Hovercraft thrust system and drivetrain

HOVERCRAFT THRUST SYSTEM AND DRIVETRAIN

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

DAVID LOUDERBACK

Bachelor of Science University of Cincinnati

May 2011

Faculty Advisor: Dr. Ahmed Elgafy

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ABSTRACT The thrust system and drivetrain for the hovercraft had to be designed and constructed to enable adequate acceleration and a top speed of 50-60 mph. In the end, the thrust to weight ratio puts this craft’s acceleration in the “racing craft” category and the top speed has been calculated to be 68.5 mph. The drivetrain had to be designed to efficiently and reliably transfer the power from the 105 hp automotive engine to the 42” fan. A synchronous belt was chosen to reduce the likelihood of belt slippage and to efficiently transfer the power. Since a single engine/fan integrated hovercraft setup was chosen, the engine and drivetrain for the thrust system also had to power the lift system. Due to this, some compromises had to be made, such as a variable blade fan, which can accept 6, 9, or 12 fan blades. Six blades would be better strictly for thrust, while 12 blades would better suit a lift system. The available adjustment gives room for compromise.

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ACKNOWLEDGEMENTS I would like to thank Professor Elgafy for his support and encouragement throughout this project. Also great thanks goes out to John Calder of Dorsey Alexander, Inc. and Scott Hartman of Onvio for their generous donations to the Hovercraft. John and Scott provided all of the power transmission components for this project. Without the donation of materials and use of the shop at Blue Ash Tool and Die, this project would not have been possible. I would also like to thank Jeremy Brewer for his donation of the Mazda engine and his assistance in getting it running, as well as all of our additional sponsors.

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TABLE OF CONTENTS

HOVERCRAFT THRUST SYSTEM AND DRIVETRAIN .................................................... 1

ABSTRACT ............................................................................................................................. II

ACKNOWLEDGEMENTS .................................................................................................... III

TABLE OF CONTENTS ........................................................................................................ IV

LIST OF FIGURES .................................................................................................................. V

LIST OF TABLES .................................................................................................................. VI

INTRODUCTION ..................................................................................................................... 1

PRODUCT RESEARCH .......................................................................................................................................... 2

CUSTOMER FEEDBACK AND SURVEY ANALYSIS ....................................................... 5

INTERPRETATION OF SURVEY RESULTS ............................................................................................................. 6 PRODUCT OBJECTIVES ........................................................................................................................................ 7

DESIGN .................................................................................................................................... 9

DESIGN ALTERNATIVES AND SELECTION ........................................................................................................... 9 SELECTION OF AN ENGINE: .............................................................................................................................. 10 FAN SELECTION: .............................................................................................................................................. 13 TOP SPEED CALCULATIONS: ............................................................................................................................ 16 POWER TRANSMISSION: ................................................................................................................................... 18 THRUST DUCT AND STATOR BLADES: .............................................................................................................. 25

SCHEDULE AND BUDGET ................................................................................................. 26

FABRICATION ...................................................................................................................... 27

TESTING ................................................................................................................................ 38

CONCLUSION ....................................................................................................................... 39

REFERENCES ........................................................................................................................ 40

APPENDIX A – RESEARCH DOCUMENTATION .............................................................. 1

APPENDIX B – SURVEY RESULTS ..................................................................................... 1

APPENDIX C – QFD AND PRODUCT OBJECTIVES ......................................................... 1

APPENDIX D – SCHEDULE AND BUDGET ....................................................................... 1

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LIST OF FIGURES Figure 1 - Single-engine craft.................................................................................................... 2 Figure 2 - Dual-engine craft ...................................................................................................... 2 Figure 3 - Economical "kit" hovercraft ..................................................................................... 3 Figure 4 – Reverse buckets stored to side ................................................................................. 3 Figure 5 – Reverse buckets activated ........................................................................................ 4 Figure 6 – Universal Hovercraft – Hoverwing.......................................................................... 4 Figure 7 – Thrust System Design .............................................................................................. 9 Figure 8 – Calculated Hump Drag .......................................................................................... 11 Figure 9 – Engine Donor – 1995 Mazda MX-3 ...................................................................... 12 Figure 10 – Fan Tip Speed ...................................................................................................... 14 Figure 11 – Blade Pitch vs. HP Absorbed ............................................................................... 15 Figure 12 – Dynamic Thrust vs. Speed ................................................................................... 16 Figure 13 – Total Drag vs. Speed ............................................................................................ 17 Figure 14 – Total Drag vs. Dynamic Thrust = Top Speed ...................................................... 17 Figure 15 – Power Transmission Components ....................................................................... 18 Figure 16 – Belt Profile ........................................................................................................... 19 Figure 17 – Layout of sprockets and belt ................................................................................ 20 Figure 18 – Drive Shaft Layout............................................................................................... 21 Figure 19 – Side Profile of Fan Shaft ...................................................................................... 21 Figure 20 – Shear Force and Bending Moment Diagram for Fan Shaft ................................. 22 Figure 21 – Pillow Block Bearing ........................................................................................... 23 Figure 22 – Jaw coupling shell ................................................................................................ 24 Figure 23 – Jaw coupling spider ............................................................................................. 24 Figure 24 – Thrust Duct and Stator Blades ............................................................................. 25 Figure 25 – Hovercraft Basic Frame ....................................................................................... 27 Figure 26 – Hovercraft Frame ................................................................................................. 28 Figure 27 – Hovercraft being relocated................................................................................... 28 Figure 28 – Thrust Duct Mold ................................................................................................ 29 Figure 29 – Thrust Duct with Inner Flashing Removed.......................................................... 30 Figure 30 – Completed Thrust Duct ........................................................................................ 30 Figure 31 – Engine Frame Pieces ............................................................................................ 31 Figure 32 – Engine Mounted on Frame .................................................................................. 32 Figure 33 – Fan Frame being Welded ..................................................................................... 33 Figure 34 – Completed Fan Frame Mounted with Engine ...................................................... 34 Figure 35 – Trailer Base .......................................................................................................... 35 Figure 36 – Trailer Modifications ........................................................................................... 35 Figure 37 – Completed Trailer with Hovercraft being relocated again .................................. 36 Figure 38 – 42” Fan Mounted to Hub ..................................................................................... 36 Figure 39 – Fan being test fit on Hovercraft ........................................................................... 37

