Skiing is like flying – bear with me, this really is about your skiing. The F22 can only fly because laminar flow technology was developed sufficiently that it provided enough air resistance for the aircraft to push against.
Round about 350 BC, Aristotle thought that a flying object such as an arrow, was sustained in its flight by the air pushing it along, through the action of rushing in behind it to fill a vacuum. His idea assumed that air sustained its flight, rather than acting to retard it.
If he had been correct, skiing would not have been possible. Like the F22, you need resistance too. Understanding this could help your skiing enormously. Read on below the fold
It was not until the 15th century, that Aristotle’s idea was stood on it head. Leonardo da Vinci realised that air was a resisting medium. Without this conception, aerodynamic theory would be impossible.
In the early 1800s Sir George Cayley conjectured that sustained flight of a heavier than air object was only possible through the application of power, via a surface, to the resistance of the air.
Skiing: Enter Galileo
Galileo, born just over a century after Leonardo, identified the key fact that resistance (of the air) increased directly proportionately with velocity. Finally, Sir Isaac Newton through his creation of the calculus, gave the study of fluid mechanics the tool without which further development would have been impossible.
We now know that the characteristics of flying alter with altitude. The reason is that the air is thinner the higher the altitude. Therefore, so is the amount of resistance it offers. With less resistance, flying becomes less easy, and to sustain it you must apply more power. It is more difficult to fly at low speeds at higher altitudes: while higher speeds push the surface harder at the air, and satisfy Galileo’s proportionate resistance observation.
So, in brief, in order to fly your surface must find resistance. I have highlighted these three words because they are crucial to understanding why flying is possible. They are also crucial to
understanding why skiing can be done.
Snow as a fluid.
Fluids come in various forms: gaseous, such as air; highly viscous fluids such as tar or syrup; mobile liquids such as water; and other subdivisions. However, we shall consider another medium which is very variable – snow!
Now to skiing – Resistance is not futile! Many recreational skiers seem to have the idea, that half the problem with skiing is that it happens on an inclined surface which has no friction. This is correct as far as it goes; the surface of the snow has not quite none, but very little friction.
But you would be wrong to think this means there can be no resistance to progress. Wrong to imagine that like Aristotle’s arrow, you will not only never to cease to slip, but increasingly be likely to approach some wildly dangerous terminal velocity.
That’s why skiing can seem so fraught with potential for loss of control. Yet uncontrolled descents are very seldom seen. Even the most rudimentarily technically equipped skiers find some way of effecting control over their direction and speed.
This is because the snow offers us the opportunity to find resistance. Just as the resistance of the air makes flying an F22 possible. The resistance of the snow, makes skiing possible – and it is the only thing that does! Finding that resistance is key to finding and exercising control; indeed it is the sine qua non without which skiing could not be done.
You can find much more on this and other topics, plus things to do in my book at this link https://www.amazon.co.uk/Ski-Control-piste-anywhere-control/dp/1999901916/
If it doesn’t work just search Amazon.co.uk/books for Ski In Control: Bob Trueman.
Your skiing, powered by your lift pass.
Just as in the case of Cayley’s accurate, and hugely advanced conjecture about flying,you have to apply power to a surface acting on the fluid. In our case the fluid is snow – the surface is the sole of our ski. You must apply power to that surface to make it work. We skiers buy all the power we need, to power a week’s skiing, for a few £100s. it’s a lift pass. The lift pass – powering your week.
Gravity powers our skiing, through the medium of potential and kinetic
energy, which comes from the lifts raising us to higher altitudes. This power would be fruitless, if the medium (the fluid) with which we play, could offer no resistance. We would simply slip downwards out of control.
That is only possible, if we lose the resistance we need, just as an aircraft spirals downwards to crash if it’s control surfaces are compromised. Try to fly in space in an ordinary aircraft and the exercise will fail because there would be no resistance.
Resistance – the key to control
We all enjoy skiing most when we know we have control; we enjoy it least when we fear that we may lose control. To having control you need the technical ability to
obtain resistance from the snow; when you want it, how you want it, and for how long you want it.
Very good skiers revere “spring skiing”, because when you know how, you can keep moving round the mountain finding perfect snow on every run. They also revere it because it is never the same for two hours running, or sometimes two quarters of an hour in sequence. In
the early morning the snow is hard and icy because it melted yesterday, got a film of water on it, and then froze overnight.
By mid morning it’s just about right, just what the piste basher driver wanted. But by lunchtime the piste is a mush, liquid water in some spots, and slush elsewhere. So in the early morning, finding resistance is difficult because your skis tend to slip over the top which is very hard. Mid-morning, your skis cut-in just right and the snow offers just the right “feel”, just the right amount of “give-versus-grip”
Come lunchtime your skis don’t just cut-in they sink-in, and even then the stuff they’re in offers less resistance, it’s almost like water skiing. You can’t water ski very slowly. These conditions perfectly exemplify the way in which snow varies, and you can easily appreciate, that different techniques will be needed for each variation, but all with the same objective – find resistance!
© 2018 Bob Valentine Trueman All rights reserved.