UAM Noise Working Group Meeting Subgroup 2: Ground & Flight Testing
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Devin Boyle↗
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UAM Noise Working Group Meeting Subgroup 2: Ground & Flight Testing
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Urban Air Mobility↗
X-57 Mod III Wing Ground Vibration Test
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Samson Truong↗
Mock Truss-Braced Wing Ground Vibration Test using the Fixed-Base Correction Method
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Benjamin Park↗
A review of the impact of ground test-related facility effects on gridded ion thruster operation and performance
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John E. Foster↗
Digital Image Correlation Techniques Applied to Large Scale Rocket Engine Testing
Rocket engine hot-fire ground testing is necessary to understand component performance, reliability and engine system interactions during development. The J-2X upper stage engine completed a series of developmental hot-fire tests that derived performance of the engine and components, validated analytical models and provided the necessary data to identify where design changes, process improvements and technology development were needed. The J-2X development engines were heavily instrumented to provide the data necessary to support these activities which enabled the team to investigate any anomalies experienced during the test program. This paper describes the development of an optical digital image correlation technique to augment the data provided by traditional strain gauges which are prone to debonding at elevated temperatures and limited to localized measurements. The feasibility of this optical measurement system was demonstrated during full scale hot-fire testing of J-2X, during which a digital image correlation system, incorporating a pair of high speed cameras to measure three-dimensional, real-time displacements and strains was installed and operated under the extreme environments present on the test stand. The camera and facility setup, pre-test calibrations, data collection, hot-fire test data collection and post-test analysis and results are presented in this paper.
Gradl, Paul R.↗
Arcjet Semi-Elliptic Nozzle Simulations and Validation in Support of TPS Testing
Much of the ground based testing of advanced thermal protection system (TPS) components for the X33 program is done in arc-heated wind tunnels such as those located in the Arc-Jet Complex at NASA Ames Research Center. These facilities are capable of simulating the high temperature, chemically reacting flow environment experienced by the vehicle during flight. This allows one to test critical design issues such as maximum reuse temperatures, seals, gaps, and increases in heating due to interfaces between different materials. Computational fluid dynamics (CFD) has evolved to the point where it now can be used in the vehicle design process for accurate and timely prediction of trajectory based aerothermal heating environments for re-entry vehicles. It can also be used for simulation of the flow environments in ground based facilities such as arcjets. By utilization of the same CFD code and solution methodology, the important differences between ground test and flight may be quantified. The goal of this paper is to utilize CFD to provide validated simulations of the flow environment in the NASA-Ames semi elliptic nozzle arcjet facilities. The validation of the ground simulations will come From comparison to existing calibration data. Specific tests in support of the X33 TPS test program will ilso be simulated. In this manner, the differences between the ground test simulation and the flight environment can be identified for a measure of ground test to flight traceability.
Loomis, Mark↗
HiMAT structural development design methodology
In order to improve aerodynamic performance, a twist criterion was used to design the canard and wing lifting surfaces of two graphite-epoxy research aircraft. To meet that twist criterion, the lifting surfaces were tailored using graphite-epoxy tape. The outer surface of the aircraft is essentially constructed of 95 percent graphite epoxy materials. The analytical tools and methodology used to design those lifting surfaces are described. One aircraft was subjected to an 8g ground test in order to verify structural integrity and to determine how well the desired twist was achieved. Test results are presented and the reductions of both flight and ground strain test gages and their associated stresses are discussed.
Price, M. A.↗
Development and flight tests of vortex-attenuating splines
The ground tests and full-scale flight tests conducted during development of the vortex-attenuating spline are described. The flight tests were conducted using a vortex generating aircraft with and without splines; a second aircraft was used to probe the vortices generated in both cases. The results showed that splines significantly reduced the vortex effects, but resulted in some noise and climb performance penalties on the generating aircraft.
Hastings, E. C., Jr.↗
Flexural Fillet Geometry Optimization for Design of Force Transducers Used in Aeronautics Testing
Force transducer designs used in the ground testing aeronautics community have seen minimal change over the last few decades. With increased focus on data quality and long- term performance capabilities over the life of these instruments, it is critical to investigate new methods that improve these designs. One area of focus in the past few years at NASA has been on the design of the exural elements of traditional force balance transducers. Many of the heritage balances that have been heavily used over the last few decades have started to develop fatigue cracks. The recent focus on the exural design of traditional single-piece force balances revolves around the design of these elements such that stress concentrations are minimized, with the overall goal of increasing the fatigue life of the balance. Recent research in the area of using conic shaped llets in the highly stressed regions of traditional force balances will be discussed, with preliminary numerical and experimental data results. A case study will be presented which discusses integration of this knowledge into a new high-capacity semi-span force balance
Lynn, Keith C.↗
Flexural Fillet Geometry Optimization for Design of Force Transducers Used in Aeronautics Testing
Force transducer designs used in the ground testing aeronautics community have seen minimal change over the last few decades. With increased focus on data quality and long-term performance capabilities over the life of these instruments, it is critical to investigate new methods that improve these designs. One area of focus in the past few years at NASA has been on the design of the flexural elements of traditional force balance transducers. Many of the heritage balances that have been heavily used over the last few decades have started to develop fatigue cracks. The recent focus on the flexural design of traditional single-piece force balances revolves around the design of these elements such that stress concentrations are minimized, with the overall goal of increasing the fatigue life of the balance. Recent research in the area of using conic shaped fillets in the highly stressed regions of traditional force balances will be discussed, with preliminary numerical and experimental data results. A case study will be presented which discusses integration of this knowledge into a new high-capacity semi-span force balance.
