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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Coherence Analysis of the Space Launch System using Unsteady Pressure Sensitive Paint

Transonic buffet forces are a major source of unsteady loading on launch vehicles, thus requiring accurate estimation for efficient vehicle design. The state of the art in modeling these unsteady loads utilizes wind-tunnel tests where the fluctuating pressures are measured by pressure transducers (PTs) at discrete locations on a rigid buffet model. These pressures are then integrated over the surface of the vehicle to yield a series of orthogonal centerline loads called buffet forcing functions (BFFs). Typically, the PT layout aims at resolving the pressure correlation along the longitudinal axis of the vehicle. As a result, the distribution of azimuthal correlation and its impact on the estimated BFFs are not well known. To fill these gaps, extremely high-spatial-resolution uPSP data were collected for three different configurations of the Space Launch System in the NASA Ames Research Center 11-Foot Transonic Unitary Plan Wind Tunnel. The spatio-temporal behavior of the pressure correlation on these vehicles is analyzed and flow features of interest are investigated. It is shown that terminal shocks interacting with turbulence are a source of increased azimuthal coherence, especially when the shock develops at a junction. Vortex shedding off the forward attachment hardware that connects the core stage to the solid rocket boosters (SRBs) is the most severe buffet environment on the vehicle. The associated fluctuating pressures are shown to be highly coherent as far as the vehicle tail and up to 40 degrees away from the boosters. For selected areas of the vehicle, factoring the azimuthal coherence into the attenuation of discrete-measurements-based BFFs results in under prediction relative to the BFFs obtained from full integration of the uPSP data.

buffet↗
NASA NTRSDate not supplied

Analysis of Transonic Unsteady Aerodynamic Environments using Unsteady Pressure Sensitive Paint for the Space Launch System Block 1 Cargo Launch Vehicle

Predicting launch vehicle unsteady aerodynamic loads due to buffet remains a significant challenge. Current practices for modeling buffet environments involve the development of buffet forcing functions using unsteady pressure measurements acquired during wind-tunnel tests. These practices often result in significant uncertainty in buffet environments for coupled loads analyses due to the complex spatio-temporal nature of the unsteady pressure field and challenge of its estimation using discrete sensors. Unsteady pressure sensitive paint, on the other hand, can provide unsteady pressure data at a comparatively high-spatial-density and may overcome the challenge of unsteady pressure field estimation with discrete sensors and lead to improvements in the development of buffet forcing functions. In this paper, comparisons of the fluctuating pressure field are made for the Space Launch System Block 1 cargo launch vehicle measured using unsteady pressure sensitive paint and pressure transducers.

buffet↗
NASA NTRSDate not supplied

Analysis of Transonic Unsteady Aerodynamic Environments using Unsteady Pressure Sensitive Paint for the Space Launch System Block 1 Cargo Launch Vehicle

Predicting launch vehicle unsteady aerodynamic loads due to buffet remains a significant challenge. Current practices for modeling buffet environments involve the development of buffet forcing functions using discrete unsteady pressure measurements acquired during wind-tunnel tests. These practices often result in significant uncertainty in buffet environments for coupled loads analyses due to the complex spatio-temporal nature of the unsteady pressure field and the challenge of its estimation using discrete sensors. Unsteady pressure sensitive paint, on the other hand, can provide unsteady pressure data at a comparatively high spatial density and may overcome the challenge of unsteady pressure field estimation with discrete sensors and lead to improvements in the development of buffet forcing functions. In this paper, comparisons of the fluctuating pressure field are made for the Space Launch System Block 1 cargo launch vehicle measured using unsteady pressure sensitive paint and pressure transducers.

buffet↗
NASA NTRSDate not supplied

Analysis of Transonic Unsteady Aerodynamic Environments using Unsteady Pressure Sensitive Paint for the Space Launch System Block 1 Cargo Launch Vehicle

Predicting launch vehicle unsteady aerodynamic loads due to buffet remains a significant challenge. Current practices for modeling buffet environments involve the development of buffet forcing functions using discrete unsteady pressure measurements acquired during wind-tunnel tests. These practices often result in significant uncertainty in buffet environments for coupled loads analyses due to the complex spatio-temporal nature of the unsteady pressure field and the challenge of its estimation using discrete sensors. Unsteady pressure sensitive paint, on the other hand, can provide unsteady pressure data at a comparatively high spatial density and may overcome the challenge of unsteady pressure field estimation with discrete sensors and lead to improvements in the development of buffet forcing functions. In this paper, comparisons of the fluctuating pressure field are made for the Space Launch System Block 1 cargo launch vehicle measured using unsteady pressure sensitive paint and pressure transducers.

buffet↗
NASA NTRS2015

Common Cause Failure Modeling in Space Launch Vehicles

Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFs are a set of dependent type of failures that can be caused for example by system environments, manufacturing, transportation, storage, maintenance, and assembly. Since there are many factors that contribute to CCFs, they can be reduced, but are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and dependent CCF. Because common cause failure data is limited in the aerospace industry, the Probabilistic Risk Assessment (PRA) Team at Bastion Technology Inc. is estimating CCF risk using generic data collected by the Nuclear Regulatory Commission (NRC). Consequently, common cause risk estimates based on this database, when applied to other industry applications, are highly uncertain. Therefore, it is important to account for a range of values for independent and CCF risk and to communicate the uncertainty to decision makers. There is an existing methodology for reducing CCF risk during design, which includes a checklist of 40+ factors grouped into eight categories. Using this checklist, an approach to produce a beta factor estimate is being investigated that quantitatively relates these factors. In this example, the checklist will be tailored to space launch vehicles, a quantitative approach will be described, and an example of the method will be presented.

