The Air Force is in the testing phase of a centrifuge for gravity training and research at the 711th Human Performance Wing on Wright-Patterson Air Force Base.
At the base where G-force training and research has been conducted since the dawn of the jet age, this new centrifuge replaces several others in the Department of Defense, including one that is already mothballed in Building 33.
Maintaining fighter pilot G-tolerance is a critical part of flight physiology as the performance of the latest generation of fighter aircraft become more demanding of the pilots.
So what is G-force? The term “G” comes from the force of gravity. As we stand on Earth, we experience one G. Fighter pilots experience this to the extreme while maneuvering, particularly in tight turns where the pilot may experience 9 Gs. That would make 180-pound pilots feel like they weighs 1,620-pounds.
This is where the trainer comes in. When extreme pressure is experienced, the blood in the pilot’s body wants to flow downward away from the brain, causing potential loss of consciousness. By practicing a G-straining maneuver in the centrifuge, pilots learn how to counteract the blood pooling G-force by tightening and flexing muscles in the legs, butt and abdomen to keep more blood in the brain.
“So that’s our number one priority for this device is training. And it’s a very specific breathing pattern the pilots have to do,” says Scott Fleming, Program Manager, 711th Human Performance Wing, School of Aerospace Medicine.
“That’s why this is such an important device. We can do that stuff here on the ground without doing that up in the air and subjecting the loss of an aircraft or pilot. And this is a safe environment. We can stop this thing in less than three seconds.”
How does it work? To achieve this kind of G-force on the ground, a cockpit enclosed in an egg-shaped pod is swung in a circle on the end of an arm which is attached to a very large motor, creating centrifugal force. If you were to swing a water-filled bucket in the same manner, centrifugal force would keep the water in the bucket. This is the same force that creates the Gs in the centrifuge.
The base continues to test human limits. G-training is not new at Wright-Patt, but this centrifuge offers research capabilities that older models don’t. This machine can reach 20Gs, including up to 15 Gs in just one second.
“It’s a very quick onset rate. We use mannequins for that type of testing,” said Fleming. “For humans we usually train up to 9 Gs with a 6 G-per-second onset rate.”
Major, major heft. To make a device like this operate safely and efficiently, the centrifuge side of the building was, essentially, built around the electric motor that runs the unit. A hole, 50 feet in diameter and 35 feet deep was created for the centrifuge. Structural concrete was poured to form the motor pit, base and walls.
“A thousand cubic yards of concrete were poured,” Fleming said.
The electric direct-drive motor weighs 240,000 pounds and swings the arm and cockpit that weigh more than 30,000 pounds. Bolts that are 14 feet long were used to secure the motor to the concrete.