Manufactura Aditiva aplicada al diseño y fabricación de armas nucleares

La Manufactura Aditiva (en adelante AM por sus siglas en inglés), frecuentemente denominada como Impresión 3D, permite obtener objetos tridimensionales mediante la adición de capas de materiales a partir de un modelo informático.

Esto contrasta con la manufactura convencional o sustractiva, que permite obtener objetos tridimensionales mediante la sustracción de material, siguiendo -o no, como por ejemplo en el caso de la escultura manual- un modelo informático.

La AM reduce las complejidades de los procesos de producción a programas de software, Impresoras 3D y materiales asociados: metales, termoplásticos, fotopolímeros, y un largo etcétera. Esto ofrece una mayor flexibilidad, reduce el desperdicio en la producción y puede permitir la fabricación de algunos artículos que no es posible obtener mediante la manufactura convencional.

La AM ha avanzado constantemente y, de alguna manera, podría considerarse más una tecnología emergida que emergente. No obstante, hay que tener presente que complementa pero no sustituye a los métodos de fabricación tradicional: A cada producto, su tecnología. Sin embargo, al evaluar los riesgos de proliferación de armas nucleares que pueden venir aparejados a las tecnologías AM, es necesario considerar a quién podría beneficiar esta proliferación, y en qué medida sería posible aplicar la AM para fabricar la bomba y su vehículo de transporte.

Fabricación de una bomba nuclear 

En primer lugar, pensemos en organizaciones terroristas.

¿Es posible que la AM les permita obtener de alguna manera un arma nuclear?

La respuesta es NO, o al menos que no es tan simple: Por un lado, algunos materiales esenciales no están disponibles o no son adecuados para la Impresión 3D. Por otro lado, no es posible producir un arma nuclear de principio a fin conectando un ordenador a una Impresora 3D y presionando el botón de inicio.

En el mejor de los casos, tan sólo algunos componentes de las armas podrían imprimirse. Y aún en ese caso, faltaría conseguir el resto de componentes y saber cómo ensamblarlos. Por tanto, el número de organizaciones terroristas con capacidad de sacar beneficio de la aplicación de la AM a la fabricación de armas nucleares quedaría reducida a grupos que cuenten con el necesario conocimiento, experiencia y capacidades para diseñarlas y producirlas de una manera tan eficiente como secreta.

Considerando lo anterior, existe por tanto un riesgo riesgo extremadamente reducido de que organizaciones terroristas puedan utilizar la tecnología AM para conseguir armas nucleares.

En segundo lugar pensemos en "estados gamberros": En este caso, sí que existe un cierto riesgo de que traten de aprovechar las posibilidades inherentes a la manufactura aditiva para el desarrollo de un arma nuclear, pero sólo en la medida que cuenten con los medios humanos y técnicos para su fabricación posterior.

Fabricación de misiles capaces de portar una bomba nuclear

Hemos visto que fabricar una bomba nuclear utilizando manufactura aditiva no es tan fácil como para prestarle un minuto más.

Ahora bien, ¿Y los misiles? Ahí si que existen posibilidades dignas de considerar: La AM ya se usa ampliamente en cadenas de suministro relacionadas con la fabricación de misiles, y existen al respecto diversos casos de éxito publicados por las compañías Orbital ATK, Raytheon y Relativity Space. 

En definitiva, es posible fabricar componentes de misiles mediante AM, e incluso me atrevería a afirmar que será imperativo en la medida que el misil deba desplazarse a velocidades hipersónicas, ya que tales velocidades requieren piecerío de geometría compleja, imposibles o muy difíciles de obtener mediante la manufactura convencional.

Manufactura Aditiva e hipervelocidad, claves del GBSD

A finales del pasado mes de julio, Boeing anunció su decisión de abandonar la carrera para fabricar la próxima generación de ICBMs que deberá reemplazar a los anticuados Minuteman III. ¿La razón oficial? Muy simple: no podrá desarrollarlo y fabricarlo a un precio competitivo. Es necesario fabricar misiles más rápidos a menor coste, y Boeing ha tirado la toalla. Vamos a ver por qué.

¿Por qué reemplazar los Minuteman III?

El armamento nuclear intercontinental constituye uno de los pilares de la capacidad norteamericana de prevenir un ataque nuclear contra su territorio: A menos que se trate de estados gobernados por suicidas, cabe descartar que una potencia nuclear se arriesgue a llevar a cabo un ataque masivo contra territorio norteamericano, ya que la respuesta sería proporcional. Esto ha sido así durante decenas de años, pero ya no: Los Minuteman III datan de la década de los 70, y hace ya bastantes años que empezaron a mostrar síntomas de no poder asegurar el poder disuasorio que necesita Estados Unidos.

¿Qué reemplazará a los Minuteman III?

