and 1990s (available here: http://www.detailandscale.com/f3h_demon_digital_book.html). His series of books have been invaluable over the years, and with a new digital format that allows as many pages of material as desired, what could I possibly add?
My usual procedure is to take all of the information that I can find from every source available and fit it all into a master time line. This approach has proven very useful in establishing connections and patterns to guide further research and hopefully tell a compelling story, as well as to vet information and check for typos or just flat-out bad information. But as I began fitting the pieces together and filling them out, I remembered something that I had seen several years ago on the NASA Technical Reports Server. In an old report that I ran across, I saw a wind tunnel model of the distinctive fuselage and inlet duct design of the F3H. I rediscovered that report and much more, finding that those studies were first commissioned just after World War 2, and at least two years before the Navy announced its competition for a high-performance interceptor that would become the McDonnell F3H. This had been missed.
Photo of transonic axisymmetric inlet model, circa late 1946. Source: NACA Technical Note 2684.
The travails of engine development for the F3H have long been documented, and in the mid-1950s made national headlines under the blinding scrutiny of a Congressional inquiry. The original Westinghouse J40, which turned out to be a truly worthless piece of hardware, was replaced by the workable, if only marginally better, Allison J71. With the J71, the production F3H-2 version proved to be severely underpowered. But the funny thing was, I had seen several photographs of the airplane in full afterburner. Each of the photos showed clear "shock diamonds" in the afterburner plume. These can only be produced if the exhaust gases are exiting the nozzle at supersonic speed, which in turn could only be produced by an advanced convergent-divergent nozzle. Hmmm.... Kinsey's book shows excellent details of the exhaust nozzle of an F3H-2 in a museum. It is clearly a convergent-divergent nozzle design and would have been among the first (if not the first) production turbojet engines so equipped. This has not been mentioned nor explored before. If the J71 was a "dog" with such a nozzle, what would it have been like with a conventional, sonic-limited convergent nozzle? Something else to write about....
The F3H was recast with new armament, switching from a combination of 20-millimeter cannons and unguided rockets to cannons and the first production guided air-to-air missiles, the Sperry AAM-N-2 Sparrow I. Not much has been written about this. The Sparrow I has always been considered a failure (and it was) but as the first deployable interceptor missile system, its development deserves to be covered in detail. No such study has been published. Other F3H-2 subvariants were equipped with early naval tactical nuclear weapons as well as much improved Sparrow III missiles. The missiles and the Westinghouse radar and fire control system were carried over into the legendary McDonnell F4H-1 Phantom. Much ink has been expended on the story of the Phantom, and justifiably so. But little has been written on the development of this key component of its armament system. An understanding of the development of this system is critical to understanding more modern and even current developments in radar-guided air-to-air missile and fire control systems. A thorough treatment of this story could fill a small but critical role for those trying to achieve that understanding. So, more to write about....
The enemy, of course, is time. But the stories have to be told, and the muse--that beautiful bitch!--can never be denied for long! So, it looks as though another book is in my future.
A few months back, I received a gratis copy of a new book on the F3H Demon by my friend Tony Buttler. (You can read an excellent review here: http://thanlont.blogspot.com/2014/11/warpaint-series-no-99-mcdonnell-f3h.html). Since I had at least some familiarity with it as it was built by McDonnell side-by-side with the F-101, he asked me to comment on it. Fortunately, I had a couple of books covering the F3H in my library as well as some files related to engine development and the like. Tony's book is intended more for modelers, but he encouraged me to write a more comprehensive technical history along the lines of the F-101 book. I began to write an outline, knowing that there was another more comprehensive book as the opening title of the return of Bert Kinsey's outstanding Detail & Scale series...now available as digital books far superior to the already-renowned paperbacks published in the 1980s and 1990s (available here: http://www.detailandscale.com/f3h_demon_digital_book.html). His series of books have been invaluable over the years, and with a new digital format that allows as many pages of material as desired, what could I possibly add?
My usual procedure is to take all of the information that I can find from every source available and fit it all into a master time line. This approach has proven very useful in establishing connections and patterns to guide further research and hopefully tell a compelling story, as well as to vet information and check for typos or just flat-out bad information. But as I began fitting the pieces together and filling them out, I remembered something that I had seen several years ago on the NASA Technical Reports Server. In an old report that I ran across, I saw a wind tunnel model of the distinctive fuselage and inlet duct design of the F3H. I rediscovered that report and much more, finding that those studies were first commissioned just after World War 2, and at least two years before the Navy announced its competition for a high-performance interceptor that would become the McDonnell F3H. This had been missed.
Photo of transonic axisymmetric inlet model, circa late 1946. Source: NACA Technical Note 2684.
The travails of engine development for the F3H have long been documented, and in the mid-1950s made national headlines under the blinding scrutiny of a Congressional inquiry. The original Westinghouse J40, which turned out to be a truly worthless piece of hardware, was replaced by the workable, if only marginally better, Allison J71. With the J71, the production F3H-2 version proved to be severely underpowered. But the funny thing was, I had seen several photographs of the airplane in full afterburner. Each of the photos showed clear "shock diamonds" in the afterburner plume. These can only be produced if the exhaust gases are exiting the nozzle at supersonic speed, which in turn could only be produced by an advanced convergent-divergent nozzle. Hmmm.... Kinsey's book shows excellent details of the exhaust nozzle of an F3H-2 in a museum. It is clearly a convergent-divergent nozzle design and would have been among the first (if not the first) production turbojet engines so equipped. This has not been mentioned nor explored before. If the J71 was a "dog" with such a nozzle, what would it have been like with a conventional, sonic-limited convergent nozzle? Something else to write about....
The F3H was recast with new armament, switching from a combination of 20-millimeter cannons and unguided rockets to cannons and the first production guided air-to-air missiles, the Sperry AAM-N-2 Sparrow I. Not much has been written about this. The Sparrow I has always been considered a failure (and it was) but as the first deployable interceptor missile system, its development deserves to be covered in detail. No such study has been published. Other F3H-2 subvariants were equipped with early naval tactical nuclear weapons as well as much improved Sparrow III missiles. The missiles and the Westinghouse radar and fire control system were carried over into the legendary McDonnell F4H-1 Phantom. Much ink has been expended on the story of the Phantom, and justifiably so. But little has been written on the development of this key component of its armament system. An understanding of the development of this system is critical to understanding more modern and even current developments in radar-guided air-to-air missile and fire control systems. A thorough treatment of this story could fill a small but critical role for those trying to achieve that understanding. So, more to write about....
The enemy, of course, is time. But the stories have to be told, and the muse--that beautiful bitch!--can never be denied for long! So, it looks as though another book is in my future.
This Day in McDonnell Voodoo History, February 16th:
In 1953, conversion of the first VooDoo prototype to the XF-88B had been
completed, and the first ground run of the new Allison XT38-A-5 turboprop
engine took place. The new engine ran
successfully for 29 minutes during the initial test run.
On the same date in 1955, procurement of two Y/IF-101A and 26 IF-101A interceptor versions of the VooDoo was authorized.
