Thrust for the future

“Answering tomorrow’s challenges”: For MTU Aero Engines, this principle is both a motto and a respon­sibility. Never before has the company had such good answers ready as today.

06.2019 | Text: Martina Vollmuth

Text:
Martina Vollmuth holds a degree in journalism and trained as a copy editor for daily newspapers. She is the official spokeswoman for technology at MTU.

For decades, three let­ters in avi­a­tion have stood for in­no­v­a­tive en­gine so­lu­tions: MTU. The en­gine ex­perts in Mu­nich have re­al­ly made a name for them­selves over the years, re­peat­ed­ly com­ing up with valu­able tech­no­log­i­cal in­no­va­tions. With their con­tri­bu­tions to the Geared Tur­bo­fan™ (GTF) en­gine, they are im­pres­sive­ly shap­ing de­vel­op­ments in the in­dus­try of the present while prepar­ing to shape the fu­ture like nev­er be­fore in the com­pa­ny’s his­to­ry: MTU’s unique ex­per­tise means it is ide­al­ly placed to tack­le the key mis­sions of to­day and to­mor­row: mak­ing com­mer­cial en­gines even more ef­fi­cient and en­vi­ron­men­tal­ly friend­ly and mil­i­tary en­gines even more pow­er­ful.

AEROREPORT series: 50 years of innovation at MTU

“Nev­er has MTU had such a de­fin­i­tive tech­nol­o­gy roadmap as to­day,” ex­plains COO Lars Wag­n­er. “We’re con­scious of our ­re­spon­si­bil­i­ty for sus­tain­able, emis­sions-free fly­ing. That’s why we’re al­ready in­vest­ing to­day in pi­o­neer­ing tech­nolo­gies for the avi­a­tion of to­mor­row.” Wag­n­er ex­plains that, from 2030 on­ward, the com­mer­cial seg­ment will be clear­ly ori­ent­ed to­ward the next gen­er­a­tion of the Geared Tur­bo­fan™, while in the mil­i­tary ­seg­ment it is the NEFE (Next Eu­ro­pean Fight­er En­gine) that will de­ter­mine the com­pa­ny’s di­rec­tion. He con­tin­ues: “In the com­mer­cial seg­ment, we’re re­search­ing sev­er­al evo­lu­tion­ary ­ap­proach­es that are al­ready pos­si­ble to­day thanks to sus­tain­able e-fu­els. At the same time, we’re look­ing in­to al­ter­na­tive en­gine con­cepts rang­ing from hy­brid-elec­tric flight to fu­el cells.”

“Never has MTU had such a definitive technology roadmap as today.”

Lars Wagner, Chief Operating Officer MTU Aero Engines, Munich

Pro­file of com­mer­cial avi­a­tion in 2050

How­ev­er, MTU’s ex­perts are not sat­is­fied to leave it at that; they are cast­ing their gazes fur­ther in­to the fu­ture. Part of a small band of vi­sion­ar­ies world­wide, they are al­ready work­ing with part­ners from in­dus­try and re­search on ideas for the com­mer­cial en­gines that could fly from 2050 on­wards. Wag­n­er ex­plains: “MTU is work­ing out rev­o­lu­tion­ary en­gine con­cepts to achieve the am­bi­tious goals of Flight­path 2050.” These new en­gine so­lu­tions have to go be­yond to­day’s tech­nol­o­gy, with emis­sions-free flight the greater goal.

Video: “Answering tomorrow’s challenges” Article with video

“Answering tomorrow’s challenges”

MTU Aero Engines is working on the aviation technologies of tomorrow, today. MTU is presenting a detailed look at the key technologies MTU contributes to the next generation of Geared Turbofan™ engines as well as the 2030+ and 2050 propulsion concepts. To the video ...

The MTU ex­perts have sev­er­al spe­cif­ic en­gine con­cepts in view, in­clud­ing the com­pos­ite cy­cle and the STIG cy­cle en­gine. Such “rev­o­lu­tion­ary” so­lu­tions in­volve en­tire­ly new tech­nol­o­gy. By con­trast, MTU char­ac­ter­izes the fur­ther de­vel­op­ment of the ­ex­ist­ing Geared Tur­bo­fan™ tech­nol­o­gy as “evo­lu­tion­ary”: the sec­ond GTF gen­er­a­tion still of­fers con­sid­er­able po­ten­tial. Once it has been fur­ther op­ti­mized, it will dra­mat­i­cal­ly re­duce emis­sions and is due to be air­borne by the mid-2030s.

