Chyetverikov ARK-3

The Chyetverikov ARK-3 (ARKtichyeskii - arctic) was an Arctic multi-role flying boat designed and built in the USSR from  featuring a conventional flying boat hull, with high cantilever wings equipped with floats at mid-span. The two engines were mounted in tractor-pusher fashion on a pylon above the fuselage.

Development
In 1933 Chyetverikov had the design for a compact twin engined flying-boat ready for further development, which he proposed to the Glavsyevmorput (Glavsyevmorput – chief administration of northern sea routes) as a multi-role Arctic aircraft, and an order for a prototype was made, setting up Chyetverikov in his own OKB.

The ARK-3 was of mixed construction with Duralumin stressed skin fuselage, wooden wings of MOS-27 aerofoil section with duralumin tubing tail surfaces and ailerons with fabric covering. The dual control enclosed cockpit housed two pilots sided by side with two gunners/observers in bow and dorsal positions. Strut supported wooden floats, at approximately half-span, and a pylon supported engine nacelle housing tandem radial engines with Tow,nend ring cowlings, completed the structural elements, built with a safety factor of 5.5.

Flight and sea trials in 1936 revealed weaknesses in the bows, floats and engine nacelle pylon, which were all strengthened, but performance was good, prompting an order for a second prototype which was designated ARK-3-2, and the first prototype was re-designated ARK-3-1. A production order for five aircraft was placed, with production commencing immediately.

On the 14th of July the ARK-3-1 was destroyed following a structural failure, the ARK-3-2 was destroyed exactly one year later and the programme was cancelled.

Variants

 * ARK-3-1 – The first prototype ARK-3 renamed after the second prototype was ordered
 * ARK-3-2 – The second prototype ARK-3 with more powerful engines, longer hull, increased wing chord and manual guns fitted in a manual gun turret in the bows and a dorsal sliding hatch.
 * ARK-3 MP2 – Designation of the five production aircraft and the initial designation of the first prototype.