1. Rockets AND Composites Design and Fabrication MIT Rocket Team November 20, 2010

2. An Introduction to COMPOSITES

3. 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

4. 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

5. 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

6. Body Tube Ply Layup • Determine number of plies • Meet loading requirements • Manufacturing reasons • Additional plies at bulkheads and ends • Antisymmetic and Axisymmetric

7. Your Mission

8. 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”

9. [Build Composites]

10. Rocket Basics An Introduction to ROCKETS

23. Rocket Equation • Initial Mass • Propellant • Structural Mass Fraction • Payload • Delta-V to Earth orbit: ~10 km/s

26. Composites Design

27. 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

28. Why Composites?

29. Z T L Evaluation of Composites • Standard Laminates • Rule of Mixtures • ETc = vfETf + vmETm • Stiffness is simply the average of stiffnesses • Be sure to account for direction Z Matrix Fiber T L graphite/epoxy

30. Sandwich Materials

31. Composites Fabrication Techniques (Cont)

32. 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

33. 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

34. 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

35. Composites Fabrication Examples

36. Fins

37. Body Tube

38. Nose Cone

39. Completed

40. SpaceX Interstage Mandrel

41. Composite Testing

42. Instron Testing

43. Prep

44. Load Testing

45. Engine Testing

46. Pyro Test

47. On the Launch Rail

48. Launch

49. Merlin Engine

50. Engine Fires