HOVERCRAFT: BODY AND FRAME A thesis submitted to the Faculty of the Mechanical Engineering Technology Program of the University of Cincinnati in partial fulfillment of the requirements for the degree of Bachelor of Science in Mechanical Engineering Technology at the College of Engineering & Applied Science by JEREMY SIDERITS Bachelor of Science University of Cincinnati May 2011 Faculty Advisor: Ahmed Elgafy, PhD TABLE OF CONTENTS HOVERCRAFT: BODY AND FRAME .................................................................................. 1 TABLE OF CONTENTS .......................................................................................................... II LIST OF FIGURES ................................................................................................................ III LIST OF TABLES .................................................................................................................. III ABSTRACT ............................................................................................................................ IV PROBLEM STATEMENT AND RESEARCH ....................................................................... 1 PROBLEM STATEMENT AND BACKGROUND ........................................................................................................1 PRODUCT RESEARCH ..........................................................................................................................................1 CUSTOMER FEEDBACK .......................................................................................................................................3 NEED IDENTIFICATION........................................................................................................................................4 PRODUCT OBJECTIVES ........................................................................................................................................6 CONCEPT DESIGN AND SELECTION ................................................................................ 8 FRAME DESIGN ...................................................................................................................................................8 SHELL DESIGN ....................................................................................................................................................9 CONCEPT DESIGN AND CALCULATIONS ..................................................................... 10 BOTTOM HULL DESIGN .................................................................................................................................... 10 FLOOR DESIGN ................................................................................................................................................. 11 RIB DESIGN ...................................................................................................................................................... 12 STRINGER DESIGN ............................................................................................................................................ 13 URETHANE CORE.............................................................................................................................................. 13 TOTAL BUOYANCY ........................................................................................................................................... 15 FABRICATION AND ASSEMBLY ...................................................................................... 15 RIBS AND STRINGERS ....................................................................................................................................... 15 FOAM ............................................................................................................................................................... 17 HULL ................................................................................................................................................................ 17 TESTING ................................................................................................................................ 18 TESTING METHODS .......................................................................................................................................... 18 TESTING RESULTS ............................................................................................................................................ 18 PROJECT MANAGEMENT .................................................................................................. 18 SCHEDULE ........................................................................................................................................................ 18 PRELIMINARY BUDGET ..................................................................................................................................... 19 ACTUAL BUDGET ............................................................................................................................................. 19 REFERENCES ....................................................................................................................... 20 APPENDIX A - RESEARCH................................................................................................... 1 APPENDIX B – SURVEY RESULTS ..................................................................................... 1 APPENDIX C – QFD ............................................................................................................... 1 APPENDIX D – SCHEDULE AND BUDGET ....................................................................... 1 APPENDIX E – MATERIALS AND PARTS LIST ................................................................ 3 ii LIST OF FIGURES Figure 1: UH-10F Entry Level .................................................................................................. 