Ultralight Backcountry SkisDesign Goal

● Create a 1 kg ski (170 cm length, 90 mm waist).

Motivation● A lighter ski allows for more efficient travel in the

backcountry.● 1 kg off the foot is equivalent to 4.7-6.4 kg off the

back.[1]

● Average backcountry ski weighs 1.91 kg.[2]

[1] Study from Fjaderlatt.se[2] Data compiled from Evo.com

Binding Retention

● Lightweight core materials are inherently weak and alone cannot adequately hold binding screws.

● Custom fixtures for a straight pullout test were manufactured.

● The design specification was to exceed the ISO standard of 292 lb (6004:1991).

7075-T6 Aluminum Edges

● Standard steel edges contribute up to 15% of a ski’s total weight.

● By manufacturing custom edges made from 7075-T6 aluminum and only placing edges on the three major contact points, the ski weight was reduced by 207 grams.

● Abrasion testing was done to compare material loss between steel and aluminum edges.

● A Rockwell B hardness test was used to compare steel and aluminum edges.

Composite Layers

● Three point bending tests were used to find the stiffness of market skis.

● Finite element analysis was used to determine the correct composite layup.

● Our final pair consists of one biaxial and two uniaxial sheets of carbon fiber between the base and core with randomly oriented fiberglass mat and biaxial fiberglass below the topsheet.

Material Hardness [Rockwell B] Material Removal [mm] Contributed Weight [g]

Aluminum 87 21 106

Steel 99 51 313

Core● Balsa cores were chosen because of their low

weight, availability, and manufacturability.● Cores were CNC machined at Wasatch Ski Works.

Material Weight [g]

Aspen 480

Paulownia 298

Balsa 160

Prototype Ski

Target Stiffness

[N/m]

Predicted Stiffness

[N/m]

Actual Stiffness

[N/m]

Predicted Weight [g]

Actual Weight

[g]

Ski 1 6432 6503 6169 1254 1377

Ski 2 6432 4395 3826 1011 1103

Ski 3 6432 5429 5269 1005

Final Ski 6432 5429 1005

Special Thanks to: Craig Larsen, Scott Phillips, Mike Tate

Mat Fiberglass Poplar UHMW ABS Titanal Pull Test Result Avg [lb] Norm. ResultBinding Retaining Layers Strength/weight

1 177.9 Infinite2 X 266.7 108.13 X X 317.8 101.64 X 209.5 67.95 X X 394.6 105.36 X X X 430.4 69.37 XX 303.9 37.18 X X 392.6 59.89 X 317.8 39.6

Ski Press

● MDF was CNC cut for the mold.● Fire hose was used to make air bags to pressurize the mold.● Heat mats were used to generate camber by creating a

temperature differential.

Graphics

Andrew Forhan, Ben Grandlic, Jacob Hopkins, Jeremiah Rogers, Lauren Starck, Matt VisnovskyFaculty Advisors: Marc Calaf PhD, Kam Leang PhD

Department of Mechanical Engineering

● Graphics were custom designed by the team and printed on the lightest available industry standard topsheet material.

Takeaways● Ski manufacturing is inconsistent

and difficult at low volume.● While making 1 kg skis is possible,

performance sacrifices have to be made.● Composites as a science is still developing, therefore

prototyping is essential to the ski design process.