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Racetech Mark ortiz chassis Newsletter - allt om chassidynamik | 2 besök senaste veckan (35875 totalt) |
Mark ortiz är en chassi-konsult som bl a skriver i Race Car Engineering.
Han skriver också sedan 2000 ett månadsbrev där han besvarar frågor, och han har genom åren rett ut det mesta vad gäller chassidynamik Jag har gjort en sammanställning av hans mest informativa artiklar inom olika områden Längst ner finns också en lista på alla hans artiklar i kronologisk ordning, samt länk till en zip-fil med alla artiklarna. En del frågor berör oval-racing så läs artiklarna under "oval track concepts" först där han reder ut begrepp och termer zip med alla artiklar Utvalda artiklar inom olika områden oval track concepts June 2002 Some basic oval track concepts for road racers. May 2001 Rear Stagger versus static cross. Chassis troubleshooting guide July 2001 Chassis troubleshooting guide. July 2003b Chassis troubleshooting guide. August 2001 Things that make spring changes work backwards. october 2001 Balancing the car with camber and tire pressure. June 2001 Weight transfer in winged over sprint cars November 2001 Selecting springs. February 2002 Things that make spring changes work backwards, revisited. April, May, June 2003 Shock and spring forces. August 2003 Load transfer basics. September, october, November 2004 Tire load sensitivity and weight transfer in trail braking September, october 2005 Load transfer question. April 2006 Springs, bars and load transfer. June 2006 Effects of spring rates and damper settings during cornering. August 2007 Is it bad to lift a wheel? Front/Rear weight distribution March 2002 Racing front-drive cars. october 2002 Move the rear wheels back to improve traction? February 2003 More on rear wheel placement and traction. November 2003 Weight distribution and tire size. December 2003 More on racing front-drive cars and load transfer. April 2004 More on weight distribution. November, December 2005 optimizing engine-over-drive-wheels layout. Corner weight January, February 2004 Managing the behavior of the unbalanced. Roll center and roll axis May/June 2009 The anti controversy June 2004 More on F1 control arm angles. August 2004 Roll center migration, some more. December 2004 Roll center below ground. February 2006 Roll axis inclination. September 2006 Roll center in trailing arm front suspension. More on roll axis and related analytical concepts. May 2007 Roll axis for live-rear-axle road/hillclimb car Roll axis of the axle December 2004 Roll moments from longitudinal anti. Roll Center Myths and Reality Roll Center Myths and Reality (artikel av Wm. C. Mitchell) Polar moment of inertia July 2000 Polar moment of inertia. September, october, November 2004 Rear percentage versus yaw inertia. May 2006 Rear percentage or polar moment? Steering geometry August 2002 Steering geometry variables. Importance of steering rack placement. November 2002 Trail and steering feel. January, February 2005 Ideal spindle or steering geometry. Ackermann December 2002 Ackermann Recommendation. January, February 2004 Reverse ackermann or toe-in on ovals. December 2007 Ins and outs of toe and ackerman Shocks August 2000 The shock dyno lies! December 2001 Analyzing shock traces. January 2002 Suspension Natural Frequencies. February 2002 Some Basic shock questions. May 2002 Natural Frequencies revisited. February 2003 Shock research update. September, october 2003 Shock research update. November 2006 Stiff rebound damping. January 2009 Damping ratio Tires September, october, November 2004 Why are wide tires better? January 2007 Tall vs. short sidewalls June 2007 Large vs. small tire and wheel diameter Beam axle March 2003 Independent rear suspension for dirt? January, February 2004 Independent or beam front axle suspension for paved oval? July 2006 Beam axle pros and cons. october 2006 Twist beams and jointed de dion tubes. June 2007 Another triangulated four-link axle May 2004 Arm angles in triangulated four-bar beam rear axle. Panhard bars December 