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As Investigation at Mach Numbers of 1.41 and 2.01 of the Aerodynamic Characteristics of an 0.025-scale Model of the MX-1712

Description: An investigation of the aerodynamic characteristics of an 0.025-scale model of the MX-1712 configuration has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel. The tests were performed at Mach numbers of 1.41 and 2.01 at a Reynolds number of approximately 2.6 x 10(exp 6) based on the wing mean aerodynamic chord The MX-1712 is a proposed swept-wing, jet-powered supersonic bomber aircraft. The wing is of aspect ratio 3.5, taper ratio 0.2, and thickness ratio 5.5 percent (streamwise) and has 47deg sweep of the quarter-chord line. The longitudinal and lateral force characteristics of the model and various combinations of its components, including several nacelle installations, were investigated. The effects of a modified wing, two horizontal tail positions, and a shortened fuselage were also studied. The results obtained from these investigations are presented in this report. The aerodynamic investigation of this model disclosed no unusual stability characteristics or Mach number effects. The choice of nacelle installations appears to be a major decision, one greatly affecting the performance of the airplane, At M = 1.41 and C(sub L) = 0.1, the buried nacelles increased the drag of the basic model by 9 percent, while the best pod nacelles increased the drag of the basic model by 27 percent.
Date: October 17, 1952
Creator: Smith, Norman F. & Hasel, Lowell E.
Partner: UNT Libraries Government Documents Department

Measurement of static forces on internally carried bombs of three fineness ratios in flow field of a swept-wing fighter-bomber configuration at a Mach number of 1.61 with illustrative drop-path calculations

Description: Report presenting a wind-tunnel investigation of bomb-release problems by measuring static forces for computation of bomb drop paths. Forces and moments were measured on bombs of three fineness ratios and on a swept-wing fighter-bomber airplane for various positions of the bomb under an open bomb bay. The wing of the plane is shown to have a significant effect on the bomb forces before and after the bomb emerged from the bomb bay.
Date: January 10, 1957
Creator: Smith, Norman F. & Carlson, Harry W.
Partner: UNT Libraries Government Documents Department

An investigation of a supersonic aircraft configuration having a tapered wing with circular-arc sections and 40 degree sweepback: force characteristics of the complete configuration and its various components at Mach numbers of 1.40 and 1.59

Description: Report presenting an investigation of a supersonic aircraft configuration and various combinations of its components at a range of Mach numbers. Longitudinal- and lateral-force characteristics of the configurations, as well as longitudinal- and lateral-stability derivatives, are provided.
Date: January 22, 1951
Creator: Smith, Norman F. & Marte, Jack E.
Partner: UNT Libraries Government Documents Department

Development of Characterization Tools for Reliability Testing of MicroElectroMechanical System Actuators

Description: Characterization tools have been developed to study the performance characteristics and reliability of surface micromachined actuators. These tools include (1) the ability to electrically stimulate or stress the actuator, (2) the capability to visually inspect the devices in operation, (3) a method for capturing operational information, and (4) a method to extract performance characteristics from the operational information. Additionally, a novel test structure has been developed to measure electrostatic forces developed by a comb drive actuator.
Date: July 26, 1999
Creator: Allen, James J.; Eaton, William P.; Smith, Norman F. & Tanner, Danelle M.
Partner: UNT Libraries Government Documents Department

The development and application of high-critical-speed nose inlets

Description: An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements. The test results data have been arranged in the form of design charts from NACA 1-series nose-inlet proportions and can be selected for given values of critical Mach number and airflow quantity. Examples of nose-inlet selections are presented for a typical jet-propulsion installation (critical Mach number of 0.83) and for two conventional radial-engine installations (critical Mach number of 0.76).
Date: January 1, 1948
Creator: Baals, Donald D; Smith, Norman F & Wright, John B
Partner: UNT Libraries Government Documents Department

An investigation of a supersonic aircraft configuration having a tapered wing with circular-arc section and 40 degree sweepback: a pressure-distribution study of the aerodynamic characteristics of the wing at Mach number 1.40

Description: Report discussing a pressure-distribution investigation of a wing of a supersonic aircraft in the presence of a fuselage at a specified Mach number and aerodynamic chord. The wing had a quarter chord swept back 40 degrees, an aspect ratio of 4, a taper ratio of 0.5, and 10-percent-thick circular-arc sections perpendicular to the quarter-chord line. The results were compared to a similar investigation at a different Mach number.
Date: April 20, 1951
Creator: Smith, Norman F.; Kainer, Julian H. & Webster, Robert A.
Partner: UNT Libraries Government Documents Department

