Originating Technology/NASA Contribution
While many air travelers are accustomed to rules against electronic devices during takeoff and landing, they might not be aware that these devices are banned because they can cause electromagnetic interference (EMI) with navigation equipment. Because similar problems can occur near launch sites for space missions, NASA began investigating technologies for tracking this interference in order to protect sensitive mission instrumentation. This electronic encroachment is partly due to a myriad of modern communication devices in the marketplace, but unfortunately could also be due to intentional and malicious transmissions. Uninterrupted communication between range activities, mission control, and the flight deck is critical to human safety and mission security, so NASA worked with a company that develops custom communication systems to design a system for locating sources of radio interference.
Originating Technology/NASA Contribution
As part of its research to make air travel safer, NASA began collaborating with the Federal Aviation Administration (FAA) in 2005 to develop what are now called surface traffic management systems (STMS). Both agencies have expressed a need to gather and organize data on airport surface operations, the management of all airport vehicle activities on or near runways, including the movement of aircraft, baggage vans, fuel trucks, catering vehicles, security personnel, and any other ground traffic. STMS continuously record data to determine the position of aircraft using a transponder signal, GPS onboard the aircraft, or primary radar. These surface surveillance systems, which report locations every second for thousands of air and ground vehicles, generate massive amounts of data, making gathering and analyzing this information difficult. To record and help analyze airport operations data with the eventual goal of automating airport ground traffic, NASA sought assistance from private industry.
Originating Technology/NASA Contribution
A small pile of PETI-330 resinous powder PETI-330 is the first resin created specifically for high-temperature composites formed with resin transfer molding and resin infusion. Offering processability, toughness, and high-temperature performance, the resin has a low-melt viscosity and, when cured, a high glass transition temperature.
Originating Technology/NASA Contribution
Designers use computational fluid dynamics (CFD) to gain greater understanding of the fluid flow phenomena involved in components being designed. They also use finite element analysis (FEA) as a tool to help gain greater understanding of the structural response of components to loads, stresses and strains, and the prediction of failure modes.
Automated CFD and FEA engineering design has centered on shape optimization, which has been hindered by two major problems: 1) inadequate shape parameterization algorithms, and 2) inadequate algorithms for CFD and FEA grid modification.
Working with software engineers at Stennis Space Center, a NASA commercial partner, Optimal Solutions Software LLC, was able to utilize its revolutionary, one-of-a-kind arbitrary shape deformation (ASD) capability—a major advancement in solving these two aforementioned problems—to optimize the shapes of complex pipe components that transport highly sensitive fluids.
The ASD technology solves the problem of inadequate shape parameterization algorithms by allowing the CFD designers to freely create their own shape parameters, therefore eliminating the restriction of only being able to use the computer-aided design (CAD) parameters.
The problem of inadequate algorithms for CFD grid modification is solved by the fact that the new software performs a smooth volumetric deformation. This eliminates the extremely costly process of having to remesh the grid for every shape change desired. The program can perform a design change in a markedly reduced amount of time, a process that would traditionally involve the designer returning to the CAD model to reshape and then remesh the shapes, something that has been known to take hours, days—even weeks or months—depending upon the size of the model.
Optimal Solutions Software (OSS) LLC, of Provo, Utah, and Idaho Falls, Idaho, creates highly innovative engineering design improvement products to enable engineers to more reliably, creatively, and economically design new products in high-value markets.
The company entered into a Small Business Innovation Research (SBIR) contract with Stennis, under which it extensively used its ASD software to improve pressure loss, velocity, and flow quality in the pipes utilized by NASA. The product is available under the trade name Sculptor.
Because of the funding from the SBIR program and the technical contributions from its NASA counterparts, OSS was able to take the technological know-how and commercial successes gained from this project and effectively commence the next-phase step into the marketplace.
According to Mark Landon, OSS’s president, “We thoroughly enjoyed working with the engineers and scientists at Stennis—they were technically very sound and extremely helpful in every aspect of the success of the project. Additionally, with the technical and funding assistance from this program, OSS was able to create new jobs, our revenue figures and sales have increased, and private investors are looking at us at this time to take us to the next stage on our road
Implementing Sculptor’s ASD technology and optimizer during the Stennis SBIR Phase II test case, OSS demonstrated a steady-state optimized resistance temperature device (RTD), which produced a smaller and more symmetrical wake, resulting in a lower drag coefficient, thus a lower moment at the base of the RTD. Remarkably, because of the aerodynamic drag reduction from the shape optimization, there was a 60 percent reduction in moment at the base of the RTD probe.
With the assistance from programs such as the SBIR program, the company continues to expand its product family and add features so that its customers can create breakthrough designs and realize increased efficiency gains.
