Pi­lot Notes

Di­a­mond's diesel-elec­tric hy­brid and other GA news

Pilot - - CONTENTS -

On 31 Oc­to­ber Di­a­mond Air­craft made the first flight of a mul­ti­engine diesel-elec­tric hy­brid­pow­ered DA40 that has been de­vel­oped in col­lab­o­ra­tion with Siemens AG. Dur­ing the twenty-minute flight the air­craft demon­strated all modes of op­er­a­tion, in­clud­ing hy­brid, ‘charg­ing’ and full elec­tric flight, from take­off. The main ob­jec­tive of the joint project is to de­velop an air­craft that has lower fuel con­sump­tion (thus higher ef­fi­ciency), and a lower noise foot­print. ‘The hy­brid pow­er­train will al­low for full elec­tric take­off ca­pa­bil­i­ties with­out the added noise and pol­lu­tion of a com­bus­tion en­gine,’ Di­a­mond says.

The DA40 has been re­con­fig­ured so that a sin­gle com­bus­tion en­gine pow­ers two in­de­pen­dent elec­tric drive sys­tems, each com­pris­ing one mo­tor, bat­tery and in­verter. Mounted on a for­ward ca­nard, the two elec­tric mo­tors can jointly gen­er­ate 150kw of take­off power. A diesel gen­er­a­tor in the nose of the air­craft can pro­vide up to 110kw of power, and two 12kwh bat­ter­ies mounted in the rear pas­sen­ger com­part­ment act as an en­ergy stor­age buf­fer. Through a ded­i­cated power lever, the pi­lot can con­trol the en­ergy flow be­tween gen­er­a­tor, bat­ter­ies and mo­tors, se­lect­ing ei­ther pure elec­tric mode (gen­er­a­tor off), ‘cruise mode’ (in which the gen­er­a­tor pro­vides all power to the mo­tors), and ‘charge mode’ (in which the gen­er­a­tor charges the bat­ter­ies). On pure elec­tric power the DA40 has an en­durance of about thirty min­utes, which the hy­brid sys­tem ex­tends to five hours.

Head of Flight Test Ing­mar Mayer­buch, who pi­loted the air­craft, re­ported: “The first flight ex­ceeded all our ex­pec­ta­tions. The com­bi­na­tion of the hy­brid pow­er­train and the con­fig­u­ra­tion of the air­craft is just per­fect. We reached 130 knots at medium power out­put and climbed to an al­ti­tude of 3,000ft.”

“This is the first se­rial-hy­brid elec­tric plane in the world with two elec­tri­cally-pow­ered free-stream pro­pel­lers and one com­bus­tion en­gine,” says Dr Frank An­ton, Siemens AG’S Ex­ec­u­tive Vice Pres­i­dent, eair­craft. “A dis­trib­uted propul­sion ar­chi­tec­ture opens en­tirely new pos­si­bil­i­ties for the de­sign of highly ef­fi­cient planes−and we have now proven its tech­ni­cal fea­si­bil­ity. Se­ri­al­hy­brid elec­tric propul­sion sys­tems and dis­trib­uted propul­sion ar­chi­tec­tures for us are the key to a more sus­tain­able flight fu­ture also in higher power classes. The Di­a­mond fly­ing test bed will help us to un­der­stand the re­quire­ments for these new propul­sion tech­nolo­gies and to be pre­pared for the chal­lenges of larger-scale ap­pli­ca­tions.”

The next flight tests will aim to de­ter­mine the ex­act ef­fi­ciency in­crease achieved in com­par­i­son to sim­i­lar non-elec­tric air­craft. The air­craft’s noise foot­print will also be mon­i­tored. Fu­ture tri­als will gather knowl­edge on the prac­ti­cal op­er­a­tion of hy­brid air­craft in dif­fer­ent modes and their ef­fects on ef­fi­ciency, range, and en­ergy con­sump­tion.

Head of Flight Test Ing­mar Mayer­buch made the first flight

150kw (201hp) is avail­able for take­off, gen­er­a­tor pro­duces 110kw

Elec­tric mo­tors pro­vide propul­sion, nose houses diesel gen­er­a­tor

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