Integrated Rocket Ramjet

Mach 4 Logo
Sponsors	Dr. John Crepeau University of Idaho Department of Mechanical Engineering
Team Name	Mach 4
Duration	Fall 2015 - Spring 2016
Faculty Advisers	Dr. Michael Maughan
Mentor	Jacob Gilles
Students	Alexx Jensen Christopher Fraser Jesse Caudle Marc Compton

Design and model an integrated rocket ramjet. The engine transitions without sacrificial parts from the rocket to the ramjet stage upon reaching the design speed. Key features include a sealing inlet and a liquid fuel ignition source that doubles as a barrier to shield components from the solid rocket propellant.

Problem Definition

Background

A ramjet is a type of engine used for supersonic flight. It operates at speeds around Mach 3 but cannot function at speeds much lower than Mach 1.5. Because of this, ramjet engines are typically brought to an ideal speed before activating. Currently this is done in two ways; first being by a booster rocket that detaches after usage, and second by carrying the ramjet engine on a jet plane and dropping it when the engine ignites. The goal for this project is to develop a third way for ramjet flight, utilizing a solid rocket combustion chamber and a nosecone that can function as an inlet at high speeds.

Deliverables

The deliverables for this project include; a detailed design for an adjustable nosecone and diaphragm that utilizes aerodynamics, a quarter cut out model showing the functionality of the integrated ramjet, and a basic model of the rocket that can be used for simplified testing of the nosecone, diaphragm, and other assemblies/components.

Specifications

Client Specifications

Project Learning

Most of the project learning for the integrated rocket ramjet revolved around ramjets and their functionality, as well as solid rockets and how to design them. For this design, in order to get the ramjet to speed a solid rocket will be attached to the ramjet engine. Once the propellant is burned, the rocket will function as the combustion chamber for the ramjet. To make this design possible, research had to be done on both rocket propellants and ramjet engines.

The image on the left below shows different grain geometries for solid rocket propellant. This was useful because it helped us decide which geometry would give us the best thrust pattern to obtain the proper transition speed. We ultimately decided to go with #2, this option provided the rocket with consistent thrust which allows for easier calculations and design.

Along with propellant research we found information on the functionality of the ramjet. Below on the right is a basic image on how a ramjet operates. Using this information we were able to brainstorm ideas on how to create a moving nosecone and where to store the liquid fuel for the ramjet part of flight. We found the best place to store the liquid fuel would be in the extra space by the diffuser (the yellow section of the image).

Rocket Grain Designs

File:2015 Ramjet diagram 1024 C.jpeg Rocket Grain Designs

Concept and Design

To get the Ramjet to its ideal flight path, solid rocket propellant is stored in the ramjet’s combustion chamber and functions initially as a rocket booster. During this stage the nose cone to the ramjet engine will remain shut and a diaphragm will be in place to block any solid propellant from getting into the rest of the engine (this can be seen in the first image below).

Once the solid propellant is burnt, the nose cone and diaphragm open up allowing the ramjet to begin operation. This part of the design is important because it allows for the whole body to become the ramjet, and does not require the rocket portion to drop off. Instead the space where the solid rocket propellant was stored is now the combustion chamber for the ramjet. The ramjet then takes over for the rest of the flight, operating at its design conditions (this can be seen in the second image below).

Rocket Stage

Ramjet Stage

Assembly

Nosecone Design

In order to open and close the nosecone between rocket and ramjet flight, a screw mechanism has been developed to close the gap. This system uses a screw and a motor to push the front of the nosecone against the cowling to create an air tight seal, ideal for the rocket portion of flight. Once the rocket stage is complete the screw will spin within the motor pulling the front section of the nosecone back along guides. Now the inlet will be ideal for the ramjet section of flight.

Closed Nosecone

Diaphragm Design

The second crucial component to the integrated rocket ramjet is the opening diaphragm which will take place during the transition to ramjet operations. The diaphragm consists of three bars to support a hinge, three bars to support the ends of the flaps, and the flaps that will open and close themselves. The flaps will remain closed due to the physical pressure of the solid fuel as well as the pressure created when the propellant is burning. Once the solid fuel is completely burnt the air from the moving nosecone will force the flaps open. This transforms the area where the solid rocket fuel was into a combustion chamber.

Closed Nosecone

Machining the Final Product

To properly show the functionality and ingenuity of our design, we have developed a working 3D computer model and a quarter cutout machined model of the integrated rocket ramjet. Below images can be seen of each of the main components as they are being machined and their final product.

Nozzle:

Nozzle being Machined

Nozzle Completed

Nose Cone:

Back Nose Cone

Front Nose Cone

Cowling:

Cowling being Machined

Cowling Completed

Rear Diffuser:

Rear Diffuser being Machined

Rear Diffuser Completed

Full Assembly and Display

Here the total Rocket Model can be seen. This assembly includes a quarter cutout view in order to show individual components, and highlights both the barrier and adjustable nose cone designs. Below the rocket can be seen at a booth display accompanied by a poster to explain project details.

Total Model Assembly

Display Booth

Team Information

	Alexx Jensen	Career Goals: Follow a career in the Automotive Industry and/or pursue it as a hobby To obtain Professional Engineer Certification Leave where ever I work a better place than when I entered
	Mechanical Engineering Undergraduate
	Hometown: Idaho Falls, Idaho
	Email: jens4061@vandals.uidaho.edu
	Christopher Fraser	Career Goals: To obtain a Masters Degree in Aeronautical Engineering Work for a small aircraft design company To build a personal aircraft from the ground up
	Mechanical Engineering Undergraduate
	Hometown: Coeur d'Alene, Idaho
	Email: fras0348@vandals.uidaho.edu
	Jesse Caudle	Career Goals: To obtain Professional Engineer Certification To dually pursue further education while in the workforce Move towards a path in engineering project management
	Mechanical Engineering Undergraduate
	Hometown: Idaho Falls, Idaho
	Email: caud8300@vandals.uidaho.edu
	Marc Compton	Career Goals: To obtain a professional engineer certification Pursue a career in sustainable energy and engineering practices Save the World
	Mechanical Engineering Undergraduate
	Hometown: Boise, Idaho
	Email: comp8033@vandals.uidaho.edu

Document Archive

All Meeting Minutes