High-speed rotorcraft of the MI-450 family - A new generation of cross arrangement rotoray-wing aircraft

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Korotkevich, M.
Midzyanovskiy, S.
Ivchin, V.
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?h? paper presents the results of the studies carried out to validate the concept of ? new generation compound helicopter of cross arrangement (side-by-side rotor) configuration with the estimated cruise speed of 450 kmh, dubbed the Mi-450. The key features determining the Mi-450 rotorcraft family configuration are as follows: a new type rotor system which consists of two slowed during cruise mode rigid rotors accommodated overlapped on a short wing; a thrust propeller located above the fuselage on the fin; modular split torque rotor gearboxes having large-diameter shafts which house blade pitch fly-by-wire actuation devices; rotor blades with embedded in the roots hinges; a transport module which is a fixed wing aircraft type fuselage equipped with ? high energy absorbing landing gear and new generation on-board systems. The Mi-450 design and technology characteristics of rotor and transmission systems make it possible to eliminate the design limitations of the Ka-22 side-by-side compound helicopter which caused the helicopter crash and led to subsequent program closing; it is also possible to avoid significant weight increase inherent to single and coaxial rotor helicopters. The study shows that the Mi-450 compound helicopters require significantly less power to fly at 100 to 400 kmh as compared to conventional helicopters and tiltrotors. On the other hand the Mi-450 compound helicopters require more power for hovering and low-speed level flight than conventional helicopters and tiltrotors due to wing download and rotors interference. However, unlike tiltrotors the required power increase for these flight modes and decreasing autorotation performances are not that dramatic for the Mi-450 rotorcraft. The Mi-450 compound helicopters family transport efficiency is considerably higher than that of conventional helicopters and is close to tiltrotors by this criterion. The following are the main competitive advantages of the Mi-450 compound helicopters family as compared to tiltrotors: development, production, certification and operation cost reduction due to lighter and less complex construction. Also it provides a much safer flight because in case of engine failure it is possible to land safely on autorotation due to much lower disk loading, higher rotor inertia and lower rotor blade twist.