Engineering in Sports

Alex Friess Ph.D. Emera Astronomy Center March 21 2019 Images: Wikimedia commons and ISEA Definition by ISEA:

“Sports engineering is the technical application of mathematics and physics to solve sporting problems”

• Difference between Sport Science and Sports Engineering: • sport scientist is interested what is going on inside the athlete – how much oxygen they are using, which muscles are working the most etc. whereas as • sports engineers are interested in the external factors – i.e. how the athlete may interact with the equipment or the environment

ISEA: International Sports Engineering Association, http://www.sportsengineering.org/ Outline

• Background on me • Examples: • Cycling • Baseball • Golf • Speeds Skiing • Americas Cup Sailing How did I end up doing Sports Engineering? • Education: • BSc Physics • MSc and PhD in Aeronautical Engineering • Currently do • MEE professor UMaine • Teach Aircraft Design and Capstone Class • Sports Engineering Projects Sports Engineering in Capstone

• Human Powered Vehicle • Hydrofoiling water bikes • Smart swimming starting blocks How did I get into Sports Engineering? Direct SE research/industry Involvement: • Speed Skiing (US Speed Skiing Team) • Sailing • America’s Cup Team Shosholoza (2004-2005) • World Sail Speed Record consulting (2000) • Editorial Board member Journal of Sports Engineering Some things have changed …

Tour de France 1902

Material: Steel Weight: 18 kg (40 lb) Gear: none

https://roadcyclinguk.com/gear/bikes-tour-de-france-brief-history-race-winning-machines.html 2016 Tour de France

Material: HM Carbon Weight: 6.8 kg (15 lb) Frame weight: 0.86 kg Gears: 20-22

https://roadcyclinguk.com/gear/uci-worldtour-2016-bikes-team-skys-pinarello-dogma-f8.html 2016 Tour de France TT

https://cyclingtips.com/2015/07/tour-de-france-tech-tt-bikes-helmets-and-more/ Aerospace engineering in bikes

https://cyclingtips.com/2018/01/how-carbon-fibre-bicycle-frames-are-made/ Aerospace Engineering in bikes

Image: Wikimedia commons Aerospace Engineering in bikes

Taraborrelli, L., Grant, R., Sullivan, M. et al. Sports Eng (2019) 22: 11. https://doi.org/10.1007/s12283-019-0303-8 Helmet and headgear testing

Professor Vincent Caccesse, University of Maine Average speed over the years

https://en.wikipedia.org/wiki/Tour_de_France_records_and_statistics Cycling Aerodynamics

• At 50 km/h aerodynamic drag is about 90% of total resistance • Time gains over 40 km: • Aero frame = 14 sec • TT helmet = 67 sec • Aero wheels = 71 sec • Aerobars = 122 sec

• Skinsuit = 134 sec Wikimedia commons

• TOTAL = 6.8 minutes!!!

From Alexander Spoelstra, TU Delft (http://www.sportsengineering.org/category/general-news/) Some things have not changed …. Or have they?

Images: Wikimedia commons Baseball

2-7/8in to 3in diameter 5- 5 ¼ oz

• Fastest MLB fastball: • Aroldis Chapman, 105.1 mph (2010) • Kinetic Energy of 164 J

KE of .22 LR rifle bullet (muzzle speed of 1252 fps) is only 130 J !!!

Images: Wikimedia commons Bat impact and break references

• https://youtu.be/QFlEIybC7rU (Baseball Impact video) • https://youtu.be/GD_0PQVPZmI (broken bats video)

Images: Wikimedia commons What can engineers do?

• Cannot slow the sport down … • Need to make bats safer Engineering Bat Safety • Bat testing and certification • UMass Lowell • Washington State Sports Science Laboratory

http://memagazineselect.asmedigitalcollection.asme.org/mobile/article.aspx?articleid=2682283 Engineering Bat Safety https://youtu.be/QFlEIybC 7rU Time Warp at Discovery HD

http://memagazineselect.asmedigitalcollection.asme.org/mobile/article.aspx?articleid= 2682283 Some conclusions MLB certification changes 2009 • Grain angle dependence (certification) – ink spot and 1:20 slope of grain • Impact zone sensitivity (sweet spot) • Bat performance safety • Clear bats only

http://www.woodbat.org/ Some things have not changed …. Or have they?