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LIST OF TABLES Table 1 – Customer Importance 5 Table 2 – QFD Importance 6 Table 3 – Fan Shaft Spreadsheet Calculations 23 Table 4 – Milestone Dates 26 Table 5 – Condensed Budget 26

Hovercraft Thrust System and Drivetrain David Louderback

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INTRODUCTION There are many options for personal recreation vehicles, from snowmobiles to dirt bikes and 4-wheel ATVs to jet skis and personal boats. These vehicles are all great at what they were designed to do. The problem with each, however, is that they are quite limited in the terrain that each can travel on. Dirt bikes and ATVs are limited to travel on land, while jet skis and boats are limited to travel on water. The greatest advantage of a hovercraft is its ability to travel over all types of terrain, from paved asphalt to grassy fields to the open water. Hovercraft operate by creating a cushion of air below the craft. This cushion of air supports the weight of the craft and enables a fan or propeller to easily propel the craft in the desired direction. In addition to recreational uses, hovercraft can also be used for emergency use. In fact, a hovercraft is the only vehicle available which can safely maneuver across thin ice on a frozen lake or pond, enabling rescue teams to safely reach a victim who has fallen through the ice. While hovercraft do exist, their poor maneuverability and lack of an effective braking system have prevented them from gaining widespread acceptance. High cost and a lack of knowledge and understanding by the general public have also kept them out of the spotlight. To satisfy the requirements of this Senior Design Project, a 3-person capacity, fully functional hovercraft will be designed and built. Besides the obvious challenge of creating an operational hovercraft, the main goals of this project are to improve upon some of the hovercraft limitations mentioned in the above paragraph. The project will be divided into three parts. Jeremy Siderits will be responsible for the body and frame of the craft. Kelly Knapp will be responsible for the lift and steering systems. Lastly, David Louderback will be in charge of designing the propulsion system. While these three parts of the project are separate, they are also highly dependent upon and integrated within one another. No one team member can do much work without first consulting with the other team members, to ensure that the overall design still functions as a whole.


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PRODUCT RESEARCH

Compared to other recreational vehicles, there is relatively little information available on hovercraft, due to their rarity. In addition, few manufacturers exist. Two of the largest manufacturers in the United States are Neoteric Hovercraft, and Universal Hovercraft. Neoteric Hovercraft is focused more towards selling fully built hovercraft, while Universal Hovercraft mostly sells kits, to be assembled by the customer. There are two main classifications of hovercraft: single-engine and dual-engine. With a single-engine craft (Figure 1), a single engine and fan provide the airflow necessary for both lift and propulsion. This is achieved by directing the airflow rearward of the craft. A splitter is then used to redirect approximately 30% of the airflow underneath the craft to provide the lift power. The remaining 70% of the airflow is used to propel the craft.

Figure 1 - Single-engine craft On a dual-engine craft (Figure 2), one engine and fan provide the lift power, while a 2nd engine and fan provide the forward thrust. Usually the lift engine and fan are mounted towards the front of the craft, with the thrust engine and fan mounted towards the rear.

Figure 2 - Dual-engine craft


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A single-engine craft is generally cheaper, and easier to construct than a dual-engine craft. A single-engine craft is a bit more limited, however. For example, with a dual-engine craft, it is possible to only turn on the lift engine, so as to manually maneuver the craft into and out of a trailer, or in other tight situations. In addition, dual-engine craft are generally able to go faster and hover higher, due to their dedicated engines for each task. The cheapest hovercraft, such as those offered from Universal Hovercraft (Appendix A) can be purchased for about $2000. These are sold in “kit” form (Figure 3) and must be built and assembled by the customer. Most of the parts are provided and the buyer must provide additional materials to assemble the unit. The cost of the additional materials, such as wood and skirt material, can easily increase the cost of the hovercraft to $3000 or more. While units like this do hover, they are typically very basic and lack many of the advanced features found on more expensive craft, such as: increased payload/seating capacity, increased top speed and acceleration, and the ability to travel in reverse.

Figure 3 - Economical "kit" hovercraft About $20,000 will buy a much more sophisticated craft, such as the Neoteric Hovertrek (Appendix A). This craft comes fully assembled and offers one main advantage over most other hovercraft: it has reverse thrust buckets. When the reverse buckets are not being used, they store neatly off to the side (Figure 4).

Figure 4 – Reverse buckets stored to side


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When activated, the reverse buckets swing into position to redirect the thrust airflow towards the front of the craft (Figure 5). If used while in motion, the craft is slowed down, but if used while stopped, reverse travel is enabled.

Figure 5 – Reverse buckets activated Highly advanced hovercraft such as the Universal Hovercraft 19XRW-Hoverwing (Appendix A) are available which continue to push the envelope of the hovercraft’s abilities by enabling the craft to take flight (Figure 6). This low level flight is made possible by the combination of a high power engine with airfoils on either side of the craft. This craft is incredibly expensive; priced at $85,000.

Figure 6 – Universal Hovercraft – Hoverwing

While there is quite a wide range of hovercraft available, there does not seem to be a mid-priced option with attractive features. The prices jump from only a couple thousand dollars with minimal features to twenty thousand dollars and more for the most technically advanced features. One goal of this project is to bridge that gap with a well featured, $10,000 hovercraft.


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CUSTOMER FEEDBACK AND SURVEY ANALYSIS A hovercraft survey was distributed among peers, recreational vehicle enthusiasts, and professionals in the hovercraft industry. A total of 13 responses were received. Table 1 shows a sorted list of what was most important to what was least important.

