Relaxed stability

Imagine you're trying to balance yourself on a bike. If you're sitting on the seat and leaning forward, the bike feels pretty stable. You're not wobbling around too much and you can keep yourself upright without much effort. This is what we call a "stable" balance, where leaning forward keeps you balanced.

Now imagine that instead of sitting on the seat and leaning forward, you're sitting on the handlebars and leaning back. The bike doesn't feel as stable anymore, and you might find yourself wobbling around a lot more. You have to actively work to keep yourself balanced, or you might fall off. This is what we call "relaxed" stability, where leaning back makes you feel like you're going to fall off.

In aviation, the same concepts apply. An airplane that is designed to be "stable" in flight will naturally want to stay flying straight and level without much input from the pilot. But an airplane that is designed for "relaxed" stability might require more constant input from the pilot to stay flying straight and level. This can be helpful in some situations, like when the airplane needs to maneuver quickly or be very responsive to the pilot's commands. But it can also be more challenging for the pilot to fly, since they have to work harder to keep the airplane under control.

Overall, relaxed stability means that the airplane is designed to be more maneuverable, but also requires more constant attention from the pilot to keep it under control. It's a trade-off between agility and stability.