Leadership in Energy and Environmental Design
Leadership in Energy and Environmental Design is one of the most popular green building certification programs used worldwide. Developed by the non-profit U. S. Green Building Council it includes a set of rating systems for the design, construction and maintenance of green buildings and neighborhoods that aims to help building owners and operators be environmentally responsible and use resources efficiently. Development of LEED began in 1993, spearheaded by Natural Resources Defense Council senior scientist Robert K. Watson; as founding chairman of the LEED Steering Committee, Watson led a broad-based consensus process until 2007, bringing together non-profit organizations, government agencies, engineers, builders, product manufacturers and other industry leaders. The LEED initiative was supported by a strong USGBC Board of Directors, chaired by Steven Winter from 1999 to 2003, active staff, including Nigel Howard. At that time, USGBC’s Senior Vice President of LEED, Scot Horst, became chair of the LEED Steering Committee before joining USGBC staff.
Early LEED committee members included USGBC co-founder Mike Italiano, architects Bill Reed and Sandy Mendler, builders Gerard Heiber and Myron Kibbe, engineer Richard Bourne. As interest in LEED grew, in 1996, engineers Tom Paladino and Lynn Barker co-chaired the newly formed LEED technical committee. From 1994 to 2015, LEED grew from one standard for new construction to a comprehensive system of interrelated standards covering aspects from the design and construction to the maintenance and operation of buildings. LEED has grown from six volunteers on one committee to 119,924 staff and professionals. LEED standards have been applied to 83,452 registered and certified LEED projects worldwide, covering around 13.8 billion square feet. Many U. S. federal agencies and states and local governments require or reward LEED certification. However, four states have banned the use of LEED in new public buildings, preferring other industry standards that the USGBC considers too lax. Unlike model building codes, such as the International Building Code, only members of the USGBC and specific "in-house" committees may add to, subtract from, or edit the standard, subject to an internal review process.
Proposals to modify the LEED standards are offered and publicly reviewed by USGBC's member organizations, which number 12,216. USGBC's Green Business Certification Inc. offers various accreditation to people who demonstrate knowledge of the LEED rating system, including LEED Accredited Professional, LEED Green Associate, since 2011, LEED Fellows, the highest designation for LEED professionals. GBCI certifies projects pursuing LEED. LEED has evolved since 1998 to more represent and incorporate emerging green building technologies; the pilot version, LEED New Construction v1.0, led to LEED NCv2.0, LEED NCv2.2 in 2005, LEED 2009 in 2009. LEED v4 was introduced in November, 2013; until October 31, 2016, new projects could choose between LEED 2009 and LEED v4. New projects registering after October 31, 2016 have been required to use LEED v4. LEED 2009 encompasses ten rating systems for the design and operation of buildings and neighborhoods. Five overarching categories correspond to the specialties available under the LEED professional program.
That suite consists of: Green Building Design & Construction LEED for New Construction LEED for Core & Shell LEED for Schools LEED for Retail: New Construction and Major Renovations LEED for HealthcareGreen Interior Design & Construction LEED for Commercial Interiors LEED for Retail: Commercial InteriorsGreen Building Operations & Maintenance LEED for Existing Buildings: Operations & MaintenanceGreen Neighborhood Development LEED for Neighborhood DevelopmentGreen Home Design and Construction LEED for Homes LEED forms the basis for other sustainability rating systems such as the Environmental Protection Agency's Labs21. To make it easier to follow LEED requirements, in 2009 USGBC helped BuildingGreen develop LEEDuser, a guide to the LEED certification process and applying for LEED credits written by professionals in the field. After four years of development, aligning credit across all LEED rating systems and weighing credits based on environmental priority, USGBC launched LEED v3, which consists of a new continuous development process, a new version of LEED Online, a revised third-party certification program and a new suite of rating systems known as LEED 2009.
