G.Haddow, P.Grosz The German Giants (Putnam)

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.)

J.Herris German Aircraft of Minor Manufacturers in WW1. Vol I (A Centennial Perspective on Great War Airplanes 49)

Union

   The Union Flugzeugewerke was established in 1912 in Berlin and built a small number of types, one of which was the G.I bomber. The crash of the Union G.I was the end of the Union company, which had to be sold.


Union G.I (R.I)

   On August 6, 1915, the Feldflugchef (Chief of Field Aviation) suggested pressing Daimler to manufacture multi-engine G-type aircraft, and Daimler agreed to expand into aircraft production.
   Daimler's first bomber involvement was with the Union G.I (also known as the R.I), where it provided the engines. The Union G.I was a biplane with four 110 hp Mercedes engines of inverted configuration. The engines were mounted as tractor-pusher combinations in nacelles attached to the lower wing. Four engines were installed for improved reliability, and the tractor-pusher combination enabled the designers to mount all the engines near the fuselage to minimize asymmetric thrust due to engine failure. The compact design also provided good fields of fire to the fore and aft gunners, each of whom were to have a single flexible machine gun.
   On May 17, 1915 Daimler agreed to inspect the aircraft, and especially the engines, prior to its first flight that was scheduled for the following week. At some point during its flight testing the Union G.I carried 18 people, an unofficial world record, before being accepted by the Fliegertruppe. The Union G.I was transferred to Feld-Flieger Abteilung 16 and was attached to that unit from June 1 to its crash on September 1 at Schloss Eberspark near Schneidemuhl.
   By the time of its crash the Union G.I had been named Marga-Emmy. With Lt. Neuensitz as observer, the pilot Thassler landed the G.I hard, breaking off the tail. Although the nose dug in, neither crewmen was injured. However, that was the end of the Union G.I. More importantly, it was the end of the Union company, - the Fliegertruppe cancelled any further support and the company had to sell its assets to Norddeutsche Flugzeugwerke.

M.Dusing German Aviation Industry in WWI. Volume 2 (A Centennial Perspective on Great War Airplanes 85)

Union Flugzeugwerke, Berlin-Teltow (Mark)

Aircraft Development:

<...>
  Union engineers Baurat Rittberger and Karl Schopper began the design of a large four-engined bomber in 1914, classified in the Grossflugzeug category because the engines could not be serviced in flight. Constructed of wood with fabric covering, (some parts may have been plywood covered) and wire bracing. The tail unit comprised a single tailplane with elevator with a single fin carrying a rudder and two auxiliary rudders at approx half tailplane span. The G-type aircraft can be assumed as one of the first German 4-engined planes.
  At the successful Idflieg inspection on 13 April 1915, the airframe construction was described as good, but the low cruising and maximum speeds were criticised as well as the disappointing useful load. Flight trials began in May 1915 but the first G.I was damaged and there is no evidence of further flying. The machine was not accepted by Idflieg, so the designation G.I may be spurious.
  The second G.I named "Marga-Emmy" was ordered by Daimler to allow them to rapidly enter the aircraft market. The strengthened second G.I, stationed at Schneidemuhl, flew soon after but was destroyed just before landing on 1 September 1915 after experiencing extreme vibrations from the engines during flight. Development continued as the Daimler R.I.
  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.