The Model QH-50E

    When Boeing ceased building its 365 shp model 550-1 turbo-shaft engine (military designation T50-BO-12) in April 1968, Gyrodyne sought other engines to power its dynamic rotor system and provide the Navy the opportunity to not cancel the UAV program due to Boeing's exit. 

   What began as the Allison powered YQH-50E test vehicle, as seen left, became the QH-50E. The initial Allison T63-A-5A, Model 250-C19A, free turbine type, gas turbine engine used in the YQH-50E, was rated at 317 SHP at sea level, standard conditions. 

    The QH-50E was designed and fabricated under Naval Air Systems Command Contract No. N00019-69-C-0361 which was authorized by the United States Navy on December 31, 1968. 
    Although only three aircraft were delivered to NATC, Patuxent River, Md. for stability and control tests in 1969 under that contract, 3 subsequent QH-50D aircraft were later converted into E's by the installation of the Allison power package. The QH-50E is currently the final variant of the QH-50 series helicopter.

 
    As the QH-50E was produced in a limited amount, its U.S. Naval service history is limited to the testing of the engine combination only. Upon the engine qualification that the Navy accepted, all further QH-50 orders were cancelled in 1969 due to Navy down-sizing and the scrapping of many of the ships the QH-50 operated from.
     As the Allison powered QH-50E was seen then, as it is today, as the progenitor to expand the mission capabilities so adequately illustrated by the D model, we herein submit a detailed description of the E model to illustrate what an Allison powered QH-50 would look like. 

The Difference

    The only difference between the D and E model QH-50, consist of installing a new engine and engine attachment (see photo-above left), and altering the direction of flight, which is the reverse of the Model QH-50D in that the engine is installed aft of the rotor mast and the avionics equipment, flotation equipment and fuel tank are forward of the mast.

    Like the D model, the QH-50E rotor system is of the two-bladed coaxial semi-rigid type, incorporating fiberglass blades of a 2:1 taper ratio with a negative twist of 12 degrees. The Model QH-50E was designed like the D, to be capable of carrying and launching two (2) MK44 Torpedoes, or one MK46 Torpedo, or a special weapon payload of 1500 lbs.

The Fuselage 

    The lower casting of the transmission forms the main portion of the fuselage. Attached to the casting are the four supporting struts for the skid-type landing gear, the bomb shackle mechanisms, and two upper and two lower support tubes. The fuel tank is mounted on the lower two tubes of the forward truss assembly and is positioned directly ahead of the transmission casting. The tank is further secured by a forward panel and the upper two tubes of the forward truss assembly. This panel also serves as a mounting board for some components of the Automatic Stabilization and Remote Control Equipment (ASCE), as well as other equipment such as flotation gear and operational telemetry; see figure at right.

The Transmission

    The rotor transmission system consists of a two-stage gear reduction system, two rotor drive shafts, an integral lubricating system, a generator drive, and a four-axis servo actuator drive. Power from the engine is transmitted to the rotors through the two-stage gear reduction; the second stage of which divides the torque to the two contra- rotating coaxial rotor drive shafts. The generator drive and four-axis servo actuator drive are connected by gears to the outer (lower) rotor drive shaft.

The Rotor System

    Two 2-bladed semi-rigid contra-rotating coaxial rotors comprise the rotor system. The blades are of glass fiber reinforced plastic construction - incorporating linear taper in planform and thickness and 12 degrees negative twist. The Model QH-50E vehicle is completely controllable through the rotors. Rotor controls are operated by the Automatic Stabilization and Remote Control Equipment (ASCE). Control in pitch and roll is achieved through conventional cyclic control of the swash plates. Collective pitch control is obtained by conventional collective movement of the swash plates. Control in yaw is achieved by means of rotor blade tip-mounted air (drag) brakes. Movable tip brakes are located at the tips of both the upper and lower rotor blades and provide, by their deflection, positive directional control in all conditions of flight by creating an unequal torque distribution in the rotor system. A left turning moment results from lower rotor tip brake deflection while a right turning moment results from upper rotor tip brake deflection. In the neutral condition, both sets of tip brakes are undeflected.

Power Plant

    The power plant for the Model QH-50E vehicle is the T63-A-5A, Model 250-C19A, Allison gas turbine engine. The gas producer section is composed of a combination six-stage axial flow one-stage centrifugal flow compressor directly coupled to a two-stage gas producer turbine. The power turbine section is composed of a two-stage free turbine which is gas coupled to the gas producer turbine.  The engine incorporates an integral reduction gear box which provides an internal spline output drive at the front of the gear box. The power plant has a take-off power rating of 317 SHP at 6,000 rpm, at sea level standard conditions. The engine is attached rigidly, by means of a cast aluminum mount, to what is now the rear face of the transmission. This face was fwd and where the Boeing engine was mounted in the QH-50D. The engine intake is behind and below the transmission and faces forward and the engine exhaust is directed outward and downward. A transmission input power drive shaft connects the engine with the transmission first stage gear system and runs inside the engine mount.

    Today, there is only one QH-50E that survives of the three originally converted from D models; that being DS-1717 (see below for the fate of DS-1718 and DS-1719). DS-1717 resides in a storage building at White Sands Missile Range, New Mexico, parked among some 20 surviving QH-50D model aircraft requiring overhaul before flight.

     While DS-1717 sits among it brethren D models, its future is uncertain as its' uniqueness as a prototype invalidates its further use other than for parts for the D models currently flown for Army missions. The Gyrodyne Helicopter Historical Foundation is dedicated to the saving of this "one of a kind" aircraft so that future generations can see the combining of the QH-50 Co-Axial rotor system to the currently available Allison (now Rolls Royce) 250 series engine. Its use as an educational tool illustrating that engine-coaxial rotor combination, is incalculable. 

    Despite the QH-50E being a prototype aircraft, the increase in payload due to the lower weight Allison engine provides such increased benefits, that the information below is herein provided so that the performance criteria using the lower horse powered C-19 can be seen; Imagine if this aircraft had the use of the Allison 250-C20B (420 Shp).......

Helicopter Historical Foundation
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