Test & Measurement

In-Flight Pitot-Static Calibration

This precise yet time- and cost-effective method is based on GPS technology using output error optimization.

Langley Research Center, Hampton, Virginia

NASA’s Langley Research Center has developed a new method for calibrating pitot-static air data systems used in aircraft. Pitot-static systems are pressure-based instruments that measure the aircraft’s airspeed. These systems must be calibrated in flight to minimize potential error. Current methods — including trailing cone, tower fly-by, and pacer airplane — are time- and cost-intensive, requiring extensive flight time per calibration. NASA’s method can reduce this calibration time by up to an order of magnitude, cutting a significant fraction of the cost. In addition, NASA’s calibration method enables near-real-time monitoring of error in airspeed measurements, which can be used to alert pilots when airspeed instruments are inaccurate or failing. Because of this feature, the technology also has applications in the health usage and monitoring (HUMS) industry. Flight test engineers can be trained to use this method proficiently in 12 days without costly specialized hardware.

Posted in: Briefs, Test & Measurement, Calibration, Pitot-static instruments

Real-Time Radiation Monitoring Using Nanotechnology

Ames Research Center, Moffett Field, California

NASA has patented a unique chemical sensor array leveraging nanostructures for monitoring the concentration of chemical species or gas molecules that is not damaged when exposed to protons and other high-energy particles over time. The nanotechnology-enabled chemical sensor array uses single walled carbon nanotubes (SWCNTs), metal catalyst-doped SWCNTs, and polymer- coated SWCNTs as the sensing media between a pair of interdigitated electrodes (IDE). By measuring the conductivity change of the SWCNT device, the concentration of the chemical species or gas molecules can be measured. These sensors have high sensitivity, low power requirements, and are robust and have a low manufacturing cost compared to other commercial chemical sensors for detection of trace amount of chemicals in gasses and liquids.

Posted in: Briefs, Test & Measurement, Sensors and actuators, Nanotechnology, Radiation

External Diagnostic Method to Detect Electrical Charging in Complex Ion Trapping Systems

This procedure is implemented without breaking the vacuum and/or disassembling the system.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Electron-ionized atom trapping technology is widely used in mass spectrometry and atomic clocks. The complexity of the trapping configuration operating in an ultra-high vacuum system is driven by demands for ultimate sensitivity, performance, and fundamental science. Consequently, external diagnosis, maintenance, and design verification and validation without opening the vacuum and disassembling the system become increasingly difficult. In these ion trapping configurations, electrical charging of non-metallic materials or opening connections are a hard-to-detect problem, yet can easily compromise the intended trapping potential. More specifically, the JPL Linear Ion Trap Standards (LITS) will benefit from a non-invasive solution for system verification/validation, diagnosis, maintenance, and troubleshooting.

Posted in: Briefs, Test & Measurement, Electrical systems, Spectroscopy, Diagnostics

Sonar Inspection Robot System

The system surveys interior volume, interrogates structure integrity, and displays real-time video and sonar.

Lyndon B. Johnson Space Center, Houston, Texas

The robotic inspection device prototype that was used for testing.

NASA’s Johnson Space Center innovators have designed a Robotic Inspection System that is capable of surveying deep sea structures such as oil platform storage cells/tanks and pipelines in order to determine the volume of material remaining inside, interrogate structure integrity, and display real-time video and sonar. This inspection device and method could significantly reduce the cost of inspecting, and in the future, provide sampling of the structure contents. The technology is an all-in-one inspection device that includes cameras, sonar, and motion-sensing instruments with hardware and software components. This NASA-developed technology is available for licensing.

Posted in: Briefs, Test & Measurement, Robotics, Inspections, Test equipment and instrumentation

Modules for Inspection, Qualification, and Verification of Pressure Vessels

This automated, modular, standardized system features interchangeable probes.

Lyndon B. Johnson Space Center, Houston, Texas

After decades of composite over-wrapped pressure vessel (COPV) development, manufacturing variance is still high, and has necessitated higher safety factors and additional mass to be flown on spacecraft, reducing overall performance. When liners are used in COPVs, they need to be carefully screened before wrapping. These flaws can go undetected and later grow through the thickness of the liner, causing the liner to fail, resulting in a massive leakage of the liner and subsequent mission loss.

Posted in: Briefs, Test & Measurement, Aircraft structures, Composite materials, Inspections, Spacecraft

Hermetic Seal Leak Detection Apparatus with Variable Size Test Chamber

A streamlined, cost-effective, sensitive approach to detecting leaks in hermetic seals.

