Mercedes Fh 1256

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1913 — 1914 Fh 1256 118 PS

Inverted six cylinder engine, four of which would power the unsuccessful Union G.I bomber in May 1915 Kaiserpreis

Union G.I

In 1912 the Union-Flugzeugwerke G.m.b.H. was founded at Teltow near Berlin by an aircraft designer named Karl Bomhard, who had previously participated in the design of the Lohner arrow-biplanes (Pfeilflieger) in Austria. He was joined by Dr. Josef Sablatnig (in 1913) and Georg Konig. These two engineers constructed the Union arrow-biplanes based on Bomhard's designs, which were then quite the vogue. One of these aircraft won three world-altitude records with passengers for Germany in 1913.

At the end of the year 1914 Union began construction of a large four-engined bomber which fell into the same category as the SSW-Forssman R-plane and, like this machine, the engines of the Union G.I were not serviceable in flight, but its size merits inclusion in this book. On 13 April 1915 the framework of the Union G.I was inspected by Government engineers, who called its construction good, but its estimated speed of 95 km.h. (59-4 m.p.h.) was criticized as being too slow, and its estimated bomb load was considered to be insufficient. It was powered by four inverted 110 h.p. Mercedes engines mounted a tandem pairs in fully-enclosed nacelles on the lower wing. The airframe was typical of the period, constructed of wood, wire-braced and fabric-covered; however, there is some indication that the fuselage was sheathed in plywood veneer. The tail assembly consisted of a single tailplane and elevator surmounted by three parallel rudders, the middle one hinged to a triangular fin. The designers of the Union G.I were Baurat Rittberger and Karl Schopper.

The Union G.I first flew in May 1915, subsequently it suffered damage, but it ultimate fate is unknown. Because Daimler had intentions of entering into the aircraft construction business, it placed an order for a second G.I and transferred a number of workers to the Union shops to learn the aircraft trade. The airframe of the second Union G.I was strengthened, but overall dimension remained the same. This machine, bearing the name "Marga-Emmy" painted on its nose, was stationed at the airfield in Schneidemuhl. During a test flight on 1 September 1915 with pilot Thassler at the controls, severe engine vibrations forced him to make an emergency landing at Schloss Eberspark near Schneidemuhl. The vibrations were so great that the G.I airframe broke apart shortly before touch-down. There were no injuries to the crew. Structural weakness was the cause of the first G.I breaking in two during take-off or landing. The aircraft were not rebuilt, but an improved version was continued as the Daimler R.I and Daimler R.II. On 1 August 1916 the Union-Flugzeugwerke went into liquidation and its assets were taken over by the Norddeutsche Flugzeugwerke, which spent the remainder of the war years repairing aircraft.

SPECIFICATIONS

Type: Union G.I.

 Manufacturer: Union-Flugzeugwerke G.m.b.H., Teltow, Berlin
 Engines: Four 110 h.p. Mercedes Fh 1256 engines (inverted)
 Dimensions:
  Span, 21•0 m. (68 ft. 10 1/2 in.)
  Length, 18•2 m. (59 ft. 8 1/2 in.)
  Height, 3•74 m. (12 ft. 3 in.)
 Areas: Wings, 72-40 sq. m. (779 sq. ft.)
 Weights:
  Empty, 1960 kg. (4321 lb.)
  Loaded, 2765 kg. (6096 lb.)
 Wing Loading: 38•20 kg./sq. m. (7'8 lb./sq. ft.)
 Performance: 
  Maximum speed, 128 km.h. (79'5 m.p.h.)
  Cruising speed, 115 km.h. (71'5 m.p.h.)
  Climb, 
  1000 m. (3281 ft.) in 14•5 mins.
  1500 m. (4921 ft.) in 24•2 mins.
  Ceiling, 3500 m. (11,483 ft.)