Under LEED 2009, there are 100 possible base points distributed across six credit categories: "Sustainable Sites", "Water Efficiency", "Energy and Atmosphere", "Materials and Resources", "Indoor Environmental Quality", "Innovation in Design". Up to 10 additional points may be earned: four additional points may be received for Regional Priority Credits, six additional points for Innovation in Design. Buildings can qualify for four levels of certification: Certified: 40–49 points Silver: 50-59 points Gold: 60-79 points Platinum: 80 points and above The LEED 2009 performance credit system aims to allocate points "based on the potential environmental impacts and human benefits of each credit." These are weighed using the environmental impact categories of the United States Environmental Protection Agency's Tools for the Reduction and Assessment of Chemical and Other Environmental Impacts. and the environmental-impact weighting
A fighter aircraft is a military aircraft designed for air-to-air combat against other aircraft, as opposed to bombers and attack aircraft, whose main mission is to attack ground targets. The hallmarks of a fighter are its speed and small size relative to other combat aircraft. Many fighters have secondary ground-attack capabilities, some are designed as dual-purpose fighter-bombers; this may be for national security reasons, for advertising purposes, or other reasons. A fighter's main purpose is to establish air superiority over a battlefield. Since World War I, achieving and maintaining air superiority has been considered essential for victory in conventional warfare; the success or failure of a belligerent's efforts to gain air superiority hinges on several factors including the skill of its pilots, the tactical soundness of its doctrine for deploying its fighters, the numbers and performance of those fighters. Because of the importance of air superiority, since the early days of aerial combat armed forces have competed to develop technologically superior fighters and to deploy these fighters in greater numbers, fielding a viable fighter fleet consumes a substantial proportion of the defense budgets of modern armed forces.
The word "fighter" did not become the official English-language term for such aircraft until after World War I. In the British Royal Flying Corps and Royal Air Force these aircraft were referred to as "scouts" into the early 1920s; the U. S. Army called their fighters "pursuit" aircraft from 1916 until the late 1940s. In most languages a fighter aircraft is known as hunting aircraft. Exceptions include Russian, where a fighter is an "истребитель", meaning "exterminator", Hebrew where it is "matose krav"; as a part of military nomenclature, a letter is assigned to various types of aircraft to indicate their use, along with a number to indicate the specific aircraft. The letters used to designate a fighter differ in various countries – in the English-speaking world, "F" is now used to indicate a fighter, though when the pursuit designation was used in the US, they were "P" types. In Russia "I" was used, while the French continue to use "C". Although the term "fighter" specifies aircraft designed to shoot down other aircraft, such designs are also useful as multirole fighter-bombers, strike fighters, sometimes lighter, fighter-sized tactical ground-attack aircraft.
This has always been the case, for instance the Sopwith Camel and other "fighting scouts" of World War I performed a great deal of ground-attack work. In World War II, the USAAF and RAF favored fighters over dedicated light bombers or dive bombers, types such as the Republic P-47 Thunderbolt and Hawker Hurricane that were no longer competitive as aerial combat fighters were relegated to ground attack. Several aircraft, such as the F-111 and F-117, have received fighter designations though they had no fighter capability due to political or other reasons; the F-111B variant was intended for a fighter role with the U. S. Navy, but it was cancelled; this blurring follows the use of fighters from their earliest days for "attack" or "strike" operations against ground targets by means of strafing or dropping small bombs and incendiaries. Versatile multirole fighter-bombers such as the McDonnell Douglas F/A-18 Hornet are a less expensive option than having a range of specialized aircraft types; some of the most expensive fighters such as the US Grumman F-14 Tomcat, McDonnell Douglas F-15 Eagle, Lockheed Martin F-22 Raptor and Russian Sukhoi Su-27 were employed as all-weather interceptors as well as air superiority fighter aircraft, while developing air-to-ground roles late in their careers.
