Hovercraft body and frame - UC DRC Home

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.
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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
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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.
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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.
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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
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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.
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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.
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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 (10). It will
have rearview mirrors so the operator can verify the safety of the skier.
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Hovercraft: Body and Frame
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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
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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
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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).
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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
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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.
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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.
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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
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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.
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Hovercraft: Body and Frame
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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
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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.
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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
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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.
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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