Force and Moment Measurement Systems

Form / Attachment / Pricing Sheet

This document outlines the technical requirements for the procurement of a flush-mounted external panel balance for the AFRL-operated supersonic wind tunnel. It specifies the functional and performance requirements for this wall-mounted device, which is intended to measure loads on wall-mounted approximations of vehicle acreage panels.

• Scope: Covers functional and performance requirements including degrees of freedom, expected loads, operating environment, physical dimensions, mounting interfaces, data acquisition, and calibration.
• Functional Requirements: The balance must measure up to six components of aerodynamic forces and moments.
• Performance Requirements:
  • Degrees of Freedom: Single-component drag (Threshold), 6 forces/moments (Objective).
  • Expected Drag Load: Estimated range of 5-100N, with extremes of 0.145N and 300N.
  • Maximum Lift Load: Estimated instantaneous lift loads of 6.75lbf (Threshold) and 20.25lbf (Objective).
  • Operating Temperature Range: Less than 200°F.
  • Operating Pressure Range: Vacuum (<0.1 psia).
  • Duty Cycle: Test runs < 5 minutes, typically < 20 times per shift.
• Physical Requirements:
  • Dimensions: Must have a bolt pattern to mount Government-supplied 9" x 5" test articles.
  • Mounting Interface: Must sit flush with the tunnel floor, mounted within a Government-supplied Multi-bay Frame.
  • Alignment and Tolerances: Gaps/steps on wetted surfaces must be less than 0.005".
• Data Acquisition: Anticipated acquisition rates are < 200 Hz.
• Calibration Requirements: Performer to supply recommended calibration procedures, intervals, and as-built data sheets.

This document is critical for vendors to understand the specific technical specifications and performance criteria for the external panel balance. It details the expected loads, environmental conditions, physical constraints, and data acquisition needs, which are essential for designing and fabricating a compliant balance. Bidders should pay close attention to the stated requirements and the encouragement for early discussions regarding potential impacts of these requirements on the final product.

Statement of Work (SOW) / Performance Work Statement (PWS)

This document outlines the functional and performance requirements for a two degree-of-freedom (DOF) actuated model positioning system (MPS) and a Force & Moment (F&M) measurement system for the AFRL-operated supersonic wind tunnel.

• Procurement of a 2-DOF actuated model positioning system (pitch-roll or pitch-yaw).

• Procurement of a 6-DOF internal force and moment balance instrument.

• The MPS will provide precise control of test article orientation.

• The MPS will interface with contractor-supplied F&M balances.

• The document specifies required articulation range, control, interfaces, and critical parameters for the MPS.

• It also specifies expected operating environment and maximum load for the internal balances.

• Internal Balance Functional Requirements: Measure six components of aerodynamic forces and moments (Normal, Axial, Side forces; Pitching, Yawing, Rolling moments).

• Internal Balance Performance Requirements: Maximum aerodynamic loading is a critical design factor, with an estimated breakdown load formula provided (N = (17.3 lbf/in²) * S). Operating temperature range: 20-200°F. Operating pressure range: vacuum (~0.1 psia).

• Model Positioning System Functional Requirements: Provide precise control of model orientation (pitch-roll or pitch-yaw) with a minimum angle range of Pitch: -10° to +10°; Yaw: -5° to +5°. Seamless integration with F&M balances (mechanical, wiring, data handling).

• Model Positioning System Performance Requirements: Actuation rate > 0.5°/second. Angle accuracy < 0.1°. Control interface compatibility with existing facility data/control systems (NI LabVIEW-based) with closed-loop control and logged output.

• Data Handling: Synchronization/alignment of control and position feedback with F&M balances and other facility data systems. Time-synced output (NTP, PTP, IRIG-B) in a documented format.

• The MPS must mount via the facility's existing ceiling and floor modules (approx. 7 in wide by 35 inches long on the flow side).

• External space for mechanisms is limited to a cavity approx. 9.5 inches wide by 38 inches long.

• Mounting via the ceiling only is highly preferred.

• The primary test core is centered approximately 20 inches forward of the ceiling module's leading edge.

• Center of rotation for the pitch axis should ideally be near the upstream edge of the test area.

• Operating Duty Cycle: Intermittently operated blowdown facility. Test runs < 5 minutes, typically < 20 times per shift. Pre/post-operational procedures may require stagnant vacuum for longer periods (typ. 30 minutes).

• Balance Dimensions: Anticipated diameter 0.5” – 0.625” (open to revision).

• Mounting Interface: Cylindrical device, suitable for various test article geometries and adapters.

