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At least 19 records

NACA Conference on aerodynamics of high-speed aircraft

This document contains unedited reproductions of technical papers on some of the most recent research results on the aerodynamics of high-speed aircraft from the NACA Laboratories. These papers were presented by members of the staff of the NACA Laboratories at the NACA Conference held at the Ames Aeronautical Laboratory July 8-10, 1953. The primary purpose of this conference was to convey to contractors of the military services and others concerned with the design of aircraft these recent research results and to provide those attending an opportunity to discuss the results.

Source record↗

NACA Conference on High-speed Aerodynamics. a Compilation of Papers Presented

This document contains reproductions of technical papers presented by staff members of the NACA Laboratories at the NACA Conference on High-Speed Aerodynamics held at the Ames Aeronautical Laboratory of the NACA, March 18, 19, and 20, 1958. The primary purpose of the conference was to convey to the military services and their contractors the results of recent research and to provide those attending with an opportunity to discuss the results.

Source record↗

Flight Measurements of the Directional Stability and Control of a P-51D Airplane with a Horn-Balanced Rudder as Compared with Previously Tested Vertical-Tail Configurations

At the request of the Air Materiel Command, Army Air Forces, flight tests were conducted on a P-5lD-20-NA (AAF No. 44-63826) airplane equipped with a horn-balanced rudder. This rudder was fitted with an unbalancing tab as was the original product fan rudder. Tests were made both with the unbalancing tab in operation and with the unbalancing tab locked. The modification to the original vertical tail consisted of removing the cap from the top of the fin and adding 1.91 square feet of area to the rudder as the horn balance and 0.82 square foot of area to the top of the rudder aft of the hinge line. A comparison of the directional stability and control characteristics of the P-51D airplane with three different vertical-tail configurations - the horn balance, original production, and extended tail (with unbalancing tab locked) configurations are presented herein. The tests of the horn-balanced rudder were conducted at the Langley Laboratory in 1945. The tests of the original-tail configuration were previously conducted at the Ames Aeronautical Laboratory. Tests of the extended-tail configuration were conducted at the Langley Laboratory and are reported.

Mungall, Robert G.↗

The History of the XV-15 Tilt Rotor Research Aircraft: From Concept to Flight

This monograph is a testament to the efforts of many people overcoming multiple technical challenges encountered while developing the XV-15 tilt rotor research aircraft. The Ames involvement with the tilt rotor aircraft began in 1957 with investigations of the performance and dynamic behavior of the Bell XV-3 tilt rotor aircraft. At that time, Ames Research Center was known as the Ames Aeronautical Laboratory of the National Advisory Committee for Aeronautics (NACA). As we approach the new millennium, and after more than 40 years of effort and the successful completion of our initial goals, it is appropriate to reflect on the technical accomplishments and consider the future applications of this unique aircraft class, the tilt rotor. The talented engineers, technicians, managers, and leaders at Ames have worked hard with their counterparts in the U.S. rotorcraft industry to overcome technology barriers and to make the military and civil tilt rotor aircraft safer, environmentally acceptable, and more efficient. The tilt rotor aircraft combines the advantages of vertical takeoff and landing capabilities, inherent to the helicopter, with the forward speed and range of a fixed wing turboprop airplane. Our studies have shown that this new vehicle type can provide the aviation transportation industry with the flexibility for highspeed, long-range flight, coupled with runway-independent operations, thus having a significant potential to relieve airport congestion. We see the tilt rotor aircraft as an element of the solution to this growing air transport problem.

Maisel, Martin D.↗

Development of a high-velocity free-flight launcher : the Ames light-gas gun

Recent interest in long-range missiles has stimulated a search for new experimental techniques which can reproduce in the laboratory the high temperatures and Mach numbers associated with the missiles' flight. One promising possibility lies in free-flight testing of laboratory models which are flown at the full velocity of the missile. In this type of test, temperatures are approximated and aerodynamic heating of the model is representative of that experienced by the missile in high-velocity flight. A prime requirement of the free-flight test technique is a device which had the capacity for launching models at the velocities desired. In response to thie need, a gun firing light models at velocities up to 15,000 feet per second has been developed at the Ames Aeronautical Laboratory. The design of this gun, the analysis of its performance, and the results of the initial firing trials are described in this paper. The firing trials showed that the measured velocities and pressures agreed well with the predicted values. Also, the erosion of the launch tube was very small for the eleven rounds fired. The performance of the gun suggests that it will prove to be a satisfactory launcher for high-velocity free-flight tests. However, it should be mentioned that only the gross performance has been evaluated so far, and, consequently, the operation of the gun must be investigated in further detail before its performance can be reliably predicted over its full operating range.