Also, in 1971, the last 13 active USAF RF-101s, all A-model aircraft, were transferred to the 191st TRG of the Michigan Air National Guard from the 31st TRTS of the 363rd TRW.
On the same date in 1955, procurement of two Y/IF-101A and 26 IF-101A interceptor versions of the VooDoo was authorized.
Also, in 1971, the last 13 active USAF RF-101s, all A-model aircraft, were transferred to the 191st TRG of the Michigan Air National Guard from the 31st TRTS of the 363rd TRW.
This Day in McDonnell Voodoo History, February 14th:
In 1947, a revised McDonnell XP-88 design was
approved for production by Air Materiel Command. The most conspicuous change was the change
from the unusual “Vee” tail of the original design to a more conventional
arrangement. The contract specified an
estimated cost of $5,014,191.10 along with a fee of $285,808.90.
This is a photo of the original Model 36C Voodoo mock-up, inspected in August 1946. The "Vee" tail design saved precious weight, critical to the range and altitude performance of a long-range fighter. However, subsequent wind tunnel testing revealed possible interference effects at transonic speed. A conventional tail was chosen instead and would be built as the definitive XF-88 Voodoo.
Photo Credit: NARA via Tony Buttler
This is a photo of the original Model 36C Voodoo mock-up, inspected in August 1946. The "Vee" tail design saved precious weight, critical to the range and altitude performance of a long-range fighter. However, subsequent wind tunnel testing revealed possible interference effects at transonic speed. A conventional tail was chosen instead and would be built as the definitive XF-88 Voodoo.
Photo Credit: NARA via Tony Buttler
Thursday, February 12, 2015
This Day in McDonnell Voodoo History, February 12th:
In 1952, McDonnell proposed a reconnaissance
derivative of the new F-101A, equipped with the new, high-resolution KA-1
camera. Circumspect about the idea, the
USAF subsequently considered an interchangeable reconnaissance nose carrying
cameras instead of radar and guns.
On the same day in 1966, a pair of RF-101Cs that were apparently several miles inside the Chinese border with North Vietnam at 40,000 feet sighted a pair of fast-moving contrails coming toward them on a southerly heading, which then made an abrupt turn to the west. Although no positive ID could be made, they were suspected to be Chinese MiGs.
On the same day in 1966, a pair of RF-101Cs that were apparently several miles inside the Chinese border with North Vietnam at 40,000 feet sighted a pair of fast-moving contrails coming toward them on a southerly heading, which then made an abrupt turn to the west. Although no positive ID could be made, they were suspected to be Chinese MiGs.
Wednesday, February 11, 2015
Daniel "Chappie" James: Voodoo pilot
There are a number of notable pilots who have flown the F-101 Voodoo over the years, but none advanced so far as Daniel James, better known by his nickname, "Chappie."
Born in 1920, James began studies at the Tuskegee Institute, completing civilian flight training along with earning his Bachelor's degree in 1942. Remaining at Tuskegee as a flight instructor, Chappie joined the Aviation Cadet program of what was then the Army Air Forces and received his commission in 1943. While the famed "Red Tails" of the 99th Fighter Squadron went to war under the command of Benjamin O. Davis, Chappie James remained stateside. His turn at combat would come in Korea after the Communist armies of dictator Kim Il-sung invaded South Korea to "unify" the peninsula under Communist rule. As a flight leader in the 12th Fighter-Bomber Squadron of the 18th Fighter-Bomber Wing, Chappie flew 101 combat missions in piston-engine F-51 Mustang and, after unit conversion, jet-powered F-80 Shooting Star fighters. As there was negligible air opposition, most of his missions were hazardous close air support sorties flown in defense of United Nations troops.
In July 1951, Chappie was rotated stateside and assigned to fly all-weather interceptors with the 58th Fighter-Interceptor Squadron. This would mark the beginning of a long personal association with air defense. Chappie soon worked his was up to become the squadron operations officer. By 1953, Chappie had moved up the ladder to take his first command as squadron commander of the 437th Fighter-Interceptor Squadron assigned an all-weather interceptor mission under Air Defense Command. One of the pilots that I interviewed for my book, Harry Schmidt, was assigned to his squadron as a young USAF captain. He has nothing but good things to say about his former commander, and feels that he was an excellent pilot and a fair and able leader. After another command billet as CO of the 60th Fighter-Interceptor Squadron, Chappie was selected to attend the Air Command and Staff College, the first step toward advanced rank. After graduating in the summer of 1957, Chappie was assigned to a staff position in the Air defense Division at the Pentagon.
During Chappie's time at the Pentagon, the sole F-101 wing in Tactical Air Command, the 27th Tactical Fighter Wing, was given orders to deploy its men and aircraft to stand nuclear alert with the 81st Tactical Fighter Wing based in England, replacing their obsolescent F-84F Thunderstreak fighter-bombers. A staff of officers containing among some of the Air Force's best fighter tacticians was led by their legendary operations officer, Lt. Col. William D. "Dinghy" Dunham, who as an officer assigned to Strategic Air Command in the late 1940s wrote the original letter detailing what would later become the F-101 Voodoo. Chappie James joined this select group in the summer of 1960, initially as assistant director of operations to Lt. Col. Dunham. When Dunham left to assume command of the 479th Tactical Fighter Wing, equipped with the hot new Lockheed F-104C Starfighter, Chappie assumed his responsibilities as the wing director of operations for the 81st TFW. The F-101 had been introduced to Europe in 1959, over the strong objections of the commanding general of United States Air Forces Europe (USAFE), who wanted all of his tactical fighter-bomber units to be equipped with the new F-100D. Dunham and his squadron commanders worked hard to adapt their blistering-fast mounts into NATO's first effective all-weather strike aircraft.
Having learned at the feet of the master and now as director of operations, it was Chappie's job to develop concepts of operation and specific plans to attack Soviet and Soviet-bloc targets with fighter-borne nuclear weapons. Although very similar to the F-100D in low-level performance, the radar-equipped F-101A and F-101C fighters assigned to the 81st TFW could run in on their targets at 500 feet and below, even in adverse weather and had a 200-nautical-mile range advantage over the F-100. Based on the far eastern coast of Suffolk, England at the "Twin Bases" of RAF Bentwaters and RAF Woodbridge, the Voodoos were within striking distance of the heart of Soviet air defenses guarding the approaches to Moscow. Chappie constantly reviewed and adjusted plans to attack these vital targets in the Baltic States of Lithuania, Latvia, and Estonia as well as the Leningrad District in European Russia. In the event of a general war with the Soviet Union, Chappie carried the responsibility of ensuring that the Voodoos of the 81st TFW could successfully "kick in the doors" and allow the heavy bombers of Strategic Air Command to pour through the breach and into their targets in the Soviet heartland. Considered by many to be the best unit in the USAF, Chappie's job was to make sure that the point of NATO's spear remained razor sharp.