Marshall Space Flight Center, Alabama

NASA’s Marshall Space Flight Center has developed a unique apparatus ideal for use in nondestructive testing (NDT) of hermetic seals of containers or instrumentation. The device is capable of detecting both large and small leaks and can be calibrated to characterize the relative leak rate. Its simple design does not require specialized gases for pressurization and detection, and eliminates the need for expensive instrumentation such as a mass spectrometer to analyze leaks and achieve high sensitivity. Low in cost and simple to manufacture, the patent-pending technology is ideal for use in many industries, from aerospace applications to food packaging and commercial goods.

Posted in: Briefs, Test & Measurement, Containers, Seals and gaskets, Non-destructive tests, Test equipment and instrumentation

Extreme Low Frequency Acoustic Measurement System

This system detects and locates atmospheric clear air turbulence and severe weather.

Langley Research Center, Hampton, Virginia

NASA’s Langley Research Center has developed a system to detect and locate atmospheric clear air turbulence (CAT) by means of a ground-based infrasonic array to serve as an early warning system for aircraft. This system could augment existing systems such as pilot reports (PIREPs), airborne lidar, and airborne radar. The NASA system offers a benefit since the existing electromagnetic methods lack targets at 30,000-40,000 feet and will not detect CAT. Because CAT and severe storms emit infrasound that propagates over vast distances through the Earth’s atmosphere, the Langley system offers an excellent early warning opportunity. The system has been able to detect known events — such as detection of the launch of the Space Shuttle in Florida all the way from Virginia. It also has correlated data with NOAA’s PIREPs information.

Posted in: Briefs, Test & Measurement, Measurements, Weather and climate, Acoustics, Turbulence

Low-Temperature Radiometer

This technology can look for heat leaks and reflected flux in low-temperature thermal vacuum systems.

Goddard Space Flight Center, Greenbelt, Maryland

Many present and future NASA missions require high-performance, large-scale cryogenic systems, such as the sunshields and cold instruments for the James Webb Space Telescope (JWST). Testing these systems is problematic because of both the size and the low heat loads allowed. The heat loads can be greatly influenced by non-ideal blackbody characteristics of the test chamber, and by stray heat from warmer parts of the system and ground support equipment. Previously, stray thermal energy was not directly measured, but inferred from deviations in the expected results, which leads to errors in thermal modeling and in lack of knowledge of the thermal performance of the item under test. Technologists at NASA Goddard Space Flight Center have developed a radiometer to help identify the sources of stray heat and to make non-contact thermal emission measurements of such materials as vapor-deposited aluminum on Kapton and multilayer insulation blankets, as well as background measurements of non-ideal chamber effects such as light leaks and radiation bounces.

Posted in: Briefs, Test & Measurement, Optics, Radiation, Thermal testing, Satellites

Lightweight Internal Device to Measure Tension in Hollow-Braided Cordage

This device has applications in industries commonly using cordage, such as shipping, sailing, and lifting.

NASA’s Jet Propulsion Laboratory, Pasadena, California

The suspension system of parachutes is typically made from ropes (referred to as cordage). Measuring loads in the suspension system cordage has thus far proven very challenging because of the dynamic nature of the parachute. The suspension lines must be deployed along with the parachute, and experience rapid acceleration and dynamic motion as the parachute inflates. The addition of bulky load cells to the suspension lines would change the dynamics of the system and corrupt the data.

Posted in: Briefs, Test & Measurement, Suspension systems, Measurements, Fibers, Tensile Strength

Improved Method to Quantify Leak Rates

This method improves the quality and reliability of leak rate test results.

John H. Glenn Research Center, Cleveland, Ohio

One existing method to quantify the gas loss from a closed system is the mass point leak rate method. This traditional empirical method is capable of quantifying the loss of a known type of gas from a volume of known size. Using this method, measurement devices quantify the gas pressure and temperature within a closed system throughout the duration of the test. At the onset of the test, the operator establishes boundary conditions to create a pressure differential across the test article that is higher than the pressure differential of interest. During the test, the pressure differential decreases due to leakage. When the operator subjectively determines that the desired pressure differential has been achieved and sufficient data has been collected, the test is stopped. Subsequently, the data analyst identifies a subset of the collected data to be used for mass loss computations. A typical computation utilizes a linear fit of the mass-time data set, wherein the slope of the line is the mass loss rate. It is common to use the largest data subset to minimize the measurement uncertainty; however, the data set must not be so large that the curve fit is nonlinear.

Posted in: Briefs, Test & Measurement, Mathematical analysis, Gases, Test procedures

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