Charters, A C↗

Effect of Mach and Reynolds Numbers on Maximum Lift Coefficient

A knowledge of the effects of Mach and Reynolds numbers on the maximum lift coefficient is becoming of greater importance as the speeds and altitudes attainable by modern airplanes continually increase. Since most maximum-lift tests conducted to date have been either at full-scale Reynolds numbers and low Mach numbers or at high Mach numbers and small Reynolds numbers, very little is known about the inter-related effects of these two parameters on the maximum lift coefficient. In order to obtain quantitative information on these effects, flight tests were conducted at Ames Aeronautical Laboratory on six airplanes, three having NACA conventional airfoil sections, two having NACA low-drag sections, and the sixth having a North American Aviation - NACA compromise low-drag section. The results of these tests which cover a range of Mach numbers from 0.15 to 0.72 and of Reynolds numbers from 4,400,000 to 19,500,000 are assembled, together with a considerable quantity of pertinent wind-tunnel data, and analyzed in the present report. From this analysis, general conclusions have been reached indicating the manner in which the maximum lift coefficient is influenced by variations of Mach and Reynolds numbers.

AIRPLANES - BELL P-63A (AMER ) FLIGHT TESTS↗

Pressure Lag in Tubing Used in Flight Research

Tests described in this report were undertaken to obtain a quantitative measure of the pressure lag in typical pressure-tubing systems used by the Ames Aeronautical Laboratory in flight research investigations. Lag measurements were made with both single-direction and oscillating pressure changes. Single-direction pressure changes were investigated to determine if the lag in orifice-pressure lines and in the research airspeed and altitude measuring systems of pursuit-type airplane undergoing flight tests was sufficient to cause an appreciable error in the record of a sudden pressure change. Oscillating pressure changes were investigated with particular reference to the accuracy of pressure peaks in pressure-distribution measurements during the time of buffeting conditions as found in stalls. (author)

Turner, Howard L↗

Correlation of the Drag Characteristics of a Typical Pursuit Airplane Obtained from High-Speed Wind-Tunnel and Flight Tests

In order to obtain a correlation of drag data from wind-tunnel and flight tests at high Mach numbers, a typical pursuit airplane, with the propeller removed, was tested in flight at Mach numbers up to 0.755, and the results were compared with wind-tunnel tests of a 1/3-scale model of the airplane. The tests results show that the drag characteristics of the test airplane can be predicted with satisfactory accuracy from tests in the Ames 16-foot high-speed wind tunnel of the Ames Aeronautical Laboratory at both high and low Mach numbers. It is considered that this result is not unique with the airplane.

Nissen, James M↗

Investigation of Diving Moments of a Pursuit Airplane in the Ames 16-Foot High Speed Wind Tunnel

A pursuit type airplane encountered severe diving moments in high-speed dives which make recovery difficult. For the purpose of investigating these diving moments and finding means for their reduction, a 1/6-scale model of the airplane was tested in the 16-foot high-speed wind tunnel at Ames Aeronautical Laboratory. The test results indicate that up to a Mach number of at least 0.75, the limit of the tests, the dive-recovery difficulties can be alleviated and the longitudinal maneuverability improved by the substitution of a long symmetrical fuselage for the standard fuselage.

MACH NUMBER↗

High-Speed Wind-Tunnel Tests of a Twin-Fuselage Pursuit Airplane

At the request of the Air Technical Service Command, U.S. Army Air Forces, a 0.22-scale model of a twin-fuselae pursuit airplane was built and tested at the Ames Aeronautical Laboratory. The tests of this model were made in order that the aerodynamic characteristics of the airplane, especially at high speed, might be predicted. The results shown in this report consist of force data for the model and critical Mach numbers of parts of the model as determined from pressure-distribution measurements. The results indicate that a diving tendency of the airplane can be expected at Mach numbers above 0.70 at lift co-efficients from 0 to 0.4. There is an indication that the Mach number at which the airpolane would first experience a diving tendency for lift coefficients from 0 to 0.2 can be increased if the critical speed of the radiator enclosures is increased, and the wing-fuselage-juncture fillets are improved.

