What is McCready's theory in paragliding?

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What is McCready's theory in paragliding?


If you've started to take an interest in the exciting world of paragliding, chances are you've ever heard of  McCready's theory and  you're not quite sure what it's talking about.

That's why in this article we've decided to delve into this theory and give you all the information you may need to further understand this theory.

What is McCready'stheory?

McCready's flight theory, as the name suggests, was made by  Mr. Paul  McCready, who was the man who managed to simplify calculations for paragliders and gliders using a graduated ring, which was placed on analog barometers, allowing the paraglider pilot to improve his flight speed in transition depending on the average value of the thermal.

That is, if in the day there was no lift, then the value of the thermals would be 0, setting the ring to 0 on the barometer. If the day had an average lift of 2, then the ring was rotated to +2 to match, being able to easily adjust to the value of the thermals.

What's McCready's theory for?

So that you can better understand how it works I will ask you to imagine three pilots who leave at the same time and at the same height a thermal to address another:

1. The first pilot flies using only the concept of constant speed, which would give a value of 0 calculated by  McCready.

2. The second pilot believes that the next thermal will have an average value at the time of starting to rotate it or during the entire ascent path of 2 m/s, so he adjusts his ring to 2 m/s, managing to fly at a value of 2 m/s (faster in speed than pilot 1). This will get faster to the next thermal compared to pilot 1, but it will do so much lower. However, when Pilot 1 reached the next thermal, Pilot 2 will already be higher because it will take time to remount it.

3. Pilot 3 believes it is best to fly much faster between thermals, ignoring any  McCready value, flying at a McCready value higher than the thermal value out there. This pilot will arrive before the other two, but he will do so being so down that, when Pilot 2 reaches higher, Pilot 3 will continue to try to go higher below.

The best of the three pilots will be the one who manages to better hit the value of the thermal and who knows how to paraglid at the best speed depending on his polar, always applying the McCready correction. The only thing McCready doesn't tell us is where the thermals are, where the best ones are, and how they should be focused.

The truth is that many people find this very simple, because on a theoretical level it is really simple, but the truth is that in practice this can be much more complicated than it seems. It should be noted that the low atmosphere is divided into different layers in which thermals have different thermals with different average ascent values.

Thus, if pilot 2 reaches the thermal before, but at a height where the slow thermal rises +1.5 m/s, but pilot 1 did not fly using any McCready, it will reach higher and is in a thermal of +4 (with an average of +2), then pilot 1 will have done better. While Pilot 3, who risked everything for higher speed, may be able to find a thermal fresh out of the ground so strong that he can make up for risking it.

That is, although you can talk about average thermals, it is very important to always take into account the fact that not all thermals have the same average, since not even the same thermal can maintain the same average always along its height. This means that the lucky factor will always be present.

However, applying the thermal along several paragliding flight thermals will always end up giving a great advantage to the pilot who better uses  McCready's theory. It should be noted that the average value is considered as the value that is at the time of entering the thermal. Throughout the flight this value may change repeatedly.

Thanks to its effectiveness, all experts agree that McCready's theory is above the  "Speed to Fly" concept, in which what is sought is to fly at the highest speed according to the polar. But it is considered that this should be the pilot's first challenge, and then focus on applying  McCready's theory.