Booster Nozzle Cross-Section Booster Nozzle Exploded View
Overview
The Booster Nozzle Assembly is intended to be used on Pheonix 1, attached to the booster stage of the rocket. It is made up of four components: the nozzle carrier, phenolic insert, graphite insert, and phenolic cap. After manufacturing these parts will be sealed together using high-temp silicone RTV sealant. The entire assembly will then be bolted to the back end of the motor case using 24 1/4-20 Bolts. The nozzle is sealed to the case using two O-rings, one primary and one redundant, on the outside of the aluminum nozzle carrier. The purpose of these O-rings is to keep the hot gases from combustion inside the chamber and prevent exhaust leakage and therefore an inefficient and possibly dangerous burn. To select the right size O-ring gland size, we used the calculator at this link: https://www.applerubber.com/oring-gland-calculator/#medium-search-field.
Design:
Nozzle Basic Dimensions:
Throat Diameter: 1.085 in
Exit Diameter: 3 in
Throat Length: 0.1 in
Convergent Angle: 60 degrees
Divergent Angle: 15 Degrees
Parts:
| Part Name | Material | Purpose | Manufacturing Equipment |
|---|---|---|---|
| Graphite Insert | Graphite | The graphite has a high melting point, and is able to absorb most of the heat from combustion, and forms the throat of the nozzle. | Lathe |
| Phenolic Insert | PE Phenolic | Phenolic in the nozzle acts as a mediator for conductivity between the graphite and aluminum since graphite is extremely conductive. The phenolic insert also forms the first part of the divergent section, which allows the exhaust to expand to match the ambient pressure. | Lathe |
| Phenolic Cap | PE Phenolic | Forms the convergence section of the nozzle, which compresses the exhaust and accelerates it to supersonic speeds and therefore producing more thrust. | Lathe |
| Nozzle Carrier | Aluminum 6061 | Houses the other three parts, and is the bolt connection point to the motor case and the rest of the rocket. It also forms the back half of the divergent section, bringing the expansion ratio up to make sure the exit pressure matches ambient pressure | Lathe; Radial Indexer on Mill |
Manufacturing Tips:
General Tips:
- Before anything else is turned, face your piece of stock so that the front face is directly perpendicular to the rotational axis on the lathe.
- Turn the stock piece down to the largest diameter present on the part first before making other features on the part.
- Make sure to set your tool settings to "fine control when contacting part, unless only taking off a small amount of material
- When turning on the lathe, the best results will come from turning at a constant rate, not a slow rate.
- Be aware of the surfaces that will interface with other parts, these will require the most precision.
- when all parts are complete, make sure to fit check them before gluing them together.
Graphite Insert:
- Critical Feature: throat ID (double-check this measurement when manufacturing)
- Graphite is easy to turn, but horrible to clean up. Make sure to use the vacuum to avoid breathing in particles (may want to wear a mask)
- When cutting out the center, use the boring tool to create the hole and then use the finishing tool to expand the hole to the correct size.
Phenolic Cap and Insert:
- Phenolic creates extremely small shavings, you must use a vacuum to turn phenolic on the lathe, the debris could make tolerancing more difficult.
- Use a long arm part tool to reach inside the phenolic insert.
Nozzle Carrier:
- Aluminum must be cut slow.
- turn all the features of the nozzle carrier before using the radial indexer on the mill
- Use the square-shaped tool bit to cut the O-ring grooves.