Vehicle Technical Specification - Part 4

13 CHASSIS SYSTEM TARGET

[Issue 8; Configuration 10; 10th May 2010]

Definition	Unit	Target	Status 10th May 2010
Static Bending Stiffness	N/mm	>10,000	CAE REQ
Static Torsion Stiffness	Nm/deg	>10,000	CAE REQ
First Torsion Mode (fully trimmed with vehicle masses)	Hz	30	CAE REQ
First Bending Mode (fully trimmed with vehicle masses)	Hz	32	CAE REQ
Local attachment Point stiffness	N/mm	>25,000	CAE REQ

13.2 Wheels

Definition	Unit	Target	Status 10th May 2010	Comment
Wheel Diameter	mm	900	900
Wheel Width	mm	150	150
Wheel Rolling Diameter	mm	870	870
Rim Profile				"V" profile
Wheel Weight	kg	<100	149.3	Base Design Al.
Wheel Rotating Inertia	kg.m²	<5	6.901	Need to review options for carbon epoxy composite and CFMMC wheel
Peak Wheel RPM at 1050 mph	rpm	10304	10304
Specific surface loading (kg mass / mm wheel width)	kg/mm	<13	11.2

13.3 Front Suspension

Definition	Unit	Target	Status 10th May 2010	Comment
Static Geometry
Suspension Type				Double wishbone – Spring Damper to LCA
Ride Height Adjustment	mm	None within Suspension
Bump Travel	mm	100	50
Rebound Travel	mm	100	50
Total Travel	mm	200	100
Static Camber	deg	0	0
Static Castor	deg	6	5.99
Kingpin Inclination	deg	8	8.04
Hub Offset	mm	60	61.29
Ground Offset	mm	2	-0.19
Mechanical Trail	mm	100	99.29
Roll Centre Height	mm	0	0.04
Roll Centre Vertical Migration (To Ground)	m/m	1	n/a	Target not achievable with current suspension design (parallel wishbone)
Anti Dive	%	0	0
Anti Lift	%	0	0
Kinematics Characteristics
Toe Change	deg/m	0 to 0.1 toe out	0
Camber Change	deg/m	0	0
Castor Change	deg/m	0	0
Longitudinal Wheel Centre Change	m/m	0	0
Spring Characteristics
Suspension Rate	N/mm	200 to 300	250
Wheel Hop Frequency	Hz	12 to 20	12	Assuming 2000N/mm ground stiffness
Parasitic rate	%	<10	?
Suspension Frequency (Design Condition full with Fluids and Driver)	Hz	2 to 3	2.301
Suspension Frequency (Empty and driver)	Hz	2 to 3	2.773
Damper Ratio	mm/mm	<1.4:1	<1.363:1
Spring Ratio	mm/mm	<1.4:1	?
Front Roll Stiffness from springs	Nm/deg		2181
Spring Characteristics				Targets to be checked by FE and verified by compliance rig test
Parallel Lateral Force
Toe Compliance	deg/kN	0.1 toe out	CAE REQ
Camber Compliance	deg/kN	0.001	CAE REQ
Parallel Lateral Force 30mm Trailed
Toe Compliance	deg/kN	0.1 toe out	CAE REQ
Longitudinal Braking
Toe Compliance	deg/kN	0.001	CAE REQ
Caster Compliance	deg/kN	0.001	CAE REQ
Torque About Vertical Axis
Aligning Torque Compl.	deg/kNm	0.0005	CAE REQ

13.4 Steering system

Definition Design Condition	Unit	Target	Status 10th May 2010	Comment
Kinematic Characteristics
Overall ratio – Steering Wheel Angle (SWA) / Road Wheel Angle	deg/deg	25:1 to 30:1	30:1
Ackermann @ 5 deg	%	Undefined	0	Previously had 100%, now have 0%. Target needs defining as design progresses
Velocity Ratio Wheel to Pinion	%	<1% over 5deg SWA 3% over rest
Compliance Characteristics
Torsion Bar Compliance	deg/Nm	∞		PAS without torsion bar required
Total Steering Compl.	deg/Nm	<0.25
Column Backlash	deg	<0.25
Rack Mounting Compliance	mm/kN	<2
Steering Torque
Max Steering Effort	Nm	15
Column Friction	Nm	0.2
Torque gradient – Single Wheel Braking	Nm/kN	<0.00005

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