16 Matching Results

Search Results

Advanced search parameters have been applied.

The elimination of dead center in the controls of airplanes with thick sections

Description: In several instances where control flaps are placed in the trailing edges of thick sections, it has appeared that a dead center (slackness or lack of control) exists about the neutral position. The condition was also experienced in the rudder action of the XB1A observation airplane. Examination of smoke pictures of the airflow around struts and airfoils indicates what may be the cause of the phenomenon. The streamwise airflow about the thick fin does not follow the surface of the rudder, and consequently the rudder can be moved between the boundaries of the intervening turbulent zone without developing an aerodynamic force. In order to alleviate this condition, a modification was designed and built for the XB1A. The modified rudder was intended to remedy the condition by thickening the section sufficiently to fill in the zone of turbulent flow and thus eliminate the dead center. The positive results of flight tests are given.
Date: November 1, 1922
Creator: Carroll, Thomas
Partner: UNT Libraries Government Documents Department

The Effect on Performance of a Cutaway Center Section

Description: "The assumption is made that a skeleton or cutaway center section is desirable for forward vision and to determine the effect of such mutilation upon performance the following work was done. The airplane used was a Vought VE-7 and in addition to the cutaway center section a system of end plates or fins was installed. Various conditions and combinations were investigated in level flight and in climb" (p. 1).
Date: January 1928
Creator: Carroll, Thomas
Partner: UNT Libraries Government Documents Department

A Comparison of the Take-Off and Landing Characteristics of a Number of Service Airplane

Description: "This investigation, which is a continuation of Technical Report 154, follows very closely the earlier methods and covers a number of service airplanes, whereas the previous report covered but one, the JN-4H. In addition to the air speed, acceleration, and control positions as given in report no. 154, information is here given regarding the distance run and the ground speed for the various airplanes during the two maneuvers" (p. 457).
Date: 1927
Creator: Carroll, Thomas
Partner: UNT Libraries Government Documents Department

A Dangerous Seaplane Landing Condition

Description: "A peculiar phenomena in seaplane landing is observed and reported. The seaplane having executed a normal fast landing at low incidence, a forward movement of the control stick effected an unusual condition in that the seaplane left the water suddenly in an abnormal attitude. The observations describing this phenomena are offered as a warning against possible accident and as a conjectural cause of seaplane landing accidents of a certain kind" (p. 1).
Date: May 1928
Creator: Carroll, Thomas
Partner: UNT Libraries Government Documents Department

A warning concerning the take-off with heavy load

Description: "A successful take-off can be made with an airplane so heavily loaded that it cannot climb to a height greater than the span of its wings. The explanation is that the power required to maintain level flight at an altitude of the order of the wing span may be as much as 50 per cent greater than that necessary when the airplane is just clear of the ground. The failure of heavily loaded airplanes to continue climbing at the rate attained immediately after the actual take-off is a grave hazard and has resulted in great risk or catastrophe in three notable cases which are cited" (p. 1).
Date: July 1927
Creator: Reid, Elliott G. & Carroll, Thomas
Partner: UNT Libraries Government Documents Department

The formation of ice upon exposed parts of an airplane in flight

Description: In order to experimentally study the conditions leading to ice formation on aircraft surfaces, an aircraft was equipped with small auxiliary surfaces and aerodynamic shapes similar to struts, wires, Pitot heads, etc. This airplane was flown at an altitude where a temperature of 32 F was encountered, at such times as cloud formations could be found at the coincident altitude. Here it was discovered that ice formed rapidly in regard to quantity,character, shape, and rapidity of formation. An examination of this data, which confirms observations of pilots, indicates that the weight of ice collected can very possibly be sufficient to force the airplane to rapidly lose altitude on account of the increased loads. However, it is more evident that the malformation of the aerodynamic shapes may so increase the drag and reduce the lift so as to produce a loss of altitude even greater in consequence, the combination of the two working in the same direction having a double effect. Other adverse consequences are noted. The recommendation for the guidance of those who must encounter these conditions appears to lie entirely along the lines of avoidance.
Date: July 1, 1928
Creator: Carroll, Thomas & Mcavoy, Wm H
Partner: UNT Libraries Government Documents Department

