Rocket Engines

Technology Roadmap Sections and Deliverables

Roadmap Overview

The primary function of rocket engines is to convert chemical energy to kinetic energy. This means that a rocket engine would be placed squarely on the cell “Transforming Energy” in our 5x5 technology matrix. There are several different styles of rocket engines that are used today (all of which meet the primary functional requirements) but the perform those functions in slightly different ways with slightly different architectures. These architectures are all determined by their fuel type and their fuel consumption method. The rocket engines we will examine here include: solid rockets, open cycle liquid fuel, closed cycle full flow liquid fuel, and nuclear. Below is a table comparing some key figures of merit for some examples of each of these categories.

Figures of Merit

Tsiolkovsky Rocket Equation (m/s)

Δv = ve*ln(m0/mf) ve = effective exhaust velocity m0 = initial total mass including fuel and oxidizer mf = final mass without fuel and oxidizer

Specific Impulse (s)

Isp = ve/g0 ve = average exhaust speed along the axis of the engine (either at sea level or vacuum) g0 = standard gravity in m/s2

Net Thrust (N)

Fn = M*Ve M = exhaust gas mass flow Ve = effective exhaust velocity

Thrust-to-weight ratio (N/kg)

TTW = Net Thrust (N)/m (kg)

       m = dry mass of the engine