A Norwegian start-up is hoping its small electric-powered ducted-fan engine for unmanned air vehicles (UAVs) can spearhead a move up the weight class into commercial aviation applications.
Stavanger-based SiriNor – which has an engineering subsidiary in India – has been ground testing a subscale proof-of-concept version of its “tip-driven engine”, which successfully generated thrust of 22lb (0.09kN), taking the basic architecture to technology readiness level 6 (TRL6), the firm claims.
Its first commercial product, however, will be an order of magnitude larger: capable of producing 200lb of thrust, it will feature a 30cm (12in)-diameter fan and weigh 15kg (33lb), says chief executive Ivar Aune.
To reach the required take-off thrust, 100kW of electrical power will be needed, falling to 35kW to achieve output of around 55-66lb in cruise. Flight testing aboard a UAV is anticipated in the third quarter.
SiriNor’s design directs some of the air flow through secondary ducts to a one- or two-stage axial compressor assembly driven by small electric motors.
The compressed air is then directed onto the tips of a tip turbine fan, which can be attached to another fan via a gear mechanism if needed.
This “tip-driven fan” configuration, says Aune, uses 20-30% less force to rotate the fan than a hub-driven design.
Additionally, because there is no combustion, the engine can be made from standard aerospace materials rather than exotic super-alloys required to withstand the ultra-high operating temperatures of a modern jet engine, “dramatically reducing both manufacturing complexity and cost”.
Aune says the “material flexibility” also allows the company to 3D print a large proportion of the engine’s components, speeding the prototyping process and “opening the door to a more geographically diverse, resilient, and cost-efficient supply chain”.
While it continues testing the UAV prototype, SiriNor will begin assembly of a larger 1m-diameter engine designed for ground-effect vehicles and capable of producing around 5,600lb of thrust – more powerful than the Williams International FJ44 that equips several business jets.
Aune sees service entry for the UAV engine in 2026, followed by the model for ground-effect vehicles in 2027. But SiriNor’s ambitions do not stop there: it argues that the scalability of the design will allow it to tap into commercial aviation’s decarbonisation agenda as well.
Such an engine would feature a fan diameter of 2m or above and be ready for service entry by the end of the decade.
According to the firm’s calculations, an engine with a 3m diameter should be capable of producing thrust in the 56,000lb range – roughly on a par with a Rolls-Royce RB211.
“The fact that we use the same lean-cost design architecture across a huge range of aircraft sizes, means that we have a product which can help unlock the vast potential of sustainable and affordable aviation at scale,” says Aune.
SiriNor has so far raised $1 million in early-stage funding, with an additional $5 million to come later this year.
“We’re proud of the fact that we’ve taken a groundbreaking engine design to TRL6 in less than five years on a budget of about $500,000,” adds Aune.
Should the company opt to focus solely on the UAV market, it forecasts a requirement for around $5-10 million to successfully commercialise the engine, $25-35 million to address the ground-effect vehicle market, and $75-105 million for commercial aviation applications.