An interceptor is an aircraft intended to target bombers and so trades maneuverability for climb rate. Fighters were developed in World War I to deny enemy aircraft and dirigibles the ability to gather information by reconnaissance over the battlefield. Early fighters were small and armed by standards, most were biplanes built with a wooden frame covered with fabric, a maximum airspeed of about 100 mph; as control of the airspace over armies became important, all of the major powers developed fighters to support their military operations. Between the wars, wood was replaced in part or whole by metal tubing, aluminium stressed skin structures began to predominate. On 15 August 1914, Miodrag Tomić encountered an enemy plane while conducting a reconnaissance flight over Austria-Hungary; the Austro-Hungarian aviator waved at Tomić, who waved back. The enemy pilot took a revolver and began shooting at Tomić's plane. Tomić fired back, he swerved away from the Austro-Hungarian plane and the two aircraft parted ways.
It was considered the first exchange of fire between aircraft in history. Within weeks, all Serbian and Austro-Hungarian aircraft were armed; the Serbians equipped their planes with 8-millimetre Schwarzlose MG M.07/12 machine guns, six 100-round boxes of ammunition and several bombs. By World War II, most fighters were all-metal monoplanes armed with batteries of machine guns or cannons and some were capable of speeds approaching 400 mph. Most fighters up to this point had one engine.
Canadian Forces Base Borden RCAF Station Borden, is a Canadian Forces base located in Ontario. The historic birthplace of the Royal Canadian Air Force, CFB Borden is home to the largest training wing in the Canadian Armed Forces; the base is run by Canadian Forces Support Training Group and reports to the Canadian Defence Academy in Kingston. At the height of the First World War, the Borden Military Camp opened at a location on a glacial moraine west of Barrie in 1916 to train units for the Canadian Expeditionary Force, it was named for former Minister of Militia. In May 1916, the Barrie and Collingwood companies of the 157th Battalion, CEF, under the command of Lieutenant-Colonel D. H. MacLaren, began construction of the camp. Camp Borden was selected in 1917 for a military aerodrome, becoming the first flying station of the Royal Flying Corps Canada. During the inter-war period, the aerodrome was used as the training location for the nascent Royal Canadian Air Force and was renamed RCAF Station Borden.
Camp Borden's training grounds were expanded in 1938 to house the Canadian Tank School. The Siskins were a RCAF aerobatic flying team, established in 1929 at Camp Borden. During the Second World War, both Camp Borden and RCAF Station Borden became the most important training facility in Canada, housing both army training and flight training, the latter under the British Commonwealth Air Training Plan; the BCATP's No. 1 Service Flying Training School was located here until 1946. Relief landing fields were located at Edenvale. A third landing field, known locally as Leach's Field, was operated by Camp Borden from the 1920s to the 1950s; the L-shaped airstrip was rudimentary. It was used for touch-and-go flying. During the Cold War, Borden's importance as an RCAF facility in Ontario declined in favour of CFB Trenton, CFB Uplands and CFB North Bay. However, its use as an army facility stayed consistent until 1970 when a major reorganization of the combat arms' schools resulted in the transfer of the Infantry School and Armoured School to CFB Gagetown in New Brunswick.
On the other hand, numerous "purple" schools were established or expanded from existing service training establishments, including the Canadian Forces School of Administration and Logistics, the School of Aerospace Ordnance Engineering and the Canadian Forces Health Service Training Centre. The February 1, 1968 unification of the RCAF with the Royal Canadian Navy and the Canadian Army resulted in the creation of the Canadian Forces; the military facilities consisting of Camp Borden and RCAF Station Borden were grouped under a new name, Canadian Forces Base Borden. The aerodrome was closed in 1970 and the base saw use as a regular and reserve training facility for Canadian Forces Land Force Command, as well as hosting various land-based training courses for Canadian Forces Air Command. In a 1990s reorganization of the Canadian Forces following the end of the Cold War, CFB Borden's air force training facilities were grouped under the name 16 Wing Borden; the eight surviving Royal Flying Corps hangars at the base have been designated a National Historic Site of Canada.
