282

INDEX

Aacceleration, force for, 3-4Ackermann geometry, 140-141aerodynamic drag, significance of,

1-6aerodynamic drag components, 6-

9aerodynamic drag equation, 1-3aerodynamic drag measurements,

249-253direct measurement of, 253indirect measurement of, 251-

253aerodynamic moments, 128-132

pitching moment, 131-132yaw and roll moments, 128-131

AeroVironment solar bike, 128AeroVironment think tank, 256air density, 1air velocity. See velocityair viscosity. See fluid viscosityairflow. See flowairfoils. See also NACA; stream-

lined body; 2-D airfoils; XFOIL programground effect on drag, 119leading-edge (LE) separation, 64low drag solar cars, 7-8perturbances near leading edge

of, 48-50in planview, xii-xiiisupervelocity effect, 79thinness of, and Cp slope, 45very low ground clearance, 126-

128AIRSET program, 104, 105altitude, 23angle-of-attack, 226

lift reduction and, 119, 134models, 223for vehicle testing, 237, 238for zero lift, 121

animals

aerodynamic motive efficiency of, 73

denticles, 66-67appendages, 255. See also cano-

pies; fairingsangle with body in front view,

149-150drag of, 220fillet radius along side of, 150-

151junctions, 147-158, 268

APS Solar/Electric 500, 1991, 15atmospheric pressure, 1attached air/fluid flow, 7attachment-line contamination,

52average skin-friction coefficient

Cf. See total skin-friction coeffi-cient Cf

Awet. See wetted areaaxisymmetric teardrop body (tor-

pedo), xi-xii, 10, 56axles, lift imbalance between

front and rear, 131-132Aztec College 1995 Pure Energy,

190

Bbase area (flow separation), 10, 11battery ventilation, 210, 212-213bellypan, 226, 228

fairings mounted to, 149-150ground clearance of, 116-119,

126laminar flow and, 116-117, 131,

196-197, 199, 264, 268lift and, 136, 220optimal flow for, 65sanding of, 248seals, 175-183, 208supervelocity on, 2183-D relieving effect and, 104

wheel openings in, for wheel steer, 160-164

Bernoulli, Daniel, 25Bernoulli Equation, 2Bernoulli’s Principle, 106bicycle wheels, testing of, 158-160Biel cars, 90, 230Biel cars 1990 Spirit of Biel-

Bienne II, xv, 17, 116, 170, 266 canopy, 184

crosswind drag and, 142-143surface smoothness of, 199, 249

Biel cars 1993 Spirit of Biel-Bienne III, 170, 193, 249, 266-267crosswind drag reduction, 138-

139, 142-143TFT model compared, 97-99,

218trailing edge, 116wheel fairings, 175-178

Biel cars 1995 design, 30bluff bodies, 7, 10, 255

drag proportional to frontal area, 11

negative pressure and, 43body generating lift, 8-9body thickness

maximum, 268model, 219streamlined body drag of, effect

on, 78-79boundary layer, 27-67. See also

laminar flow; shape factor H; turbulent flowCd and, 13cross-flow effect, 44, 52-56definition, 25, 28design and development issues,

64-67duct placement and, 211flat plate, plotting thickness

over, 34-35

INDEX 283

friction, 37-41introduction to, 27-30junctions, flowing into, 156-157momentum-flow dissipated by,

33non-flat streamlined body, thick-

ness over, 35-37pressure drag, 79, 88pressure inside, 224separation, 33, 59-64superlayer, 31surface perturbances, effect on

transition of, 46-50thickness, 24, 31-37transition location (See bound-

ary layer transition location)viscous friction and, 7-8wheel openings and, 160-164

boundary layer transition loca-tion, 30, 41-59, 62, 63, 74, 77-78, 220canopy and, 185-188models, testing of, 223narrow cars, 99shear-fluid tests, 246-2472-D airfoil drag-calculation

results, 82-83, 853-D body drag-calculation

results, 94-95, 97brake signals, 202bubble canopies. See canopiesbugs, removal of, 51-52