It was during his tenure with the 81st TFW that Chappie would make a life-changing acquaintance when Col. Robin Olds, World War 2 double-ace and considered a maverick within the Air Force, assumed command of the 81st TFW. Olds was considered by many to be a throwback, a fierce and fun-loving warrior-leader within an increasingly technocratic Air Force culture. Chappie had already established a reputation as an excellent staff officer but also recognized a fellow natural leader in Olds, and the two formed a fast friendship. Chappie was soon promoted to squadron commander of the wing's 92nd TFS and then to deputy commander of operations. Together, he and Olds worked together to burnish the reputation and esprit-de-corps of the 81st TFW to even greater heights. In 1964, Chappie was assigned to the same position in a prestigious slot with the 4453rd Combat Crew Training Wing, which was the USAF unit that introduced the new F-4 Phantom to waiting fighter crews. It was during this time that Olds had pushed things a little too far with USAFE leadership--by his own design. Knowing that he was in line for promotion to brigadier general and wanting to lose an opportunity for a combat command in Vietnam, he had trained a demonstration team composed of the best of his pilots to fly daring Thunderbirds-style in the notoriously touchy and unforgiving Voodoo. Narrowly avoiding a court martial, Olds was sent stateside to cool off while he maneuvered for an opportunity to once again lead young fighter pilots in combat.
Within six months of his dressing down by USAFE commanding general Disosway, Olds had taken command of the hard-luck 8th Tactical Fighter Wing at Ubon airbase in Thailand. Overall morale was low within the unit, but among the staff and squadron commanders there were many individuals who held considerable promise. Olds was not only aggressive and decisive, but also an astute judge of character. While he was the quintessential combat-leader, he recognized that what really made any unit tick and function properly was a good staff officer, someone who could anticipate his needs as a commander, keep track and cover the fine details, and basically turn the unit into a well-oiled machine and keep it that way. It was the staff that could either make or break a unit. The 8th TFW was broken, but Olds knew just the man to help him fix it. He called his old friend Chappie James, who joined him at Ubon as director of operations, then later as vice commander of the wing. Building renown as the team of "Blackman and Robin," Chappie and Olds patiently began to turn the hard-luck unit into the most aggressive fighter outfit in Southeast Asia, the famed "Wolfpack" as the 8th TFW is known to this day. Allowing imaginative young leaders to take point in collecting intelligence and planning operations, they created an environment that led to one of the most one-sided air battles in history during Operation Bolo, where the much-feared MiG-21 force of the North Vietnamese air force was decimated by the 8th TFW with the loss of seven MiGs and withdrawal of the Communist 921st Fighter Regiment from combat operations for a number of months as they regrouped and rebuilt. By the end of 1967, Chappie had been reassigned to a stateside command but his honored place in aviation had been assured.
Chappie continued moving up into higher staff positions, becoming vice commander of Military Airlift Command in 1974 and, after earning his fourth star and the rank of General, he became the commanding general of North American Air Defense Command (NORAD), in charge of both United States and Canadian air and space defense forces. During his tenure, he flew a resplendent F-106B interceptor as his personal aircraft.
General Chappie James is remembered as an eloquent public speaker with a tireless dedication to his local communities, an outstanding leader of men, and above all an American patriot.
Born in 1920, James began studies at the Tuskegee Institute, completing civilian flight training along with earning his Bachelor's degree in 1942. Remaining at Tuskegee as a flight instructor, Chappie joined the Aviation Cadet program of what was then the Army Air Forces and received his commission in 1943. While the famed "Red Tails" of the 99th Fighter Squadron went to war under the command of Benjamin O. Davis, Chappie James remained stateside. His turn at combat would come in Korea after the Communist armies of dictator Kim Il-sung invaded South Korea to "unify" the peninsula under Communist rule. As a flight leader in the 12th Fighter-Bomber Squadron of the 18th Fighter-Bomber Wing, Chappie flew 101 combat missions in piston-engine F-51 Mustang and, after unit conversion, jet-powered F-80 Shooting Star fighters. As there was negligible air opposition, most of his missions were hazardous close air support sorties flown in defense of United Nations troops.
In July 1951, Chappie was rotated stateside and assigned to fly all-weather interceptors with the 58th Fighter-Interceptor Squadron. This would mark the beginning of a long personal association with air defense. Chappie soon worked his was up to become the squadron operations officer. By 1953, Chappie had moved up the ladder to take his first command as squadron commander of the 437th Fighter-Interceptor Squadron assigned an all-weather interceptor mission under Air Defense Command. One of the pilots that I interviewed for my book, Harry Schmidt, was assigned to his squadron as a young USAF captain. He has nothing but good things to say about his former commander, and feels that he was an excellent pilot and a fair and able leader. After another command billet as CO of the 60th Fighter-Interceptor Squadron, Chappie was selected to attend the Air Command and Staff College, the first step toward advanced rank. After graduating in the summer of 1957, Chappie was assigned to a staff position in the Air defense Division at the Pentagon.
During Chappie's time at the Pentagon, the sole F-101 wing in Tactical Air Command, the 27th Tactical Fighter Wing, was given orders to deploy its men and aircraft to stand nuclear alert with the 81st Tactical Fighter Wing based in England, replacing their obsolescent F-84F Thunderstreak fighter-bombers. A staff of officers containing among some of the Air Force's best fighter tacticians was led by their legendary operations officer, Lt. Col. William D. "Dinghy" Dunham, who as an officer assigned to Strategic Air Command in the late 1940s wrote the original letter detailing what would later become the F-101 Voodoo. Chappie James joined this select group in the summer of 1960, initially as assistant director of operations to Lt. Col. Dunham. When Dunham left to assume command of the 479th Tactical Fighter Wing, equipped with the hot new Lockheed F-104C Starfighter, Chappie assumed his responsibilities as the wing director of operations for the 81st TFW. The F-101 had been introduced to Europe in 1959, over the strong objections of the commanding general of United States Air Forces Europe (USAFE), who wanted all of his tactical fighter-bomber units to be equipped with the new F-100D. Dunham and his squadron commanders worked hard to adapt their blistering-fast mounts into NATO's first effective all-weather strike aircraft.
Having learned at the feet of the master and now as director of operations, it was Chappie's job to develop concepts of operation and specific plans to attack Soviet and Soviet-bloc targets with fighter-borne nuclear weapons. Although very similar to the F-100D in low-level performance, the radar-equipped F-101A and F-101C fighters assigned to the 81st TFW could run in on their targets at 500 feet and below, even in adverse weather and had a 200-nautical-mile range advantage over the F-100. Based on the far eastern coast of Suffolk, England at the "Twin Bases" of RAF Bentwaters and RAF Woodbridge, the Voodoos were within striking distance of the heart of Soviet air defenses guarding the approaches to Moscow. Chappie constantly reviewed and adjusted plans to attack these vital targets in the Baltic States of Lithuania, Latvia, and Estonia as well as the Leningrad District in European Russia. In the event of a general war with the Soviet Union, Chappie carried the responsibility of ensuring that the Voodoos of the 81st TFW could successfully "kick in the doors" and allow the heavy bombers of Strategic Air Command to pour through the breach and into their targets in the Soviet heartland. Considered by many to be the best unit in the USAF, Chappie's job was to make sure that the point of NATO's spear remained razor sharp.