The Ontario Heritage Foundation, Ministry of Culture and Recreation erected a plaque in 1976. Camp Borden was established during the First World War as a major training centre of Canadian Expeditionary Force battalions; the Camp was opened by Sir Sam Hughes, Minister of Militia and Defence, on July 11, 1916, after two months of intensive building. This military reserve, comprising over twenty square miles, was soon occupied by some 32,000 troops. Training facilities were expanded in 1917 with the institution of an air training programme under the Royal Flying Corps and the construction of the first Canadian military aerodrome, regarded as the finest military aviation camp in North America. Following the armistice Camp Borden continued as an important army and air force centre and became one of the largest armed forces bases in Canada. Although an air force training base, CFB Borden is now a training base for several elements of the Canadian Forces: 2 Canadian Air Division's primary lodger unit, 16 Wing referred to as 16 Wing Borden, consists of 16 Wing Headquarters and three schools: Canadian Forces School of Aerospace Technology and Engineering and Air Command Academy.
The Canadian Army's Regular Force and Primary Reserve army units use a number of training schools and large portions of the base's 22,300 acres training area for manoeuvres. In addition to these specific environmental element commands, CFB Borden houses a variety of other purple trades training facilities and headquarters within the Canadian Forces, including a fire-fighting school, Military Police school, a chaplaincy school, the Canadian Forces Recruiting Group, medical and language schools, supports local cadet and reserve units; the Toronto Police Service's Emergency Task Force trains there occasionally. CFB Borden hosts the Blackdown Cadet Training Centre, a facility established for training army cadets; this facility has hosted air cadets and sea cadets since 2003, when the Borden Air Cadet Summer Training Centre was closed. CFB Borden's residential area houses one regulation-sized golf course. Circled Pine Golf Course opened in 1952; the course is open to
Armstrong Whitworth Siskin
The Armstrong Whitworth Siskin was a British biplane single-seat fighter aircraft of the 1920s produced by Armstrong Whitworth Aircraft. The Siskin was one of the first new RAF fighters to enter service after the First World War; the design was a development of the Siddeley-Deasy S. R.2 Siskin designed by Major F. M. Green of the Siddeley-Deasy Motor Car Company, to meet the requirements of RAF Specification Type 1 for a single-seat fighter powered by the promising ABC Dragonfly radial engine; the SR. 2 Siskin was a single-bay biplane of fabric construction. Its wings were of unequal span and the aircraft was fitted with a distinctive fixed conventional landing gear with long oleo strut shock absorbers carrying the axle, connected by radius rods to a pair of V-struts situated behind the axle; the Dragonfly engine was fitted in a streamlined cowling to reduce drag, with individual cooling channels for each engine cylinder. Two Vickers machine guns were mounted in the nose decking in front of the pilot.
The Siskin first flew in May 1919, powered by a Dragonfly engine delivering 270 hp, rather than the promised 320 hp. Despite the expectations piled on it, the Dragonfly proved to be a disaster, far less powerful than expected and unreliable, being prone to overheating and catastrophic vibration, that would cause crankshaft failure within a few hours. Despite the engine problems, the Siskin displayed good performance and handling, outmatching its Dragonfly-powered contemporaries. In 1919, Siddeley-Deasy merged with Armstrong Whitworth, with the aviation interests becoming Armstrong Whitworth Aircraft. Siddeley-Deasy had inherited the design of the RAF.8 fourteen-cylinder radial engine and its designer Sam D. Heron, by 1920 this engine, now known as the Jaguar, had been developed sufficiently to be a possible replacement for the Dragonfly. One of the prototype Siskins was fitted with a Jaguar, flying in this form on 20 March 1921. In 1922 Air Ministry Specification 14/22 was issued for an all-metal single-seat high performance landplane and one Jaguar-powered prototype was ordered from Armstrong Whitworth.
As well as re-engining with the Jaguar, Major Green redesigned the Siskin with an all-metal structure, as the Siskin III. The change from wood to metal construction was a requirement of the Air Ministry war production plan which would use the motor car industry for aircraft production, something which would not have been possible using wood; the all-metal Siskin was the start of a general transition to metal for military aircraft to enable a rapid increase in aircraft production when required to meet wartime demand. A contract for three production aircraft was placed on 13 October 1922 with a further six ordered on 26 January 1923 including one as a prototype of a two-seat variant; the Siskin III first flew on 7 May 1923, with first deliveries to the RAF taking place in January 1924. The fighter was the first all-metal fighter in the British Royal Air Force. Following the order from the RAF, Romania ordered 65 aircraft but they were cancelled following a crash on takeoff at Whitley Abbey, Coventry, on 18 February 1925 during acceptance tests.
