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Landsailer and Iceboat design and construction

Current record of 116.7 mph was set 3/20/99 by 'Iron Duck'

Iron Duck

Windjet - new land craft - Lake Lefroy, Australia

JavaSingle preliminary velocity prediction for new land craft - 136.3 mph in 30 mph wind

results based on:
(approximate dimensions - estimated from photographs of the new yacht)
frontal area - cockpit, axle and fairings  - 26 sqft ?
sail area - 85 sqft ?
aspect ratio - 12 ?
wind speed - 30 mph
yacht weight 800kg + full ballast load 300kg = 2420 lbs
rolling resistance data for tires on dry lake surface at high speed - 
NASA Technical Memorandum 4808

A Model for Space Shuttle Orbiter Tire Side Forces Based on NASA Landing Systems Research Aircraft Test Results

Forces generated by the Space Shuttle orbiter tire under varying vertical load, slip angle and speed ( 50 to 230 mph ) were measured on lakebed runways at the Edwards Air Force Flight Test Center

http://www.dfrc.nasa.gov/DTRS/1997/PDF/H-2168.pdf(1.13 MB)

JavaFoil - java airfoil analysis program - http://www.mh-aerotools.de
Created by Dr. Martin Hepperle, scientific staff member at the Institute of Aerodynamics and Fluid Technology at the DLR in Braunschweig, Germany

Extensive online documentation - features include multi-element airfoil sections, ground effect (for inverted airfoil axles), airfoil design and modification - view velocity distribution, flow field, boundary layer, and polar graphs for lift, drag and moment coefficients

You may also download a standalone version of JavaFoil from the JavaFoil website

Index of Design Tools & Tips at rclandsailing.com

OVERVIEW OF DESIGN ISSUES

LANDYACHT VELOCITY PREDICTION PROGRAM

Program description:
Landsail.m (available for download on the Design Tools & Tips page) is a Matlab script written to predict speed and loading on a landyacht, based on yacht configuration, wind conditions and vehicle heading

Running the script requires Matlab, or you will need to convert the algorithm to some other programing language (see java version below). But you can at least view the file with wordpad

The algorithm doesn't make any assumptions about the size of the landyacht and so is valid for models and full size landyachts alike

RIG DESIGN TOPICS:

Wing Mast Experiments
Sail Design Tool
Why Landsailers Don't Have Jibs
LS Mast System

PLATFORM DESIGN TOPICS: 

Wheel Selection 
Bearing Selection 
Optimum Center of Mass (ballast location) 
Expected Loads 
Beam Bending Analysis Tool 
Speedometer Setup 
Generating down force with rear beam

JavaLandsail - java implementation of Kristopher Seluga's Mathlab landyacht velocity prediction program Landsail.m

Run applet here

View Java source code

To download a stand-alone version of JavaLandsail -

Directions:

Press Wind & Wing, Fuselage & Wheels or Crossbeam to change paramaters

Press Reset Default Parameters (bottom left corner) to restore default values

Press CALCULATE & PLOT DATA to obtain results

This program finds the maximum velocity vs heading of a landyacht based on:

 

True wind speed

Symmetric wing Lift/Drag correlations

• Drag coefficient at zero angle of attack
• Wing span, area & aspect ratio
• Lift reduction after stall angle is reached

Parasitic drag

• Fuselage Drag
• Crossbeam drag
• Wheel rolling resistance

Flipping criteria

• Vehicle weight and geometry
• Down force generation

Side slipping

• Available friction force
• Down force generation

Number of wings/sails

Number of wheels (3 or 4)

Tom Speer's Home Page -  http://www.tspeer.com
Information on aerodynamics, landyacht and multihull sailboat design.

Index of Landyachts section at tspeer.com

Photos of landyacht with rigid wing rig

Landyacht testbed build by Landyacht Design Interchange Association (LYDIA). This was a proof-of-concept vehicle used to try out new ideas in landyacht design and to investigate technical issues associated with the twin wing landyacht concept.

Wind Tunnel Test Report

Wind tunnel test data and performance prediction of the landyacht built by LYDIA

Simple Landyacht Velocity Prediction Program

SINGLE WING LANDYACHT PERFORMANCE PREDICTIONS WITH VELOCITY DEPENDENT ROLLING RESISTANCE 

HTML version of a simple velocity prediction program (VPP) for landyachts. Not executable, but shows all the derivation and sample results. Includes link to an executable version of the program Single.mcd (requires Mathcad - a numerical calculation and visualization software package).

Get Mathcad Explorer, a free read-only version of Mathcad -

Mathcad Explorer 7 
http://jurere.mtm.ufsc.br/~marcelo/calc_b/mathcad/mcexp703.exe   (6.7MB)

Mathcad Explorer 8 
http://sliunix.lanecc.edu/~jamies/mcexp802.exe  (12.1MB)

Google search for Mathcad Explorer 7 & 8

Or try JavaSingle, an extended java version of Single.mcd - see below.

Performance of a Class IV Design 

Predicted performance for a notional landyacht powered by a rigid wing

Single Wing Parametric Study

A parametric study of the effects of wing planform on the efficiency and heeling moment of an isolated wing as would be used as the sail rig for a landyacht.

Twin Wing Concept

The origin and rationale for a landyacht which is powered by two rigid wings mounted in an "A" frame arrangement. Results include renderings of the concept and initial feasibility studies.

Twin Wing Parametric Study

A parametric study of the effects of wing planform on the efficiency and heeling moment of two isolated wings as would be used as the sail rig for a landyacht.

JavaSingle - java implementation of Tom Speer's Mathcad landyacht velocity prediction program Single.mcd

Run applet here

View java source code
 

To download a stand-alone version of JavaSingle - Create a JavaSingle directory on your home computer Right click here and Save Target As JavaSingle.html in your new JavaSingle directory Download JavaSingle.jar (the java program) to your JavaSingle directory. Open JavaSingle.html in the JavaSingle directory with your browser to run program

Select a program variable, define a start value, end value and number of steps. JavaSingle automatically calculates landyacht performance over a 180° range of headings for each step, creating a polar plot of the results

Also displays a summary of performance data at maximum speed, including yacht heading, thrust, horsepower produced, sail lift, drag (sail, wheels and aerodynamic fuselage drag), sideforce and more as both coefficients and forces

Graph options -

• program variable steps - 1 to 10 or optionaly 50, 100, 200 - (default 5)
• calculation tolorance - (default .0001)
• heading increment 1° to 10° (default 5°)
• maximum speed scale - 20 mph to 200 mph - (default 80 mph)
• plot display - lines, points or both (default both)

Program variables -

• operational altitude (air density)
• wind speed mph
• sail area sqft
• sail aspect ratio
• maximum lift coefficient
• drag coefficient 
• oswald efficiency
• gross weight lbs 
• breakout friction
• rolling coefficient
• sideforce coefficient
• maximum sideforce G

JavaSingle extends single.mcd to include yacht fuselage aerodynamic forces -

• frontal area
• fuselage lift coefficient
• fuselage drag coefficient

In the 70's Windmobile incorporated rigid wing sails with streamlined wheel fairings, fuselage and bubble canopy cockpit to decrease aerodynamic drag to a minimum. The present world speed record holder, Iron Duck, and contender Windjet, adopt these same design features - employed by James L. Amick over a quarter century earlier!

Iron Duck - visit website

Windjet - visit website