What is specific impulse?
Q: What is specific impulse?
A: Specific impulse (often shortened to Isp) is a way to describe how well a rocket or jet engine performs. It can be used to compare rockets of different sizes and measure the amount of force an engine makes for each bit of fuel.
Q: How is specific impulse measured?
A: Specific impulse is measured by knowing how much fuel is in the engine and calculating how much force it produces for that amount of fuel.
Q: What does a high specific impulse mean?
A: A high specific impulse means that a rocket needs less fuel to perform as well, so it uses fuel more efficiently than one with a lower specific impulse.
Q: How can we use specific impulse to compare engines?
A: Specific Impulse can be used much like miles per gallon or litres per 100 kilometres are used to compare cars, allowing us to compare rocket or jet engines based on their efficiency.
Q: Does having a higher specific impulse mean an engine is 'more powerful'?
A: No, having a higher specific impulse does not necessarily mean an engine is 'more powerful'. In fact, the designs for engines with the highest specific impulses are usually the weakest in terms of acceleration power.
Q: How do two rockets with different engines but same amount of fuel race against each other?
A: In a race between two rockets with the same amount of fuel and two different engines, the one with the more powerful engine will take an early lead, but when it burns down all its fuel, the rocket with higher specific impulse will still have some fuel left and will continue accelerating until eventually overtaking its counterpart if there's enough distance for it to use its long-term advantage.