Table 1 – Customer Importance

The survey results show that the top features are durability, reliability, and maneuverability. Surprisingly, the results show that the ability to tow skiers/tubers is not a highly desired feature. Cargo space and low noise also rated low on the list. If any features will need to be eliminated, it will be the lowest two.

Survey Question Average Rating

Durability 4.54

Reliability 4.54

Maneuverability 4.31

Speed 4.23

Safety 4.15

Effective brakes 4.15

Cost 3.92

Ability to travel in reverse 3.15

Low noise 2.92

Cargo space 2.23

Ability to tow skiers/tubers 2.00


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INTERPRETATION OF SURVEY RESULTS

Table 2 Shows the QFD Importance. The customer importance column came directly from the survey results. This was how the Product Objectives were identified.

Table 2 – QFD Importance

Screen to cover the fans

Proper tip speed

Warning labels/fire extinguisher

4 cycle engine powered at 85%

Sturdy construction

Crash bumper

Hull constructed with fiberglass

seamed marine grade plywood

Reverse thrust buckets

Emergency stop

Mufflers

2ft3 cargo space

Aerodynamic design

Ability to seat 3 passengers

Rearview mirrors

Tow rope

Customer importance

Relative weight

Relative weight %

Durability 3 9 3 9 9 9 4.5 0.11 11%

Reliability 3 9 9 9 1 9 4.5 0.11 11%

Maneuverability 3 1 9 1 1 4.3 0.11 11%

Speed 3 1 1 3 9 1 4.2 0.11 11%

Safety 9 9 9 3 9 9 9 9 9 1 9 4.2 0.10 10%

Effective brakes 3 9 9 4.2 0.10 10%

Cost 1 1 1 3 3 1 9 3 1 3 1 3 1 1 3.9 0.10 10%

Ability to travel in reverse 3 9 3 3.2 0.08 8%

Low noise 9 3 9 2.9 0.07 7%

Cargo space 1 9 2.2 0.06 6%

Ability to tow skiers/tubers 3 9 9 9 2 0.05 5%


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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 are met. The product objectives will focus on the various aspects of the hovercraft. 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.


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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. 3. It will have rearview mirrors so the operator can verify the safety of the skier.


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DESIGN

DESIGN ALTERNATIVES AND SELECTION

The craft was originally designed to be a dual engine craft, with a separate engine and

fan for the lift and thrust systems. Due to the increased cost and reliability concerns of having two separate systems, the decision was made to use a single engine and fan for the thrust and lift systems. The completed thrust system can be seen in Figure 7.

Figure 7 – Thrust System Design Also, due to the rising cost and complexity of the project, the decision was made to remove the thrust buckets from the hovercraft. Alternatively, the hovercraft will slow by spinning 180 degrees and applying thrust to act in the opposite direction of travel, which will effectively slow the craft. The power to the engine can also be reduced to produce some skirt drag which will also stop the craft. If the engine is turned off completely, there will be a loss of pressure underneath and the craft will stop almost immediately. Due to the potential of injury to the occupants and damage to the craft, this procedure should be used in an emergency situation only.


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SELECTION OF AN ENGINE:

As with all things related to hovercraft, weight is very important. The first thing I did was look at different types of engines and how much horsepower they produced per pound. Diesel engines typically produce 0.1 HP per pound. Four-cycle gasoline engines typically produce 0.4 HP per pound, while two-cycle gasoline engines produce about 0.8 HP per pound. Turbine engines are far too expensive and impractical for the design of this craft. Aircraft piston engines are often used in hovercraft, but they are not readily available and are too expensive for this craft. From this information, it was obvious that either a two-cycle gasoline or four-cycle gasoline engine would be used. 2-Cycle Engines:

• Advantages: o Very light per HP o Small size per HP o Usually air cooled (therefore less weight and complexity)

• Disadvantages: o High noise levels o Less reliable and requires more maintenance o Small overall HP output o Fuel-oil mixture required o High vibration o More pollution o High RPM with narrow power band o Poor fuel economy

4-Cycle Engines:

• Advantages: o Quieter operation o More reliable with less maintenance o Larger overall HP output o No fuel-oil mixture required o Low vibration o Less pollution o Lower operating RPM with wider power band o Better fuel economy

• Disadvantages: o Heavier per HP o Larger size per HP o Usually liquid cooled (therefore more weight and complexity) o More expensive

From the information above, it was decided that a 4-cycle automotive engine would be used. These engines are readily available from junk yards for a few hundred dollars.

Hovercraft Thrust System and

Horsepower Required:

Since our hovercraft is to be operated on land and water, a phenomenon known as “Hump Drag” had to be considered. When a hovercraft is hovering in aover water, the force of the lift air displaces a volume of water equal to the craft weight. This depression creates a mound around the craft, which exerts tremendous drag on the craft as it tries to start moving. The maximum drag duuntil the craft reaches Hump Drag, the craft will be extremely sluggish and unresponsive. Once the craft has successfully climbed over the mound and is past Hump Drag, then the friction will be greatly reduced available to overcome Hump Drag, the craft speed on water will be limited to 5recommended to have at least twice as much static thrust as there is Hump Dragbe seen from Figure 8, our craft will experience a Hump Drag of 92.6 lbs at 8.1 mphAccording to Perozzo’s recommen

Additionally, hovercraft are generally categorized into two categories: cruising and racing craft. Cruising craft have fan static thrust to weight ratios of 10% or more, while racing craft have ratios of 25% or more. To go along with our customera craft which is fun to operate, we would like our craft to fit into the racing category, which means we’ll need a minimum of 300 lbs of thrust, based on a 1200 lb craft (including the weight of 3 passengers). Also, top speed on a hoavailable horsepower. We wanted our craft to be able to travel a minimum of 50 Based on our requirements for horsepower and top speed, IB6ZE engine out of a 1995 Mazda MX


Since our hovercraft is to be operated on land and water, a phenomenon known as “Hump Drag” had to be considered. When a hovercraft is hovering in a stationary position over water, the force of the lift air displaces a volume of water equal to the craft weight. This depression creates a mound around the craft, which exerts tremendous drag on the craft as it tries to start moving. The maximum drag during this stage is known as “Hump Drag.” until the craft reaches Hump Drag, the craft will be extremely sluggish and unresponsive. Once the craft has successfully climbed over the mound and is past Hump Drag, then the friction will be greatly reduced and the craft will begin to accelerate. If enough power is not available to overcome Hump Drag, the craft speed on water will be limited to 5recommended to have at least twice as much static thrust as there is Hump Drag

, our craft will experience a Hump Drag of 92.6 lbs at 8.1 mphrecommendation, we will need a minimum of 185 lbs of static thrust.

