PCSAIL, A Velocity Prediction Program for a Home Computer

Mapping Intimacies ◽

10.5957/csys-2001-010 ◽

2001 ◽

Author(s):

David E. Martin ◽

Robert F. Beck

Keyword(s):

Design Stage ◽

Rapid Evaluation ◽

University Of Michigan ◽

Prediction Program ◽

Other Information ◽

Velocity Prediction ◽

Turn Around Time ◽

Excel Solver ◽

The University ◽

Boat Speed

An Excel Velocity Prediction Program has been developed to allow for rapid evaluation of yacht performance at the initial design stage. The required input consists of only the basic hull and sail dimensions. Empirical equations, based on these basic dimensions, are used for initial estimates of required hull parameters. As the design progresses the user can easily replace these default values with refined estimates or actual values. Because of its simplicity, and short turn around time, the program has been used as a teaching aid at the University of Michigan. Reconstruction of the program, PCSAIL, may be made with equations and other information provided in the Appendix. The Excel "Solver" has been found to be a reliable means of finding the equilibrium boat speed and heel angle. It seeks the maximum boat speed by adjusting the sail flattening factor, F, and reef, R, and the lateral location of the "movable crew." In the case of a hinged centerboard, or dagger- board, it will also adjust the draft for maximum boat speed. For sloop rigs the program will also take in the jib and set the spinnaker, at the appropriate wind angle, in order to gain maximum boat speed. The program plots the speed "polar," and velocity made-good, and determines the tacking angles.

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VPP-Driven Sail and Foil Trim Optimization for the Olympic NACRA 17 Foiling Catamaran

Journal of Sailing Technology ◽

10.5957/jst/2020.5.1.61 ◽

2021 ◽

Vol 5 (01) ◽

pp. 61-81

Author(s):

Kai Graf ◽

Oliver Freiheit ◽

Paul Schlockermann ◽

Jan C. Mense

Keyword(s):

Olympic Games ◽

Strong Impact ◽

Large Set ◽

Prediction Program ◽

Velocity Prediction ◽

Rudder Angle ◽

Boat Speed ◽

The Olympic Games

Abstract. The Nacra-17 catamaran is currently the only type of multihull that participates in the Olympic Games. It features semi-L-shaped daggerboards, allowing the boat to foil. For maximizing boat speed, the sailors have to cope with a large set of trimming parameters. Boat speed depends on sail trim, but additional trim parameters also have a strong impact on boat speed: the rake of the daggerboard and the rudder, the platform trim and heel angle and the rudder angle. The project described here tries to assist the sailors in finding an optimized set of trim parameters. This is done with the help of a proprietary velocity prediction program, which - besides solving for equilibrium of all forces acting on the boat - searches for the set of daggerboard and rudder rake, rudder angle, heel angle and platform trim, for which performance yields a maximum. The paper describes the method as well as some of the results.

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Enhanced Wind Tunnel and Full-Scale Sail Force Comparison

10.5957/csys-2007-003 ◽

2007 ◽

Author(s):

Heikki Hansen ◽

Peter J. Richards ◽

Peter S. Jackson

Keyword(s):

Wind Tunnel ◽

Quantitative Agreement ◽

Full Scale ◽

Force Balance ◽

Testing Procedures ◽

Prediction Program ◽

Surface Pressure Distribution ◽

Velocity Prediction ◽

The University ◽

Scale Data

This paper presents a comparison between wind tunnel and full-scale aerodynamic sail force measurements using enhanced wind tunnel testing techniques to model the full-scale sailing conditions more accurately. The first comparison was conducted by Hansen et al., 2003a, in the Twisted Flow Wind Tunnel (TFWT) at The University of Auckland and followed standard testing procedures. Since then enhancements have been made and two aspects not considered in the original comparison are highlighted here. The interaction of the hull and sail forces is now considered and trim changes of the sails due to wind strength are included. For the enhanced comparison the interaction between the hull/deck and the sails is investigated by installing a secondary force balance inside the model to measure the hull/deck forces and by pressure tapping the hull/deck to determine the surface pressure distribution. It is found that the presence of the sails significantly affects the forces on hull/deck when sailing upwind, which should be accounted for consistently in comparisons of full-scale, wind tunnel, and computational fluid dynamics (CFD) data. In the original comparison the sails were trimmed in the wind tunnel to the aerodynamically optimal shape by maximizing the drive force. Trim variations due to wind strength were however noted in full-scale data so that depowering is considered in the enhanced comparison. The sails in the wind tunnel were trimmed based on the fullscale wind strength and the yacht performance by employing a Real-Time Velocity Prediction Program (VPP) to achieve realistically depowered sail shapes. Utilising the enhanced wind tunnel techniques a generally good qualitative and quantitative agreement with the full-scale data was achieved, but a conclusive judgment of the accuracy of the comparison cannot be made.

