Jetex engine
Encyclopedia
The Jetex engine was a type of solid-fuel rocket engine
produced for use as a powerplant for model aircraft
. Originally developed in 1947, by Wilmot, Mansour & Company Ltd of Southampton
, it was first demonstrated to the modelling press in early 1948, and was available to the public in June 1948, when Aeromodeller featured Jetex power on its front cover. The first motors were the Jetex 100 and 200, with the more powerful Jetex 350 following in November 1948. The most popular motor, the Jetex 50, was introduced in May 1949, along with kits for a model plane and model car using Jetex power.
Jetex engines were powered by a solid pellet of guanidine nitrate
, which burnt to release a variety of gases in copious volume, leaving no solid residue or ash. Thrust developed was fairly modest, suitable for horizontally launched flying models rather than vertically launched rockets. The exhaust gas was not excessively hot, which conferred a safety advantage. Fuel and wick to ignite the pellets was manufactured by Imperial Chemical Industries
(ICI). The engine casing was made of an aluminium alloy and was reusable, new fuel pellets and ignition wick being a consumable that could be bought and used in the engine.
Jetex power made a big impact in the late forties and early fifties, allowing new sorts of models, scale and duration, to be designed. Its popularity waned after the mid-fifties, and by the 1970s was largely forgotten. Recently, there has been a reawakening of interest in Jetex—in the mid 1990s, a similar device called the Rapier was launched, and many old plans for Jetex powered models were dusted off and built with the new engines.
Compared with modern Estes
-type rockets, the Jetex is quite different. It has a much gentler, cooler exhaust, so flight characteristics tend to feature gradual acceleration rather than firework-like performance. The cooler exhaust is easier to handle and does not require extensive flameproofing of the airframe. However, the fuel is more toxic and requires special handling to keep it dry and in working condition (the fuel is slightly deliquescent and will gradually absorb moisture from the atmosphere which quickly renders it inactive). As a result, Jetex were quite unreliable, often failing to ignite.
Rocket engine
A rocket engine, or simply "rocket", is a jet engineRocket Propulsion Elements; 7th edition- chapter 1 that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
produced for use as a powerplant for model aircraft
Model aircraft
Model aircraft are flying or non-flying models of existing or imaginary aircraft using a variety of materials including plastic, diecast metal, polystyrene, balsa wood, foam and fibreglass...
. Originally developed in 1947, by Wilmot, Mansour & Company Ltd of Southampton
Southampton
Southampton is the largest city in the county of Hampshire on the south coast of England, and is situated south-west of London and north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest...
, it was first demonstrated to the modelling press in early 1948, and was available to the public in June 1948, when Aeromodeller featured Jetex power on its front cover. The first motors were the Jetex 100 and 200, with the more powerful Jetex 350 following in November 1948. The most popular motor, the Jetex 50, was introduced in May 1949, along with kits for a model plane and model car using Jetex power.
Jetex engines were powered by a solid pellet of guanidine nitrate
Guanidine nitrate
Guanidine nitrate is a high energy fuel used in some gas generator and solid rocket propellant applications.-Overview:Guanidine nitrate is the salt formed from guanidine and nitric acid. It has the chemical formula C3NO3. It has been used as a monopropellant in the Jetex engine for model airplanes....
, which burnt to release a variety of gases in copious volume, leaving no solid residue or ash. Thrust developed was fairly modest, suitable for horizontally launched flying models rather than vertically launched rockets. The exhaust gas was not excessively hot, which conferred a safety advantage. Fuel and wick to ignite the pellets was manufactured by Imperial Chemical Industries
Imperial Chemical Industries
Imperial Chemical Industries was a British chemical company, taken over by AkzoNobel, a Dutch conglomerate, one of the largest chemical producers in the world. In its heyday, ICI was the largest manufacturing company in the British Empire, and commonly regarded as a "bellwether of the British...
(ICI). The engine casing was made of an aluminium alloy and was reusable, new fuel pellets and ignition wick being a consumable that could be bought and used in the engine.
Jetex power made a big impact in the late forties and early fifties, allowing new sorts of models, scale and duration, to be designed. Its popularity waned after the mid-fifties, and by the 1970s was largely forgotten. Recently, there has been a reawakening of interest in Jetex—in the mid 1990s, a similar device called the Rapier was launched, and many old plans for Jetex powered models were dusted off and built with the new engines.
Compared with modern Estes
Estes Industries
Estes Industries is a company based in Penrose, Colorado, USA that designs and builds model rocket and model aircraft engines and kits. They were the best known model rocket company during the "golden age of rocketry" in the 1970s and early 1980s, competing primarily with Centuri Engineering and a...
-type rockets, the Jetex is quite different. It has a much gentler, cooler exhaust, so flight characteristics tend to feature gradual acceleration rather than firework-like performance. The cooler exhaust is easier to handle and does not require extensive flameproofing of the airframe. However, the fuel is more toxic and requires special handling to keep it dry and in working condition (the fuel is slightly deliquescent and will gradually absorb moisture from the atmosphere which quickly renders it inactive). As a result, Jetex were quite unreliable, often failing to ignite.
External links
- Jetex.org This non-profit site is "the premier Web resource for information and advice about models powered by micro rocket motors, especially those exemplified by the Jetex series of engines".