How a glider works
One of the most common questions I get asked is when I land in a farmer’s field, which is a rare event but occasionally we do as pure glider pilots, is what happened, did the wind stop? That is the most commonly asked question. Gliders don’t just fall out of the sky and I would have landed in a field for a very good reason usually because the lift has stopped, rather than the wind. Gliders have a tear shaped wing like this, and as we’re flying through the air, as long as we’ve got speed the air flows over the wing and beneath the wing, and it creates lift. So we’re never going to fall out of the sky but we are in this constant descending pattern rather like a person on a bicycle, just simply gliding down a slope they stay on the same glide slope, slowly going down that hill. And we can go great distances, we can fly for hundreds of kilometres and the way we do that in the main is by using something called thermals. A thermal is when, on a beautiful day like today, the sun heats the ground and it creates a bubble of warm air on the ground. That bubble lifts off the ground and it rises. Warm air rises, we all know that. But what it also does, as that warm air rises it cools and condenses to form a cumulus cloud and we as glider pilots know that everywhere there is a cumulus cloud there’ll be some lift. So we fly towards a cumulus cloud and then we start turning and we rise up with that warm, rising air. We have an instrument in the cockpit that tells us whether we’re going up in the rising air or down in the sinking air. So, what we do is, we use those thermals effectively like filling stations. We fly to a thermal, we climb in that thermal and we descend as we go to the base of the next thermal and we climb up again and we go the base of the next thermal and climb up again. And by doing that, we can go some very great distances. Now some gliding clubs in the UK have ridges. This is Sutton Bank and it’s got a beautiful ridge here. When the wind is blowing against that ridge it blows against the ridge, up and over the ridge and down the other side. And what we do as glider pilots where the wind is blowing against the ridge it creates an area of lift, and we can fly in that lift not particularly high above the ridge but if that ridge is vey long, we can go quite some distance so it’s very good at Sutton Bank to do that. We beat up and down the ridge like that. We can be airborne for many, many hours doing that. And the third type of lift is what we call wave. Now this is when we get a particular wind blowing against the side of a mountain. So these are bigger areas of ground effectively, large mountains. Could be the Pennines, could be up in Scotland And this time we’ve got the wind blowing against the mountains. And it goes up, over the mountain and down on the descending side. But it does this through the atmosphere very high up into the atmosphere like this. Quite often, on the up-going part of the lift you’ll get a flat cloud called a lenticular cloud. And so we again as glider pilots know that’s a good area of lift. So, we’ll fly under that lenticular cloud and we’ll beat up and down that cloud. It’s totally different to thermals. It’s a very calm, still form of lift and you’ll be going up like you’re in a glass elevator going up and up and up, climbing and watching the altimeter climbing higher and higher and higher in the cockpit. On thermals, on an average day, we can climb up in a thermal and we can climb to something like four or five thousand feet or so and we would glide down to about two thousand feet. Either way wave lift or thermal lift, we can go some very big distances. When we fly cross country, the main aim is to fly around selected turning points. Those turning points might be a church or a motorway junction or a reservoir and the aim always is to get back to the home airfield. That’s really important to us because that completes the full task of what we were trying to do. On rare occasions we may have an instance whereby a weather front comes in and we no longer have this heating from the sun on the ground and therefore the thermals slowly but surely die out and for us that means the lift is no longer there. So eventually, if I’m half way around a task and there’s no other airfield nearby on that rare occasion I may need to choose a suitable field one without cattle, that I can land in. So it will be a nice grass field that I can approach and land safely in and not do any damage to the farmer’s field or to myself. So really that’s the basics of gliding and how we stay airborne. If you’ve got any interest now in gliding why not go along to your own gliding club and there’s plenty around near to where you live Go and talk to people there – they’re very friendly and you can go and have a trial flight and see what it’s like. I can promise you, when you have a trial flight you’ll thoroughly enjoy it. It’s so quiet and peaceful up there and if you want to maybe go on and have a flying career it’s a great opportunity to learn how to fly. It gives you the good grounding in the flying technique and basics before you move on to powered aircraft. So I thoroughly recommend it.