Hark, Frank↗
NASA NTRSDate not supplied

Coherence Analysis of the Space Launch System using Unsteady Pressure Sensitive Paint

Transonic buffet during atmospheric ascent is a major source of unsteady loading on launch vehicles that, in the past, has led to structural failures. Thus, determining accurate buffet forcing functions (BFFs) to properly predict the vehicle response to buffet is of vital importance in launch vehicle design. The state of the art for obtaining the BFFs relies on wind-tunnel tests where the fluctuating pressures are measured by pressure transducers (PTs) at sparse locations on a rigid, geometrically-scaled buffet model. To compute the BFFs, the outer mold line (OML) of the vehicle is mapped onto contiguous panels centered at the location of the PTs and the measured fluctuating pressures are integrated over the panels’ areas. To mitigate conservatism due to the assumption that the measured buffet pressures act in phase across each panel, coherence factors are applied, effectively reducing the integration areas and, therefore, the buffet forces. For coherence factors to provide the proper level of BFF attenuation, accurate knowledge of the spatial and temporal correlation of the buffet pressures is paramount. Unfortunately, even with hundreds of unsteady pressure transducers instrumenting the models, compromises must be made on the spatial resolution of the PTs. Typically, the PT layout aims at resolving the pressure correlation along the longitudinal axis of the vehicle, assuming that coherent structures propagate mostly in the longitudinal direction. As a result, the distribution of azimuthal/cross-stream correlation is not well known and its impact on the estimated BFFs is often neglected. To fill this and other knowledge gaps, extremely high spatial-resolution uPSP data were collected for three different production-design configurations of the Space Launch System in the NASA Ames Research Center Unitary Plan Wind Tunnel 11-Foot Transonic Wind Tunnel. Specifically, two cargo configurations, the Block 1 and Block 1B, and one crew configuration, the Block 1B crew, were surveyed at resolutions ranging from 600,000 to over 1 million uPSP measurement locations. To shed light on the temporal and spectral behavior of are presented. Several OML regions and flow features of interest are investigated, from theexpansion/shock on the Orion Multi-Purpose Crew Vehicle, to the terminal shock environment on the core stage, and the Strouhal shedding behind the boosters forward attach. The sensitivity of these environments to the vehicle attitude is examined. Furthermore, for selected panels,coherence factors that accurately capture the azimuthal coherence distribution of the buffetpressures are derived and their impact on the estimated BFFs is discussed. Finally, distributions of the local convection velocity and cross spectrum phase are presented.

buffet↗
NASA NTRS2018

NASA's Space Launch System: Unprecedented Payload Capabilities

As NASA turns 60 and plans to transition the International Space Station (ISS) and other low-Earth orbit (LEO) activities to commercial enterprises, the Agency's human exploration program turns its focus to deep space. With missions planned to send astronauts back to the Moon and to construct a lunar orbiting Gateway for surface access as well as science experiments and technology demonstrations, NASA requires a vehicle with capabilities for launching more mass and volume than is currently commercially available. To that end, NASA and its private sector partners are building the Space Launch System (SLS) super heavy-lift launch vehicle, which will send the new Orion crew capsule, eventually with a complement of four astronauts, to cislunar space for the first time since the Apollo Program in the 1960s and 1970s. NASA Kennedy Space Center's (KSC's) Exploration Ground Systems (EGS) Program has upgraded and refurbished ground and launch facilities to process, assemble and launch NASA's new deep space exploration system, which is managed by the Exploration Systems Development (ESD) organization in the Human Exploration and Operations Mission Directorate (HEOMD). Offering an unmatched combination of power, payload capacity and departure energy, the evolvable SLS features the world's most proven propulsion system: solid rocket boosters and RS-25 main engines with a modified Delta Cryogenic Second Stage (DCSS) cryogenic upper stage. The initial SLS configuration, Block 1, will deliver at least 26 metric tons (t) to trans-lunar injection (TLI). The second variant, Block 1B, will deliver at least 34 t to TLI in its crew configuration and at least 40 t to TLI in its cargo configuration. The Block 1 cargo vehicle will fly with an industry-standard 5 m fairing while the Block 1B cargo configuration will accommodate 8 m-diameter fairings in varying lengths. The Block 2 vehicle will incorporate upgraded boosters and possibly larger fairings for launching Mars-class payloads to deep space. Although designed to enable human exploration of deep space, the vehicle also provides game-changing benefits for large science payloads and even harnesses excess capacity to provide small satellites with access to deep space. Three flights of the Block 1 vehicle are now planned; the first vehicle, being built for a test flight known as Exploration Mission-1 (EM-1), is nearing completion at NASA and contractor sites across the United States. In fact, hardware for the second mission has also been built. This paper will provide an overview of the SLS vehicle, with a focus on its payload accommodations and the missions enabled by the unprecedented payload volume and departure energy of SLS. This paper also describes the status of the manufacturing and integration for first flight and beyond.

