Dornier Do Y

Dornier Do Y
Type:	Three-engined military land plane, cargo plane and bomber
Design country:	German Empire
Manufacturer:	Dornier works
First flight:	October 17, 1931
Number of pieces:	4th

The Dornier Do Y was a three-engine heavy bomber that could also be used for passenger and freight transport. The aircraft was designed and built in the late 1920s and early 1930s by the aircraft manufacturer Dornier Metallbauten GmbH in Friedrichshafen .

description

The semi cantilevered wing monoplane in all-metal construction with solid suspension had a three-part dreiholmigen, ion-crossed with the wing-Dornier aircraft for the former typical parabolic shaped leading edge. The originally very pointed wingtips later had to be shortened due to the risk of flutter, so that the wingspan was reduced (see technical data). The wing in the engine area was sheet metal and walkable, but otherwise covered with fabric. All oars had auxiliary oars on the outside to reduce the steering force. The suspension struts of the chassis were hinged to the front pillar and two of the motors were attached. The third engine sat on a strut bracket above the wing center section. The propellers could have two blades made of wood, but also two or three blades made of metal. The box-shaped shell hull made entirely of duralumin had the stiffening profiles riveted on on the outside as is customary at Dornier. In addition to the two open driver's seats equipped with double controls (accessible through the hatch in the fuselage floor), compartments for the bombardier, radio equipment and the dropping ammunition to be carried, as well as three open arms, one in the bow and two behind the bomb room for defense back top and bottom. In the former, a single MG Darne was built into the latter on turntables. The front end of the individual aircraft was partly heavily glazed for the bombardier housed there.

History of origin

Dornier Do Y, rear view

The first two of the total of four aircraft built were commissioned by Yugoslavia, but were to be paid for by the German Reich as reparations under the Versailles Treaty , as had already been the case with the delivery of some Do D and Do J to this victorious state. As cargo planes , these two Do Ys with their bows still closed could easily be built at Dornier's main plant in Manzell near Friedrichshafen, although the construction of war planes was still strictly prohibited in the Reich. So was the first flight of the prototype, the Wnr. 232, on October 17, 1931 at the Friedrichshafen - Löwental company airport without difficulty. The second plane was also flown in there. The difficulties began with the payment. From July 1, 1931, Germany's reparations payments were suspended for one year due to the Hoover moratorium named after the American president . In November, the Reich Ministry of Finance therefore refused to cover the costs of RM 570,591.00 that had accrued for the two aircraft, which understandably brought the company into financial difficulties. Only after lengthy negotiations was it possible to transfer the two aircraft with the transfer number D-3 and D-6 via Vienna-Aspern to Belgrade at the beginning of 1932 . There they were, with their Wnr. 232 or 233 as service numbers, put into operation. It was not until 1937 that they were given different license plates with 172 and 173 respectively.

But in 1932 Dornier already had two more aircraft with the Wnr. 243 and 244 in progress, which may have already been ordered by Yugoslavia, but - under the current conditions - were no longer wanted by the client. These two machines, which clearly corresponded to the Do Y design, are listed as Do 15 in the company's list of serial numbers . The background to this was that the company had attempted to include these aircraft, which were already in an advanced state of construction, in the current tender of the Heereswaffenamt for the development of an alleged “ high-speed airliner ”, from which the Heinkel He 111 and the Junkers Ju 86 emerged a little later . The Dornier proposal Do 15, in which Lufthansa and Roluf Lucht (Dipl.-Ing. In the Heereswaffenamt, later chief engineer in the Technical Office of the Reich Aviation Ministry ) were already named as recipients , was understandably rejected, so that the company decided on these two Aircraft stuck again. Instead, however, with a fundamentally new design, the Do 17 , it was able to get back into the race for the first fighter aircraft types for the Air Force, which was already under construction .

The other two Do Y's were now called that again, although some significant changes had been made, such as the use of more powerful engines, but also a reduction in the wingspan. However, they were no longer completed in Manzell, but now in the Swiss plant in Altenrhein at the local AG for Dornier aircraft . The Yugoslav Air Force was interested in them again. Probably because of the scope of the work carried out on the two aircraft at the new location, they now also received new serial numbers, namely 555 and 556. After their completion (but not until 1936), the two aircraft with the Swiss transfer numbers HB-GOE and GOF - were transferred again Vienna-Aspern - delivered to Yugoslavia on March 22, 1937. All four machines remained in operation there until 1940. In that year they were also given camouflage for the first time and the new service numbers 3221 to 3224. When the German troops marched in in 1941, they were all found on the Kraljewo airfield , with the propellers removed and the engines covered. However, they were not scrapped as completely out of date, but went to the newly formed Croatian Air Force, which probably operated them until 1943. One of them served in the open, as a "decoy" for American hunters who are said to have made extensive use of it and thereby kept away from other targets.

Technical specifications

Colored side view

	Wnr. 232/233	Wnr. 555/556
Dimensions
span	28.0 m	26.5 m
length	18.2 m	18.2 m
height	6.8 m	7.3 m
Wing area	111.0 m²	108.8 m²
Crowds
Empty mass	5180 kg
Preparation mass	5530 kg
Max. Takeoff mass	8500 kg
Services
Top speed	244 km / h	300 km / h
Cruising speed	210 km / h	240 km / h
Summit height	5200 m	8000 m
Climbing time to 4000 m	27.8 min	14.3 min
Range	1100 km	1400 km
Engines
Type	3 × Bristol Jupiter VI	3 × Gnôme-Rhône 9Kers
High performance	510 hp / 376 kW	625 PS / 462 kW
Continuous output	360 PS / 265 kW	440 hp / 325 kW

See also

• List of aircraft types

literature

• Dornier Foundation for Aviation and Space Travel (ed.): Dornier: Factory history and aircraft types . Delius Klasing, Bielefeld 2009, ISBN 978-3-7688-2610-5 .
• Short story of Do Y by Dir. Eugen Jäger, Dornier, now EADS archive
• Test reports flight test Dornier, Altenrhein
• Letter to the editor Günther Ott, Jet & Prop 2/03

Web links

Commons : Dornier Do Y  - collection of images, videos and audio files

• Photos and data on histaviation.com , accessed July 1, 2013

Individual evidence

1. ↑ Heinz J.Nowarra: The German air armament 1933-1945. Bernard & Graefe Verlag, Koblenz 1993, ISBN 3-7637-5464-4 .
2. ↑ Airplane Classic Spezial 4 from Geramond Verlag, Munich 2009.