Lynn, Keith C.↗
Affordable Development and Demonstration of a Small Nuclear Thermal Rocket (NTR) Engine and Stage: How Small Is Big Enough?
The Nuclear Thermal Rocket (NTR) derives its energy from fission of uranium-235 atoms contained within fuel elements that comprise the engine's reactor core. It generates high thrust and has a specific impulse potential of approximately 900 specific impulse - a 100 percent increase over today's best chemical rockets. The Nuclear Thermal Propulsion (NTP) project, funded by NASA's Advanced Exploration Systems (AES) program, includes five key task activities: (1) Recapture, demonstration, and validation of heritage graphite composite (GC) fuel (selected as the Lead Fuel option); (2) Engine Conceptual Design; (3) Operating Requirements Definition; (4) Identification of Affordable Options for Ground Testing; and (5) Formulation of an Affordable Development Strategy. During fiscal year (FY) 2014, a preliminary Design Development Test and Evaluation (DDT&E) plan and schedule for NTP development was outlined by the NASA Glenn Research Center (GRC), Department of Energy (DOE) and industry that involved significant system-level demonstration projects that included Ground Technology Demonstration (GTD) tests at the Nevada National Security Site (NNSS), followed by a Flight Technology Demonstration (FTD) mission. To reduce cost for the GTD tests and FTD mission, small NTR engines, in either the 7.5 or 16.5 kilopound-force thrust class, were considered. Both engine options used GC fuel and a common fuel element (FE) design. The small approximately 7.5 kilopound-force criticality-limited engine produces approximately157 thermal megawatts and its core is configured with parallel rows of hexagonal-shaped FEs and tie tubes (TTs) with a FE to TT ratio of approximately 1:1. The larger approximately 16.5 kilopound-force Small Nuclear Rocket Engine (SNRE), developed by Los Alamos National Laboratory (LANL) at the end of the Rover program, produces approximately 367 thermal megawatts and has a FE to TT ratio of approximately 2:1. Although both engines use a common 35-inch (approximately 89-centimeters) -long FE, the SNRE's larger diameter core contains approximately 300 more FEs needed to produce an additional 210 thermal megawatts of power. To reduce the cost of the FTD mission, a simple one-burn lunar flyby mission was considered to reduce the liquid hydrogen (LH2) propellant loading, the stage size and complexity. Use of existing and flight proven liquid rocket and stage hardware (e.g., from the RL10B-2 engine and Delta Cryogenic Second Stage) was also maximized to further aid affordability. This paper examines the pros and cons of using these two small engine options, including their potential to support future human exploration missions to the Moon, near Earth asteroids (NEA), and Mars, and recommends a preferred size. It also provides a preliminary assessment of the key activities, development options, and schedule required to affordably build, ground test and fly a small NTR engine and stage within a 10-year timeframe.
Spacecraft design↗
A New Flow-Through Wind Tunnel Balance for Retropropulsion Testing
Supersonic retropropulsion is believed to be an enabling technology for large-scale human Mars lander vehicle concepts. Ground testing of such vehicles requires the development of new flow-through wind tunnel balances because no suitable balances exist. A new flow-through balance is designed that employs membranes in place of bellows, which have historically been used, and that passes the flow through load bearing parts of the balance. Flow through the balance is optimized via the addition of flow guides, which are manufactured as separate parts, and attached to the balance. Calibration of this new flow-through balance demonstrates that it can suitably characterize the load and pressure ranges it was designed for, which provides aero researchers a new tool to directly measure supersonic retropropulsion performance of powered descent vehicles.
Flow through balance↗
A New Flow-Through Balance for Retropropulsion Testing
Supersonic retropropulsion is believed to be an enabling technology for large-scale human Mars lander vehicle concepts. Ground testing of such vehicles requires the development of new flow-through wind tunnel balances because no suitable balances exist. A new flow-through balance is designed that employs membranes in place of bellows, which have historically been used, and that passes the flow through load bearing parts of the balance. Flow through the balance is optimized via the addition of flow guides, which are manufactured as separate parts, and attached to the balance. Calibration of this new flow-through balance demonstrates that it can suitably characterize the load and pressure ranges it was designed for, which provides aero researchers a new tool to directly measure supersonic retropropulsion performance of powered descent vehicles.
