The landing approach against a wind presents interesting problems especially for the model pilot who has no airspeed intruments.

Let's start by assuming a totally calm day. An aircraft only knows about the air it is in, nothing about the ground it is over. The pilot is concerned about ground position but the behaviour of the plane is purely aerodynamic and knows nothing about the ground. On a calm day the motion through the air equals the motion over the ground. For the sake of this example we will use the 3 degree approach favoured by full-size. Our plane is lined up and approaches the runway on a path that is inclined at 3 degrees down through the air, and therefore also 3 degrees over the ground. Ignoring the slight difference due to the angle of descent, one mile through the air equals one mile over the ground. Now introduce a headwind, straight down the runway. The descent angle through the air can no longer equal the descent angle over the ground, the air angle will be less than the ground angle.

You have only one choice in a glider, but two choices if flying power. The glider must make the same approach through the air at all times, so in a wind it must start its approach much closer than on a calm day. It still descends through the air at the same angle but when compared to the ground it is much steeper than a calm day. If you take it to the limit and the wind speed equals the glider's approach speed, the approach will be vertical compared to the ground, yet still the original angle through the air. Imagine the glider releases a smoke trail in finals, whether in wind or calm by the time it touches down both smoke trails will match one another because one will have been laid over the ground and the other will have been blown back over the ground. So when your model goes deadstick and becomes a glider, you must allow fo the wind by turning finals much closer and do not be fooled by the apparent steep descent angle and low forward speed over the runway. Look at the angle the fuselage is at - is it the same attitude i.e. nose up/level/down that you normally fly the approach in calm conditions? If you fly the same attitude as in calm weather then you have got the same airspeed, ignore the groundspeed.

A power plane can do the above and it is the better option, but full-size aircraft are often forced to fly 3 degrees over the ground regardless of conditions, to suit instrument landing systems, local patterns etc. Seeing this can deceive some modellers into thinking you have to fly like that, or that aircraft do fly like that! You can if you want to, there is no harm, but you need to allow for the fact that you will fly such an approach in wind at a higher throttle setting than on a calm day. Once again imagine the smoke, if you fly a normal approach path based on the ground but in a headwind, by the time you land the smoke trail will be far longer, and therefore a lower descent angle, than on a calm day. Since power controls the rate of descent, and your rate of descent is less if you try this type of ground referenced approach, you must have been using more power than on a calm day. Not convinced? Assume a plane approaches at 60mph = 1 mile a minute, for a 1 mile approach takes 1 minute and the approach started at 300 feet so it lost height at 300 feet per minute with the throttle set accordingly. The pilot goes around but next time he encounters a 30mph headwind on approach. Instead of approaching from closer he elects to keep the same 1 mile from 300 feet (3 degrees over the ground) approach. His airspeed is 60mph (fuselage at same up/down attitude as before) but now his ground speed is 30mph. It will take him 2 minutes to cover the 1 mile ground approach so now he must lose height at just 150fpm instead of 300fpm, and he must therefore use a higher power setting. That means more of a power change when closing the throttle prior to touchdown, which leads to a more pronounced nose drop and even if that is corrected for, a more severe rate of descent if done too early.

So, learn the angle of the fuz for each of your models on approach, because that is the angle you want for that airspeed regardless of how windy it is. As the wind speed increases you can bring your base leg closer, keep it the same distance but higher, or fly the same shape over the ground as on a calm day but be prepared to use a higher throttle setting. The first two options are better even when you have power (they are variants of the same thing really) as then you will be doing much the same thing should you go deadstick, and not get lead by habit into a deadstick approach from way downwind, which never reaches the runway. Bear in mind that when deadstick you will have a slightly lower nose attitude than when power is on, for the same airspeed. Your thumb will have the elevator at the same position as when power is on but the nose will be a bit lower so don't be tempted to pull back a bit more and get exactly the same attitude as when there is power. Learning to judge how the plane is flying and what airspeed it is at by getting feedback from your thumbs is one of those things that takes a long time to learn. Your thumb can actually tell you a great deal about your airspeed and how close you are to the stall!

The further downwind you fly your circuit to turn finals, the more likely you are to have turned too early. We tend to get used to turning finals when the model is at a particular angle from the runway where we are standing. So if you go further away and still turn finals at the normal angle you will not be over the centreline. Conversely if you fly closer such as in a wind, you may turn too late. Be prepared for this on a windy day, if you keep the base leg closer then be ready to turn finals at what looks like a little earlier than normal.

On the downwind leg sits an invisible little gremlin just waiting to flick your model into a spin as it goes past him. In a wind, you know the model scoots downwind rather fast. So many modellers are tempted to cut power (thinking that means they go slow!), the model descends so they pull back the elevator (thinking that makes them go up) and just before they turn base leg they have run out of airspeed, fooled by the wind-induced groundspeed into thinking they are still flying. The gremlin gives a horrid laugh and flicks his finger under one wingtip. Splat! Fly the downwind leg at the same fuselage attitude and same power setting as normal. If attitude and power are the same as normal then speed and height change will be the same, regardless of the wind.

If you ever realise that you are turning late onto finals, or if a crosswind is blowing the turn past the runway, DO NOT steepen the turn. Stall speed rises in a turn and the steeper the turn the higher the stall speed. It is not a linear increase either, it is exponential and once the bank gets to 60 degrees every little extra bit of bank causes a huge rise in stall speed. Since I hope you have already slowed the model on base leg, you may find the stall speed coming up to match the airspeed that you have! Not a problem on well behaved trainers but a dreadful habit to get into just because the model lets you get away with it. Do the same thing with your lovely Kyosho CAP 232 and you will kiss it goodbye. Keep the same bank that you normally use but of course just keep the turn going to get the model back towards the centreline.

Phew, that's enough for now. Hope this all helps, if not say so and I will save myself some time! If it does help, what else would help or are you having problems with?

Harry