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Prediction and Optimization of Aerodynamic Forces and Boat Speed of Foiling Catamaran with a Rig of a Rigid Wing and a Jib

10.5957/csys-2016-001 ◽

2016 ◽

Author(s):

Kai Graf ◽

Hannes Renzsch ◽

Janek Meyer

Keyword(s):

Optimization Method ◽

Hydrodynamic Flow ◽

Design Parameters ◽

Constraint Optimization ◽

Aerodynamic Forces ◽

Force Prediction ◽

Prediction Program ◽

Velocity Prediction ◽

Rigid Wing ◽

Boat Speed

This paper describes a method to calculate the aerodynamic forces generated by a rigid two-element wing together with a jib. Additionally, investigations of hydrodynamic flow forces generated by water-piercing L-shaped foils are introduced. The aerodynamic and hydrodynamic flow force prediction methods are combined in a velocity prediction program featuring a constraint optimization method in order to predict boat speed and wing and foil trimming parameters for its maximization. A velocity polar calculated by applying this method to a 50-foot catamaran is shown and the result of some studies are presented, varying design parameters of the catamaran.

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A Velocity Prediction Program for a Planning Dinghy

10.5957/csys-2005-014 ◽

2005 ◽

Author(s):

Todd Carrico

Keyword(s):

Hydrodynamic Resistance ◽

Side Force ◽

Prediction Program ◽

Fundamental Goal ◽

Velocity Prediction ◽

Sailing Yacht ◽

Series Of Experiments ◽

College Of Engineering ◽

The University ◽

Visual Basic 6.0

This paper summarizes the author’s graduate thesis in Naval Architecture accepted by the University of New Orleans, College of Engineering. The author sought to investigate the complicated interactions between the hydrodynamics and aerodynamics of a sailboat. The type of sailboat investigated was the Olympic dinghy class called the Laser. It was the author’s understanding that at that time, no work has been completed in the area of velocity prediction for this type of sailboat. Thus, the fundamental goal of this thesis was to develop a velocity prediction program specific to the Laser. In order to accomplish the goal of creating a velocity prediction program, multiple essential pieces of the data were needed. In particular, the hydrodynamic resistance data, aerodynamic drive and side force data, and hydrodynamic side forces were needed. To determine the dynamic trim of the dinghy, a series of experiments were conducted. In addition, a data acquisition system was developed in which full scale tow testing could be done. Next, a complete tow test series was conducted for the Laser. The aerodynamic sail coefficients were derived from Marchaj’s Aero-Hydrodynamics of Sailing. To determine the hydrodynamic side force, a two dimensional approach was employed. The coding of the velocity prediction program was done using Microsoft’s Visual Basic 6.0 and Excel 2000. The algorithms published in the 15th Chesapeake Sailing Yacht Symposium and Principles of Yacht Design pertaining to velocity prediction were used as a baseline. Finally, validation and verification was performed with the shareware program PCSAIL.

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Novae in the Magellanic Clouds

International Astronomical Union Colloquium ◽

10.1017/s0252921100073334 ◽

1979 ◽

Vol 46 ◽

pp. 96-101

Author(s):

J.A. Graham

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

University Of Michigan ◽

The Past ◽

Spectroscopic Information ◽

Objective Prism ◽

The University ◽

Small Cloud ◽

Low Dispersion

During the past several years, a systematic search for novae in the Magellanic Clouds has been carried out at Cerro Tololo Inter-American Observatory. The Curtis Schmidt telescope, on loan to CTIO from the University of Michigan is used to obtain plates every two weeks during the observing season. An objective prism is used on the telescope. This provides additional low-dispersion spectroscopic information when a nova is discovered. The plates cover an area of 5°x5°. One plate is sufficient to cover the Small Magellanic Cloud and four are taken of the Large Magellanic Cloud with an overlap so that the central bar is included on each plate. The methods used in the search have been described by Graham and Araya (1971). In the CTIO survey, 8 novae have been discovered in the Large Cloud but none in the Small Cloud. The survey was not carried out in 1974 or 1976. During 1974, one nova was discovered in the Small Cloud by MacConnell and Sanduleak (1974).

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