Design of a Simple Electronic Flutter Simulator

1953 ◽  
Vol 57 (505) ◽  
pp. 29-38 ◽  
Author(s):  
F. Smith ◽  
W. D. T. Hicks
Keyword(s):  
Degrees Of Freedom ◽  
Successful Operation ◽  
Two Degrees Of Freedom ◽  
Six Degrees Of Freedom ◽  
Electronic Simulator

SummaryThis paper describes the construction of a simple electronic simulator for the solution of flutter problems in two degrees of freedom. It was intended as a prototype for a much larger machine to solve problems in six degrees of freedom.Details of the construction and circuits are given, together with some typical solutions obtained on the machine. As a result of the successful operation of this prototype a larger machine in six degrees of freedom has now been built.

Hydrodynamic Evaluation of a Generic Sail Used in an Innovative Prawn-Trawl Otter Board

2015 ◽  
Author(s):  
Cheslav Balash ◽  
David Sterling ◽  
Matt Broadhurst ◽  
Arno Dubois ◽  
Morgan Behrel
Keyword(s):  
Degrees Of Freedom ◽  
Design Feature ◽  
Hydrodynamic Characteristics ◽  
Flat Plates ◽  
Successful Operation ◽  
Six Degrees Of Freedom ◽  
Recent Innovation ◽  
Hydrodynamic Evaluation ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In prawn-trawling operations, otter boards provide the horizontal force required to maintain net openings, and are typically low aspect ratio (∼0.5) flat plates operating on the seabed at high angles of attack (AOA; 35–40°). Such characteristics cause otter boards to account for up to 30% of the total trawling resistance, including that from the vessel. A recent innovation is the batwing otter board, which is designed to spread trawls with substantially less towing resistance and benthic impacts. A key design feature is the use of a sail, instead of a flat plate, as the hydrodynamic foil. The superior drag and benthic performance of the batwing is achieved by (i) successful operation at an AOA of ∼20° and (ii) having the heavy sea floor contact shoe in line with the direction of tow. This study investigated the hydrodynamic characteristics of a generic sail by varying its twist and camber, to identify optimal settings for maximum spreading efficiency and stability. Loads in six degrees of freedom were measured at AOAs between 0 and 40° in a flume tank at a constant flow velocity, and with five combinations of twist and camber. The results showed that for the studied sail, the design AOA (20°) provides a suitable compromise between greater efficiency (occurring at lower AOAs) and greater effectiveness (occurring at higher AOAs). At optimum settings (20°, medium camber and twist), a lift-to-drag ratio >3 was achieved, which is ∼3 times more than that of contemporary prawn-trawling otter boards. Such a result implies relative drag reductions of 10–20% for trawling systems, depending on the rig configuration.

An Experiment for the Study of Free-Flying Supercavitating Projectiles

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Peter J. K. Cameron ◽  
Peter H. Rogers ◽  
John W. Doane ◽  
David H. Gifford
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Measurement Techniques ◽  
Theoretical Models ◽  
Dynamics Simulation ◽  
Small Scale ◽  
Successful Operation ◽  
Six Degrees Of Freedom ◽  
Impact Location ◽  
Simulation Based

Applications and research utilizing supercavitation for high-speed underwater flight has motivated study of the phenomenon. In this work, a small scale laboratory experiment for studying supercavitating projectiles has been designed, built, and tested. Similar existing experimental work has been documented in literature but using large, elaborate facilities, or has been presented with ambiguous conclusions from test results. The projectiles were 63.5 mm in length and traveled at speeds on the order of 145 m/s. Measurement techniques are discussed and used to record projectile speed, supercavity dimensions, and target impact location. Experimental observations are compared with a six degrees-of-freedom dynamics simulation based on theoretical models presented in literature for predicting supercavity shape and hydrodynamic forces on the supercavitating projectile during flight. Experimental observations are discussed qualitatively, along with quantitative statistics of the measurements made. Successful operation of the experiment has been demonstrated and verified by agreement with theoretical models.

The Hexapodopter: A Hybrid Flying Hexapod—Holonomic Flying Analysis

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Daniel Soto-Guerrero ◽  
José Gabriel Ramírez-Torres
Keyword(s):  
Degrees Of Freedom ◽  
The Body ◽  
Design Criteria ◽  
Control Law ◽  
Two Degrees Of Freedom ◽  
Main Design ◽  
Walking Machine ◽  
Six Degrees Of Freedom ◽  
Thrust Vector ◽  
Thrust Forces

This document introduces the holonomic flying capabilities of the Hexapodopter, a six-legged walking machine capable of vertical take-off and landing. For ground locomotion, each limb has two degrees-of-freedom (2DoF); while the thrust required for flying is provided by six motors mounted close to every knee, so the thrust vector can be reoriented depending on the configuration of each limb. The capacity of reorienting the thrust forces makes the Hexapodopter a true holonomic vehicle, capable of individually controlling its six degrees-of-freedom (6DoF) on the air without reorienting any of the thrust motors nor the body. The main design criteria and validation will be discussed on this paper, as well as a control law for the vehicle.

The scientific bases of autocontrol with vibration phase for a resonance beating-vibration system with two degrees of freedom driven by debalances

1996 ◽  
Vol 18 (2) ◽  
pp. 43-48
Author(s):  
Tran Van Tuan ◽  
Do Sanh ◽  
Luu Duc Thach
Keyword(s):  
Degrees Of Freedom ◽  
Regulation System ◽  
Vibration System ◽  
Two Degrees Of Freedom ◽  
System Operating

In the paper it is introduced a method for studying dynamics of beating-vibrators by means of digital calculation with the help of the machine in accordance with the needs by the helps of an available auto regulation system operating with high reability.

Control of processing at multi-tool two-support setup

2020 ◽  
pp. 67-73
Author(s):  
N.D. YUsubov ◽  
G.M. Abbasova
Keyword(s):  
Degrees Of Freedom ◽  
Factor Model ◽  
Angular Displacement ◽  
Factor Models ◽  
Technological System ◽  
Displacement Control ◽  
Model Accuracy ◽  
Six Degrees Of Freedom ◽  
Angular Displacements ◽  
And Control

The accuracy of two-tool machining on automatic lathes is analyzed. Full-factor models of distortions and scattering fields of the performed dimensions, taking into account the flexibility of the technological system on six degrees of freedom, i. e. angular displacements in the technological system, were used in the research. Possibilities of design and control of two-tool adjustment are considered. Keywords turning processing, cutting mode, two-tool setup, full-factor model, accuracy, angular displacement, control, calculation [email protected]

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