It was during his tenure with the 81st TFW that Chappie would make a life-changing acquaintance when Col. Robin Olds, World War 2 double-ace and considered a maverick within the Air Force, assumed command of the 81st TFW. Olds was considered by many to be a throwback, a fierce and fun-loving warrior-leader within an increasingly technocratic Air Force culture. Chappie had already established a reputation as an excellent staff officer but also recognized a fellow natural leader in Olds, and the two formed a fast friendship. Chappie was soon promoted to squadron commander of the wing's 92nd TFS and then to deputy commander of operations. Together, he and Olds worked together to burnish the reputation and esprit-de-corps of the 81st TFW to even greater heights. In 1964, Chappie was assigned to the same position in a prestigious slot with the 4453rd Combat Crew Training Wing, which was the USAF unit that introduced the new F-4 Phantom to waiting fighter crews. It was during this time that Olds had pushed things a little too far with USAFE leadership--by his own design. Knowing that he was in line for promotion to brigadier general and wanting to lose an opportunity for a combat command in Vietnam, he had trained a demonstration team composed of the best of his pilots to fly daring Thunderbirds-style in the notoriously touchy and unforgiving Voodoo. Narrowly avoiding a court martial, Olds was sent stateside to cool off while he maneuvered for an opportunity to once again lead young fighter pilots in combat.
Within six months of his dressing down by USAFE commanding general Disosway, Olds had taken command of the hard-luck 8th Tactical Fighter Wing at Ubon airbase in Thailand. Overall morale was low within the unit, but among the staff and squadron commanders there were many individuals who held considerable promise. Olds was not only aggressive and decisive, but also an astute judge of character. While he was the quintessential combat-leader, he recognized that what really made any unit tick and function properly was a good staff officer, someone who could anticipate his needs as a commander, keep track and cover the fine details, and basically turn the unit into a well-oiled machine and keep it that way. It was the staff that could either make or break a unit. The 8th TFW was broken, but Olds knew just the man to help him fix it. He called his old friend Chappie James, who joined him at Ubon as director of operations, then later as vice commander of the wing. Building renown as the team of "Blackman and Robin," Chappie and Olds patiently began to turn the hard-luck unit into the most aggressive fighter outfit in Southeast Asia, the famed "Wolfpack" as the 8th TFW is known to this day. Allowing imaginative young leaders to take point in collecting intelligence and planning operations, they created an environment that led to one of the most one-sided air battles in history during Operation Bolo, where the much-feared MiG-21 force of the North Vietnamese air force was decimated by the 8th TFW with the loss of seven MiGs and withdrawal of the Communist 921st Fighter Regiment from combat operations for a number of months as they regrouped and rebuilt. By the end of 1967, Chappie had been reassigned to a stateside command but his honored place in aviation had been assured.
Chappie continued moving up into higher staff positions, becoming vice commander of Military Airlift Command in 1974 and, after earning his fourth star and the rank of General, he became the commanding general of North American Air Defense Command (NORAD), in charge of both United States and Canadian air and space defense forces. During his tenure, he flew a resplendent F-106B interceptor as his personal aircraft.
General Chappie James is remembered as an eloquent public speaker with a tireless dedication to his local communities, an outstanding leader of men, and above all an American patriot.
Tuesday, February 10, 2015
Something extra: Upgrading the F-101B fire control system
Although the book has yet to be widely released, I have continued adding to and editing the manuscript. In recent months, I have dug up more information on the F-101B and modification of its Hughes MG-13 fire control system to counter Soviet developments in electronic countermeasures (ECM) capability to defeat the ability of attacking interceptors to target their weapons on the intruding bomber. I have a little bit of fact checking to do, so this should be considered provisional at this point but here is what I have. Enjoy!
Bold Journey: The Interceptor Improvement
Program
On 1 November 1961, NORAD
sent to ADC a new NORAD Qualitative Requirement (NQR) for a Long Range Airborne
Passive Homing (LRAPH) system for implementation. The intent was to provide ADC
interceptors with the ability to directly locate and kill Soviet jamming
aircraft by providing a broadband receiver, antenna, and display equipment to
provide relative azimuth and height to the target. The LRAPH system would also help address the
problem of intercepting low-altitude targets as identified a year previously
during the first Sky Shield exercise. A similar system was being considered for
the Bomarc B surface-to-air missile. Air Force Systems Command was directed by
the Pentagon on 26 April 1962 to begin prototype development of an LRAPH system
for all ADC Century-series interceptors: The F-101B, F-102A and F-106A under
$475,000 of FY 1962 QRC funding. Implementation of the LRAPH system was to take
place in two phases, beginning in January 1963.
The first phase, programmed to take one year to complete, would consist
of a redesigned “silent lobing” radar antenna, anti-chaff circuit modifications
to the fire control system, and the addition of an infra-red search and track
system, or IRST. The second phase would
start about a year later and would add parametric amplifiers and rapid
pulse-to-pulse shifting of radar frequency to defeat Soviet sweep jamming
systems. The overall effort would soon
become known as the Interceptor Improvement Program. For the F-101B, the LRAPH system modification
was undertaken as Project “Bold Journey.” This final major
upgrade to the F-101B weapon system took place beginning in February
1963, but it was to provide a tremendous leap in its operational
capability. Under Project Bold Journey, the Interceptor Improvement
Program (IIP) centered on modifications to the Hughes MG-13 to improve the
radar’s ability to function successfully in the face of enemy electronic
countermeasures and offer improved search and tracking capabilities against
low-flying targets. The modification
program coincided with the availability of the new and vastly improved GAR-2B Falcon missile, renamed the AIM-4D as it entered production in February 1963.
The most visible modification associated with the
Interceptor Improvement Program was the installation of a Hughes infrared
search and track (IRST) system in the forward fuselage, replacing the
seldom-used refueling probe. Infrared sensor technology had first been developed by
Germany during World War 2 and saw limited use in detecting Allied night bomber
formations and cueing searchlights against them to permit engagement with
anti-aircraft guns. In the late 1940s
Hughes had begun to adapt the technology for use in a proposed stellar-inertial
navigation system for the Northrop SM-62 Snark intercontinental cruise missile. By the late 1950s, as
a spin-off of the now-cancelled LRI which had resulted in the North American F-108 Rapier, Hughes had developed a new infrared
sensor as a component of the extremely advanced AN/ASG-18 fire control system
beginning in the spring of 1958. As
developed for the F-108, the initial design provided
a field of view of 70 x 140-degrees and an angular resolution of 1 degree. The prototype Hughes system was designated
the X-2, followed by mid-1959 with the X-3.
The Hughes IRST initially operated in 2.5 micron range, using an uncooled lead sulfide (PbS) seeker. As tested in late 1958 through early 1959,
the infrared system was to be capable of detecting a tail-aspect B-47 target from 34.8 nautical miles at 45,000 feet
and 10.3 nautical miles from directly ahead.
