ARNOLD AIR FORCE BASE, Tenn. -- For nearly 60 years, a highly skilled workforce at Arnold Engineering Development Center's (AEDC) Model Shop has provided critical support to aerospace ground test, investment, plant and maintenance operations with precision machining, fabrication and product installment services.

One of the first buildings constructed after AEDC's dedication in 1951 was the "main" Model Shop. Consolidation took place 30 years later, bringing smaller groups of craft workers and their equipment from other shops on base to the Model Shop.

Currently, the Model Shop's workforce is busy employing capabilities provided by exponential advances in technology to meet the customer's challenging testing requirements in the face of emerging threats.

"The skills and machines in the shop generally support fabrication and modification efforts for our customers in plants and testing," said Walt Bishop, ATA test support branch manager, which includes manufacturing services or the Model Shop. "This includes large investment efforts like the 4T Captive Trajectory System (CTS) job in fabrication now to jobs requiring microscopes to work.

"The skill sets we have here are experienced and impressive, including highly skilled CNC [Computer Numerically Controlled machine] programmers, machinists, boilermakers, ironworkers, pipefitters, sheet metal workers and large cranes and riggers. With the experience and skills we have we can pretty much fabricate anything our customers want or find someone who can. Every day it amazes me to see what this shop can produce. I'm very proud to be a part of this workforce."

Bishop and Scott Henninger, manufacturing services manager in ATA's support branch, said the ongoing work at the Model Shop is dominantly large-scale fabrication, including model support systems, models, piping systems and plant facility equipment.

"Some of the more recent highly visible jobs we have fabricated include the Tunnel A return-to-service rebuild, 16T seal flap upgrade, the large B-52 model fabrication, and presently the 4T CTS effort," Bishop said. "And these are primarily only machinist efforts. We regularly have many large-scale jobs being worked simultaneously that may not have the visibility, but definitely require the same level of craftsmanship.

"Examples include the C2 test cell cooling piping effort, test stands, [Rocket Development Test Cell] J-6 diffuser relining and the ASTF exhaust side intercooler project."

John Wright is the ATA investment project manager for the CTS upgrade for 4T.

"The 4T Captive Trajectory Support (CTS) system is a computer-controlled six degree of freedom mechanical system used to investigate the separation characteristics of air- launched stores from parent test articles in [AEDC's] Aerodynamic Wind Tunnel 4T," he said. "It is the mechanism that permits acquisition of store separation data for the various aircraft/store combinations in the U.S. and allies' military inventory."

Wright had praise for the craft workforce handling the fabrication and machining of the components for the 4T CST upgrade.

"The Model Shop team's experience fabricating similar complex components has been invaluable to the success of the project," he said. "They have been able to review drawings and offer suggestions on ways to make fabrication more efficient and cost effective. The quality of their work is outstanding."

Wright added, "The new Tunnel 4T CTS will be able to carry higher loads, have increased six-degree-of-freedom travel range, more accurate model positioning, position faster, be calibrated much quicker and a much reduced maintenance requirement."

Peter Macaluso, AEDC's Air Force project manager for the wind tunnels, is the customer who tasked the Model Shop with modifying a 10 percent-scale BLU-109 Joint Direct Attack Munition (JDAM) model for a recent test in the Propulsion Wind Tunnel's 16T.

The test customers' requirement was for a one-time use of the model, but Macaluso said it could see future use.

"Our customer's needs change frequently and sometimes at short notice," he said. "For that purpose we maintain a large inventory of models, mostly at 5 and 10 percent scale which can be used in the 16T and 4T tunnels with a short lead time."

Macaluso is impressed with the Model Shop's expertise and way of conducting business.

"Their work is extremely professional, and the results show how much pride they take in what they do," he said. "The work they performed on the BLU-109 was adjusting the strakes on the side of the JDAM to match the current variant used in the USAF Fleet.

