DI Proprotor Test Rig SOW DRAFT.pdf

Statement of Work

Proprotor Test Rig for Dynamic Interface Wind Tunnel Test

1.0 INTRODUCTION

The goal of the Office of Naval Research (ONR) Dynamic Interface Virtual Environment (DIVE) program is to reduce the at-sea flight testing needed to establish and expand rotorcraft launch and recovery envelopes through a more effective and efficient hybrid process employing modeling and simulation (M&S). The determination of whether the DIVE M&S process is “fit for purpose” requires truth data at the model subsystem and integrated simulation levels. A critical M&S element in need of validation is the CFD modeling of the aerodynamic interactions between the rotor, ship structure, and ship airwake. A wind tunnel test is planned in the NASA LaRC 14 x 22 wind tunnel to address this validation data gap. The test will be conducted at 1/8 scale with a single isolated Mach-scaled proprotor operating in the wake of an appropriately scaled air-capable ship model. A suitable proprotor test rig and rotor are required.

In 2015, ONR awarded the University of Maryland (UMD) Alfred Gessow Rotorcraft Center (AGRC) a Defense University Research Instrumentation Program (DURIP) grant to develop a proprotor test rig to carry out basic research on tiltrotor whirl-flutter stability in the Glenn L. Martin wind tunnel. The resulting rig, known as the Maryland Tiltrotor Rig (MTR), supports Mach-scale testing of 3-bladed, 4.75 ft. diameter proprotors on a gimballed hub representative of a 0.19 scale XV-15 or 1/8 scale V-22 tiltrotor. Although the MTR was designed for the lower rotor speed, thrust, and power required regime of airplane mode operation, the designers had the foresight to design the MTR control system, hub, and blades for the full envelope of tiltrotor operation. The MTR, therefore, provides a logical point of departure for the design of a proprotor test rig for the DI wind tunnel test that will reduce program risk, schedule, and cost.

2.0 SCOPE

This Statement of Work (SOW) is for a new proprotor test rig and supporting equipment collectively designated as the Dynamic Interface Proprotor Test Rig (DIPTR). The design of the MTR will be leveraged and modified as necessary for the DIPTR. Design of the MTR drive system, balance, rotor hub components and blades will be reanalyzed for the DI test design loads and operating conditions and scaled or redesigned as required. The existing selection of swashplate actuators will be evaluated to the new requirements and upgraded as required. A mounting interface between the rotor pylon and wind tunnel sting accommodating manual nacelle tilt will be designed and fabricated. A rotor control console to operate the test rig shall be designed, fabricated, and documented. Tests shall be performed to validate the operation of all of the rig's systems and functions. The proprotor test rig, control console, accessories, and associated drawings, data, and test reports shall be delivered to the Government.

3.0 CONTRACT TASKS

The contractor shall furnish the necessary personnel, services, materials, equipment, and facilities required to perform the following tasks.

3.1 Design

3.1.1 Conceptual Design

The Contractor shall develop design specifications and a conceptual design for the DIPTR to conform with the requirements specified in Section 4.0.

3.1.2 Preliminary and Detail Design

The Contractor shall perform the preliminary and detail design for the DIPTR based on the results of Task 3.1.1.

3.2 Fabrication and Assembly

The Contractor shall fabricate and assemble the DIPTR designed under Task 3.1.2.

3.3 Acceptance Test

The Contractor shall conduct a no load, full speed functional checkout of the test rig to check kinematic system clearance and instrumentation functionality prior to delivery to

NAVAIR.

3.4 Functional Test

The Contractor shall perform a checkout of the rig under full hover loading prior to the dynamic interaction wind tunnel test. This checkout may be performed at the 14 x 22 tunnel test cell or another appropriate facility.

3.5 Delivery

The Contractor shall deliver the DIPTR to NAVAIR no later than September 5, 2021.

Delivery dates for the other deliverables are specified in Section 8.

4.0 PROPROTOR TEST RIG REQUIREMENTS

4.1 General

This proposal is for a proprotor test rig and supporting equipment. The rotor parameters will based on a 0.125 geometric scale of a V-22 tiltrotor right-hand proprotor (counterclockwise rotation when viewed from above). A maximum rotor speed of 3300 rpm for the sub-scale system is required to match the hover tip Mach number of the full-scale system; the maximum power required is 90 Hp. The test rig includes a gimballed rotor head, swashplate, actuators, 6 component balance, motor, instrumentation, slip ring, nacelle, and sting mount. The effort includes design and structural analysis, part manufacturing and procurement, instrumentation application and rig assembly.

4.2 Proprotor Blades

The blade geometry will be provided by NAVAIR and is nominally the same as a scaled V-22 right-hand proprotor blade. The required rotor radius is 2.375 feet. Nominal targets for blade structural and mass properties will be supplied by NAVAIR. The blades will be instrumented for root flap-wise and chord-wise bending and torsion.

4.3 Rotor Hub

The MTR has a 3-bladed gimballed hub with a universal joint in lieu of a constant velocity joint for simplicity, with zero undersling, 2° precone, no torque offset, and zero gimbal spring constant by design, and a pitch-flap coupling of -15° at zero degree collective pitch. The rotor hub design shall be re-analyzed for DI operating conditions.

4.4 Rotor Pylon

The MTR rotor pylon is comprised of an in-line arrangement of the electric motor, a 6-axis load cell, and a 64-channel slip ring encased in a fiberglass fairing with their necessary adapters. In order to simulate a V-22 landing on a deck, the DIPTR rotor plane will come within 31 inches of the ship model deck, so the test rig pylon (nacelle) length must fall within this constraint. It is also desired to limit the pylon diameter to 20% of rotor diameter, therefore, 11.43 inches.