2000 Shorty panhard bars versus long ones. January 2003 Roll center with a j-bar/panhard bar August 2006 Panhard bar longitudinal location. Panhard bar jacking forces. July 2007 High or low panhard bar Frame stiffness and steel quality February 2001 Required frame stiffness. May 2001 Chromemoly in stock cars. Differentials December 2002 Torque, RPM and power distribution in differentials. December 2003 Single or dual brakes for FSAE March 2004 Differentiating differentials. March 2006 Diff differences Zero droop February 2007 Zero-droop setups July 2007 More thoughts on zero-droop setups, and related oval track spring split issues Center of gravity calculation September 2002 Front and rear center of gravity. Winter reading November 2000 Winter reading material. Alla artiklar i kronologisk ordning May 2000 Questions about a roundy-round camaro. June 2000 Question about relative rear spring stiffness for roundy-round. July 2000 Brake failure in late model pavement cars. Polar moment of inertia. August 2000 The shock dyno lies! September 2000 Wheel Alignment and Caster october 2000 Checking Rear Axles. Torque arm or pull bar? November 2000 Winter reading material. December 2000 Springs, roll and cornering balance. Shorty panhard bars versus long ones. January 2001 Wind tunnel testing for short track cars. Rear Caster. Stacked coilover springs. February 2001 Required frame stiffness. Making ballast weights. March 2001 Safety Issues - Hans device and soft walls. April 2001 5th Coil location and rate. May 2001 Chromemoly in stock cars. Rear Stagger versus static cross. June 2001 Weight transfer in winged over sprint cars. July 2001 Chassis troubleshooting guide. August 2001 Things that make spring changes work backwards. September 2001 Stock car safety issues. Tire Data. october 2001 Balancing the car with camber and tire pressure. November 2001 The big tracks and their big wrecks. Selecting springs. December 2001 Analyzing shock traces. January 2002 Suspension Natural Frequencies. February 2002 Winston Cup Harness Installation. Things that make spring changes work backwards, revisited. Some Basic shock questions. March 2002 Racing front-drive cars. April 2002 Quads on Pavement. May 2002 Natural Frequencies revisited. Spaceframe or monocoque? Tire care. June 2002 oily tires. Some basic oval track concepts for road racers. Narrower rear track than front. July 2002 Braking/downshifting technique. August 2002 Steering geometry variables. Importance of steering rack placement. Bumpsteer as ackermann modification. The old torque/horsepower controversy. September 2002 Pantera front end revisited. Horsepower and torque revisited. Front and rear center of gravity. october 2002 Move the rear wheels back to improve traction? November 2002 Another Tire care tip. Pull rods, push rods or both? Trail and steering feel. Kart scaling. December 2002 Ackermann Recommendation. Torque, RPM and power distribution in differentials. January 2003 Tire warmers. Spring placement on triangulated 4-link. Roll center with a j-bar. February 2003 Shock research update. More on rear wheel placement and traction. March 2003 Independent rear suspension for dirt? April, May, June 2003 Shock and spring forces. July 2003 Right rear spring stiffest? Influence of pushrod angle on wheel rate. July 2003b Chassis troubleshooting guide. August 2003 Load transfer basics. September, october 2003 Shock research update. November 2003 Weight distribution and tire size. Width versus drag. December 2003 More on racing front-drive cars and load transfer. Single or dual rear brakes for fsae? January, February 2004 Reverse ackermann or toe-in on ovals. Managing the behavior of the unbalanced. Independent or beam front axle suspension for paved oval? March 2004 Differentiating differentials. April 2004 Effect of caliper mounting position. More on weight distribution. Spring splits with big bars. May 2004 The new nascar tire. Control arm angles in F1. Arm angles in triangulated four-bar beam rear axle. June 2004 More on F1 control arm angles. Clutch use when