The Com­ing Age of Emis­sions-free Air­craft

Trillions - - In This Issue -

An in­ter­view with Pro­fes­sor Dr. Josef Kallo of the Ger­man Aero­space Cen­ter (DLR)

On Septem­ber 29, 2016, a 10-minute test flight at Stuttgart Air­port in Ger­many took place that could end up chang­ing the en­tire fu­ture of air travel.

The flight was of the twin-cabin HY4 air­craft, the first four-seater air­craft in the world us­ing emis­sions-free hy­brid fuel cells to fly. It uses hy­dro­gen to gen­er­ate elec­tric­ity in flight and has a cruis­ing speed of 165 kilo­me­ters per hour (or 102.5 miles per hour) and a travel range of up to 1,500 kilo­me­ters (932 miles). It uses con­ven­tional bat­ter­ies to han­dle the power boost needed for take­offs and land­ings. And the only emis­sion it pro­duces is wa­ter va­por.

This rev­o­lu­tion­ary air­craft is the brain­child of a team com­ing from four dif­fer­ent or­ga­ni­za­tions: the air­craft de­signer Pip­istrel, the fuel cell spe­cial­ist Hy­dro­gen­ics, the Uni­ver­sity of Ulm and the Ger­man Aero­space Cen- ter (DLR). And if the de­vel­op­ment of the pro­ject con­tin­ues as planned, in as lit­tle as six or seven years from now the world could see slightly larger planes like this as a min­i­mum ser­vic­ing short-haul flights through­out the world, all with­out adding a sin­gle mol­e­cule of green­house gas emis­sions as part of their travel.

To learn more about this in­cred­i­ble achieve­ment, Tril­lions had the honor to speak with the air­craft’s pro­ject leader, Pro­fes­sor Dr. Josef Kallo of the Ger­man Aero­space Cen­ter and the Uni­ver­sity of Ulm, at his of­fices in Ger­many on Oc­to­ber 22.

Tril­lions: Con­grat­u­la­tions on the im­pres­sive test flight of the HY4 emis­sions-free air­craft that had its pub­lic maiden test flight just a few weeks ago. My un­der­stand­ing is you have the po­si­tion of Head of Pro­ject for the Ger­man Aero­space Cen­ter for the pro­gram.

Dr. Kallo: My role is to have the pro­ject lead from the Ger­man Aero­space Cen­ter, and I’m also work­ing [as]

the pro­ject lead for the Uni­ver­sity of Ulm. So, these two en­ti­ties had the chance to work on this pro­ject.

Tril­lions: Could you talk a bit about the gen­e­sis of the pro­ject, how it got started and even how you put to­gether some of the part­ners?

Dr. Kallo: Ap­prox­i­mately 10 years ago we had the idea in our group to look at the fuel cell as a propul­sion unit for an air­craft. And then we started – in 2009 – the first one-seater, which was the DLRH2 air­plane. And we had a one-seater which flew with the fuel cell. Af­ter that, we had some achieve­ments. We achieved to fly, like, 1,500 kilo­me­ters with that plane. Then it be­came a lit­tle bit qui­eter. So we took the chal­lenge to im­prove the tech­nol­ogy and to im­prove the power of the sys­tem, so we could start work­ing on the HY4, which is what formed this [air­craft] by Pip­istrel, and then which was also im­ple­mented with the fuel cell from the DLR.

So, we started … two years ago. We worked to­gether with Pip­istrel, the Uni­ver­sity of Ulm, Hy­dro­gen­ics. We had a chance to bring very good peo­ple to­gether. And then we joined with H2fly, which is the owner and op­er­a­tor of the HY4 plane. And then we had a chance to start the pro­ject im­ple­men­ta­tion.

The in­te­gra­tion it­self was started in May 2016. And then we had a very in­ter­est­ing and ex­cit­ing time un­til Septem­ber, when the first flight was tak­ing place. Tril­lions: That’s an in­tense sched­ule. I guess it helps that you had the ear­lier ver­sion, where you had a lot of ex­pe­ri­ence with what worked and what things you wanted to im­prove. As a pro­ject man­ager my­self, I can ap­pre­ci­ate that was a quick turn­around even with some of that back­ground un­der your belt.

