No one can tell me Nobody knows
Where the wind comes from Where the wind goes
Wait, what? A good pilot knows where the wind comes from. Always! Otherwise he’s going
to end up stuffed in the wrong end of a windsock. Let’s talk about this folks, this is fundamental
to flight.
Of course you want the wind to be coming straight
up on the slope you’re going to be flying on. Everybody knows that. It’s simple with
a windsock. Just pop it up, and you get a good idea of what the wind direction is doing.
If you move slowly so that you get to the point that you can see down the windsock,
you are looking straight into wind. Hiya! Guys are having fun.
But what if you don’t have a windsock? Can you tell what way the wind is blowing?
Of course you can; very easy. If you just turn your head. Now I’m turning it off to the
side – and I’m turning it to the other side – I can hear the wind noise in my ears.
And when I can hear wind noise in both ears at the same volume I’m looking straight
into wind. So, I’ll prove that to you.
Wind direction
is there! Am I right? Course I am! So you can tell where the wind is blowing.
Once you’ve established that line, you know that the wind in this whole area
is going to be blowing in the same direction. The wind can’t be coming from over there
and over there at the same time. It’s all going to line up. If you imagine it’s like
a river and everything is moving the way I’m walking now. So the wind on that side and
the wind on that side, everything is coming in straight lines onto this ridge. So that’s
pretty simple. Everybody gets that idea don’t they?
You know that. I know that. Is it really the same in the air? And how can you tell what
the wind direction is, when you’re flying. Let’s go up and have a look.
OK, so you know how this trick works: I’m pointing straight into wind now, because I’m
looking straight down the windsock. But what’s happening down there? You see the windsock?
Which way is the wind blowing? So the wind is blowing this way for me here. Hang on a
minute! What’s going on there? Maybe if I slow down it will help. Nope, still
pointing into wind. That’s odd. Let’s do a turn. Hang on a minute, now the wind’s
coming from this side! And look at the windsock down there. The wind’s from there. No it’s
from here. No it’s from there. Hang on a minute. What’s going on there?
So of course when you’re flying the paraglider through the air you will feel a wind in your
face because you’re moving through the air. You will always be pointing into wind, the
relative wind. So your wing will always be flying forwards, your pod is kind of at right
angles to your wing, hopefully, so your feet will be pointing out straight into wind all
the time. If you’re not feeling this wind coming straight into your face, you need to
put your hands up because you’re stalling your wing.
It should be flying round about 40 kilometres an hour, between 30 and 40 depending on your
brake input. But you can see, I’m always pointing into wind. But the real wind, is
blowing from the side, over there. Now to be able to be going along this ridge I can’t
fly straight along it because that wind will push me over, so you can see I’m sitting
at a slight angle, and that angle changes depending on how strong the wind is. If the
wind is really strong, I’m going to have to sit pointing out to sea much more.
Now something’s happening, I’ve got a bit higher, now I’m doing exactly the same
pass as I was doing before, what’s happened? Well the wind must have got stronger. If you
look at the windsock down there, it’s a little stiffer, and that’s giving me more
lift, so immediately I know the wind’s increasing, the wind direction has stayed the same, the
wind speed has increased a bit. And I can tell how strong the wind is by how
much I’m angling off the ridge to keep a straight line. And if you find you’re angling
more off the ridge, the wind has increased. Right, so now I’ve settled into a nice straight
soaring line, I’m not doing anything on the brakes, and you can see, I want to fly
there, but I’m pointing there, which means the wind is coming from the left, and somewhere
in between the two I’ve found a balance point.
As the wind increases, I’m going to have to turn more out, and I’m going to go up.
As the wind drops, I’m going to be lower and needing to fly more along the cliff line.
I better have this right or I’m going to end up in the sea. Now if the wind was really
blowing from over there, there would be no lift along this ridge, the wind would just
be blowing along and it would be full of turbulence. Obviously it’s not blowing that way, because
look, it can’t be blowing that way and be blowing this way at the same time. So this
windsock has nothing to do with the airflow over the landscape. This is my little windsock,
and I’m causing this wind. Now the way to get higher on this ridge is
to find the piece of ridge where the wind is getting scooped up the most, and it will
usually be perpendicular to the wind direction. So I’m moving through the air here at 37
kilometres an hour, forwards, and that one over there is blowing about 20. If I turn
this way, the speeds are combined: you can see I come past really quickly.
So you’ve got to be really careful of going downwind towards the ground. So now you can
see the wind has dropped, because I’m lower, and I’m having to point more along the cliff
to keep my line. I’m just moving out now because there’s a pilot approaching. I’m
giving him lots of space so I don’t wake him on the ridge.
Then I can come back in again. But you can see the wind is a bit lighter because now
I’ve got a straighter line. I’m not having to angle out so much so the wind isn’t pushing
me so much. It’s getting lighter now: I’ve got to
be more careful now that I hug the ridge. Try and use the last little bit of lift here.
There’s a nice bit of lift in that bowl. Now he’s turning there, so I’m going to
use this opportunity to come in and use this bit of lift here. Now this bowl is working
better because the wind is coming in more right angles to the ridge, which gives me
more boost. Don’t worry if this concept is doing your
head in, it does everyone’s head in at the beginning, because you think you’ve got
it, and then you realise you haven’t got it. The relative airspeed, the ‘wind of
the paraglider’, and the real wind that you are flying through: the combination of
those two gives you your track over the ground. Once you’ve been flying for a little bit,
you also start building up a feeling for how fast you’re going over the ground, and what’s
normal. So just by looking over the edge here and watching my shadow going over the ground,
I can tell I am going slightly downwind. I’m used to my speed and that’s a little bit
more than my trim speed. So I know the wind is coming in from behind me.
And that’s very useful when you’re coming in to land and you’re trying to work out
which way the wind is. It’s just that appreciation of your speed over the ground. If it looks
scary fast on the ground, you’re going downwind. If it looks comfy cosy, you can put your feet
down, you’re pointing into wind. So now, comparing that shadow speed, I’m now pointing
into wind. And that’s a more acceptable landing speed
for me, that I’d be happy running the speed off.
So we’re coming up to approaching the windsock again. Just look at that. My wind, and the
real wind. Now what’s important, is where does the
wind come from?
It’s only now that these two windsocks are
going to match, when I’m stationary on the ground.
Otherwise, this windsock, the white one, is totally independent to the red one.
I hope that gives you a clearer idea of the difference between your airspeed and the real
wind that’s on the ground. Your airspeed is going to create a relative wind, you’re
going to feel that all the time, it’s always blowing straight at your nose, if it’s not,
you’re doing something wrong with your wing. It doesn’t matter whether you’re pointing
downwind, upwind, crosswind, sidewind, your ground speed is just going to change, you
won’t feel it. You can’t feel the difference when you swing around and turn into wind.
So try and remember that those two things are separate, your airspeed, and the wind
on the ground, and when you combine the two vectors, you get a resultant vector which
is your speed over the ground, and that will be affected depending on which way you’re
pointing. But you won’t feel any difference. So I hope that helps you clear up one of the
very difficult concepts in flying. And if you’re flying, and you’ve been flying
away and you don’t know what the wind is doing, fly in one direction, look at your
ground speed, and do a 90 degree turn, and as soon as you do the 90 degree turn you’ll
be able to see which way you’re drifting, and that will tell you which way the wind
is coming from. From that you turn into wind, you can see where your ground speed is slowest,
and that’s when you know you’re pointing directly into wind, and that will help you
with your landing setup. Where does the wind come from?
Every good pilot knows.
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What do you think about air speed, ground speed and wind speed?
Got any questions? Pop them in the comments below. Cheers!