Then there will need to be a tech­no­log­i­cal leap for­ward to de­vel­op tech­nolo­gies and con­cepts that will pave the way for large­ly emis­sions-free flight—this is the re­spon­si­bil­i­ty of the Eu­ro­pean avi­a­tion in­dus­try. Re­source­ful MTU de­vel­op­ers have come up with two ap­proach­es and are com­bin­ing the tried-and-test­ed gas tur­bine en­gine with brand new tech­nolo­gies: in the com­pos­ite cy­cle ap­proach, the con­ven­tion­al high-pres­sure com­pres­sor sys­tem is to be sup­ple­mented by a pis­ton com­pres­sor and en­gine. “This will al­low us to sig­nif­i­cant­ly in­crease ther­mal ef­fi­cien­cy,” says Dr. Ste­fan We­ber, Se­nior Vice Pres­i­dent Tech­nol­o­gy & En­gi­neer­ing Ad­vanced Pro­grams in Mu­nich. The STIG cy­cle en­gine, mean­while, in­te­grates a steam pow­er process in­to the gas tur­bine process­es. This in­volves us­ing a gas tur­bine with steam in­jec­tion to feed the heat of the ex­haust stream back in­to the process in­side the en­gine. The wet com­bus­tion would sub­stan­tial­ly re­duce both CO2 and NOx pol­lu­tant emis­sions. “We’ll have to see which ap­proach ul­ti­mate­ly of­fers greater po­ten­tial and is eco­nom­i­cal­ly fea­si­ble,” We­ber says. If this turns out to be the STIG cy­cle en­gine, it will not work in the cur­rent air­craft ar­chi­tec­ture, thus call­ing for a new con­fig­u­ra­tion.

Sus­tain­able, re­new­able fu­els

Work on these two MTU pi­lot con­cepts is be­ing ac­com­pa­nied by oth­er ac­tiv­i­ties. “These mea­sures alone won’t be enough for us to reach the am­bi­tious goals for 2050,” says We­ber. “They will get us a good part of the way there, but by no means will they let us achieve them com­plete­ly. We need to close the re­main­ing gap through the de­vel­op­ment of sus­tain­able fu­els.” The idea is to shift away from con­sum­ing fos­sil fu­els to­ward sus­tain­able, re­new­able fu­els. “We want to en­cour­age their use,” We­ber says. Promis­ing ap­proach­es for pro­duc­ing syn­thet­ic fu­els are of­fered by so­lar en­er­gy and by elec­tric­i­ty—pro­vid­ed it is gen­er­at­ed sus­tain­ably. The lat­ter tech­nol­o­gy is al­ready avail­able to­day. One of the ma­jor ad­van­tages of syn­thet­ic fu­els is that they don’t re­quire any new in­fra­struc­ture; they can sim­ply be “dropped in” to ex­ist­ing pe­tro­le­um-based in­fra­struc­ture. To com­plete­ly cut out NOx emis­sions as well, there’s no get­ting away from fu­el cells—mean­ing fly­ing with hy­dro­gen. MTU has this tech­nol­o­gy in its sights, too.

Profile of commercial aviation in 2050

**Composite Cycle Engine:** Combining gas turbines and piston machines is an ap­proach that dates back to the 1950s—however, today’s commercial air­craft require a much higher level of performance. MTU has developed and patented a new concept for this combination. Hover over the image for a bigger view

Composite Cycle Engine: Combining gas turbines and piston machines is an ap­proach that dates back to the 1950s—however, today’s commercial air­craft require a much higher level of performance. MTU has developed and patented a new concept for this combination.

aeroreport_composite-cycle-engine

Composite Cycle Engine: Combining gas turbines and piston machines is an ap­proach that dates back to the 1950s—however, today’s commercial air­craft require a much higher level of performance. MTU has developed and patented a new concept for this combination.

