Evening All,
Here are some more pictures of the completed model and some notes on the type. I apologise for the backgrounds but the weather and light are very poor at the moment. I will take more pictures in better light when I have completed the base for this model: this will be my next project. I did not know of this machine until I came across it by chance about 15 months ago. The build thread is in the scratch builds section of this site.
Claudius Dornier had joined the Luftschiffbau Zeppelin (Zeppelin Airship Works) in 1910 where he worked on a number of technical problems associated with airships. He was transferred to Zeppelin’s private design bureau in Friedrichshafen to work on an 80,000 cubic metre steel airship capable of flying across the Atlantic in 1913. Following the outbreak of European war in August 1914, Zeppelin established the VGO-Staaken venture to build giant wooden bombers, but Zeppelin was convinced that the future for aircraft was in all metal construction, so Dornier was sent to an old airship shed at Seems near Friederichshafen on Lake Constance to design a giant flying boat. This became known as the Rs I and was the first all-metal aircraft to be built. It was a huge biplane with a 143 ft (43.5m) wingspan which carried out extensive taxiing trials on the lake in late 1915 but was wrecked in a storm in December of that year before it could fly.
While the Rs I was undergoing trials, Dornier and his team were working on a second project which was of a totally different design. This had a very broad hull which gave it inherent stability, with a high mounted wing with a broad low aspect ratio, open tail boom and unusual biplane elevator. Small wings were fitted to the rear of the hull to support floats, but the latter were found to be unnecessary and were never fitted. It was built from duraluminium and steel and covered in sheet duraluminium on the hull and fabric on the flying surfaces. It was powered by three engines buried in the hull driving pusher propellors via drive shafts. It made its maiden flight from Lake Constance on 30 June 1916. In mid - July an accident occurred which caused the aircraft to land on the water. On attempting to take off the middle propellor transmission shaft broke which severely damaged the tail boom.
It was decided to completely rebuild the aircraft and work was completed in early November 1916. The hull was redesigned with the step moved further back but more importantly a fourth engine had been added and all had been moved to a position between the hull and the wing. They were mounted uncowled in tandem pairs and drove tractor and pusher propellors - a feature which was to be used by Dornier on his flying boats until 1945. The wing was lowered and balance horns were added to the ailerons. The massive V struts which supported the wing were altered so that they now attached to the hull sides and the boom attachment to the hull was changed so that the rear propellors had clearance. The biplane elevator was retained, but the stub wings were reshaped to have rounded tips and a decreased chord. Materials shortages and poor quality fuel retarded testing, with constant problems being experienced with the engines. The engines were found to be too cold so very neat cowlings were fitted, following which the radiators were found to be too small as the engines overheated. In May 1917 during landing practice, the machine came down hard on the water and the central boom of the tail broke. The pilot did not notice and tried to take foo, with the result that the sagging tail dragged the aircraft back on to the water and the whole unit broke away and sank to the bottom of the lake.
In July the machine reappeared with a new tail unit this time with a simpler pair of fins and rudders and single elevator. Flight trials resumed and it was shown that it could take off and climb on 3 engines. It was also found that the pusher engines were more efficient when working alone than were the tractor engines. It reached a level speed of 128kph over the lake. In August it was carrying out a 6 hour trial flight prior to being sent to Norderney seaplane base for trials by the Navy when number 4 engine backfired violently. No 1 propellor disintegrated as a consequence, so both engines were shut down and the aircraft was put back down on the lake. The damage was found to be extensive and is was decided that it would have been uneconomical to rebuild it as the Rs III was near completion. Instead the airframe was broken up and the parts used for further tests and experiments.
Dornier and his team learned many valuable lessons from this prototype. The broad inherently stable hull, tandem mounted engines, all-metal construction, high wing with low aspect ratio, all became characteristic features of later designs, but above all reliability and flexibility were to be hallmarks of the Dornier company.
Do you remember the Avro biplane that appeared in the build thread for scale? Well here it is next to the completed model:
And because you cannot see everything from a distance, here are some close ups:
A happy 2018 to one and all.
Thanks for looking.
Stephen.
