Ramjets By Robert Espey

What is a Ramjet? 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

How Does it Work? 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

How Does it Work? (Cont.) 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

Schematic of a Scramjet (air remains supersonic) Advantages No moving parts Higher efficiencies Speeds limited only by temperatures and pressures engine can handle Schematic of a Ramjet VS. Schematic of a Scramjet (air remains supersonic)

Disadvantages Low Fuel Efficiency Only operates at speeds above Mach1 Caused by low compression ratios High speed creates drag Only operates at speeds above Mach1

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

Applications 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

Works Cited “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>