CCal-Poly Pomona 1995 car, 179,

181Cal-State LA 1993 car, 262camber, xi-xii, 114-121, 268

definition, 106-107in free air, 107

canopies, xii, 89, 136, 183-196, 227-229, 268camber effects and, 119design concepts, 185-186elimination of, 147-148flow separation and, 60-61, 64,

190hatch seams, 204, 207introduction, 183-191junctions, 185, 196, 230, 262,

268length-to-height ratio L/h, 192-

194location on car, 192narrow cars, 99optimal flow for, 65sail effect and, 142-143

sealing of, 237shape changes, effect on drag of,

194-196on short cars, 184-185, 189, 260-

267truncation at rear of, 10variables, 191-196yarn-tuft tests, 241-242

catamarans, 155-156, 160-161, 169-170, 179, 185, 203

CD. See drag coefficient (CD)center-of-gravity CG, 128-131center-of-pressure CP, 128-131chordwise velocity, 52-53circular leading edge, 54Clarkson University

1995 Helios, 14-15, 97, 117, 139-141, 179, 198, 218, 231

1997 Solar Knight, 117, 198, 231coefficient-of-pressure (Cp), 60,

63, 88-89, 153plots, 43-45, 62, 104-105, 197-

198, 223, 224-231, 268shape of curves, 226

combination bodies, xiicomputational fluid dynamics

(CFD), 102, 120-121, 135models, testing of, 222-223plots, 224-232

concave surfaces, 50, 231cone tail, 87-89, 203corner flow, 56-57crabbing, 139-140cross-flow, 44, 52-56, 77crosswinds, 103, 114-115, 132-

144, 255drag reduction, 137-144lateral edge shape and, 122-123lift and, 105, 132-137, 136-137,

263sharp nose in, 154-155trailing edge design and, 203yaw stability and, 128-131

Crowder College1990 2-seater, 1851984 TSAR, xiv

DDaedalus human-powered air-

craft, 212D’Alembert, Jean, 25, 219, 232denticles, 66-67development. See testing and

developmentDexter-Hysol Cheetah, xiii-xivdisplacement thickness δ *

(boundary layer), 31-33, 46, 47

distortion, rate of, 23downwash, 114draft, 58, 173drag area (CdA), 2, 9-17

comparisons of, 15flat plate transition point, 78model vehicle, 217-218NACA ducts, 211non-lifting 3-D streamlined

body, 101power data, estimation from,

253-254sharpened nose and, 56solar-viscosity ratio, 16-173-D body, 95-982-D airfoil drag-calculation

results, 85-86wind-averaged, 253

drag coefficient (Cd). See also drag area (CdA)boundary layer management

and, 13canopy, 194-195flat plate (Cf), 73-77, 79, 80reference area, coupled with, 1, 2rotationally symmetric body

(torpedo), 87of streamlined bodies, 69-73torpedo with a flat tail (TFT

body) drag-calculation results, 94-95

2-D and 3-D bodies compared, 103, 105

volume to the two-thirds power, based on, 12

whole body, drag of (Cd, plan), 79-84

drag forceskin-friction (See skin friction)total, 3 (See also aerodynamic

drag; rolling resistance)drag index. See drag area (CdA)driver, ventilation for, 210, 213drivetrain efficiency, 3ducts, inlet and exhaust, 209-216dynamic pressure, 2

Eearly car design, xiveffective body shape, 31Electrathon cars, ix, xiii, 119, 128electric vehicles, ix, 117. See also