Sculptor can be applied to almost any fluid dynamics problem, structural analysis problem, acoustics design, electromagnetic design, or any area where the designer needs to be able to address complex design analysis. The program performs smooth volumetric deformation and can institute design changes in seconds.
OSS has sold a license for Sculptor to Eglin Air Force Base for the design of unmanned aircraft drones and miniature aircraft. The company has also sold a license for the software to the U.S. Navy for use with Combustion Research and Flow Technology Inc., the author of the CRUNCH CFD code, a multi-element, unstructured flow solver for viscous, real gas systems, currently in use for cavitation modeling, turbo machinery applications, and large eddy simulation.
OSS has also teamed with Engineous Software Inc., the author of the iSIGHT optimization software, to subcontract on a Phase I SBIR with Wright-Patterson Air Force Base to use Sculptor to provide the shape deformation and shape matching for fluid structure interaction solutions. Wright-Patterson has also purchased a Sculptor license for application to aircraft shape design.
Since Sculptor can be utilized in any instance where there is fluid (gas or liquid) flowing in, around, or through an object, the applications are nearly countless.
Automotive shapes and parts such as aerodynamics of the body itself, mirrors, internal flow components such as intake manifolds, radiators, exhaust manifolds, cylinders, and air conditioning ducts all benefit from this program.
The motor sports industry is currently a big customer, with many racing teams finding a competitive edge by using Sculptor to reduce drag, improve down forces, improve engine design, and perform other design analyses, such as for brake cooling, basic flow handling, and internal combustion components.
Other sports are showing a deep interest in the Sculptor technology for such activities as golf club design, swimming and boating aerodynamics—even model airplane flight efficiencies.
Also showing great promise for using these tools are other industries such as biomedicine, which can utilize its ability to more quickly predict the effect of shape
(anatomical) changes in the body’s vascular and other bodily systems.
To expand its domestic and worldwide presence, OSS has established a powerful distribution network, which covers North America, all of the European Union, Japan, South Korea, and China.
Sculptor™ is a trademark of Optimal Solutions Software LLC.
Crunch CFD® is a registered trademark of Combustion Research and Flow Technology Inc.
iSIGHT™ is a trademark of Engineous Software Inc.
Originating Technology/NASA Contribution
NASA astronauts plan to return to the Moon as early as 2015 and establish a lunar base, from which 6-month flights to Mars would be launched by 2030. Essential to this plan is the Ares launch vehicle, NASA’s next-generation spacecraft that will, in various iterations, be responsible for transporting all equipment and personnel to the Moon, Mars, and beyond for the foreseeable future.
The Ares launch vehicle is powered by the J-2X propulsion system, with what will be the world’s largest rocket nozzles. One of the conditions that engineers carefully consider in designing rocket nozzles—particularly large ones—is called separation phenomenon, which occurs when outside ambient air is sucked into the nozzle rim by the relatively low pressures of rapidly expanding exhaust gasses. This separation of exhaust gasses from the side-wall imparts large asymmetric transverse loads on the nozzle, deforming the shape and thus perturbing exhaust flow to cause even greater separation. The resulting interaction can potentially crack the nozzle or break actuator arms that control thrust direction.
Side-wall loads are extremely difficult to measure directly, and, until now, techniques were not available for accurately predicting the magnitude and frequency of the loads. NASA researchers studied separation phenomenon in scale-model rocket nozzles, seeking to use measured vibration on these nozzle replicas to calculate the unknown force causing the vibrations. Key to this approach was the creation of a computer model accurately representing the nozzle as well as the test cell.
System-response models developed by LMS International NV were used to calculate side-wall loads on the J-2X nozzles. LMS is a Belgium-based company founded in 1980 with over 30 offices around the world, which acts as an engineering innovation partner for companies in automotive, aerospace, and other advanced manufacturing industries. LMS works with customers to improve process efficiency and product quality by offering a unique combination of virtual simulation software, testing systems, and engineering services.
LMS Virtual.Lab, an integrated suite of simulation software, developed the system-response models based on modal data on nozzle replicas from LMS Test.Lab, a software solution for test-based engineering combining high-speed multichannel data acquisition with a suite of integrated testing, analysis, and report-generation tools. Tests were conducted by the Marshall Space Flight Center Structural Dynamics Test Branch, which uses LMS Test.Lab in modal testing for a wide range of projects.
The close integration between LMS Test.Lab and LMS Virtual.Lab means data is readily available without file conversions, which often fail to fully represent critical data, such as frequency response functions (FRFs). Utilizing test data in combination with modeling and predictive tools in this type of hybrid approach will enable engineers to more accurately determine transverse separation forces and design nozzles to better withstand operational loads. Marshall also uses LMS Test.Lab for ground vibration testing (GVT) of the new vehicles.
