Flying in a wind tunnel and freefall from an airplane both create the same aerodynamic effect – the wind pushing against you at terminal velocity can be utilized to move around.
Your body is made up of a bunch of different flat surfaces that all work in the same way – if the wind hits a surface head-on then the surface will be pushed directly in the other direction, and if the wind hits a surface at an angle then it will be deflected away at an angle. Think about how when you put your hand out of a car window on the highway and by altering the position of your fingers you can feel the air flowing over your digits and pushing things around. If you flatten out your hand and present your palm against the wind you will feel more resistance, if you make fist your hand has a smaller area to push against the wind you will feel less resistance. This is basically how everything works – in a tunnel, the wind is coming from below and going upwards. If you make yourself bigger more air will push against you and you will go up if you make yourself smaller less air can push against you and you will go down.
As a beginner you are taught moves that apply your body basically like one big surface – deflect air away behind you by straightening your legs and you to go forwards, deflect air away in front of you by straightening your arms to go backward. To go down you arch your body which makes your profile smaller and allows the air to slip off to the sides and to go up you simply flatten out a bit, just like your palm against the wind.
Things get progressively more complex from here as you introduce new moves and ways to fly. The key to mastering bodyflight is learning how to use all your individual surfaces then understanding how they apply together – sometimes they are neutral, sometimes they work with each other and sometimes they work against each other.
An important thing to remember is that all the complicated stuff is built from simple pieces you learn right from the start. When you first visit the tunnel and see people who are very practiced, it seems like they have magical powers as they zip and zoom with incredible precision and awareness. The road to awesomeness and success is built from simple puzzle pieces that are put together in different orders and combinations – and while the fancy moves are aerodynamically complex – they are created from very straightforward parts.
Jumpsuits can be really fancy, but they all work in the same basic way. Baggy suits grab the air creating more drag which makes you go slow. Skinny suits grab less air creating less drag which makes you go fast. In the most general terms – little people need less drag and tighter suits to go fast and keep up with the big people, while big people need baggier suits and more drag to ‘stay up’ (go slower) with the smaller people. Ideally, everyone meets in the middle.
As your tunnel flying progresses your ability to use your body develops and your range increases – you will need to rely less on extra fabric for help and will want gradually skinnier suits. There is no rush to get something skin tight as it does make training more demanding – but the overall philosophy is that the closer a suit is to the actual shape of your body, the better your physical understanding of how everything works aerodynamically around you.
As a beginner skydiving and tunnel flying look and feel the same, but the further you progress the more you realize the differences between the two environments. Flying in an indoor skydiving facility allows you to examine your skills under a microscope and push things to a level you never thought possible.
Wind tunnel flying has now evolved from what was once a novelty experience into a fully-fledged sport in its own right – with some of the best flyers in the world flying exclusively indoors. Getting really good is a demanding but hugely rewarding process, but right from the very start flying about using only your body feels like nothing else on earth.