Airbus va développer la constellation d'observation de la Terre CO3D du CNES

Sur le même sujet

• 

  25 juin 2020 | International, Aérospatial

  The F-35 Lightning II can’t fly in lightning once again

  By: Valerie Insinna WASHINGTON — The most widely used variant of the F-35 Joint Strike Fighter is currently unable to fly in thunderstorms after the discovery of damage to one of the systems it uses to protect itself from lightning, its prime contractor Lockheed Martin said Wednesday. To safely fly in conditions where lightning is present, the F-35 relies on its Onboard Inert Gas Generation System, or OBIGGS, which pumps nitrogen-enriched air into the fuel tanks to inert them. Without this system, a jet could explode if struck by lightning. However, damage to one of the tubes that distributes inert gas into the fuel tank was discovered during routine depot maintenance of an F-35A at Hill Air Force Base's Ogden Logistics Complex in Utah, Lockheed said in a statement. Lockheed temporarily paused F-35 deliveries June 2-23 as the company validated whether it was properly installing OBIGGS systems. However, “it appears this anomaly is occurring in the field after aircraft delivery,” Lockheed said in a statement. Lockheed has since delivered two F-35s, company spokesman Brett Ashworth said. Because it cannot be confirmed that the OBIGGS system would function properly if the jet was hit by lightning, the F-35 Joint Program Office has opted to institute flight restrictions. “As a safety precaution, the JPO recommended to unit commanders that they implement a lightning flight restriction for the F-35A, which restricts flying within 25 miles of lightning or thunderstorms,” Lockheed said. “We are working with the F-35 Joint Program Office (JPO) on a root cause corrective action investigation to determine next steps.” The issue only seems to affect the F-35A conventional-takeoff-and-landing variant, which is used by the U.S. Air Force and the majority of international customers. The OBIGGS design is slightly different on the F-35B short-takeoff-and-vertical-landing variant due to the aircraft's lift fan, and the problem has not been observed on F-35C carrier-takeoff-and-landing aircraft, Ashworth said. Bloomberg, which obtained a JPO memo dated June 5, reported that flawed tubes were found in 14 of the 24 “A” models inspected. The JPO did not respond immediately to a request for comment. For a plane nicknamed “Lightning II,” the F-35′s lightning protection systems have, ironically, become an embarrassing problem issue for the jet at times throughout its development. The F-35 was prohibited from flying within 25 miles of lightning in the early 2010s after the Pentagon's weapons tester discovered deficiencies with the original OBIGGs system in getting enough inert gas into the fuel tanks. Those restrictions were rescinded after the OBIGGS was redesigned in 2014. https://www.defensenews.com/air/2020/06/24/the-f-35-lightning-ii-cant-fly-in-lightning-once-again/

• 

  17 juin 2019 | International, Autre défense

  Enabling Revolutionary Nondestructive Inspection Capability

  X-rays and gamma rays have a wide range of applications including scanning suspicious maritime shipping containers for illicit materials, industrial inspection of materials and processes, and medical diagnostic and therapeutic procedures. Current technologies, however, are not ideal. X-rays produce a continuum of energies that limit their inspection and diagnostic performance, and gamma rays can only be produced at specific energies unique to a given radioactive isotope. DARPA today announced its Gamma Ray Inspection Technology (GRIT) program. GRIT seeks novel approaches to achieve high-intensity, tunable, and narrow-bandwidth sources of gamma ray radiation in a compact, transportable form factor that would enable a wide range of national security, industrial, and medical applications. A Proposers Day webinar describing the goals of the program is scheduled for July 8, 2019. “What we're trying to do in GRIT is transform the use of x-rays and gamma rays,” said Mark Wrobel, program manager in DARPA's Defense Sciences Office. “Current sources of gamma rays, like Cobalt-60 or Cesium-137, are not very flexible. They require special licenses to possess and only emit gamma rays at very specific energies. What we desire is a source of very high-energy photons that we can tune to match the application we need. This ranges from more effective detection of illicit cargo, to a more informative medical x-ray.” GRIT aims to provide a source of tunable, pure x-rays and gamma rays from tens of keV (kilo-electron volts) up through over ten MeV (mega-electron volts). Currently, tunable and narrow bandwidth gamma ray sources only exist at highly specialized user facilities best suited for basic research and are not able to support broad practical applications. Shrinking these photon sources to a transportable system is a major goal and challenge of the GRIT program. GRIT technology could make possible a range of new inspection and diagnostic protocols. In medical and industrial radiography, for example, GRIT could enable revealing specific elemental and material content, such as calcium in bones or specific metals in cargo. A typical x-ray only shows differences in density in the object being inspected – whether a piece of luggage at an airport, or an individual at a doctor's office. If successful, a GRIT x-ray source could be tuned to detect and quantify the concentration of specific elements of interest, such as the amount of calcium in a given bone x-ray, enabling radiologists to actually see bone composition. Tuning energy between 10s of keV to over 100 hundred keV would allow detection of specific elements that might be of interest in characterizing novel materials and processes at micron scales. These techniques would be relevant to defense applications including non-destruction inspection of novel additively manufactured materials and alloys for their elemental composition. At energy levels in the MeV range, gamma ray photons have high enough energy to actually interact with the nuclei of atoms. Whereas x-rays work by interacting with the shells of atoms, GRIT would be able to stimulate the nucleus of an atom to bring about an effect called nuclear resonance fluorescence, a sort of “fingerprint” that is unique to each isotope on the periodic table. “With GRIT, you could probe and detect specific isotopes of interest by fine-tuning the photon energy to minimize background noise and take advantage of the nuclear resonance fluorescence phenomenon,” Wrobel said. “Those isotopes could be rare-earth elements of interest or special nuclear materials. To be able to definitively say, ‘Yes, there's highly enriched uranium in this object' and be able to characterize how much is present would be a significant leap forward over our current capabilities.” DARPA is seeking expertise in a range of technologies on the GRIT program including advanced accelerator technology, high-energy laser systems, novel control systems, and new x-ray and gamma ray detector technology. To register for the GRIT Proposers Day webinar, visit: https://go.usa.gov/xmh28. GRIT's focus on new, compact photon sources for inspection complements DARPA's Intense and Compact Neutron Sources (ICONS) program, which is developing compact neutron sources. The two technologies would work in tandem, yielding a very robust inspection capability. Caption: The Gamma Ray Inspection Technology (GRIT) program seeks tunable gamma ray sources for a host of national security, industrial, and medical applications. https://www.darpa.mil/news-events/2019-06-14

• 

  11 juillet 2024 | International, Aérospatial, Terrestre, Sécurité

  Switzerland squares neutrality with its European air-defense push

  The European Sky Shield Initiative's focus procurement and other non-operational aspects have eased Swiss neutrality concerns, officials and analysts say.