Battery Weight Fraction Calculator

Battery Weight Fraction Formula:

\[ WBF = \frac{R}{E_{battery} \times 3600 \times \eta \times \frac{1}{[g]} \times LD_{maxratio}} \]

Range of Aircraft:

Battery Specific Energy Capacity:

J/kg

Efficiency:

(0-1)

Maximum Lift to Drag Ratio:

Battery Weight Fraction (WBF):

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1. What is Battery Weight Fraction?

Battery Weight Fraction is the ratio between battery weight to gross weight of an aircraft. It is a dimensionless number that indicates what portion of the total aircraft weight is occupied by the battery system.

2. How Does the Calculator Work?

The calculator uses the Battery Weight Fraction formula:

\[ WBF = \frac{R}{E_{battery} \times 3600 \times \eta \times \frac{1}{[g]} \times LD_{maxratio}} \]

Where:

\( R \) — Range of Aircraft (meters)
\( E_{battery} \) — Battery Specific Energy Capacity (J/kg)
\( \eta \) — Efficiency (0-1)
\( [g] \) — Gravitational acceleration (9.80665 m/s²)
\( LD_{maxratio} \) — Maximum Lift to Drag Ratio

Explanation: The formula calculates the fraction of aircraft weight that must be allocated to batteries to achieve a specified range, considering battery energy density, system efficiency, and aerodynamic performance.

3. Importance of Battery Weight Fraction

Details: Battery weight fraction is crucial for electric aircraft design as it directly impacts the aircraft's range, payload capacity, and overall performance. A lower battery weight fraction allows for more payload or better performance.

4. Using the Calculator

Tips: Enter range in meters, battery specific energy capacity in J/kg, efficiency as a decimal between 0-1, and maximum lift to drag ratio. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical battery weight fraction for electric aircraft?
A: Battery weight fraction typically ranges from 0.2 to 0.5 for most electric aircraft, depending on the desired range and battery technology.

Q2: How does battery technology affect the weight fraction?
A: Higher specific energy capacity batteries (more J/kg) result in lower weight fractions for the same range, or longer range for the same weight fraction.

Q3: Why is efficiency important in this calculation?
A: Efficiency accounts for energy losses in the propulsion system, including motor, controller, and transmission losses.

Q4: How does lift-to-drag ratio affect battery weight?
A: A higher lift-to-drag ratio means the aircraft can fly more efficiently, requiring less energy and therefore less battery weight for the same range.

Q5: Can this formula be used for other electric vehicles?
A: While the basic principles apply, this specific formula is optimized for aircraft where lift-to-drag ratio is a critical aerodynamic parameter.