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A new flight research vehicle, the Rotorcraft-Aircrew Systems Concepts Airborne Laboratory (RASCAL), is being developed by the U.S. Army and NASA at Ames Research Center. The requirements for this new facility stem from a perception of rotorcraft system technology requirements for the next decade together with operational experience with the Boeing Vertol CH-47B research helicopter that was operated as an in-flight simulator at Ames during the past 10 years. Accordingly, both the principal design features of the CH-47B variable-stability system and the flight-control and cockpit-display programs that were conducted using this aircraft at Ames are reviewed. Another U.S. Army helicopter, a Sikorsky UH-60A Black Hawk, has been selected as the baseline vehicle for the RASCAL. The research programs that influence the design of the RASCAL are summarized, and the resultant requirements for the RASCAL research system are described.

The effectiveness of an aerodynamic boattail on a tractor/trailer road vehicle was measured in the NASA Ames Research Center 80- by 120- Foot Wind Tunnel. Results are examined for the tractor/trailer with and without the drag reduction device. Pressure measurements and flow visualization show that the aerodynamic boattail traps a vortex or eddy in the corner formed between the device and the rear corner of the trailer. This recirculating flow turns the flow inward as it separates from the edges of the base of the trailer. This modified flow behavior increases the pressure acting over the base area of the truck, thereby reducing the net aerodynamic drag of the vehicle. Drag measurements and pressure distributions in the region of the boattail device are presented for selected configurations. The optimum configuration reduces the overall drag of the tractor/trailer combination by about 10 % at a zero yaw angle.

The facilities being planned for animal research on Space Station Freedom are considered in the context of the development of animal habitats from early ballistic and orbital flights to long-term missions aimed at more detailed scientific studies of the effects of space conditions on the vertebrate organism. Animal habitats are becoming more elaborate, requiring systems for environmental control, waste management, physiological monitoring, as well as ancillary facilities such as a 1-G control centrifuge and a glovebox. Habitats in use or to be used in various types of manned and unmanned spacecraft, and particularly those planned for Space Station Freedom, are described. The characteristics of the habitats are compared with each other and with current standards for animal holding facilities on the ground.

The Space Station Freedom will provide a wealth of new opportunities for life sciences research in the microgravity environment of Earth orbit. Such research will require the long-term housing of plant and animal subjects, as well as cell and tissue culture support systems. In addition to newly designed plant and animal vivaria for micro-g, housing for control subjects at one g and fractional g will be required to provide scientific controls, support gravity threshold studies, and perform experiments at Lunar and Mars gravity levels. A natural adjunct to a set of microgravity vivaria in space is, therefore, a centrifuge which could expose the same specimens to variable gravity levels. The larger the centrifuge, the more subjects that can be housed, the smaller the gravity gradient on the subjects, and the smaller the Coriolis effects. Early studies recommended a 4.0 meter diameter centrifuge, the largest that could be accommodated in a Shuttle launchable module.

The evolutionary history of life on Earth has occurred under the omnipresent influence of a gravitational force. The exposure to the microgravity environment of space produces an array of biochemical and physiological changes in plants and animals. These changes extend from the cellular to the whole organism level. In order to manipulate gravity as an experimental variable and to separate the effects of weightlessness from the other variables in spaceflight, it is essential to provide a source of gravity in space. The scientific user community was consulted on the potential need and science requirements for a centrifuge to be designed for and flown on Space Station Freedom.

Several studies performed in support of the Space Exploration Initiative have identified the need for development or improvement of new or existing regenerative life support process technologies. In part, the need to develop such technologies is dependent on the quantities of consumables that are required by the mission and hence on mission design. Trade studies will be needed to determine appropriate life support system designs that provide consumables to the crew and support systems and dispose of waste materials that are generated. These studies will require quantitative estimates of consumables and waste stream disposal requirements that support a given mission scenario. The NASA Exploration Programs Office (ExPO) is attempting to define the details and logistics of a design reference mission for the first human return to the Moon. The mission is referred to as the First Lunar Outpost.

