What is meant by specific impulse?

Specific impulse (usually abbreviated Isp) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. A propulsion system with a higher specific impulse uses the mass of the propellant more efficiently.

What is specific impulse equation?

We can divide this equation by the weight of the propellants to define the specific impulse. The word “specific” just means “divided by weight”. The specific impulse Isp is given by: Isp = Veq / g0. where g0 is the gravitational acceleration constant (32.2 ft/sec^2 in English units, 9.8 m/sec^2 in metric units).

What does a high specific impulse mean?

A high specific impulse means that a rocket needs less fuel to perform as well. If the specific impulse is lower, it means that the rocket needs more fuel to perform as well.

How does specific impulse affect a rocket?

The specific impulse of a rocket propellant is a rough measure of how fast the propellant is ejected out of the back of the rocket. A rocket with a high specific impulse doesn’t need as much fuel as a rocket with low specific impulse. The higher the specific impulse, the more push you get for the fuel that rushes out.

What are the units of specific impulse?

The delivered Specific Impulse (Isp) of the propellant is simply the Total Impulse divided by the propellant weight or mass. Thus, the units for Specific Impulse are pound-seconds per pound (lb-sec./lb), or simply “seconds”. In the SI system, the units are Newton-seconds per kilogram (N-sec/kg).

Which rocket technology has the highest specific impulse?

LH2-LOX propellant
The LH2-LOX propellant has the highest specific impulse of any commonly used rocket fuel, and the incredibly efficient RS-25 engine gets great gas mileage out of an already efficient fuel.

What will happen to thrust and specific impulse as the rocket is propelled to higher altitudes?

What will happen to thrust and specific impulse as the rocket is propelled to higher altitudes? Explanation: Atmospheric pressure decreases with increasing altitude. So the pressure thrust part of the total thrust increases and hence the total thrust increases.

Why is specific impulse measured in seconds?

The specific impulse (Isp) of a rocket motor is a measure of its thrust efficiency, which is the reason why Isp is measured in seconds. The specific impulse (Isp) of a rocket motor is a measure of its thrust efficiency, which is the reason why Isp is measured in seconds.

What is the difference between specific impulse and total impulse?

Total impulse (It) is defined as the integral of the thrust (F) over the operating duration (t) of the motor: This integral is represented by the area under the F-t curve. The delivered Specific Impulse (Isp) of the propellant is simply the Total Impulse divided by the propellant weight or mass.

What is total impulse rocket?

The total impulse (I) of a rocket is defined as the average thrust times the total time of firing.