Microdiagnostic Lab on a Chip - LDRD Final Report

Description: Polycrystalline silicon (polysilicon) surface micromachining is a new technology for building micrometer ({micro}m) scale mechanical devices on silicon wafers using techniques and process tools borrowed from the manufacture of integrated circuits. Sandia National Laboratories has invested a significant effort in demonstrating the viability of polysilicon surface micromachining and has developed the Sandia Ultraplanar Micromachining Technology (SUMMiT V{trademark} ) process, which consists of five structural levels of polysilicon. A major advantage of polysilicon surface micromachining over other micromachining methods is that thousands to millions of thin film mechanical devices can be built on multiple wafers in a single fabrication lot and will operate without post-processing assembly. However, if thin film mechanical or surface properties do not lie within certain tightly set bounds, micromachined devices will fail and yield will be low. This results in high fabrication costs to attain a certain number of working devices. An important factor in determining the yield of devices in this parallel-processing method is the uniformity of these properties across a wafer and from wafer to wafer. No metrology tool exists that can routinely and accurately quantify such properties. Such a tool would enable micromachining process engineers to understand trends and thereby improve yield of micromachined devices. In this LDRD project, we demonstrated the feasibility of and made significant progress towards automatically mapping mechanical and surface properties of thin films across a wafer. The MEMS parametrics measurement team has implemented a subset of this platform, and approximately 30 wafer lots have been characterized. While more remains to be done to achieve routine characterization of all these properties, we have demonstrated the essential technologies. These include: (1) well-understood test structures fabricated side-by-side with MEMS devices, (2) well-developed analysis methods, (3) new metrologies (i.e., long working distance interferometry) and (4) a hardware/software platform that integrates (1), (2) and ...
Date: March 1, 2002
Partner: UNT Libraries Government Documents Department

MEMS reliability in a vibration environment

Description: MicroElectricalMechanical Systems (MEMS) were subjected to a vibration environment that had a peak acceleration of 120g and spanned frequencies from 20 to 2000 Hz. The device chosen for this test was a surface-micromachined microengine because it possesses many elements (springs, gears, rubbing surfaces) that may be susceptible to vibration. The microengines were unpowered during the test. The authors observed 2 vibration-related failures and 3 electrical failures out of 22 microengines tested. Surprisingly, the electrical failures also arose in four microengines in the control group indicating that they were not vibration related. Failure analysis revealed that the electrical failures were due to shorting of stationary comb fingers to the ground plane.
Date: February 3, 2000
Partner: UNT Libraries Government Documents Department

MEMS reliability in shock environments

Description: In order to determine the susceptibility of the MEMS (MicroElectroMechanical Systems) devices to shock, tests were performed using haversine shock pulses with widths of 1 to 0.2 ms in the range from 500g to 40,000g. The authors chose a surface-micromachined microengine because it has all the components needed for evaluation: springs that flex, gears that are anchored, and clamps and spring stops to maintain alignment. The microengines, which were unpowered for the tests, performed quite well at most shock levels with a majority functioning after the impact. Debris from the die edges moved at levels greater than 4,000g causing shorts in the actuators and posing reliability concerns. The coupling agent used to prevent stiction in the MEMS release weakened the die-attach bond, which produced failures at 10,000g and above. At 20,000g the authors began to observe structural damage in some of the thin flexures and 2.5-micron diameter pin joints. The authors observed electrical failures caused by the movement of debris. Additionally, they observed a new failure mode where stationary comb fingers contact the ground plane resulting in electrical shorts. These new failure were observed in the control group indicating that they were not shock related.
Date: February 9, 2000
Partner: UNT Libraries Government Documents Department

MEMS Reliability: Infrastructure, Test Structures, Experiments, and Failure Modes

Description: The burgeoning new technology of Micro-Electro-Mechanical Systems (MEMS) shows great promise in the weapons arena. We can now conceive of micro-gyros, micro-surety systems, and micro-navigators that are extremely small and inexpensive. Do we want to use this new technology in critical applications such as nuclear weapons? This question drove us to understand the reliability and failure mechanisms of silicon surface-micromachined MEMS. Development of a testing infrastructure was a crucial step to perform reliability experiments on MEMS devices and will be reported here. In addition, reliability test structures have been designed and characterized. Many experiments were performed to investigate failure modes and specifically those in different environments (humidity, temperature, shock, vibration, and storage). A predictive reliability model for wear of rubbing surfaces in microengines was developed. The root causes of failure for operating and non-operating MEMS are discussed. The major failure mechanism for operating MEMS was wear of the polysilicon rubbing surfaces. Reliability design rules for future MEMS devices are established.
Date: January 1, 2000
Partner: UNT Libraries Government Documents Department