The main production version was the Siskin IIIA ordered in 1926, powered with a Jaguar IV engine, but was re-engined with the supercharged Jaguar IVA engine. The supercharger, a novel idea at the time, had little effect on performance below 10,000 ft, but it improved speed and climb above that height. Following an evaluation of two Siskin IIIs the Royal Canadian Air Force ordered 12 IIIAs which were delivered between 1926 and 1931. With Armstrong-Whitworth busy building the Armstrong Whitworth Atlas some of the Siskin IIIA production was sub-contracted out to Blackburn, Bristol and Vickers; the first Siskin IIIs were delivered to No. 41 Squadron RAF at RAF Northolt in May 1924 followed by No. 111 Squadron RAF. The Siskin III was popular in service, being manoeuvrable, although underpowered; the improved Siskin IIIA was first delivered to No. 111 Squadron in September 1926. The Siskin was used by 11 RAF squadrons; the last operational RAF Siskins were replaced in October 1932 by Bristol Bulldogs.
The Siskin presented exhibitions of flying at every RAF display from 1925 to 1931. The ski-equipped second Siskin II aircraft was sold to the Royal Swedish Air Force in 1925. Canada used the aircraft from 1926 until 1939. In 1926, the British Air Ministry sent two Siskin IIIs to Canada for testing by the Royal Canadian Air Force under winter flying conditions; the test pilot was Clennell H. Dickins; the Siskin was considered a modern type when it was acquired by RCAF, which purchased the Mark IIIA, used to equip the Fighter Flight at Camp Borden and Trenton. In 1937, the Flight became No. I Squadron and was transferred from Trenton to Calgary in August 1938. Siskin aircraft remained with this unit until the outbreak of the Second World War to be replaced by Hawker Hurricanes in 1939; the airframes were turned over to various technical establishments for use as instructional airframes. Like its RAF counterparts, in 1929, a three-plane Siskin air demonstration team was formed at Camp Borden, Ontario – the RCAF's first official flight demonstration team.
The aerobatic team put on popular formation displays from coast to coast. The Siskin was used as a successful racing aircraft, a Siskin V flown by Flight Lieutenant Barnard winning the 1925 Kings Cup Race at a speed of more than 151 mph. Siddeley Deasy S. R.2 Siskin – Prototype fighter aircraft built by Siddeley-Deasy and powered by Dragonfly engine. Three built. Siski
Air traffic control
Air traffic control is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through controlled airspace, can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions and expedite the flow of air traffic, provide information and other support for pilots. In some countries, ATC is operated by the military. To prevent collisions, ATC enforces traffic separation rules, which ensure each aircraft maintains a minimum amount of empty space around it at all times. Many aircraft have collision avoidance systems, which provide additional safety by warning pilots when other aircraft get too close. In many countries, ATC provides services to all private and commercial aircraft operating within its airspace. Depending on the type of flight and the class of airspace, ATC may issue instructions that pilots are required to obey, or advisories that pilots may, at their discretion, disregard; the pilot in command is the final authority for the safe operation of the aircraft and may, in an emergency, deviate from ATC instructions to the extent required to maintain safe operation of their aircraft.
Pursuant to requirements of the International Civil Aviation Organization, ATC operations are conducted either in the English language or the language used by the station on the ground. In practice, the native language for a region is used. In 1920, Croydon Airport, London was the first airport in the world to introduce air traffic control. In the United States, air traffic control developed three divisions; the first of air mail radio stations was created in 1922 after World War I when the U. S. Post Office began using techniques developed by the Army to direct and track the movements of reconnaissance aircraft. Over time, the AMRS morphed into flight service stations. Today's flight service stations do not issue control instructions, but provide pilots with many other flight related informational services, they do relay control instructions from ATC in areas where flight service is the only facility with radio or phone coverage. The first airport traffic control tower, regulating arrivals and surface movement of aircraft at a specific airport, opened in Cleveland in 1930.
