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MIT Rocket Team November 20, 2010 Design and Fabrication.
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Transcript of MIT Rocket Team November 20, 2010 Design and Fabrication.
MIT Rocket TeamNovember 20, 2010
Design and Fabrication
An Introduction to COMPOSITES
Carbon Fiber Carbon fiber custom laminate Material: 5.7 oz 3k twill carbon fiber
sheet Epoxy
Aeropoxy 2032 resin Aeropoxy 3665 hardener
Aspects High strength-to-
weight ratio High cost
Fiberglass
Carbon fiber is RF opaque Material: 6 oz plain weave fiberglass Epoxy
Aeropoxy 2032 resin Aeropoxy 3665 hardener
Locations Fairing Potentially second
stage body or sections
General Fabrication Techniques Elevated temperature cure
Custom-built oven Inner dimensions sufficient for full
cure of either stage Capable of reaching in excess of
300º F Not necessary for epoxy choice, but
provides additional temperature resistance
Reduces cure time Improves resin distribution and
mechanical properties
Vacuum bagging Improves surface
finish of part Reduces weight
before removal of excess epoxy
Body Tube Ply Layup Determine number of plies
Meet loading requirements Manufacturing reasons
Additional plies at bulkheads and ends Antisymmetic and Axisymmetric
Your Mission
Fin Design Sandwich laminate
Balsa core (1/8”) Single–layer carbon fiber facesheets
Construction Cut balsa to shape Cut vacuum bagging materials Apply thin film of epoxy to balsa Apply facesheets Apply additional epoxy and ensure is well
distributed Apply vacuum bag release, then breather, then
strechlon Insert vacuum tube and cover edges with sealant
tape Fin Sizing
Semispan: 5” Chord: 5”-3”
[Build Composites]
Rocket BasicsAn Introduction to ROCKETS
Rocket Equation
Initial Mass Propellant Structural Mass Fraction Payload
Delta-V to Earth orbit: ~10 km/s
Propulsion Type Isp
Solid 250
LO2+LH2 450
LO2+RP-1 350
Electric 2000
Composites Design
What are composites?
Single Ply Carbon or glass fibers Epoxy matrix Usually unidirectional, but can be weave
Laminate Multiple plies
Sandwich Face sheets of plies Spacer material between
Why Composites?
Evaluation of Composites
Standard Laminates Rule of Mixtures E T c = v fE T f + v mE T m
Stiffness is simply the average of stiffnesses Be sure to account for direction
Z
T
Lgraphite/epoxy
Matrix
Fiber
Z
T
L
Sandwich Materials
Composites Fabrication
Techniques (Cont)
Body Tube Manufacturing
Prepare mandrel of phenolic tube with wax, mylar
Apply resin Apply fabric and work in resin Repeat for all plies Remove excess Apply vacuum bag material Bake for 1 hour Remove from mandrel Cut then sand edges
Bulkhead Design
Purpose: attach motor casings to airframe Design Options
Plastic rings Holes included around periphery for wiring and
antenna Inner portion secured with tape friction fit Outer portion secured with epoxy from both sides
COTS casings
Validation Static pull motor simulation Static fire testing
Fairing Design Material: Fiberglass Design Options
Tangent ogive: easy to build Von Karman: drag for large mach range Parabola: drag at subsonic speeds
Construction Layup in halves on aluminum mandrel and
plate Cure halves Affix together with strips Cure again Sand until smooth Apply additional filler as necessary
Composites Fabrication Examples
Fins
Body Tube
Nose Cone
Completed
SpaceX Interstage Mandrel
Composite Testing
Instron Testing
Prep
Load Testing
Engine Testing
Pyro Test
On the Launch Rail
Launch
Merlin Engine
Engine Fires
Static Fires
Questions?