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Racing by the Numbers - 2001 Development

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January

 1)   MacPherson Strut suspension is added to WinGeo3. This suspension is used in several production-related series around the world. This type of suspension has a lower A-arm with the bottom of the strut. The upper end of the strut is mounted to a specific point on the chassis rather than an A-arm.  It was available in the DOS Freebody program but was not available in the first version of the Windows WinGeo3 suspension geometry program.

  2)   Five-Link Independent suspension is added to WinGeo3. This is similar to Double A-arm except that the two upper links may have two separate mounts on the upright rather than a common ball joint. The two lower links may have two separate mounts on the upright rather than a common ball joint. There may be five separate mounting points on the upright.  Double A-arm is a specific form of Five-Link suspension. This type of suspension is most often used on the rear of sports cars where there is no steering input.

 3)    Trailing Arm suspension is added to WinGeo3. This is a form of Double A-arm where the inboard pickup points are on a single axis. The DOS Freebody program could handle this type of suspension but the WinGeo3 program simplifies the input process. A specific input form automatically generates the extra points.

 4)    Three-Link solid rear-axle suspension is used on sedans and stock cars. This type of suspension was handled in the DOS Freebody program.  A Panhard rod is used for lateral location. Springs and shocks may not be attached to the links.  Watts links can not yet be modeled.

 5)    Four-Link solid rear-axle suspension is added to WinGeo3. This is common on stock cars and racing sedans. The extra link requires that the rear-axle be able to twist in the middle. In the DOS Freebody program one of the four links was ignored because the system was over-determined.  A Panhard rod is used for lateral location. Springs and shocks may not be attached to the links.

 6)    Truck-Arm solid rear-axle suspension is added to WinGeo3. This common stock car rear suspension is treated as a four-link solid rear axle but the program automatically generates the extra mounting points. A Panhard rod (or track bar) is used for lateral location. Caster values allow the user to see how much the rear axle twists. Springs and shocks may be attached to the truck arms.

 7)    Third Springs may be attached to U-bar anti-roll bars.  A third spring is attached to a link mounted on the anti-roll bar.  Rotation of the anti-roll bar is assumed to be linear along the effective length of the bar. The third spring is designed to move with ride height changes but to be insensitive to chassis roll.  Third spring movement can be displayed as well as the derivative expressed as either a motion ratio or a velocity ratio.

 8)    T-bar anti-roll bars are most often used with Push-rod and Pull-rod suspensions. The T-bar twists when the chassis rolls but rotates fore-aft when the chassis moves vertically. A Third Spring can be attached to the T-bar to restrict vertical movement.

 9)    Trace Roll Center allows the user to follow the movement of the roll center as the chassis moves. The trace displays 20 previous roll center locations so the user can easily see how the roll center moves. This is very effective when used with a path.

 10)  Moment Arm can be displayed rather than the Roll Center location.  The Moment Arm is the vertical distance from the roll center to the center of gravity.  A constant Moment Arm is often a design goal. This means the roll center moves vertically with the chassis or C.G.

 11)  The Jacking Force Incline Angle can be displayed on the primary graphic screen. This angle is expressed in degrees.

 12)  Ackermann value can be displayed on the screen.  This value only appears when there is a steering input. The Ackermann value is a percentage of the wheelbase.  100% Ackermann has the intersection opposite the rear axle.

 13)  Anti-Dive, Anti-Squat values for either inboard or outboard forces can be displayed on the screen.

 14)  The Compute menu now allows the user to solve for Shock position and Steering angle.  This is very helpful for Draglink suspensions where the relationship between steering input and steering result is not obvious. It is particularly convenient when the data acquisition system is calibrated to show steering angle at the tire contact patch.  This was suggested by Bob Leonard of The Leonard Company in Mooresville, N.C.

 15)  Wheel Travel values may be displayed on the screen.  The Compute menu can also solve for Wheel Travel. If you know the car is crossing a one-inch bump on the right side the user can specify this condition and the program will compute the proper ride and roll to equal a one-wheel bump. This was suggested by Warren Rowley of Calgary, Alberta, Canada.

 16)  Notes can be placed on the screen and edited.  Each note may be a specific color and may or may not have a box around it. It may have a pointer. This is very effective for creating reports. This is more effective than the old Notemaker commands.

 17)  The Font for the graphical display can be changed. This is very effective in tailoring the program for your application. Use a large font for simple displays; choose a smaller font to display more values on screen.

 18)  A Demo version of the WinGeo3 geometry program is now available. This is a fully-functional program that does everything except save files. It can be used to evaluate the WinGeo3 program.

 19)  The program can now be delivered on CD-Rom.  Previously the program was only available on floppy diskettes.

 February

 1)    Verify Computations is added to the Reports menu.  This allows the user to see and verify the results of the suspension computations. It is very useful to the programmer and users may utilize it to verify models and computations.

 2)    The Draglink edit screen now shows inclination angles. This should help eliminate some input errors.

 3)    Solid Rear-axles can now twist in the middle to properly model four-link suspensions.  Previous analysis of four-link systems ignored one link.

 4)    Five-Link Independent suspensions can now be modeled. These have five separate links from the chassis to the upright. Double A-arm suspensions have five links but only three attachments on the upright. Five-Link systems can have five distinct mounts on the upright.  These suspensions are usually used at the rear of sports cars.

 5)    Trailing-Arm suspensions can be modeled. These are treated as Double A-arm where the inner mounting points are one axis.

 6)    Paths can now specify Wheel Travel. Paths can also mix different computations, such as solve for Shock with specific chassis positions or wheel travels.

