Weight and Balance

Contents

• Weight and Balance Basics
• CG Location
• Ballast Weight
• CG Shift

Weight and Balance Basics

The weight and balance of the aircraft is extremely important to aircraft safety and can have adverse affects on performance and handling characteristics. The aircraft must balance (forward and aft) within the center of gravity (CG) while not exceeding the max gross takeoff weight (MGTOW). The two biggest factors that affect weight and balance are fuel and payload.

Weight and Balance Specs

CG Location

The CG location is 5/16 inches (8 mm) behind the leading edge of the main spar and is marked on the bottom of the fuselage. This corresponds to roughly 20% of the mean aerodynamic chord (MAC).

Ballast Weight

Modifying payloads or changing equipment will require balancing the aircraft. It is essential for any aircraft configuration to achieve proper balance within the CG range before flying. Ballast weight is often necessary to achieve this balance. Add the minimum required weight as far forward as practical. Always take the ballast weight into account when calculating fuel and payload capacity.

Checking Balance

1. Assemble the aircraft on flat ground
2. Install batteries, do not connect.
3. Ensure all payloads are secure and mounted in their final location.
4. Place the aircraft on a balancing stand or hang the aircraft using the FLM balance plates and a hoist.
   When lifting the aircraft from below, only press against the CG markers.

5. Observe which way the aircraft leans, nose heavy vs tail heavy, and add ballast weight as needed.
6. The aircraft must balance at the marked CG indication of 20%.
7. Weigh the aircraft. This weight is known as the "dry weight." The difference between the dry weight and the MGTOW of 180 lbs is your remaining fuel capacity for that given aircraft configuration.
   Never exceed the MGTOW for flight.

CG Shift

The aircraft has a CG-centric fuel tank and experiences minimal shift due to fuel consumption.