Low-speed wind-tunnel tests were performed on a generic forward-swept-wing aircraft model in the 7- by 10-Foot Wind Tunnel (No. 2) at Ames Research Center. The effects of various configurational changes and control-surface deflections on the performance of the model were measured. Six-component force measurements were augmented by flow-visualization photographs, using both surface oil-flow and tufts. It was found that the tendency toward premature root separation on the forward-swept wing could be reduced by use of either canards or leading-edge wing strakes and that differential canard deflections can be used to produce direct side-force control.

Optimal turning climb-out and descent flight-paths from and to runway headings are derived to provide the missing elements of a complete flight-path optimization for minimum fuel consumption. The paths are derived by generating a field of extremals, using the necessary conditions of optimal control. Results show that the speed profiles for straight and turning flight are essentially identical, except for the final horizontal accelerating or decelerating turn. The optimal turns, which require no abrupt maneuvers, could easily be integrated with present climb-cruise-descent fuel-optimization algorithms.

Future aircraft cockpits may be equipped with both collision avoidance systems and cockpit traffic situation displays. This paper summarizes a series of experiments investigating a pilot's ability to make a variety of traffic related decisions with a traffic display. Some of the key findings were: Pilots were not able to accurately judge the future position of an aircraft unless the display contained predictor symbols. Pilots' subjective judgements of threat were inversely proportional to time to closest approach but generally were not sensitive to small changes of other parameters of the encounter. When pilots were asked to make avoidance maneuvers based solely on the traffic display, they began their maneuvers well before a CAS advisory would have been triggered. Provided sufficient time was available, pilots preferred horizontal avoidance maneuvers.

Over the years, a wide variety of aircraft configurations have been flown with varying degrees of success. A brief survey of the handling qualities of canard, tandem wing, and flying wing designs indicates that longitudinal stability and control, lateral/directional stability and control, and stall behavior of these concepts were important factors in achieving pilot acceptance.

Piloted, moving-base simulations have been performed in the evaluation of several VTOL control system concepts during landings on a destroyer in adverse weather conditions. All the systems incorporated attitude control augmentation; most systems incorporated various types of translational control augmentation implemented either through aircraft attitude or, more directly, through the propulsion system (thrust magnitude and deflection). Only one of the control systems failed to provide satisfactory handling qualities in calm seas. Acceptable handling qualities in sea state 6 seem to require a system with control augmentation in all translational degrees of freedom.

Ames Research Center is developing the technology for turbine-powered jet engine simulators so that airframe/propulsion system interactions on V/STOL fighter aircraft and other highly integrated configurations can be studied. This paper describes the status of the compact multimission aircraft propulsion simulator (CMAPS) technology. Three CMAPS units have accumulated a total of 340 hr during approximately 1-1/2 yr of static and wind-tunnel testing. A wind-tunnel test of a twin-engine CMAPS-equipped close-coupled canard-wing V/STOL model configuration with nonaxisymmetric nozzles was recently completed. During this test approximately 140 total hours were logged on two CMAPS units, indicating that the rotating machinery is reliable and that the CMAPS and associated control system provide a usable test tool. However, additional development is required to correct a drive manifold O-ring problem that limits the engine-pressure-ratio (EPR) to approximately 3.5.

Wet oxidation was used to oxidize a spacecraft model waste under different oxidation conditions. The variables studied were pressure, temperature, duration of oxidation, and the use of one homogeneous and three heterogeneous catalysts. Emphasis is placed on the final oxidation state of carbon and nitrogen since these are the two major components of the spacecraft model waste and two important plant nutrients.

The Spacelab Life Sciences 2 mission (SLS-2) is the second in a planned series of dedicated Life Sciences missions utilizing the European Space Agency-provided Spacelab module. The mission, tentatively scheduled for a mid-1992 launch, will comprise a total of eighteen experiments encompassing both human and animal research. Eight of the eighteen experiments will involve animal life sciences research and will be managed by the Space Life Sciences Payloads Office (SLSPO) at NASA's Ames Research Center (ARC). The ARC payload complement of eight experiments will include six which use rodents and two which use primates (squirrel monkeys). SLS-2 provides an opportunity for even more extensive investigations into the effects of weightlessness upon the anatomy and physiology of rodent and primate systems.