1 Figure 2: Neoteric Hovertrek .................................................................................................... 2 Figure 3: UH-XRW Hoverwing................................................................................................ 2 Figure 4 - Ribs and Stingers...................................................................................................... 8 Figure 5 - Plywood Shell .......................................................................................................... 9 Figure 6 - Full Hovercraft Assembly ...................................................................................... 10 Figure 7 - Urethane Core Capacity ......................................................................................... 14 Figure 8 - Ribs Assembled ...................................................................................................... 16 Figure 9 - Ribs and Stringers .................................................................................................. 16 Figure 10 - Styrofoam in Hull ................................................................................................. 17 LIST OF TABLES Table 1: Customer Importance Table 2: Engineering Characteristics Table 3: Customer Features Table 4: Schedule Table 5: Proposed Budget 3 4 5 18 19 iii ABSTRACT Hovercraft are relatively unknown to most of the general public. They have great potential as recreational vehicles, yet many people don’t even know of their existence. A hovercraft was constructed that could have the ability to appeal to the public as a form of recreational transportation, a la motorcycles and jet skis. By collecting customer feedback, different product objectives and design alternatives were evaluated. A design was devised that would take into account important customer features and result in a hovercraft that would appeal to a large number of people. Materials were chosen that would provide a sturdy, light structure. All joints were sealed, and all wood was primed and painted to prevent water damage. Heavy components, such as the engine and fan, were securely bolted to the frame. Through careful design and the proper selection of components, the hovercraft hull was built. iv v Hovercraft: Body and Frame Jeremy Siderits PROBLEM STATEMENT AND RESEARCH PROBLEM STATEMENT AND BACKGROUND Vehicles are generally divided into three categories based on the terrain on which they travel: land, water and air. Most vehicles are restricted to only one of these categories. There is one vehicle, however, that works in two of these categories, specifically land and water. This is a hovercraft (1). While hovercrafts do exist, their lack of an effective braking system and poor maneuverability have prevented them from widespread acceptance (2). In order to correct these problems, the engineering principles of the combustion engine for power as well as forward and reverse air propulsion for acceleration and deceleration will be applied. The principles of lift, aerodynamics, and manufacturing will also be applied in order to design and fabricate a fully functional hovercraft without the flaws mentioned above. This vehicle will provide both recreation and practicality for emergency situations on any surface. It will truly be an all-in-one vehicle that will not be limited by terrain like today’s popular vehicles. The project will require 3 persons and be broken down as follows: Body and Frame: Jeremy Siderits Propulsion and Braking: David Louderback Lift and Steering: Kelly Knapp PRODUCT RESEARCH A hovercraft is a vehicle that uses a lift fan to create an air cushion on which it glides over a surface (2). A separate thrust fan propels the vehicle forward and rudders provide the steering (1). Several manufacturers of hovercraft exist and they each offer a product with different features. Figure 1 shows a UH-10F Entry Level Hovercraft (3). This can be built from a kit designed by Universal Hovercraft. This is a good way for a first-timer to be introduced to hovercraft building, but it has many limitations. It only seats one person. A single 10 hp engine provides both the lift and the thrust, giving it a low top speed. It does not have brakes or a reverse feature. Being so small, it is more sensitive to the terrain and could be dangerous in a collision. A single engine provides the lift and the thrust Figure 1: UH-10F Entry Level 1 Hovercraft: Body and Frame Jeremy Siderits Figure 2 shows a Hovertrek, manufactured by Neoteric (4). These hovercraft are unique because they feature reverse thrust buckets that are able to close behind the thrust fan and redirect airflow towards the front on the craft, causing it to slow down or move in reverse. Neoteric hovercraft are single engine vehicles. This makes them lighter, but some of the air from the thrust fan must be diverted underneath the craft to provide lift, which slightly limits the top speed. Additionally, they use 2-cycle engines which are noisy and less reliable than 4cycle engines. Figure 2: Neoteric Hovertrek Reverse thrust buckets redirect airflow towards the front of the hovercraft Figure 3 shows the UH-19XRW Hoverwing, manufactured by Universal Hovercraft (5). Most hovercraft fly one inch or less above the ground (6), but the Hoverwing has a cruising altitude at 6 feet, and can even soar as high as 20 feet. This vehicle can provide thrills that no other hovercraft can, but it is more dangerous. Because it flies so high off the ground, it required a more enclosed cockpit. This detracts from the open-air powersport style. Enclosed cockpit Wings provide lift Figure 3: UH-XRW Hoverwing After the research was conducted the best features from each hovercraft were determined. These features, as well as others that were deemed appropriate for a recreational hovercraft, were put into a survey and given to potential customers. Their feedback was used to aid in the designing of a new, better hovercraft. 