The use of wheel brakes on airplanes

Description: The results of tests to determine the effect of wheel brakes on the landing run of an airplane under conditions of load and at various wind velocities are presented.
Date: July 1, 1929
Creator: Carroll, Thomas & Defrance, Smith J
Partner: UNT Libraries Government Documents Department

High Altitude Flying

Description: This note investigates the effect of high altitude or low atmospheric pressure upon the operation of an engine and the effect of the low pressure and lack of oxygen and of the very low temperatures upon the pilot and upon the performance of the airplane itself.
Date: May 1924
Creator: King, Paul B. & Carroll, Thomas
Partner: UNT Libraries Government Documents Department

The Formation of Ice Upon Airplanes in Flight

Description: This report describes the atmospheric conditions under which ice is formed upon the exposed parts of airplanes in flight. It identifies the formation found under different conditions, and describes some studies of preventative means.
Date: August 1929
Creator: Carroll, Thomas & McAvoy, William H.
Partner: UNT Libraries Government Documents Department

Spiral Tendency in Blind Flying

Description: "The flight path followed by an airplane which was being flown by a blindfolded pilot was observed and recorded. When the pilot attempted to make a straight-away flight there was a tendency to deviate from the straight path and to take up a spiral one" (p. 1).
Date: August 1929
Creator: Carroll, Thomas & McAvoy, William H.
Partner: UNT Libraries Government Documents Department

Home Area Networks and the Smart Grid

Description: With the wide array of home area network (HAN) options being presented as solutions to smart grid challenges for the home, it is time to compare and contrast their strengths and weaknesses. This white paper examines leading and emerging HAN technologies. The emergence of the smart grid is bringing more networking players into the field. The need for low consistent bandwidth usage differs enough from the traditional information technology world to open the door to new technologies. The predominant players currently consist of a blend of the old and new. Within the wired world Ethernet and HomePlug Green PHY are leading the way with an advantage to HomePlug because it doesn't require installing new wires. In the wireless the realm there are many more competitors but WiFi and ZigBee seem to have the most momentum.
Date: April 1, 2011
Creator: Clements, Samuel L.; Carroll, Thomas E. & Hadley, Mark D.
Partner: UNT Libraries Government Documents Department

Cyber Friendly Fire

Description: Cyber friendly fire (FF) is a new concept that has been brought to the attention of Department of Defense (DoD) stakeholders through two workshops that were planned and conducted by the Air Force Research Laboratory (AFRL) and research conducted for AFRL by the Pacific Northwest National Laboratory. With this previous work in mind, we offer a definition of cyber FF as intentional offensive or defensive cyber/electronic actions intended to protect cyber systems against enemy forces or to attack enemy cyber systems, which unintentionally harms the mission effectiveness of friendly or neutral forces. Just as with combat friendly fire, a fundamental need in avoiding cyber FF is to maintain situation awareness (SA). We suggest that cyber SA concerns knowledge of a system's topology (connectedness and relationships of the nodes in a system), and critical knowledge elements such as the characteristics and vulnerabilities of the components that comprise the system (and that populate the nodes), the nature of the activities or work performed, and the available defensive (and offensive) countermeasures that may be applied to thwart network attacks. A training implication is to raise awareness and understanding of these critical knowledge units; an approach to decision aids and/or visualizations is to focus on supporting these critical knowledge units. To study cyber FF, we developed an unclassified security test range comprising a combination of virtual and physical devices that present a closed network for testing, simulation, and evaluation. This network offers services found on a production network without the associated costs of a real production network. Containing enough detail to appear realistic, this virtual and physical environment can be customized to represent different configurations. For our purposes, the test range was configured to appear as an Internet-connected Managed Service Provider (MSP) offering specialized web applications to the general public. The network is essentially ...
Date: September 1, 2011
Creator: Greitzer, Frank L.; Carroll, Thomas E. & Roberts, Adam D.
Partner: UNT Libraries Government Documents Department

AMI Communication Requirements to Implement Demand-Response: Applicability of Hybrid Spread Spectrum Wireless