Figure 8 – Calculated Hump Drag

Additionally, hovercraft are generally categorized into two categories: cruising and

racing craft. Cruising craft have fan static thrust to weight ratios of 10% or more, while racing craft have ratios of 25% or more. To go along with our customer objectives of having a craft which is fun to operate, we would like our craft to fit into the racing category, which means we’ll need a minimum of 300 lbs of thrust, based on a 1200 lb craft (including the

Also, top speed on a hovercraft is limited only by drag and available horsepower. We wanted our craft to be able to travel a minimum of 50

Based on our requirements for horsepower and top speed, I ended up choosing to use a B6ZE engine out of a 1995 Mazda MX-3, as shown in Figure 9. This is a 1.6 liter, dual

David Louderback

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Since our hovercraft is to be operated on land and water, a phenomenon known as stationary position

over water, the force of the lift air displaces a volume of water equal to the craft weight. This depression creates a mound around the craft, which exerts tremendous drag on the craft as it

ring this stage is known as “Hump Drag.” Up until the craft reaches Hump Drag, the craft will be extremely sluggish and unresponsive. Once the craft has successfully climbed over the mound and is past Hump Drag, then the

and the craft will begin to accelerate. If enough power is not available to overcome Hump Drag, the craft speed on water will be limited to 5-10 mph. It is recommended to have at least twice as much static thrust as there is Hump Drag (1). As can

, our craft will experience a Hump Drag of 92.6 lbs at 8.1 mph. , we will need a minimum of 185 lbs of static thrust.

Additionally, hovercraft are generally categorized into two categories: cruising and racing craft. Cruising craft have fan static thrust to weight ratios of 10% or more, while

objectives of having a craft which is fun to operate, we would like our craft to fit into the racing category, which means we’ll need a minimum of 300 lbs of thrust, based on a 1200 lb craft (including the

vercraft is limited only by drag and available horsepower. We wanted our craft to be able to travel a minimum of 50-60 mph.

ended up choosing to use a . This is a 1.6 liter, dual


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overhead cam, fuel-injected 4-cylinder engine. This engine produces 105 HP at 6200 RPM and 100 ft-lbs of torque at 3700 RPM.

Figure 9 – Engine Donor – 1995 Mazda MX-3


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FAN SELECTION:

Fan vs. Propeller:

Once the engine was selected, it was time to determine the propulsion device which would be driven by the engine. A decision had to be made as to use either a fan or a propeller. Propeller:

• Advantages: o More thrust per HP – generally 5-8 lb/hp o Faster throttle response

• Disadvantages: o Very loud due to higher tip speed o Higher thrust line due to larger size o If damaged, entire prop must be replaced o High blade erosion

Fan:

• Advantages: o Quieter operation o Lower thrust line due to smaller size o Individual blades can be replaced if damaged o Less blade erosion

• Disadvantages: o Less thrust per HP – generally 3-6 lb/hp o Slower throttle response

Based on the information above, I chose to use a fan instead of a propeller. This would allow us to meet our customer needs of having a quiet craft which is reliable and easy to maintain.

Hovercraft Thrust System and

Diameter:

The next decision to be made was the diameter of the fan. In terms of efficiency, the larger the fan, the better – as long as power is available thorsepower required to rotate a fan increases as the cube of the rpm. Too small of a fan will allow the engine to over rev, while too large of a fan will cause the engine to bog down. One downside of using a large fan is that it raises the thrust line of the craft. This force causes the nose of the craft to dive under acceleration. Larger diameter fans will typically operate at lower rpm, thereby reducing the tip speed and noise. It is recommended to keep tip speeunder 600 ft/sec (1). This limit results in reduced noise, reduced danger from high speed rotation, and reduced blade erosion. Based on all of the information above, the fan that I have selected is 42” in diameter and has a max rpm of 2500. The fan is manufactured by Hascon Engineeringthat at 2500 rpm, our fan tip speed will be 458 ft/sec. This number is far below the recommended 600 ft/sec maximum.

Number of Fan Blades:

The next thing to be determined was the number of fan blades on the fan. The number can vary anywhere from 3 to 16. More blades are better for creating static pressure for lift purposes. Fewer blades are better for creating compromise had to be made to accommodate both the thrust and lift systems. A 12hub with 12 blades was chosen for our craft. This gives the option to use all 12 blades for maximum lift pressure, or we can usminimum lift pressure is still maintained.


The next decision to be made was the diameter of the fan. In terms of efficiency, the as long as power is available to spin the fan at the proper rpm. The

horsepower required to rotate a fan increases as the cube of the rpm. Too small of a fan will allow the engine to over rev, while too large of a fan will cause the engine to bog down. One

an is that it raises the thrust line of the craft. This force causes the nose of the craft to dive under acceleration. Larger diameter fans will typically operate at lower rpm, thereby reducing the tip speed and noise. It is recommended to keep tip spee

. This limit results in reduced noise, reduced danger from high speed rotation, and reduced blade erosion.

Based on all of the information above, the fan that I have selected is 42” in diameter and a max rpm of 2500. The fan is manufactured by Hascon Engineering. Figure 10

that at 2500 rpm, our fan tip speed will be 458 ft/sec. This number is far below the recommended 600 ft/sec maximum.

