To make a current flow, you have to push on the charges. How fast they move, in response to a given push, depends on the nature of the material. For most substances, the current density $\mathbf{J}$ is proportional to the force per unit charge, $\mathbf{f}$.

This chapter surveys some topics that could influence widespread VR usage in the future, but are currently in a research and development stage. Sections 13.1 and 13.2 cover the forgotten senses. Earlier in this book, we covered vision, hearing, and balance (vestibular) senses, which leaves touch, smell, and taste. Section 13.1 covers touch, or more generally, the somatosensory system. This includes physiology, perception, and engineering technology that stimulates the somatosensory system. Section 13.2 covers the two chemical senses, smell and taste, along with attempts to engineer “displays” for them. Section 13.3 discusses how robots are used for telepresence and how they may ultimately become our surrogate selves through which the real world can be explored with a VR interface. Just like there are avatars in a virtual world (Section 10.4), the robot becomes a kind of physical avatar in the real world. Finally, Section 13.4 discusses steps toward the ultimate level of human augmentation and interaction: brain–machine interfaces.

Classical mechanics obeys the principle of relativity: the same laws apply in any inertial reference frame. By “inertial” I mean that the system is at rest or moving with constant velocity.1 Imagine, for example, that you have loaded a billiard table onto a railroad car, and the train is going at constant speed down a smooth straight track. The game will proceed exactly the same as it would if the train were parked in the station; you don’t have to “correct” your shots for the fact that the train is moving – indeed, if you pulled all the curtains, you would have no way of knowing whether the train was moving or not.

The Fokker Dr.1 triplane is without doubt one of the most well-known fighter types of the First World War. However, it was preceded on the front much earlier by a similar British type; the Sopwith Triplane. Although it was built, just like the Fokker Dr.1, in relatively low numbers, it never got as famous as the Dreidecker flown by the German ace Manfred von Richthofen. In fact this was quite undeserved; the Sopwith Triplane entered the front much earlier than the Fokker Dr.1 and it was flown very successfully by a number of British aces before it was replaced by the much more known Sopwith Camel. Most famous Triplane ace was Raymond Collishaw, who scored no less than 34 of his total of 60 aerial victories on the Sopwith Triplane!

RISE AND FALL OF THE SOPWITH AIRCRAFT COMPANY LTD. AT KINGSTON-UPON-THAMES

T.O.M. Sopwith (Thomas) was born in Kensington, London on 18 January 1888. His father was a civil engineer who died when Thomas Sopwith still was a child. He followed a technical education and soon became very interested in aviation. He taught himself to fly, making his first solo flight on 22 October 1910. Although his first flight was very short and ended in a crash, he did not give up and he soon gained his flying certificate. On 18 December 1910, Sopwith won a £4000 prize for the longest flight from England to the Continent in a British-built aeroplane, flying 169 miles (272 km) in 3 hours 40 minutes. He used the winnings to set up the Sopwith School of Flying at Brooklands. In 1912 he set up, together with Fred Sirgist, a company for the design and construction of aircraft as the Sopwith Aviation Company Ltd..

The new company had a difficult start, but with the outbreak of the First World War in 1914 business was soon booming thanks to a number of highly successful military aircraft. Best known are the 1½-Strutter, the Pup, Triplane and last but not least the Camel. When the war ended, things changed dramatically with an enormous decline in aircraft needed. The company had earned enough money to survive this period, but shortly after the war the government charged punitive and excessive so-called anti-profiteering taxes. The company was forced to dissolve itself in 1920. However, a fresh restart was made with new capital.

Sopwith; a detailed type-by type review

Although the title of this book suggests it only gives a description of the Triplane fighter, details are given here on all important Sopwith aircraft since very little has been published on this recently. Before Sopwith started to manufacture its own types the company had modified a Wright biplane (manufactured by the British Howard Wright) and fitted it with a 50 hp Gnome engine. Later, this was even completely rebuilt fitted with a 70 hp Gnome engine from a Blériot. Also a hybrid biplane with a closed fuselage based on the earlier Wright was built.

The first completely new design from the company was the threeseat tractor biplane of 1913 with a 80 hp Gnome engine. It featured three large celluloid windows for the two passengers sitting in front of the pilot. Three were built. Three more modified examples on floats were built, powered by a 100 hp Anzani engine.

Second type built in 1913 was a small two-seat biplane flying boat known as the Bat Boat. The first one was powered by a 6-cylinder 90 hp Austro-Daimler engine. It was soon wrecked, but another two were supplied to the British Admiralty; later to be followed by an improved amphibian version known as Bat Boat II with a 200 hp engine.

The next design was the Tabloid, a single seat high-speed biplane that became world famous when it gained, as version on floats, the 1st place at the Schneider Trophy contest of 1914 at Monaco. Pilot on this occasion was Howard Pixton who convincingly won with his 100 hp Gnome powered racer. More Tabloids were constructed as a landplane with a wheel undercarriage. The Tabloid was the first Sopwith airplane built in substantial numbers with a total of 137 manufactured in various sub types. The Tabloid was further developed into the military types Pup (originally known as ‘Scout’) and the Baby seaplane.