**STIG Cycle Engine:** STIG (STeam Injected Gas turbine) refers to the inte­gration of a steam process into the gas turbine. The idea is to use the energy from the exhaust to increase power output. It should also considerably reduce pollutant emissions in the process. Hover over the image for a bigger view

STIG Cycle Engine: STIG (STeam Injected Gas turbine) refers to the inte­gration of a steam process into the gas turbine. The idea is to use the energy from the exhaust to increase power output. It should also considerably reduce pollutant emissions in the process.

aeroreport_stig_cycle_engine

STIG Cycle Engine: STIG (STeam Injected Gas turbine) refers to the inte­gration of a steam process into the gas turbine. The idea is to use the energy from the exhaust to increase power output. It should also considerably reduce pollutant emissions in the process.

E-fly­ing

One top­ic has been gain­ing more and more pub­lic at­ten­tion re­cent­ly: elec­tric fly­ing. This is be­cause pure­ly bat­tery-dri­ven air­craft fly com­plete­ly emis­sions-free—pro­vid­ed the elec­tric­i­ty they use has been gen­er­at­ed sus­tain­ably. “Emis­sions-free” does not in­clude noise, as this sim­ply can­not be ful­ly avoid­ed when it comes to flight. Re­al­is­ti­cal­ly, how­ev­er, from to­day’s per­spec­tive there are large ob­sta­cles to over­come be­fore we will see pure­ly bat­tery-pow­ered pas­sen­ger air­craft. We­ber elab­o­rates: “Elec­tric propul­sion sys­tems and bat­ter­ies reach per­for­mance lev­els to­day that per­mit their use in pow­er glid­ers, sport­ing air­planes and oth­er air­craft in that class.” But at present, trans­fer­ring this tech­nol­o­gy in­to air­craft in the Air­bus A320 class is im­pos­si­ble, as the bat­tery ca­pac­i­ty falls far short of what’s need­ed. “And we cur­rent­ly see no promis­ing tech­no­log­i­cal ap­proach­es open­ing up in the fu­ture.”

What does seem tech­ni­cal­ly fea­si­ble from to­day’s per­spec­tive are tur­bo-elec­tric or hy­brid-elec­tric sys­tems that in­te­grate the tur­bo­ma­chin­ery and gen­er­a­tor in­to the air­craft fuse­lage. The cur­rent for the elec­tric mo­tors could be gen­er­at­ed by a gas tur­bine; in turn, the elec­tric mo­tors would pow­er dis­trib­uted fans on the wing. Whether there is tru­ly po­ten­tial to be tapped with this ap­proach re­mains to be seen. Suc­cess ul­ti­mate­ly hinges on tech­ni­cal progress in the field of bat­ter­ies and elec­tric mo­tors. MTU has its fin­ger on the pulse here, too, and is in­volved in var­i­ous stud­ies and ini­tia­tives: for ex­am­ple, it is col­lab­o­rat­ing with part­ners to in­ves­ti­gate hy­brid-elec­tric or all-elec­tric pow­er­trains for air taxis or even 19-seater air­craft.

We­ber is cer­tain about one thing: “As a con­cept, the gas tur­bine en­gine will con­tin­ue to hold sway. It’s fit for the fu­ture and holds po­ten­tial for fur­ther op­ti­miza­tion.” Us­ing sus­tain­able drop-in fu­els with the ex­ist­ing in­fra­struc­ture would make it pos­si­ble to quick­ly put a sig­nif­i­cant dent in pol­lu­tion emis­sions. There are two con­ceiv­able ap­pli­ca­tions for the gas tur­bine in air­craft: ei­ther as an im­proved, green­er main en­gine or else as the ba­sis for low-emis­sions hy­brid sys­tems, in­so­far as their in­tro­duc­tion is proven to be ben­e­fi­cial over­all.

MTU has po­si­tioned it­self clear­ly: it re­mains true to it­self and its tra­di­tion, and is eye­ing all pos­si­bil­i­ties for en­sur­ing fur­ther progress in the skies. Af­ter all, as the ex­perts know, the fu­ture of avi­a­tion be­gins to­day.

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