A Mach 3 bomber or cruise missile could be detected at 76.5 n. m. from
any aspect due to aerodynamic heating of the wing leading edges and other
structures. By the beginning of 1959,
the system had been described as consisting of a 7-inch diameter silicon
“irdome” and a multi-element telescopic lens composed of silicon and sapphire
elements, features consistent with the use of a very advanced and sensitive
lead selenide (PbSe) array to detect infrared radiation at a range of
wavelengths between 3 to 6 microns. The
unit mounted on the F-101B is also 7 inches in diameter. The IRST used liquid nitrogen to cool the
seeker to increase its sensitivity and the unit could be slaved to the radar
antenna. Although the F-108 had been cancelled by the summer of 1959, evaluation
of the Hughes ASG-18 fire control system continued, using B-58A 55-0665 as a test bed. The modification included the installation of
two IRST units, identical in appearance to the unit later mounted on the F-101B, on either side of the
elongated nose housing the huge new radar.
Modification of the B-58 was completed 2 August 1959 with flight tests
conducted from early 1960 through February 1964.
The Hughes IRST was added to the Voodoo under T.C.T.O.
1F-101B-945 as the first phase of the Interceptor Improvement Program. In the Century-series interceptors, the IR
seeker heads of infrared-guided Falcon missiles could be cued to the target by
the IRST, permitting launch and destruction of the target even in the face of
intense jamming. Work began at Ogden Air Materiel Area with two prototype
aircraft of 4 February 1963. All 339
F-101B and F-101F aircraft assigned to the 16 squadrons assigned
to Air Defense Command received the upgrade, completed at Hill AFB with the
last aircraft completed on 11 December 1964. By the end of December Phase I of the ECCM
upgrades for the Interceptor Improvement Program for all Century-series
interceptors had been completed with the provision of silent lobing radar
antennas, anti-chaff circuitry, and the addition of Hughes IRST systems.
The second phase of modifications under the Interceptor
Improvement Program was covered under T.C.T.O. 1F-101B-944. This second phase included the installation
of a hydraulically tunable magnetron, which allowed rapid changes in the waveform
of the radar signal and made the MG-13 much less susceptible to both conventional “noise” jamming and more advanced “sweep” jammers that had begun to enter
service with Soviet Tu-16P “Badger-J” ECM aircraft in 1962. Sweep jamming worked by working across a
range of frequencies, transmitting at full power to combine the advantages of
both spot and barrage jammers. Success
of sweep jammers depended upon performing tuning changes rapidly to keep the
enemy radar jammed while preventing reacquisition of the target as the jamming
transmitter swept to another frequency. The key for new Soviet systems such as the
“Buket” used on the Tu-16P was the use of a “carcinotron” tube that could
manipulate the outgoing signal much faster than the 2-3 minutes it took for a
operator to do the same manually with the older SPS-1 spot jamming systems that
had to that point been standard equipment on Tu-16 and Tu-95 bombers. In the case of the “Buket” system, the
aircraft carried several automatic transmitters that could simultaneously jam
over a wide range of frequencies. The
same basic equipment was under development for an ECM version of the new,
supersonic Tu-22 medium bomber that had begun low-rate production in 1960. It was reasonable to assume that it would
only be a matter of time until the similar equipment would be retrofitted to the “Bear.” By using the new hydraulically tunable
magnetron, the interceptor’s radar could play the same game against the jamming
bomber by working within a relatively broad frequency range, but change its
specific transmitting frequency much more rapidly than the bomber’s ECM
equipment and defeat its ability to adjust to the fire control radar and
successfully jam it. Therefore, the
hydraulically tunable magnetron gave the upgraded MG-13 tremendously improved
ECCM capability.
The upgraded MG-13 also had an
anti-chaff setting, the counter anti-deception jamming or CADJ mode, that would introduce a bias toward the leading
edge of a chaff cloud, closer to the actual target, rather than the radar
center or “centroid” of the chaff cloud, permitting easier reacquisition and
tracking of the targeted aircraft. Another feature that greatly improved ECCM
ability was to incorporate a lobe-on-receive-only (LORO) modification that
greatly increased the resistance of the MG-13 weapons control system to
deception jamming. In common with the
E-series radars, the MG-13 used conical scan while tracking a target to refine
its angular position. Unfortunately, as deception jamming became increasingly
sophisticated, conical scan radars had proved relatively easy to defeat,
especially with the use of Inverse Gain deception jamming which depended upon
the knowledge of the rotation rate of the nutating radar beam. Adding a LORO feature meant that rotation rate
could not be measured during transmission, so the conical scan rate while the
antenna was receiving could not be known. However, the
upgraded radar was not as effective against the newer and more
sophisticated deception jammers beginning to enter service in the early
1960s. A deception jammer, or “track
breaker” in USAF parlance of the time, worked by gradually introducing a false
return signal, “stealing” the range gate or window when accurate signals were
expected to return, and then introducing false range and bearing information
based on the strength and timing of the spurious return signal. During practice intercepts, the AN/ALQ-16
unit installed in the Convair B-58A often proved adept at defeating the “Home-On-Jamming”
mode of the Voodoo. Project Bold
Journey continued through 1966, with
339 aircraft undergoing modification. By December 1966 this final phase of ECCM improvements to the F-101B,
F-102A, and F-106A had been completed for the Interceptor Improvement Program
with the provision of rapid tuning radars and parametric amplifiers for their
radar fire control systems. The late-production Block 115 and Block 120
aircraft supplied to the Royal Canadian Air Force under Queen’s Row were not modified under the
Interceptor Improvement Program.
As modified under Project Bold
Journey, the upgraded Hughes MG-13 IIP radar operated in I-band in a frequency
agile mode between 8500 MHz and 9250 MHz. The pulse repetition frequency (PRF)
was 910 Hz for a 0.5 microsecond pulse width, for a range displays of 6, 20,
and 40 nautical miles in SP (short pulse) mode and 416 Hz for a 1.0 microsecond
pulse width to allow a range of up to 200 miles in LP (long pulse) mode, with
40, 80, and 200 nautical mile range scales. The radar operated in a pulse
repetition jitter mode with 70 microseconds jitter and used LORO processing for
angle tracking, able to operate at four separate LORO frequencies of 89 Hz, 122
Hz, 145 Hz, and 185 Hz. At peak power,
the MG-13 IIP unit transmitted at 250 kilowatts and as with the original unit
and earlier Hughes radars used an RK6249 magnetron tube. The
normal scope display for the radar intercept officer (RIO) was a B-scope,
displaying range on the y-axis and azimuth on the x-axis. The antenna could be
steered with a joystick on the RIO’s right instrument panel, moving the stick
side-to-side to move the antenna in azimuth and using a thumbwheel on the
inboard side at the top of the stick to adjust elevation. With the “Action” switch depressed, the range
gate marker was adjusted and placed over the target blip by fore-aft movement
of the stick. Once centered on the blip with the range marker lined up, release
of the action switch enabled the MG-13 unit to automatically track the target. A-scope
display could also be selected to plot receiver signal amplitude on a
horizontal range trace. Although the A-scope did not display azimuth, the
antenna could be steered to find the highest amplitude signal. The A-scope display was useful, however, in
finding and identifying the true target contact in the midst of jamming. The 25-inch diameter parabolic antenna could
be set to automatically scan in 4 bar, 2 bar, and 1 bar modes to the center or
to either side of the flight path, along with a boresight mode. The antenna limits for elevation were 35
degrees up and 15 degrees down.