• Calibration: Recommended procedures and intervals to be supplied by the performer.

• Wiring: Routed through the actuated mechanism and terminated outside the test section.

• Handling: Integrated attachment points for overhead lifting.

• Test Area: Center of rotation configurable.

• Note: Figure 2 provides a notional concept for illustration only; the vendor-proposed solution is not required to implement this specific design.

Statement of Objectives (SOO)

To procure and integrate necessary systems and infrastructure for conducting Force & Moment (F&M) measurements in a wind tunnel at Arnold AFB, TN.

This effort requires three distinct F&M systems:

• System 1: A multi-degree-of-freedom actuated model positioning system (pitch-roll or pitch-yaw) with internal balance(s) for measuring forces/moments on freestream-mounted test articles. Vendors must address this system.
• System 2 (Optional): A "half-span" balance for measuring loads on test articles mounted to the test section floor or ceiling.
• System 3 (Optional): An external balance for measuring loads on acreage panels mounted flush to the tunnel floor.

Vendors are encouraged to address all three systems and leverage commonality.

The Statement of Work (SOW) will detail specific, performance-based tasks to satisfy technical requirements outlined in Attachments 2, 3, and 4.

Key planned events include:

• Project Kickoff Meeting
• Revision/Confirmation of Technical Requirements
• Conceptual Design Review
• Preliminary Design Review
• Authorization to begin procurement of long-lead items
• Critical Design Review
• Installation Plan
• Installation into wind tunnel
• Hardware Checkout for Full Functionality
• Training Plan

Tangible or intangible data items resulting from the work, including:

• Review Slides and Supporting Analyses
• Material Test Reports
• Inspection Reports
• As-Built Drawings
• Instrumentation and Wiring Diagrams
• Installation Plans
• Training Plans
• Software Documentation (including source code)

The Government will receive Unlimited Data Rights to all contractor-produced technical data and drawings.

Performer-developed, on-site system orientation/training for each delivered system is required. A Training Plan must be submitted for Government approval prior to delivery.

Development and maintenance of a QCP to ensure requirements are met and milestones are achieved. Procedures for corrective action are required.

Offerors have flexibility in managing schedule, performance, risks, warranties, subcontracts, and data, while maintaining clear Government visibility.

• Attachment 1: Technical Requirements: Actuated Model Positioning System and Internal Balances
• Attachment 2: Technical Requirements: External Balance for Fin Loads
• Attachment 3: Technical Requirements: External Panel Balance

Statement of Work (SOW) / Performance Work Statement (PWS)

This document outlines the requirements for procuring an externally mounted balance for measuring fin loads in AFRL-operated supersonic wind tunnels (tunnel 1 and tunnel 2).

• The balance must measure at least three components of aerodynamic forces and moments (lift, torque, and bending moment about the shaft).

• Key areas covered include degrees of freedom, expected loads, operating environment, physical dimensions, mounting interfaces, data acquisition, calibration, and articulation range and control.

• Requirements are specified as Thresholds (T) and Objectives (O).

• Maximum Lift Load: Estimated loads for tunnel 1 are 375 lbf (T) and for tunnel 2 are 1120 lbf (O), based on an estimated area of 21.7 in².

• Maximum Bending Moment: Approximately 1164 lbf-in (T) and 3468 lbf-in (O).

• Operating Temperature Range: 294 K (T); 611 K (O).

• Operating Pressure Range: Must operate at vacuum conditions (<0.1 psia).

• Operating Duty Cycle: Test runs are typically less than 5 minutes, occurring fewer than 20 times per shift. Pre/post-operational procedures may require stagnant vacuum for up to 30 minutes.

• Dimensions: Maximum balance diameter of 3.0" (T) or 1.5" (O). Torque tube diameter requirements are specified.

• Mounting Interface: Balance mounts to the test article, potentially partially within the test section or externally. Must operate at vacuum conditions (> 0.02 psia).

• Acquisition Rate: Anticipated rates are < 200 Hz for steady-state loads.

• Performer to supply recommended calibration procedures, intervals, and as-built data sheets.

• An integrated system to rotate the torque tube for fin angle of attack control is desired.

• Shall seamlessly integrate with the fin balance, including mechanical mounting, wiring, and data handling.

• Performance: Angle Accuracy <0.1°, Actuation Rate > 0.5°/second.

• Control Interface: Vendor to supply control software compatible with existing facility systems (NI LabVIEW-based).

• Data Handling: Synchronization/alignment of control and feedback with facility data systems; time-synced output (NTP, PTP, IRIG-B).

• Wiring: Routed through the actuated mechanism and terminated outside the test section.