The Cialitron by LevTech

OPERATION 30 minutes continuous use by single operator Maximum operator payload of 200lbs Steering column mounted thrust throttle Operator adjusted lift power Standing position Dual rudder steering

SAFETY Lift power adjusted prior to mounting All motors started and checked prior to mounting Pre-operation inspection of steering and skirt integrity Protective gear to be worn Fan-blade housing Initial trials conducted with supervision and balance assistance

LIFT FAN ANALYSIS Air flow vs. rpm curves for various fan manufacturers require a 12 inch fan, 6 and 8 blades, and fixed pitch of 10-15 degrees A fan of this size needs to rotate at approximately 3600 rpm

LIFT ENGINE Air pressure and lift calculations with a fan efficiency of 70% and a motor efficiency of 85% require a 2.5HP motor The lawn mower engine is oversized by approximately 0.3HP to compensate for pressure losses in the skirt, fan, and platform assembly

THRUST ANALYSIS FORCES ON HOVERCRAFT Reynold’s #: Air Drag: Exposed surface, plate approximation: 1.1mX1.6m μk assumed to be ~ 0.04

THE GOVERNING EQUATION Newton’s 2nd Law: After solving differential eq. and taking t to gives max velocity Select a fan that satisfies the constraints

SELECTION OF FAN AND MOTOR 30’ diam. 2 blades, 6 hp, 1725 max rpm, 9500 max cfm, 13 degree pitch Eq. yields 6 max mph The important properties that affect hover speed: weight, kinetic friction, and fan volumetric flow rate and diameter

SELECTION OF THRUST ENGINE Gas engine with at least 4.5 hp Engine inefficiency: need 5.5-6 hp 6.4 hp, ¾’’ diameter shaft, 4 stroke, electric start, on/off start, choke, and throttle 16.9 L x 13 W x 13.8 H, 55 lbs

PLATFORM DIMENSIONS Dimensions for the plywood platform are 2.5’ x 6.25’ 6” extended outrigger system maintains the necessary space for all equipment and the rider Balance was a contributing factor in the sizing of the platform

BOARD DIMENSIONS

STRESS ANALYSIS Max Moment = PL/4 Max Stress MY/I = 535 PSI Yield Stress of wood = 4,350 PSI Safety Factor ~ 8

TOTAL WEIGHT

CONTROLS Rudders swing side to side by moving handlebars Rudders attached with door hinges and supported by rod Throttle cables for lift and thrust engine attached to handlebars

SKIRT DESIGN Pliable and Durable Material: Reinforced nylon from a whitewater raft Attached to outrigger and base to form semi-circle ring Reinforced holes

BUDGET *We currently have a useable engine for lift, but, since it cannot be left on the Cialitron after the final demonstration, we are looking for a permanent engine

WAIVER AND RELEASE Since our project has a notable risk of injury to the person and property of the rider, we thought it best to draft a waiver releasing Columbia University from liability for any/all injury sustained while riding the Cialitron. All members of LevTech have signed this waiver. Any person wishing to ride the Cialitron must sign a waiver.

Where do we go from here? Next Steps: starting fabrication of the parts for which we currently have materials (including the lift engine) ordering parts from McMaster et al. continuing our aggressive search for engines that fit within our budget increasing the intensity of our donation campaign

REFERENCES Baker, Russell, et al. “Solar Splash 2002 Columbia University Technical Report Boat #13.” Columbia University, 1 May 2002. Beaty, William J. “Ultra Simple Hovercraft.” Science Hobbyist. 1997 <http://www.amasci.com/amateur/hovercft.html>. 27 Jan 2005. “A Comparison of Different Hovercraft Lift, Thrust and Transmission Systems.” Airlift Hovercraft.<http://www.airlifthovercraft.com/HC%20Lift%20&%20Thrust%20Systems.htm>. 29 Jan 2005. “Episode 17: Elevator of Death, Levitation Machine.” Mythbusters. 6 Oct 2004. The Discovery Channel, 29 Jan 2005. “Hovercraft Theory.” Ben’s Hovercraft. 24 Sept 2003 <http://www.rchovercraft.com/theory.html>. 27 Jan 2005. Kurtus, Ron. “Determining the Coefficient of Friction”. School for Champions. 15 Dec 2002. 8 Feb 2005. <http://www.school-for-champions.com/science/frictioncoeff.htm>. McMaster-Carr Supply Company. 2005. 8 Feb 2005. <http://www.mcmaster.com/>. P. Ponk Aviation. “Propeller Tip Speed Calculator.” Hoverhawk. 10 Feb 2005. <http://www.hoverhawk.com/propspd.html>. Vawter, Richard. “Drag Force in a Medium.” Western Washington University. Dec 2005. 10 Feb 2005. <http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/-DragForce.html>. White, Frank M. Fluid Mechanics. Fifth Edition. New York: McGraw-Hill, 2002.