Hessert machinists create precision parts for research
When air speeds inside a hypersonic wind tunnel are expected to reach 4,000 miles per hour, the crafting of the most critical part of the tunnel — its 25-foot, 5-ton stainless steel nozzle – needs to be hyper-exact.
So the aerospace engineers designing Notre Dame’s Mach 6 wind tunnel turned to their in-house experts at the machine shop in the basement of the Hessert Laboratory for Aerospace Research.
“There need to be 21 pieces that can fasten together because each piece needs to be hand polished to perfection to minimize friction,” said Gene Heyse, manager of the machine shop in the aerospace and mechanical engineering department. “It needs a 7 percent taper on the inside, and it has to be perfect to 1/10 of a thousandth of an inch. So we built our own gauge to measure it accurately.”
A tenth of a thousandth of an inch is 40 times smaller than the width of a human hair.
That kind of problem-solving and that level of precision are why professors and researchers across campus and beyond turn to the Hessert machine shop to build the devices they need for cutting-edge research.
As a Notre Dame core facility, the shop charges $59 per hour, less than outside companies that may charge $85 to $200 an hour. The machinists there regularly make complex propellers and foils for wind tunnel research, but their projects can range from mosquito experiments to dune buggy gear boxes.
In another case, the University power plant wanted to resurface a 1955 boiler door that had warped. Since no blueprint could be found, Heyse and his fellow machinists used a massive computer-controlled Hurco mill to figure out the contours and create a new blueprint.
“They said the screws were going to cost $1,200 each to buy,” said Mike Sanders, another machinist. “We made them for $500 total and they bought us pizza.”
Heyse, Sanders and Terry Jacobsen were all born in South Bend and worked for years in local machine shops, including a dozen years together at the same place. They made parts for everything from power brake units in cars to aircraft fuel controls for Honeywell. It can take half a year to learn how to run the computerized mills and lathes that do the precision grinding and cutting — and longer to become expert at troubleshooting and special projects.
In other shops, Heyse said machinists get handed the specs and told to make a certain number of whichever widget is needed. The machinists get a paycheck but not much satisfaction.
“But here, there’s a lot of innovative ideas and testing,” he said. “The projects are often done to prove a theory rather than to make money for the boss. These brilliant professors know what they want to build, but they want our opinion on how to do it. It’s more of a partnership.”
Heyse, 60, who started at Hessert six years ago, so preferred the collaborative method of creation that he eventually lured his friend Jacobsen, 56, a year after he started and Sanders, 50, a year after that.
“I asked them, ‘How many shops have you worked at where people are happy, where it’s a community?’” Heyse said. “It makes you proud of what you’re making when you can help people try to get it right.”
Aerospace engineering professor Tom Juliano worked with Boeing to design a one-of-a-kind nozzle for a Mach 6 wind tunnel at Notre Dame. The stainless steel nozzle must be built in sections that fasten together so that the interior can be hand polished, and it must taper at 7 degrees with specifications within a tenth of a thousandth of an inch.
The machinists built the sections on a computer-controlled mill that uses carbide tools to cut metal. They experimented with different ways to connect the sections so that there is no seam to create turbulence. They also built their own bore gauge in order to precisely measure the nozzle’s taper at a 7-degree angle.
The machine shop is creating each piece separately so that it can be sent to a specialist for hand polishing and returned for assembly. The $4.7 million wind tunnel is scheduled to open in July 2018.
Falcon 10 Laser Communications
Aerospace engineer Eric Jumper wanted to measure airplane turbulence to keep it from interfering with his laser-based communication system. Using two Falcon 10 aircrafts, Jumper and the Aero-Optics Group have been developing laser connections that can create secure communications and guide weapons systems.
The machinists built a custom-designed piece that bolts onto the outside of the Falcon 10. A series of thin metal probes hold Tygon tubes with sensors that measure air pressure.
The custom-built piece allowed engineers to measure the turbulence and account for its interference with their laser-based communication system.
Baja Dune Buggy Parts
Student engineers entering an intercollegiate dune buggy competition needed custom parts for their vehicle. They could design the parts but needed help in making them work.
Machinist Mike Sanders helped them build a gearbox, bearing hubs and steering knuckles in his mill.
Sanders even used his mill to etch some inspiration onto the steering knuckles.
Mosquito Experiment Chamber
Biologist Nicole Achee and Neil Lobo won a $23 million Gates Foundation grant to study mosquito control in order to prevent malaria and dengue fever. They wanted to test how mosquitoes react to various repellants and attractants in combination and they needed a device that could test both at once.
The machinists built a tube with the mosquito chamber in the middle and space for attractants and repellants to be inserted on either side to see how the mosquitoes react.
The device was so useful that other universities, and even the U.S. Centers for Disease Control and Prevention, ordered copies.
Graduate student Mitsugu Hasegawa noted how smoothly seals and other aquatic mammals with hair sailed through water. He theorized that the hair follicles on the seal helped reduce drag and wondered if he could build something to mimic the hair follicles and reduce drag.
The machinists built an especially large airfoil in three perfectly aligned pieces so that Hasegawa could apply different thicknesses of a taped coating with imitation hair follicles.
Hasegawa and his colleagues have been testing different hair coatings on the air foil in wind tunnels at Notre Dame’s White Field Research Building.