2 Hovercraft: Body and Frame Jeremy Siderits CUSTOMER FEEDBACK An interview was conducted with an employee of a powersport retailer. It was determined that the main reason people purchase such vehicles is for fun and enjoyment, as well as transportation of loads (7). An interview with two shoppers at the same retailer revealed that engine reliability is an important factor (8). After this information was gathered, a phone interview was conducted with an employee of Universal Hovercraft which revealed that 4-stroke engines are more reliable than 2-stroke for hovercraft, and bag skirts are more customer friendly than finger skirts (9). Six employees of Neoteric Hovercraft were willing to fill out a survey and provide their professional input. The survey was also handed out to seven peers who were considering buying a recreational vehicle. A total 13 responses were received. Table 1 shows a list of customer features in order of importance. Table 1: Customer Importance Customer Importance Feature Reliability Durability Maneuverability Speed Safety Effective brakes Cost Ease of use Appearance Ability to travel in reverse Low noise Cargo space Ability to tow skiers/tubers Avg 4.54 4.54 4.31 4.23 4.15 4.15 3.92 3.75 3.62 3.15 2.92 2.23 2.00 This survey makes it clear that features such as reliability and durability are very important to the customer in this type of vehicle, while cargo space and tow capability are not important. 3 Hovercraft: Body and Frame Jeremy Siderits NEED IDENTIFICATION A Quality Function Deployment chart was developed to get the relative weight percent. Engineering characteristics were listed that would support each customer feature. Each engineering characteristic was assigned a number depending on its relationship to a particular customer feature. These numbers were used to determine the absolute and relative importance for each engineering characteristic. Table 2 shows each individual engineering characteristic in order of absolute importance. Table 2: Engineering Characteristics Proper tip speed Hull constructed with fiberglass seamed marine grade plywood Reverse thrust buckets Sturdy construction 4 cycle engine powered at 85% Crash bumper Emergency stop Rearview mirrors Screen to cover the fans Aerodynamic design Warning labels/fire extinguisher Mufflers Ability to seat 3 passengers 2 ft3 cargo space Tow rope Abs. Importance 4.90 Rel. Importance 0.16 4.16 3.83 3.57 2.28 2.27 1.96 1.82 1.71 1.06 1.03 0.95 0.95 0.60 0.55 0.13 0.12 0.11 0.07 0.07 0.06 0.06 0.05 0.03 0.03 0.03 0.03 0.02 0.02 4 Hovercraft: Body and Frame Jeremy Siderits Customer importance was factored into the calculation of relative weight. This is the percent importance of each customer feature. Table 3 shows the customer features in order of relative weight. Relative weight % Durability Reliability Maneuverability Speed Safety Effective brakes Cost Ability to travel in reverse Low noise Cargo space Ability to tow skiers/tubers Relative weight Table 3: Customer Features 0.11 0.11 0.11 0.11 0.10 0.10 0.10 0.08 0.07 0.06 0.05 11% 11% 11% 11% 10% 10% 10% 8% 7% 6% 5% According to the QFD durability, reliability, maneuverability, and speed are all equally most important with 11%. The ability to tow skiers and tubers is the least important feature. If this feature was to be achieved, the frame of the hovercraft would have to be greatly reinforced, adding weight and cost. For these reasons this customer feature may be dropped from the design. 5 Hovercraft: Body and Frame Jeremy Siderits PRODUCT OBJECTIVES The following is a list of the product objectives. The customer features are broken up into engineering characteristics and objectives. They are sorted in order of importance. Reliability (11%): 1. A four cycle engine will be used, instead of the unreliable 2 cycle that is used on many hovercraft. 2. All electrical connections will be soldered and then covered with heat wrap to ensure no bare wires will be exposed to water and corrosion. 3. All fasteners will be fastened with locknuts and/or Loctite for sturdy construction. 4. Engine will be powered at 85% during normal operation in order to obtain longer engine life. Durability (11%): 1. A rubber crash bumper will be placed around the craft and attached to the exterior frame. 2. The hull will be constructed using ½” marine grade plywood coated with an epoxy primer and an enamel grade finish for waterproofing. 3. All seams will be joined by fiberglass for superior strength and waterproofing. 4. All metal used for engine mounts or frame support will be primed and painted to prevent corrosion. Speed (11%): 1. The craft will be designed to travel in excess of 40 mph on calm water. 2. Sloped shapes will be used to reduce drag. Maneuverability (11%): 1. Reverse thrust buckets can be used in addition to the normal rudders to control the movement of the craft. 2. A turning radius of zero is achievable with minimal thrust but increases with speed. Safety (10%): 1. A screen will cover the thrust and lift fans. 2. Fan tip speed will be kept below the manufacturer’s maximum tip speed in order to keep the fan blades from breaking and possibly injuring people. 3. Warning labels will be placed on: a. Any electrical device to prevent shock b. Around the fans to prevent injury c. Near engines to prevent burns 4. A fire extinguisher will be placed on board in the event that the engine catches fire. 5. All other safety requirements will be upheld based on part manuals. 6 Hovercraft: Body and Frame Jeremy Siderits Effective braking system (10%): 1. The hovercraft will feature reverse thrust buckets that cause the hovercraft to reduce speed. 