More unusual configurations
Common cylinder configurations include the straight or inline configuration, the more compact V configuration, and the wider but smoother flat or boxer configuration. Aircraft engines can also adopt a radial configuration, which allows more effective cooling. More unusual configurations such as the H, U, X, and W have also been used.
Multiple cylinder engines have their valve train and crankshaft configured so that pistons are at different parts of their cycle. It is desirable to have the piston's cycles uniformly spaced (this is called even firing) especially in forced induction engines; this reduces torque pulsations21 and makes inline engines with more than 3 cylinders statically balanced in its primary forces. However, some engine configurations require odd firing to achieve better balance than what is possible with even firing. For instance, a 4-stroke I2 engine has better balance when the angle between the crankpins is 180° because the pistons move in opposite directions and inertial forces partially cancel, but this gives an odd firing pattern where one cylinder fires 180° of crankshaft rotation after the other, then no cylinder fires for 540°. With an even firing pattern the pistons would move in unison and the associated forces would add.
Multiple crankshaft configurations do not necessarily need a cylinder head at all because they can instead have a piston at each end of the cylinder called an opposed piston design. Because fuel inlets and outlets are positioned at opposed ends of the cylinder, one can achieve uniflow scavenging, which, as in the four-stroke engine is efficient over a wide range of engine speeds. Thermal efficiency is improved because of a lack of cylinder heads. This design was used in the Junkers Jumo 205 diesel aircraft engine, using two crankshafts at either end of a single bank of cylinders, and most remarkably in the Napier Deltic diesel engines. These used three crankshafts to serve three banks of double-ended cylinders arranged in an equilateral triangle with the crankshafts at the corners. It was also used in single-bank locomotive engines, and is still used in marine propulsion engines and marine auxiliary generators.
Why have some means of transport?
Nowadays it is difficult to imagine life without the automotive industry. Public transportation, private cars and buses at the end of the truck the goods to any kind of shops are an integral part of our everyday life. Moving cars is very comfortable, so it's no surprise that it has now become almost necessary to lead a comfortable life element. Settlement of the simplest things in a quick way, or even trips on shorter routes are really enjoyable when you have your own car or motorcycle. For many people, the same drive various means of transport is a very nice feeling. Moreover, the use of buses or cars is sometimes necessary. Carrying heavy goods they are most often carried out also by means of heavy equipment moving on the roads.
Public costs - car issue
The external costs of automobiles, as similarly other economic externalities, are the measurable costs for other parties except the car proprietor, such costs not being taken into account when the proprietor opts to drive their car. According to the Harvard University,11 the main externalities of driving are local and global pollution, oil dependence, traffic congestion and traffic accidents; while according to a meta-study conducted by the Delft University12 these externalities are congestion and scarcity costs, accident costs, air pollution costs, noise costs, climate change costs, costs for nature and landscape, costs for water pollution, costs for soil pollution and costs of energy dependency. The existence of the car allows on-demand travel, given, that the necessary infrastructure is in place. This infrastructure represents a monetary cost, but also cost in terms of common assets that are difficult to represent monetarily, such as land use and air pollution.