Approach/departure control facilities were created after adoption of radar in the 1950s to monitor and control the busy airspace around larger airports. The first air route traffic control center, which directs the movement of aircraft between departure and destination was opened in Newark, NJ in 1935, followed in 1936 by Chicago and Cleveland; the primary method of controlling the immediate airport environment is visual observation from the airport control tower. The tower is a windowed structure located on the airport grounds. Air traffic controllers are responsible for the separation and efficient movement of aircraft and vehicles operating on the taxiways and runways of the airport itself, aircraft in the air near the airport 5 to 10 nautical miles depending on the airport procedures. Surveillance displays are available to controllers at larger airports to assist with controlling air traffic. Controllers may use a radar system called secondary surveillance radar for airborne traffic approaching and departing.
These displays include a map of the area, the position of various aircraft, data tags that include aircraft identification, speed and other information described in local procedures. In adverse weather conditions the tower controllers may use surface movement radar, surface movement guidance and control systems or advanced SMGCS to control traffic on the manoeuvring area; the areas of responsibility for tower controllers fall into three general operational disciplines: local control or air control, ground control, flight data / clearance delivery—other categories, such as Apron control or ground movement planner, may exist at busy airports. While each tower may have unique airport-specific procedures, such as multiple teams of controllers at major or complex airports with multiple runways, the following provides a general concept of the delegation of responsibilities within the tower environment. Remote and virtual tower is a system based on air traffic controllers being located somewhere other than at the local airport tower and still able to provide air traffic control services.
Displays for the air traffic controllers may be live video, synthetic images based on surveillance sensor data, or both. Ground control is responsible for the airport "movement" areas, as well as areas not released to the airlines or other users; this includes all taxiways, inactive runways, holding areas, some transitional aprons or intersections where aircraft arrive, having vacated the runway or departure gate. Exact areas and control responsibilities are defined in local documents and agreements at each airport. Any aircraft, vehicle, or person walking or working in these areas is required to have clearance from ground control; this is done via VHF/UHF radio, but there may be special cases where other procedures are used. Aircraft or vehicles without radios must respond to ATC instructions via aviation light signals or else be led by vehicles with radios. People working on the airport surface have a communications link through which they can communicate with ground control either by handheld radio or cell phone.
Ground control is vital to the smooth operation of the airport, because this position impacts th
Avro Canada CF-105 Arrow
The Avro Canada CF-105 Arrow known as the Avro Arrow, was a delta-winged interceptor aircraft designed and built by Avro Canada. The CF-105 held the promise of Mach 2 speeds at altitudes exceeding 50,000 feet and was intended to serve as the Royal Canadian Air Force's primary interceptor into the 1960s and beyond; the Arrow was the culmination of a series of design studies begun in 1953 that examined improved versions of the Avro Canada CF-100 Canuck. After considerable study, the RCAF selected a more powerful design, serious development began in March 1955; the aircraft was intended to be built directly from the production line, skipping the traditional hand-built prototype phase. The first Arrow Mk. I, RL-201, was rolled out to the public on 4 October 1957, the same day as the launch of Sputnik I. Flight testing began with RL-201 on 25 March 1958, the design demonstrated excellent handling and overall performance, reaching Mach 1.9 in level flight. Powered by the Pratt & Whitney J75, another three Mk.
1s were completed, RL-202, RL-203 and RL-204. The lighter and more powerful Orenda Iroquois engine was soon ready for testing, the first Mk. II with the Iroquois, RL-206, was ready for taxi testing in preparation for flight and acceptance tests by RCAF pilots by early 1959. On 20 February 1959, Prime Minister of Canada John Diefenbaker abruptly halted the development of the Arrow before the scheduled project review to evaluate the program could be held. Canada tried to sell the Arrow to the US and Britain. Two months the assembly line, tooling and existing airframes and engines were ordered to be destroyed; the cancellation was the topic of considerable political controversy at the time, the subsequent destruction of the aircraft in production remains a topic for debate among historians and industry pundits. "This action put Avro out of business and its skilled engineering and production personnel scattered..." In the post-Second World War period, the Soviet Union began developing a capable fleet of long-range bombers with the ability to deliver nuclear weapons across North America and Europe.
