Chapter_2_Equations

Chapter_2_Equations - THE PENNSYLVANIA STATE UNIVERSITY...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: THE PENNSYLVANIA STATE UNIVERSITY Department of Civil and Environmental Engineering CE 321: Highway Engineering Chapter 2: Road Vehicle Performance Equations Section 2.2 – Tractive Effort and Resistance F f + F r = ma + R a + R rlf + R rlr + R g (2.1) where: F f = available tractive effort of front tires (lb) F r = available tractive effort of rear tires (lb) m = mass of vehicle (slugs) a = acceleration (ft/s 2 ) R a = aerodynamic resistance (lb) R rlf = rolling resistance of front tires (lb) R rlr = rolling resistance of front tires (lb) R g = grade resistance (lb) F = ma + R a + R rl + R g (2.2) where: F = F f + F r = available tractive effort delivered by front and rear tires R a = aerodynamic resistance (lb) R rl = rolling resistance of front and rear tires (lb) R g = grade resistance (lb) Section 2.3 – Aerodynamic Resistance 2 2 V A C R f D a ρ = (2.3) where: R a = aerodynamic resistance (lb) ρ = air density (slugs/ft 3 ) C D = coefficient of drag (unitless) A f = frontal area of vehicle (ft 2 ) V = vehicle speed (ft/s) 1100 3 V A C hp f D R A ρ = (2.4) where: hp Ra = horsepower required to overcome aerodynamic resistance (hp) ρ = air density (slugs/ft 3 ) C D = coefficient of drag (unitless) A f = frontal area of vehicle (ft 2 ) V = vehicle speed (ft/s) Section 2.4 – Rolling Resistance R rl = f rl W (2.6) where: R rl = rolling resistance (lb) f rl = coefficient of rolling resistance (unitless) W = vehicle weight (lb) ) 147 1 ( 01 . V f rl + = (2.5) where: f rl = coefficient of rolling resistance (unitless) V = vehicle speed (ft/s) 550 WV f hp rl R rl = (2.7) where: hp Rrl = horsepower required to overcome rolling resistance (hp) V = vehicle speed (ft/s) f rl = coefficient of rolling resistance (unitless) W = vehicle weight (lb)...
View Full Document

This note was uploaded on 02/04/2009 for the course CE 321 taught by Professor Petrucha during the Fall '02 term at Penn State.

Page1 / 7

Chapter_2_Equations - THE PENNSYLVANIA STATE UNIVERSITY...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online