Sparrow Design Review

DARE's new flagship project Sparrow is in the final stages of the detailed design of its liquid-fuelled rocket engine. Right before the Christmas break, they hosted a design review for the combustion chamber, cooling and the feed subsystem.

Having worked online for the last half a year, engineers of Project Sparrow presented the outcome of the DLX150 Firebolt engine design to the rest of the members of DARE and distinguished guests from APP and the TU Delft Aerospace Faculty on 10th December, 2020. This review was meant for design decisions to be criticised  before the final decisions can be made and parts can be ordered. 

The review started with management presenting updates on acquisitions and the overall timeline of the project. The project is currently  on track both in terms of sponsorship and timeline, despite the ongoing pandemic putting a sizeable spoke in the wheels. Regardless, the team is now ordering parts for the tanks and the engine, and is awaiting the end of lockdown to start the production. 

The review followed with a presentation of the Combustion Chamber and Cooling team design. The engine will have 15 kN thrust at 50 bar chamber pressure, utilising 90% ethanol and liquid oxygen for its 40 second combustion. Its thrust chamber will be made of Inconel IN718, which allows for 3D printed manufacturing and acceptable thermal stresses. Of course, such material would still have to be cooled during firing of the engine, hence the team is going for the regeneratively cooled design. The fuel will reach the chamber through a pintle injector with a copper tip and stainless steel faceplate. Finally, following DARE traditions, the igniter is made of steel wool surrounding a small charge of gunpowder, allowing for a quick and reliable ignition. 

Afterwards, the design of the feed system was presented. The system valve architecture is based on previous work done by the Cryogenic Propulsion team, having replaced a few solenoid valves with pneumatic ones to allow for larger pressures. Unusually, the team decided to go for 4 tank setup for the test fire due to acquisitions and size limitations. As such, 4 aluminium-6082 tanks, together fitting 150 litres of Liquid Oxygen and 132 litres of ethanol, will now be produced, able to withstand 65 and 84 bar pressure respectively.  The system will be pressurised with 7 gaseous nitrogen bottles, allowing for constant pressure throughout the burn time of the engine. The question round followed, focusing on the ways to fill the tanks (Ethanol will be filled manually through a funnel at the top of the tank, while LOX will be filled from the bottom, opening the fill valve remotely), as well as overall safety concerns. Nevertheless, the team will still be having a safety review clearing the path for further work.

In March, another Design Review will be held for the Thrust Vector Control and Electronics teams. Stay tuned to hear more about Firebolt and Project Sparrow here and on our social media!


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