Preparations are underway for GVT of the complete Ares I craft to be conducted in 2011 using the dynamic test stand at Marshall. Tests will be performed on the “full stack,” or the complete vehicle, including the first and second stage motors, fuel tanks, and crew capsule. Structural vibrations will be induced using up to six hydraulic or electrodynamic shakers delivering random and sine excitations. LMS Test.Lab can provide engineers with critical test data including FRFs, natural frequencies, damping values, and mode shapes to evaluate how the structure will likely vibrate during liftoff, stage separation, and subsequent phases of the flight.
The LMS SCADAS 260-channel front-end is also one of NASA’s large modal data-acquisition systems. The high channel count enables the modal test measurements in fewer test runs. Measuring multiple functions simultaneously allows them to obtain FRFs as well as associated cross spectrums, auto powers, and time data in parallel instead of having to run separate tests. The modal test team plans to complete the Ares GVT in only three test sets versus up to eight runs needed for comparable tests on the Saturn and shuttle vehicles using a system with far fewer channels.
The team also makes extensive use of LMS PolyMAX software, which automatically highlights resonances and provides consistent results that could otherwise vary due to subjective interpretation. In addition, animated operational deflection shape features show how the structure may bend and twist at various frequencies so engineers have deeper insight into dynamic structural behavior.
LMS is focused on the mission critical performance attributes in key manufacturing industries, including structural integrity, system dynamics, handling, safety, reliability, comfort, and sound quality. From this work, LMS engineers gained knowledge that will help develop tomorrow’s rocket propulsion systems and can also be used for engineering applications in a wide range of other industries. By providing onsite support for tests, the LMS technical support and development staff seize opportunities like the work with NASA to expand their knowledge of tests and dynamics in real-world applications.
As the pool of companies and agencies testing rockets is limited, knowledge related to the execution and optimization of design resulting from such tests is likewise small. Exposure to this data will lead to better modeling and simulation, resulting in better and safer products for the public. This approach of creating system models based on modal test data is useful in research and development studies of similar structures that are difficult to model and whose dynamic behavior is of primary interest. By working with NASA, LMS engineers gained access to uncommon test data to enhance and refine their product to help companies test future processes and designs.
In one recent example of the benefit of amalgamating experiences into an integrated platform, the Spanish division of the European Aeronautic Defence and Space Company, Construcciones Aeronáuticas S.A. (EADS-CASA), also Spain’s leading aeronautical company, implemented LMS Test.Lab and PolyMAX tools to accelerate its ground vibration testing. This aircraft testing process included a series of tests to detect the aircraft resonances as a verification of the aircraft safety and reliability before the first actual test flights. Overall, the LMS Test.Lab GVT solution and the successful deployment and technology transfer project allowed EADS-CASA to realize considerable savings in time and resources on the Airbus A330 Multi-Role Tanker Transport project.
LMS computer simulation and modeling expertise has also been applied to motorcycle safety and stability. Engineers at BMW Motorrad employed LMS DADS mechanical system simulation software to create virtual prototypes of vehicles and mechanical systems. While LMS DADS included a tire model, motorcycle tires can roll up to 50 degrees, creating forces not captured in the conventional model. BMW engineers used the program’s open architecture to write in two subroutines to measure wobble, weave, and kickback. The first subroutine modeled throttle, brake, and handlebar inputs by a virtual rider. The second modeled tires and their interaction with the pavement, including variables for the frame; lower and upper forks; Telelever, a front suspension design unique to BMW motorcycles; front and rear wheels; rear swing arm; and other components. This model proved remarkably accurate in evaluating motorcycle design—engineers consider the simulation results at least as accurate as measurements taken on the test track, but with less invested time and expense. BMW is now able to specify structural design requirements, such as stiffness and mass distribution, which will ensure greater stability and safety of the end product.
Test.Lab®, Virtual.Lab®, SCADAS®, and PolyMAX® are registered trademarks of LMS International NV.
Telelever™ is a trademark of BMW AG Motorrad.
Originating Technology/NASA Contribution
The last 35 years have seen a sea change in the design of trucks on America’s highways, reflecting extensive research into vehicle aerodynamics and fluid dynamics conducted by NASA engineers. Thanks to the ingenuity of a Dryden Flight Research Center researcher bicycling through the California desert and a team of engineers in Virginia, the shape of rigs and recreational vehicles (RVs) today owes as much to the skies as it does the open road.
Bicyclists, motorcyclists, and even pedestrians feel a push and pull of air as large trucks pass. The larger a vehicle is and the faster it moves, the more air it pushes ahead. For a large truck, this can mean a particularly large surface moving a large quantity of air at a high velocity—its blunt face acting like a fast-moving bulldozer, creating a zone of high pressure. The displaced air must go somewhere, spilling around the cab into swirling vortices. The air traveling along the side moves unevenly, adhering and breaking away, and sometimes dissipating into the surrounding air. At the end of the cab or trailer, the opposite effect of the high-pressure zone at the front develops; the airflow is confronted with an abrupt turn that it cannot negotiate, and a low-pressure zone develops.