The new sensor capabilities of the F-101B were paired with a new version of the Falcon
missile, the AIM-4D. Developed as the GAR-2B by mating the infrared seeker head from the
F-106’s
GAR-4A missile to the body of the GAR-2A,
the new weapon was far more sensitive, less vulnerable to glare or
countermeasures, and for the first time in an infrared-homing missile offered
at least a theoretical all-aspect capability in both pursuit and lead collision
modes. The AIM-4D was distinguished by a white moisture-proof
sleeve covering the forward half of the missile making it much more reliable
than the earlier GAR-2A. The missile armed after motor burnout at 1.4
seconds after launch. Operating in the
3.8 to 5.4 micron range, the improved IR seeker was sensitive to temperatures
ranging from about 200 to 750 degrees Centigrade, able to home on to relatively
cooler aircraft engines and exhausts than the earlier GAR-2A. The seeker had a field-of-view of 6.5 degrees
and a gimbal limit of 48 degrees. The
AIM-4D seeker could be slaved to either the fire
control radar or the IRST system. Compared
to the GAR-2A, the AIM-4D had a much shorter minimum range, as low as
2,000 feet, a similar engagement envelope out to 90 degrees target aspect
angle, and the ability for forward hemisphere engagement. Just forward of 90 degrees abeam of the
target, maximum engagement range ranged from 17,000 feet to 10,000 feet from
directly head-on to the target. The
Falcon was now no longer a strictly “tail-chase” weapon and gave the Voodoo a
front hemisphere engagement option besides the Genie rocket, now carrying the
new designation AIR-2. The AIM-4D entered service in July 1963 with both the
F-101B and F-102A, quickly replacing the older
GAR-2A (now AIM-4C)
in United States Air Force service while the unmodified Canadian aircraft
continued with the GAR-2A.
During the mid-1960s timeframe of Project Bold Journey, the F-102A was undergoing similar upgrades in sensors and
missiles while a retractable IRST was coupled with the more advanced weapons of
the F-106 to provide the same tactical advantages for
American interceptors. The Hughes IRST
was reportedly sensitive enough to detect a Soviet Tu-95 “Bear” bomber from the front hemisphere due to
the massive heat signature produced by its NK-12 turboprop engines and it was
not unusual to detect targets on the IRST before achieving a lock with the
radar. Although the IRST in F-101B maintenance manuals is referred to generically
as the “IR Receiver and Closed Cycle Cooling System”, the same basic system is
referred to as the “90-C IR-search-track set” for the F-102A and the AN/AAS-15 for the Vought F8U-2NE Crusader serving with the U.S. Navy. The downside of the Hughes IRST was that, at
least for its first year of service, it was not at all reliable and spare
components were in very short supply, often forcing squadron-level maintainers
to use field-expedient solutions to keep the systems functioning.
Museum Day 2015: Part 1
This past Saturday, February 7th, was International Museum Day. We at the Aerospace Museum of California expected that the heavy rains the previous day would continue. Having a previous commitment for the morning, I arrived to sunshine and a dry Voodoo a bit before 1 PM.
My major goal for the day had been to set up a book table with the few advance copies of the new book that I had available and try to gather some numbers to guide me in purchasing books to support a book tour. However, I also had some cleaned and refurbished instruments to reinstall in the rear cockpit, which meant that we had to open the cockpit first--no small task, even with the aid of a forklift. The weather was good, and I decided to leave it open for visitors. It wasn't until an hour before closing that I had everything set up but by then, there had been a steady trickle of visitors who had braved the anticipated rain to come out and visit us. I could concentrate on selling books or greet my guests and talk up my old bird--the choice is a no-brainer so I stood available by my plane and answered questions! As always, we on the Restoration side had a wonderful time and loved the opportunity to show off our collection.
One young lady came up and asked if "Chappie" had flown the Voodoo. I have to admit to a very serious brain fart at that point. Of course, I was familiar with Daniel "Chappie" James: Tuskegee Airman, F-94 pilot and commander of the 437th Fighter-Interceptor Squadron, and part of aviation legend with Robin Olds as "Blackman and Robin" with the 8th TFW "Wolfpack" in Vietnam, and finally commanding general of North American Air Defense Command where his personal aircraft was a two-seat F-106B. However, I had completely forgotten about where Col. Olds first met him: with the 81st TFW, flying F-101A and F-101C fighters out of Suffolk, England. I will tell his story in my next post. Stay tuned!
This is the left side of the nose avionics bay of my bird, 57-0427, showing the heart of the Hughes MG-13 fire control system of the F-101B. Note the two cylinders on the left of the frame. The smaller, upper cylinder contains the receiver for the radar system, while the larger, lower cylinder contains a fairly substantial magnetron used to produce the radar signal pulse. Vacuum-tube magnetrons are still used in microwave ovens and produce the electromagnetic radiation used to heat up your Hot Pockets or frozen burritos (transmitting in E-band, for those interested!) Open the door of your microwave oven to see how many watts your own personal magnetron produces, it should be somewhere around 1000 Watts or 1 kilowatt (kW). This bad boy produced 250 kW per pulse. You didn't want to stand anywhere in front of it while it was being tested.... Operating in the I-band, the pulse generated by the SFD-304 magnetron tube gave the MG-13 a maximum search range of 200 miles and a tracking range of up to 40 miles. Even for 1959, it was old technology but it was proven, able to be upgraded through the course of the early 1960s, and compared to its contemporaries pretty reliable--just what was needed for a long-range all-weather interceptor.
Photo Credit: Ronald Easley
My major goal for the day had been to set up a book table with the few advance copies of the new book that I had available and try to gather some numbers to guide me in purchasing books to support a book tour. However, I also had some cleaned and refurbished instruments to reinstall in the rear cockpit, which meant that we had to open the cockpit first--no small task, even with the aid of a forklift. The weather was good, and I decided to leave it open for visitors. It wasn't until an hour before closing that I had everything set up but by then, there had been a steady trickle of visitors who had braved the anticipated rain to come out and visit us. I could concentrate on selling books or greet my guests and talk up my old bird--the choice is a no-brainer so I stood available by my plane and answered questions! As always, we on the Restoration side had a wonderful time and loved the opportunity to show off our collection.
One young lady came up and asked if "Chappie" had flown the Voodoo. I have to admit to a very serious brain fart at that point. Of course, I was familiar with Daniel "Chappie" James: Tuskegee Airman, F-94 pilot and commander of the 437th Fighter-Interceptor Squadron, and part of aviation legend with Robin Olds as "Blackman and Robin" with the 8th TFW "Wolfpack" in Vietnam, and finally commanding general of North American Air Defense Command where his personal aircraft was a two-seat F-106B. However, I had completely forgotten about where Col. Olds first met him: with the 81st TFW, flying F-101A and F-101C fighters out of Suffolk, England. I will tell his story in my next post. Stay tuned!
