Blog of RENAULT NISSAN Alliance

Yves Rossy (aka Jetman) came to TED Global 2011 with perhaps the most exciting presentation and profile, after all he embodies one of the oldest aspirational dreams for humans: the desire to fly! Powered by four jet boosters he has taken the passive gravity-driven experience of free-fall and extended ‘flight’ times with his ground-breaking daring and equipment.

Yves’ display of flying kit at the conference was next door to the Alliance booth, so after tempting him into the very down-to-earth Renault Twizy, we sat down to discuss his remarkable project. Currently fuelled by kerosene (aviation fuel), I wondered what vision Jetman had for future propulsion technology, and I was surprised by his futuristic vision: Yves is looking for some help from seriously disruptive innovation!  

With the way that you use propulsion you need a big kick- so you’re using fossil fuel (kerosene), how do you see this developing as far as the possible means of propulsion goes? Do you ever see the time when you’ll be using electrically driven propulsion?

‘Yes! Yes! Because actually I’m using mini-jets, there’s one advantage in that it’s really small- if I have to use an electric motor actually I need propellers, and propellers are quite big to put on just one guy, and if you want to have the efficiency, then you take the risk of becoming like a salami- cut in slices! That’s why actually it’s a little bit tricky- I  thought about something they’re using on hang gliders; they’re called doodlebugs, it’s a mini thermal engine running on gas,  but there is a propeller pushing- really small, a one-metre diameter propeller pushing the guy on his feet, and he can take off like that it’s enough for the surface of a hang glider, and I thought about something like that for me.’

‘It’s quite complicated, there are two things. The energy I need is quite big, because I’m a big drag. And the propeller I need… the efficiency of a propeller is much better at the speeds I am going at than a jet engine- a jet engine is good for high speeds, I’m going slowly: in terms of aerodynamics up to 300km/h is slow. A jet is becoming good from 3-400km/h. So I am using the wrong thing, but it’s small and it works.’

‘So we have to find a compromise in storing this energy- actually the batteries are nice in the model of flight technology, with have Li-PO batteries and solar impulse is using battery technology but it’s heavy. And to fly, particularly with the surface I have, it will be too heavy- so I hope there will be better batteries, and as soon as I have this kind of energy I will really go in that direction, to have an electric motor, with batteries, because of the efficiency of the propeller it would be better,  and also the efficiency of the electric motor- it’s about 90-95%: a piston engine- a good piston engine- has about 30%, so that means I’m full of hope that, as we are pushed to find solutions with zero emissions because of the global warming, I hoping that the technology will soon in the next 10 or 20 years be that we can store enough electricity that I will have enough  power to propel me in the air.’

Practically speaking, what’s the optimum size of propeller for you: is this a turbine?

‘Actually, there are some studies, some tests on engines with fans, like turbofan engines we have on jumbo jets and so for model airplanes. But that’s aerodynamics: small is bad… the bigger you are, the better it is in terms of aerodynamics- also the aerodynamics of the fan. I do not have a university working on mini-fans, so I’m waiting on these kind of studies. There are students in universities doing work on that; everywhere in the world  (and you can go on the Internet…) there is a big research in that direction, and I hope that something comes. So, something as efficient as a propeller, but much smaller.’

If you had a wish list for your ideal setup, propulsion system, energy storage system, size of the turbofan- what would you have? How many fans would you have?

‘I wouldn’t have any fans! My wish….. have you seen ‘Ironman’? This kind of energy I need…. And afterwards you don’t need wings, you have enough energy to push you in the air…. As we have four members that means four points, four possibilities of points of stability. If you push on four points and you can regulate these, then you find stability- in my hands, on my feet, four pushing points then you fly… if you have enough energy. So how do you put this energy- you know, that’s what is extraordinary in these science fiction films… so the ideas are here, the solution not yet. But it pushes the imagination and the creation in that direction. So for me that would be the ultimate thing, you don’t need any other apparatus, just a littlesource of energy- just the same as he has on his chest- and this energy is OK for a one and a half hour film (laughs) to push him supersonic in the air. So that would be my real wish!’

So, our modern-day Icarus continues: searching for exactly the right kind of feathers, and hopefully keeping well away from the sun!