downshifting. July 2004 Setup for lower grip. Lowering blocks on truck arms. ohlins high-frequency pistons. Which shock to soften? August 2004 Roll center migration, some more. September, october, November 2004 Tire load sensitivity and weight transfer in trail braking. Why are wide tires better? Rear percentage versus yaw inertia. Roll springing preload in monoshock setups. Why so few rear monoshock setups? December 2004 Roll center below ground. Roll moments from longitudinal anti. January, February 2005 Ideal spindle or steering geometry. March, April 2005 Finer points of anti-roll bars on stock cars. May, June 2005 Too much left percentage? July, August 2005 Dynamics of three-wheelers. September, october 2005 Load transfer question. November, December 2005 optimizing engine-over-drive-wheels layout. January 2006 Tires in the snow. February 2006 Roll axis inclination. March 2006 Diff differences. April 2006 Springs, bars and load transfer. May 2006 Rear percentage or polar moment? June 2006 Effects of spring rates and damper settings during cornering. July 2006 Beam axle pros and cons. August 2006 Panhard bar longitudinal location. Panhard bar jacking forces. September 2006 Roll center in trailing arm front suspension. More on roll axis and related analytical concepts. october 2006 Twist beams and jointed de dion tubes. November 2006 Twist beams and jointed de dion tubes. December 2006 Twist beams and jointed de dion tubes. January 2007 Tall vs. short sidewalls Braking distance, brake torque and tire traction February 2007 Modern driveshaft joint vs. rubber doughnuts Zero-droop setups March 2007 Diamond layout April 2007 Roll steer and anti-squat/ant-list in strut suspension May 2007 Roll axis for live-rear-axle road/hillclimb car Roll axis of the axle June 2007 Another triangulated four-link axle Large vs. small tire and wheel diameter July 2007 More thoughts on zero-droop setups, and related oval track spring split issues High or low panhard bar August 2007 Is it bad to lift a wheel Hollow vs. solid anti-roll bars December 2007 Ins and outs of toe and ackerman January/February 2008 More exotic vehicle layout ideas March 2008 Another exotic car layout April 2008 Late Corvair rear suspension May 2008 Another pony car suspension from the '60's Really quick steering June 2008 Why not go for 100% camber recovery Gyros for roll stability July 2008 Front to rear track ratio August 2008 Dirty tricks Porsche 993 rear suspension September 2008 Monoshock suspensions, z-bars, Stock car front ends with bump rubbers october 2008 Differentials and yaw control November 2008 Yaw moments from diffs with front-wheel drive Turn-in on slippery surfaces December 2008 Controlling AWD front/rear torque split on a budget Is there such a thing as too big tires January 2009 Damping ratio February 2009 Camber recovery March 2009 Trailing arms with torsional rubber springing Ride and roll rates with monoshocks April 2009 Raised lower control arms on 2009 F1 cars Pullrod suspensions in F1 Rate and length numbers on torsion bars May/June 2009 The anti controversy zip med alla artiklar PS. ...och ja, det är en helt laglig nedladdning : "The Mark ortiz Automotive CHASSIS NEWSLETTER PRESENTED FREE OF CHARGE AS A SERVICE To THE MOTORSPORTS COMMUNITY " _________________ Johan Lekås |
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670 sidor http://lek.holy.se/mark_ortiz_2000-2 for f in ls *.doc; do abiword --to="$f.pdf" "$f"; done; pdftk *.pdf cat output mark_ortiz_2000-2007.pdf De sista årets var av något konstigt properitärt format så jag kan inte garrantera någon om konverteringen... _________________ Markus Ålind |
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Det här borde väl klistras, och materialet laddas upp på rejsa för att inte riskera döda länkar om ett par veckor?
Fint jobb annars. Laddade ner den när tråden var ny, men har fortfarande inte hunnit läsa mer än ett par tre stycken. |
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Materialet är i säkert förvar och det kommer komma en tråd med dessa inom kort.