General Motors ImpactRumpler design, xiiitruncation, effect of, 10-11

ellipses, 91-92Euler, Leonhard, 25

284 IN D EX

Ffairings, 13-15, 18, 224. See also

wheel fairingsdefinition, 13-14fillets, 230gaps and seams, 204half-fairings compared to full

fairings, 179-181leading edge designs, 153-154stability, effect on, 238-239winglets, 126

fastbacks, xii, 118fillets, 230

leading edge, 152-155radius along side of appendage,

150-151trailing-edge, 158

flat platedrag calculation results, 73-78model, 219plotting boundary layer thick-

ness over, 34-35flat spots, detection of, 51flat tail, 87. See also torpedo with

a flat tail (TFT body)flow

distortion, 64inviscid, 27, 28, 31

flow separation, xv, 7-8, 59-64, 152, 268. See also pressure dragavoiding, 10body thickness and, 79flow distortion, 64at front of body-appendage junc-

tion, 60-61lateral-edge shaping and, 103leading-edge separation, 64local separation, 64minimizing, 60at rear of body, 61-64shear-fluid tests, 249turbulent separation, 61-62yarn-tuft tests, 241-242

fluid density, 21-23aerodynamic drag, effect on, 1altitude, effect of, 23humidity, effect of, 22

Fluid Dynamic Drag, viifluid kinetic energy, 2fluid mechanics fundamentals,

21-27fluid viscosity, 7, 23-25. See also

boundary layerdynamic viscosity and tempera-

ture, 24history, 24-25inviscid air flow and, 27, 28, 31no-slip condition, 28-29

rate of distortion, 23shear rate, 23-24

force (Newtons), 3Ford of Australia

1993 Aurora, 1301996 Aurora 101, 117, 130, 149,

156, 179, 199, 205, 231form drag. See pressure dragfour wheelers

center-of-pressure and, 129-130chassis configuration, 173-175wheel drag compared to three

wheelers, 169-175free air, lift in, 105-109freestream

body-contour angles and flow of, 61

turbulence, 58-59velocity, 54

frontal areaas Cd reference area, 2, 10, 11narrow cars, 100streamlined bodies, 13-14, 69-712-D airfoil drag-calculation

results, 84-85, 86-873-D body, 96-97

fuel-economy-record cars, ixFusion human-powered vehicle,

198

Ggaps, 204-208, 237, 268General Motors Impact 1990 EV1

prototype, 4, 11, 303General Motors Sunraycer

ducts in, 210-211empirical drag equations, 87, 88laminar flow and, 55, 204lateral edges, 122lift of, 112, 125nose shape and canopy of, 199rudders at tail of, 130sailing thrust of, 142, 199surface perturbances on nose of,

48unibody shape, 147, 170vent inlet, 213

General Motors Sunraycer 1987, xiv-xv, 4, 17, 99, 218, 226, 256-257Awet/2D plan ratio, 102crosswind lift, 133-135lift of, 115nose of, 54, 90, 197separation of, 64solar array, boundary layer

thickness over, 207

trailing edge of, 201-202wheel design, 159wheel drag, 169, 171wheel openings, 160-162

GM Sunraycer Case History, viiground clearance, 114-121, 226,

268minimum, 118very low, 126-128

ground effect, 105-128, 220, 226camber and ground clearance of

land vehicles, 114-121induced drag, 109-114, 124-126lateral-edge shaping, 121-124lift in free air and in proximity of

ground, 105-109rolling resistance and, 124-126very low ground clearance, 126-

128

Hhalf-fairings, 164-169, 179-181head wind

pitching and, 131velocity relative to road (Vwind),

1, 2heat-shrink film, 209, 247-248Heliotrope, 1996 (France), 170Hibbs, Bart, viihigh spots, detection of, 50history of streamlined land vehi-

cles, xi-xviHoerner, S. F., viiHonda 1990 CRX, 203Honda 1990 Dream, 14, 180, 257-

258crosswinds effects, 136vent inlets, 213wheel openings, 160-162

Honda 1993 Dream, 14, 15, 17, 258-260crosswinds effects, 136drag area, 218vent inlet, 213wetted area, 73wheel openings, 161-162

Honda 1996 Dream, 17, 259bellypan, 175crosswind effects, 136fairings, 178leading edge junction geometry,

152, 155lift of axles, 132models, 259seals, 210trailing edge junction geometry,

158

INDEX 285

wheel drag, 169wheel openings, 163, 169wheel well housing, 182winglets, 126yaw of, 143