The high pressure up front, the turbid air alongside and under the vehicle, and the low pressure at the back all combine to generate considerable aerodynamic drag. A study published in Automotive Engineering in August 1975 found that a tractor trailer unit moving at 55 miles per hour displaced as much as 18 tons of air for every mile traveled. In such cases, roughly half of the truck’s horsepower is needed just to overcome aerodynamic drag.
In 1973, Edwin J. Saltzman, Dryden aerospace engineer and bicyclist, noticed the push and pull of large trucks at highway speeds while riding to work. As a tractor trailer overtook him, he first felt the bow wave of air pushing him slightly away from the road and toward the sagebrush; as the truck swept past, its wake had the opposite effect, drawing him toward the road and even causing both rider and bicycle to lean toward the lane. Saltzman mused about ways to mitigate the bow wave and trailing partial vacuum, and resolved to help trucks glide through air instead of push through it, and, in the process, decrease drag and increase fuel efficiency. NASA colleagues at Dryden were working on the effects of drag and wind resistance on different kinds of aircraft and the early space shuttle designs, so they transferred their considerable knowledge to the design of large trucks.
The first formal experiment involved a Ford van retired from delivery duties at Dryden. Mechanics attached an external frame which was then covered with sheet aluminum to give the van flat sides all around and 90-degree angles at all corners. The vehicle looked like an aluminum shoebox on wheels, simulating the cruder motor homes of the period. The Dryden engineers measured the vehicle’s baseline drag and then set about modifying the shape of the van: First rounding the front vertical corners, then the bottom and top edges of the front, then the edges of the aft end, and finally sealing the entire underbody of the van including the wheel wells, with tests run after each modification. Rounding all four front edges yielded a 52-percent drag reduction, while sealing the bottom of the vehicle gained another 7 percent. The engineers estimated the potential gain in fuel economy to be between 15 and 25 percent at highway speeds.
During the following decade, Dryden researchers conducted numerous tests to determine which adjustments in the shape of trucks reduced aerodynamic drag and improved efficiency. The team leased and modified a cab over engine (COE) tractor trailer, the dominant cab design of the time, from a Southern California firm. Modifications included rounding the corners and edges of the box-shaped cab with sheet metal, placing a smooth fairing on the cab’s roof, and extending the sides back to the trailer.
Rounding the vertical corners on the front and rear of the cab reduced drag by 40 percent while decreasing internal volume by only 1.3 percent. Likewise, rounding the vertical and horizontal corners cut drag by 54 percent, with a 3-percent loss of internal volume. Closing the gap between the cab and the trailer realized a significant reduction in drag and 20 to 25 percent less fuel consumption. A second group of tests added a faired underbody and a boat tail, the latter feature resulting in drag reduction of about 15 percent. Assuming annual mileage of 100,000 driven by an independent trucker, these drag reductions would translate to fuel savings of as much as 6,829 gallons per year.
On the other coast from Saltzman and his Dryden team, Dr. John C. Lin and Floyd G. Howard of Langley Research Center with Dr. Gregory V. Selby of Old Dominion University, Norfolk, Virginia, conducted a series of research projects in the late 1980s and early 1990s focusing on controlling drag and the flow of air around a body. One study conducted in 1989, “Turbulent Flow Separation Control,” explored controlling airflow—flow separation—to decrease energy expenditure and weight in airfoils, inlets, and diffusers and improve aircraft control and decrease drag. The study employed vortex generators, aerodynamic surfaces protruding from a body that draw faster moving air to the surface of the vehicle and disrupt the slower moving boundary layer air around a vehicle, the use of which can be traced back to research conducted by the National Advisory Committee for Aeronautics (NASA’s forebear) in the 1950s. The generated vortices “energize” the slower-moving boundary layer and thereby reduce drag and, in aircraft applications, increase lift.
Subsequent studies in 1990 and 1991 continued vortex-generator research with an exploration of various active and passive methods for controlling two-dimensional separated flow. These studies quantified and characterized the behavior and performance of a variety
of large-eddy breakup devices for turbulent flow separation control.
Answering the charge given by the U.S. Congress in the National Aeronautics and Space Act of 1958 to disseminate newfound technologies and discoveries to the public, NASA makes the results of its research and expertise of its scientists and engineers available through a variety of means. Sponsored by the Innovative Partnerships Program, these include published studies, NASA outreach, the Small Business Innovation Research and Small Business Technology Transfer programs, technology transfer offices at each NASA field center, and the Space Alliance Technology Outreach Program (SATOP).
