| Although today, the technological
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| | being by far the most popular.
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| advancement of airplane powerplant
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| | Engine sizes - and how they are
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| specially on the electric motors which
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| | specified.
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| now uses Lithium Polymer batteries, we
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| | Engine sizes are specified by
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| should also learn the internal combustion
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| | displacement or the interior volume swept
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| type since the development of those
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| | by the piston in making its stroke up and
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| miniature airplanes and helicopters owe
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| | down the cylinder (swept volume) In the
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| so much. There are two main types of
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| | case of diesels, displacement is always
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| model airplane engine - glow engines and
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| | quoted in cubic centimeters or cc (mainly
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| diesels. Although the ignition type is
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| | because the model diesel originated in
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| popular on big birds (1/4 scale), we will
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| | Continental Europe). In the case of glow
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| concentrate on the 'standard' model
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| | engines, displacement is (nearly) always
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| engines. Glow engine are by far the more
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| | quoted in cubic inches or cubic inches
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| numerous and popular, faster revving and
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| | (because this type originated in the
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| generally more powerful size for size.
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| | United States) Manufacturer produce glow
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| They are suitable for powering all types
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| | engine in a more or less standard range
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| of model aircraft and are produced in
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| | of sizes, originally representing logical
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| three general categories - standard
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| | steps in power output. These are 0.049
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| engines for general use; racing engines
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| | cubic inch (also known as 1/2A); 0.09
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| for competition models; and RC engines
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| | cubic inch (also known as Class A); 0.19
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| for radio controlled aircraft. Standard
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| | cubic inch, 0.29cubic inch, 0.35cubic
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| engines may also be used for radio
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| | inch, 0.49 cubic inch and 0.60 cubic inch
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| controlled models fitted with a throttle
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| | Quite often the cubic inch is dropped and
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| control or RC carburetor. This applies
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| | just the figures quoted 049, 09, 19, etc.
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| particularly to smaller engine sizes.
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| | Some manufacturers produce additional
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| Larger RC engines are generally specially
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| | sizes, e.g. smaller than- 0.049 cubic
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| designed to produce maximum power at more
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| | inch for powering tiny models, and
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| moderate revs than either standard or
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| | intermediate sizes to cater for a
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| racing engines.
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| | particular size or type of model, such as
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| Glow engines have three particular
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| | 0.40 cubic inch for RC models. The need
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| disadvantages, although these are
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| | for intermediate sizes is rather more
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| outweighed by the simplicity of operation
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| | commercial than realistic however.
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| and general flexibility of the type.
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| | Classification of porting nearly all
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| First they need a special type of
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| | present day model airplane engine are of
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| ignition plug, known as a glow plug,
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| | similar layout, the main differences
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| which can burn out and need replacement.
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| | being in the method of inducting the fuel
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| They also need a battery connected to the
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| | air mixture into the crankcase and then
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| plug for starting (and if the battery is
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| | transferring it to the top of the
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| 'flat' the engine will not start!), and
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| | cylinder. Induction is controlled by a
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| special alcohol-base fuels which are a
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| | rotary valve, either a hole opening into
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| little more costly than diesel fuels and
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| | a hollow section of the crankshaft, or a
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| also attack paints and cellulose dope
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| | disc with a hole, driven by the
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| finishes. For this reason, model aircraft
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| | crankshaft. In either case, sheathe hole
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| powered by glow engines must be finished
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| | in the crankshaft (or disc) comes
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| in fuel proof dopes, or given a final
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| | opposite the end of the carburetor tube
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| coat of special fuel proof paint.
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| | the intake port is opened and then closed
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| Diesels are self-contained engines that
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| | by subsequent rotation of the crankshaft.
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| they need only a supply of suitable fuel
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| | The circumferential length of this hole
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| to run. They are generally heavier and
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| | determines the intake timing.
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| more robust than glow engines, so they
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| | When induction takes place in front of
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| are usually longer lasting. They vibrate
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| | the cylinder (through the crankshaft),
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| more and are less responsive to throttle
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| | the layout is known as front rotary
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| control than glow engines, so are not
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| | (readily distinguished by the carburetor,
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| generally recommended for powering radio
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| | or strictly speaking, the intake tube)
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| controlled models. They cannot rev as
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| | coming in front of the cylinder. With
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| fast as a racing glow engine, so are less
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| | rear rotary engines the intake tube
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| competitive in this respect. On the other
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| | attaches directly to the back of the
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| hand they can be excellent power units
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| | crankcase. Transfer of fuel and air
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| for small and modest: size free fight
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| | mixture drawn into the crankcase to the
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| 'sports' models and certain types of
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| | top of the cylinder is controlled by
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| control-line models. Diesels are produced
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| | piston movement opening the top of a
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| in a much more restored range of sizes
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| | transfer port (or ports) formed in the
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| than glow engines. Very small diesels
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| | side of the cylinder. This porting may be
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| (smaller than 0.5cc) are difficult (and
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| | conventional, or specially arranged to
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| costly) to produce and can prove tricky
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| | give a 'boost' to the charge to fill the
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| to start and adjust. At the other end of
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| | cylinder head in the most effective
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| the scale, diesels larger than about
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| | manner. The latter is a relatively new
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| 3.5cc generally prove disappointing in
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| | development with model airplane engine
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| performance. Thus diesel production is
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| | and is known as schnuerle porting. It is
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| virtually limited to a size range from
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| | now a feature of many high performance
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| 0.5 to 3.5cc with the 1cc and 1.5cc sizes
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| | glow engines.
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