Feel the Force – Part 1
Do you ever get it into your head that a particular word or phrase seems wrong and you can’t rest until you know the answer? Now I’m not a stickler for the English language but one such phrase that I intrinsically dislike is “F1-pilot” and since I can be pedantic at times I had to find out whether I was right or wrong in my dislike of the term.
It turns out that “pilot” has many definitions including;
1. One who operates or is licensed to operate an aircraft in flight.
2. One who is licensed to conduct a ship into and out of port or through dangerous waters.
3. To steer or control the course of.
So I had been wrong, but it did set my mind wondering what the parallels were between an aircraft pilot (specifically a fighter or stunt aircraft pilot) and an F1 pilot; they’re both involved in steering complex equipment at extreme speed requiring quick reaction times, but both are also subject to large g-forces… I decided to explore the topic further.
So what exactly is g-force?
The simplest explanation is that “g” represents gravity whilst “force” is an acceleration. When you are sitting at home quietly reading you are subject to 1
Speed alone does not increase g, its forces like acceleration or breaking especially when coupled with a directional change that ramp up the intensity. You will have momentarily felt the effects of increased g if you have ever been on a rollercoaster ride or felt the acceleration as you take off on that holiday flight. But exposure to high g-forces especially when sustained for long periods can place extreme demands on the body.
This video of pilots undergoing training shows the acute effects of high g in the vertical (head to toe or “Gz”) direction; g-forces can also be front to back (transverse, Gx) or side to side (lateral Gy), the more likely directions of force felt by formula one drivers.
Effects of high g on fighter pilots
Straining exercises can help avert a loss of consciousness particularly when the forces are ramped up slowly, but when those forces are applied suddenly the effects can be devastating as the brain is deprived of blood, oxygen and glucose. So how does this come about? Normally, when you are lying down, your head is level with your heart and blood flow to your brain is maximised, when you sit or stand up your heart has to pump against gravity to push enough oxygen rich blood to your brain. You may have felt the light-headedness associated with postural hypotension if you have ever stood up very suddenly from a prone position and you felt dizzy.
As gravity increases it becomes more and more difficult for the heart to pump sufficient blood to the brain as the tendency is for blood to pool in your lower extremities. Fighter pilots can to some extent minimise the effects of high g- by use of straining exercises and by wearing a g-suit, a garment fitted with balloons which when inflated put pressure on the lower legs and help stop blood draining towards the legs. But even before the point where people lose consciousness (g-LOC, in the video) vision is affected. As g increases, both colour and peripheral vision are lost and it’s as though you are looking into a tunnel with restricted views either side, obviously this could be catastrophic for the person if they are also involved in some sort of extreme activity like flying or driving a formula one car.
Effects of high g on formula one drivers
Drivers are also subjected to high g (up to 5 g in a race situation), but rather than being in the vertical direction they are subjected to transverse and lateral forces which presents some different challenges to the body. This is nicely demonstrated in this video of Martin Brundle driving a Williams F1 car.
Transverse or lateral g places increased pressure on the parts of the body that supports the weight, with sideways forces in particular having an effect on the muscles that support the head and neck. It is for this reason that formula one drivers concentrate their training on strengthening their neck muscles and improving their cardiovascular fitness. But it’s not just stress on the neck and vision that’s affected, balance is too, with the vestibular system (inner ear) playing an important part in providing input to the brain, these signals result in spinal reflexes that brings about correctional changes to posture. Rapid changes in acceleration or direction can both confuse the system leading to confusion, dizziness and disorientation.
So how can drivers’ best adapt to the demands that increased g places on their bodies?
G-suits would be ineffectual in an F1 situation, the g is not sustained in any one orientation for long durations and the leg compression the suit maintains would be damaging for muscle control whilst driving. Instead, the most effective solution is exercise, upper-body strength is crucial as is cardiovascular fitness and strong neck muscles to support the weight of the head and helmet. For these reasons formula one drivers must be supremely fit to cope with the demands placed on their bodies.
The g-forces found during race conditions do not normally exceed 5g; however, during an accident they can be very much higher. Robert Kubica’s spectacular 230 km/h crash in Canada 2007 peaked at around 75g over one millisecond according to the official data released from the FIA, more on that in the next part of “Feel the Force”…