We Decided to Go with a Propulsion System for the 1 Kg Payload Consisting of a Hybrid First

4.2.4.1 1 kg Propulsion 1

The propellants we selected for the 1 kilogram payload launch vehicle were a hybrid first stage and a solid second and third stage. Our selection process involved the use of an optimization code which gave us the best results for a 1 kilogram payload launch vehicle. The code gave us a propulsion system described in the following section.

Our launch vehicles first stage consists of a hybrid fuel rocket motor. This fuel consists of hydrogen peroxide as the oxidizer and hydroxyl terminated polybutadiene (HTPB) as the solid propellant. The hydrogen peroxide is first catalyzed and then fed through the grain of the solid fuel where it combusts and travels through the nozzle. The nozzle is a 12° conical nozzle with LITVC attached. The LITVC system is composed of four valves that allow H2O2 to be injected into the nozzle at a 90º angle to the centerline of the nozzle. A schematic of the LITVC can be seen below in Figure 4.2.4.1.1.

Figure 4.2.4.1.1: LITVC and Nozzle Configuration

In Figure 4.2.4.1.1, the nozzle is shaded grey and all LITVC components are highlighted in orange. The pipes are run from the H2O2 tank that is used for the hybrid motor, and then is distributed to each valve. The valves are connected to the controller which relays a signal for a certain valve to open and allow pressurized H2O2 to be injected into the main flow in the nozzle, which produces a side thrust. This side thrust allows for control

Author: Ricky Hinton, Stephan Shurn 4.2.4.1 1 kg Propulsion 1 of the launch vehicle during its ascent. There is only one engine for this stage. The specific values for the first stage can be seen below in Table 4.2.4.1.1.

Table 4.2.4.1.1 1 kg Payload Stage 1 Propulsion Specifics Variable Value Units Vacuum Specific Impulse 352.3 s Chamber Pressure 2,068,000 Pa Mass Flow Rate 6.730 kg/s Propellant Mass 947.9 kg Engine Mass 72.62 kg Thrust (vac) 21,435.5 N Burn Time 140.8 s Exit Area 0.342 m2 Exit Pressure 2,821.167 Pa

A conical nozzle was chosen because of the solid particles of propellant that will be coming out of the combustion chamber. The combustion process does not necessarily combust the fuel 100% and these particles can deteriorate a nozzle if it is let’s say Bell shaped. Some of our early MAT codes had values based off of a 12° conical nozzle and that is one of the reasons we decided on this cone angle for the final design. Also having a smaller cone angle reduces the divergence loss at the exit of the nozzle. A picture of the nozzle can be seen below in Fig. 4.2.4.1.2.

Author: Ricky Hinton, Stephan Shurn 4.2.4.1 1 kg Propulsion 1

Figure 4.2.4.1.2: Our 12° conical nozzle

For our second stage we chose a solid rocket propellant. The compound for this propellant is Hydroxyl-terminated Polybutadiene/ Ammonium Perchlorate/ Aluminum (HTPB/AP/AL). The nozzle once again is a 12° conical nozzle due to the solid propellant. The LITVC system is attached to the nozzle. The LITVC has the same configuration as the first stage, with the exception of the H2O2. Since there is no H2O2 already present due to the solid motor, a pressurized tank is added in a curved configuration sitting beneath the solid motor. The tank wraps around the nozzle and is pressurized with gaseous nitrogen so that the H2O2 can flow into the lines for injection. There is again only one engine for this stage. Table 4.2.4.1.2 below shows the specifics for this stage. Table 4.2.4.1.2 1 kg Payload Stage 2 Propulsion Specifics Variable Value Units Vacuum Specific Impulse 309.3 s Chamber Pressure 6,000,000 Pa Mass Flow Rate 1.880 kg/s Propellant Mass 336.92 kg Engine Mass 36.44 kg Thrust (vac) 6,052.4 N Burn Time 179.2 s Exit Area 0.028 m2 Exit Pressure 11,453.660 Pa

Author: Ricky Hinton, Stephan Shurn 4.2.4.1 1 kg Propulsion 1

The third and final stage for this launch vehicle consists of a solid propellant motor. The propellant for this stage once again is Hydroxyl-terminated Polybutadiene/ Ammonium Perchlorate/ Aluminum (HTPB/AP/AL). The nozzle is once again a 12° conical nozzle but does not have LITVC control for this stage. There is a single engine for stage three. The specifics can be seen in Table 4.2.4.1.3 below for stage three of this one kilogram launch vehicle.

Table 4.2.4.1.2 1 kg Payload Stage 3 Propulsion Specifics Variable Value Units Vacuum Specific Impulse 309.3 s Chamber Pressure 6,000,000 Pa Mass Flow Rate 0.231 kg/s Propellant Mass 45.09 kg Engine Mass 9.53 kg Thrust (vac) 743.4 N Burn Time 195.3 s Exit Area 0.003 m2 Exit Pressure 11,453.660 Pa

Author: Ricky Hinton, Stephan Shurn