Isopropyl nitrate (IPN, 2-propyl nitrate) is a colorless liquid

monopropellant Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with biprop ...

. It is used as a

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...

cetane Hexadecane (also called cetane) is an alkane hydrocarbon with the chemical formula C16H34. Hexadecane consists of a chain of 16 carbon atoms, with three hydrogen atoms bonded to the two end carbon atoms, and two hydrogens bonded to each of the 14 ...

improver. IPN is a low-sensitivity explosive, with a

detonation velocity Explosive velocity, also known as detonation velocity or velocity of detonation (VoD), is the velocity at which the shock wave front travels through a detonated explosive. Explosive velocities are always faster than the local speed of sound in t ...

of approximately 5400 m/s. Isopropyl nitrate is extremely flammable and burns with a practically invisible flame. This presents unique hazards in its handling. The flame is significantly less luminous than hydrogen or methanol flame and is only visible due to the turbulent hot air it generates. Isopropyl nitrate was previously used in a

jet engine A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...

rapid starting system for military interceptor aircraft (a requirement for fast

scrambling Scrambling is a mountaineering term for ascending steep terrain using one's hands to assist in holds and balance.''New Oxford American Dictionary''. It is also used to describe terrain that falls between hiking and rock climbing (as a “scramb ...

, as it provided simultaneous, near-instantaneous engine starting for twin engines) and was known as AVPIN. The exhaust fumes from an AVPIN monopropellant engine may themselves be explosive, if mixed with further air. Early systems, as used on the

Gloster Javelin The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...

, used a simple pressurising cartridge and had a poor reputation for misfires, including engine-destroying explosions. Nevertheless,

Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...

was able to demonstrate that the fuel is extremely stable and that a cannon shell could be fired through a container of it with no dramatic effect. Isopropyl nitrate was also sold by the

Turbonique Turbonique was a company founded in 1962 by Clarence Eugene "Gene" Middlebrooks Jr of Orlando, Florida. Middlebrooks, born 3 August 1931, was a native of Jonesboro, Georgia, had studied mechanical engineering at Georgia Tech and had worked for ae ...

company under the brand name "Thermolene" as a fuel for their line of turbine-powered "drag axles" and superchargers, during the 1960s. It is officially classed as safe to transport provided it is labelled as flammable. Although engine starters do not require an air supply for their basic operation, air was supplied to later designs, such as that of the

English Electric Lightning The English Electric Lightning is a British fighter aircraft that served as an interceptor during the 1960s, the 1970s and into the late 1980s. It was capable of a top speed of above Mach 2. The Lightning was designed, developed, and manufa ...

, by an automatic scavenge pump simply to control these fumes. The history of AVPIN use on the Lightning demonstrated it was both safe and effective in use. The reduced availability of AVPIN is now a restriction on the continued operation of some preserved military aircraft, such as Lightnings in the UK and South Africa and some are thus being converted to electric starting. It has also been used as a

fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...

for power supply and actuation in guided weapons, notably in the British

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...

References

External links

EPA Substance registry system
{dead link, date=November 2017 , bot=InternetArchiveBot , fix-attempted=yes Liquid explosives Alkyl nitrates Isopropyl esters Monopropellants