Catapult Crossfire

1
In order to figure out the lengths of the Fourbar links, it was necessary to find the angle of the table rotation relative to the span of the cups. NX aided in finding the solution as displayed by the trace in the screen capture. Acknowledgments ME 371 Group 10 The purpose of this project was to build a functioning prototype (Catapult Crossfire), which involved all of the design techniques learned in the ME 371 lecture. 16 Degree Trace Colin Perrault Charles Ferriera Ross Dudgeon Brendan Brown Motivation Design Components Methods By using NX CAD and various calculations, we were able to limit our trial and error. This sped up both the design process and physical creation of Catapult Crossfire. It was also imperative to select the proper materials for construction especially when welding. Conclusions Machine Shop Some of the tools and machines used during the project, were: lathe, mill, drill press, various powers tools (nail gun, dremel, drill, etc…) and miscellaneous hand tools. Fourbar Linkage The Fourbar Linkage controls the angle of the table. The table rotates due to the horizontal motion of the Fourbar linkage when the user pushes or pulls the lever bar. Overdrive Gear Setup The two gears are connected via a bike chain and is an overdrive setup. This means the output velocity will be greater than the input. Cam The cam was designed with a large amount of dwell with a steep rise and fall. This creates the launching feature of the catapult. The design was later found to be similar to that of a trip hammer. Design Theory = = 2 3 4 5 Compound Gear Train Output Simple harmonic Rise = 2 1 − cos Linkage Synthesis = − 1 1 2 2 + 3 3 Several methods were used in order to design and construct Catapult Crossfire: Rough hand drawn sketch Calculations by hand NX CAD The design theory was based upon numerous equations learned in the ME 371 lecture. Relevant equations are given below. We would like to thank Roy, Ken and the rest of the Machine Shop employees for their help and cooperation.

Transcript of Catapult Crossfire

Page 1: Catapult Crossfire

In order to figure out

the lengths of the

Fourbar links, it was

necessary to find the

angle of the table

rotation relative to

the span of the cups.

NX aided in finding

the solution

as displayed by the

trace in the screen

capture.

Acknowledgments

ME 371

Group 10

The purpose of this project was to build a

functioning prototype (Catapult Crossfire),

which involved all of the design techniques

learned in the ME 371 lecture.

16 Degree Trace

Colin Perrault

Charles Ferriera

Ross Dudgeon

Brendan Brown

Motivation Design Components

Methods

By using NX CAD and various

calculations, we were able to limit our

trial and error. This sped up both the

design process and physical creation of

Catapult Crossfire. It was also

imperative to select the proper

materials for construction especially

when welding.

Conclusions

Machine Shop

Some of the tools

and machines used

during the project,

were: lathe, mill,

drill press, various

powers tools (nail

gun, dremel, drill,

etc…)

and miscellaneous

hand tools.

Fourbar Linkage

The Fourbar Linkage controls the

angle of the table. The table

rotates due to the horizontal

motion of the Fourbar linkage

when the user pushes or pulls the

lever bar.

Overdrive Gear Setup

The two gears are connected via

a bike chain and is an overdrive

setup. This means the output

velocity will be greater than the

input.

Cam

The cam was designed with a

large amount of dwell with a

steep rise and fall. This

creates the launching feature

of the catapult. The design was

later found to be similar to

that of a trip hammer.

Design Theory

𝑚𝑣 = 𝜔𝑜

𝜔𝑖= −

𝑁2

𝑁3−

𝑁4

𝑁5

Compound Gear Train Output

Simple harmonic Rise

𝑆 =ℎ

21 − cos

𝜋𝜃

𝛽

Linkage Synthesis

𝑎 = −𝛼1 − 𝛽1 𝑐

𝛼2 − 𝛽2 + 𝑐 𝛼3 − 𝛽3

Several methods were used in order to design

and construct Catapult Crossfire:

• Rough hand drawn sketch

• Calculations by hand

• NX CAD

The design theory was based upon

numerous equations learned in the ME

371 lecture. Relevant equations are

given below.

We would like to thank Roy, Ken and

the rest of the Machine Shop

employees for their help and

cooperation.