The main threat was principally from high-speed, high-altitude bombing runs launched from the Soviet Union travelling over the Arctic against military bases and built-up industrial centres in Canada and the United States. To counter this threat, Western countries developed interceptors that could engage and destroy these bombers before they reached their targets. A. V. Roe Canada Limited had been set up as a subsidiary of the Hawker Siddeley Group in 1945 handling repair and maintenance work for aircraft at Malton, Ontario Airport, today known as Toronto Pearson International Airport; the next year the company began the design of Canada's first jet fighter for the Royal Canadian Air Force, the Avro CF-100 Canuck all-weather interceptor. The Canuck underwent a lengthy and troubled prototype stage before entering service seven years in 1953, it went on to become one of the most enduring aircraft of its class, serving in a variety of roles until 1981. Recognizing that the delays that affected the development and deployment of the CF-100 could affect its successor, the fact that the Soviets were working on newer jet-powered bombers that would render the CF-100 ineffective, the RCAF began looking for a supersonic, missile-armed replacement for the Canuck before it had entered service.
In March 1952, the RCAF's Final Report of the All-Weather Interceptor Requirements Team was submitted to Avro Canada. Avro engineering had been considering supersonic issues at this point. Supersonic flight works in a different fashion and presents a number of new problems. One of the most critical, surprising, was the sudden onset of a new form of drag, known as wave drag; the effects of wave drag were so strong that engines of the era could not provide enough power to overcome it, leading to the concept of a "sound barrier". German research during the Second World War had shown the onset of wave drag was reduced by using airfoils that varied in curvature as as possible; this suggested the use of thinner airfoils with much longer chord than designers would have used on subsonic aircraft. These designs were impractical because they left little internal room in the wing for armament or fuel; the Germans discovered it was possible to "trick" the airflow into the same behaviour if a conventional thicker airfoil was used swept rearward at a sharp angle, creating a swept wing.
This provided many of the advantages of a thinner airfoil while retaining the internal space needed for strength and fuel storage. Another advantage was that the wings were clear of the supersonic shock wave generated by the nose of the aircraft; every fighter project in the postwar era applied the concept, which started appearing on production fighters in the late 1940s. Avro engineers explored swept-wing and tail modifications to the CF-100 known as the CF-103, which had proceeded to wooden mock-up stage; the CF-103 offered improved transonic performance with supersonic abilities in a dive. The basic CF-100 continued to improve through this period, the advantages were continually eroded; when a CF-100 broke the sound barrier on 18 December 1952, interest in the CF-103 waned. Another solution to the high-speed problem is the delta wing; the delta wing had many of the same advantages of the swept wing in terms of transonic and supersonic performance, but offered much more internal room and overall surface area.
This provided more room for fuel, an important consideration given the inefficient early jet engines of the era, the large wing area provided ample lift at high altitudes
The Vickers Viscount was a British medium-range turboprop airliner first flown in 1948 by Vickers-Armstrongs. A design requirement from the Brabazon Committee, it entered service in 1953 and was the first turboprop-powered airliner; the Viscount was well received by the public for its cabin conditions, which included pressurisation, reductions in vibration and noise, panoramic windows. It became one of the most profitable of the first post-war transport aircraft; the Viscount was a response to the Brabazon Committee's Type II design for a post-war small medium-range pressurised aircraft to fly less-travelled routes, carrying 24 passengers up to 1,750 mi at 200 mph. During discussions between the committee and Vickers' chief designer, Rex Pierson, Vickers advocated turboprop power; the committee was not convinced and split the specification into two types, the Type IIA using piston power, which led to the Airspeed Ambassador, the turboprop-powered Type IIB which Vickers was selected to develop in April 1945.
