G-force, jerk, and a giant centrifuge

Tom Scottcentrifugeg-forceRoyal Air ForceRAFaviation medicinephysicsaccelerationG-LOCsciencehuman enduranceQinetiQ

Tom Scott visits the Royal Air Force's training centrifuge at Farnborough to experience high G-forces. Experts explain the history of G-force research, including the harrowing rocket sled tests of the 1950s, and the physiological effects of extreme acceleration on the human body. After being briefed on anti-G straining maneuvers, Tom undergoes a simulated flight profile, ultimately experiencing a G-force induced loss of consciousness (G-LOC) before recovering.

Transcription

This is the Royal Air Force training centrifuge at Farnborough. And the team here are going to push me as far as they are allowed to push a civilian. The centrifuge has been here since 1955. The device was originally installed for research purposes although these days it's used for training as as much as it is for research. And what it does is recreate the forces that you feel in an aircraft. For our routine pilot training, the first time pilots go on the centrifuge, we expect them to get up to 5G without a G-suit and then up to 7G with an anti-G-suit. Now, I'm not taking a significant risk here. I'm healthy, I've pulled a few Gs before, and the human body can take this. And the reason we know that is because in the 1950s, the US Air Force used rocket sleds to push volunteers to incredible speeds. But that rocket-powered acceleration wasn't the dangerous or even the really high-G part of the test. See, high-G acceleration takes a lot of incredibly expensive rockets or a big old centrifuge like this. But high-G deceleration, all you need for that is a wall. Or for something less destructive, like the rocket sleds, you use scoops dropped down into a water trough. US Air Force flight surgeon John Stapp, aboard the rocket sled Sonic Wind number one, holds the record for the highest sustained G-force anyone has ever voluntarily endured: 25G for 1.1 seconds with a brief peak over 46G. And he was badly injured, but he survived and he recovered and he lived to the age of 89. The human body is an incredible thing, particularly because we didn't evolve for this. G-tolerance is something that's innate in all of us. Some of us have high G-tolerance, some of us have low G-tolerance. Over the years, people's G-tolerance doesn't really adapt. Any shortfall in G-tolerance has really got to be made up by physical exertion in the G-straining maneuver. What this centrifuge doesn't have is much jerk. And jerk is a technical term. In the same way that acceleration is the rate of change of speed, jerk is the rate of change of acceleration. And because it takes time to spin up and spin down... oh, here we go... even though the acceleration is high, the jerk here is relatively low, about 1G per second. Jerk is the difference between a rocket to space, which might take a couple of minutes to reach peak acceleration, and a fighter jet, where maneuvers might change the G-force acting on you in a fraction of a second. And it can go further than that. You can measure the rate of change of jerk, which is called snap or jounce. The two derivatives after that are called crackle and pop, but they're not all that useful in the real world. As we increase the G that Tom is exposed to, the blood's going to be pushed down into his feet and he's going to have to work really hard to push that blood back up to feed oxygen to his brain to keep him conscious. And in real life, we would be expecting that person to be flying an aircraft whilst doing that. I'm getting a little bit of grey-out. I can't quite see. We teach the anti-G straining maneuver, which composes of two separate parts. First of all, muscle tensing, so both the buttocks and the legs, squeezing the blood vessels to try and get the blood back up into the chest and the head. But also the second part is a breathing maneuver which increases the strain in the chest, directly increasing the blood pressure to the great vessels in the chest and keeping him conscious. And when you lose blood pressure to your head, you could even lose consciousness, and we term that G-induced loss of consciousness, or G-LOC. Blimey. I lost everything there. Wow. G-LOC in itself is not dangerous, but the real point is when you G-LOC, you're flying an aircraft. So if you're not able to fly that aircraft, I'm sure you can appreciate that that is a real problem. Because of John Stapp and all the volunteers like him that rode the rocket sleds, there is a lot of research into acceleration on the human body. How many Gs can be withstood for minutes at a time? How many Gs can be withstood for brief moments? And how many can be withstood with training that I clearly don't have. Rocket scientists and roller coaster designers use that data, but there's not much research into jerk, because how would you test it without also testing acceleration? Over on the Starship channel, I am not passing out pulling Gs with the Blades aerobatic team. And as for this video, thank you so much to all the team at the RAF Centre of Aviation Medicine, to the team at QinetiQ, and to the team at Starship.

Visual Timeline

0:00
medium shot eye-level Informative and anticipatory.

A man stands in a large room and gestures towards a massive, grey, lattice-like metal structure.

"This is the Royal Air Force training centrifuge at Farnborough. And the team here are going to push me as far as they are allowed to push a civilian."

Setting: Royal Air Force training facility, Farnborough — bright, even, fluorescent overhead lighting

People (1):

• standing, facing camera, wearing light grey hoodie over a red t-shirt and dark blue jeans, blond, medium length hair — smiling, speaking

human centrifuge arm (grey)
Colors:light grey, dark grey, beige, dark blue, red
0:07
medium close-up eye-level Authoritative and professional.

A man in a military uniform is speaking directly to the camera.

