# Walk On Water USD Engineering Competition Competition Information Last Saturday in February USD Pool 9 a.m. to 1 p.m.

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Walk On Water

USD Engineering Competition

Competition Information Last Saturday in February USD Pool 9 a.m. to 1 p.m.

Get Ready to have Fun in applying science and engineering

Basic Task Design a pair of shoes to allow a person to walk a winding course across a pool in the fastest time possible

Basic Rules The shoes must be mirror images of each other No propellers or motors are allowed No paddles Maximum 8 foot long

More Rules Shoes may NOT be tied together There may be no attachment above the knee The pilot must be able to easily escape (drowning is a poor choice)

Teams A team may have from 2 to 4 people One shoe pilot One team captain

Team Captain Someone responsible, able to coordinate work times and organize the team Responsible for getting the paperwork turned in on time Responsible for keeping track of costs

Shoe Pilot Able to swim Light with strong legs Competitive nature Willing to get wet Runner is often a good choice

Design Hints Think before building Measure twice, Cut Once

Basic Calculations 1 kg of water is 1 liter of volume 1 liter is 1000 cubic centimeters Each shoe should hold at LEAST 60% of the pilots mass

Shoe Design Things that float are good, things that sink are bad Plan on 20 to 30 cm of width Plan on 200 to 250 cm of length Calculate the thickness

Example - Pilot is 160 pounds 160 pounds is about 80 kg Figure roughly 2 pounds per Kilogram 30 pounds of shoes (15 pounds each) 15 kg of shoe material Total Mass to be floated: 95 Kg

Example Shoe Calculation Total mass to hold - 95 kg Call it 100 kg to be safe (this is called Being Safe Each shoe must hold 50 kg

Each Shoe Holds 50 Kg 50 Kg is 50 liters 50 liters times 1000 finds cubic centimeters 50000 cubic centimeters

Volume to hold: 50000 cm 3 Shoes will be 30 cm wide Shoes will be 200 cm long Solve for the needed thickness 50000 cm 3 / (30 cm x 200 cm) Thickness needed = 8.3 cm

How to Make Shoes MOVE Drag is your Friend, Drag is your Enemy

Moving Forward but NOT back As little drag as possible is desired to move the shoes forward As much drag as possible is desired to stop from moving backwards FLAPS are needed

Flaps Fixed - Always the same shape Vertical - flaps move back and forth Horizontal - flaps move up and down Wheeled - flaps are attached to a paddle wheel structure

Fixed Flaps Fast and easy to make and attach Do not work well - little net forward motion

Vertical Flaps Act as a keel as well as a flap Work fast, independent of gravity Hard to transport and easy to damage Complicated to make and install Needs lots of material and hinges Time consuming to make

Vertical Flaps

Horizontal Flaps Fast and easy to make and transport The more flaps, the faster the response time Might be attached with duct or cloth tape Do not use wood or light floating material May have to weight the ends for a faster response time

Little Horizontal Flaps

Big Horizontal Flaps

Paddle Wheel Seen ONCE - worked well More engineering of parts necessary System needed to prevent from turning backwards

Attaching the Pilot Find an old pair of sandals or tennis shoes Tennis shoes are less likely to cause blisters Bolt, screw or tape them in the center of the shoes from front to back and from side to side. Make sure the feet can be easily pulled from the shoes

Practicing Put the shoes in the water - make sure they float Put the pilot (force may be necessary) into the shoes Spot the pilot in case of a fall, no body part hits the concrete side of the pool

Pilot Practice Hold the pilot and make sure the shoes do not sink Allow the pilot to balance and not fall, yelling at the pilot generally does not help Throwing things at the pilot definitely does not help

More Practice Suggestions The pilot should walk around and not fall down (laughing at the pilot is not encouraged YET) When the pilot falls in, then laugh Figure out what went wrong and fix it Waiting until race day is a BAD idea to first put the shoes into practice

Now Laugh at the Pilot

Legs and Muscles If the pilot does not have strong legs, the legs will be sore at the end of the day If the pilot has strong legs, the legs will be sore at the end of the day Each person in the group should get onto the shoes at least ONCE and experience the thrill of water shoes walking.

Viking Longshoes 1998 Grand Champions

Preparing the Team

Off and Striding

Near the Finish Line

The Winners

The Winning Pilot Robert Lobbia 98

Denise Cosio 98 Robert Lobbia 98 Morgan Teachworth 98 Jessi McDonald 99

Viking Longshoes First LJHS Champion 1996

Dr. Smooth 1997 Winner

Floating Wombats Winners 1999

Little Point Walkers 2000 Winner

Little Point Walker 2 2001 Winners

Get Started as soon as possible Design first then build Have Fun!

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