Description: While holistically defining the smart grid is a challenge, one area of interest is demand-response. In 2009, the Department of Energy announced over $4 billion in grant and project funding for the Smart Grid. A significant amount of this funding was allotted to utilities for cost sharing projects to deploy Smart Grid technologies, many of whom have deployed and are deploying advanced metering infrastructure (AMI). AMI is an enabler to increase the efficiency of utilities and the bulk power grid. The bulk electrical system is unique in that it produces electricity as it is consumed. Most other industries have a delay between generation and consumption. This aspect of the power grid means that there must be enough generation capacity to meet the highest demand whereas other industries could over produce during off-peak times. This requires significant investment in generation capacity to cover the few days a year of peak consumption. Since bulk electrical storage doesn't yet exist at scale another way to curb the need for new peak period generation is through demand-response; that is to incentivize consumers (demand) to curtail (respond) electrical usage during peak periods. Of the various methods proposed for enabling demand-response, this paper will focus on the communication requirements for creating an energy market using transactional controls. More specifically, the paper will focus on the communication requirements needed to send the peak period notices and receive the response back from the consumers.
Date: September 30, 2011
Creator: Hadley, Mark D.; Clements, Samuel L. & Carroll, Thomas E.
Partner: UNT Libraries Government Documents Department

Towards a Research Agenda for Cyber Friendly Fire

Description: Historical assessments of combat fratricide reveal principal contributing factors in the effects of stress, degradation of skills due to continuous operations or sleep deprivation, poor situation awareness, and lack of training and discipline in offensive/defense response selection. While these problems are typically addressed in R&D focusing on traditional ground-based combat, there is also an emerging need for improving situation awareness and decision making on defensive/offensive response options in the cyber defense arena, where a mistaken response to an actual or perceived cyber attack could lead to destruction or compromise of friendly cyber assets. The purpose of this report is to examine cognitive factors that may affect cyber situation awareness and describe possible research needs to reduce the likelihood and effects of "friendly cyber fire" on cyber defenses, information infrastructures, and data. The approach is to examine concepts and methods that have been described in research applied to the more traditional problem of mitigating the occurrence of combat identification and fratricide. Application domains of interest include cyber security defense against external or internal (insider) threats.
Date: November 18, 2009
Creator: Greitzer, Frank L.; Clements, Samuel L.; Carroll, Thomas E. & Fluckiger, Jerry D.
Partner: UNT Libraries Government Documents Department

Comparison of Routable Control System Security Approaches

Description: This document is an supplement to the 'Secure and Efficient Routable Control Systems.' It addressed security in routable control system communication. The control system environment that monitors and manages the power grid historically has utilized serial communication mechanisms. Leased-line serial communication environments operating at 1200 to 9600 baud rates are common. However, recent trends show that communication media such as fiber, optical carrier 3 (OC-3) speeds, mesh-based high-speed wireless, and the Internet are becoming the media of choice. In addition, a dichotomy has developed between the electrical transmission and distribution environments, with more modern communication infrastructures deployed by transmission utilities. The preceding diagram represents a typical control system. The Communication Links cloud supports all of the communication mechanisms a utility might deploy between the control center and devices in the field. Current methodologies used for security implementations are primarily led by single vendors or standards bodies. However, these entities tend to focus on individual protocols. The result is an environment that contains a mixture of security solutions that may only address some communication protocols at an increasing operational burden for the utility. A single approach is needed that meets operational requirements, is simple to operate, and provides the necessary level of security for all control system communication. The solution should be application independent (e.g., Distributed Network Protocol/Internet Protocol [DNP/IP], International Electrotechnical Commission [IEC] C37.118, Object Linking and Embedding for Process Control [OPC], etc.) and focus on the transport layer. In an ideal setting, a well-designed suite of standards for control system communication will be used for vendor implementation and compliance testing. An expected outcome of this effort is an international standard.
Date: June 1, 2011
Creator: Edgar, Thomas W.; Hadley, Mark D.; Carroll, Thomas E.; Manz, David O. & Winn, Jennifer D.
Partner: UNT Libraries Government Documents Department