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Ich habe verstanden.

Revolutionary ULF-1 Concept "Made in USA"

Veröffentlicht am 21. Dezember 2014
Zugriffe: 3791

UL-Segelflug.de/images/TC/ULF-1_Electro_2-mot_Holliday-Obrecht_jpgTaking a look at different ULF-1 builds one can see, that nearly each single ULF-1 is unique for itself. Despite the fact, that all builds are based on the design and the drawings of Dieter Reich and Heiner Neumann, the final build includes most of the time different alterations, matching the ideas and personal needs of the builder. But most of the alterations are only to be detected by a very close look to each ULF-1.

With the present ULF-1 project in Charlotte / USA, Holliday Obrecht and his crew plan to realize a few additional and most remarkable alterations in the common design.

UL-Segelflug.de/images/GT/ULF-1_Teil-Baugruppe_Holliday-Obrecht.jpgHolliday Obrecht (right/front with glasses) with part of his "build-crew"

The technical amendments "Made in USA" are so far unique in its kind and they sure mark an absolute quantum-leap, perhaps comparable to the differences between the original "Zeppelin constructions" and today´s ultra-modern Zeppelin NT. The suffix "NT" stands for New Technology, because with the only exception of the outer-shape, the current Zeppelin NT has little in common with the former designs of the Count Zeppelin.


While the "Obrecht-variant" is wearing the modest Type-designation ULF-1 E, it is surely not difficult du guess, that the suffix "E" stands for "Electric". But the electric-drive marks only a small, albeit crucial part in the numerous catalog of technical changes by Holliday Obrecht and his team. With the respect of the many design-changes compared to the original-design, the more appropriate model-designation "ULF-1 NT" would sure match the construction much better.

UL-Segelflug.de/images/GT/ULF-1E_Anpassung_SL-Nasenbeplankung.jpgFinal adaption of nose-covering on the vertical-fin

UL-Segelflug.de/images/GT/ULF-1E_Detailansicht-Seitenleitwerk.jpgDetailed view to vertical-fin top

Describing all various improvements and alterations of the "Obrecht-variant" would be far behind the scope of this blog, but a detailed description and project-specifications will be available of course at a later date and will be published in "F&E" at our site.

Brief overview of modifications:

  • 2 Electric-motors with four-bladed folding propellers (Pusher) at both wings trailing-edge, left and right near the fuselage
  • extending the fuselage nose-section by 200 mm to the front, enabling the pilot a more comfortable and slightly reclined seating position also to compensate the tail-down directed moments by the installation of the two motors and the battery-pack
  • CNC-cut Styrofoam-Ribs, instead of the usual pine- and plywood-ribs, while the Styrofoam-ribs will become reinforced mouldings on their top- and bottom-side
  • additional, diagonal support-ribs will be installed to enhance the structure of the wings
  • electrically powered spoilers, using servos available for big RC-Models
  • electronic-digital, extremely lightweight instrumentation, consisting of Airspeed-Indicator, Altimeter, Vertical-Speed Indicator and Compass
  • Kevlar-Control cables instead of usually used steel-cables as a further contribution to weight-savings
  • steerable nose-wheel for taxiing on the ground

As with all projects of motorized ultralight gliders, the biggest challenge for the design- and construction-team will also consist in this E-project to comply to the limited maximum empty-weight of 115 kg, as required by the Federal Aviation Authorities (FAA) FAR Part-103. With the installation of Styrofoam-ribs, Kevlar control-cables and ultralight aircraft-instruments, one or the other Kilogram of weight can be avoided for the benefit of motor- and battery-pack installations.

UL-Segelflug.de/images/GT/ULF-1E_Detailansicht-Rumpfspant_im_Bau.jpgView of a major fuselage-part perfectly executed

That Holliday Obrecht and his team are not doing just a "quick and dirty job" by the build of the ULF-1 E (NT), but master the art of wooden-glider craftsmanship in perfection, this can be seen impressively in the picture above. Quite unlikely, that the job they all do could be done any better - Chapeau! The maiden-flight can not be expected before an other few years. But this should hardly suprise, taking the numerous design-changes into considerations.

Contrary to the original design of the ULF-1 which can be foot-launched, this launching-method of course is not given in this present project, due to the additional weight of the two motors and battery-pack. But their is no need for foot-launching too, as the Obrecht ULF-1 E is designed for self-launching at the local airstrips in the flat-lands, which is one of the highest target to gain.


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