Magnetic bearings for a high-performance optical disk buffer

An optical disk buffer concept can provide gigabit-per-second data rates and terabit capacity through the use of arrays of solid state lasers applied to a stack of erasable/reusable optical disks. The RCA optical disk buffer has evoked interest by NASA for space applications. The porous graphite air bearings in the rotary spindle as well as those used in the linear translation of the read/write head would be replaced by magnetic bearings or mechanical (ball or roller) bearings. Based upon past experience, roller or ball bearings for the translation stages are not feasible. Unsatisfactory, although limited experience exists with ball bearing spindles also. Magnetic bearings, however, appear ideally suited for both applications. The use of magnetic bearings is advantageous in the optical disk buffer because of the absence of physical contact between the rotating and stationary members. This frictionless operation leads to extended life and reduced drag. The manufacturing tolerances that are required to fabricate magnetic bearings would also be relaxed from those required for precision ball and gas bearings. Since magnetic bearings require no lubricant, they are inherently compatible with a space (vacuum) environment. Magnetic bearings also allow the dynamics of the rotor/bearing system to be altered through the use of active control. This provides the potential for reduced vibration, extended regions of stable operation, and more precise control of position

Design and development of 3D printed fins integrated into an instrumented surfboard

Surfing is a highly competitive sport, to which additive manufacturing technology can be applied to develop new solutions to improve knowledge. The main focus of this study was to design, prototype and test 3D printed surfboard fins with incorporated sensors interfaced with an instrumented surfboard prototype. Specific aim 1 (customisation of a 3D printer in order to 3D print with carbon fibre composites) was addressed by changing the nozzle, extruder, motherboard, stepper drivers, heat bed surface, and introduction of the dry box to the Creality CR-10S 3D printer. Introduced modifications resulted in successful 3D printing using abrasive and hygroscopic filament materials. Specific aim 2 (3D printing of model samples and instrumented fins) was achieved by using a customised 3D printer to fabricate 101 rectangular samples and six instrumented fins. The surfboard fin was designed in CAD and inspired by Futures T1 Twin HC (Futures Fins). Two sensors were incorporated into the fin. The first was 3D printed in-house out of conductive PLA, and TPU filaments while the second one was a commercially obtained 350 Ω full Wheatstone bridge. Specific aim 3 (design, and manufacturing of moulds and tools used for mechanical analysis and data collection unit) was addressed by the development of the so-called pandemic tool, a Shimadzu EZ-S mechanical analyser adapter, touch probe, fin mould, mould for rectangular samples (produced from high-density poly(ethylene) (HDPE) material), and router templates. The comparison between the so-called pandemic tool and the Shimadzu EZ-S laboratory tool showed an excellent accuracy of around 20 % in a range of 0 to around 5 GPa of calculated flexural modulus. The accuracy above 5 GPa was exponentially lower. Specific aim 4 (mechanical analysis of model samples and fins) was achieved using the pandemic tool during Covid-19 pandemic related lockdowns, and the Shimadzu EZ-S between lockdowns. Mechanical analysis of rectangular samples concluded that carbon fibre reinforced Nylon 6 (CF-PA6) with prepreg composite exhibited the highest flexural modulus value (12 ± 1 GPa). The final aim (laboratory and field-testing of instrumented fins) was addressed by laboratory testing of an instrumented fin using a universal mechanical analyser. The results of a tested prototype of an instrumented fin indicated that under tension the commercial Wheatstone bridge exhibited a linear response to applied stroke in a range of up to 7.7 ± 0.1 % of a fin flex. Field-testing was achieved in two trials. The first field test involved driving with a car that had the instrumented surfboard and fins mounted onto it. The second field test involved paddling and walking the instrumented surfboard and fins in a waveless part of the ocean (Gunnamatta Bay, NSW, Australia). The preliminary data results indicate the excellent GPS accuracy of the telemetry unit. Data from sensors installed in the surfboard and fins were saved on the µSD card, while it was simultaneously transferred in real-time between the surfboard’s electronics and the transceiver connected to the laptop with a 13 Hz sampling rate. The main outcome of this project was the development of a working prototype of a surfboard with inbuilt electronics and a set of instrumented fins

