design of a low velocity railgun jason fodstad thomas morris julie duryee vardaan chawla final...
TRANSCRIPT
Design of a Low Velocity Railgun
Jason Fodstad
Thomas Morris
Julie Duryee
Vardaan Chawla
Final Presentation – MSE 4021
April 26, 2005
Faculty Advisor: Dr. Naresh Thadhani
The Capacitor Bank
Outline
• Project Description
• Theory
• Final Design
• Budget
• Learning Experience
• Conclusion
• Acknowledgements
• Demonstration
Project Description
• Design a safe tabletop railgun to be used for performing experiments in a high school classroom
• Fire lightweight projectiles at low velocity• Design laboratory experiments and/or
classroom lesson plans• Budget : $700• Client: Ms. Anne Marie Johnson, Science
Dept. Chair, Chamblee Magnet School
Railgun Theory•To determine the force that acts on the armature - Lorentz equation
•I = Current •L = length along which current is flowing •B = uniform magnetic field
•To determine the exit velocity of the projectile, we find:
where,
•V = velocity •L' = inductance of rods •I = current •t = time length of current pulse •m = mass of projectile
V L I2t
2m
F e
V B I
L
B
Final Design
• Rails
• Injection System
• Armature
• Capacitors
• Charging System
• Casing
Final Design - Rails
• Requirements– High conductivity– Durable– Low coefficient of friction
• Material Selection: – Silver-Plated Copper 110 AlloySilver-Plated Copper 110 Alloy
• L Shaped to plug directly into capacitor bankL Shaped to plug directly into capacitor bank
Final Design – Injection System
Purpose: Give the armature initial velocity to prevent welding
Final DesignOriginal Design
Old design Spring Based Inconsistent
Final design Compressed Air Powered Remotely activated
Final Design - Armature
• Requirements– Conductive– Low coefficient of friction– Lightweight
• Materials Selection: Aluminum, GraphiteAluminum, Graphite
AluminumAluminum
•high conductivity
•low wear resistance
•lower melting point than rails, armature melts instead of rails
•causes frictional wear
GraphiteGraphite
•low conductivity
•high wear resistance
•higher melting point than rails, rails melt instead of armature
•self lubricating, minimal frictional wear
Final Design - Capacitor
• Requirements– High Capacitance / Energy– Fast Discharge– Maximize current generated
• Selection: Panasonic Computer grade Panasonic Computer grade electrolytic, 9300uF @ 450Velectrolytic, 9300uF @ 450V– Fast discharge– Cost effective– Mechanically sound
Final Design – Charging System
• Uses building power (110V AC)
• Fuses and resistors for safety
Solenoid
Capacitor Bank
RectifierTransformer
Fuse
Railgun
Final Design – Casing and Spacer
• Casing:– Material Selection: PlexiglasPlexiglas
• clear so students can see all parts
• Spacer Material– Material Selection: Oil Filled Nylon 6Oil Filled Nylon 6
• Self lubricating• Resistance to wear• Cheaper than Teflon
Budget
• Current Spending:– Copper Bars: $28– Nylon: $34– Solenoid valve: $54– Capacitors: $200– Misc. Parts for Charging system: $60– Misc. Parts for Injection System: $10– Acrylic: $0 (Donated)– Transformer: $0 (Donated)– Bolts: $0 (Donated)– Compressor: $30– Voltmeter: $30– Misc. mechanical parts: $30– Replacement parts: $100– Advisor Consultation Fees: $124
Budget$700
Total Spent$700
RemainingRemaining$0$0
Learning Experience
• Design is a dynamic process and must be flexible to allow for changes
• Buy the ideal materials based on function as opposed to cheap alternatives
• Machining takes a lot longer and is a lot more complicated than originally assumed
Teamwork!Teamwork!
Conclusion
• Our objective was to build a low-velocity railgun for high school demonstration use
• Unique challenge because most research is concentrated in the area of high velocity railguns
• Still within Budget
Demonstration
Acknowledgements
• Dr. Naresh Thadhani and The High Strain Rate Lab
• Matt McGill