2. Fifty percent of the thrust airflow will be redirected for braking allowing a deceleration equal to one half of the acceleration rate. 3. An emergency stop feature will be used to cut power to the lift fan. Pads on the bottom of the hull will prevent damage when this feature is used. Cost (10%): 1. The hovercraft will be priced similar to an ATV or Jet Ski, around $10,000 new. Ability to travel in reverse (8%): 1. The hovercraft will be equipped with reverse thrust buckets to allow the craft to travel in reverse by pulling a lever. Low noise (7%): 1. Normal operation will be at less than 85 decibels. 2. The engines will be equipped with mufflers. 3. The fan tip speed will be below the manufacturer’s maximum tip speed. This will minimize excessive sound. Cargo space (6%): 1. The design will allow at least 2 ft3 of cargo space, located under the seat or in the front of the hull. Ability to tow skiers/tubers (5%): 1. A tow rope will be able to be attached to the back of the craft. 2. In order to legally tow a skier, the craft will be able to seat 3 passengers (10). It will have rearview mirrors so the operator can verify the safety of the skier. 7 Hovercraft: Body and Frame Jeremy Siderits CONCEPT DESIGN AND SELECTION FRAME DESIGN The frame will utilize a set of ribs and stringers, as seen in Figure 4. Seven ribs will be constructed out of 2x2s and spaced 20.25 inches apart, center to center. Three stringers will be placed 17.25 inches apart, center to center. This design allows for necessary strength to support the plywood floor. The cavities in the frame will be filled with a urethane foam core, which will provide buoyancy and additional strength. Figure 4 - Ribs and Stingers 8 Hovercraft: Body and Frame Jeremy Siderits SHELL DESIGN The shell will be constructed using marine grade plywood. It will be placed over the frame and coated with a primer and enamel grade finish. The seams will be sealed with fiberglass. The strength axis of the plywood will be placed perpendicular to the main supports (the ribs), and the majority of stress will be applied perpendicular to the strength axis. This will maximize the plywood’s strength potential. ¼” thick plywood will be used for the bottom of the hull, which will have to withstand the air pressure. ½” thick plywood will be used for the floor, which will have to withstand the weight of passengers and cargo. The shell is shown in figure 5. Figure 5 - Plywood Shell 9 Hovercraft: Body and Frame Jeremy Siderits CONCEPT DESIGN AND CALCULATIONS The final 3D model for the hovercraft assembly can be seen in Figure 6 below. Figure 6 - Full Hovercraft Assembly BOTTOM HULL DESIGN The first step in designing the hull was to determine the forces and pressure that would be acting on it. The air pressure underneath the hull was known to be 15.7 psf. The bottom panel of plywood would have to withstand this pressure. The position of the strength axis, direction of applied stress, and support distance were used to select the proper stress equations. The factors in the equations were found in various tables (11). 10 Hovercraft: Body and Frame Jeremy Siderits Equation 1 – Bending Stress 120 Fb S 120 105 wb 30.0 psf 2 20.5 2 L1 Equation 2 – Shear Stress 20 Fs (lb / Q) 20 135 ws 142 psf L2 19 Equation 3 – Deflection Due to Bending Stress 4 L3 20.75 4 b .00709 1743EI 1743 15000 Equation 4 – Deflection Due to Shear Stress 2 Ct 2 L2 120 .5 2 19 2 s .00057 1270 EI 1270 15000 Equation 5 – Stress Due to Deflection L / 160 20.5 / 160 wd 16.7 psf total .00709 .00057 From the above equations, 16.7 psf is the lowest stress the ¼” plywood can withstand, so it is the limiting factor. 16.7 psf > 15.7 psf. Because the limiting factor is greater than the air pressure under the hull, the ¼” plywood will withstand the pressure. FLOOR DESIGN The next step was to design for the stress on the floor. The floor should be able to hold 900 lbs of weight, including passengers, engine, and cargo. This becomes 26.1 psf over the area of the floor. ½” marine grade plywood will be used, so the equations were adjusted accordingly. Equation 6 – Bending Stress 120 Fb S 120 430 wb 123 psf 2 20.5 2 L1 Equation 7 – Shear Stress 20 Fs (lb / Q) 20 305 ws 321 psf L2 19 Equation 8 – Bending Stiffness 4 L3 20.75 4 b .000759 1743EI 1743 140000 11 Hovercraft: Body and Frame Jeremy Siderits Equation 9 – Shear Stiffness 2 Ct 2 L2 120 .5 2 19 2 s .000006 1270 EI 1270 140000 Equation 10 – Stress Due to Deflection L / 240 20.5 / 240 wd 111.7 psf total .000759 .000006 The lowest stress the ½” thick plywood can withstand is the bending stress of 123 psf. This is greater than the estimated stress of 26.1 psf, so ½” marine grade plywood is safe to use. RIB DESIGN The next step was to verify that 2x2s could provide the necessary support for the plywood hull. Calculations were used to determine the safety of the ribs (12). Equation 11 – Weight per rib 900lb 1.5in 78in W .109 psi 115.8lb / rib 7ribs rib The weight per rib was used to find the maximum shear stress and maximum moment. Equation 12 – Max Shear Stress Vmax 115.8 / 2 57.9lb Equation 13 – Max Moment M max .5 57.9lb 39in 1129lb * in After finding the section modulus, the maximum stress could be determined. Equation 14 – Section Modulus b 3 1.53 S 1.125in 3 3 3 Equation 15 – Max Stress M 1129 max 1000 psi S 1.125 Pine will be used in the 2x2s. This has an ultimate strength su = 5800 psi. This gives a safety factor N = 5.8. 