FS98 Otto C.I twin-boom pusher Biplane, 1916
============================================ Stephan Scholz, September 2008

INSTALLATION
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Unzip Otto_CIu.zip into a temporary directory and copy the directory "Otto_CI" into the main FS98 aircraft directory.

Note: This version corrects previous scale error in overall length and landing-gear width.
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Otto C.I History
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In 1911, Gustav Otto, the son of the inventor of the four-stroke internal combustion engine, with his partner Dr. Alberti, opened the firm Flugmaschinenwerke Gustav Otto in Munich, and in 1912, he opened a branch firm in Berlin-Johannisthal, named AGO Flugzeugwerke (Aerowerke Gustav Otto).

With a layout similar to that of the contemporary Voisin and Farman biplanes, i.e. with strutted fuselage ("Gitterrumpf"), a boat-shaped central gondola and a "T" tail, his chief constructor Gabriel Letsch developed the Otto Doppeldecker pusher biplane, powered by an AGO (Aviatiker Gustav Otto) 100 hp engine of their own construction. The aircraft was produced in small numbers, becoming popular as a trainer.

At the beginning of WWI, AGO tried to obtain wartime contracts for reconnaissance aircraft, and
one of the models produced was the Otto C.I pusher biplane. The strutted rear fuselage of previous Otto Doppeldecker was substituted by two sturdy, hollow, twin tail-booms of rectangular cross-section, holding one-piece twin fin/rudders and the tailplane with its elevator. The booms were fixed to the wing-struts on either side of the central gondola, where crew and pusher-engine were housed. Engine-radiators were mounted on both sides of the gondola, which was a plywood covered wooden structure of rectangular cross-section, rounded above, and which had a machine gun fixed to the nose. Wings and tailplane were of fabric-covered wooden structure. The aircraft had a four-wheeled undercarriage, and brakes were a metal hook or spike mechanism, which the pilot dug into the ground after touchdown.

Very little additional information is available, but given its great similarity in size and shape to the AGO C.I pusher biplane, it most probably had the same motorization,i.e. a Benz Bz.III or a Mercedes D.III engine. A less powerful one such as a 120hp Argus AsII engine would have made the aircraft quite underpowered and unfit for military service. Consequently, the Otto C.I was presumably similar to the AGO C.I in performance. These models were reputed as being manoueverable, reliable, and easy to handle, both on the ground and in the air.

Wingspalette.com has one colour side-view of a tan-coloured Otto C.I, with the comment that it was in service at Udovo airfield in 1916 with Serial Number C.3575_15.

Furthermore, Earlyaviator.com has a front-view photograph of the Otto C.I, showing that although equipped with tail-skids, it was not a tail-dragger.

Specifications:
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Armed reconnaissance biplane, with twin tail booms and a pusher engine.

Crew: two, pilot and observer
Length: 9.0 m (29 ft 6 in)
Wingspan: 15.0 m (49 ft 2 in)
Wing area: 41.5 m² (447 ft²)
Powerplant: 1x150 Hp Benz Bz.III combat-rated at 165 hp
Maximum speed: 140 km/h (75 kt)
Range: 480 km (260 nm)
Service ceiling: 4,800 m (16,000 ft)
Armament: 1×7.92 mm Parabellum machine gun

The Virtual model:
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Built with Abacus Aircraft Factory 99, and animated with Abacus Aircraft Animator (ailerons, prop, elevator and rudders).
Pictoric information for this project was scarce, and limited basically to only two sources: Wingspallet.com and Earlyaviator.com, who had a colour side-view and a frontal photograph respectively.
Parts count is at an appreciable 131.3%, and there is surprisingly little bleedthrough.
The lights ("L") key will make the pilot and observer/gunner appear, and the spoiler key ("ç") will deploy the spike between the main wheels, and dig it into the ground to act as a brake. Note that you will still need to press the brake key (".") to slow down the plane.

Flight Dynamics:
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These originally came from Christoph Ruhtenberg´s FD for the Gotha G.I Ursinus, but have been modified considerably to fit the specifications and performance envelope of this aircraft.
Flying this aircaft is easy, as commented in the historical texts, and its behaviour is quite stable and nimble, with a good rate of climb.
Take off with neutral trim, under full power, and rotate at 38-41 Kt. Landing approach should be at 45-50 kt with idling engine as need be, and touchdown at 40 kt. Careful: Avoid stall at 30 Kt.

Textures:
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These have been carefully re-worked by Udo Entenmann. To be noted is the shadow of the Maltese cross, visible on the underside of the top wing through the translucent canvas.
Crew´s head texture is modified from a bitmap originaly by A.F. Scrubb.
Wheel textures, come from Eric Johnson's FS5.1 Cessna 177B source files, in beige and re-shaped to cover two wheels.

Panel:
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Defaut Sopwith Camel panel.

Sounds:
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Default Extra300 sounds. The larger propeller diameter entry in the .air file and the lower rpm entry, make this sound rather adequate for the low rpm of the Benz Bz.III engine (max 1420!).

Legal stuff:
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This aircraft and panel are freeware, created solely for the enjoyment of the flight simming community. No responsibility is taken for any loss or damage incurred directly or indirectly from its use. The original unaltered files may be freely distributed, uploaded, downloaded and shared. Please maintain proper credit, of course, and make no financial gain whatsoever!

Enjoy it!

Stephan Scholz
[email protected] September 2008