Mechanical Engineering Rowan University 201 Mullica Hill Rd. Glassboro, NJ 08028

1. 36th Annual Frontiers in Education Conference San Diego, CA, Oct. 28-31, 2006 THIS IS ROCKET SCIENCE: DEVELOPMENT AND TESTING OF A HYBRID ROCKET MOTOR IN A ROCKET PROPULSION COURSE Anthony J. Marchese Mechanical Engineering Rowan University 201 Mullica Hill Rd. Glassboro, NJ 08028 http://users.rowan.edu/~marchese

2. Overview This is Rocket Science: The Hybrid Rocket Motor Project • Motivation for a project based learning experience in rocket propulsion • Context: Description of the rocket propulsion course • Description of the project: objectives, requirements and constraints • Development of the analytical model • Design and fabrication of the hardware • Development of the hybrid rocket motor test stand • The Engineering Clinic • Test results • On going tests

3. Course Objectives Introduction to Rocket Propulsion (ME 412) Rocket propulsion draws upon the fundamental concepts of thermodynamics, chemistry, fluid mechanics and heat transfer to design propulsion systems. At the conclusion of the course, each student will be able to: • Analyze the performance of an ideal rocket engine. • Select propellants and choose a rocket propulsion system based on mission requirements. • Perform thermochemical calculations to determine the rocket chamber temperature and chemical composition for any propellant combination. • Design a liquid propellant rocket engine by considering the propellant combination, combustion chamber, injector, igniter, nozzle, heat transfer and cooling characteristics. • Design a solid propellant rocket motor based on the propellant combination, burning rate laws and grain design. • Design a hybrid rocket motor based on the propellant combination, burning rate laws and grain design. • Build and test a 10 lbf thrust hybrid rocket motor.   Measure specific impulse, characteristic exhaust velocity, thrust coefficient and compare to theoretical calculations.

4. Motivation for the Hybrid Rocket Motor Project Private Sector Opportunities in Space Exploration On October 4, 2004, SpaceShipOne became the first private manned spacecraft to exceed an altitude of 328,000 feet twice within a 2 week period, thereby claiming the $10 million Ansari X-Prize. SpaceShipOne was powered by a hybrid rocket motor (liquid N2O, solid polymer fuel) N2O solid fuel

5. The Hybrid Rocket Motor Design Project Objectives, Design Parameters and Constraints Objectives of the semester design project: • Design, build and test a hybrid rocket motor. • Develop a theoretical model that predicts the performance of the hybrid rocket motor as a function of time. • Compare measured performance with theoretical model. Constraints: • Oxidizer must be gaseous oxygen (GOX) • Maximum Chamber Pressure: 115 psia, Ambient Pressure: 14.7 psia • Maximum GOX flow rate: 500 SLPM • Minimum initial thrust: 5 lbf • Fuel grain outer diameter = 1.175 in • Maximum Fuel Grain Length = 12 in • Fuel: HTPB, HTPB/AL, PMMA, PE, UHMW or paraffin

6. Ab Liquid oxidizer Ap Pc Ae solid fuel At Tc, Xi, g Characteristic Exhaust Velocity Specific Heat Ratio Hybrid Rocket Motor Design Project Theoretical Model: This is Rocket Science Fuel Regression Rate Thrust Coefficient Fuel Mass Flow Rate Thrust Specific Impulse Chamber Pressure

7. The NASA CEA Chemical Equilibrium computer code was used to calculate Tc, g, MW, C* and Xi as a function of oxidizer to fuel ratio. fuel + oxidizer products + energy Hybrid Rocket Motors Thermochemical Model: This is Rocket Science

8. Hybrid Rocket Motor Design Project Theoretical Model Results The detailed analytical model was used to predict the variation in fuel flow rate, O/F ratio, chamber pressure, thrust and specific impulse (Isp) with time.

9. The Hybrid Rocket Motor Design Project Concept Design and Parametric Design The theoretical hybrid rocket motor model was also used iteratively optimize their final design to choose the following parameters: • fuel grain length • port diameter • throat diameter • nozzle area ratio • nozzle exit diameter L de dt dp Final design drawings were generated for the combustion chamber and the supersonic nozzle using Solid Works.

10. Combustion chambers were fabricated from aluminum round stock using manual lathes Supersonic nozzles were fabricated from graphite using a CNC turning center The Hybrid Rocket Motor Design Project Fabrication

11. Hydroxyl Terminated Polybutadiene (HTPB) was formulated, mixed with aluminum particles and cured. Other fuels such as PMMA, HDPE and UHMW were machined from solid round stock The Hybrid Rocket Motor Design Project Fuel Formulation

12. The Hybrid Rocket Motor Design Project Development of the Hybrid Rocket Motor Test Stand Mass flow rate was measured and controlled using a Teledyne Hastings HFC203 Mass Flow Controller. Thrust was measured using an Omega LC101-25 load cell. Chamber pressure was measured using an Omega Pressure Transducer. The Objective: Deliver a hybrid rocket motor test stand capable of measuring thrust (0-10 lb), chamber pressure (0-250 psig), oxygen mass flow rate (0-500 SLPM) The Team: Two senior mechanical engineering students, one junior mechanical engineering student and one senior electrical engineering student. The ignition system consists of dual automotive spark plugs which are energized using an ETP 300ST solid state induction coil

13. The Hybrid Rocket Motor Design Project Development of the Hybrid Rocket Motor Test Stand Solenoid Valve Flow Controller Igniters Pressure Transducer Check Valve

14. The Hybrid Rocket Motor Design Project Development of the Hybrid Rocket Motor Test Stand Load Cell Linear Bearing

15. The Hybrid Rocket Motor Design Project Data Acquisition Data acquired included: instantaneous chamber pressure, thrust, oxygen mass flow rate and high speed dynamic chamber pressure The data were acquired using an Agilent 34970A Data Acquisition Unit with GPIB interface and an HP 54645D digital storage oscilloscope With these data, each team was able to measure specific impulse (Isp), characteristic exhaust velocity (C*) and thrust coefficient (CF) and compare these measurements to their analytical models.

16. The Hybrid Rocket Motor Design Project Test Firing (HTPB/20% AL/GOX)

17. The Hybrid Rocket Motor Design Project Test Firing (Big Red)

18. The Hybrid Rocket Motor Design Project Experimental Results The analytical models reproduced the experimental data reasonably well. When the variation in actual oxygen mass flow rate was taken into account, analytical results matched the experiments very well!

19. The Hybrid Rocket Motor Design Project Ongoing Work The system is now being used for a research project on the effect of fuel type on combustion instability of hybrid rocket motors.

20. The Hybrid Rocket Motor Design Project Conclusions • At the beginning of the semester, students showed very little awareness of the space program and its significance (both historic and contemporary). • This condition is surprising to the generation who grew up wanting to be astronauts. • The hybrid rocket design project was successful in introducing a new generation of students to rocket science. • The hybrid rocket motors were inexpensive, relatively easy to build and safe. • The hybrid rocket motor test stand was an effective junior/senior level design project. Total project cost was approximately $2000. • The test stand is now being used for scholarly pursuits.

21. The Hybrid Rocket Motor Design Project Is this valve open?