Figure 10 – Fan Tip Speed

The next thing to be determined was the number of fan blades on the fan. The number can vary anywhere from 3 to 16. More blades are better for creating static pressure for lift purposes. Fewer blades are better for creating thrust. With our single engine craft, a compromise had to be made to accommodate both the thrust and lift systems. A 12hub with 12 blades was chosen for our craft. This gives the option to use all 12 blades for maximum lift pressure, or we can use 6 or 9 blades for increased thrust, so long as the minimum lift pressure is still maintained.

David Louderback

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The next decision to be made was the diameter of the fan. In terms of efficiency, the o spin the fan at the proper rpm. The

horsepower required to rotate a fan increases as the cube of the rpm. Too small of a fan will allow the engine to over rev, while too large of a fan will cause the engine to bog down. One

an is that it raises the thrust line of the craft. This force causes the nose of the craft to dive under acceleration. Larger diameter fans will typically operate at lower rpm, thereby reducing the tip speed and noise. It is recommended to keep tip speed

. This limit results in reduced noise, reduced danger from high speed

Based on all of the information above, the fan that I have selected is 42” in diameter and . Figure 10 shows

that at 2500 rpm, our fan tip speed will be 458 ft/sec. This number is far below the

The next thing to be determined was the number of fan blades on the fan. The number can vary anywhere from 3 to 16. More blades are better for creating static pressure for lift

thrust. With our single engine craft, a compromise had to be made to accommodate both the thrust and lift systems. A 12-blade hub with 12 blades was chosen for our craft. This gives the option to use all 12 blades for

e 6 or 9 blades for increased thrust, so long as the


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Blade Pitch:

An additional variable with the fan is the pitch of the blades. The pitch on the chosen fan can be adjusted from 20° to 50°. Altering the pitch is one way of properly loading the engine so that it doesn’t over rev. Increasing the pitch increases the CFM output of the fan, but it also drastically increases the amount of HP to drive the fan. As shown in Figure 11, at a 40° blade pitch, our engine will have enough HP to spin the fan its full 2500 RPM. Increasing the pitch to 45°, however, means that we’ve only got enough power to spin the fan to 2250 RPM. Increasing the pitch further to 50°, and our 105 HP engine can only spin the fan 2000 RPM. It would take nearly 200 HP to spin the fan 2500 rpm with a 50° pitch.

Figure 11 – Blade Pitch vs. HP Absorbed


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TOP SPEED CALCULATIONS:

Now that the engine and fan have been selected, the top speed of the hovercraft can be estimated. The top speed of is determined when the available thrust cannot overcome the increasing drag. The fan generates the most thrust with the craft at rest. The dynamic thrust decreases as the speed of the craft increases, due to the air hitting the blades at a smaller and smaller angle. Figure 12 shows the decreasing dynamic thrust with relation to craft speed.

Figure 12 – Dynamic Thrust vs. Speed To determine the top speed, the drag must also be determined. When operating on a smooth surface, there are two main types of drag: form drag and momentum drag. Form drag is the most dominant type of drag and is determined by the physical size and shape of the craft. A form factor of 0.5 is assumed (1). The momentum drag is caused by static air under the craft coming into contact with the moving ground underneath. Figure 13 shows the types of drag vs. the craft speed. Momentum drag is the linear red line. Form drag is the higher, green line. The total drag (form + momentum) is depicted by the blue line at the top.


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Figure 13 – Total Drag vs. Speed Now that the total drag and dynamic thrust have been plotted, the graphs can be combined to show the theoretical top speed, as shown by Figure 14. The intersection of the two lines shows that our top speed should be 68.6 mph.

Figure 14 – Total Drag vs. Dynamic Thrust = Top Speed


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POWER TRANSMISSION:

The power transmission system consist of the belt and sprockets, drive shafts with keyways and retaining ring grooves, bearings, and the jaw coupling. These components are shown in Figure 15.

Figure 15 – Power Transmission Components


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Belt and Sprocket Design:

A synchronous belt tooth was chosen because it offers many advantages over V-belts, such as a higher torque capacity and resistance to slipping, even when wet. Within the synchronous belt family, many options further exist. Standard timing belts have a trapezoidal tooth design and are prone to jumping teeth. The HTD curvilinear belt design was certainly an improvement over the standard timing belt, but still was not ideal for high power applications. The belt that I have chosen, due to its high strength and superior features (such as greater flexibility and moisture resistance), is the Gates Poly Chain GT Carbon belt. This belt is so strong that it is advertised as being a full replacement for roller chains. Based on the hp and rpm requirements, an 8mm tooth pitch will be used. Figure 16 shows the dimensions of this belt profile.

Figure 16 – Belt Profile

Engine power is 105 HP, so based on a service factor of 1.4, the design HP is 147 HP. The service factor of 1.4 was chosen due to the fact that the power source is a multiple cylinder internal combustion engine, the system will experience intermittent service (up to 8 hours daily), and the system is used to power a fan. The max engine rpm is 6500 and the max fan rpm is 2500, so a 2.6 reduction ratio will be needed. Due to the availability of standard parts, a reduction ratio of 2.54 is being used. The smaller sprocket will have a pitch diameter of 2.81” and the larger sprocket will have a pitch diameter of 7.12”. The center distance between these two sprockets will be 20.44” and the belt will have a pitch length of 56.7”. The two sprockets and belt can be seen in Figure 17. Based on the 2.81” sprocket rotating at 6500, the maximum belt speed has been calculated to be 4777 ft/min. This is far below the manufacturer’s recommended maximum of 6500 ft/min. Using the manufacturer supplied charts, a 36 mm width was chosen for the sprockets and belt. The smaller sprocket would have the lowest hp capacity (due to the tighter radius and subsequent fewer teeth in engagement), so taking a 36 mm wide sprocket and correcting for the speed down ratio and belt length correction factor, the rated power is 161 HP. This is higher than the design hp of 147, so the system has been proven to be sufficiently strong.


