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Solar proton events (SPEs) represent the single-most significant source of acute radiation exposure during space missions. Historically, an exponential in rigidity (particle momentum) fit has been used to express the SPE energy spectrum using GOES data up to 100 MeV. More recently, researchers have found that a Weibull fit better represents the energy spectrum up to 1000 MeV (1 GeV). In addition, the availability of SPE data extending up to several GeV has been incorporated in analyses to obtain a more complete and accurate energy spectrum representation. In this paper we discuss the major SPEs that have occurred over the past five solar cycles (~50+ years) in detail - in particular, Aug 1972 and Sept & Oct 1989 SPEs. Using a high-energy particle transport/dose code, radiation exposure estimates are presented for various thicknesses of aluminum. The effects on humans and spacecraft systems are also discussed in detail.

Although Unmanned Aircraft Systems (UAS) have now for some time been used in segregated airspace where separation from other air traffic can be assured, potential users have interests to deploy UAS in non segregated airspace. Recent technological and operational improvements give reason to believe that UAS safety and performance capabilities are maturing. But the skies can only really open up to UAS when there is an agreed upon UAS safety policy with commonly accepted UAS Safety Risk Management (SRM) processes enabling to show that the risks related to UAS operations in all the different airspace classes can be adequately controlled. The overall objective is to develop a UAS SRM framework, supporting regulators and applicants through provision of detailed guidelines for each SRM step to be conducted, including 1) system description, 2) hazard identification, 3) risk analysis, 4) risk assessment, 5) risk treatment.

NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.

Aerodynamic effects induced from vectoring an exhaust jet are investigated using a well established thin-layer Reynolds averaged Navier-Stokes code. This multiple block code has been modified to allow for the specification of jet properties at a block face. The applicability of the resulting code for thrust vectoring applications is verified by comparing numerically and experimentally determined pressure coefficient distributions for a jet-wing afterbody configuration with a thrust-vectoring 2-D nozzle. Induced effects on the body and nearby wing from thrust vectoring are graphically illustrated.

Recent changes in DoD procurement directives have encouraged the purchase of civilian products for use in certain military applications. One such application is the upgrade of avionics suites with the Global Positioning System (GPS) in military air transport aircraft to meet joint civil-military operational requirements. This paper reviews the Commercial Off-the-Shelf (COTS) concept and the proper use of TSOs, ACs, and FARs in both the design and integration process.

Recently a new emphasis has been placed on engineering applications of space radiation analyses and thus a systematic effort of Verification, Validation and Uncertainty Quantification (VV&UQ) of the tools commonly used for radiation analysis for vehicle design and mission planning has begun. There are two sources of uncertainty in geometric discretization addressed in this paper that need to be quantified in order to understand the total uncertainty in estimating space radiation exposures. One source of uncertainty is in ray tracing, as the number of rays increase the associated uncertainty decreases, but the computational expense increases. Thus, a cost benefit analysis optimizing computational time versus uncertainty is needed and is addressed in this paper. The second source of uncertainty results from the interpolation over the dose vs. depth curves that is needed to determine the radiation exposure.

This paper describes the recently established Commercial Aviation Alternative Fuel Initiative (CAAFI), including its goals and objectives, as well as presents an alternate fuel roadmap that was originally generated by industry and refined by the CAAFI stakeholders. CAAFI is designed to coordinate the development and commercialization of “drop-in” alternate fuels (i.e. fuels that can directly supplement or replace crude oil derived jet fuels), as well as exploring the long-term potential of other fuel options. The ultimate goal is to ensure an affordable and stable supply of environmentally progressive aviation fuels that will enable continued growth of commercial aviation. This initiative is organized into four sub-groups: Research and Development (R&D), certification, environment, and economics & business. The R&D group seeks to identify promising new drop-in alternate fuels, and to foster coordination of development efforts.

Many of the certification regulations in 14 CFR Part 25 are by design, broad and as such, can be subject to large differences in the interpretation of what constitutes adequate compliance. Advisory Circulars (AC's) were developed for many of the regulations to assist industry, as well as certification personnel, with what is considered an acceptable, but not the only means, of compliance. However, there are many regulations where no advisory material is available. In these cases, the “acceptable means” of compliance can vary to a greater degree among the various aircraft certification offices. This difficulty is aggravated as new applicants and regulatory personnel enter the certification field. Recent discussions and interpretations on the usage of an avionic unit's mean time between failure or MTBF for its detectable faults as the basic repair rate for undetected or latent faults, is a subject area where no significant advisory material exists.