Tills vidare får ni använda det som ligger här i tråden. _________________ Dodge pickup -58 Dodge Dart -67 Plymouth Cuda -71 Plymouth Cuda Conv -70 VaGinetta G20 Opel Speedster Ford Cortina Anders Bisting |
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Bra, ville bara väcka tanken. |
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Har uppdaterat första inlägget i tråden med alla artiklar t o m juni 2009
Den senaste artikeln May/June 2009 "The anti controversy" tycker jag personligen är bra där han går till botten med anti dive/squat och roll centrum (som ju egentligen är samma resonemang i sido-vy respektive front-vy), och även behandlar "force based roll centers" (beskrivs i den här artikeln Roll Center Myths and Reality av Mitchell) _________________ Johan Lekås |
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och "forcebased roll centers" är nåt man bör ta till sig och inte förlita sig till det geometriska vilket är helt intetsägande då hjulen har olika last, vilket dom har när man svänger.
_________________ Ove Sponton Det var inte jag. Dessutom var det ingen som såg mig. |
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_________________ Johan Lekås |
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Ajajaj, Marks artikel är ju på 12 sidor och Mitchells är ju inte så kort den heller. En snabb genomläsning av bägge har jag dristat mig till så här mitt i natten dock. Med reservation för att jag la 10 min att ögna genom bägge, tiden på dygnet osv. Mitchell räknar krafter i markplanet, räknar om till ett kraft momentsystem i tyngdpunkten och tar det där i från. Var Mitchell verkar gå bort sig är att han trasslar till det med var reaktioner bärs om hjulmomenten tas i den fjädrade eller ofjädrade massan. Mark kommenterar väl nåt åt det hållet åxå. Gör man bara rätt borde det bli rätt åxå. Mark verkar köra nån kombination av momentancenter, viktning dom emellan och hoppla så får han sina resultat. Tyngdpunkten kom inte in i Marks resonemang vilket det gör i Mitchell, men där används bara tyngdpunkten som en referenspunkt för kraft/momentsystemet ekvationerna är uppsatta i. Marks förenklade viktning av momentancenter är inte lika generell som en "riktig" kraftanalys är, men i rimligt symmetriska fall duger den. Nu hann jag inte fördjupa mig i hur han viktar de respektive momentancetrumen så jag kan inte kommentera det. Tyngdpunktens position i sig påverkar inte rollcentrets position även om man har det med i beräkningen (i Mitchells fall), det utgör bara enkel referens i ett lokalt koordinatsystem. Det finns ett väldigt bra SAEpapper rörande kraftbaserat rollcenter versus "geometriskt" dito. Ska se om jag hittar igen det så ska jag väl kunna lägga upp det nånstans (om man får) Nä, god natt på er. _________________ Ove Sponton Det var inte jag. Dessutom var det ingen som såg mig. |
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Det står ganska mycket i artikeln eftersom den är ett svar på en annan artikel i RCE , men det jag tycker är kärnpunkterna är: - Rollcentrum (front-vy) och pitchcentrum (sido-vy) beräknas/behandlas på samma sätt. - Tyngdpunktens position påverkar inte roll- och pitchcentrum - Det är bara roll- och pitchcentrums höjder som är intressanta eftersom de krafter som verkar vid sido/längs-acceleration är horisontella (dvs har ingen verttikal komponent) Definition av rollcentrums höjd: Den höjd där en horisontell (centripetal-) kraft kan verka utan att orsaka roll. Mark ortiz metod att hitta rollcentrums höjd: Dra en linje från hjulets kontaktytan till fjädringens momentanpunkt för inner- respektive ytterhjul. Dra sedan en vertikal linje som delar spårvidden i samma proportioner som sidokraften fördelar sig mellan inner och ytterhjul (Den vertikala linjen ska ligga längst ifrån det hjul som ger störst sidokraft) Den vertikala linjen skär nu de två linjerna till momentanpunkterna för inner respektive ytterhjul. Rollcentrumet ligger på den vertikala linjen mittemellan de två skärningspunkterna EDIT: bild _________________ Johan Lekås |
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Racetech Mark ortiz chassis Newsletter - allt om chassidynamik | 2 besök senaste veckan (35875 totalt) |