"The centrifuge has been here since 1955. The device was originally installed for research purposes although these days it's used for training as as much as it is for research."

Setting: Workshop within the training facility — soft, diffused lighting

People (1):

• sitting, wearing light blue Royal Air Force short-sleeve uniform shirt, short, brown hair — neutral expression, speaking

industrial equipment (red)

Text: "Wing Commander Nic Green", "Consultant in Aviation Medicine"

Colors:light blue, grey, brown, red, black
0:22
close-up on the cockpit low angle, looking up Calm, preparatory.

A man in a flight suit sits inside the centrifuge's cockpit as it remains stationary.

"For our routine pilot training, the first time pilots go on the centrifuge, we expect them to get up to 5G without a G-suit and then up to 7G with an anti-G-suit."

Setting: Inside the centrifuge gondola — bright interior light from above

People (1):

• sitting, strapped into a seat, wearing olive green flight suit and olive green flight suit, short, dark hair — looking up, calm

cockpit interior (black)
Colors:olive green, grey, black, tan, white
0:39
medium shot eye-level Historical, serious, tense.

Several men in vintage clothing adjust a helmet and suit on a man sitting in an open-air test vehicle.

"And the reason we know that is because in the 1950s, the US Air Force used rocket sleds to push volunteers to incredible speeds."

Setting: Archival footage of a US Air Force test site — harsh, natural sunlight

People (1):

• standing around a seated man, wearing jackets and coats and trousers — concentrated expressions

helmet (white)

Text: "Space Age Railroad (1969)", "USAF / Public domain"

Colors:white, black, grey, tan, dark green
0:55
medium shot eye-level Explanatory.

Tom Scott gestures with his hands while talking, then points towards the centrifuge.

"of incredibly expensive rockets or a big old centrifuge like this."

Setting: Royal Air Force training facility, Farnborough — bright, even, fluorescent overhead lighting

People (1):

• standing, wearing light grey hoodie and dark blue jeans, blond, medium length hair — animated, speaking

centrifuge arm (grey)
Colors:light grey, dark grey, beige, dark blue, red
1:48
medium shot low angle Active, demonstrative.

Tom Scott climbs up the metal lattice structure of the centrifuge arm.

"US Air Force flight surgeon John Stapp, aboard the rocket sled Sonic Wind number one,"

Setting: On the centrifuge arm — bright, even lighting

People (1):

• climbing, moving from right to left, wearing light grey hoodie and dark blue jeans, blond hair — concentrated

centrifuge arm structure (grey)
Colors:grey, dark blue, beige, black, red
2:00
close-up eye-level Sobering, documenting injury.

A man in a helmet and neck brace is attended to by others. He appears dazed and possibly injured, with visible bruising or blood on his face.

"And he was badly injured, but he survived and he recovered and he lived to the age of 89."

Setting: Archival footage of a US Air Force test site — natural, outdoor light

People (1):

• sitting, being tended to, wearing dark jacket, dark, visible under helmet hair — bruised, swollen eyes, dazed expression

helmet (white)neck brace (white)

Text: "Space Age Railroad (1969)", "USAF / Public domain"

Colors:black, white, grey, dark red, skin tones
2:13
medium shot eye-level Transitional, moving into the experiment phase.

Tom Scott enters the centrifuge gondola.

"G-tolerance is something that's innate in all of us. Some of us have high G-tolerance, some of us have low G-tolerance."

Setting: At the centrifuge gondola — bright, even lighting

People (1):

• stepping into the cockpit, wearing light grey hoodie and dark blue jeans, blond hair — neutral expression

gondola/cockpit (black)
Colors:grey, black, olive green, beige, dark blue
2:26
close-up point-of-view, from a camera mounted in the cockpit Informative, calm before the storm.

Tom Scott sits strapped into the centrifuge cockpit, looking at the camera mounted in front of him.

"What this centrifuge doesn't have is much jerk."

Setting: Inside the centrifuge gondola — bright light from above

People (1):

• sitting upright in a seat, wearing light grey hoodie, blond hair — calm, speaking to camera

safety harness (tan)

Text: "g 1.0", "jerk 0.0g/s"

Colors:dark grey, light grey, olive green, tan, black
3:20
medium shot low angle, looking up Action beginning, building intensity.

The centrifuge gondola, seen from the outside, begins to swing outwards as the arm starts to rotate and pick up speed.

"oh, here we go..."

Setting: Royal Air Force training facility, Farnborough — bright, fluorescent

centrifuge gondola (black)

Text: "g 1.2", "jerk 0.4g/s"

Colors:grey, black, white, red, beige
3:24
close-up point-of-view, from a camera mounted in the cockpit Strained, intense.

Inside the cockpit, Tom Scott's face begins to show the strain of the G-forces, his cheeks pulling down slightly.

"even though the acceleration is high, the jerk here is relatively low, about 1G per second."

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting, pressed back into his seat, wearing light grey hoodie, blond hair — strained, cheeks pulled down, still speaking

Text: "g 2.0", "jerk 0.0g/s"

Colors:dark grey, light grey, olive green, tan, black
3:48
medium close-up eye-level Expert, clinical.