20

Figure 17 – Layout of sprockets and belt

Drive Shaft Calculations:

Three separate, solid steel drive shafts will be used in the drive train. Figure 18 shows the layout of the drive shafts. The first drive shaft (blue/green in the picture) will be used to connect the engine flywheel to the jaw coupling, and will be 1.125” in diameter. The other two drive shafts (red and yellow in the picture) will be stepped from 1.125” up to 1.5”. The purpose of the step is to locate the shafts against the bearings. There is a 0.03” sharp fillet at radius of step, producing a stress concentration factor of 2.5. Power is transmitted from the drive shaft to the sprockets via a 3/8” sled runner key and keyway, producing a stress concentration factor of 1.6. Lastly, the sprockets are held in place axially with retaining rings. The retaining ring groove in the shaft produces a stress concentration factor of 3. All of these different stress concentration factors at different locations were taken into account when determining the drive shaft sizes. Additionally, a design factor of 2.0 was used, due to an average level of confidence in the data for material strength and loads.


21

Figure 18 – Drive Shaft Layout

At 6500 RPM, the engine generates 1018 in-lbs of torque. Acting on the smaller, 2.81” sprocket, this creates 724.3 lb of tension in the belt. When this tension acts on the larger, 7.12” sprocket, it creates 2578.6 in-lbs of torque on the fan shaft. The maximum bending moment on the fan shaft is 1000.2 in-lb. Figures 19 shows a side profile of the fan shaft and Figure 20 shows the shear and bending moment diagram for this shaft.

Figure 19 – Side Profile of Fan Shaft


22

Figure 20 – Shear Force and Bending Moment Diagram for Fan Shaft

1020 cold rolled steel was chosen for the drive shafts due to its high strength and relatively low cost. A reliability factor of 99% was used = 0.81. A size factor of 0.875 was used. Due to the three separate shafts and numerous times the drive shaft size had to be calculated (due to varying stress concentration factors at various locations), a spreadsheet was made to ensure consistency across the numerous calculations. The fan shaft calculations can be seen below and a view of the spreadsheet is in Table 3.

� = �32�� 2 + 34 ( �� )2�1/3

� = �32 ∗ 2� �3 ∗ 1000.221262.5 �2 + 34 ( 257964000)2�1/3

� = 1.436 "�


23

Table 3 – Fan Shaft Spreadsheet Calculations

Bearing Selection:

Two pillow block bearings will support each sprocket shaft. They were originally spaced 4” on each side of sprocket, but reduced to 3” to minimize the bending moment on the drive shaft. Due to high rpm of shafts, ball bearings will be used. Selected bearings have radial capacities of over 1500 lbs and axial capacities of over 500 lbs. Figure 21 shows the selected bearings.

Figure 21 – Pillow Block Bearing

Input Data:

Shaft material specification 1020 Cold rolled steel

Tensile strength Su 75000 psi

Yield strength Sy 64000 psi

Basic endurance strength Sn 30000 psi fig 5-8

Size factor Cs 0.875 fig 5-9

Reliability factor Cr 0.81 table 5-1

Modified endurance strength sn' 21262.5 psi

Stress concentration factor Kt 3 retaining ring groove

Design factor N 2

Shaft loading Data: Bending and Torsion

Bending moment components Mx 0 My 1000.2

Combined bending moment M 1000.2 lb in

Torque T 2579 lb in

Minimum shaft diameter D 1.436 in


24

Jaw Coupling Selection:

A jaw coupling was chosen to dampen some of the vibrations from the engine and also to absorb any small variation in shaft alignment due to engine torque. This jaw coupling will help to reduce stress on the bearings. The coupling is composed of two shells with a 7/8” urethane spider on the inside. This will be able to transmit 1850 in-lbs of torque at 7500 rpm, which is more than the 1018 in-lbs of torque at 6500 rpm generated by the engine. Figures 22 and 23 show the jaw coupling in more detail.

Figure 22 – Jaw coupling shell

Figure 23 – Jaw coupling spider


25

THRUST DUCT AND STATOR BLADES:

The thrust duct not only serves as a blade guard, but also increases the thrust by 15-20%, if done properly. The inlet radius of the duct needs to be about 12% of the duct diameter to ensure smooth airflow (2). Additionally, the fan blade tip clearance must not exceed 1/2”. I am aiming for a tip clearance of 1/8” in this craft. The stator blades are placed close behind the fan blades, and they help to straighten out the airflow after passing through the fan. There must be either one more or one less stator blade than there are fan blades. If the number of blades were equal, each time a fan blade passes a stator blade, there would be a pressure disturbance. Having a different number of stator blades helps to break up this vibration. The thrust duct and stator blades can be seen in Figure 24.

Figure 24 – Thrust Duct and Stator Blades


26

SCHEDULE AND BUDGET The schedule begins on November 24th, with the Proof of Design Contract. The project takes place over 28 weeks and ends on May 30, when the final report is due. Table 4 shows some of the key milestone dates.

Table 4 – Milestone Dates

A preliminary budget was prepared which included all materials and parts which would be purchased. Table 5 shows a condensed version of the preliminary budget. After any sponsor money is used, the remaining cost will be divided equally among the three team members. Due to the complexity of the project, this budget ended up being grossly underestimated. We actually spent about $4000, with an additional $3000 in parts and materials donated, making the grand total $7000, nearly three times our original estimate.