Using a generalized simulation model developed for piloted evaluations of short take-off/vertical landing aircraft, an initial fixed-base simulation of a mixed-flow, remote-lift configuration has been completed. Objectives of the simulation were to evaluate the integration of the aircraft's flight and propulsion controls to achieve good flying qualities throughout the low-speed flight envelope; to determine control power used during transition, hover, and vertical landing; and to evaluate the transition flight envelope considering the influence of thrust deflection of the remote-lift component. Pilots’ evaluations indicated that Level 1 flying qualities could be achieved for deceleration to hover in instrument conditions, for airfield landings, and for recovery to a small ship when attitude and velocity stabilization and command augmentation control modes were provided.

The Life Sciences Glovebox will provide the bioisolated environment to support on-orbit operations involving non-human live specimens and samples for human life sciences experiments. It will be part of the Centrifuge Facility, in which animal and plant specimens are housed in bioisolated Habitat modules and transported to the Glovebox as part of the experiment protocols supported by the crew. At the Glovebox, up to two crew members and two Habitat modules must be accommodated to provide flexibility and support optimal operations. This paper will present several innovative design concepts that attempt to satisfy the basic Glovebox requirements. These concepts were evaluated for ergonomics and ease of operations using computer modeling and full-scale mockups. The more promising ideas were presented to scientists and astronauts for their evaluation. Their comments, and the results from other evaluations are presented.

The first step in verifying the design of the rodent Research Animal Holding Facility (RAHF) as a barrier to environmental contaminants was successfully completed at NASA Ames Research Center (ARC) during a 12-day bio-compatibility test. Environmental contaminants considered were solid particulates, microorganisms, ammonia, and odor-producing organics. The 12-day test at ARC was conducted in August 1988, and was designed to verify that the rodent RAHF system would adequately support and maintain animal specimens during normal system operations. Additional objectives of this test were to demonstrate that: 1) typical particulate debris produced by the animal, i.e., feces and food bar crumbs, would be captured by the system; 2) microorganisms would be contained; and 3) the passage of odor-producing organics and ammonia generated by the animals was adequately controlled. In addition, the amount of carbon dioxide exhausted by the RAHF system was to be quantified.

This paper reports the results of a project supported by the National Aeronautics and Space Administration, Office of Aeronautics and Space Technology (NASA-OAST) under the Advanced Life Support Development Program. It is an initial attempt to integrate artificial intelligence techniques (via expert systems) with conventional quantitative modeling tools for advanced physical-chemical life support systems. The addition of artificial intelligence techniques will assist the designer in the definition and simulation of loosely/well-defined life support processes/problems as well as assist in the capture of design knowledge, both quantitative and qualitative. Expert system and conventional modeling tools are integrated to provide a design workstation that assists the engineer/scientist in creating, evaluating, documenting and optimizing physical-chemical life support systems for short-term and extended duration missions.

Takeoff predictions for powered lift short takeoff (STO) aircraft have been added to NASA AMES Research Center's aircraft synthesis (ACSYNT) code. The new computer code predicts the aircraft engine and nozzle settings required to achieve the minimum takeoff roll. As a test case, it predicted takeoff ground rolls and nozzle settings for the YAV-8B Harrier that were close to the actual values. Analysis of takeoff performance for an ejector-augmentor design and a vectoring-nozzle design indicated that ground roll can be decreased, for either configuration, by horizontally moving the rear thrust vector closer to the center of gravity, by increasing the vertical position of the ram drag-vector, or by moving the rear thrust vector farther below the center of gravity.

An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine was designed, fabricated and tested. It was fabricated from commercially available components without emphasis on weight, volume and power requirement optimization. Optimizing these parameters would make this process competitive with other spacecraft water recovery systems. Unlike other phase change systems, this process is based on the catalytic oxidation at elevated temperatures of ammonia and volatile hydrocarbons to innocuous products; therefore, no urine pretreatment is required. The testing program consisted of parametric tests, one month of daily tests, and a continuous run of 165 hours. The recovered water is low in ammonia, hydrocarbons and conductivity and requires only adjustment of its pH to meet drinking water standards.