Developing aerospace applications for hybrid propulsion

What is different about Turbotech’s turbogenerator?

In fact, it’s the first on-board power generator. Our turbogenerator is designed to be embedded in a hybrid propulsion system to power of all types of aircraft. It can be activated in all or part of the flight phases, depending on the needs of the aircraft. The electric power is optimally distributed according to the flight phases, either for propulsion or for recharging the batteries.

The turbogenerator is very light (45 kg) and compact, so it is particularly suitable for small aircraft. If combined with 40 kg of fuel, it provides a performance equivalent to one ton of lithium-ion batteries. This lightness, combined with low fuel consumption and the ability to recharge batteries in flight, means it has potential for electrically powered aircraft.

The main innovation lies in the heat exchanger; as it is embedded in the turbine, it can recover the energy of the exhaust gases, and thus reduce fuel consumption.

Last but not least, our turbo-generator is a multifuel device: it can be used with biofuel, diesel, natural gas, or hydrogen. In the latter case, this means there is no emission of pollutants.

 

Can you tell us how the project came about and how the collaboration with Safran first developed?

When we came up with the idea for this turbogenerator, we started working on the project during our free time, during weekends and vacations. There are six people on our team, five of whom work at Safran, and we are also supported by a Breton partner, Le Guellec, with whom we have co-developed the turbogenerator heat exchanger.

In 2010, we won a prize from the Ministry of Higher Education and Research for the first phases of the project. Then we asked Safran to help us set up our company. This process resulted in the development of a demonstrator in 2015, which ran on a test bench and worked very well.

Today, we receive technical support from the engineering departments of several Group companies, in particular Safran Aircraft Engines. And with the support of Safran Tech, we are currently studying various possible applications. We hope to keep working with Safran on co-engineering and co-development.

The fact that we have an independent organization means we can stay agile, so we can move through the various development steps quickly. We’re working on a pre-prod engine now. This September, we’ll be relocating our new company, Turbotech, to Saclay, near Safran Tech. By then, we will have finished raising capital from the various industrial players and investment funds.

 

What impact will your innovation have on the future of air transport?

Long story short, the goal is to enable aircraft to do everything a helicopter can do today, but for the price of a passenger vehicle. We’re seeing new aircraft concepts appearing today. For example, multirotors that take off and land vertically. The turbogenerator would be perfect for them.

Meanwhile, we’re working on our concept to tailor it to light aircraft (55 kW, or 75 bhp) and large drones (like the Patroller, for example). We’re also working with Safran Tech to scale up the system and increase its power. In a decade, we could be ready to supply turbogenerators for 10- to 20-seater aircraft. And, further down the road, we could be powering regional aircraft or small airliners. So we could contribute to developing the more electric aircraft.

The next step: to fine-tune a demonstrator by mid-2018, and run it on test benches simulating a full hybrid architecture. The plan is to start marketing the turbogenerator in 2019, on aircraft with hybrid architectures. The first potential customers are already showing interest.