Investigation of air transportation technology at Princeton University, 1991-1992

The Air Transportation Research Program at Princeton University proceeded along six avenues during the past year: (1) intelligent flight control; (2) computer-aided control system design; (3) neural networks for flight control; (4) stochastic robustness of flight control systems; (5) microburst hazards to aircraft; and (6) fundamental dynamics of atmospheric flight. This research has resulted in a number of publications, including archival papers and conference papers. An annotated bibliography of publications that appeared between June 1991 and June 1992 appears at the end of this report. The research that these papers describe was supported in whole or in part by the Joint University Program, including work that was completed prior to the reporting period

The F-18 High Alpha Research Vehicle: A High-Angle-of-Attack Testbed Aircraft

The F-18 High Alpha Research Vehicle is the first thrust-vectoring testbed aircraft used to study the aerodynamics and maneuvering available in the poststall flight regime and to provide the data for validating ground prediction techniques. The aircraft includes a flexible research flight control system and full research instrumentation. The capability to control the vehicle at angles of attack up to 70 degrees is also included. This aircraft was modified by adding a pitch and yaw thrust-vectoring system. No significant problems occurred during the envelope expansion phase of the program. This aircraft has demonstrated excellent control in the wing rock region and increased rolling performance at high angles of attack. Initial pilot reports indicate that the increased capability is desirable although some difficulty in judging the size and timing of control inputs was observed. The aircraft, preflight ground testing and envelope expansion flight tests are described

STOLAND

The STOLAND system includes air data, navigation, guidance, flight director (including a throttle flight director on the Augmentor Wing), 3-axis autopilot and autothrottle functions. The 3-axis autopilot and autothrottle control through parallel electric servos on both aircraft and on the augmentor wing, the system also interfaces with three electrohydraulic series actuators which drive the roll control surfaces, elevator and rudder. The system incorporates automatic configuration control of the flaps and nozzles on the augmentor wing and of the flaps on the Twin Otter. Interfaces are also provided to control the wing flap chokes on the Augmentor Wing and the spoilers on the Twin Otter. The STOLAND system has all the capabilities of a conventional integrated avionics system. Aircraft stabilization is provided in pitch, roll and yaw including control wheel steering in pitch and roll. The basic modes include altitude hold and select, indicated airspeed hold and select, flight path angle hold and select, and heading hold and select. The system can couple to TACAN and VOR/DME navaids for conventional radial flying

On the applicability of integrated circuit technology to general aviation orientation estimation

The criteria of the significant value of the panel instruments used in general aviation were examined and kinematic equations were added for comparison. An instrument survey was performed to establish the present state of the art in linear and angular accelerometers, pressure transducers, and magnetometers. A very preliminary evaluation was done of the computers available for data evaluation and estimator mechanization. The mathematical model of a light twin aircraft employed in the evaluation was documented, the results of the sensor survey and the results of the design studies were presented

Aerospace Medicine and Biology. A continuing bibliography (Supplement 226)

This bibliography lists 129 reports, articles, and other documents introduced into the NASA scientific and technical information system in November 1981

Thin-Wall Machining of Light Alloys: A Review of Models and Industrial Approaches

Thin-wall parts are common in the aeronautical sector. However, their machining presents serious challenges such as vibrations and part deflections. To deal with these challenges, di erent approaches have been followed in recent years. This work presents the state of the art of thin-wall light-alloy machining, analyzing the problems related to each type of thin-wall parts, exposing the causes of both instability and deformation through analytical models, summarizing the computational techniques used, and presenting the solutions proposed by di erent authors from an industrial point of view. Finally, some further research lines are proposed

Human factors in space telepresence

The problems of interfacing a human with a teleoperation system, for work in space are discussed. Much of the information presented here is the result of experience gained by the M.I.T. Space Systems Laboratory during the past two years of work on the ARAMIS (Automation, Robotics, and Machine Intelligence Systems) project. Many factors impact the design of the man-machine interface for a teleoperator. The effects of each are described in turn. An annotated bibliography gives the key references that were used. No conclusions are presented as a best design, since much depends on the particular application desired, and the relevant technology is swiftly changing