Honda Motor Company wind tun-nel tests, 171

Hooke’s Law, 23horseshoe vortex, 108-109, 152-

155, 195, 230-231Huber, Chris, xiiihuman-powered aircraft, 212human-powered vehicles (HPVs),

ix, 119, 128200 meter land-speed record,

xiii-xivRumpler design, xiiitrial-and-error design, xiii

humidity, 22hybrid electric vehicles, ixhysteresis losses, 4, 6

IIdeal Gas Law, 22indicator lights, in trailing edge,

202induced drag (Dind), 6, 8-9, 109-

114, 121, 124-126. See also vor-tex shedding

interference drag (Dint), 6, 9, 64, 147-158, 185, 220

inviscid flow, 27, 28, 31

JJaray and Klemperer, xi-xii, 114junctions

angle between appendage and body in front view, 149-150

canopy, 185, 196, 230, 262, 268drag at, 262, 268flows, 147-158leading-edge geometry, 152-157minimizing number of, 147-148negative drag increments, 148solar array and body, 208trailing-edge junction geometry,

157-158wheel fairings, 228

Kkinetic energy per unit volume, 2Klemperer. See Jaray and Klem-

pererKonig-Fachsenfeld, xii

LLake Tuggeranong College, 156laminar flow (boundary layer), 30-

37, 79, 228-229bellypan and, 116-117, 131, 196-

197, 199, 264, 268Biel-type body, 230concave surfaces and, 50corner flow and, 57flat plate, plotting layer thick-

ness over, 34-35junction geometry and, 156-157lateral-edge shaping and, 103models, testing for, 223Morelli body, 231negative pressure gradient and

laminar flow, 45-46nose shape and, 44, 196-199, 268nose-sweep angles and, 54-56optimal amount, determining,

64-65seams and, 204-205separation at rear of body and,

63-64shear-fluid tests, 232-236, 245-

249skin friction coefficients, 37-41skin friction reduction and, 64,

72supervelocity effect, 78surface fairness and, 50-52surface finish and, 29, 208-209,

223torpedo with a flat tail (TFT

body) drag-calculation results, 95, 97

transition to turbulent flow (See boundary layer transition loca-tion)

2-D airfoil drag-calculation results, 83-84, 86-87

laminar sublayer, 30-31land-speed-record vehicles, ix, 128lateral edges

crosswinds and, 122-123height of, and lift, 115induced drag, effect on, 121shaping, 103, 121-124wetted area, 123

leading edgeboundary layer at, 28, 34circular, 54junction geometry, 152-157optimal flow for, 65perturbances near, 48-50separation, 64sharpness at junction, 154-155swept, cross-flow due to, 53

LED light, 202Lexan, 189-190lift, xv, 8-9

crosswinds and (See crosswinds)elimination of, 220in free air and in proximity of

ground, 105-109horseshoe vortex and, 108-109minimizing, 263, 268uneven, on front and rear

wheels, 105line-of-sight, 121Lissaman, Peter, vii, 105local Reynolds numbers (Rex), 26,

35 laminar state for, 46

surface perturbances based on, 47-48

local separation, 8, 64local skin-friction coefficient Ct,

35, 37-41local velocity, 24low spots, detection of, 50-51

Mmaintenance of surface, 51-52Mana La car, 1987, 137, 139mass-acceleration effect, 3-4Messiah College 1997 Genesis

solar car, 90MIT, 152. See also XFOIL pro-

gramAPS Solar/Electric 500 design,

15Aztec, xii, 97, 118, 198, 203, 231,

239electric car, 117Galaxy, xv, 99, 184-185, 188-189,

260-261shear-fluid tests, 59wheel-fairing wind tunnel study,

164-169MIT 1995 Manta, xv, 14-15, 17,

218camber and lift, 112, 120, 124-

125canopy, 185, 189-190chassis testing, 236-237Cp curves, 226cross-flow instability, 55-56crosswind lift, 135drag of, 99empirical drag equations, 87-89goals of, 262-264junction flows, 148lateral edges, 123nose shape, 197-198, 199