The aerodynamics studies at Dryden have been made publicly available, and Aeroserve Technologies Ltd., of Ottawa, Canada, with its marketing arm, Airtab LLC, in Loveland, Colorado, applied these studies, the aerodynamic work at Langley, and the patented Wheeler vortex generator to the development of the Airtab vortex generator; designed to reduce drag and improve vehicle stability and fuel economy. Of the devices tested, the Wheeler showed the least parasitic drag, and Aeroserve optimized the Wheeler design for ease of installation and application to any vehicle.
The Surface Transportation Assistance Act of 1982 required states to permit trucks with trailers as long as 48 feet on both interstate and intrastate highways; the previous length limit of 55 feet had applied to the tractor and trailer together. As the previous regulation made the COE tractor a dominant choice, owing to its decreased length regardless of aerodynamic or fuel efficiency shortcomings, the new regulations opened the door for a renaissance of the “conventional” cab. While COE designs place the cab directly above the engine, minimizing length and producing a cube-like tractor, conventional truck designs place the engine ahead of the cab. Though longer as a result, a protruding nose offers truck designers an inherently more aerodynamic shape from which to work. In 1982, COE trucks constituted over 65 percent of the market for the Peterbilt Motors Company, with similar numbers for other manufacturers; the cab-over design represented only 1 percent of sales for Peterbilt by 2004.
Streamlined cabs and fairings are now a common sight on our highways, and the once-prominent cab-over design has been abandoned in virtually all applications except small-capacity urban-oriented trucks where length remains a premium. The modifications tried by the engineers at Dryden were adopted by the truck manufacturers, as the same principles the NASA engineers demonstrated with COE trucks applied to conventionals. In addition, the cargo boxes of most delivery trucks today have rounded corners and edges, a direct application of the research conducted at Dryden on the “shoebox.”
Today’s trailers, on the other hand, are little changed from the last few decades. For livestock haulers, a key factor is that individual farmers have been the predominant owners of trailers, and these owners are difficult to convince about the costs of redesign versus the savings of superior aerodynamics. However, more and more livestock trailers are sporting boat-tail designs that ease the flow of air past the end of the trailer and minimize the low-pressure wake. Conventional trailer manufacturers have resisted change more so than others, in part because the aft end of such a trailer needs to be easy to manipulate at loading docks, where the optimal shape for superior aerodynamics—the boat tail—is impractical.
Likewise, the gap between the cab and the trailer can create a significant amount of drag as air swirls in the space between. Two conventional means to address this issue are problematic: Adding side extenders (to decrease the exposed gap) is expensive and might impede maneuverability; moving the fifth wheel forward (to shorten the gap) places more weight on the steering axle—which is legally regulated and limited—and reduces maneuverability while increasing driver effort and wear on steering tires and steering gear.
Addressing both of these dilemmas, Aeroserve’s Airtabs garner the benefits of the airflow found in a boat-tail design with the practicality of a squared-off end for loading and unloading, and see additional applicability smoothing the airflow between cab and trailer. Airtab vortex generators create a controlled vortex to reduce truck and trailer wind resistance and aerodynamic drag. Each Airtab produces two counter-rotating vortices of air, each approximately four to five times the height of the Airtab and several feet in length, that smoothly bridge the gap between tractor and trailer or control airflow past the rear of the vehicle. Airtabs thus allow an operator to set the fifth wheel to the optimum position without incurring extra drag or steering gear wear penalties and gain some of the aerodynamic benefit of side extenders.
At the back of a trailer, box van, or RV, Airtabs radically alter the airflow to reduce drag in two ways: Shifting the airflow pattern from vertical to horizontal to eliminate large eddies, and smoothing the airflow to artificially simulate a tapered rear of the vehicle. In fact, Airtabs have been shown effective on any vehicle with more than a 30-degree slope to the rear; the potential benefits stretch across vehicular applications and could thus benefit a considerable number of vehicles.
Smoothing the airflow results in markedly improved fuel economy without compromise to design utility, and additional benefits have been realized as well. The vortex generation reduces spray; users have reported improved rear and side view in wet or snowy weather, increasing safety and offering a clearer view of surrounding vehicles. Also, because Airtabs alter the airflow around the rear of a vehicle, the accumulation of road grime is reduced, keeping tail lights and reflectors clean and allowing less snow to build up, a significant safety benefit in foul weather. Less accumulation of road grime also means advertising and safety information on the back of a vehicle remains visible.
Perhaps most importantly, drivers of vehicles fitted with Airtabs have reported improved stability and handling and dramatically reduced fishtailing of trailers—an effect where the trailer sways or slides from side to side independent of the tractor, potentially causing catastrophic loss of control—effects that are especially important with the double trailers found in North America and the famous quad-trailer “road trains” in Australia. Increased stability also means that the trailer does not scrub on the sides of the road as much, increasing the life of tires. Drivers also report better handling when being passed in the same direction by other large vehicles.
