Ramjets

ByRobert Espey

A ramjet is a jet engine that relies on forward momentum to create pressure instead of a moving piston or fan

Requires forward motion to produce thrust

Uses continuous combustion

Incoming air is slowed to subsonic by cone

Slowed air creates pressure needed for combustion

Fuel injected into pressurized air

Flame ignites mixture Air expands and flows

through nozzle Exhaust generates

forward thrust

Must be at least Mach1 before operating

The thrust produced is based on pressure differentials at different sides of the plane

Limited by excessive temperatures and pressures at higher speeds and low pressure differentials at low speeds

No moving parts Higher efficiencies Speeds limited

only by temperatures and pressures engine can handle

Schematic of a Ramjet

Schematic of a Scramjet (air remains supersonic)

VS.

Low Fuel Efficiency Caused by low compression ratios High speed creates drag

Only operates at speeds above Mach1

Ramjets and Scramjets have been used in missiles, helicopters, and the SR71 Blackbird with varying degrees of success.

The United States funded a nuclear scramjet project for missiles called ‘Project Pluto” Realized that ICBM’s did the job better and that

low flying radioactive reactors weren’t the best idea

“Ramjet Engines.” 3 Dec. 2008 <http://www.aardvark.co.nz/pjet/ramjets.htm>

“The Ramjet/Scramjet Engine.” 2 Dec. 2008 <http://www.aviation-history.com/engines/ramjet.htm>

“Here Comes the Flying Stovepipe.” Time Magazine. 3 Dec. 2008 <http://www.time.com/time/magazine/article/0,9171,834721-1,00.html>

“Ramjet.” Wikipedia. 2 Dec. 2008 <http://en.wikipedia.org/wiki/Ramjet>