Glider Weight and Balance – Formula and Example

This guide explains how to calculate glider weight and balance step by step, including the formula, a practical example, and the basics of center of gravity (CG).

What is weight and balance?

Weight and balance refers to the distribution of mass in the aircraft and the position of the center of gravity (CG). The CG must remain within defined limits to ensure safe and stable flight.

Weight and balance formula

Each mass creates a moment:

Required data

• empty weight of the glider
• arm values from the flight manual
• pilot and passenger weight
• water ballast
• trim weights
• additional equipment

Example calculation

Simple example:

• Pilot: 80 kg × 0.5 m = 40 kgm
• Glider: 300 kg × 0.3 m = 90 kgm
• Ballast: 50 kg × 0.4 m = 20 kgm

Total moment: 150 kgm
Total weight: 430 kg

The calculated CG must then be checked against the allowable limits.

Step-by-step calculation

1. Record all weights

Include empty weight, pilot, ballast, and additional loads.

2. Use official arm values

Always use values from the aircraft manual.

3. Calculate moments

Multiply each weight by its arm.

4. Sum up

Add all weights and moments.

5. Calculate CG

Divide total moment by total weight.

6. Check limits

Ensure the CG is within the allowed range.

Why weight and balance matters

The center of gravity directly affects stability, control, and performance. Incorrect weight distribution can lead to unsafe flight conditions.

Calculate weight and balance with TrimCalc

Manual calculations can be time-consuming and error-prone. TrimCalc allows you to enter weights and instantly calculate the center of gravity.