Cummins Rocky Mountain LLC, a diesel engine and generator wholesale and distribution company in Broomfield, Colorado, recognized these benefits and agreed to promote and sell Airtabs after internal testing and customer feedback indicated that Airtabs brought immediate safety and fuel economy benefits when running equipment at highway speeds. The company noted additional benefits included ease of installation, minimal maintenance, and low price.
As more NASA research and development is adapted and introduced to the market by companies like Aeroserve, the vehicles populating our highways and interstates will likewise continue to evolve. Practical solutions to aerodynamic challenges, exemplified by the Airtab, offer increased stability, safety, and economy to airborne and surface vehicles alike, and NASA is proud to contribute tangible and current benefits to both fields of transport and travel.
Airtab® is a registered trademark of Aeroserve Technologies Ltd.
Originating Technology/NASA Contribution
For over 30 years, NASA and U.S. Army engineers have worked together at Ames Research Center to make rotorcraft fly more quickly, quietly, and safely in all kinds of weather. Development of new technologies for both military and civil helicopters, tiltrotor aircraft, and other advanced rotary-wing aircraft has engaged disparate parties from all corners of the rotorcraft industry, the U.S. Department of Defense, and other government agencies. These programs have focused on all manner of helicopter components:
- Cockpit controls: Cockpit layout and design can profoundly affect the ease or difficulty of piloting a rotorcraft.
- Handling and performance: NASA and Army experts design flight control systems which make helicopters and other rotorcraft easier to fly using a full-motion simulator and actual aircraft.
- Noise: Most rotorcraft noise results from vibrating parts and the interaction of air vortices shed from the tips of the rotors. Researchers use wind tunnels to investigate ways to reduce noise.
- Speed and performance: Airflow around the fuselage and moving rotor blades is very complex. These complexities limit the helicopter’s speed in moving in different directions. Ames researchers use wind tunnels and computers to investigate ways to improve the airflow.
Particularly focused on safe rotorcraft operation, NASA’s Safe All-Weather Flight Operations for Rotorcraft (SAFOR) element of the Rotorcraft Research and Technology Base Program was specifically tasked with improving the safety of civil helicopter operations. SAFOR ran from 1999 through 2002 and focused on improving drive systems technology, flight control and guidance technology, and situational awareness and information display technologies.
The drive systems element sought to reduce the frequency and consequences of main and tail rotor, transmission, drive, clutch, gearbox, and drive system failures by improving reliability of drive systems. The flight control segment included work to reduce the frequency and severity of accidents due to loss of control, high workload, and exceeding vehicle limits. The situational awareness and information displays unit pursued reduced frequency and severity of accidents due to pilot error, inexperience, poor judgment, lack of situational awareness, and inadequate preparation. SAFOR led to many improvements in helicopter design and operation, some of which have already reached the commercial market.
Hoh Aeronautics Inc. (HAI), of Lomita, California, was founded in 1988 and is dedicated to the analysis and development of conventional and advanced flight control systems and displays for fixed and rotary wing aircraft. HAI engineers also evaluate and develop handling qualities criteria, piloted simulations and flight-test programs, and computer-based training programs.
With support and funding from a Phase II NASA Small Business Innovation Research (SBIR) project from Ames, HAI produced a low-cost, lightweight, attitude-command-attitude-hold stability augmentation system (SAS) for use in civil helicopters and unmanned aerial vehicles (UAVs). The primary advantage of the SAS is that, by increasing helicopter stability and allowing hands-free operation of the aircraft, the system helps the pilot to accomplish divided attention tasks. SAS improves helicopter dynamics and enhances safety in low-speed and hovering maneuvers in degraded visual environments, and for Instrument Flight Rules (IFR) operations in forward flight. As opposed to Visual Flight Rules (VFR), IFR operation of the vehicle references only the instruments and Air Traffic Control, allowing operation in conditions that obscure the pilot’s view; most commercial air traffic operates exclusively under IFR.
The prototype helicopter autopilot/stability augmentation system, dubbed HeliSAS, weighed 12 pounds, significantly less than comparable systems, which can weigh over 50 pounds. HeliSAS proved its superior performance in over 160 hours of flight testing and demonstrations in a Robinson R44 Raven helicopter, one of the most popular commercial helicopters and a particular favorite of news broadcasting and police operations. The HeliSAS reduced pilot workload and increased safety by allowing hands-off flight, and as an added bonus, the system cost significantly less than current systems that perform the same functions.