Table 5 – Preliminary Condensed Budget

Task Team Member Responsible Target Date

Determine Engines to Be Used All December 13th

Determine Fans to be Used All December 20th

Finalize Gear Ratio Design David Louderback December 27th

Finalize Lift System Design Kelly Knapp January 3rd

Finalize Thrust/Braking System Design David Louderback January 10th

Finalize Steering System Design Kelly Knapp January 17th

Finalize Throttle/Controls Design Jeremy Siderits January 24th

Finalize Hull Design Jeremy Siderits January 31st

Order Components with Extended Lead Time All January 31st

Design Freeze All January 31st

Finalize Design and BOM All February 7th

Order Remaining Components All February 28th

Oral Design Presentation All February 28th

Design Report All March 7th

Complete Component Fabrication All March 14th

Complete Assembly of Hovercraft All May 9th

Demo for Advisor All May 9th

Demo to Faculty All May 16th

Oral Final Presentation All May 23rd

Final Report Due All May 30th

Lift System 525

Thust System 600

Body 520

Steering System 150

Electrical 200

Miscellaneous 375

Total 2370


27

FABRICATION

First the entire team worked to construct the Hovercraft body and frame.

Figure 25 – Hovercraft Basic Frame


28

Figure 26 – Hovercraft Frame Once the frame was mostly complete, the craft was relocated out of my garage and up to Blue Ash Tool and Die, where Jeremy Siderits and Kelly Knapp would finish the frame and steering systems.

Figure 27 – Hovercraft being relocated


29

This enabled me to build the drivetrain components separately in my garage. First I set out to construct the thrust duct. Two cylinders were made out of aluminum flashing and a expandable liquid foam was poured in place. After the foam hardened, the flashing was removed and the foam was sanded and shaped to the final dimensions of the thrust duct.

Figure 28 – Thrust Duct Mold


30

Figure 29 – Thrust Duct with Inner Flashing Removed

Figure 30 – Completed Thrust Duct Then I got to work welding and painting the engine frame. This was made primarily of 1” square tubing with 1/8” wall thickness, 1020 cold rolled steel.


31

Figure 31 – Engine Frame Pieces Once I was able to mount the engine on the frame, I constructed a mock platform with the exact dimensions available for the engine bay and started working on getting the engine running. This was a very challenging task because the car’s computer had to be fooled into thinking the engine was still inside the car. Every connection and sensor had to be hooked up just right.


32

Figure 32 – Engine Mounted on Frame Once the engine was running I began to construct and weld the fan and drivetrain frame. Again, this was made primarily 1” square tubing with 1/8” wall thickness. The material is 1020 cold rolled steel.


33

Figure 33 – Fan Frame being Welded


34

Figure 34 – Completed Fan Frame Mounted with Engine The engine was then installed in the craft and final connections were made. The next thing that I did was constructed a trailer to transport the craft. I started with a 4x8 foot trailer and modified it to be 7x12 feet. It is a tilt trailer so the bed can be tilted for easy drive off. To be loaded, a winch will be added to pull the craft onto the trailer backwards, for better weight distribution.


35

Figure 35 – Trailer Base

Figure 36 – Trailer Modifications


36

Figure 37 – Completed Trailer with Hovercraft being relocated again

Figure 38 – 42” Fan Mounted to Hub


37

Figure 39 – Fan being test fit on Hovercraft


38

TESTING Unfortunately the craft has not yet been tested. The bag skirt still needs to be installed in order to make the craft operational. The thrust of the hovercraft will be tested by tying the craft to a tree with a spring scale and operating it at full throttle. Based on these results, we can then experiment with the number of fan blades and the pitch of each blade to achieve the best results.


39

CONCLUSION The thrust system was designed sufficiently powerful enough for this craft. Acceleration is adequate and the top speed goal of 50-60 mph was exceeded and increased to 68.5 mph. This project ended up being a tremendous amount of work and we simply ran out of time to get it finished. The amount of work to go is rather small, however, so it should be up and running soon.


40

REFERENCES 1. Perozzo, James. Hovercrafting as a Hobby. Bend, OR : Maverick Publications, 2001. 2. Fitzgerald, Christopher and Wilson, Robert. Light Hovercraft Design. Foley, AL : The Hoverclub of America, Inc., 1995. 3. Mott, Robert L. Machine Elements in Mechanical Design. Upper Saddle River : Prentice Hall, 2004. 4. Caldwell, Laura. Course Documents by Professor Laura Caldwell. [Online] July 2007. [Cited: August 16, 2007.] http://homepages.uc.edu/~caldwelm/Courses/SrSeminar/overview.docx . 5. Neoteric Hovercraft. 4 Passenger Recreational Specifications. Neoteric Hovercraft. [Online] Neoteric Hovercraft. [Cited: 09 20, 2010.] http://neoterichovercraft.com/specifications/4Lspecifications.htm. 6. 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. 7. —. 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. 8. 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. 9. Springer, Ryan. Hovercraft Manufacturer. Rockford, IL, 09 29, 2010. 10. Baker, Larry and Kathleen. Power Sports Enthusiasts. Cincinnati, OH, 10 01, 2010. 11. Simons, Chuck. Power Sports Sales Specialist. Cincinnati, OH, 10 01, 2010. 12. Puerto Penasco, Rocky Point. [Online] 10 12, 2010. [Cited: 11 26, 2010.] http://www.puertopenasco.org/hovercraft.htm. 13. Hoverstar LC. Hovertechnics, Inc. [Online] 2007. [Cited: 11 26, 2010.] http://www.hovertechnics.com/recreation/hoverstarlcfeatures.htm.

Appendix A1

APPENDIX A – RESEARCH DOCUMENTATION 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 A2

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 two-stroke 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 A3

Related Products:

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. A single 10 hp Tecumseh horizontal shaft engine turns a two blade 36-inch 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.

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

http://www.hovercraft.com/content/index.php?main_page=index&cPath=33_40 9/29/10

UH-10F Hovercraft

Appendix A4

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)

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/4Lspecifications.htm 9/20/10 Hovertrek,

Neoterichovercraft.com, Neoteric Hovercraft

Appendix A5

Universal Hovercraft is proud to offer the UH-19XRW 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.

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.php?main_page=index&cPath=2 , 9/29/10, 19XRW Hoverwing, hovercraft.com, Universal Hovercraft

Appendix B1

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. 1 = low importance 5 = high importance

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.

