Project Sparrow
BURN
BRIGHTER
WITH
SPARROW
Project Sparrow was DARE’s flagship project from 2020 to 2022. Building on the knowledge gained by the now retired Cryogenics team, Project Sparrow aimed to:
"Design, build, and test a thrust-vectoring, liquid fuel rocket engine"
Project Sparrow began with the goal of developing an engine that could power the next generation of high-performance rockets and propel DARE’s efforts towards building rockets that aim for the 100 km Karman line and eventually enable the organization to become the first student-led group to send a rocket into orbit around Earth. The developed engine DLX 150B ‘Firebolt’ is used on DARE’s new flagship project Stratos V.
Engine
DLX 150B 'Firebolt'
The DLX 150B ‘Firebolt’ engine is the second generation of Firebolt, sucessing the DLX 150A engine. Firebolt uses ethanol and liquid oxygen as rocket propellants and is DARE’s first ever liquid fuelled engine.
Propellant LOX/EtOH
Thrust 15kN/3400 lbs
Origins of Sparrow
Project Sparrow was built on the legacy of the now-retired Cryogenics Team of DARE, which came up with the idea to build a liquid-propellant engine in the summer of 2020. A major difference between Project Sparrow and the previous flagship projects in DARE is that the previous projects – the Stratos projects, which have been a mainstay of DARE for many years – have always involved building a full rocket, while Sparrow was focused solely on developing an engine.
The project began in the summer of 2020 with a team of 17 full-time members, with an additional 21 part-time members joining at the start of the academic year.
One of the unique challenges faced by Project Sparrow is that it was DARE’s first full-time project to be dealing with the Covid-19 virus from the start. This has resulted in the project being almost fully online, with team members relying heavily on digital communication and collaboration tools to stay connected and make progress.
As DARE looks to the future, the organization is excited to continue blazing the trail for the next 20 years of students in space and Project Sparrow was an important step in that journey.
In the future the knowledge gained during this project will enable DARE to go orbital, with engines based on the lessons that were learned from Project Sparrow.
A Detailed Examination of the 'Firebolt' Engine
Testing is completed! DLX 150A and DLX 150B engine combined were tested in nine hot-fire test campaigns and reached a burn time of over 30 seconds at full flow. The engine ran at a chamber pressure of 30 to 50 bar and achieved average thrusts 9 to 11 kn.
This is the DLX-150B Firebolt, DARE’s first liquid-fuelled engine. Burning 6.2 kilograms of liquid oxygen and ethanol per second and producing 15 kN of thrust. The engine is regeneratively cooled, with the ethanol flowing through 84 cooling channels in the chamber. These channels are built around the chamber walls. Normally this leads to a complex manufacturing process, but the DLX-150B is 3D printed from Inconel 718, by Sparrow’s main sponsor, Materialise. Due to the engine’s small size the throat will experience such extreme heat that additional cooling is required. This is accomplished using film cooling, where a fraction of the ethanol from the cooling channels is injected directly into the chamber. There, it forms a thin cold layer, protecting the nozzle walls from the extreme heat.
DLX-150B Engine, showing the 3D printed nozzle.
Propellant and pressurant tanks
The engine operates at a chamber pressure of 50 bar. For the propellant to flow into the chamber it must have a pressure higher than it. To do this, the oxidizer and fuel tanks are pressurized, using Nitrogen gas, to 65 bar and 84 bar respectively.
In the picture on the left, all the tanks in the system can be seen. The leftmost tank is the ethanol tank, and the ice-covered tank on the right is the LOX tank, in the process of chilling. The nitrogen used to pressurize the tanks is supplied by the big bundle in the middle.
As the air density is low at high altitudes, aerodynamic control surfaces are no longer effective. Therefore, different means of control are required. Thrust vector control allows a rocket to control its attitude with its engine, instead of only with control surfaces. The DLX-150 engine will be DARE’s first thrust vector controlled engine. This will be achieved by gimbaling the entire engine using two linear actuators, changing the direction of thrust, which, itself, will make the rocket turn.
In the image on the right, the DLX-150B engine can be seen assembled into its test configuration.
TVC system with DLX-150B engine
Hot Fire Tests
6 Videos
TVC Gimbal mounted in a press for validation
The image on the left shows the TVC gimbal, just before it was tested to destruction. This was done to make sure that it is strong enough to survive the thrust of a running engine. While the gimbal ring was destroyed in this test, it failed well above the required load, meaning that the design passed the test.
The thrust bench is the structure to which the engine is mounted for testing. It is equipped with load cells to measure thrust. As testing a rocket engine requires a safe and controlled environment, testing takes place in a test cell at a military facility in the Netherlands. This facility is typically used to test the jet engines used by Royal Netherlands Air Force.
Test Setup with DLX-150A engine mounted onto the thrust bench.