By offering significant stability and control improvements in a low-cost/lightweight system, HeliSAS promises many benefits in space, military, and civilian aviation applications, including:
- mproving the stability of light helicopters at an affordable cost without excessive weight penalty
- Increasing feasibility of low-cost UAVs
- Potentially developing dual-role, low-cost utility helicopter/UAVs, which can be flown with or without a pilot
HAI developed HeliSAS into a superior stability augmentation system for light helicopters. With the push of a button, the HeliSAS converts the R44 Raven from an unstable aircraft with very light stick forces to a highly stable platform with enhanced control feel that provides force feedback to the pilot—in effect, HeliSAS makes the R44 feel like a much larger, more stable helicopter. With the system engaged, it is possible for the pilot to remove his or her hand from the cyclic to fold charts or perform other cockpit duties, and the R44 has been demonstrated to hold attitude indefinitely with the HeliSAS engaged. A full autopilot option has been added, including altitude hold, heading select/hold, VHF Omni-directional Radio Range Localizer (VOR/LOC) track, Instrument Landing System (ILS) track, and Global Positioning System (GPS) steering.
Shawn Coyle, an instructor at the National Test Pilot School, a not-for-profit educational institute incorporated in California, and former Civil Aviation Authority certification pilot in Canada, conducted a flight evaluation of the HeliSAS, and the system has been featured in Helicopter World magazine’s “North American Special Report 2004” (published in the United Kingdom).
Chelton Flight Systems, of Boise, Idaho, negotiated with HAI to develop, market, and manufacture HAI’s HeliSAS autopilot system, and the product is now available as the Chelton HeliSAS Digital Helicopter Autopilot.
HeliSAS™ is a trademark of Hoh Aeronautics Inc.
Originating Technology/NASA Contribution
As increased energy efficiency, and particularly fuel efficiency, becomes a greater concern, hybrid and electric vehicles gain greater prominence in the market. Electric vehicles (EVs), in particular, provide an attractive option as they produce no emissions during operation, isolating any potential emissions and effluents in the manufacturing and energy-generation streams.
The necessary energy stores to support a shift to EVs already exist, as utilities constructed to address peak demands have off-peak surpluses sufficient to charge about 180 million plug-in hybrid or all-electric cars. According to a report from the U.S. Department of Energy’s Pacific Northwest National Laboratory, there is enough excess generating capacity during the night and morning to allow more than 80 percent of today’s vehicles to make the average daily commute solely using this electricity. Effective energy management sees its ultimate realization in the vehicle-to-grid (V2G) concept, in which plug-in hybrid and electric vehicles can be used to balance energy demand and consumption. In a V2G system, millions of automotive batteries could absorb excess power generated, and release it back into the grid at times of insufficient supply. With a several kilowatt-hour storage capacity per vehicle, millions of operational plug-ins could act as a safety net for the power grid, supplying backup power in an outage, with the vehicle owners credited for power returned to the grid. This smoothing of excess and deficiency in the power grid would also help stabilize intermittent sources of energy such as wind power and make them more viable alternatives.
Historically, the primary obstacles to the widespread application of EVs were lack of infrastructure development and a lack of sufficiently robust battery technologies to consistently power vehicles for an extended duration and at performance levels suitable to a modern urban environment. Technology may at last have caught up with the need, and rising petroleum prices are encouraging more and more consumers to consider electric and hybrid vehicles. In addition, a study by the U.S. Department of Transportation has indicated that plug-in cars capable of 50 miles per day would meet the needs of 80 percent of the American driving public, the average daily ommuters.
NASA has taken a keen interest in battery-powered vehicles, and is encouraging their continued development. The “NASA Official Fleet Management Handbook,” regarding the use of alternative fueled vehicles, states: “Ideally, all Centers should have on-site alternative fuel facilities . . . . Centers are encouraged to use NEVs [Neighborhood Electric Vehicles] to fill inventory requirements where feasible.”
Hybrid Technologies Inc., a manufacturer and marketer of lithium-ion battery-EVs, based in Las Vegas, Nevada, and with research and manufacturing facilities in Mooresville, North Carolina, entered into a Space Act Agreement with Kennedy Space Center to determine the utility of lithium-powered fleet vehicles. Under this agreement, the company supplied a fleet of cars for the engineers at Kennedy to test. In return for the engineering expertise supplied by the NASA employees, the Center was given the opportunity to use the zero-emission vehicles for transportation around the Kennedy campus. NASA contributed engineering expertise for the cars’ advanced battery management system, and vehicles selected for use in the Kennedy fleet included the Hybrid PT Cruiser, lithium smart fortwo, and a high-performance all-terrain vehicle.
