Need In 2050 15% of the Earths carbon dioxide emissions will be from aircrafts (U.S. Global Change Research, 2001)$61billion has already been spent in aviation for fuel alone (Segelstein, 2008)If the drag coefficient of a car was reduced by .1 the U.S. oil consumption would decrease by 7.5%. This would save 10 billion gallons of fuel per year. (Fillipone, 1999)

Golf Ball Suspension System (GBSS) (Libii, 2005)

Purpose The purpose of this experiment is to use golf ball dimpling as a model to improve aerodynamic The purpose of this experiment is to use golf ball dimpling as a model to improve aerodynamic efficiency. This may be applied to trucks, or airplane propellers and in turn decrease fuel consumption. efficiency. This may be applied to trucks, or airplane propellers and in turn decrease fuel consumption.

Hypotheses Field TestField TestNull Hypothesis H(o)Null Hypothesis H(o)- The golf balls will all travel the same distance and have the same accuracy. - The golf balls will all travel the same distance and have the same accuracy. Alternate Hypothesis H(a)Alternate Hypothesis H(a)- The golf balls with the greatest number of dimples will travel the furthest- The golf balls with the greatest number of dimples will travel the furthestAlternate Hypothesis H(a)1- Alternate Hypothesis H(a)1- The dimpleless golf ball will be the most accurate. The dimpleless golf ball will be the most accurate. Lab TestLab TestNull Hypothesis H(o)- Null Hypothesis H(o)- The golf balls will all have the same drag force. The golf balls will all have the same drag force. Alternate Hypothesis H(a)- Alternate Hypothesis H(a)- The drag force will decrease as the numbers of dimples increase.The drag force will decrease as the numbers of dimples increase.Alternative Hypothesis H(a)- Alternative Hypothesis H(a)- The dimple characteristics of hexx, smooth, steep, and dimpleless will The dimple characteristics of hexx, smooth, steep, and dimpleless will yield progressively greater drag forces.yield progressively greater drag forces.

boojum.as.arizona.edu

www.callawaygolf.com/Global/en-GB/Innovation/GolfBallTechnology/ HEXAerodynamics.html

http://www.eng.monash.edu.au/uicee/worldtransactions/WordTransAbstractsVol5No3/23_NjockLibii15.pdf

http://pdf.aiaa.org/preview/CDReadyMAAC03_774/PV2003_3662.pdf

Drag Coefficients for Conventionally Dimpled, Hexx, and Dimpleless Sphere Bearman and Harvey (1976)

Flow Around Smooth Sphere Flow Around Dimpled Sphere

•Libi, 2005- Golf Ball Suspension System

•Kato, 2005- Steep versus dimpled sphere

•Bearman and Harvey (1976)- graph representing the drag coefficients of hexx ball, conventional ball, and smooth sphere

Smooth Dimples

Steep Dimples

Smooth vs. Steep Dimples (Kato, 2005)

Figure 1- This picture shows the possible dimpling of an airplane propeller. Although just a prototype should dimples be proved to reduce drag, they could greatly decrease fuel consumption.

Figure 3 Figure 4 Figure 5

Knowledge Base

http://www.aviation-history.com/theory/lam-flo

Literature Review

Figure 6

Figure 7

Figure 8

Figure 6 compares the smooth dimples to steep dimples. Results showed that the flow around the sphere with the smooth dimples created less drag.

Figure 7 shows the GBSS inside a wind tunnel. As the wind starts to flow the ball creates an angle with the protractor. In the experiment a dimpled sphere was compared to a smooth sphere. The results showed that the dimpled sphere had a lower drag force.

Figure 8- The x-axis shows the initial velocity (m/s) while the y-axis shows the drag coefficient. The results of the experiment showed that at higher speeds the hexx ball has a lower drag coefficient compared to a smooth sphere, and conventionally dimpled sphere.

Drag Force=Mass*Graviy*Tan(

Figures 3, 4, and 5, all show various spheres and their resulting wakes as they travel through the air.

Boundary Layer •At low speeds laminar boundary layer is desirable

•Normally the turbulent boundary layer results in higher drag but the advantage is that airflow is increased and there is more forward momentum.

•As a result the ball resists the adverse pressure gradient much longer before it separates decreasing drag.