Problem set 2 -week 3 challenge : Anti-Characteristics
Please Note: All formulas, caluclations and values can be found in the Excel file attached...
1. Calculate the following parameters
Stepwise Instructions:
- Calculate the Load Transfer
- Using LT, calculate the Front and Rear Axle Weight
- Calculate the Wheel Rate
- Calculate the Throttle Acc (g)
- Calculate Front and Rear end deflectiong using Wheel Rate
- Calculate Pitch Angle using Front and Rear deflection
- Calculate Pitch Gradient using Pitch Angle and Throttle Acc
Front end deflection under load
(LT*0.5)/Front Wheel Rate
= 0.631512444 in
Rear end deflection under load
(LT*0.5)/Rear Wheel Rate
= 0.487128189 in
Pitch angle
atan((Front def + Rear def)/WB)*(180/pi)
= 0.653985751 deg
Pitch gradient
Pitch Angle/Throttle Acc
= 1.295897919 deg/g
2. Use the IC location information to calculate the following
Stepwise Instructions:
- Calculate Front anti-lift angle using FICV, FICH and Tyre Radius
- Calculate Rear anti-squat angle using RICV, RICH and Tyre Radius
- Caluclate Front and Rear SA Angle for 100% anti-lift/anti-squat (w/o comp.) using CG Height aand WB
- Calculate Rear anti-squat % using Rear anti-squat angle, Rear SA angle and Drive Ratio
Front anti-lift angle
atan((FICV - Tyre Radius)/FICH)*(180/pi)
= 3.45366161 deg
Rear anti-squat angle
atan((RICV - Tyre Radius)/RICH)*(180/pi)
= 6.044092162 deg
Front swing arm angle for 100% anti-lift
atan(CG Height/WB)*(180/pi)
= 9.84113176 deg
Rear swing arm angle for 100% anti-squat
atan(CG Height/WB)*(180/pi)
= 9.84113176 deg
Front anti-lift %
= 0%
Rear anti-lift %
(Rear anti-squat angle*((100 - Drive Ratio)/100))/Rear swing arm angle
= 61.41663693%
3. To eliminate the pitch angle (theoretically), keep the rear swing arm height fixed at 16 inches from the contact patch. Calculate the following
Stepwise Instructions:
- Calculate the Rear anti-squat angle using RICV, Tyre Radius and RICH. Note- the RICH will be adjusted through the iterations.
- Calculate the Rear anti-squat % for zero pitch angle using the Rear anti-squat angle just calculated, along with Rear swing arm angle calculated in Q2.
- Calculate the Front and Rear End Deflection using the Front and Rear Eng Deflection (w/out comp.) and the Anti-Lift and Anti-Squat %'s.
- Calculate the Pitch Angle Verification using the Front and Rear End Deflection (w/ comp.) and WB
- Adjust RICH value used in step 1 and repeat following steps until a pitch angle value as close to 0 is obtained
Front anti-lift % and rear anti-squat % for zero pitch angle
Front anti-lift % for zero pitch angle = 0%
Rear anti-squat % for zero pitch angle = (Rear anti-squat angle*((100 - Drive Ratio)/100))/Rear swing arm angle = 227.9513319%
, where Rear anti-squat angle = atan((RICV - Tyre Radius)/RICH)*(180/pi) = 22.43299092
Front end deflection under load, accounting for the new anti characteristics
Front End Deflection (w/ comp.) = Front Deflection (w/o comp.)*((100 - Anti Lift %)/100)
= 0.631512444 in
Rear end deflection under load, accounting for the new anti characteristics
Rear End Deflection (w/ comp.) = Rear Deflection (w/o comp.)*((100 - Anti Squat %)/100)
= -0.623287006 in
Pitch angle, accounting for the new anti characteristics (verify that it is indeed zero)
atan((FEDwithcomp + REDwithcomp)/WB)*(180/pi)
= 0.004809009 deg