This is the left side of the nose avionics bay of my bird, 57-0427, showing the heart of the Hughes MG-13 fire control system of the F-101B. Note the two cylinders on the left of the frame. The smaller, upper cylinder contains the receiver for the radar system, while the larger, lower cylinder contains a fairly substantial magnetron used to produce the radar signal pulse. Vacuum-tube magnetrons are still used in microwave ovens and produce the electromagnetic radiation used to heat up your Hot Pockets or frozen burritos (transmitting in E-band, for those interested!) Open the door of your microwave oven to see how many watts your own personal magnetron produces, it should be somewhere around 1000 Watts or 1 kilowatt (kW). This bad boy produced 250 kW per pulse. You didn't want to stand anywhere in front of it while it was being tested.... Operating in the I-band, the pulse generated by the SFD-304 magnetron tube gave the MG-13 a maximum search range of 200 miles and a tracking range of up to 40 miles. Even for 1959, it was old technology but it was proven, able to be upgraded through the course of the early 1960s, and compared to its contemporaries pretty reliable--just what was needed for a long-range all-weather interceptor.
Photo Credit: Ronald Easley
Monday, February 9, 2015
This Day in McDonnell Voodoo History: February 9th
In
1956, the USAF approved a “standard” afterburner for the F-101B in place of the
original “short” afterburner. The short
afterburners were needed to allow room to rotate the nose for takeoff and landing,
but with the longer tail and extended landing gear of the F-101 it could safely
accommodate a larger engine. The
afterburner nozzle of the J57-P-23 engine of the F-102 was mounted to the J57-P-13
engine to yield the J57-P-53. Due to
increased mixing of fuel and residual oxygen in the longer tail pipe, the
J57-P-53 saw a 1,000-pound increase in thrust.
More advanced designs with convergent-divergent nozzles, such as the
J57-P-35 promising 17,200 pounds, were being evaluated.
The original production engine for the F-101B, the Pratt & Whitney J57-P-53. The afterburner nozzle was borrowed from the engine for its Convair F-102A stable mate, the J57-P-23. Hot exhaust gases exiting the combustion chamber of the engine and afterburner (detailed in the lower photo) would converge toward a minimum diameter at the nozzle exit to produce a maximum amount of thrust without exceeding the temperature limits of the structure. Thrust is the product of mass x velocity, but with the traditional convergent exhaust nozzle design, uncontrolled expansion of the exhaust gases after exiting the nozzle led to the formation of a normal shock wave at the nozzle exit, limiting its velocity to Mach 1.0. If a means could be found to increase the exhaust velocity, thrust of the basic engine could be significantly increased. Many engine manufacturers, including Pratt & Whitney, expended great effort towards that goal. Success was achieved, but the learning curve needed to get there proved to be extremely steep.
While most manufacturers concentrated on very sophisticated variable-area convergent-divergent exhaust nozzles, Pratt & Whitney finally settled on a relatively heavy design that was mechanically simple and proved very reliable. This was incorporated into the definitive J57-P-55 engine that equipped the 16th aircraft on. The basic nozzle design was also carried over to US Navy Vought F8U-2 Crusader aircraft in the form of the J57-P-16, J57-P-20, and J57-P-420 engines. In its ultimate form as the J57-P-420, the J57 produced a maximum afterburning thrust of 19,600 pounds in upgraded F-8H and F-8J Crusader fighter-bombers.
Photo credit: USAF
The original production engine for the F-101B, the Pratt & Whitney J57-P-53. The afterburner nozzle was borrowed from the engine for its Convair F-102A stable mate, the J57-P-23. Hot exhaust gases exiting the combustion chamber of the engine and afterburner (detailed in the lower photo) would converge toward a minimum diameter at the nozzle exit to produce a maximum amount of thrust without exceeding the temperature limits of the structure. Thrust is the product of mass x velocity, but with the traditional convergent exhaust nozzle design, uncontrolled expansion of the exhaust gases after exiting the nozzle led to the formation of a normal shock wave at the nozzle exit, limiting its velocity to Mach 1.0. If a means could be found to increase the exhaust velocity, thrust of the basic engine could be significantly increased. Many engine manufacturers, including Pratt & Whitney, expended great effort towards that goal. Success was achieved, but the learning curve needed to get there proved to be extremely steep.
While most manufacturers concentrated on very sophisticated variable-area convergent-divergent exhaust nozzles, Pratt & Whitney finally settled on a relatively heavy design that was mechanically simple and proved very reliable. This was incorporated into the definitive J57-P-55 engine that equipped the 16th aircraft on. The basic nozzle design was also carried over to US Navy Vought F8U-2 Crusader aircraft in the form of the J57-P-16, J57-P-20, and J57-P-420 engines. In its ultimate form as the J57-P-420, the J57 produced a maximum afterburning thrust of 19,600 pounds in upgraded F-8H and F-8J Crusader fighter-bombers.
Photo credit: USAF
Sunday, February 8, 2015
This Day in McDonnell Voodoo History: February 8th
In 1963, McDonnell released its final model for
the VooDoo, a modification to the
RF-101 as the Model 36DH. Sharing
equipment with the new McDonnell RF-4C, the equipment would be incorporated
into the fleet under “Project 1181.” The
KA-2 cameras were replaced with new KS-72 cameras along with a new control
system, while the KA-1 cameras were retained.
A compact KA-56 panoramic camera provided horizon-to-horizon coverage. After the miserable experience over Cuba in
1962, the Project 1181 modification gave the old RF-101C new and highly-demanded
capabilities.
On the same day in 1967, Capt. John Rogers was hit by anti-aircraft artillery over a coastal objective in North Vietnam and ejected just offshore. Racing against enemy junks and sampans, US Navy A-1 Skyraiders arrived to cover his rescue by the destroyer USS Cunningham.
In this photo, the small undernose fairing for the KA-56 panoramic camera is clearly visible in this early production RF-101C, 56-0168, modified with new camera equipment under Project 1181. The small-format KS-72 cameras replaced the older 9" x 9" format KA-2 cameras in the nose stations and the films produced were very unpopular with photo interpreters. However, they did not suffer the same reliability and image quality problems experienced at high speed and very low level as the older KA-2 equipment had during the Cuban Missile Crisis in October, 1962. Provision of the KA-56 to provide horizon-to-horizon photo coverage along with the smaller KS-72 cameras also allowed them to be used in a split vertical configuration to complement the long focal-length KA-1 cameras that were retained behind the cockpit. Project 1181 not only allowed increased survivability for the RF-101C and its crews by permitting reliable camera operation at very low altitudes, but greatly increased its versatility as an intelligence collection platform.
Photo Credit: NMUSAF via Mark Nankivil
On the same day in 1967, Capt. John Rogers was hit by anti-aircraft artillery over a coastal objective in North Vietnam and ejected just offshore. Racing against enemy junks and sampans, US Navy A-1 Skyraiders arrived to cover his rescue by the destroyer USS Cunningham.