12 Hovercraft: Body and Frame Jeremy Siderits STRINGER DESIGN The next step was to determine the safety of the stringers. First, the weight per stringer was determined. Then, the maximum shear stress and maximum moment were determined. Equation 16 – Weight per stringer 1.5in 106in 900lbs 283lb / stringer W .109 psi 3stringers stringer Equation 17 – Max Shear Stress Vmax 283 / 2 141.5lbs Equation 18 – Max Moment M max .5 141.5lb 53in 3750lb * in The section modulus is the same as the ribs. Taking the section modulus and maximum moment, it was possible to solve for the maximum stress. Equation 19 – Max Stress M 3750 max 3333 psi S 1.125 Factoring in pine’s ultimate strength of su = 5800 psi, this gives a safety factor of N = 1.74. This is not a cause for strong concern, however, because the additional rigidity provided by the ribs, plywood, and urethane core will raise the amount of stress the stringers will be able to withstand. URETHANE CORE An expanding urethane foam will be poured into the cavities between the ribs and stringers, providing extra strength as well as buoyancy. Figure 7 shows the square cavities in which the urethane will be placed, and then sandwiched inside the plywood hull assembly. 13 Hovercraft: Body and Frame Jeremy Siderits Figure 7 - Urethane Core Capacity Knowing the dimensions of the cavities, as well as the dimension of the space in the air duct that will be reserved for foam, it was possible to calculate the volume of urethane foam that can be used. Equation 20 – Volume of Hull Cavities 1 ft 3 19.0in 16.0in 1.5in 8 2.11 ft 3 3 1728in Equation 21 – Volume of Duct Cavities 1 ft 3 .5 3in 7in 402in 11.5in 3in 402in 10.469 ft 3 3 1728in Equation 22 – Total Potential Foam Capacity 2.11 10.469 12.57 ft 3 Knowing that the selected urethane foam provides 60.5 lbs/ft3 of additional buoyancy (13), it is possible to calculate the buoyancy provided by the foam. Equation 23 – Total Foam Buoyancy lb 60.5 3 12.57 ft 3 760.5lbs ft 14 Hovercraft: Body and Frame Jeremy Siderits TOTAL BUOYANCY The hovercraft needs to have the ability to float on water without sinking. It is important to verify that the expected weight can be held by the buoyancy. Knowing that 5 sheets of ¼” plywood and 1 sheet of ½” plywood will be used, as well as the buoyancy of marine grade plywood (35 lbs/ft3) and the weight of water (62.5 lbs/ft3), it is possible to calculate the buoyancy provided by the plywood hull. Equation 24 – Volume of Plywood 1 ft 1 ft (4 ft 8 ft .25in 5) (4 ft 8 ft .5 ft ) 4.67 ft 3 12in 12in Equation 25 – Total Buoyancy of Plywood lb lb 4.67 ft 3 62.5 3 35 3 128.4lbs ft ft Adding the buoyancy of plywood to the buoyancy of foam, the total buoyancy can be obtained. Equation 26 – Total Buoyancy 128.4lbs 760.5lbs 888.9lbs Equation 26 describes the extra buoyancy provided by the plywood and urethane, in addition to the buoyancy needed to float an unloaded hull. In other words, it is the amount of cargo the hovercraft can hold over water without sinking. FABRICATION AND ASSEMBLY RIBS AND STRINGERS The ribs and stringers were cut from 2x2 Douglas fir. They were cut to the varying lengths determined from the SolidWorks sketches. When it was necessary to make an angled cut, an adjustable miter saw was used to achieve this. 15 Hovercraft: Body and Frame Jeremy Siderits Figure 8 - Ribs Assembled They were assembled using impact drills to drive in the screws. Loctite PL Premium Polyurethane Construction Adhesive was applied to each wood joint before it was screwed together, ensuring a very strong bond. When all the ribs were assembled, they were attached to the stringers, forming the basic skeletal structure for the hovercraft hull. Figure 9 - Ribs and Stringers 16 Hovercraft: Body and Frame Jeremy Siderits FOAM In order to increase buoyancy, 2 lb density urethane foam was purchased from US Composites and poured into the ductwork within the hull. Styrofoam was placed in the empty spaces between the ribs and stringers. Figure 10 - Styrofoam in Hull HULL The outside skin for the hull was cut from ¼” marine grade plywood. A table saw was used to cut compound angles, in order for the plywood to fit perfectly over the skeleton. ½” thick marine grade plywood was used to provide extra strength for the floor of the hull. The same construction adhesive was applied to the plywood before it was screwed onto the frame, providing a bond that would not leak water and damage the structure of the craft. 17 Hovercraft: Body and Frame Jeremy Siderits TESTING TESTING METHODS As construction was carried out, the hovercraft was suspended over sawhorses. Large components were attached to the hull, and team members were often inside the passenger compartment. This is how it was determined that the hull could withstand the weight of all passengers and cargo. When the hovercraft is operable, a buoyancy test will be undertaken. One passenger will take the craft to shallow water and turn off the engine. Weight will be added to the passenger area until either the design weight is reached, or the craft sinks to an uncomfortable level. TESTING RESULTS The weight test was conducted successfully. The craft, fully loaded, would not bend under its weight. The combination of ribs, stringers, urethane foam core, and plywood skin proved to be rigid enough to withstand the design weight. PROJECT MANAGEMENT SCHEDULE The first milestone on the schedule was the Proof of Design Contract, which occurred on 11/24/10. The last date is the due date of the final report, 5/30/11. Table 4 contains some key dates of the schedule; the full schedule can be found in Appendix D. Table 4: Schedule Proof of Design Contract Design Freeze Oral Design Presentation Design Report Tech Expo Oral Final Presentation Final Report Due 11/24/2010 1/31/2011 2/28/2011 3/7/2011 5/20/2011 5/23/2011 5/30/2011 18 Hovercraft: Body and Frame Jeremy Siderits PRELIMINARY BUDGET A preliminary budget was developed in order to provide and estimation of the costs of this project. Table 4 contains the budget, with individual components condensed into the total cost of each system. Table 5: Proposed Budget System Cost Lift $ 525.00 Thrust $ 600.00 Body $ 520.00 Steering $ 150.00 Electrical $ 200.00 Misc. $ 375.00 Total $ 2,370.00 It was decided to switch from a 2-engine to a single engine craft. This will reduce the total cost, as only one engine will need to be purchased. The drivetrain components were approximated to cost $600. The original estimated price of the hull is believed to be an underestimate. The new estimated total is $3750. ACTUAL BUDGET Sponsorship donations accounted for $5000. The team members split the remaining cost of the craft, which was also $5000. The estimated cost for the team members was $3750; this was an underestimate of $1250. 