Greenjets secure $250K grant for UK e-propulsion test site (e-KETL)

The e-KETL project, funded by the NATEP programme, will develop a novel suction wind tunnel concept based on the ejector principle at S&C Thermfluid’s existing Kemble Engine Test Laboratory (KETL) to allow configurable e-propulsor dynamic and cross-wind testing. The facility started life as a gas turbine static test bed and can be converted to an e-propulsor dynamic wind tunnel within 10 days.

The problem for most e-propulsion companies early in their development cycle is the lack of affordable and accurate test facilities to test their propulsion systems at full scale through low to medium speed dynamic conditions, including the study of interactions with the ground. Wind tunnels and truck based dynamic testing are typically the two available options; both with their own significant challenges. Wind tunnels with test sections capable of housing an air taxi propulsor are very expensive ($100K/day) and not appropriate for early development activities. Dynamic truck tests (where the e-propulsor is mounted on a truck) are more cost effective but lack accuracy and repeatability due to the unpredictable incoming flow conditions.

Greenjets faced this very problem with its flagship electric propulsor, IPM500, designed for the air taxi and regional aircraft market. Rather than conceding to one of two available options, the team took on the challenge of going back to the first principles of dynamic testing. In close collaboration with S&C Thermofluilds (UK), we produced a plan for the e-KETL test setup.

The basic concept places a conventional turbofan engine (S&C’s existing Honeywell ALF502) in KETL’s exhaust conduit to eject air at high speed, which in turn entrains and accelerates air entering the facility through the upturned inlet on the opposite side of the building. This achieves comparable mass-flow to conventional low/mid-speed wind tunnels within a modular, interchangeable working section; allowing for the test of various e-propulsors and flight envelope conditions. All of this is possible without large upfront investment and at a fraction of the typical running costs of an existing large wind tunnel.

Planned to open for business 6 months post-project, the facility will provide a significant cost advantage to UK zero-emission aircraft innovators, helping position the UK to lead the global aerospace sector on the path to net zero.

Dr. Guido Monterzino, Greenjets’ CTO: ‘’Our quest for an appropriate test site for IPM500 that is low-cost and accurate produced no plausible options. Going back to first principles led us to this unique ‘ejector principle’ inspired test site that will help us test IPM500 through its paces’’.

Tony Smith, S&C Thermofluids’ Director: ‘’With several e-propulsion companies supporting this Greenjets-led initiative, I look forward to the setup of this facility, which sees a Victorian era invention (steam ejector) solve a 21st century problem‘’

Greenjets is spearheading the adoption of Advanced Air Mobility (drones, air taxis and regional aircraft) through the development of quiet, safe, efficient and cost-effective electric engines. Our team has over 300 years' collective experience from Rolls-Royce, BAE Systems, GE Aviation and Formula 1. Initially targeting the drone market, our products are selling to airframes with payloads of up to 100kg. Our 5-year roadmap sees the production of larger propulsors for the air taxi and regional aircraft markets.

About S&C Thermofluids:
S & C Thermofluids (  provides an applied research capability focused on aspects of fluid flow and heat transfer engineering. The company uses both analysis (computational fluid dynamics) and experimental techniques (such as the Kemble Engine Test Laboratory) to drive the development of new technologies in all branches of engineering, but particularly aero propulsion systems.  The development of the e-KETL compliments its work on hydrogen propulsion systems and ensures that both aspects of sustainable aviation propulsion are pursued.    

About NATEP:
The National Aerospace Technology Exploitation Programme (NATEP) is a £20m programme to support the development of 80 aerospace technologies in the UK aerospace supply chain. The Aerospace Growth Partnership developed NATEP to help small to medium sized suppliers develop innovative technologies - enhancing home-grown capability & nurturing international business opportunities.

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