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Author Topic: Handling Crosswinds  (Read 129 times)

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Online Deerslayer

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Handling Crosswinds
« on: June 18, 2019, 07:15:24 AM »
New flyers, especially, usually dread crosswinds. The typical small, foamy model presents a significant challenge in this regard - unless one develops and practices techniques to deal with it. Here are some thoughts on the topic.

On a large, wide field such as KRCM, let me suggest that there are very few true crosswind situations that demand any special techniques, just some awareness and planning.

First of all, there are three significant crosswind situations: taxiing, take-off and landing. Let's deal with each one separately. This time we can talk about:

Taxiing

You have to taxi out from the pit area and line up for take-off, then turn directly into wind for the latter. There is no magic runway centerline marked out where you have to begin and to follow, and we have an extremely wide field, so use it! Go well out from the flight line, then you may be able to take off directly into wind, thereby avoiding a crosswind that you would either have to handle properly or risk swinging into the pilot stations as you proceed.

The taxi phase will be at least partially with a crosswind. If the wind is brisk, your little machine will want to do one or both of two things: swing into the wind (weathercocking), or, flip sideways or tumble. Tricycle gear planes are typically the worst for the latter.

The basic technique is to hold a major amount (usually, full) Aileron to keep the upwind wing from lifting. Now that the plane is somewhat stuck to the ground. it will likely still want to weathercock. So, hold partial or full Rudder over in the opposite direction to the Aileron control, i.e., you will have "crossed controls". Say the wind is coming in from your left side. You will be holding the Aileron stick to the left and the Rudder stick to the right. If you have good nosewheel ot tailwheel steering, you may not need very much of the Rudder/steering correction.
 
There is one more thing to consider, particularly with a taildragger. (Tricycle gear planes tend to look after themselves in this regard). That is, the plane may be reluctant to follow your Rudder/steering, command. You have two requirements here; make the Rudder effective and, keep the plane from trying to take off unexpectedly. So, with your taildragger, you will likely require putting in a lot of Up Elevator, probably full Up. Then, you need airflow over the tail surfaces it to make it all work. Be careful, just use the Throttle in short bursts, just enough to move the plane and get some Rudder effect. Don't speed up  and have an unplanned take-off or flip over.

That's all there is to it! Practice makes perfect pretty good. Take any opportunity to practice this, even when you don't need to.

We haven't discussed taxiing downwind. The discomfort level there can be a lot higher, even for more experienced flyers. Back-tracking to or from the pits, to or from the landing or take-off spot, without face-planting in front of your admirers or charging into something can occasionally be a tad challenging in high winds. Of course, you will be the one still enjoying flying in such conditions, while others are self-grounded, so don't let that possibility bother you.

Generally, when taxiing downwind, you will want to keep the Ailerons and Rudder at neutral and the Elevator may have to be either at neutral or perhaps slightly Up. It the Elevator is large and/or has lots of travel, full Up may allow the tail to be picked up, resulting in complete loss of control and possibly a nasty tumble. The problem with taxxing downwind is that, in order for any control surface to be properly effective, it needs airflow in the normal direction. This means that the control surface has to see sufficient relative headwind, i.e., the propwash plus groundspeed has to be stronger than the tailwind. Now, you may be getting into a much higher ground speed and slight shifts in wind can make steering problematic. Not a lot of guidance here, other than for you to experiment and practice. Good luck!


« Last Edit: June 19, 2019, 08:52:12 AM by Deerslayer »
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Handling Crosswinds - Take-off
« Reply #1 on: June 19, 2019, 08:50:19 AM »
Sooner or later, one has to deal with a crosswind during the most critical portions of a flight. Let's see how we get airborne in a nice, smooth and controlled manner.

Takeoff

One option may be to eliminate or significantly reduce the crosswind problem. There is no magic centerline down which you have to track during the take-off, at least not on a large, wide field such as at KRCM and especially with a small, light and reasonably powered model.

Assuming that you are stuck with a significant crosswind for the direction, there are a couple of things to work on. Keep the wings level! Do not let the upwind wing start to lift and either tumble your plane or start it wandering around while accelerating. Simple rule: Keep the right (Aileron) stick pointed slightly into the relative wind. As you accelerate toward lift-off (which should be a very short time), the crosswind that the plane actually sees will be reduced. Just keep those wings level! The plane will likely wish to weathercock, i.e. start heading off course. This is where the Rudder comes in. You may find that you are using somewhat crossed controls, at least until the plane breaks free of the ground. The Aileron stick will be pointed toward the one side while the Rudder is pointed somewhat in the other direction. That is OK. As flying speed is reached, you will be returning both controls to neutral.

If things start to get a bit wild, don't try to fight it, back off, return to your starting point, if necessary, and re-start from a stationary position.

As the plane leaves the ground, it may want to weathercock and deviate from your intended path. You are supposed to be in control, so don't just let it wander around, fly it! Keep the wings level until you are comfortably high above ground, then fly however you wish.

You can never do too many practice laps. Perhaps choose a time with moderate wind when you really don't need to do a crosswind take-off but select a runway where you will experience a crosswind. Practice makes Perfect pretty good.

I hope that this helps someone. Meanwhile, Keep your wings Level!
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Handling Crosswinds - Approach and Landing
« Reply #2 on: June 19, 2019, 09:08:27 AM »

Approach and Landing

One of the best reasons for executing a pattern, or circuit, is to allow you to settle down, assess wind conditions and decide how to deal with a situaion such as a crosswind.

So, you are going to land and are unable to approach/land directly into the wind. Perhaps you can minimize the effect of a strong crosswind by flying an approach at a significant angle to your runway's centerline. You are stuck with the crosswind, now let's deal with it.

Two common techniques are side-slipping and crabbing. Side-slipping is a technique for losing altitude and/or holding a heading while possibly dealing with a crosswind. It is not particularly easy, effective or comfortable to do with most models, especially the light electric machines. Let's forget about that, for now. Crabbing will be our answer.

As you begin your approach, remember the cardinal rule: Keep your wings level! Now, your flight path will be straight with respect to the block of air in which you are flying. However, as you descend, the wind velocity (its speed + direction) may change and require some adjustment to your flying. With your wings level, you will be able to gradually detect any deviation from your approach path. Let's assume that the wind is coming from behind you, crosswind to your chosen runway and trying push your plane away from you.  Aim the aircraft more in the crosswind direction - in this case, toward you. Your plane must be flying right toward you, right? Therefore, isn't the nose heading that way? Perhaps not so much. Don't worry, if you get it right, the plane's ground track will still be in the desired direction, down the runway and you won't end up landing it on top of you. If you were inside the aircraft, you would like to be looking straight down the runway but your eyes would be pointed somewhat toward the side instead of right down the center of the windscreen. Right up until just before touchdown.

Now you are getting close to touchdown. If you have enough room and are not travelling too fast, so you may be able to just flare and land, as is, somewhat at an angle from the runway centerline. If not, you start to neutralize the Rudder and accept a bit of drift just prior to touchdown. Of course, you must Keep the wings level and don't let your speed drop off until you are ready to flare.

The next time you go flying, fear not the dreaded crosswind. Dealing with it is simpler/easier than you think (and certainly a lot simpler than this lengthy discussion!).

Even if you don't have to face a crosswind on your preferred runway, choose another one that does present you with that challenge. Start out with small steps, in a light crosswind, not a gale. Do lots of patterns, get good at maintaining your approach track, don't bother actually touching down, just power up and circle around again - repeat, repeat ... Do the full pattern and landing, many times.  Practice makes Perfect Better.

I hope that this helps someone. Meanwhile, Keep your wings Level!
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