Para su reemplazo se ha puesto en marcha un programa dotado con un presupuesto de 85.000 millones de dólares, denominado GBSD. Inicialmente se presentaron propuestas por parte de Boeing, Lockheed Martin y Northrop Grumman, pero Lockheed fue eliminado y Boeing ha dicho que no le compensa. ¿Resultado? Northrop Grumman es ahora la única empresa con posibilidades reales de ganar el contrato.

¿Qué puede ofrecer Northrop Grumman al programa GBSD?

Si hay una palabra clave que se repita cada vez con más frecuencia en el Pentágono, esta es "hipervelocidad": Los adversarios de Estados Unidos han puesto sus ojos en las posibilidades que representa la hipervelocidad, y han desarrollado con aparente éxito ciertos proyectos capaces de amenazar seriamente la tradicional supremacía militar norteamericana. Por tanto, es necesario desarrollar misiles más rápidos que los del enemigo. Y cuando hablamos de hipervelocidad estamos hablando de enfrentarnos a desafíos tecnológicos que exigen en gran medida el uso de tecnologías de Manufactura Aditiva, y es ahí donde Northrop Grumman podría tener su gran oportunidad, ya que es propietaria de Orbital ATK.

¿Quien es Orbital ATK?

Orbital ATK es una compañía líder mundial en tecnología aeroespacial para la industria militar. Cuenta con 12.000 empleados en plantilla, repartidos dentro y fuera de los Estados Unidos. Esta compañía lleva ya muchos años desarrollando motores de cohete para hipervelocidad, y ya en 2016 probó con éxito una cámara de combustión para motores de cohetes hipersónicos, impresa en 3D. Por tanto, estamos hablando de una compañía que cuenta con el conocimiento y experiencia requeridos para aplicar con éxito la Manufactura Aditiva en orden a conseguir fabricar en tiempo y coste el tipo de motores que requiere el GBSD. En tiempo, ya que se trata de una carrera contrarreloj. Y en coste, porque el presupuesto es reducido.

Additive Manufacturing for Hypersonic Missile Warheads

Designing a warhead for high velocities is dramatically different than designing a normal warhead, as it needs to be shaped differently to ensure the fragmentation occurs as intended against the target.

Using decades of experience in developing and fielding advanced warheads, Orbital ATK has designed, built and validated a new missile warhead for hypersonic speeds in less than 60 days.

In words of Pat Nolan -Vice President and General Manager of Missile Products at Orbital ATK- “Successfully completing an R&D program in less than 60 days does not happen by accident. There are very few companies that can offer a similar combination of technical expertise and schedule responsiveness, and our deep heritage in high speed systems as well as warheads, fuzes and rocket motors, enables our team to develop innovative technologies that will ultimately help the warfighter be ready for challenges on the battlefield and able to execute their missions reliably, precisely and safely.”

Orbital ATK is a global leader in aerospace and defense technologies. The company designs, builds and delivers space, defense and aviation systems for customers around the world, both as a prime contractor and merchant supplier.

Its main products include:

• Advanced aerospace structures
• Launch vehicles and related propulsion systems
• Missile products, subsystems and defense electronics
• Precision weapons, armament systems and ammunition
• Satellites and associated space components and services

Headquartered in Dulles, Virginia, Orbital ATK employs approximately 14,000 people across the U.S. and in several international locations. 

Orbital ATK, ready to provide the GBSD program

As designs for the next generation ICBM are being matured, Orbital ATK’s experience has resulted in smart commonality, commercial practices, and shared facilities and workforce.

The company has honed numerous capabilities that can reduce risk and shorten development timelines for GBSD. As an experienced flight system/launch vehicle provider, the company has integrated and launched flight systems at sites around the world, and advanced, common avionics have flown on more than 100 missions with 100 percent success.

Including strategic missile targets and interceptors, Orbital ATK has developed, on average, two new flight systems each year for the past 20 years. In addition, Orbital ATK has significant experience building flight-proven composite structures like shrouds, interstages and motor cases. The company has also developed nuclear hardness and survivability protection for its structures, which will help ensure the success of GBSD.

Orbital ATK has modern, automated facilities ready to support GBSD development and production. The company currently utilizes Additive Manufacturing, virtual reality and model-based systems engineering to design and build state-of-the-art rocket motors. In 2017, Orbital ATK’s solid rocket motors achieved 100-percent success on 16 flights and 11 static fires for a total of 64 motors fired.

Orbital ATK has played a key role on every Intercontinental Ballistic Missile (ICBM) program for more than five decades. Since the Minuteman I was first fielded in 1962, Orbital ATK, along with its legacy companies, has provided motor stages and refurbishment services for the program. Today, Minuteman III continues to play an integral role in our nation’s defense, but is preparing to be replaced by the next generation ICBM program: Ground Based Strategic Deterrent (GBSD).

