31-08-2017, 10:36 AM
The Jetex engine is a type of solid fuel rocket engine produced to be used as an engine for model airplanes. Originally developed in 1947 by Wilmot, Mansour & Company Ltd of Southampton, it was first demonstrated to the modeling press in early 1948, and was made available to the public in June 1948, when Aeromodeller introduced Jetex on its cover. The first engines were the Jetex 100 and 200, with the most powerful Jetex 350 in November 1948. The most popular engine, the Jetex 50, was introduced in May 1949, along with kits for an airplane model and car model with Jetex energy.
Jetex engines are powered by a solid guanidine nitrate pellet, which is burned to release a variety of gases in a copious volume, leaving no solid residue or ash. The thrust developed is fairly modest, suitable for horizontally thrown flight models rather than vertically thrown launches. The exhaust gas is not excessively hot, which gives it a safety advantage. The fuel and wick to ignite the granules were manufactured by Imperial Chemical Industries (ICI). The engine casing was made of an aluminum alloy and reusable, the new fuel pellets and ignition wick were a consumable that could be purchased and used in the engine.
The power of the Jetex had a great impact in the late 1940s and early 1950s, allowing new types of models, scale and duration to be designed. Its popularity declined after the mid-1950s, and by the late 1970s it was largely forgotten. Recently, there has been an awakening of interest in Jetex; in the mid-1990s, a similar device called Rapier was launched, and many older plans for the Jetex engine models were dusted off and built with the new engines.
Compared to modern Estes rockets, the Jetex is quite different. It has a much smoother, cooler exhaust, so the flight characteristics tend to offer gradual acceleration rather than fire-like performance. The cooler exhaust is easier to handle and does not require extensive ignifugation of the structure of the aircraft. 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 will quickly render it inactive). As a result, Jetex was quite unreliable, often failing to light up.
Jetex engines are powered by a solid guanidine nitrate pellet, which is burned to release a variety of gases in a copious volume, leaving no solid residue or ash. The thrust developed is fairly modest, suitable for horizontally thrown flight models rather than vertically thrown launches. The exhaust gas is not excessively hot, which gives it a safety advantage. The fuel and wick to ignite the granules were manufactured by Imperial Chemical Industries (ICI). The engine casing was made of an aluminum alloy and reusable, the new fuel pellets and ignition wick were a consumable that could be purchased and used in the engine.
The power of the Jetex had a great impact in the late 1940s and early 1950s, allowing new types of models, scale and duration to be designed. Its popularity declined after the mid-1950s, and by the late 1970s it was largely forgotten. Recently, there has been an awakening of interest in Jetex; in the mid-1990s, a similar device called Rapier was launched, and many older plans for the Jetex engine models were dusted off and built with the new engines.
Compared to modern Estes rockets, the Jetex is quite different. It has a much smoother, cooler exhaust, so the flight characteristics tend to offer gradual acceleration rather than fire-like performance. The cooler exhaust is easier to handle and does not require extensive ignifugation of the structure of the aircraft. 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 will quickly render it inactive). As a result, Jetex was quite unreliable, often failing to light up.