 7)    Ackerman values may now be displayed on the primary graphic screen.

 8)    A Rear data panel allows separate input for front and rear suspension positions when two different suspensions are being handled at the same time.

 9)    The user may now Trace a suspension Point on the screen.  This is a good way to see where a portion of the rear axle goes as the chassis moves.

 10)   The GAP results now includes Caster, Caster Trail, Kingpin and Scrub Radius.  These variables can now be plotted in the GAP analysis or saved in files.

 11)  The Display program can now perform polynomial Contour Fits to suspension data. This can provide simple mathematical formulas to describe suspension data.

 12)  Derivative Analysis in the Results menu compares theoretical estimations from instant center locations with the actual suspension computations.  This helps the user understand the suspension information provided by instant centers.

 13)  Old files are saved with the extension *.~ge.

 14)  A major effort was made in memory handling by the WinGeo3 program. The original program was often careless in memory handling and would often fill the memory of even the largest computers after a few thousand computations. After improving the memory handling the program can perform over 500,000 computations without problem.

 March

 1)    Rising Rate analysis has been added to the Reports menu. This report determines the change in motion ratio (and thus wheel rate) as the suspension moves through it’s range of motion.  This was suggested by Geoff Aldridge in the UK.

 2)    The Table feature allows a quick and convenient display of multiple suspension positions. The Table can be used to create bump steer reports or Ackerman steering analysis. The Table can even trace the location of a suspension point. Contents of the table can be printed, saved or plotted.

 3)    There are eight pre-defined Table Layouts in the program.  Eventually the user will be able to define his own Table layouts.

 4)    Path files can be quickly created with a variety of Ride, Roll or Steer positions.  These simple paths can be used to produce Table reports.

 5)    Pinion Angle can be computed and displayed for driveshafts.  Independent suspensions can have halfshafts; solid-axle suspensions can have a driveshaft.

 6)     The Compute: Setup now allows the user to change the length of a Push-rod or Pull-rod suspension. This computes the change in spring length necessary to offset a change in rod length. The rod length can be changed to re-position the suspension and alter the rising rate characteristics.  The DSTP Atlantic team asked for this change.

 7)    The Print text command can now save a text file.  This is convenient for creating reports and documenting analysis.

 8)    T-Bar third springs can now be used.

 9)    Derivative Analysis (determining instant centers from suspension computations) now applies to solid rear-axle suspensions.

 April

 1)    A Reasonableness Check is added to the Edit menu. This feature reviews suspension data in search of common errors. The program checks that the ball joints are in the vicinity of the wheel and that the upper ball joint is above the lower ball joint.  This can avoid wasted time and effort.

 2)    A Preview Files feature allows the user to quickly examine a variety of files. The Preview will list all the files in one directory or specified files. Each file is listed with filename, description, creation date and time, and notes. For geometry files the user can also compare two files and see all differences.  This is very convenient for comparing and eliminating duplicate files.

 3)    The Origin can now be displayed graphically.  This assists in verifying that the suspension data is entered properly.  This will reduce data-entry errors.

 4)    WinGeo3 can now save BMP (bit-mapped graphic) files. The same options are available as the Save-to-Clipboard functions in the Clipboard menu.  The BMP files can then be copied into reports.

 5)    Pitch Center analysis is available in the Reports menu.  The Pitch Center is similar to the Roll Center but applies to the longitudinal axis.

 May

 1)   The Geometry Control Dialog Explanations (similar to the tutorials of the DOS Freebody program) now have text defining suspension terms such as Instant Center and Roll Center.  These on-screen definitions provide ready access to documentation.

 2)   Racing by the Numbers software can now be shipped with multiple programs on one CD-Rom.

 3)   Created a WinGeo3 Demo for distribution with Paul Van Valkenburgh’s book Race Car Engineering and Mechanics.

 4)    The WinGeo3 documentation has been revised and enhanced with additional material and new chapters.

 5)   GAP plots can now swap X-axis and Y-axis thus permitting plots with Ride height as a vertical axis.

 6)   The user may change the font used on graphical displays.

 June

 1)   Print Text can now add a margin on the left side. This produces nicer looking reports that can be easily put into a binder.

 2)   Implement Roll Center for solid rear axles.

 3)   Add the capability to enter and edit spring and antiroll bar rates. These are used in the Load calculations.

July

 1)  MacPherson Strut spring can be attached to hub rather than lower A-arm. This corrects an error in the DOS Freebody formulation of MacPherson Strut suspensions.

2)   Improve Ackerman analysis.

3)   Implement Halfshaft angle analysis.

4)   Start work on Steering Axis analysis.

August - September

1)   Implement SVSA analysis.

2)   Fancy Print / Dynamic now shows current distances between points.

October

1) . Fix Solve-for-spring with solid rear axle suspensions bug. Previously solve-for-spring did not work with solid rear axle suspensions.

2)   Implement N/A as a value for undefined circumstances, like the intersection of parallel lines in instant center and SVSA computations.

3)  Implement error-warning levels. The user can choose to omit annoying warnings of minor errors, such as undefined instant centers due to parallel lines.

November

1)  Create Regular and Advanced versions of the suspension program, now 3.04

2)  Work on Advanced reports.

3)  Implement Tire Deflection calculations - both Solve for Load and special report

4)  Verify Problem to eliminate endless error messages after bad input.

5)  Straighten out T-bar and U-bar swaybars: produce special report

6)   Partial implementation of Watts-Link capability.

December

1)  Win SAE Award for one of ten best products in 2001.

2)  Create Special Displays - graphic representations of Tire Squish or Ackermann.

3)  Work on Instant Center Analysis.