Arnold Engineering Development Center

How Lost Core Resin Transfer Molding Revolutionized Air Force Test Center Transonic Wind Tunnel Blades

Overview

Arnold Engineering Development Center (AEDC), part of the U.S. Air Force Test Center (AFTC), 704th Test Group, operates the 16T Transonic Wind Tunnel at Arnold Air Force Base, Tennessee. Its mission-critical aerodynamic test conditions of Mach 0.05 to 1.60 have supported every major Department of Defense and government flight vehicle test program over the past 55 years.

Customer's Challenge

By 2018, the 1960s-era 16T-C1 fiberglass composite wind tunnel blades had endured many years of harsh operating conditions and had exceeded their useful lifespan. As part of a facility upgrade program, replacement blades were required to sustain operation and enhance the 16T Wind Tunnel capabilities.
The 30-foot diameter 16T rotor utilizes 97 blades in three stages, operates at 600 RPM, in excess of 1500G, and is powered by a 400,000 HP electric motor drive system. Each legacy fiberglass composite blade weighs 113 lbs.

Replacement blades had to be reverse-engineered from 1960s-era blueprints and surviving legacy blades, operate in minus 20 to +320F wet conditions, and retain visual transparency for in-service visual inspections.

Fiber Dynamic's Solution

The FDI team won the preliminary design contract in 2019 and successfully developed and characterized the composite materials, completed the reverse engineering and geometric verification, and reconfigured the assembly to address known durability and maintenance issues.

We ensured the design’s robust capabilities by performing static and dynamic structural FEA analysis, ballistic testing, damage simulation, and developed impact repair methods.

Customer's Results

The re-designed blades achieved a 15% weight reduction and met all design requirements, including the capability to increase HP capacity by 30% for future applications.

FDI produced ten prototype blades utilizing the Lost Core Resin Transfer Molding (LCRTM) process, developed and matured by FDI experts in previous work. Hollow internal cavities, integrated longitudinal spars, and co-molded steel mounting bushings were all made possible with a very innovative processing solution.

FDI teamed with NIAR-Wichita State University to conduct full-scale structural testing, including tension and combined bending conditions at maximum operating temperature of 320F and required factor of safety. The new fiberglass composite blades met all design requirements and FDI was contracted for blade production.

A full tunnel set of 97 blades was completed, installed, and placed into service in Q3 2024.

A complete spare set of 97 blades is scheduled for FDI production in 2025-2026.

To date, blades have been proven to be of exceptional quality…FDI’s transparency and forthrightness is greatly appreciated. Immediate notification of technical and programmatic issues – along with full disclosure of causes and options have resulted in rapid resolution and has created a high level of trust and respect.

AFTC Administration

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