In terms of the pro­ject it­self, I’m cu­ri­ous about the whole na­ture of the de­sign of the air­craft and what’s very dif­fer­ent from tra­di­tional air­craft. One thing I know about, for in­stance, is that fuel cells pro­vide a good steady stream of power, but if you need that ini­tial boost to take over or what­ever, they aren’t nec­es­sar­ily as ef­fec­tive at things like that. I’m sure the en­gine’s dif­fer­ent. And I can al­ready tell, from the im­ages of the air­craft and all, that there are things you did to take ad­van­tage of ef­fi­cien­cies in flight, of hav­ing the Bernoulli ef­fect have some [larger] ef­fects. What was dif­fer­ent about the air­craft ver­sus other types of air­craft that one might con­sider in short-haul flights – and things like that?

Dr. Kallo: First of all, I think for­mally [that the] G4, which was built by Pip­istrel and was de­vel­oped for a bat­tery – elec­tric – propul­sion, was a very, very good start. So, when I saw the plane a cou­ple of years ago, then I could in­stan­ta­neously imag­ine to see where the hy­dro­gen stor­age sys­tem can be built in, where the fuel cell can be im­ple­mented and also where the re­main­ing bat­ter­ies for the high-power phase can be im-

ple­mented. Then we had to change the bat­tery loads from the G4 to the HY4, and we min­i­mized the bat­tery, from some­thing like 500 kilo­grams to some­thing like 100 kilo­grams. In ad­di­tion, we in­stalled hy­dro­gen stor­age sys­tems in [the] fuse­lage, be­hind the pas­sen­gers. And then we had also the fuel cells im­ple­mented in the mid­dle part. So I think this is the big dif­fer­ence com­par­ing [to] the G4.

Also the range can be im­proved. With our hy­dro­gen sys­tems to­day, we have a range of around 750 to 800 kilo­me­ters. With im­proved tech­nol­ogy for the stor­age units, we can achieve 1,300 to 1,400 kilo­me­ters of range. I think this is due to the very high ef­fi­cient shape of the air­craft, so we can fly with speeds up to 250 kilo­me­ters per hour but cruis­ing at about 160 to 170 kilo­me­ters per hour. And there the plane is very, very ef­fi­cient. So I think these two points, the ef­fi­cient air­plane and the high ef­fi­ciency of the fuel cell pro­vid­ing elec­tric en­ergy for the mo­tor in flight, dur­ing cruise, these are the spe­cial­ties of this plane.

We still need a bat­tery. We could fly also with­out [the] bat­tery, also dur­ing the start phase. But then we are car­ry­ing too much fuel cell in­stalled power, com­par­ing to a bat­tery. So the per­fect match is to have a small en­ergy bat­tery with high power and a very high en­ergy fuel cell hy­dro­gen sys­tem with mid­dle power. So this is what we have done, and this matches very well.

Tril­lions: Did your fuel cell de­vel­oper, Hy­dro­gen­ics, use any­thing un­usual for this? Ei­ther more compact, higher en­ergy stor­age ca­pac­ity or a dif­fer­ent type of cell?

Dr. Kallo: First of all, we have to look at the hard­ware. And there were some changes which Hy­dro­gen­ics brought in due to our re­quire­ments. And in the sec­ond step, we learned a lot from Hy­dro­gen­ics, so we un­der­stood how they deal with the con­trols. Then we made some sug­ges­tions how to change it, and they had some sug­ges­tions for us for the low-pres­sure op­er­a­tion. It was a very fruit­ful work to­gether, and we had to change the hard­ware [and] also to change the soft­ware and the con­trols.

I think that has to be done also, in the next ver­sion, then, to get to much higher al­ti­tudes than we are fly­ing to­day.

Tril­lions: You talked about how fast it can fly, as well as the range. What is the al­ti­tude that you’re able to achieve with the cur­rent air­craft?

Dr. Kallo: With the cur­rent air­craft, which is the first step, it’s some­thing around 3,000 me­ters, which is 10,000 feet. We could fly higher, but we didn’t ad­just the con­trols for it. So it’s a soft­ware thing which we have to ad­just. We know how to deal with higher al­ti­tudes and what is im­por­tant, but we had 10 hours of flight, all around a cou­ple of thou­sands of feet. And at the mo­ment the plane is [de­signed] for 10,000 feet max­i­mum.

The next step will be to go to 5,500 me­ters, which is then some­thing around 16,000 to 17,000 feet.

Tril­lions: That’s im­pres­sive that you’re able to make that jump, be­cause I’m sure the air­craft it­self changes, to ac­com­mo­date thin­ner air, lower pres­sures, some of the things that you were talk­ing about, and it sounds like [you have] well un­der con­trol.

