1. What is Specific Impulse?

Specific Impulse (I_sp) is a measure of how efficiently a rocket uses propellant or a jet engine uses fuel. It represents the thrust produced per unit of propellant consumed over time.

2. How Does the Calculator Work?

The calculator uses the Specific Impulse equation:

Where:

• \( I_{sp} \) — Specific impulse (seconds)
• \( F \) — Thrust (Newtons)
• \( \dot{m} \) — Mass flow rate (kg/s)
• \( g \) — Standard gravity (9.81 m/s²)

Explanation: The equation shows that specific impulse is directly proportional to thrust and inversely proportional to the mass flow rate of propellant.

3. Importance of Specific Impulse

Details: Specific impulse is crucial in aerospace engineering as it determines the fuel efficiency of rocket and jet engines. Higher I_sp means less propellant is needed for a given amount of thrust.

4. Using the Calculator

Tips: Enter thrust in Newtons and mass flow rate in kg/s. Both values must be positive numbers. The calculator uses standard gravity (9.81 m/s²) in its computation.

5. Frequently Asked Questions (FAQ)

Q1: What are typical I_sp values for different engines?
A: Chemical rockets: 200-450s, Ion thrusters: 2000-8000s, Jet engines: 2000-8000s (at high speeds).

Q2: Why is specific impulse measured in seconds?
A: The units work out to seconds dimensionally, and it represents how long the engine can produce thrust equal to the weight of propellant consumed.

Q3: How does I_sp relate to exhaust velocity?
A: I_sp (in seconds) × g (9.81 m/s²) = effective exhaust velocity (in m/s).

Q4: What factors affect specific impulse?
A: Propellant type, combustion efficiency, chamber pressure, and nozzle design primarily determine I_sp.

Q5: Can I_sp be improved during flight?
A: Yes, through techniques like altitude compensation (changing nozzle expansion ratio) or using different propellant combinations in stages.