The vehicles were powered by Ballard Power Systems’ 312V 67 MS electric drive system, which has a 32kW continuous rating and delivers a peak power of 67kW, with torque of 190 Nm (140 lb-ft). Hybrid Technologies selected this motor based on its proven track record and excellent power-to-weight ratio. The electric PT Cruisers have a top speed in excess of 80 miles per hour and a range of 120 miles. Charge time is 6-8 hours with either 110-120 V or 220-240V, and the lithium-ion battery pack has a cycle life of more than 1,500 charges.
In addition to the vehicles supplied to NASA, the company provided a fleet of lithium-ion battery-powered vehicles for use by the U.S. Environmental Protection Agency and the U.S. Navy.
Hybrid Technologies deployed the first all-electric taxi in New York City and has begun demonstrating smart fortwo conversions like the ones used at Kennedy. The company also delivered an additional two PT Cruiser-based electric taxis and an electric Chrysler Town & Country minivan to the city of Sacramento for use by a private para-transit nonprofit organization. Most recently, Hybrid Technologies has produced an EV version of the popular MINI Cooper, which debuted in the December 2007 Sam’s Club catalog. The EV MINI Cooper proudly displays its NASA heritage, sharing the STS-128 designation with an upcoming Space Shuttle Endeavor mission. It boasts a range of 120 miles at 75 miles per hour, and is driven by a 40kW electric motor and powered by a 30kWh battery pack. The appeal of the electric MINI is strong and widespread, and Hybrid Technologies conversions have already attracted celebrity fans.
Also available from Sam’s Club, the 2007 Hybrid Technologies lithium-powered smart fortwo EV (also available as a limited edition STS-118 smart fortwo) has an estimated range of 150 miles, a top speed over 70 mph, and takes only 4 hours to charge at 220 volts. There are two electric motors that can be used in the vehicle, one from Ballard and one from Siemens VDO. The lithium polymer battery pack comes from Kokam America Inc., and the battery management system is Hybrid Technologies’ own. As an introductory offer, Sam’s Club included a behind-the-scenes trip to Kennedy and attendance at a space shuttle launch, with purchase of one of the EVs. When asked about the availability of amenities such as air conditioning and heating, comforts not always incorporated into EV conversions, Richard Griffiths, Strategic Relations for Hybrid Technologies, stated “The [smart fortwo EV] has absolutely every option, every feature that a regular, production smart car has.” Griffiths estimated the extra amenities consume about 5 percent of the vehicle’s battery capacity. “We’re offering the fully electric smart car to Sam’s Club members as it represents the latest in advanced lithium technology . . . . This limited edition STS-118 smart car will be the perfect addition for car collectors or the environmentalist wanting to make a difference by driving a zero emissions vehicle.” In addition to the MINI Cooper and smart fortwo conversions, Hybrid Technologies offers PT Cruiser and Chrysler Crossfire EV conversions.
Even more impressive than its line of conversions, Hybrid Technologies now also offers a series of purpose-built lithium electric vehicles dubbed the LiV series. The LiV series is designed from the ground up at Hybrid Technologies’ Mooresville plant. The LiV Wise is aimed at the urban and commuter environments, and is larger and offers more interior space than the smart car, the conversion of which is called the LiV Dash. Hybrid Technologies has rounded out the LiV line with custom motorcycles, utility vehicles, mobility scooters, bicycles, and even a military vehicle. Hybrid Technologies plans to offer these vehicles to the U.S. market on a wider scale by 2009, and is especially focused on developing a system that will seamlessly integrate LiV Wise cars in small markets by 2009 and mass markets by 2010.
LiV™, Wise™, and Dash™ are trademarks of Hybrid Technologies Inc.
MINI Cooper® is a registered trademark of Bayerische Motoren Werke AG.
PT Cruiser®, Town & Country®, and Crossfire® are registered trademarks of Chrysler Corporation.
smart® and fortwo® are registered trademarks of Daimler AG.
Ice accumulation is a serious safety hazard for aircraft. The presence of ice on airplane surfaces prevents the even flow of air, which increases drag and reduces lift. Ice on wings is especially dangerous during takeoff, when a sheet of ice the thickness of a compact disc can reduce lift by 25 percent or more. Ice accumulated on the tail of an aircraft (a spot often out of the pilot’s sight) can throw off a plane’s balance and force the craft to pitch downward, a phenomenon known as a tail stall.
Advanced rotorcraft airfoils developed by U.S. Army engineers working with NASA’s Langley Research Center were part of the Army’s risk reduction program for the LHX (Light Helicopter Experimental), the forerunner of the Comanche helicopter. The helicopter’s airfoils were designed as part of the Army’s basic research program and were tested in the 6- by 28-inch Transonic Tunnel and the Low-Turbulence Pressure Tunnel at Langley. While these airfoils did not get applied to the Boeing-Sikorsky Comanche rotor, they did advance the state of the art for rotorcraft airfoils.