A woman in a flight suit speaks to the camera, gesturing with her hands to explain a concept.

"As we increase the G that Tom is exposed to, the blood's going to be pushed down into his feet and he's going to have to work really hard to push that blood back up to feed oxygen to his brain to keep him conscious."

Setting: Control or equipment room — soft, even lighting

People (1):

• sitting, wearing olive green flight suit over a purple t-shirt, brown, tied back hair — serious, speaking

panel with pressure gauges (silver)

Text: "Squadron Leader Bonnie Posselt", "Registrar in Aviation and Space Medicine"

Colors:olive green, grey, silver, blue, purple
4:04
close-up point-of-view, from a camera mounted in the cockpit Playful but extremely strained.

Inside the cockpit, Tom Scott smiles and raises his hands, palms open, as the G-force increases. His face is heavily distorted by the force.

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting, being subjected to high G-force, wearing light grey hoodie, blond hair — grinning, cheeks and jowls pulled down significantly

Text: "g 3.6", "jerk 0.0g/s"

Colors:dark grey, light grey, olive green, tan, skin tones
4:08
close-up point-of-view Alarming, physiological distress.

Tom Scott lowers his hands and speaks with difficulty, his vision beginning to fade.

"I'm getting a little bit of grey-out. I can't quite see."

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting, experiencing grey-out, wearing light grey hoodie, blond hair — strained, mouth open, speaking with effort

Text: "g 3.6", "jerk 0.0g/s"

Colors:dark grey, light grey, olive green, tan, skin tones
4:12
medium close-up eye-level Educational, clinical.

Squadron Leader Bonnie Posselt continues her explanation.

"We teach the anti-G straining maneuver, which composes of two separate parts."

Setting: Control or equipment room — soft, even lighting

People (1):

• sitting, wearing olive green flight suit, brown, tied back hair — speaking clearly

panel with pressure gauges (silver)
Colors:olive green, grey, silver, blue, purple
5:15
close-up point-of-view Extreme physical exertion.

Inside the cockpit, Tom Scott's head is tilted back and his eyes are closed as he strains against the G-force.

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting, head tilted back, wearing light grey hoodie, blond hair — tense, eyes closed, mouth slightly open, straining

Text: "g 3.5", "jerk 0.4g/s"

Colors:dark grey, light grey, olive green, tan, skin tones
5:25
close-up point-of-view Intense, struggling.

Tom Scott performs the anti-G straining maneuver, making loud, sharp exhalations while tensing his muscles. His face is red and contorted with effort.

"(Straining noises)"

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting, actively straining, wearing light grey hoodie, blond hair — red, contorted, mouth open in a grimace, exhaling forcefully

Text: "g 3.6", "jerk 0.0g/s"

Colors:dark grey, light grey, red, tan, skin tones
5:32
close-up point-of-view Shocking, clinical.

Tom Scott suddenly goes limp, his head slumping forward and to the side. He has lost consciousness.

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• slumped forward in his seat, wearing light grey hoodie, blond hair — slack, unconscious

Text: "g 2.3", "jerk -1.4g/s"

Colors:dark grey, light grey, tan, skin tones
5:37
close-up point-of-view Disoriented, recovering.

Tom Scott's head lifts up suddenly as he regains consciousness. He looks around, dazed and confused, his eyes blinking rapidly.

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting up, looking around, wearing light grey hoodie, blond hair — confused, dazed, blinking

Text: "g 1.0", "jerk 0.0g/s"

Colors:dark grey, light grey, tan, skin tones
5:43
close-up point-of-view Surprised, incredulous.

Having recovered, Tom Scott expresses his shock and amazement at having lost consciousness.

"Blimey. I lost everything there. Wow."

Setting: Inside the centrifuge gondola — bright interior light

People (1):

• sitting upright, wearing light grey hoodie, blond hair — wide-eyed, surprised expression, speaking

Colors:dark grey, light grey, tan, skin tones
5:59
medium shot eye-level Reflective, post-experience.

Tom Scott is now out of the gondola and sitting on its edge, talking to the camera while regaining his composure.

"Because of John Stapp and all the volunteers like him that rode the rocket sleds, there is a lot of research into acceleration on the human body."

Setting: At the centrifuge gondola — bright, even lighting

People (1):

• sitting on the edge of the cockpit, wearing light grey hoodie and dark blue jeans, blond, slightly disheveled hair — smiling slightly, looks a bit tired

gondola/cockpit (black)
Colors:grey, black, olive green, dark blue, skin tones
7:07
wide shot eye-level Informative, concluding.

Tom Scott stands in the main room again, delivering his outro and pointing off-camera.

"Over on the Starship channel, I am not passing out pulling Gs with the Blades aerobatic team."

Setting: Royal Air Force training facility, Farnborough — bright, even lighting

People (1):

• standing, wearing light grey hoodie and dark blue jeans, blond hair — smiling, speaking

centrifuge (grey)

Text: "BUILT FOR SCIENCE", "tomscott.com @tomscott /tomscott tomscottgo"

Colors:beige, grey, light grey, dark blue, red