Jetting into the future: MAE program's proficiency with jet engines continues to soar

Tuesday, March 11, 2025

Media Contact: Tanner Holubar | Communications Specialist | 405-744-2065 | tanner.holubar@okstate.edu

Students in the School of Mechanical and Aerospace Engineering in the College of Engineering, Architecture and Technology at Oklahoma State University have advanced their research on turbine engines to the point that it could be a future possibility for seniors to design and build a jet engine as their capstone project.  

Under the tutelage of Dr. Kurt Rouser, students in 2024 were tasked with analyzing and designing a compressor assembly on a small gas turbine engine to supply high-pressure air for an unmanned aircraft.  

The team worked with W9er Engineering, an aviation company that works with experimental aircraft, to develop the compressor for one of the company’s unmanned aircraft. The main objective for students was to display their ability to design the compressor based on the specific needs of the aircraft.  

After analyzing what the aircraft needed in terms of air pressure, mass flow rate and shaft rotational speed, the team discovered that an automotive turbocharger had a compressor that met those needs. The commercial part is heavier than would be necessary for an aircraft, but students were able to showcase that the compressor design generated what was needed for W9er’s aircraft.  

Rouser’s team is now moving into another phase of this research. The team will partner with W9er Engineering again and Astrium, a company founded by retired USAF test pilots that produces unmanned aircraft. Students will work on a project to integrate the compressor design into an aircraft produced by Astrium.  

The team’s first task is to change the gearing of the reduction gearbox on the stock turboprop and then make a flange to allow the compressor to be bolted on.  

The second task will be to mount the engine on a test stand and measure pressures and mass flow rates. Rouser said these tasks must be completed by the end of the spring 2025 semester. 

Rouser said it is being proposed to use a hydrocarbon and pneumatic (pressurized air) system. Parts of the system would be driven by a high-pressure air source, which minimizes power loss when the vehicle transitions from the power required to takeoff to the power for maintaining flight.  

Many vertical takeoff and landing drones are battery-powered, which provides the necessary power for lifting but adds weight when the drone is in the air. Rouser said one concept that has started to emerge is hybrid gas/electric drones.  

This type of drone uses an electric battery for liftoff and a gas motor for endurance in the air, but having two power systems would mean one would become deadweight while not in use. Rouser’s team will look to tackle this challenge.  

“That is the question we are asking from an academic standpoint,” Rouser said. “If you look at the options for vertical takeoff and landing, do you do all gas? Do you go all-electric? Do you go with a hybrid between gas and electric? But a new question we are asking is if you could do it with some sort of pneumatic device. So, with that in mind, the first thing we are just trying to do is figure out if we can even use a turboprop to produce the high-pressure air that we need.” 

The first phase of the project with W9er showed that the students can accomplish the goal by analysis and design. Rouser said by the end of the spring semester it will be known if it can be done in practice. 

Astrium will design the airframe from May to November to house this system. During that time, students will get the results of the system mockup with the automotive turbocharger. Before receiving the frame, the team will work to make custom lightweight parts to avoid taking something off the shelf and modifying it.  

Once this is accomplished, the team will perform tests to ensure the viability of the compressed air source. They will then work to integrate it into the airframe produced by Astrium. This could lead to the project being completed in summer 2026.  

“At that point, any lessons we learned from the process of integrating it to the vehicle will influence any design changes and we will refine things so that by April 2026, we can potentially have the first test flight,” Rouser said.  

Assembling the aircraft will be an incredible opportunity for students. They likely will utilize parts that would not be ideal for an actual aircraft due to the weight, but the experience of putting it together will be an educational one.  

“This is a good learning experience for us,” Rouser said. “Being able to take that idea and get it integrated into a vehicle is going to be a great educational experience.” 

With the continued advancement within the program, more students are getting involved with turbine research. Rouser has involved freshmen, sophomores and juniors with the research projects, allowing them to gain experience as they progress through the program.

MAE students have long successfully designed inlets and nozzle parts for small turbojets. They are becoming more adept with compressors and turbines, leaving the combustor as a primary challenge.  

Zach Wattenbarger, an MAE graduate student, is working on this aspect of the engine research this spring. The combustor is a challenge due to the need to take liquid fuel, vaporize, inject, mix and burn it. 

He has worked on developing a micro-turbojet combustor. Micro-turbojets are generally considered to have a thrust range of 10-500-pound thrust, and Wattenbarger is working to develop a combustor with a 22-pound thrust. This combustor will then be retrofitted to a power turbine with a centrifugal compressor to the turbojet's exhaust to produce high-pressure air. 

Wattenbarger is working on using additive manufacturing to make a better fuel manifold to help distribute and vaporize the fuel. Rouser said this represents one of the last hurdles students face when designing and building a jet engine.  

Other challenges lie in the subsystems, such as the bearings, fuel pump, starter, igniter sensors to measure rotations per minute and exhaust gas temperature.  

Wattenbarger and other students have worked to develop a custom engine control unit that functions along with the subsystems to monitor and control the engine from start-up to full throttle. 

Trending toward commercialization 

Through AFWERX, the innovation arm of the U.S. Air Force, MAE students could potentially get to the point of commercializing the engines they design. AFWERX looks to take technology that can be developed quickly into an asset for the USAF to put into the field.  

The design would be purposely geared toward the specific needs of the aircraft designed.  

“Presuming all of that works well, the Air Force basically would have an option to go ahead and start placing orders,” Rouser said. “This would have to be built specifically for this particular design. The novel part of this is the propulsion system that W9er is bringing to the table. If each of us is successful in our part of the project, then the Air Force, through AFWERX, could quickly turn this into a fielded asset.” 

Rouser said Jetilus Aero, LLC, established in 2023 in collaboration with Cowboy Technologies and other OSU entities, to help with the potential commercialization of technology Rouser’s team develops. 

Two National Science Foundation I-Corps teams have also been formed by students. They will participate in a program that gives students the experience of taking an idea and exploring its commercial potential.  

Students will talk to potential customers and industry stakeholders, working to identify any problems the customer needs to solve.  

“The goal for one of the teams is to develop what we call micro-turbojet,” Rouser said. “They've proposed to take that idea and start exploring the commercial potential.” 

Building a jet engine as a capstone project 

One of the current capstone projects for MAE students is participation in the Aerospace Propulsion and Outreach Program, an annual collegiate competition sponsored by the Air Force Research Laboratory in which seniors design and modify gas turbine engines. 

A goal on the horizon is for Rouser’s senior students to be able to design a jet engine as their capstone project.  

Part of this potential is having more students involved with turbine research. With their first exposure to engine research, they aren’t expected to be experts, but they can gain valuable experience they can build on as they progress through the MAE program.  

“I need to start preparing the pipeline of talent right now, starting with freshmen, so that a freshman is getting exposure to this,” Rouser said. “They are getting exposed to seniors who are working on this. And as sophomores and juniors, they are getting more experience with it and becoming more adept at it.” 

Key elements of designing a turbojet engine are the facility resources and necessary equipment, such as a metal 3D printer and high-speed dynamic balancer, which would be a challenge to fund yearly. It is also imperative that students can develop the technology.  

Rouser said things are starting to come together to the point where it is creating a new era for propulsion studies in CEAT.

“My dream vision at the end of this is that we are so good at this that we turn it into an undergraduate capstone design project that we run every year. We could take undergraduate seniors and say, ‘I want you to design a turbine engine, maybe a turbojet that can produce a certain amount of thrust.’”