This paper presents a simplified orbit analysis program developed to calculate orbital parameters for the thermal analysis of spacecraft and space-flight instruments. The program calculates orbit data for inclined and sunsynchronous earth orbits. Traditional orbit analyses require extensive knowledge of orbital mechanics to produce a simplified set of data for thermal engineers. This program was created to perform orbital analyses with minimal input and provides the necessary output for thermal analysis codes. Engineers will find the program to be a valuable analysis tool for fast and simple orbit calculations. A description of the program inputs and outputs is included. An overview of orbital mechanics for inclined and Sun-synchronous orbits is also presented. Finally, several sample cases are presented to illustrate the thermal analysis applications of the program.

“As we handle more operations and passengers in the air, we must make certain we have the capacity to handle increased traffic on the ground.” - Jane Garvey, FAA Administrator (4/20/98) The FAA Technical Center (Aviation System Analysis and Modeling Branch, ACT-520) has been responsive to the FAA Airport Capacity Program customers for the past 22 years, developing, testing, and applying airfield and airspace simulation models. More than 90 capacity studies have been completed with ACT-520 personnel contributing their technical expertise to the Airport Design Teams. The teams are comprised of FAA personnel, airport operators, air carriers, other airport users and aviation industry representatives at major airports throughout the US. Initial studies focused on modeling airport operations from final approach, taxi, gate operations and departure processing. Later in the program, local airspace studies were included in some airport study efforts.

A set of physically based retrieval algorithms has been developed to derive from multispectral satellite imagery a variety of cloud properties that can be used to diagnose icing conditions when upper-level clouds are absent. The algorithms are being applied in near-real time to the Geostationary Operational Environmental Satellite (GOES) data over Florida, the Southern Great Plains, and the midwestern USA. The products are available in image and digital formats on the world-wide web. The analysis system is being upgraded to analyze GOES data over the CONUS. Validation, 24-hour processing, and operational issues are discussed.

Natural fliers demonstrate a diverse array of flight capabilities, many of which are poorly understood. NASA has established a research project to explore and exploit flight technologies inspired by biological systems. One part of this project focuses on dynamic modeling and control of micro aerial vehicles that incorporate flexible wing structures inspired by natural fliers such as insects, hummingbirds and bats. With a vast number of potential civil and military applications, micro aerial vehicles represent an emerging sector of the aerospace market. This paper describes an ongoing research activity in which mechanization and control concepts for biologically inspired micro aerial vehicles are being explored. Research activities focusing on a flexible fixed-wing micro aerial vehicle design and a flapping-based micro aerial vehicle concept are presented.

The Federal Aviation Administration (FAA) has recognized that there is a need to establish an orderly path to move Research, Engineering & Development (RE&D) aviation weather products into an operational environment. To address this need, FAA’s Air Traffic System Requirements Service (ARS) established the Aviation Weather Technology Transfer (AWTT) Board with the principal mission to manage and accelerate the transfer of RE&D products into operations. The board is comprised of members that cut across FAA services and includes representation from the National Weather Service (NWS). The board encourages the development of new aviation weather products that improve the depiction and forecasting of weather events that affect not only the safety of the National Airspace System (NAS) but also the efficiency. This paper describes how the board manages this technology transfer process and how it decides whether a product is acceptable for experimental evaluation or operations.

One goal of space radiation research is to reduce the computational time and increase the accuracy of various radiation calculations to aid in their use in a collaborative engineering environment. For example, a fast turn around time is a feature needed for comparison of radiation shielding effects associated with various design configurations of the International Space Station. Research toward this effort has been conducted on various forms of the low energy neutron Boltzmann equation. Simplified models involving the straight ahead approximation, which have fast computational speeds, have been developed at NASA Langley Research Center during the late 1980's as part of a larger high energy ion transport code. Various modifications to improve the accuracy of these computer codes have been an ongoing project. The goal to increase the accuracy of low energy neutron transport without effecting the fast computational times has been a successful ongoing research effort.