286 IN D EX

separation at rear of body, 63, 64solar array, 206surface smoothness, 29-303-D relieving effect, 104ventilation, 210wetted area, 73, 89-90wheel housings, 182wheel openings, 136, 160yarn-tuft tests, 240-241

MIT 1997 Manta GT, 14, 15, 17, 102, 218-219, 223, 264-265bellypan, 228boundary layer thickness over,

36camber and lift, 120, 123, 124canopy, 189, 207, 227-229Cp curves, 226, 227Cp plot of, 227-229cross-flow instability, 56crosswind lift, 136fairings, 155, 180, 239indirect aerodynamic drag mea-

surements, 253laminar flow, 228-229nose shape, 228separation at rear of body, 64shape-factor plots, 231solar array, 2063-D relieving effect, 105ventilation, 210, 213wetted area, 73, 89wheel housings, 182wheel openings, 163yarn-tuft tests, 240-241

MIT 1998 Manta GT, 17shear tests, 246, 249yarn-tuft tests, 241

Mitsubishi Materials 1996 Sun Challenger, 180, 190

model vehicleconstruction of, 217-221outline, 219-221

momentum thickness Q (bound-ary layer), 31-35

momentum-flow dissipated by boundary layer, 33

Morelli body, xii, 117-118, 198, 231ground effect on drag, 119tail truncation and, 203TFT model compared, 97, 99

Mylar, 209

NNACA 7 airfoil, 86NACA 66 airfoil, 44, 62, 80NACA 006 airfoil, 102

NACA 0010 airfoil, 44, 102NACA 0012 airfoil, 49NACA 0015 airfoil, 102, 127-128NACA 4412 airfoil, 128NACA ducts, 210-212narrow cars, 77, 99-101Nissan

1990 Hoxan, 56, 179, 1811993 Sunfavor, 64, 123-124, 171

Northern Essex Community Col-lege 1995 TNE-3, 15, 63, 128

Northern Territory University (Australia) 1996 Desert Rose, 150, 158, 177, 198, 242, 252

nose, 196-200, 228airfoil thinness and Cp slope, 45boundary layer thickness and,

47canopy, bluntness of, 195crosswinds, wrap for, 103ducts, 212favourable pressure gradient,

42-43laminar flow and, 44, 268lateral edges and, 122-123optimal flow for, 65radius of, and cross flow, 53-55rounded, 44, 77, 90sharp, 77, 154-155smoothness, maintenance of, 51-

52surface perturbances on, 29-30,

48, 249wetted area, reduction of, 77

nose-sweep angles, 54-56nose-up/nose-down pitch, 131-

132, 237no-slip condition, 28-29, 52

Ppitching moment, 105, 131-132planform area. See planview areaplanview

airfoils in, xiirounding of nose in, 44sharpened nose in, 56short cars, 90solar-array areas, 16tail shape, 194very curved nose in, 52

planview area, 12, 14-15comparisons of, 15narrow cars, 99-100streamlining examples, 69-70

potential flow. See inviscid flowpower, 3power test, 251, 253-254

Prandtl, Ludwig, 25pressure drag, 6-7, 9, 11, 37, 64

boundary layer (Dpres,BL), 8, 79, 88

horseshoe vortex, caused by, 152streamlining to minimize, 69

pressure gradient, 224adverse, 45-46, 59-60, 65, 152,

153, 185-186, 197, 231boundary layer thickness and,

36favourable, 42-43, 45-46, 48, 65,

228negative, 52, 65positive, 198

pressure-recovery region, 43profile drag, 8pure electric vehicles, ixpushing, 173

QQUADPAN program, 43, 102, 104,

222, 224-225Queens University

1997 Dawn Treader, 901995 team, 64

Rrear body and lift reduction, 137rear-wheel steering, 139-140reference area A. See also drag

area (CdA); frontal area; plan-view area; wetted areadrag coefficient, coupled with, 1,