"These strakes are as thin as razor blades and the angle adjustment is critical. The Shop's precision was paramount to our success. Their capability is invaluable to us. Many of our projects require extreme precision. When preparing for a test we are glad to have confidence in a 'local' group who we can turn things over to with minimal oversight. When testing, the customer is paying over $1 per second for our services and when the customer's requirements change mid-test, we know we can count on the Model Shop getting results to us quickly."

Wright emphasized how important the Model Shop is in meeting the mission at AEDC.

"Approximately 80 percent of the tests conducted in Tunnel 4T investigate weapons separations," he said. "This improved capability will advance AEDC's ability to more precisely perform store separation tests and meet customer needs."

Paul Jalbert, an ATA aerodynamic project engineer, is overseeing a Compensated Hypersonic Instrumentation for Loads (CHIL) balance project.

"The objective of the CHIL balance project that is nearing completion is to develop a new, small, high-temperature capable balance that will enable store separation testing from aircraft models in high Mach number wind tunnels like Tunnels A and B in VKF," he said. "The CHIL Balance was successfully fabricated in the AEDC Model Shop, instrumented in the PWT Balance Laboratory, and is currently undergoing acceptance testing."

He said the effort involved around 20 people in AEDC's Model Shop to plan, machine and inspect the CHIL balance.

"Balance fabrication is difficult and requires lathes, mills, grinders, wire EDM (Electrical Discharge Machining) and die sinker machining," Jalbert said. "The CHIL balance fabrication was completed in only eight weeks. Following the precision inspection, rework on one non-compliant part was limited to 7 percent of the total effort."

A balance of this type presents challenges to everyone involved.

"The very small size of the CHIL balance and some of its calibration hardware presented a great challenge to the crew that did the machining, inspection and to the crew that installed the strain gage instrumentation," Jalbert said.

Jeff Quattlebaum, an ATA cooling water system engineer, tasked the Model Shop to fabricate and machine a steel pipe fitting called a 'tee' for the ASTF Cooling Towers.

"The tee is a steel pipe fitting, connecting three 72-inch diameter pipes at a perpendicular intersection," he said. "The tee is important because it is in the 72-inch discharge pipe leaving the cooling towers going to the plants and test cells.

"Without it the cooling towers are not usable. When the cooling towers are running at full capacity, about 205,000 gallons per minute of water pass through the tee on the way to the equipment in the plants and test cells that are being cooled."

Quattlebaum said the tee was fabricated to replace the one installed as part of the construction of the ASTF Plant and Test Cells in the early 1980's.

"The welds on the tee had deteriorated from corrosion and cracked," he said. "This crack caused a significant leak - the pipe contains 100 psi water. This section of the system, including the ASTF Cooling Tower, had to be shutdown in the fall of 2011."

With the new tee fabricated and welded into the system, the excavation site is currently being backfilled while utilities are reinstalled before power is restored to bring the towers back in service at the end of the month.

Boilermakers, pipefitters, and sheet metal workers contributed to the project.

"The team effort and workmanship provided by the Model Shop was excellent," Quattlebaum said. "The fabrication of the replacement tee was one of the first big efforts in the critical path of getting the ASTF Cooling Towers back in service. The quick turn-a-round they provided in building the tee set the tone for the rest of the effort."

The smallest fabrication and machining jobs require a microscope to complete. John Adams, an ATA machinist/welder at AEDC's Model Shop, is the craftsman who does this scale of work.

"I do all the welding for the machinists - everything from the micro-welding with a laser to rotary tube welding to large frames and structures like thrust stands and thrust stand adapters," he said. "I recently welded some data probes with our laser welder. I use the laser welder to weld small or delicate parts. I am certified in many different processes on many different materials. I also do various types of soldering."

Adams added, "We are very proud of our work and capabilities."

For John England, working at the Model shop is more than a job; it literally translates to family ties.

"My dad worked for the center contractor who poured and finished the floors here in the early 1950s," said England, ATA's boilermaker working foremen at the Model Shop. "I've counted 16 boilermakers, our supervisor and one planner - that brings 298 years of AEDC's service time and experience to the table. We have the expertise to do the unique work that the Model Shop does for AEDC and their capabilities are increasing as we add new machines and training to our employees."