WIND TUNNEL TESTS(AAL-HIGH-SPEED-16')(AMER )↗

Considerations involved in the design of a roll-angle computer for a bank-to-turn interceptor

At the Ames Aeronautical Laboratory some flight and analog computer studies have been made on the final attack phase of automatic interceptions. The ultimate objective of these studies is to define the behavior of various types of automatic control systems as influenced by a wide range of aerodynamic characteristics. This is a continuing program still in its initial stages; however, it is felt that conclusions of general significance can be drawn from these preliminary studies. One point of particular importance is the necessity for including a gain charger or computer in the azimuth loop of any bank-to-turn airplane or missile. This device translates azimuth error signals into appropriate roll commands. The results to date have shown that the characteristics of this component have a predominant effect on the behavior of a automatic system. It is the purpose of this paper to discuss considerations of importance in the design of a suitable roll-angle computer. In this regard, the present paper complements the analytical work reported in NACA RM L54E27, 1954.

Triplett, William C↗

Effects of Direction of Propeller Rotation on the Longitudinal Stability of the 1/10-Scale Model of the North American XB-28 Airplane with Flaps Neutral, Special Report

The effects of direction of propeller rotation on factors affecting the longitudinal stability of the XB-28 airplane were measured on a 1/10-scale model in the 7- by 10-foot tunnel of the Ames Aeronautical Laboratory. The main effect observed was that caused by regions of high downwash behind the nacelles (power off as well as power on with flaps neutral). The optimum direction of propeller rotation, both propellers rotating up toward the fuselage, shifted this region off the horizontal tail and thus removed its destabilizing effect. Rotating both propellers downward toward the fuselage moved it inboard on the tail and accentuated the effect, while rotating both propellers right hand had an intermediate result. Comparisons are made of the tail effects as measured by force tests with those predicted from the point-by-point downwash and velocity surveys in the region of the tail. These surveys in turn are compared with the results predicted from available theory.

Delany, Noel K.↗

Construction of Unitary Plan Wind Tunnel

Construction of the unitary plan wind tunnel for the Ames Aeronautical Laboratory in Moffett Field, California. Beginning construction in 1950-51 and completing in 1955. Video shows the building of all stages of construction from the foundation to full completion and view of final building set up. Video should be download and viewed for best results and has run time of 7:07 with color but no sound.

UPWT Wind Tunnel Division↗

NASA in Silicon Valley

Whether looking back only a few years or more than a century, our world has been changing. Communication networks are more widespread and interconnected than at any other time in human history. Computing power that was only imagined a generation ago is now widely available and can fit in the palm of a hand. The miniaturization of the integrated circuit has brought us close to the limit of what is possible with silicon as we explore new possibilities in the quantum realm. For over 80 years, NASA’s Ames Research Center in California’s Silicon Valley has held a special place amidst such change. With change, there also is continuity. Since 1939, Ames contributions have fundamentally shaped fields of study related to aeronautics and space. The ingenuity and problem-solving capabilities of personnel at Ames have affected all our lives in numerous ways, from everyday air travel to how we envision the possibility of life on other worlds. This publication is a mere hint at the rich history of Ames, told primarily through images that capture some of the recurring threads that have intertwined over that time. A bibliography points the reader to more detailed histories of Ames published over the years. They are excellent resources and, like all historical work, unavoidably incomplete. Our standing invitation in the present is to preserve what we can to help us understand where we are and how we arrived.

History↗

Information for Lateral Aircraft Spacing Enabling Closely-Spaced Runway Operations During Instrument-Weather Conditions

In an effort to increase airport capacity, the U.S. plans on investing nearly $6 billion a year to properly maintain and improve the nation's major airports. Current FAA standards however, require a reduction in terminal operations during instrument-weather conditions at many airports, causing delays and reducing airport capacity. NASA, in cooperation with the FAA, has developed the Terminal Area Productivity Program to achieve clear-weather capacity in instrument- weather conditions for all phases of flight. This paper describes a series of experiments planned to investigate the conceptual design of different systems that provide information to flight crews regarding nearby traffic during the approach phase of flight. The purpose of this investigation is to identify and evaluate different display and auditory interfaces to the crew for use in closely-spaced parallel runway operations. Three separate experiments are planned for the investigation. The first two experiments will be conducted using part-task flight simulators located at the MIT Aeronautical Systems Laboratory and at NASA Ames. The third experiment will be conducted in the Advanced Concepts Flight Simulator, a generic "glass-cockpit" simulator at NASA Ames. Subjects for each experiment will be current glass-cockpit pilots from major U.S. air carriers. Subject crews will fly several experimental scenarios in which pseudo-aircraft are "blundered" into the subject aircraft simulation. Runway spacing, longitudinal aircraft separation, aircraft performance and traffic information will be varied. Analyses of the subject reaction times in evading the blundering aircraft and the resulting closest points of approach will be conducted. This paper presents a preliminary examination of the data recorded during the part-task experiments. The impact of traffic information on closely-spaced parallel runway operations is discussed, cockpit displays to aid these operations are examined, and topics for future research are suggested.