2streamlined body, 11-14

Reynolds, Osborne, 25Reynolds number (Re), 25-27,

220, 223aft-body separation, 64canopy drag coefficient, 194cross-flow instability, 53derivation of, 26-27drag experiments at high num-

bers, 1flat-plate drag calculation, 73-78laminar boundary layer and, 46local Re (Rex) (See local Rey-

nolds numbers (Rex))minimizing pressure drag at

running, 69, 71-72torpedo with a flat tail (TFT

body) drag-calculation results, 94

INDEX 287

total plate length Re (ReL), 26, 35

2-D body affected by, 82riblets, 57, 65-67robustness studies of body shapes,

224roll axis, 130-132rolling resistance, 3-6, 124-126

coefficient (Crr), 5-6vehicle mass and, 18-19

rotationally symmetric body (tor-pedo), 87-89

rounded body, volume-to-Awet ratio of, 102-103

rudders, 130Rumpler vehicle, xii-xiii

Ssail battens, 51sailing land vehicles, 9, 137-144,

242sailplane study, 153-154sanding, 50-51, 200, 248Santa Cruz 1996 Pumpkin Seed,

139, 242seals. See also seams

bellypan, 175-183, 208canopy, 237Honda 1996 Dream, 210vent hole, resealable, 213wheel wells, 180-181, 204, 208,

224, 237, 264seams, 64, 204-208, 237, 268separation pressure drag. See

pressure dragshape factor H (boundary layer),

33, 61-63, 231-232shear rate, 23-24, 28, 30, 77, 200shear stress, 24, 29, 37, 59, 231shear-fluid tests, 59

on-road testing, 245-249wind tunnel tests, 232-236

shearing action, 7, 8shear-stress coefficient. See local

skin-friction coefficient CτShell Marathon vehicles, 128short cars, 55-56, 90, 129-130,

184-185, 230, 260-267center of pressure and center of

gravity, 129-130nose shape, 197-1993-D body, example of, 95-97

skin friction (Dskin), 7-9, 25, 37, 64, 85, 219drag (Df), 24, 37-40, 64-67, 71,

72

laminar and turbulent flow and, 30, 72

separation and, 7supervelocity effect, 78-79, 219-

220surface roughness, effect of, 208-

209skin-friction coefficient

flat plate (Cf), 73-77, 79, 80, 220in junction, 152local (Ct), 35, 37-41total, 37-38

solar array, 99, 255, 268application of cells, 222cooling of, 227-228gaps and seams, 204-208heat-shrink film to smooth

surace of, 209optimal flow for, 65placement of, 263, 264in short cars, 184, 185Sunrayce rules, 99

solar bikes, ix, xiii, 128solar-viscosity ratio, 16-17, 268Solectria-4, pre-1987, 255-256Solectria BRLS-8, 213Solectria Flash, 1992, 203South Dakota School of Mines and

Technology 1995 car, 170spheres, 72spined aftbody, 135-136spoke covers, 134stability during testing, 238-239Stanford University

1995 Afterburner I, 1791996 Afterburner II, 64, 192-93,

241-2421997 Afterburner III, 179, 189

steps, forward or backward, 207-208

stiffness of body, 222Stratford Criteria, 64streamlined body, 8

body thickness, effect on drag of, 78-79

boundary layer thickness over, 35-37

construction of simple model of, 217-221

examples of, 69-73reference area, 11-14skin drag reduction, 65successful, 255-267surface temperature, effect on

drag of, 57-58TFT model, verification of, 97-99 3-D bodies, empirical drag

equations for, 87-97

3-D bodies, examples of drag of, 99-101

2-D airfoils, empirical drag equa-tions for, 80-87

2-D vs. 3-D bodies, 101-105Sunrayce. See also specific vehi-

cles1990, 184-1851997, 185four wheelers in, 169rules, 99

superlayer, 31supervelocity, 78-79, 87-88, 103,

107on bellypan, 218skin friction, effect on, 219-2203-D relieving effect, 104

surfacefairness, 50-52maintenance of, 51-52perturbances, 29-30, 46-50, 88-

89, 204, 249roughness/smoothness, 199-200,

208-209, 223, 246temperature, effect on drag of,

57-58texture, 50-52

suspensionkinematics and pitching, 131-

132motorcycle-strut type, 179for testing, 238

swept leading edge, 53

Ttail cone, 87-89, 203tail incidence, 119tail truncation, 10-11, 203. See

also bluff bodies; short carstail wind, 1tandem wheel assemblies, 171-174tangential fluid molecules, shear-

ing of, 7TASCFlow models, 137teardrop. See axisymmetric tear-

drop body (torpedo)testing and development, 222-254.

