Design Review Report
LevTech
The purpose of the formation of LevTech is a cooperative design and production
plan to bring to development a single person hover scooter, at a reasonable price, that
meets safety standards and production requirements for widespread distribution.
This hovercraft will be designed for a market of people from ages 12 and up, with
parental supervision suggested for younger children. There are several such designs
currently on the market, but as they are somewhat expensive, the goal of LevTech is to
make this technology available to a broader range of consumers.
The method by which team LevTech came to decide on a hovercraft for our final
project is the same method that will be used for all subsequent major decisions. Each
team member developed at least one concept for group review. The respective merits and
faults of each project were then weighed. Factors taken into consideration included ease
of implementation, cost, usefulness, originality and the overall aesthetic of each idea.
Once discussion of each idea was completed, the number of ideas was narrowed based
upon group consensus. There was further discussion of the three final ideas, and of the
final three ideas, the hovercraft was the only one that strongly appealed to all group
members. After investigating, the difficulty involved in the control systems for the initial
idea of a remote control craft, one group member suggested a change to a personal rideon craft; the change was agreed upon by discussion and majority vote. All remaining
decisions regarding design, control, aesthetic, and budget will be decided by group
discussion and consensus. In the interest of time, when consensus cannot be reached, all
group members have agreed to abide by a majority rule vote.
Specifications:
Size:
The craft shall be approximately 4 feet long by 3 feet wide, with a height of about
3 feet. The un-laden weight shall be approximately 50 pounds.
Cost:
The overall budget for the prototype of this project is $400, with $300 of that
being contributed by our primary sponsor, Columbia University, and the last $100 being
optional discretionary funds provided by the group members.
Power:
The craft shall draw both its thrust force and lift force from gas-powered leaf
blower engines, with approximately 1 horsepower for lift and at least 5 horsepower for
thrust. The output of the lift fan shall be fixed, adjusted to provide approximately ½ “ of
ground clearance for the weight of the given rider. The thrust fan, mounted on the aft of
the hovercraft, will be throttled by the user using a handle mechanism attached to the
steering device.
Control:
The craft will be controlled by a rudder system comprised of 2-3 blades mounted
on the rear of the thrust fan and mounted to the frame of the fan. The blades will be
directed by the rider using either a cable steering mechanism or an outboard boat type
steering mechanism.
This project is scheduled for a 14 week period from initial concept, due to the
constraints of a semester. The production schedule is as shown in the Gantt Chart, with
parts being ordered as soon as possible following the design finalization in order to allow
for an adequately long manufacturing period. The essentials of our schedule are as
follows:
Concept Selection: Group decision about direction and goals of design project.
Research: Literature and concept search for similar designs and applicable patents/
publications.
Design: Implementation of research and creative inputs to formulate first iteration of
final design.
Purchasing: Ordering parts, managing budget, scavenging parts wherever available.
Production: Manufacture and assembly of prototype
Testing: Threshold and performance analysis of prototype
Presentation: Demonstration of final prototype to judgment panel.
Literature Search (Internet, Patent, TV, etc.)
Universal Hovercraft (www.hovercraft.com)
Universal Hovercraft offers two designs for RC models. GH-2 uses two ducts for
propulsion – one for lift in the front and the other for thrust located in the back. The lift
duct blows air underneath to create air cushion enclosed by a skirt. The thrust fan propels
the boat forward while the rudder behind the thrust fan is in place to steer it.
The GH-1 hovercraft uses one thrust duct unit. The duct blows 1/3 to 1/2 of its air
underneath the craft to create an air cushion; the other half blows toward the rear sending
the craft forward. Like the GH-2, thrust air is used for steering. This system would allow
or a lighter payload and hence less expensive fan-motor system is required for lift and
thrust
UH-10F Entry Level: A single 10 hp Tecumseh horizontal shaft engine turns a
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 dozens
of schools and colleges throughout the world. The body is 5’ by 10’ and can carry 250
lbs of payload.
UH-6F Trainer is a simple 6’ by 3’, 65 lbs hovercraft that can carry 150 lbs of
payload. It is based on one duct system, as GH-1 was, using a portion of the sucked air
for lift and the rest for thrust. It runs on a 3-5 hp gas engine or a 1-2 hp electric motor,
attaining a max speed of 15 mph. Joystick is mechanically attached to rudders in the
back for steering.
Problem Analysis and Conclusions
Stability
One of the most difficult challenges LevTech has had to address is the issue of
balancing the Cialatron. Our design consists of the entire hovercraft, riding on a
relatively small cushion of air that is providing lift. Since this lift is generated at the
center of our vehicle, it may have a tendency to tip. As a team, we decided that the best
way to minimize this tendency is to distribute the weight of the hovercraft to the outer
perimeter as efficiently as possible.
To do this, our team developed out outrigger system that is essentially a plywood
frame, on which our entire assembly will rest. The skirt will be attached directly to this
outrigger system, which we believe will adequately distribute our weight to the outer
edges.
If the problem of stability still poses an issue after installing the outrigger system,
we will apply counterweights to balance the hovercraft as accurately as possible.
Control
An adequate control system is vital to the operation of the Cialatron. To
manipulate the flow of air out of the thrust fans we decided two rudders would provide
the most control. High strength cables attached to the rudders and also to the bottom
edges of an I-shaped bar will give the user some means of operating the rudders. By
turning the upper cross beam of the I-bar, the left and right cables will be wound in one
direction pulling both rudders in the same path. The mechanical advantage of the handles
on the I-beam will make it easier for operation by younger customers.
Safety
LevTech has made safety one of our primary concerns. Several safety problems
are inherent in the design and need to be addressed. First, since we are including a gaspowered motor, that will generate a certain amount of heat, we need to install a heat
shield that will protect the user from burns. The motor will be turning a large fan at a
very high RPM. We are encasing the fan in a protective gate that will prevent any
accidents involving the fan.
Another concern that was brought up during our initial analysis of the feasibility
of the project, is an innocent bystander being run over by the Cialatron. Though most of
this problem will be minimized by safe operation procedures, we will not allow any sharp
corners that could wound someone who is accidentally hit.
Additionally, an automatic cutoff switch will sever power to the lift and thrust
motors, which will stop the Cialatron if the user were to fall off.