Exploration Mission-1↗
NASA NTRS2014

Flight Testing of the Space Launch System (SLS) Adaptive Augmenting Control (AAC) Algorithm on an F/A-18

The Marshall Space Flight Center (MSFC) Flight Mechanics and Analysis Division developed an adaptive augmenting control (AAC) algorithm for launch vehicles that improves robustness and performance on an as-needed basis by adapting a classical control algorithm to unexpected environments or variations in vehicle dynamics. This was baselined as part of the Space Launch System (SLS) flight control system. The NASA Engineering and Safety Center (NESC) was asked to partner with the SLS Program and the Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP) to flight test the AAC algorithm on a manned aircraft that can achieve a high level of dynamic similarity to a launch vehicle and raise the technology readiness of the algorithm early in the program. This document reports the outcome of the NESC assessment.

Dennehy, Cornelius J.↗
NASA NTRSDate not supplied

An Overview of the Meteorological Instrumentation Utilized for the Design and Operations of Space Launch Vehicles

One of the first hurdles a space vehicle must overcome is the ability to successfully traverse Earth’s atmosphere. In order to achieve this goal, there must exist both climatological and real-time atmospheric data from the surface to the Karman line. The Natural Environments Branch at the National Aeronautics and Space Administration’s Marshall Space Flight Center utilizes both traditional and specialized meteorological instrumentation to aide in both the design and operations of launch vehicles. Weather balloons measuring thermodynamic and wind data from 0 - 70 kft are an example of the more traditional instrumentation. While the Tropospheric Doppler Radar Weather Profiler that measures winds from roughly 5 kft – 60 kft every five minutes is an example of a more specialized instrument. Other instruments include: 915 MHz Doppler Radar Wind Profilers, rain gauges, meteorological towers, lightning detection networks, Automated Weather Observing System stations, Mobile Launcher weather stations, and more. This presentation will give a high-level overview of which instruments are utilized, how the data are acquired, and how the data are ultimately used in design and/or operations.

Nathan L. Curtis↗
NASA NTRSDate not supplied

NASA’s SLS (Space Launch System) Rocket Ready for Artemis II Lunar Mission

In early 2026, NASA will launch the Artemis II mission, an approximately 10-day long lunar mission that will fly three NASA astronauts and one CSA (Canadian Space Agency) astronaut on a free-return trajectory around the Moon, following a one-day checkout of their Orion spacecraft in Earth orbit. The mission will be the first to launch astronauts aboard NASA’s Orion spacecraft and on top of the agency’s SLS (Space Launch System) rocket. The mission will also deploy four 12U CubeSats as secondary payloads from the Orion stage adapter, following Orion separation and departure. The payloads, developed by four of NASA’s international partners, will perform a variety of science and technology investigations. The SLS and Orion for the mission are currently stacked in the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center in Florida and are undergoing final preparations to rollout to Launch Pad 39B for a tanking test before launch. In addition to preparations for the Artemis II mission, significant progress is being made on the SLS for the Artemis III mission, which is targeted to return astronauts to the lunar surface no later than 2029. Major components of the core stage and solid rocket boosters are already at NASA Kennedy undergoing build-up for the mission. Data from the Artemis II launch and mission, as well as progress to subsequent missions, as available, will be presented.

Bruce R Askins↗
NASA NTRSDate not supplied

NASA’s SLS (Space Launch System) Rocket Ready for Artemis II Lunar Mission

In early 2026, NASA will launch the Artemis II mission, an approximately 10-day long lunar mission that will fly three NASA astronauts and one CSA (Canadian Space Agency) astronaut on a free-return trajectory around the Moon, following a one-day checkout of their Orion spacecraft in Earth orbit. The mission will be the first to launch astronauts aboard NASA’s Orion spacecraft and on top of the agency’s SLS (Space Launch System) rocket. The mission will also deploy four 12U CubeSats as secondary payloads from the Orion stage adapter, following Orion separation and departure. The payloads, developed by four of NASA’s international partners, will perform a variety of science and technology investigations. The SLS and Orion for the mission are currently stacked in the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center in Florida and are undergoing final preparations to rollout to Launch Pad 39B for a tanking test before launch. In addition to preparations for the Artemis II mission, significant progress is being made on the SLS for the Artemis III mission, which is targeted to return astronauts to the lunar surface no later than 2029. Major components of the core stage and solid rocket boosters are already at NASA Kennedy undergoing build-up for the mission. Data from the Artemis II launch and mission, as well as progress to subsequent missions, as available, will be presented.

Bruce Askins↗