See also shear-fluid tests; wind tunnels; yarn-tuft testsof actual car, 236-254aerodynamic drag measure-

ments, 249-253CFD plots, 224-232outline of development cycle,

222-224power test, 251, 253-254

288 IN D EX

successful streamlined bodies, 255-267

vehicle stability, 238-239texture, surface, 50-52

TFT body. See torpedo with a flat tail (TFT body)

three wheelers, 255center-of-pressure and, 129-130chassis configuration, 173-175wheel drag compared to four-

wheelers, 169-1753-D body portion, 633-D relieving effect, 104-1053-D streamlined bodies

drag area (CdA) of non-lifting, 101

empirical drag equations for, 87-97

examples of drag, 99-101two-dimensional vs., 100-105wetted area of, 89-94

tires, 130relieving weight on, 124rolling resistance and, 4-6scrubbing, 140-141stability, effect on, 238testing size, 238

Tollmien-Schlicting waves (T-S waves), 34, 42, 45, 46, 59

top view. See planviewtorpedo with a flat tail (TFT

body), 87, 88, 217-2213-D body drag-calculation

results, 94-97verification of model, 97-99

torpedo-shaped body, 255. See also axisymmetric teardrop body (torpedo);

rotationally symmetric body (tor-pedo)ground effect on drag, 119solar race cars, xivvery low ground clearance, 128

total drag force, 3total expended power, 3total plate length Reynolds num-

ber (ReL), 26, 35total skin-friction coefficient Cf,

37-38Tour de Sol, 3trailing edge, 226

angle, and lift, 116of bellypan, 117crosswinds, design to reduce

drag in, 203horseshoe vortex beyond, 152indicator lights in, 202junction geometry, 157-158shape factor H curve and, 232

thickness of, 200-203turbulent boundary layer at, 79

truncation, 10-11, 203. See also bluff bodies; short cars

turbulent flow (boundary layer), 30-37, 61-62, 65to cool solar array, 227-228 cor-

ner flow and, 57duct placement and, 211flat plate, plotting layer thick-

ness over, 34-35flat-plate drag calculation, 77freestream turbulence, 58-59lateral-edge shaping and, 103nose shape and, 197-198separation at rear of body and,

63-64shear-fluid tests, 232-236, 245-

249skin friction coefficients, 37-41supervelocity effect, 78surface finish and, 29, 208-209at trailing edge, 79transition from laminar layers,

41-59turbulent wedges, 246turn-signal lights, 2022-D airfoils (streamlined bodies)

Cp plots for, 43empirical drag equations for, 80-

87lift in, 115reducing drag of, 86-873-D vs., 100-105wetted area, 102, 103

2-D body portion, 63

Uunibody super streamliner, 256-

257University of Maryland 1990

Pride of Maryland, 132, 135-136, 142, 150, 161-162, 226, 229-230

University of Michigan1990 Sunrunner, 16-17, 132,

161-162, 169-170, 179, 2031993 Maize & Blue, 16-17, 1691995 team, 1261997 Wolverine, 120, 143, 190,