AVG

Safety 1 2 3(5) 4(1) 5(7) N/A 4.15

Durability 1 2 3(1) 4(4) 5(8) N/A 4.54

Reliability 1 2 3(1) 4(4) 5(8) N/A 4.54

Maneuverability 1 2 3(1) 4(7) 5(5) N/A 4.31

Effective brakes 1 2(1) 3(3) 4(2) 5(7) N/A 4.15 Ability to travel in

reverse 1 2(3) 3(6) 4(3) 5(1) N/A

3.15

Low noise 1(1) 2(5) 3(3) 4(2) 5(2) N/A 2.92

Cargo space 1(4) 2(4) 3(4) 4 5(1) N/A 2.23

Speed 1(1) 2(1) 3 4(3) 5(8) N/A 4.23 Ability to tow skiers/tubers

1(6) 2(2) 3 4(4) 5 N/A 2.00

Cost 1(1) 2(1) 3(2) 4(3) 5(6) N/A 3.92

Appendix C1

APPENDIX C – QFD AND PRODUCT OBJECTIVES

Screen to cover the fans

Proper tip speed

Warning labels/fire extinguisher

4 cycle engine powered at 85%

Sturdy construction

Crash bumper

Hull constructed with fiberglass

seamed marine grade plywood

Reverse thrust buckets

Emergency stop

Mufflers

2ft3 cargo space

Aerodynamic design

Ability to seat 3 passengers

Rearview mirrors

Tow rope

Customer importance

Relative weight

Relative weight %

Safety

99

93

99

99

91

94.2

0.10

10%

Durability

39

39

99

4.5

0.11

11%

Reliability

39

99

19

4.5

0.11

11%

Maneuverability

31

91

14.3

0.11

11%

Effective brakes

39

94.2

0.10

10%

Ability to travel in reverse

39

33.2

0.08

8%

Low noise

93

92.9

0.07

7%

Cargo space

19

2.2

0.06

6%

Speed

31

13

91

4.2

0.11

11%

Ability to tow skiers/tubers

39

99

20.05

5%

Cost

11

13

31

93

13

13

11

3.9

0.10

10%

Abs. importance

1.714.901.032.283.572.274.163.831.960.950.601.060.951.820.5531.6

Rel. importance

0.050.160.030.070.110.070.130.120.060.030.020.030.030.060.02

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3 =

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Appendix C2

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

are 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 fram

e.

6. The hull will be constructed using ½” marine grade plywood coated with an epoxy primer and an enam

el 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 fram

e 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 movem

ent of the craft.

4. A turning radius of zero is achievable with minimal thrust but increases with speed.

Appendix C3

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 requirem

ents 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 dam

age

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 C4

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%):

4. A tow rope will be able to be attached to the back of the craft.

5. In order to legally tow a skier, the craft will be able to seat 3 passengers.

6. It will have rearview mirrors so the operator can verify the safety of the skier.

Appendix D1

APPENDIX D – SCHEDULE AND BUDGET Schedule (proposed in yellow, actual in orange):

Jeremy Siderits, Kelly Knapp, Dave Louderback Tasks in black text are equally shared by the group members

DA

TE

11

/21

- 1

1/2

7

11

/28

-1

2/4

12

/5 -

12

/11

12

/12

- 1

2/1

8

12

/19

- 1

2/2

5

12

/26

- 1

/1

1/2

- 1

/8

1/9

- 1

/15

1/1

6 -

1/2

2

1/2

3 -

1/2

9

1/3

0 -

2/5

2/6

- 2

/12

2/1

3 -

2/1

9

2/2

0 -

2/2

6

2/2

7 -

3/5

3/6

- 3

/12

3/1

3 -

3/1

9

3/2

0 -

3/2

6

3/2

7 -

4/2

4/3

- 4

/9

4/1

0 -

4/1

6

4/1

7 -

4/2

3

4/2

4 -

4/3

0

5/1

- 5

/7

5/8

- 5

/14

5/1

5 -

5/2

1

5/2

2 -

5/2

8

5/2

9 -

6/4

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) 2

2

Long delivery components 31

31

Major Component Design freeze 31

31

Final hovercraft design 21

3

Hovercraft BOM 21

18

Order hovercraft components 28

18

Oral design presentation 28

3

Design report 7

18

Component fabrication 14

Assembly 9

Demo to advisor 9

Demo to faculty 16

Oral final presentation 23

Final report due 30

Appendix D2

Original Hovercraft Budget:

System Component Price

Lift Bag Skirt $125.00

Lift Engine $100.00

Lift Fan $250.00

Muffler $50.00

Thrust Thrust Engine $100.00

Thrust Fan $350.00

Belt System $50.00

Reverse Buckets $50.00

Muffler $50.00

Body 1/2" thick marine grade plywood $150.00

misc wood $100.00

Fiberglass and resin $125.00

In-line Seating $40.00

Paint $75.00

Warning Labels $10.00

Duct Screen $20.00

Steel Tube Donated

Steering Handlebars $100.00

Rudders $50.00

Electrical Temperature Gauge $25.00

Temperature Gauge $25.00

Tachometer $25.00

Tachometer $25.00

Battery $50.00

Alternator $50.00

Misc Misc parts and hardware $375.00

$2,370.00

Material used for the bottom of the hull

Handlebar system

Temperature guage for lift engine

Temperature guage for thrust engine

RPM guage for lift engine

RPM guage for thrust engine

Joint support and waterproofing material

Enamel based paint for superior protection

Keep hand away, hot, electrical hazard

Fabric and support for seating

Hovercraft Budget

4-stroke engine

Muffler system

Mult-blade fan

Rudder system

Belt and pulleys

Fabricated fiberglass shell

Material used for ribs and top of the hull

Description

Vinyl coated nylon fabric

4-stroke engine (Discounted)

Multi-blade fan

Muffler system

Wire sceen for fan protection

N/A

Tube stock for engine support

12v Battery

System to charge battery

Total

Hovercraft thrust system and drivetrain

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