The Minuteman III weapon system is projected to be in service through 2030, and sustainment activities like those Orbital ATK is now performing on a Propulsion Subsystem Support Contract for the U.S. Air Force Nuclear Weapons Center, Intercontinental Ballistic Missile Systems Directorate at Hill Air Force Base, will ensure operational readiness through that time. Once Minuteman III is retired, the Air Force’s GBSD program will take over: “The Orbital ATK team is dedicated to helping the Air Force with a smooth transition to the GBSD system,” said Charlie Precourt, Vice President and General Manager of Orbital ATK’s Propulsion Systems Division. “Minuteman III sustainment is a vital element of our nation’s defense and the Air Force is partnered with Orbital ATK to ensure that Minuteman remains safe, capable, reliable and responsive while beginning development of GBSD."

With a long history of ICBM experience, proven expertise in flight systems and components, and the ability to share facilities and experienced workforce across programs to keep costs down, Orbital ATK is ready to provide the GBSD program with outstanding solutions throughout its lifecycle.

Additive manufacturing to develop advanced warheads

In words of Richard Truitt -Orbital ATK’s program manager for warhead development programs- “Additive Manufacturing allows us to make complicated geometries, which would benefit a hypersonics application, without the nasty, long schedule,” .

And beyond building warheads rapidly for testing, manufacturing them using 3D Printing capabilities would likely drive down the cost because instead of a machinist starting with a solid chunk of steel or aluminum, which is expensive, and throwing away 99 percent of it, there is no waste. “It’s an enabling technology for us to design and deliver weapons or warheads and get them to the warfighter,” Truitt said.

In what is a major first for the company, Orbital ATK announced the successful test of a partially-3D printed warhead designed for hypersonic weapons. Taking place on March 29, the testing comes just sixty days after conception, with three out of five of the warhead’s major components made using Additive Manufacturing. Speaking to Defense News, Orbital said the test aimed to examine what effects the fragmentation will have on various targets.

Orbital ATK’s efforts are among many initiatives both within U.S. industry and the Defense Department to stay ahead of peer competitors Russia and China, who are both heavily engaged in developing hypersonic weapons. Orbital decided to try Additive Manufacturing on a warhead design for hypersonic applications because the Defense Department is moving full speed ahead with hypersonic technology development in the coming years as it decides how it will employ such weapons.

The company has developed its LEO (Lethality Enhanced Ordnance) warhead capability and some modeling techniques to help look at fragmentation design on certain target sets. In words of Pat Nolan -vice president and general manager of Orbital ATK’s missile products division- “Now we’re coupling our rocket motor hypersonic experience with our warhead design experience to design a warhead that can survive at high speeds, high temperatures, when you’re going that fast,”. The company wants to be ready with the right modeling when hypersonic weapons prototypes and testing begin to ramp up, and the data obtained in the test will be used to measure up against what the engineers believed would happen based on modeling and simulation. The test itself was conducted in a traditional arena where the warhead is hung from above and metal panels surround it in a half circle that are designed to measure how the fragmentation from the warhead disperses upon detonation. High-speed cameras are rigged to measure the velocity of the fragmentation. Another two panels that consist of layers of material -in this case housing insulation- are designed to capture shrapnel in order for the pieces to be measured as well as the depth of perforation.

The 50 lb (22 Kg) warhead went from conception to test in 60 days, according to Truitt. The team began designing the warhead at the start of February, he said, and using Additive Manufacturing to build a large portion of the components cut out at least a month and a half to manufacture the warhead. “If you walk around it, you will see it’s not a cylinder, it’s got some really complicated dimensions. Getting that part in that dimension in a very short time is nearly impossible,” Truitt said. Orbital received the hardware to build the warhead in less than two weeks, he added. “We are really happy to do this test with additive manufactured parts because it is going to tell us, does that actually function the way a normal component would,” Truitt said prior to the test. 

Orbital ATK and AMRDEC: Additive Manufacturing for Rocket Motors

As part of the Army’s Missile Science and Technology Enterprise objectives, Orbital ATK and AMRDEC have developed a prototype of motor built using Additive Manufacturing, to demonstrate and mature new and emerging materials technologies to enhance system effectiveness and achieve insensitive munitions compliance for next generation weapons.

“Orbital ATK has been very successful in taking additive manufacturing out of the academic world and incorporating it into our industrial design and operations,” said Pat Nolan, Vice President and General Manager for Orbital ATK’s Missile Products Division, part of the Defense Systems Group. “Our goal is not just to create industry firsts, but to create practical, reliable solutions that increase our products’ effectiveness while reducing the time it takes to get them into the field.”

The motor was developed in partnership with the AMRDEC (U.S. Army Aviation and Missile Research, Development and Engineering Center) at Redstone Arsenal, Alabama. It incorporates leading-edge materials technologies designed to improve the performance and safety of a next generation anti-tank missile system. The prototype boost motors featured a high strength graphite epoxy composite case, a reduced sensitivity minimum signature rocket propellant, and 3-D printed components. Assembly and testing of the prototype motors was conducted at Orbital ATK’s Tactical Propulsion and Ordnance facility in Rocket Center, WV. The test firings successfully validated boost motor and component performance across the full operational temperature range, closely matching pre-test predictions and meeting all test objectives.