Flow through balance↗
Contrails Measurement and Testing Capabilities in NASA's Particulate Aerosol Laboratory
The NASA Glenn Research Center Particulate Aerosol Laboratory (PAL) is a ground test facility for studying emissions and contrails at upper atmospheric conditions. The facility consists of a small-scale combustor that generates hot combustion gases and soot nanoparticles, which flow through a transition pipe into a jet nozzle, which exhausts into an altitude chamber. Thermodynamic conditions experienced in flight are matched in the altitude chamber, allowing the study of ice particle formation of simulated aircraft engine exhaust plumes. A non-intrusive optical diagnostic technique based on Mie scattering provides ice particle size, number density, and mass density. A suite of commercial extractive particle measurement instruments provides estimates of soot number density, size, and black carbon mass distributions. Measurements are presented for various fuels at chamber conditions covering an altitude range of 20,000 ft (6 km) to 45,000 ft (14 km) altitude and ambient temperatures from -48°C to -68°C. The data presented demonstrate the effect of soot number density, altitude, and fuel-to-air equivalence ratio on the contrail ice particle formation. Ice mass density measurements are compared to values predicted by a thermodynamic plume similarity solution.
Optical Instrumentation↗
ROTOR: Research to Operations and Operations to Research
PNNL’s Research to Operations/Operations to Research (ROTOR) Program fosters a cybersecurity operations to researcher collaboration, identifying hard problems and challenges for cyber defenders and bringing researcher science disciplines to these challenges. ROTOR allows PNNL’s cyber defenders to better protect the laboratory but also fosters innovation and incubation of solutions for our sponsor missions across DOE, DOD, DHS and the intelligence community. Our sponsors and their missions are faced with many of the same cyber defense challenges that PNNL faces. By using our own laboratory security operations environment as an innovation generator and testing ground, allowing research to be tested and tried, our sponsors are directly benefitted. PNNL is in a unique position to combine our world class research organization with enterprise cybersecurity operations. ROTOR is taking advantage of this to bring PNNL cybersecurity research projects into an operational environment within PNNL’s Cyber Security Operations Center. With ROTOR, PNNL researchers gain the advantage of operational experience and expertise and have an avenue for showcasing research in an operational environment. This helps to advance PNNL research, prove operability of PNNL projects to its sponsors, and provide real-world insight to real-world problems for our cybersecurity research agenda. ROTOR is the conduit for PNNL cybersecurity research to find its way to operational use. PNNL researchers and engineers are informed by real-world operations and operations has access to current PNNL research and engineering capabilities. All of this leads to improved reputation for PNNL as a provider of national security solutions that are tried and tested. To date, ROTOR has collaborated with six projects, enabling each to conduct operational work within the CSOC.
97 MATHEMATICS AND COMPUTING↗
Large space structures activity at MSFC
This paper describes a broad based set of activities which have been undertaken at the Marshall Space Flight Center (MSFC) developing technologies necessary to emplace and operate large structures in space. Progress has been made in the development of processes and equipment needed for the in space fabrication of structural members in both aluminum and graphite composite materials. Designs for member joining attachments have been completed and the evaluation of procedures for structural assembly have been simulated and evaluated utilizing the MSFC Neutral Buoyancy Facility. A concept of a flight test necessary for flight verification of the technologies for space fabrication, assembly, and operation of large space structure is described. Recently initiated is a project to develop design characteristics of a deployable structure required for the Science and Applications Space Platform (SASP). This is being accomplished through the design, fabrication, analysis, and test of a full scale ground test article which reflects the influence of system requirements of the SASP. Development of designs for erectable/deployable structures which are modular and have various applications to large space structures is in progress.
Denton, S. J.↗
Shuttle flight data analysis
As the STS moves into routine operations, the direction of the work is shifting to an in-depth assessment of performance and its impact on the design and development of a future generation of vehicles. Particular emphasis is placed on providing an accurate physical explanation of anomalies, assessing the quality of simulation provided by the ground test facilities utilized, understanding the ground to flight extrapolation procedures, and the limitations of theoretical prediction techniques. The results are expected to provide direction and focus for future research and technology programs to enable substantial technological improvements in the next generation vehicles. The recent approval of the Orbital Experiments (OEX) Program's Shuttle Infrared Leeside Temperature Sensing (SILTS), Shuttle Entry Air Data System (SEADS), and Shuttle Upper Atmospheric Mass Spectrometer (SUMS) experiments to be integrated for flight on OV-102 in late 1985 is a firm indication of a strong commitment to a continuing and vigorous program in shuttle flight data analysis.
Walberg, G. D.↗