19 Hovercraft: Body and Frame Jeremy Siderits REFERENCES 1. Perozzo, James. Hovercrafting as a Hobby. Bend, OR : Maverick Publications, 2001. 2. Northern Hovercraft. FAQ'S. Nothern Hovercraft. [Online] Nothern Hovercraft. [Cited: 11 20, 2010.] http://www.northernhovercraft.com/faq.html. 3. Universal Hovercraft. UH-10F Entry Level Hovercraft. Universal Hovercraft. [Online] Universal Hovercraft. [Cited: 09 29, 2010.] http://www.hovercraft.com/content/index.php?main_page=index&cPath=33_40. 4. Neoteric Hovercraft. 4 Passenger Recreational Specifications. Neoteric Hovercraft. [Online] Neoteric Hovercraft. [Cited: 09 20, 2010.] http://neoterichovercraft.com/specifications/4Lspecifications.htm. 5. Universal Hovercraft. 19XRW Hoverwing. Universal Hovercraft. [Online] Universal Hovercraft. [Cited: 09 29, 2010.] http://www.hovercraft.com/content/index.php?main_page=index&cPath=2. 6. Fitzgerald, Christopher and Wilson, Robert. Light Hovercraft Design. Foley, AL : The Hoverclub of America, Inc., 1995. 7. Baker, Larry and Kathleen. Power Sports Enthusiasts. Cincinnati, OH, 10 01, 2010. 8. Simons, Chuck. Power Sports Sales Specialist. Cincinnati, OH, 10 01, 2010. 9. Springer, Ryan. Hovercraft Manufacturer. Rockford, IL, 09 29, 2010. 10. Ohio Department of Natural Resources, Division of Watercraft. The legal requirements of boating: towing a person with a boat or PWC legally. BOAT-ED. [Online] Ohio Department of Natural Resources, Division of Watercraft, 04 02, 2010. [Cited: 09 29, 2010.] www.boat-ed.com/oh/course/p4-15_reqspectotowing.htm. 11. APA - The Engineered Wood Association. Panel Design Specification. [Online] 2008. [Cited: January 20, 2011.] http://www.apawood.org/pdfs/managed/D510.pdf?CFID=25720809&CFTOKEN=47538112. 12. Mott, Robert L. Machine Elements in Mechanical Design. Upper Saddle River : Pearson Prentice Hall, 2004. 13. US Composites. 2 Part Liquid Expanding Urethane Foam. [Online] 2008. [Cited: February 3, 2011.] http://www.shopmaninc.com/foam.html. 20 APPENDIX A - RESEARCH Problem: Owners of recreational vehicles such as ATVs, boats, and jet-skis are limited to travel depending on whether they are on land or water. The hovercraft is a recreational vehicle that can travel on any type of surface including land or water. While several companies manufacture hovercraft, they are very expensive and usually include minimal features. A hovercraft will be developed that would entice the power-sports enthusiast by offering the features of all the other recreational vehicles. This hovercraft will be a total replacement. Also the hovercraft to be developed will be built for less than $10,000 in order to compete against present-day recreational vehicles. Closest MET Projects: OCAS 1:4 Jet Propulsion Boat Joseph Duffey, Douglas Weber, Adam Patterson, 1987 One-Man Propeller Driven Airboat Sean Nguyen, 1990 These two projects are similar to a hovercraft in that they both use the propulsion of air to move the craft, rather than using a propeller in the water. However, these two projects differ from ours because they are still boats, and being so, they are limited to use only on water. Our hover craft will float on a cushion of air and as a result, will be able to easily travel on nearly any terrain, whether it is land or water. Appendix A1 Interview Notes: Interview with power sports sales specialist, Oct. 1, 2010 Chuck Simons (513-752-0088) Beechmont Motorsports, 646 Mount Moriah Drive, Cincinnati, OH, 45245. Sells recreational vehicles including ATVs, Jet-Skis, and Dirtbikes. All vehicles offer excitement but are limited by either land or water. Chuck stated that the reasons why people buy recreational vehicles are: Fun and enjoyment Hunting Farm Help Convenience (carrying big loads) Features or specifics that most customers are interested in include: Automatic Transmission Fuel-Injected Engine Speed Noise Levels Cargo area Carrying racks (For ATVs) Interview with power sports enthusiasts, Oct. 1, 2010 Larry and Kathleen Baker (did not want to give contact number) Beechmont Motorsports, 646 Mount Moriah Drive, Cincinnati, OH, 45245. Owners of an ATV and a Jetski. Larry and Kathleen said that the newer engines are very electrical and their brand new ATV and jet-ski models had broken down several times and were difficult to repair. They stated they would never buy a newer model again and that older style engines were more reliable and much simpler. They stated that their jet-ski was fun because they could tow their children on a tube. (In our research, we found that in the state of Ohio, a motorsports vehicle is only capable to pull a third party if it is rated to carry at least three people on-board and it has mirrors to see behind the vehicle). Interview with hovercraft manufacturer, Sept. 29, 2010 Ryan Springer (815-963-1200) Universal Hovercraft, 1218 Buchanan Street, Cincinnati, OH, 45245. Ryan stated that: The hovercraft’s hull should be slightly tapered and buoyant so that it floats in water in case of engine failure. Universal Hovercraft is proud that they only use four-stroke engines. A twostroke engine produces loud winding noise levels and they are less reliable. A bag skirt is more customer-friendly since they are thicker than finger skirts and repairing is easy to do in the field with scrap PVC coated nylon and skirt glue. Also, the bottoms of the finger skirt deteriorate quickly since they are typically made of thinner material. Appendix A2 Related Products: http://www.hovercraft.com/co ntent/index.php?main_page=in dex&cPath=33_40 9/29/10 UH-10F Hovercraft The UH-10F Entry Level Hovercraft is