In this photo, the small undernose fairing for the KA-56 panoramic camera is clearly visible in this early production RF-101C, 56-0168, modified with new camera equipment under Project 1181. The small-format KS-72 cameras replaced the older 9" x 9" format KA-2 cameras in the nose stations and the films produced were very unpopular with photo interpreters. However, they did not suffer the same reliability and image quality problems experienced at high speed and very low level as the older KA-2 equipment had during the Cuban Missile Crisis in October, 1962. Provision of the KA-56 to provide horizon-to-horizon photo coverage along with the smaller KS-72 cameras also allowed them to be used in a split vertical configuration to complement the long focal-length KA-1 cameras that were retained behind the cockpit. Project 1181 not only allowed increased survivability for the RF-101C and its crews by permitting reliable camera operation at very low altitudes, but greatly increased its versatility as an intelligence collection platform.
Photo Credit: NMUSAF via Mark Nankivil
This Day in McDonnell Voodoo History: February 6th
In 1951, the USAF discussed the “ultimate”
version of the new SAC escort fighter, defining performance needed to match the
speed, range, and altitude newer jet bombers such as the Boeing B-47B. It would have to be able to cruise at 560 mph
over a radius of 1,500 miles and be able to exceed the performance of Soviet
interceptors capable of over 900 mph and 60,000 feet, anticipated by 1956. The AN/APG-37 radar originally developed for
the F-86D interceptor was considered for the new design. In March 1951, an improved VooDoo, the Model 36F with Westinghouse
J46 engines, would be selected.
Photo: Characteristics Summary of the proposed Model 96F.
Photo credit: USAF via Ryan Crerie
Photo: Characteristics Summary of the proposed Model 96F.
Photo credit: USAF via Ryan Crerie
Thursday, February 5, 2015
This Day in McDonnell Voodoo History: February 5th
In 1958, the VooDoo
fleet experienced the first of several groundings due to leaks in the fuel
and hydraulic systems, leading to a number of catastrophic failures, collapsed
landing gear, and in-flight fires. In
this instance, the F-101 was grounded for inspection and repair of “Marman
clamps” connecting fuel lines to the main tanks. One of the founders of the Marman Corporation
in the mid-1940s was engineer Herbert M. Marx, known to millions as the
“fourth” of the famous Marx Brothers, “Zeppo” Marx, who usually played both the
straight man and romantic lead in many of their films. After leaving the silver screen behind to pursue a career as an engineer, he became a successful inventor and his Marman Clamps are still widely used to this day.
Wednesday, February 4, 2015
This Day in McDonnell Voodoo History: February 4th
In 1963, a major mid-life upgrade of the F-101B
began under Project Bold Journey. In the first phase, an advanced infrared
system was installed, replacing the refueling probe in the nose. The addition of the new IRST allowed the
F-101B to detect the heat signatures of approaching bombers and cruise missiles,
allowing targeting of improved AIM-4D Falcon
missiles even in the face of intense jamming. Similar equipment was also retrofitted onto
Convair F-102A and F-106 interceptors.
Hughes Aircraft Company had begun work on infrared sensor systems in the early 1950s while developing a stellar-inertial guidance system for the Northrop SM-62 Snark intercontinental cruise missile. This, in turn, had been based on German research conducted during World War 2. By 1958, Hughes was testing infrared search-and-track systems but due to the inherent limitations of their uncooled lead sulfide detector arrays, they lacked the desired range and were vulnerable to countermeasures such as flares. Since lead sulfide seekers could only detect the relatively short-wavelength infrared radiation produced by hot engine parts, they were limited to rear-quarter use.
Photo credit: USAF
Hughes pioneered research on other compounds and optical elements that would be effective in the 3-6 micron range, where the seeker could detect the heat signature of the relatively cooler exhaust plume and hot wing leading edges and other structures of supersonic targets, significantly increasing detection range regardless of target aspect. For the new Hughes system, the new detector array used lead selenide, coupled with optical elements composed of exotic materials such as sapphire.
Originally developed for the canceled North American F-108 Rapier interceptor, the technology was transferred to existing Century-series interceptors. By 1962, the Soviets were introducing new, upgraded electronic warfare equipment such as the "Buket" system for a dedicated ECM escort version of the Tu-16 Badger medium-range bomber. NORAD exercises against Strategic Air Command bombers also highlighted the vulnerability of its interceptor force to low level penetration as the radar returns of the huge bombers were often lost within the even larger radar return from the ground. The Hughes IRST system allowed the F-101B Voodoo and other interceptors to target bombers, even in the face of intense jamming as well as increasing the probability of detecting low-altitude intruders. In the case of high-speed, high-altitude bomber or cruise missile targets, the sensitivity of the Hughes IRST often allowed a greater detection range than the MG-13 radar system of the F-101B.
IRST technology fell by the wayside as the next generation of fighter-interceptors introduced solid-state radars using traveling wave tubes (TWT) and master oscillator power amplifies (MOPA) to allow the radar to sense the different Doppler shift of low-altitude targets and enable true "look-down, shoot-down" capability. However, advanced developments of this technology are becoming more common to augment advanced radar capabilities and provide effective sensors against stealthy or small, low-signature targets such as missiles. That technology all traces back to the Hughes systems installed in the F-101B and its stable mates in the early 1960s.
Hughes Aircraft Company had begun work on infrared sensor systems in the early 1950s while developing a stellar-inertial guidance system for the Northrop SM-62 Snark intercontinental cruise missile. This, in turn, had been based on German research conducted during World War 2. By 1958, Hughes was testing infrared search-and-track systems but due to the inherent limitations of their uncooled lead sulfide detector arrays, they lacked the desired range and were vulnerable to countermeasures such as flares. Since lead sulfide seekers could only detect the relatively short-wavelength infrared radiation produced by hot engine parts, they were limited to rear-quarter use.
Photo credit: USAF
Hughes pioneered research on other compounds and optical elements that would be effective in the 3-6 micron range, where the seeker could detect the heat signature of the relatively cooler exhaust plume and hot wing leading edges and other structures of supersonic targets, significantly increasing detection range regardless of target aspect. For the new Hughes system, the new detector array used lead selenide, coupled with optical elements composed of exotic materials such as sapphire.
Originally developed for the canceled North American F-108 Rapier interceptor, the technology was transferred to existing Century-series interceptors. By 1962, the Soviets were introducing new, upgraded electronic warfare equipment such as the "Buket" system for a dedicated ECM escort version of the Tu-16 Badger medium-range bomber. NORAD exercises against Strategic Air Command bombers also highlighted the vulnerability of its interceptor force to low level penetration as the radar returns of the huge bombers were often lost within the even larger radar return from the ground. The Hughes IRST system allowed the F-101B Voodoo and other interceptors to target bombers, even in the face of intense jamming as well as increasing the probability of detecting low-altitude intruders. In the case of high-speed, high-altitude bomber or cruise missile targets, the sensitivity of the Hughes IRST often allowed a greater detection range than the MG-13 radar system of the F-101B.
IRST technology fell by the wayside as the next generation of fighter-interceptors introduced solid-state radars using traveling wave tubes (TWT) and master oscillator power amplifies (MOPA) to allow the radar to sense the different Doppler shift of low-altitude targets and enable true "look-down, shoot-down" capability. However, advanced developments of this technology are becoming more common to augment advanced radar capabilities and provide effective sensors against stealthy or small, low-signature targets such as missiles. That technology all traces back to the Hughes systems installed in the F-101B and its stable mates in the early 1960s.
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