What is a Sport Plane?

Well, technically, a Sport Plane is called a Light Sport Aircraft (LSA)

What is a LSA?

The FAA has defined this category of airplane to have:

• A maximum Stall speed of 45 Knots (kts)
• A maximum gross weight of 1,320 lbs.
• A fixed propeller (Also can be ground adjustable) 
• Fixed landing gear
• A maximum level flight speed of 120 kts. (138 mph)
• A Maximum of 2 person capacity
• An unpressurized cabin