British European Airways was involved in the design and asked that the aircraft carry 32 passengers instead, but remained otherwise similar. The first design in June 1945 was based on the Viking with four turboprop engines and 24 seats and designated the VC-2 or Type 453. A double-bubble fuselage was proposed to give extra underfloor cargo space. Neither was pressurised but it was soon realised that for economical operation an altitude above 20,000 ft was needed, thus pressurisation was required. The decision for pressurisation resulted in the double-bubble and elliptical fuselage designs being abandoned. A circular cross-section variant was offered at the beginning of 1946; the resulting 28-seat VC-2 was financed by the Ministry of Supply with an order for two prototypes. But, before the contract was signed, the government asked for the capacity to be increased to 32; this stretched the fuselage increase from 65 ft 5 in to 74 ft 6 in and meant an increased wingspan of 89 ft. The contract for the aircraft to Air Ministry specification C.16/46 was signed on 9 March 1946 and Vickers allocated the designation Type 609 and the name Viceroy.
Although George Edwards had always favoured the 800 hp Rolls-Royce Dart other engines were considered, including the Armstrong Siddeley Mamba which the government specified for the two prototypes. The choice of the Mamba engine increased the weight but Vickers made sure the engine nacelle would fit either the Mamba or Dart. While the Dart progressed better in development, the government asked in August 1947 for the second prototype to be Dart-powered; the second prototype was named as the Viscount. The first prototype under construction was converted to the Dart as a 630 as well; the resulting Vickers Type 630 design was completed at Brooklands by chief designer Rex Pierson and his staff in 1945, a 32-seat airliner powered by four Dart engines for a cruising speed of 275 mph. An order for two prototypes was placed in March 1946, construction started in the company's Foxwarren Experimental Department. Viceroy after the viceroy of India, Lord Louis Mountbatten, the aircraft was renamed Viscount following India's independence in 1947.
There was work on replacing the Darts with the Mamba, but this was dropped by the time the prototypes were reaching completion. After Pierson's death in 1948, George Edwards took over as chief designer and assumed all technical control over the Viscount project; the prototype Type 630, registered G-AHRF, made its maiden flight from the grass airfield at Wisley on 16 July 1948, piloted by Joseph "Mutt" Summers, Vickers' chief test pilot. The design was considered too small and slow at 275 mph, making the per passenger operating costs too high for regular service, BEA had placed an order for 20 piston-engined Airspeed Ambassadors in 1947. Retrospectively commenting on Britain's aviation industry, Duncan Burn stated: "Had BEA committed itself to full support of the Viscount... it was quite that the smaller version would have gone into production... It was in a sense BEA's lack of enthusiasm for the 630 which made possible the success."Early flight trials, showed the qualities of a turboprop, resulting in a February 1949 order from the Ministry of Supply for a prototype of a stretched version with more powerful engines, the Type 700.
Meanwhile, the first prototype Type 630 was awarded a restricted Certificate of Airworthiness on 15 September 1949, followed by a full certificate on 27 July 1950, which allowed the aircraft to be placed into trial service with BEA on 29 July to familiarise the pilots and ground crew with the new aircraft. It flew scheduled flights between London and Paris, London and Edinburgh until 23 August 1950. 29 July 1950 flight between Northolt and Paris – Le Bourget Airport with 14 paying passengers was the first scheduled airline flight by any turbine-powered aircraft. The second prototype Viscount, the Type 663 testbed, had two Rolls-Royce Tay turbojet engines and first flew in RAF markings as serial VX217 at Wisley on 15 March 1950, it was demonstrated at the Farnborough SBAC Show in September and was used in the development of powered controls for the Valiant bomber. It saw use as a test bed by Boulton Paul Ltd for the development of electronic flight control systems; the designers went back to the drawing board and the aircraft emerged as the larger Type 700 with up to 48 passengers, a cruising speed of 308 mph.
The new prototype G-AMAV first flew from Brooklands on 28 August 1950, served as a development aircraft for