Spectre - University of Hertfordshire's first liquid bipropellant rocket engine

About UH Rocketry

UH Rocketry is the student rocketry team at the University of Hertfordshire, now in our third year of activity, with around 50 active members across aerospace, automotive, mechanical and electronics engineering. Our team spans foundation through to master's level, and we run several parallel projects each year, including the UKSEDS NRC 12th edition, Mach-26, and an international collaboration with Space Division UEM building a launch vehicle that will carry an SRAD solid motor on its maiden flight in Spain. Spectre is our entry to Race2Space (R2S) 2026, the UK's national university liquid-propulsion competition, with a hot-fire test booked for 24 June 2026 at the Airborne Engineering Ltd (AEL) test facility in Westcott.

The Race2Space competition

R2S is held at Westcott Space Cluster in Buckinghamshire, organised in partnership with AEL and gives student teams access to a professional test stand with feed lines, propellants, and on-site engineers, which is a level of facility students would not otherwise have access to. R2S has expanded from 10 teams at its inception in 2023 to 64 applicants for 2026, reflecting the growing momentum behind UK university rocketry.

Building on Fenton

Spectre builds directly on Fenton, a nitrous/IPA bipropellant engine with an aluminium regeneratively cooled chamber and pintle injector, hot-fired last year. Fenton was built independently during sixth form by one of our members, who joined UH Rocketry this academic year and now leads Spectre's technical work, including the chamber CAD and the pintle sizing code. The thermal data and lessons learned from Fenton's hot fires directly inform our approach to Spectre's regen channel layout, injector geometry, and pintle sizing.

The step up from Fenton to Spectre is substantial as transitioning from nitrous-oxide to cryogenic LOX requires a tighter cleanliness regime, much higher peak heat flux, and a step-up in thrust. The team is committing to the full LOX-class build rather than repeating the nitrous architecture. Fenton's foundation is part of what makes that commitment realistic.

Spectre - Engine Architecture

Spectre is a 6 kN LOX/IPA bipropellant engine running at 25 bar chamber pressure, with a target burn time of 8 seconds at the maximum operating point.

The key design features:

• Slotted copper pintle injector: chosen for atomisation quality and shear-mixing performance
• Dual-pass 30° helical regenerative cooling: IPA coolant routes through 27 downward channels and 27 counter-rotating upward channels, integral to the chamber print
• 18% film cooling: auxiliary chamber wall cooling via 30 radial 0.5 mm holes
• AlSi10Mg SLM chamber: combined with a 6082-T6 CNC injector head and a copper C101 pintle

The dual-pass regen architecture and slotted pintle are the two key changes from the Fenton baseline, both selected to optimise C* and Isp within the constraints of additively manufactured aluminium.

The chamber print - why PCBWay

The combustion chamber is the most critical component of Spectre, and it can only be manufactured by metal SLM 3D printing. The chamber integrates 54 helical regenerative cooling channels of 1.5 mm depth, with widths that vary along the chamber profile from 1.5 mm at the throat to 4.3 mm at the wider sections, over ~300 mm helical length per pass. It also integrates two manifolds, BSPP instrumentation ports, and the chamber profile, all in a single AlSi10Mg print.

This geometry cannot be machined conventionally. The 30° helical channel angle, the integrated manifolds, and the sub-millimetre wall thicknesses between the chamber and the cooling channels all demand SLM. Print quality is the single biggest manufacturing risk on the project. Surface roughness inside the channels affects coolant pressure drop, and any trapped powder in the channels would block coolant flow and risk chamber burn-through during firing.

This is where PCBWay's metal SLM service is genuinely make-or-break for the project. We need:

• Material: AlSi10Mg
• Geometry: Ø90 × 200mm, integrated 30° helical regen channels
• Finish: as-printed
• Quantity: 1
• Critical: complete de-powdering of internal regen channels, verifiable through the dedicated bottom BSPP ports

The estimated value of the chamber print is around £1,000.

Why PCBWay support matters

Spectre's success depends entirely on the print quality of this single component. Sponsorship from PCBWay would directly enable:

• A successful first-year university team entry to R2S, building UH Rocketry's institutional capacity for liquid propulsion
• Demonstrating PCBWay's metal SLM capability on a complex aerospace application that will be hot-fired publicly at a national competition

Visibility and collaboration

In return for sponsorship, we'd be glad to offer:

• PCBWay logo placement on the engine and test stand
• Sponsor acknowledgement in our final R2S competition report and presentation
• Photo and video assets from the hot-fire test, free for PCBWay's marketing use

Acknowledgement

We'd be honoured to work with PCBWay on this, as Spectre is UH Rocketry's first university-team liquid bipropellant engine, and the chamber print is the part of the project we cannot do without external manufacturing support. PCBWay's backing would directly contribute to the next generation of UK aerospace engineers and to a successful demonstration of complex aerospace SLM at a major UK student competition.