230University of Minnesota

1995 Aurora 2, 80, 105, 116, 160, 205, 210, 213

1997 Aurora 3, 103, 105, 116, 175, 202, 205, 210, 213

University of Queensland (Aus-tralia) 1996 team, 176

University of Waterloo (Canada)1990 Midnight Sun, xv, 99, 136,

144, 179, 184, 2611997 Midnight Sun IV, 137, 144,

148, 177, 179, 186-188, 226, 230-231, 265

Vvehicle mass, tradeoff with aero-

dynamic drag of, 18-19vehicle speed

aerodynamic drag as function of, 3

fixed speed, propelling car at, 251

velocity. See also supervelocityboundary layer and, 28car relative to road (Vcar), 1curvature, velocity-pressure

relationship around, 42-43head wind velocity relative to

road (Vwind), 1, 2local, 24square of, aerodynamic drag pro-

portional to, 1velocity profile, 28

chordwise, 53in cross-flowing boundary layer,

52-53fuller, 30negative pressure gradient and,

46spanwise, 53, 110

ventilation, 207, 209-216analysis, 213-216

vent hole, resealable, 213vibration, 58-59viscous friction, 6-8volume to the two-thirds power

(Vol2/3), 12Von Karman, Theodore, 25vortex generators, 190-191vortex shedding, 25, 64, 150, 228,

268lateral-edge shaping and, 85, 103lift and, 112-113, 121nose shape and, 55wing tip drag due to, 85-86

vortices, 7. See also horseshoe vor-texinduced by lifting body, 8-9kinetic energy dumped into, 111-

112, 114separation, 59-60

VSAERO program, 223-226Awet / 2Aplan ratio, finding, 102,

105

INDEX 289

boundary-layer thickness com-parison, 36

camber and lift, 120, 122, 124canopies, design of, 186-187Cp plots, 43, 56, 60crosswind lift tests, 137ptiching moment, determina-

tion of, 132Shape H plot, 63skin-friction coefficient plot, 41

Wwake rake, 253Waseda University (Japan) 1996

Waseda II, 181weight of vehicle (W), 5-6, 255Western Ontario University 1996

team, 182-183Western Washington University

1990 Viking XX, 139-140, 170wetted area, 12, 14, 37

comparisons of, 15flat plate, 73-78lateral edges, 102, 123model, 218, 220reduction of, 65, 72, 77, 99, 262,

268rotationally symmetric body

(torpedo), 87of rounded body, 102-103sharpened nose and, 56in short cars, 184-185of solar array, 16-17spined aftbody and, 136streamlining examples, 69, 71of 2-D airfoils, 102, 103of 3-D bodies, 89-94

wheel fairings, 15, 163angle of mounting, 149-150center-of-pressure and, 130crosswinds and, 133-136, 139,

142-143examples of, 175-183flow separation and, 60-61full fairings, tests of, 164-169half-fairing configurations, tests

of, 164-169junctions, 147-148, 148, 158,

228, 268MIT wind tunnel study, 164-169optimal flow for, 65separation and, 64

wheel steerrear-wheel, 139-140

wheel openings in bellypan for, 160-164

wheel wells, sealing of, 180-181, 204, 208, 224, 237, 264

wheels. See also four wheelers; three wheelersdesign, 158-160drag of system, 158-183rear wheel placement, 171-172tandem assemblies, 171-174uneven lift on front and rear,

105wind. See also crosswind

head wind velocity relative to road (Vwind), 1, 2

pitching and head wind, 131tail wind, 1

wind-averaged drag area (Cd A), 253

windshields, 121, 189-190, 207wind tunnels

aerodynamic drag measure-ments, 249-253

crosswinds tests, 132-137, 141-142, 144

models, testing of, 222nose shape tests, 197shear-fluid tests, 232-2363-wheeler and 4-wheeler drag

compared, 171-172trailing edge thickness of main

body, testing of, 201-202ventilation system, testing of,

211wheel openings, testing of, 161-

162wheel-fairing study at MIT, 164-

169Worden, James, 255, 260World Solar Challenge, 3. See also

specific cars 1987, 137, 257

1990, 56, 1791993, 1751996, 156, 242four wheelers in, 169

XXFOIL program, 81, 104

Yyarn-tuft tests, 237, 239-245

canopies, tests of, 192-193crosswinds, effect of, 135, 137fairings, tests of, 158lateral-edge shaping, tests of,

123

separation flow, demonstration of, 8, 88, 135, 137

vortices, test for, 112-113, 121yaw, 114-115, 191, 223yaw and roll moments, 128-131yaw sweep, 132-133