When you think of con­ven­tional air­craft, there is ser­vic­ing of the air­craft when it lands. If this be­comes a com­mer­cial type of thing, what is the con­cept of ser­vic­ing and things like that like for this kind of an air­craft? Imag­ine the fu­ture, as op­posed to where it’s at right now.

Dr. Kallo: Our con­cept is, for this kind of plane, to have high range, to min­i­mize the needed in­fra­struc­ture for re­fu­el­ing. I don’t think we will travel in such a plane for, like, five to six hours. This is the en­durance of this plane. I think this plane can be used for trav­el­ing 100 to 200 kilo­me­ters, to con­nect big cities or to con­nect places in the out­doors where there is no road in­fra­struc­ture or it’s not easy to go there.

So this could be some­thing which we could use as a four-seater, maybe as a six-seater.

What we see is that this tech­nol­ogy is able to be im­proved, in terms of power, by us­ing mo­du­lar sys­tems. Our cal­cu­la­tions and also our models show that, let’s say, an eight-seater is def­i­nitely fea­si­ble to fly around 150 knots and also have a range of around 1,000 kilo­me­ters. With that, we can do small re­gional traf­fic.

That’s not the end of the vi­sion. From to­day’s per­spec­tive, I can say our models show that we could build a 40-seater with a range of also around 1,000 kilo­me­ters and with a cruise speed of around 220 to 230 knots. This could be some­thing which is in­ter­est­ing then as a re­gional air­craft, fly­ing from smaller air­ports. We have some­thing like 300 of them in Ger­many, fly­ing from smaller air­ports to big­ger air­ports or con­nect­ing re­gional air­ports.

There could be a very good busi­ness case, yes.

Tril­lions: I could cer­tainly see that in a lot of places. There are both the emerg­ing mar­kets that are get­ting very busy where this could be used, [as well as in places like] Cal­i­for­nia, for ex­am­ple, [where] there are a lot of short-haul flights that might be more ef­fi­cient with some­thing like this.

What is next in your plans for this? I know that you’re go­ing to go through fur­ther demon­stra­tions of this air­craft, but maybe you could give some ideas of what’s go­ing to hap­pen next.

Dr. Kallo: From our per­spec­tive, we now have to look at higher ef­fi­cien­cies on the fuel cells. We will im­prove from some­thing around 50 to 53, 54 ef­fi­ciency on the fuel cell it­self. This will be done in the next six to nine months.

And then we would like to start a cam­paign to test the air­plane un­der re­al­is­tic daily con­di­tions. So [as] to see how ro­bust is the sys­tem, to see what is not only the cal­cu­lated range but also what is also the re­al­is­tic range, with cli­matic changes and things like this. This is our next step. We will go into im­prov­ing the ro­bust­ness of the sys­tem. My feel­ing tells me that there is no “no go” on the physics side. It’s only en­gi­neer­ing work and de­vel­op­ment. And if this hap­pens the next three years, then we have a very good [chance] to put also not only a per­mit to fly on this plane but also then to have a cer­ti­fi­ca­tion for this power train.

Our goal is to have, in three years from now on, a highly ef­fi­cient elec­tric power train based on hy­dro­gen and bat­ter­ies and fuel cells. And then we can start think­ing about im­ple­ment­ing this power train into new air­craft con­cepts like con­cepts with maybe shorter take­off ca­pa­bil­ity with dis­trib­uted propul­sion, but maybe also in con­cepts for small he­li­copters and so on.

Tril­lions: In terms of com­mer­cial­iza­tion, do you have a guess at when you think it might be pos­si­ble for air­craft like this to start be­ing used com­mer­cially? Just based on your own feel­ing on how long it’s go­ing to take to get there, as well as, I’m sure, that lit­tle mi­nor is­sue of fund­ing to make all that stuff hap­pen.

Dr. Kallo: [Laughs] I know this. At the mo­ment, with the right fund­ing, I can imag­ine to say, from now on in three years we can start with the cer­ti­fi­ca­tion for a prod­uct. Then in some­thing like six to seven years I can en­vi­sion a first prod­uct. But I think we need this time to step into this prod­uct.

HY4 team: Tine To­ma­sic, Vid Plevnik, Fraci Po­pit, St­ef­fen Flade, Thomas Stephan, Henry Erhardt, Paolo Ro­mag­nolli and the Pi­lots: Saso Knez, Jo­hannes An­ton and Nejc Fa­ganelj. Photo © Jean-marie Ur­lacher

Photo © Jean-marie Ur­lacher

HY4 in flight.

Photo © Jean-marie Ur­lacher

HY4 tak­ing off.

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