a great design for first time builders, high school technology classes and home science projects. First time builders and students get hands-on experience in woodworking, fiberglass, small engines, propellers, as well as gaining knowledge in engineering, aerodynamics and physics. Offered in a kit priced at $1,499 Very reasonable price Price does not include wood, hardware, upholstery, wire, or paint costs Only accommodates one person Only one engine - limits power and speed Low HP 25 – 35 MPH Travels on all surfaces Very limited design A single 10 hp Tecumseh horizontal shaft engine turns a two blade 36inch ducted propeller that provides both lift and thrust. This single engine design is both simple and reliable, and has been successfully built and flown by students in hundreds of schools and colleges throughout the world. The 10F complies with the Hoverclub of America Entry Level racing requirements. It's built from a foam and plywood sandwich construction. The combination of these materials makes a low cost, high strength composite structure that is un-sinkable. Driving the craft is easy as it has only two controls; steering and throttle. Slowly advancing the throttle will bring the craft up on cushion. Adding a little more power accelerates the craft. Speed is easily controlled by increasing or decreasing engine rpm. First time pilots can learn to operate the craft in a very short period of time. The craft will operate on land, water, snow, ice, mud, parking lots, football fields, ponds and rivers. Speed varies over each terrain. Smoother terrain will allow the craft to achieve higher speeds while rough terrain will slow the craft. The Hoverclub of America has designed a racing program specifically for the 10F & 10F2 Entry Level Hovercraft. The program is designed to allow close competition between individual competitors, High Schools and Universities at a very affordable price. See Hoverclub of America for more information. Appendix A3 Reverse buckets offer braking and reverse capabilities Limited to max 2 foot waves 16.7% slope gradient max Expensive – 20-30K depending on options http://neoterichovercraft.com/specifications/4L specifications.htm 9/20/10 Hovertrek, Neoterichovercraft.com, Neoteric Hovercraft Neoteric is the original light hovercraft manufacturer and the Hovertrek™ is the culmination of Neoteric’s 40 years of experience in light hovercraft design, development and engineering. Its aesthetically appealing design embodies all the advantages and advances Neoteric has innovated: side-by-side seating, fully enclosed cabin, highly developed reverse thrust for braking and maneuverability, more cockpit room, increased thrust and low weight. Engineered to satisfy expectations and to give long life and value for money, the Hovertrek™ is recognized as the industry standard for recreational personal hovercraft. 4 person, 750 lb payload 60 mile range 45 mph max forward speed on calm water 25 mph max reverse speed on calm water 83 dB (A) Appendix A4 Ability to “fly” at very low heights Extremely expensive - $85K Must have a skilled operator Increased level of danger Very high speeds necessary to fly Large, open terrain needed to fly http://www.hovercraft.com/content/index.ph p?main_page=index&cPath=2 , 9/29/10, 19XRW Hoverwing, hovercraft.com, Universal Hovercraft Universal Hovercraft is proud to offer the UH19XRW Hoverwing™ ground-effect vehicle for recreational, industrial, commercial, military sales. It is available to our customers on a ready to run turnkey basis. The Hoverwing™, designed as a high performance hovercraft, is unique because of the ability to add wings for flight in ground-effect. Flying in ground-effect enables you to clear obstacles and fly over rough water at speeds in excess of 75 mph. Cruise altitude is 2 to 6 feet and the craft can jump up to 20 feet to clear large obstacles. Operating in ground-effect does not require a pilot's license, and the craft is registered as a boat which brings a wide range of new opportunities to the commercial and tourism industry. Removing the wings from the Hoverwing™ takes just 10 minutes. With the wings removed the Hoverwing™ converts into Sport mode, a sleek high performance hovercraft, able to carry 4 to 6 passengers into areas that can't be reached with any other vehicle. The Hoverwing™ can be configured in many different ways to accommodate your passengers or equipment needs. Appendix A5 APPENDIX B – SURVEY RESULTS HOVERCRAFT CUSTOMER SURVEY Please fill out this survey so we can get a better understanding of what the public wants in a hovercraft. How important is each feature to you for the design of a recreational hovercraft? Please circle the appropriate answer. Safety Durability Reliability Maneuverability Effective brakes Ability to travel in reverse Low noise Cargo space Speed Ability to tow skiers/tubers Cost 1 = low importance 5 = high importance 1 1 1 1 1 2 2 2 2 2(1) 3(5) 3(1) 3(1) 3(1) 3(3) 4(1) 4(4) 4(4) 4(7) 4(2) 5(7) 5(8) 5(8) 5(5) 5(7) N/A N/A N/A N/A N/A 1 2(3) 3(6) 4(3) 5(1) N/A 1(1) 1(4) 1(1) 2(5) 2(4) 2(1) 3(3) 3(4) 3 4(2) 4 4(3) 5(2) 5(1) 5(8) N/A N/A N/A 1(6) 2(2) 3 4(4) 5 N/A 1(1) 2(1) 3(2) 4(3) 5(6) N/A AVG 4.15 4.54 4.54 4.31 4.15 3.15 2.92 2.23 4.23 2.00 3.92 How much would you be willing to pay for this vehicle? $1000-$2000 $2000-$5000(1) $5000-$10,000(3) $10,000-$15,000(6) $15,000+(3) AVG Cost Range – High end of $5000 - $10000 Thank you for your time. Appendix B1 APPENDIX C – QFD Appendix C1 Hovercraft Product Objectives The following is a list of product objectives and how they will be obtained or measured to ensure that the goals of the project were met. The product objectives will focus on the various aspects of a hovercraft. The hovercraft is a recreational vehicle and will be designed to provide safe enjoyment for its users. Reliability (11%): 5. A four cycle engine will be used, instead of the unreliable 2 cycle that is used on many hovercraft. 