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Using System Simulation to Manage Increasing Thermal Loads on Aircraft Fuel Systems

Today’s modern military fighter jets are like “a flying thermos bottle” according to Steve Iden, AFRL Invent Program Manager [1]. Many engineers have been saddled with trying to put the thermal loading constraints of these fighter jets on ice. This places increasing demands on utilizing the fuel system as a heat sink to dissipate thermal loads coming from onboard electronics, oil and hydraulic systems, avionics bay cooling, and weapons modules. Engineers today are looking to simulation to help tackle these design challenges, and they have more power than ever with simulating fuel systems to evaluate feasible system designs with given requirements on thermal power loading, fuel capacity, and tank geometry. With a given set of key performance metrics and limits on a design, the design space can be quickly explored to find optimum metrics such as flight mission duration or required component sizing to meet thermal load requirements.

Posted in: Articles, Aerospace, Defense
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Ensuring the Compliance of Avionics Software with DO-178C

Given the needs to meet the most stringent requirements for reliability, safety, and security resulting in lengthy software development schedules, aerospace and defense projects have become among the most challenging to complete. In response to the increasing size and complexity of software used in airborne systems, the guidance document for certifying such systems has gone through numerous revisions with the latest being DO-178C.

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Microwave Photonic Notch Filter

Helps Ensure Critical Mission Success

Interference mitigation is crucial in modern radio frequency (RF) communications systems with dynamically changing operating frequencies, such as cognitive radios, modern military radar, and electronic warfare (EW) systems. To protect sensitive RF receivers in these systems, frequency agile RF filters that can remove interferers or jammers with large variations in frequency, power, and bandwidth are critically sought. Unfortunately, an RF bandstop or notch filter that can simultaneously provide high resolution, high peak attenuation, large frequency tuning, and bandwidth reconfigurability does not presently exist. Microwave photonic (MWP) filters are capable of tens of gigahertz tuning and have advanced in terms of performance, but most are limited in stopband rejection due to the challenge in creating a high-quality-factor optical resonance used as the optical filter. To achieve MWP filters with similar performance to state-of-the-art RF filters in terms of isolation bandwidth and rejection is still very challenging, especially in compact integrated photonic chip footprint.

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The Rapid Rise of Beryllium-Aluminum Alloys in Aerospace

Enhanced performance operating envelopes for aerospace platforms continue to challenge industry limits. Aerospace platform operators demand extreme performance in harsh environments from the aircraft, UAVs, and satellites they deploy today: lighter weight, greater strength, superior fuel efficiency and operational range, vibration-mitigated platforms, low coefficients of thermal expansion, better corrosion resistance — the list goes on.

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Aeroacoustic Simulation Delivers Breakthroughs in Aircraft Noise Reduction

Aircraft manufacturers face increasingly stringent standards for reducing community noise. Conventional aircraft development methods based on engineering experience, past designs and flight testing will not suffice to meet future noise reduction targets. Computational Fluid Dynamics (CFD) software based on so-called Reynolds-averaged Navier-Stokes (RANS) methods has revolutionized aerodynamics engineering, but is insufficient for high-fidelity aeroacoustic simulation. However, the Lattice-Boltzmann-based technology of Exa Corporation’s PowerFLOW software provides aeroacoustic simulation accuracy comparable to wind tunnels and flight testing.

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Towed Airborne Plume Simulator

Arnold Engineering Development Complex
Arnold Air Force Base, TN
931-454-5655
For more info click here

A team of engineers at AEDC are supporting the continued development and testing of the Towed Airborne Plume Simulator (TAPS), a simulator that can be towed behind aircraft for testing missile warning and infrared countermeasure systems. Most recently the AEDC TAPS team assisted the Air Force Research Laboratory with a mission in Australia.

Posted in: Application Briefs, Aerospace, Defense
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3D Printed Primary Flight Control Component

Liebherr-Aerospace & Transportation SAS
Toulouse, France
+49 8381 46 4403
For more info click here

Airbus recently successfully flew Liebherr-Aerospace's 3D printed spoiler actuator valve block on a flight test A380. It was the first 3D printed primary flight control hydraulic component flown on an Airbus aircraft.

Posted in: Application Briefs, Aerospace, Defense
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F-16 Upgrades

Lockheed Martin
Bethesda, MD
817-777-6148
For more info click here

The U.S. Air Force recently authorized extending the service life of the Lockheed Martin F-16's designed service life to 12,000 Equivalent Flight Hours — far beyond the aircraft's original design service life of 8,000 hours.

Posted in: Application Briefs, Aerospace, Defense
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NeXtRAD SDR Interface

Pentek, Inc.
Upper Saddle River, NJ
201-818-5900
For more info click here

NeXtRAD is a dual-band, dual-polarization, multistatic radar system under development at the University of Cape Town (UCT) in collaboration with University College London (UCL). The primary mission of the system is to collect multistatic data of small radar cross-section maritime targets embedded in sea clutter.

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Measuring Propellant Stress Relaxation Modulus Using Dynamic Mechanical Analyzer

New testing technique requires less material, gives more accurate results.

Structural analysis of solid rocket motors is challenging for several reasons, but the most important of these is the complex behavior of the propellant. The mechanical response of a solid propellant is time and temperature dependent. The complexity of the mathematical analysis of the propellant depends on the loading conditions, but for some loading situations, the linear viscoelasticity assumption is reasonable. In particular, linear viscoelasticity is perhaps the most appropriate material behavior description for use in the simulations of stresses related to storage conditions. Typically, simulations use a viscoelastic model in the form of a Prony series and a Williams–Landel–Ferry (WLF) equation. The parameters in these models are derived from stress relaxation experiments, making the stress relaxation experiment a key viscoelastic test, analogous to the tensile test for linear elastic materials.

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