## Paper Airplane Center Of Lift And Gravity

If you don’t know the four basic aerodynamic forces that affect the flight of a paper airplane, read our article on why paper airplanes fly before diving into this one. This article takes a deeper look into the aerodynamic forces and gives additional tips on how to design a paper airplane for distance by understanding the center of lift and the center of gravity.

FINDING THE CENTER OF LIFT

The center of lift is where the pressure of lift is concentrated on your paper airplane. It’s sometimes referred to as the aerodynamic center. To find the center of lift, you’ll need to find an electric fan or hair dryer. Turn it on low or medium power. Now, balance the two sides of the wings of your paper airplane loosely on your thumb and index finger starting at the middle of the fuselage. With the nose tilted slightly downwards, place the paper airplane into the wind. The nose will start to lift simulating how the paper airplane flies in the air. The center of lift (CoL) is where the paper airplane remains vertical in flight while balancing on your finger and thumb.

FINDING THE CENTER OF GRAVITY

The center of gravity (CoG) is where the weight of the paper airplane is balanced. Finding the center of gravity is pretty easy. Pick up your paper airplane and try balancing the fuselage on your index finger starting from the center. As most paper airplanes are nose heavy, it will likely fall forward. Move your index finger closer to the nose until you find the balancing point, this is the center of gravity.

Another easy way of finding the center of gravity is to hold the paper airplane with the wings facing the ground. Hold onto the fuselage loosely with your thumb and index finger. Find the spot where the paper airplane is perfectly balanced!

LIFT & GRAVITY AS OPPOSING FORCES

As we discussed in earlier articles, lift is the force keeping the paper airplane in flight while gravity works against it to pull in down. The center of these forces act like an invisible string pushing the paper airplane upwards and downwards at a specific spot.

For simplicity sakes, what do you think will happen if the CoL is located in the back and the CoG is located in the front of the paper airplane. Imagine in your head there really are strings connected to the paper airplane at the two centers. There a string in the back pull the paper upwards and another string in the front pulling it down. The paper airplane is in the perfect position to nose dive, definitely not good!

What happens if the CoL is way in the front and the CoG is way in the back? It’s likely do a backflip!

Playing around with the center of gravity and lift will give you control over the natural tilt of the paper airplane. You can control the paper airplane to naturally tilt upwards, downwards, or with no tendency at all.

BALANCING CoL & CoG

Now that you have a clear understanding of how the center of lift and gravity opposes each other and its effect on paper airplanes, we can conclude that the best scenario is to have them close to each other. When they are far apart, it causes the paper airplane to either nose dive or flip over. Let’s explore what happens when CoL and CoG are in the exact same location..

Having perfect balance actually sounds like a great idea. The invisible string we spoke of earlier pulls upwards and downwards in the same place. The paper airplane would not have any tendencies to tilt at all.

What do you think will happen if a gush of wind blows the nose of the paper airplane upwards? Without any natural tilting tendencies, the nose of the paper airplane will likely remain its upward tilt causing the paper airplane to eventually flip over backwards.

To resolve this, we want to have the center of gravity in front of the center of lift. This causes the natural tendency of the paper airplane to tilt downwards. If a gust of wind causes the nose to lift upwards, the paper airplane will naturally correct itself and protect it from flipping over. Remember, the farther the CoG is in front of the CoL, the greater the tilt downward. As we discussed earlier, the paper airplane will nosedive.

With all that you’ve learned so far, it should be clear the best scenario for balance is to keep the CoG slightly in front of the CoL. This gives the paper airplane positive self correction and stability in flight.

FAST & FURIOUS PAPER AIRPLANES FOR DISTANCE

I hope your head isn’t spinning and that you now have a good understanding of how the center of lift and gravity works. Given all that your have learned about the aerodynamic forces so far, how would you place the center of gravity and the center of lift for a fast flying paper airplane?

For a fast flying paper airplane focus on placing the center of gravity and center of lift close together (CoG in front of the CoL) toward the front of the fuselage. The paper airplane should have small wings to minimize drag and improve wing strength. This type of paper airplane does no depend on lift to provide distance, instead you want to launch this type paper airplane with as much thrust as possible. Think about how a dart works. It’s no wonder this type of fast flying paper airplane is often referred to as “dart” paper airplanes.

SLOW & STEADY PAPER GLIDERS FOR DISTANCE

I’m a big fan of slow and steady paper airplane gliders. I love how they float in the air, this is how I became so intrigue with how paper airplanes fly in the first place. To accomplish this floating affect, you want the center of lift toward the middle of the fuselage. The center of gravity should be in the middle between the nose of the paper airplane and the center of lift. This gives the paper airplane a slight downwards angle and the nice floating effect.

Unlike dart styled paper airplanes, you want good sized wings to allow enough overall lift to oppose the downwards force caused by gravity. You don’t want the wings to be so large that it causes too much drag or the wing structure to be flimsy. For ultimate distance, you need to be able to throw the paper airplane with enough thrust upwards into the air but not too much so it deforms the wings. When it reaches its maximum height, the paper airplane slowly glides down to achieve long distances.

TEST & TEST SOME MORE

The beauty of folding paper airplanes for distance and speed is all the little adjustments you can make to completely change the way it flies. For example, you can adjust the center of gravity by using a paper clip. You can change the center of lift simply by rolling the ends of the wings upwards or downwards. These tiny adjustments amongst many others can completely change how your paper airplane flies.

To help you along your journey to make the best paper airplane for distance, here are some tips and tricks to make your paper airplane fly far. Good luck and bon voyage!