6. All electrical connections will be soldered and then covered with heat wrap to ensure no bare wires will be exposed to water and corrosion. 7. All fasteners will be fastened with locknuts and/or Loctite for sturdy construction. 8. Engine will be powered at 85% during normal operation in order to obtain longer engine life. Durability (11%): 5. A rubber crash bumper will be placed around the craft and attached to the exterior frame. 6. The hull will be constructed using ½” marine grade plywood coated with an epoxy primer and an enamel grade finish for waterproofing. 7. All seams will be joined by fiberglass for superior strength and waterproofing. 8. All metal used for engine mounts or frame support will be primed and painted to prevent corrosion. Speed (11%): 3. The craft will be designed to travel in excess of 40 mph on calm water. 4. Sloped shapes will be used to reduce drag. Maneuverability (11%): 3. Reverse thrust buckets can be used in addition to the normal rudders to control the movement of the craft. 4. A turning radius of zero is achievable with minimal thrust but increases with speed. Appendix C2 Safety (10%): 6. A screen will cover the thrust and lift fans. 7. Fan tip speed will be kept below the manufacturer’s maximum tip speed in order to keep the fan blades from breaking and possibly injuring people. 8. Warning labels will be placed on: a. Any electrical device to prevent shock b. Around the fans to prevent injury c. Near engines to prevent burns 9. A fire extinguisher will be placed on board in the event that the engine catches fire. 10. All other safety requirements will be upheld based on part manuals. Effective braking system (10%): 4. The hovercraft will feature reverse thrust buckets that cause the hovercraft to reduce speed. 5. Fifty percent of the thrust airflow will be redirected for braking allowing a deceleration equal to one half of the acceleration rate. 6. An emergency stop feature will be used to cut power to the lift fan. Pads on the bottom of the hull will prevent damage when this feature is used. Cost (10%): 2. The hovercraft will be priced similar to an ATV or Jet Ski, around $10,000 new. Ability to travel in reverse (8%): 2. The hovercraft will be equipped with reverse thrust buckets to allow the craft to travel in reverse by pulling a lever. Low noise (7%): 4. Normal operation will be at less than 85 decibels. 5. The engines will be equipped with mufflers. 6. The fan tip speed will be below the manufacturer’s maximum tip speed. This will minimize excessive sound. Appendix C3 Cargo space (6%): 2. The design will allow at least 2 ft3 of cargo space, located under the seat or in the front of the hull. Ability to tow skiers/tubers (5%): 3. A tow rope will be able to be attached to the back of the craft. 4. In order to legally tow a skier, the craft will be able to seat 3 passengers. 5. It will have rearview mirrors so the operator can verify the safety of the skier. Appendix C4 APPENDIX D – SCHEDULE AND BUDGET Schedule: 5/29 - 6/4 5/22 - 5/28 5/15 - 5/21 5/8 - 5/14 5/1 - 5/7 4/24 - 4/30 4/17 - 4/23 4/10 - 4/16 4/3 - 4/9 3/27 - 4/2 3/20 - 3/26 3/13 - 3/19 3/6 - 3/12 2/27 - 3/5 2/20 - 2/26 2/13 - 2/19 2/6 - 2/12 1/30 - 2/5 1/23 - 1/29 1/16 - 1/22 1/9 - 1/15 1/2 - 1/8 12/26 - 1/1 12/19 - 12/25 Tasks in black text are equally shared by the group members 12/12 - 12/18 12/5 - 12/11 11/28 -12/4 11/21 - 11/27 DATE Jeremy Siderits, Kelly Knapp, Dave Louderback TASK Proof of design contract 24 Hovercraft concept development 6 Preliminary hovercraft design 31 19 Engine 13 15 Fans 20 29 Gearing (sizes, ratios, and type) 27 12 Lift system 3 19 Thrust system 10 19 Steering 17 19 Throttle and controls 24 19 Hull 31 19 Winter Break (CAD drawings only) Long delivery components Major Component Design freeze 2 2 31 31 31 31 Final hovercraft design 21 Hovercraft BOM 21 3 18 Order hovercraft components 28 Oral design presentation 28 3 18 Design report Component fabrication 7 18 14 Assembly 9 Demo to advisor 9 Demo to faculty Oral final presentation Final report due 16 23 30 Appendix D1 Hovercraft Budget: Hovercraft Budget System Lift Component Bag Skirt Lift Engine Lift Fan Muffler Description Vinyl coated nylon fabric 4-stroke engine Multi-blade fan Muffler system Price $125.00 $100.00 $250.00 $50.00 Thrust Thrust Engine Thrust Fan Belt System Reverse Buckets Muffler 4-stroke engine (Discounted) Mult-blade fan Belt and pulleys Fabricated fiberglass shell Muffler system $100.00 $350.00 $50.00 $50.00 $50.00 Body 1/2" thick marine grade plywood Material used for the bottom of the hull $150.00 misc wood Material used for ribs and top of the hull $100.00 Fiberglass and resin Joint support and waterproofing material $125.00 In-line Seating Fabric and support for seating $40.00 Paint Enamel based paint for superior protection $75.00 Warning Labels Keep hand away, hot, electrical hazard $10.00 Duct Screen Wire sceen for fan protection $20.00 Steel Tube Tube stock for engine support Donated Steering Handlebars Rudders Handlebar system Rudder system $100.00 $50.00 Electrical Temperature Gauge Temperature Gauge Tachometer Tachometer Battery Alternator Temperature guage for lift engine Temperature guage for thrust engine RPM guage for lift engine RPM guage for thrust engine 12v Battery System to charge battery $25.00 $25.00 $25.00 $25.00 $50.00 $50.00 Misc Misc parts and hardware N/A $375.00 Total $2,370.00 Appendix D2 APPENDIX E – MATERIALS AND PARTS LIST 5 sheets 4’x8’x1/4” marine grade plywood 1 sheet 4’x8’x1/2” marine grade plywood 2x2s, 125 linear feet, pine wood 2 lb density urethane foam, Part # FOAM-0216 from US Composites Polyurethane rubber strip, Part # 8997K551 from McMaster-Carr 6-Gallon Attwood gas tank 2 gallons fiberglass resin 100 linear feet fiberglass mesh tape 1 gallon epoxy primer 1 gallon marine enamel paint Wood screws Appendix D3