Thrush, Trent↗

Integrated Technology Rotor/Flight Research Rotor (ITR/FRR) concept definition study

Studies were conducted by Hughes Helicopters, Inc. (HHI) for the Applied Technology Laboratory and Aeromechanics Laboratory, U.S. Army Research and Technology Laboratories (AVRADCOM) and the Ames Research Center, National Aeronautics and Space Administration (NASA). Results of predesign studies of advanced main rotor hubs, including bearingless designs, are presented in this report. In addition, the Government's rotor design goals and specifications were reviewed and evaluated. Hub concepts were designed and qualitatively evaluated in order to select the two most promising concepts for further development. Various flexure designs, control systems, and pitchcase designs were investigated during the initial phases of this study. The two designs selected for additional development were designated the V-strap and flat-strap cruciform hubs. These hubs were designed for a four bladed rotor and were sized for 18,400 pounds gross weight with the same diameter (62 feet) and solidity (23 inch chord) as the existing rotor on the Rotor Systems Research Aircraft (RSRA).

Hughes, C. W.↗

Trajectory Assessment and Modification Tools for Next Generation Air Traffic Management Operations

This paper reviews three Next Generation Air Transportation System (NextGen) based high fidelity air traffic control human-in-the-loop (HITL) simulations, with a focus on the expected requirement of enhanced automated trajectory assessment and modification tools to support future air traffic flow management (ATFM) planning positions. The simulations were conducted at the National Aeronautics and Space Administration (NASA) Ames Research Centers Airspace Operations Laboratory (AOL) in 2009 and 2010. The test airspace for all three simulations assumed the mid-term NextGenEn-Route high altitude environment utilizing high altitude sectors from the Kansas City and Memphis Air Route Traffic Control Centers. Trajectory assessment, modification and coordination decision support tools were developed at the AOL in order to perform future ATFM tasks. Overall tool usage results and user acceptability ratings were collected across three areas of NextGen operatoins to evaluate the tools. In addition to the usefulness and usability feedback, feasibility issues, benefits, and future requirements were also addressed. Overall, the tool sets were rated very useful and usable, and many elements of the tools received high scores and were used frequently and successfully. Tool utilization results in all three HITLs showed both user and system benefits including better airspace throughput, reduced controller workload, and highly effective communication protocols in both full Data Comm and mixed-equipage environments.

Brasil, Connie↗

A Validated Task Analysis of the Single Pilot Operations Concept

The current day flight deck operational environment consists of a two-person Captain/First Officer crew. A concept of operations (ConOps) to reduce the commercial cockpit to a single pilot from the current two pilot crew is termed Single Pilot Operations (SPO). This concept has been under study by researchers in the Flight Deck Display Research Laboratory (FDDRL) at the National Aeronautics and Space Administration's (NASA) Ames (Johnson, Comerford, Lachter, Battiste, Feary, and Mogford, 2012) and researchers from Langley Research Centers (Schutte et al., 2007). Transitioning from a two pilot crew to a single pilot crew will undoubtedly require changes in operational procedures, crew coordination, use of automation, and in how the roles and responsibilities of the flight deck and ATC are conceptualized in order to maintain the high levels of safety expected of the US National Airspace System. These modifications will affect the roles and the subsequent tasks that are required of the various operators in the NextGen environment. The current report outlines the process taken to identify and document the tasks required by the crew according to a number of operational scenarios studied by the FDDRL between the years 2012-2014. A baseline task decomposition has been refined to represent the tasks consistent with a new set of entities, tasks, roles, and responsibilities being explored by the FDDRL as the move is made towards SPO. Information from Subject Matter Expert interviews, participation in FDDRL experimental design meetings, and study observation was used to populate and refine task sets that were developed as part of the SPO task analyses. The task analysis is based upon the proposed ConOps for the third FDDRL SPO study. This experiment possessed nine different entities operating in six scenarios using a variety of SPO-related automation and procedural activities required to guide safe and efficient aircraft operations. The task analysis presents the roles and responsibilities in a manner that can facilitate testing future scenarios. Measures of task count and workload were defined and analyzed to assess the impact of transitioning to a SPO environment.

task analysis↗