2OPERATION 30 minutes continuous use by single operator Maximum operator payload of 200lbsSteering column mounted thrust throttleOperator adjusted lift powerStanding positionDual rudder steering
3SAFETY Lift power adjusted prior to mounting All motors started and checked prior to mountingPre-operation inspection of steering and skirt integrityProtective gear to be wornFan-blade housingInitial trials conducted with supervision and balance assistance
4LIFT FAN ANALYSISAir flow vs. rpm curves for various fan manufacturers require a 12 inch fan, 6 and 8 blades, and fixed pitch of degreesA fan of this size needs to rotate at approximately 3600 rpm
5LIFT ENGINEAir pressure and lift calculations with a fan efficiency of 70% and a motor efficiency of 85% require a 2.5HP motorThe lawn mower engine is oversized by approximately 0.3HP to compensate for pressure losses in the skirt, fan, and platform assembly
6THRUST ANALYSIS FORCES ON HOVERCRAFT Reynold’s #:Air Drag:Exposed surface, plate approximation: 1.1mX1.6mμk assumed to be ~ 0.04
7THE GOVERNING EQUATION Newton’s 2nd Law:After solving differential eq. and taking t to gives max velocitySelect a fan that satisfies the constraints
8SELECTION OF FAN AND MOTOR 30’ diam. 2 blades, 6 hp, 1725 max rpm, 9500 max cfm, 13 degree pitchEq. yields 6 max mphThe important properties that affect hover speed: weight, kinetic friction, and fan volumetric flow rate and diameter
9SELECTION OF THRUST ENGINE Gas engine with at least 4.5 hpEngine inefficiency: need hp6.4 hp, ¾’’ diameter shaft, 4 stroke, electric start, on/off start, choke, and throttle16.9 L x 13 W x 13.8 H, 55 lbs
10PLATFORM DIMENSIONSDimensions for the plywood platform are 2.5’ x 6.25’6” extended outrigger system maintains the necessary space for all equipment and the riderBalance was a contributing factor in the sizing of the platform
14CONTROLS Rudders swing side to side by moving handlebars Rudders attached with door hinges and supported by rodThrottle cables for lift and thrust engine attached to handlebars
15SKIRT DESIGN Pliable and Durable Material: Reinforced nylon from a whitewater raftAttached to outrigger and base to form semi-circle ringReinforced holes
16BUDGET*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
17WAIVER AND RELEASESince 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.
18Where 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 budgetincreasing the intensity of our donation campaign
19REFERENCESBaker, 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 <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 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 Feb <http://www.school-for-champions.com/science/frictioncoeff.htm>.McMaster-Carr Supply Company Feb <http://www.mcmaster.com/>.P. Ponk Aviation. “Propeller Tip Speed Calculator.” Hoverhawk. 10 Feb <http://www.hoverhawk.com/propspd.html>.Vawter, Richard. “Drag Force in a Medium.” Western Washington University. Dec Feb <http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/-DragForce.html>.White, Frank M. Fluid Mechanics. Fifth Edition. New York: McGraw-Hill, 2002.