4.5 Sting Mount

A mounting adaptor shall be included to attach the test rig in a hover orientation (vertical) to a LaRC 14 x 22 sting. Model support interface details will be provided by the government. The mount will allow manual adjustment of pylon tilt angle in 5 degree intervals.

4.6 Drive System

The MTR drive system was designed for airplane mode operation and supplies the rotor with a maximum of 20 Hp at 2660 rpm. The DIPTR drive system shall be designed for VTOL operation and provide a maximum of 90 Hp at 3300 rpm.

4.7 Balance

The DIPTR shall have a 6 component force and moment balance sized for a maximum steady hover thrust load of 300 lb. Steady and oscillatory unsteady design limit loads will be provided by NAVAIR.

4.8 Instrumentation

MTR instrumentation includes a 64-channel slip ring, a 6-component load cell, a shaft torque transducer, and tri-axial accelerometers on the pylon for vibration. Rotating frame measurements include all blade pitch angles, two gimbal tilt angles (for the gimballed hub), three pitch link loads, and rotor speed and position, with another six channels dedicated to blade structural loads for safety-of-flight.

4.9 Control System

The MTS features a conventional swashplate providing +/- 10° of cyclic pitch and a collective range from -10 to 28° driven by high bandwidth linear actuators. During DI testing, harmonic input from these actuators will be used to control rotor flapping (gimbal motion) during operation in the unsteady ship airwake environment (see next section). Control system deliverables shall include:

a. Control hardware to enable functional checkout including a motor control, actuator servo amplifiers, actuator control, a programmable logic controller (PLC), electronics rack, and cables from rig to electronics rack.

b. Additional control hardware to enable full power and fully controlled testing including computers, monitors, cables from rack to computer.

c. Control programs for full testing. This effort includes writing of programs, checkout and user manuals.

4.10 Closed Loop Flap Controller

A high bandwidth closed-loop flapping (gimbal motion) controller. The controller algorithm will be supplied by NAVAIR but the equipment needed for implementation – high bandwidth electric actuators – are part of the procurement. This is an essential element for rotor testing in turbulent ship airwake.

4.11 Control Console

The rotor control console shall be designed to provide blade pitch control inputs to the DIPTR control/actuator system and allow monitoring of critical DIPTR system health and rotor operating parameters. The console shall be designed such that the primary set-up, calibration, control, and display functions are under microprocessor control. This makes the console design adaptable and allows straightforward control-mode changes during testing. Redundant, fail-safe logic shall be employed and redundant hardware shall be utilized where appropriate. To the maximum extent possible, the console design should allow for future upgrades/changes. This include the planned addition of dynamic actuator control for swashplate actuators.

4.12 Model Disposition, Storage, and Documentation

The model shall be the property of NAVAIR following completion of testing. This includes all test hardware and instrumentation either procured or designed and fabricated specifically for the model, including spare parts and accessories. A model storage box facilitating access, storage, and transportation of the model to and from test facilities shall be provided. Storage for additional parts and hardware shall be provided, either with the model or in a separate box/container as appropriate. Documentation of the model supporting hardware, including inventory and specific instructions for use, storage, and transportation shall be provided IAW A004

5.0 SCHEDULING

Period of performance is from 1 June 2020 through 30 Sep 2021.

6.0 GOVERNMENT FURNISHED EQUIPMENT (GFE)/GOVERNMENT FURNISHED

INFORMATION (GFI)

Electronic CAD data files defining proprotor blade geometry

Nominal blade structural and mass properties

LaRC model support system interface specifications for sting mount

Rotor operating steady state and oscillatory load limits

Closed-loop flapping control algorithm

7.0 DOCUMENTATION

7.1 Conceptual Design Report

The Contractor shall submit to the Government a Conceptual Design Report documenting the design specifications and the conceptual design (A001). This report shall be submitted at least one week prior to the Conceptual Design Review.

7.2 Preliminary Design Report

The Contractor shall submit to the Government a Preliminary Design Report documenting the design specifications and the preliminary design (A002). It shall also include the proposed workmanship and inspection plan to be followed during fabrication. This report shall be submitted at least one week prior to the Preliminary Design Review.

7.3 Design and Analysis Report

The design and operation of the proprotor test rig shall be described in the Design Analysis Report (DAR) (A003). This report shall contain as-built design drawings (both mechanical and electrical) as well as other associated design documentation.

Manufacturers' documentation for all processors, subsystems, and operating systems shall also be included in these documents. A failure modes analysis of the rotor control console will be performed and the results reported in the DAR. The DAR shall also describe standard operational procedures as well as provisions for setup, checkout, and calibration of the test rig. A draft of the Design Analysis Report shall be delivered to NAVAIR two weeks prior to the Critical Design Review (CDR). The final version shall be delivered to NAVAIR with the test rig.

8.0 REVIEWS

Three design review meetings shall be required. A Conceptual Design review meeting, a Preliminary Design Review (PDR), and Critical Design Review (CDR) meeting shall each be conducted at NASA Langley Research Center. Additionally, periodic telephone contacts and site visits at contractor facilities shall be conducted by NAVAIR personnel to monitor technical, cost, and schedule status.

9.0 CONTRACT DATA REQUIREMENTS LIST

CDRL Sub Title CDRL

SOW

Para

Submittal Dates

Conceptual Design Report A001 7.1 1 week prior to the Conceptual Design Review

Preliminary Design Report A002 7.2 1 week prior to the Preliminary Design Review

Design and Analysis Report A003 7.3 2 weeks prior to the Critical Design Review

DI Proprotor Test Rig and Parts Documentation Report

A004 4.12 30 days after model completion