Images: Wikimedia commons Golfballs

Featherie, John Gourlay, about 1786 193 yards

http://www.scottishgolfhistory.org/origin-of-golf-terms/golf-ball-feathery-gutty-haskell/ https://www.core77.com/posts/25240/A-Brief-History-of-Golf-Ball-Design-and-Why-You-Shouldnt-Hit-People-with-Baseball-Bats Golfballs

Gutty, Dr. Paterson, about 1848 (first smooth, but worked better when scratched)

Haskell, 1902 - 1967

Fastest speed: 217 mph Longest drive: 514 yards

https://www.core77.com/posts/25240/A-Brief-History-of-Golf-Ball-Design-and-Why-You-Shouldnt-Hit-People-with-Baseball-Bats FIG. 1. Variations of the drag coefficient for smooth and dimpled spheres with the Reynolds number, together with the present result from a half-dimpled sphere.

Aerodynamic characteristics and flow pattern of a golf ball with rotation by Aoki, Katsumi; Muto, Koji; Okanaga, Hiroo https://blogs.unimelb.edu.au/sciencecomm Procedia Engineering, 06/2010, Volume 2, Issue 2 unication/2013/09/27/smooth-vs-dimpled- balls/ Conclusion

• Dimples: • Change BL to turbulent • Increase skin friction drag • Decrease form drag • Stabilize wake • Increase lift

The Influence of Golf Ball Dimples on Aerodynamic Characteristics Takeshi Naruo Taketo Mizota Procedia Engineering Volume 72, 2014, Pages 780-785 Speed skiing research

Results

Americas Cup The America´s Cup

• Tradition – oldest trophy in sports • History: 1851 100 Guineas Cup • Isle of Wight • Trouble (1987, 2007) • Competition • NYYC Deed of Gift (G. Schuyler, 1857) • Defender vs Challenger • Match racing • Technology • Designer´s race (i.e. Australia II, 1983) • Rule governed yachts (J Class, 12m, IACC) • MONEY!!! AC history

Stars & Stripes, 1983 12m 1851- America

Reliance, 1903

USA17 2007 D.O.G. Match IACC 2007 - Shosholoza AC45 34AC 2013 The AC Racecourse Wind Order of Actual yacht´s Mark Roundings Track for first lap

Downwind

Upwind

Distance between marks around 3-6 NM The problem at hand

To complete the racecourse faster than the competition … “your Majesty, there is no second “ • Tactics – Match Racing (afterguard) • Boat Handling – crew work • Speed – Design advantage: • VMG (Velocity made good) • High Velocity through the water • Low Angle to the wind (upwind) How to minimize the Angle to the wind? Aero and Hydro Efficiency

In order to minimze the angle to the wind that the yacht can attain, both aeroynamic and hydrodynamic Lift to Drag ratios (efficiencies) need to be maximized. L/D Example – Evolution of sail planform

One Australia 1995 cup Young America 2000 cup LR ITA94 2007 cup

AC72 – wing sail catamaran Maximize stability to increase V Ability to carry as much sail area as possible

Driving force Fx is component of overall Aero Force Fa • Maximize Fa

• Increase Form stability* (make boat wider) Fa • Has adverse effect of increasing the drag (friction) • Increase Weight stability (lower CG) • Has no adverse effect – requires high degree of STRUCTURAL optimization

*Often rules do not allow this Classic example of efforts at lowering CG Australia II, 1983

“traditional” 12 m keel shape

Australia II inverted winged keel

https://en.wikipedia.org/wiki/Winged_keel#/media/File:Australia_II_winged_keel.JPG From yacht physics to practical naval architecture

Yacht designers need to explore the design space, and test alternatives and their relative potential

• A simulator, much like a flight simulator, is required

• Takes physical model of the yacht and applies aero and hydro forces for all desired wind and heading conditions

• Allows virtually racing the yacht for given course and weather conditions against competing designs (parametric studies)

VPP – Velocity Prediction Program VPP Output: “Velocity Polars” velocity at all points of sail and for the chosen wind speed range

IACC sample polars Example –Hull and appendages •Panel method – “first pass”

•RANS CFD full hull and appendages

•Drag at all points of sail

•Individual RANS appendage optimization

•Calibrate with appropriate tank testing (up to 1/3 scale)

•Sail VLM

•Sail RANS How to increase weight stability?

• Optimize the structural design to achieve a low CG (structure as light as possible, concentrating all the weight in the keel bulb) • Need detailed prediction of structural loads • Need detailed prediction of aero and hydrodynamic forces Some typical areas of application

Panel method: wave pattern RANS CFD: Deck aerodyanmics

Tow Tank – Wavemaking Drag

RANS CFD: Keel&Bulb

RANS CFD: Bulb optimization Wind Tunnel: Keel&Bulb/Sails Present and future

AC72 and AC 50 foiling catamarans Top speed 47.2 kts Some Americas Cup reference videos • https://www.sail- world.com/news/212034/American-Magic-show- off-AC75-test-boat--Video • https://youtu.be/8Yau9A7XDHs