An experimental investigation was conducted to study the effectiveness of Synthetic Vision Systems (SVS) flight displays as a means of eliminating Low Visibility Loss of Control (LVLOC) and Controlled Flight Into Terrain (CFIT) accidents by low time general aviation (GA) pilots. A series of basic maneuvers were performed by 18 subject pilots during transition from Visual Meteorological Conditions (VMC) to Instrument Meteorological Conditions (IMC), with continued flight into IMC, employing a fixed-based flight simulator. A total of three display concepts were employed for this evaluation. One display concept, referred to as the Attitude Indicator (AI) replicated instrumentation common in today's General Aviation (GA) aircraft. The second display concept, referred to as the Electronic Attitude Indicator (EAI), featured an enlarged attitude indicator that was more representative of a “glass display” that also included advanced flight symbology, such as a velocity vector.

The effect on general aviation (GA) pilots' abilities to fly a small airplane while using a prototype data-linked weather information system (WIS) display, located in various cockpit positions, was investigated in comparison to the effect on their flying of acquiring weather information through conventional means. Ten GA pilots performed en route flying tasks of varying difficulty while concurrently performing weather information acquisition tasks. Pilots' subjective workload ratings, weather information acquisition times and accuracy levels, and preliminary flight path parameter deviation data indicate that using a WIS display results in smaller flight path parameter deviations, lower workload, and faster and slightly more accurate information retrieval than when weather information is obtained via the radio.

Pressure Sensitive Paint (PSP) has been used for several years by the aircraft industry in transonic wind tunnel testing where the oxygen concentrations are low and the luminescence of the paint is easily recorded. Extending PSP to slower speeds where the oxygen concentrations are closer to atmospheric conditions is much more challenging. For the past few years, work has been underway at both Wright Patterson Air Force Base and Ford Motor Company to advance PSP techniques for testing at slower speeds. The CRADA (Cooperative Research and Development Agreement) provided a way for comparisons to be made of the different PSP systems that were being investigated. This paper will report on PSP tests conducted as part of the CRADA.

The General Aviation Element of the Aviation Safety Program's Synthetic Vision Systems (SVS) Project is developing technology to eliminate low visibility induced General Aviation (GA) accidents. SVS displays present computer generated 3-dimensional imagery of the surrounding terrain on the Primary Flight Display (PFD) to greatly enhance pilot's situation awareness (SA), reducing or eliminating Controlled Flight into Terrain, as well as Low-Visibility Loss of Control accidents. SVS-conducted research is facilitating development of display concepts that provide the pilot with an unobstructed view of the outside terrain, regardless of weather conditions and time of day. A critical component of SVS displays is the appropriate presentation of terrain to the pilot. An experimental study is being conducted at NASA Langley Research Center (LaRC) to explore and quantify the relationship between the realism of the terrain presentation and resulting enhancements of pilot SA and performance.

A 10-foot-long fuselage section from a Boeing 737-100 airplane was dropped from a height of 14 feet generating a final impact velocity of 30 feet per second. The fuselage section was configured to simulate the load density at the maximum takeoff weight condition. The final weight of 8870 pounds included cabin seats, dummy occupants, overhead stowage bins with contents, and cargo compartment luggage. The fuselage section was instrumented with strain gages, accelerometers, and high-speed cameras. The fuselage sustained severe deformation of the cargo compartment. The luggage influenced the manner in which the fuselage crushed, affecting the gravitational (g) forces experienced by the test section. The seat tracks experienced 15 g's vertical deceleration. Although numerous fuselage structural members fractured during the test, a habitable environment was maintained for the occupants, and the impact was considered survivable.

Recently, there has been a strong emphasis on aerodynamic and aeroacoustic wind tunnel testing of automobiles. While significant level resources have been spent on investigating aerodynamics, the methodology has not changed appreciably since the beginning of aerodynamics as a science. Over the past decade, a number of global flow diagnostic techniques have been developed that drastically increase the quality and quantity of data from wind tunnel testing. One of these technologies is the use of pressure sensitive luminescent coatings, known as pressure-sensitive paint, a method which has matured considerably since its inception and is now used extensively in aerospace applications with good results. The goal of this research is to implement this technology in the full scale testing of high performance automotive vehicles. This paper discusses the details of a preliminary test, such as technique, paint formulation, camera and lighting hardware, and data reduction and analysis.