Ultralights and Conventional Planes: What's the Difference?
Joe Duff, Operation Migration Pilot

Conventional aircraft differ from ultralight aircraft in more than just size and appearance. The pilot controls them in different ways, too.

Understanding Center of Gravity
Our ultralight aircraft use a method of control called weight shift. Look at the photo above. The wing is like a hang glider wing; the trike (or three-wheeled cockpit and engine) hangs from the center of gravity of the wing.

If you've ever tried to balance a pencil on your finger, you've played with center of gravity. The center of gravity is the average location of the weight of an object. When an object is suspended so that it can move freely, its center of gravity is always directly below the point of suspension.

The center of gravity is very important in a conventional aircraft. If you load all the heavy stuff in the back, the aircraft will be out of balance like a teeter totter and the nose will be too high. This can cause a crash. The same is true if you load all the heavy stuff in the front. But it does not matter how you load a trike, because the trike still hangs from the center of the wing.

Comparing Wings
Wings of conventional aircraft have flaps and rudders, which are small sections of the wing that move. The flaps or rudders push up or down against the air, moving the wing up or down. In a weight shift aircraft like our ultralights, the entire wing moves, not just small sections of it. This is safer because it takes many cables, pulleys and hinges to connect those moving parts of the wing to the pilot's control stick. A trike has only one moving part: the pivot point where the wing attaches to the aircraft.

Anatomy of the Ultralight

North Wing
(no kingpost)

Do you see the two bars that hold the wing on? The back bar is bigger and holds the weight. It is called the mast. The front bar is lighter and removable. It is called the downtube. The bar we steer with is the control bar. The kingpost is that bar that sticks up above the wing and holds the top flying wires that support the wing when the trike is on the ground. Because those top wires can trap a bird in flight, we prefer to use the North Wings with no kingposts. But the Zoom wings (with the kingpost) fly slower and help us stay with the birds.

Journal or Discussion Questions
  • Center of gravity is important bird flight too. Where is a Whooping crane's center of gravity? Why do cranes and herons fly differently? To discover the amazing answers, explore How Birds Fly. Share your new knowledge with friends or family.
  • Why is it safer for cars and trucks to have low centers of gravity, or to have their centers of gravity located close to the road?
  • Learn more about the ultralight planes: How Does the Pilot Steer the Ultralight?
  • Make a two-column chart to compare ultralights with conventional planes.