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The Loop and Vertical Pulls
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The Loop

The loop is the most common means of exiting level flight, so we’ll discuss this maneuver next. This section includes parts of a loop, like a pull to a 45 degree line or a pull to vertical. Any straight pull should be flow the same, since the dynamics are alike.

The key to a loop is to keep the radius constant…and that is the tricky part. If we were flying with zero gravity, all we would have to do is pull the stick back and freeze it. The plane would then fly a perfect circle. The problem is that gravity is fighting us as we pull the nose of the plane up at the start of a loop. Once we get to the top, gravity is helping us pull the nose back down The amount of back pressure it takes to compensate for gravity is constantly changing, so we need to gradually change the amount of stick we use.

So what does a pilot need to know? Pull hardest at the bottom of a loop. As long as the nose is pointed up, gradually reduce the amount of pressure you are using. Over the top you will need little, if any, back pressure to keep the nose coming around…this is because gravity is doing the work for you. As long as the nose is down, gradually increase your back pressure. Your stick is never frozen - it must be constantly moving as long as the nose is tracking. That’s the basics. Now let’s look at some of the subtleties.

Power control in a loop is important. The goal is to fly at a constant speed. This is not for the judges, but to make it easier on you. Whenever speed changes the aircraft feel also changes. We want the plane to feel the same all the time. If your plane has plenty of power, then add the power as you start your pull. As you come over the top, gently reduce the power to idle. Add it back to half throttle approaching level at the bottom of the loop. If your plane is under powered (slows on a vertical line under full power), then lead with full power a second or two before you start your pull. The idea here is to get a jump on the power curve so you will not run out of airspeed over the top. If you do, you may have to use opposite stick to float over the top and keep the loop round. This is not a good thing, and is an indicator you need to start planning on a new airplane to meet your needs.

The same visual perspective problems we have during level flight still haunt us during loops. You will have a natural tendency to lean the pull towards yourself, because you are standing lower than the plane. If you fly in no wind and your loops still corkscrew towards you, then you are having trouble with this illusion.

Some planes naturally yaw left during the first 1/4th of a loop, when you are using the greatest back pressure. This is due to the affect the angle of attack has on the propeller. The way you know this is a factor is that whenever you pull a vertical up-line, you always end up angled to the left (assuming your wings were level going in). Minimize the “P” effect by flying a larger diameter loop and flying faster. These both reduce the angle of attack…and the “P” affect. If the plane still yaws left on the pull up, then you need to add a touch of right rudder (left if you are pushing an outside loop) during the first 90 degrees of pull. The affects should diminish enough over the top that rudder is not required once you get past the 90 degree point.

The best way to practice a loop is to fly several consecutive loops. Fly each tracked exactly over the previous…exitting right where the entry began. Any errors you make will be amplified. After a while you will train yourself to make the corrections you need to fly each one just like the previous. Next to straight and level flight, practice with your loops is the next most productive time you can spend. It will help you with every maneuver requiring a pull.

 

Windage correction:

Headwind and tailwind. If the wind is directly on the nose or tail, you will relax the amount of pull you use whenever the nose is tracking towards the wind. Likewise, increase the pull whenever the nose is tracking away from the wind. If you make no wind correction the loop will end up looking like a tall, leaning oval, and the exit point will end up downwind from the start point. Using the correction technique above, you will float the first quarter - speed up the second and third quarters - and float the fourth. You will then get a nice round loop.

Crosswind. This is trickier. You will be starting the loop with the nose angled - or crabbed - into the wind. If you just pull straight back without any rudder or bank change, the nose will be pointed away from the wind at the top of the loop. That’s the opposite of what we want. If you have trouble visualizing this, spend a few minutes with a stick plane and watch what happens with a straight pull. Continue the straight pull and the nose will be back into the wind when you get to the bottom of the loop. Another quirk of the crosswind loop is the bank angle on the vertical lines. If you just pull straight, when you reach vertical, the plane will be banked away from the wind. And you were thinking a loop was easy! The result is the loop will corkscrew downwind. So let’s fix that.

There are two techniques that will get you through a crosswind loop. Which you use depends on your rudder proficiency.

Rudder - the preferred. Hold a small amount of rudder into the wind - but do not add it until the second quarter of the loop. It is not necessary on the first quarter, as the nose will naturally fall in the direction you need due to gravity. You will continue to hold the very light rudder input for the last 3/4ths of the loop. That will fix our nose track problem over the top of the loop. To fix the bank problem, you will need to hold very, VERY slight aileron into to wind throughout the entire loop. The wings will stay perfectly flat, but the aileron into the wind is necessary to maintain that flat bank. Confusing? Just play with the stick model a little to understand why.

Aileron - an alternative. If the above is just too confusing, then you are probably not ready for it yet. In the mean time just remember this…always bank a little into the wind as you pull a loop. To do it, just hold a slight amount of aileron towards the wind throughout the maneuver. It’s that simple! Granted, you should technically be downgraded for the bank angle, but that is only 1 point for 10 degrees, and you will only be holding a couple of degrees. If you are smooth and consistent, the judges will not even notice it.

 

Tricks

Fly your loops large and deep into the box. This helps you see the shape better than when you fly close and tight. Judges tend to forget entry points and shapes if the maneuver takes a while…they should give you the benefit of the doubt.

If your airspeed slows - like at the top of a loop - relax the pull. You are trying to maintain a shape, so if you fly it slower, you need to pull it slower. Sometimes it will be necessary to actually push on the stick to keep the shape if you get really slow.

 

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