Ramjet

He could not test his invention due to the unavailability of adequate equipment since there was no way at the time for an aircraft to go fast enough for a ramjet to function properly.

In 1915, Hungarian inventor Albert Fonó devised a solution for increasing the range of artillery, comprising a gun-launched projectile united with a ramjet propulsion unit, thus giving a long range from relatively low muzzle velocities, allowing heavy shells to be fired from relatively lightweight guns.

In 1940, the Kostikov-302 experimental plane was designed, powered by a liquid fuel rocket for take-off and ramjet engines for flight.

In 1954, NPO Lavochkin and the Keldysh Institute began development of a Mach 3 ramjet-powered cruise missile, Burya.

Several ram jets were designed, built, and ground-tested at the Kawasaki Aircraft Company's facility in Gifu during the Second World War.

Later, as petrol became scarce in Germany, tests were carried out with blocks of pressed coal dust as a fuel (see e.g. Lippisch P.13a), which were not successful due to slow combustion.

[11] Stovepipe (flying/flaming/supersonic) was a popular name for the ramjet during the 1950s in trade magazines such as Aviation Week & Space Technology[12] and other publications such as The Cornell Engineer.

The ramjet Gorgon IVs, made by Glenn Martin, were tested in 1948 and 1949 at Naval Air Station Point Mugu.

In the late 1950s the US Navy introduced a system called the RIM-8 Talos, which was a long range surface-to-air missile fired from ships.

The Blue Envoy project was supposed to equip the country with a long range ramjet powered air defense against bombers, but the system was cancelled.

The system was designed as a second line of defense in case attackers were able to bypass the fleet of defending English Electric Lightning fighters.

In the 1960s the Royal Navy developed and deployed a ramjet powered surface to air missile for ships called the Sea Dart.

Eminent Swiss astrophysicist Fritz Zwicky was research director at Aerojet and holds many patents in jet propulsion.

The air velocity entering the combustor has to be low enough such that continuous combustion can take place in sheltered zones provided by flame holders.

Normally, the combustor must be capable of operating over a wide range of throttle settings, matching flight speeds and altitudes.

Usually, a sheltered pilot region enables combustion to continue when the vehicle intake undergoes high yaw/pitch during turns.

Over-fuelling the combustor can cause the final (normal) shock in the diffuser to be pushed forward beyond the intake lip, resulting in a substantial drop in airflow and thrust.

The propelling nozzle is a critical part of a ramjet design, since it accelerates exhaust flow to produce thrust.

Initially, the bladder forms a close-fitting sheath around the compressed air bottle from which it is inflated, which is mounted lengthwise in the tank.

[26] A ramjet generates no static thrust and needs a booster to achieve a forward velocity high enough for efficient operation of the intake system.

This approach has been used on solid-fuel ramjets (SFRJ), for example 2K12 Kub, liquid, for example ASMP, and ducted rocket, for example Meteor, designs.

This offers the advantages of elimination of the hazard to launch aircraft from the boost debris, simplicity, reliability, and reduced mass and cost,[27] although this must be traded against the reduction in performance of a dedicated booster nozzle.

SFIRRs are preferred over LFRJs for some applications because of the simplicity of the fuel supply, but only when the throttling requirements are minimal, i.e. when variations in altitude or speed are limited.

Ramjets generally give little or no thrust below about half the speed of sound, and they are inefficient (specific impulse of less than 600 seconds) until the airspeed exceeds 1,000 kilometres per hour (280 m/s; 620 mph) due to low compression ratios.

However, ramjets generally outperform gas turbine-based jet engine designs and work best at supersonic speeds (Mach 2–4).

The performance of conventional ramjets falls off above Mach 6 due to dissociation and pressure loss caused by shock as the incoming air is slowed to subsonic velocities for combustion.

During the Cold War, the United States designed and ground-tested a nuclear-powered ramjet called Project Pluto.

This system, intended for use in a cruise missile, used no combustion; a high-temperature, unshielded nuclear reactor heated the air.

[35] On 1 March 2018 President Vladimir Putin announced a nuclear-powered ramjet cruise missile capable of extended long range flight.

A concept was created by NASA for recombining this (thin) gas back to diatomic molecules at orbital speeds to power a ramjet.