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66-450: The de Havilland Canada DHC-7 , popularly known as the Dash 7 , is a turboprop -powered regional airliner with short take-off and landing (STOL) performance. Variants were built with 50–54 seats. It first flew in 1975 and remained in production until 1988 when the parent company, de Havilland Canada , was purchased by Boeing in 1986 and later sold to Bombardier . In 2006 Bombardier sold

132-400: A Pratt & Whitney Canada PT6 , and an under-speed governor on a Honeywell TPE331 . The turboprop is also distinguished from other kinds of turbine engine in that the fuel control unit is connected to the governor to help dictate power. To make the engine more compact, reverse airflow can be used. On a reverse-flow turboprop engine, the compressor intake is at the aft of the engine, and

198-424: A propelling nozzle . Air enters the intake and is compressed by the compressor. Fuel is then added to the compressed air in the combustor, where the fuel-air mixture then combusts . The hot combustion gases expand through the turbine stages, generating power at the point of exhaust. Some of the power generated by the turbine is used to drive the compressor and electric generator . The gases are then exhausted from

264-520: A bombing raid. In 1941, the engine was abandoned due to war, and the factory converted to conventional engine production. The first mention of turboprop engines in the general public press was in the February 1944 issue of the British aviation publication Flight , which included a detailed cutaway drawing of what a possible future turboprop engine could look like. The drawing was very close to what

330-444: A full load of passengers, the ability to fly 700 nautical miles (1296km), or a range of 805 statute miles. With new noise restrictions coming into effect throughout the 1970s, an aircraft tailored for this role would also have to be very quiet. Propeller noise is a factor of blade length and chord and the speed at which it rotates. To meet these new regulations, the new design used much larger (oversized) propellers geared to rotate at

396-442: A governor, and overspeed governor, and a fuel-topping governor. The governor works in much the same way a reciprocating engine propeller governor works, though a turboprop governor may incorporate beta control valve or beta lift rod for beta operation and is typically located in the 12 o'clock position. There are also other governors that are included in addition depending on the model, such as an overspeed and fuel topping governor on

462-543: A high-performance STOL operation were generally small and well served by the Twin Otters; had an airport needed a larger plane to serve its customer base, they would have built a longer runway. One exception to this was operations at London City Airport (LCY), which upon opening in 1987, was capable of handling few other aircraft types besides the Dash 7 due to its relatively short runway and steep approach. The runway at LCY

528-407: A lower speed than is normally designed. Much of the problem sound from a typical propeller is generated at the tips of the blades which are rotating at or just beneath the speed of sound. By using oversize propeller blades, there is no need to have the blade tip reaching near the speed of sound, and the rotating speed can therefore be reduced without sacrificing thrust. In reducing the speed, this noise

594-410: A mode typically consisting of zero to negative thrust, is used for all ground operations aside from takeoff. The Beta mode is further broken down into 2 additional modes, Beta for taxi and Beta plus power. Beta for taxi as the name implies is used for taxi operations and consists of all pitch ranges from the lowest alpha range pitch, all the way down to zero pitch, producing very little to zero-thrust and

660-491: A particular US air carrier conducted to determine predictors of an unstable approach based on conditions at 500 feet (150 m) AGL , has shown that factors with the highest correlation were, in order: A go-around is a relatively rare maneuver for most commercial pilots. On average, a short-haul pilot may make a go-around once or twice a year, and a long-haul pilot may make one every 2 to 3 years. Going around carries risks which include: A baulked landing or rejected landing

726-581: A small amount of air by a large degree, a low disc loading (thrust per unit disc area) increases the aircraft's energy efficiency , and this reduces the fuel use. Propellers work well until the flight speed of the aircraft is high enough that the airflow past the blade tips reaches the speed of sound. Beyond that speed, the proportion of the power that drives the propeller that is converted to propeller thrust falls dramatically. For this reason turboprop engines are not commonly used on aircraft that fly faster than 0.6–0.7 Mach , with some exceptions such as

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792-552: A switch to a fuselage with a circular cross-section), landing gear that folded forward into the inner engine nacelles, and a large T-tail intended to keep the elevator clear of the propwash during take-off (the Twin Otter's empennage was a cruciform arrangement). The Twin Otter incorporated " flaperons " that drooped the ailerons as part of the flaps, but these were not included in the Dash 7 due to weight and complexity. Instead,

858-591: A test-bed not intended for production. It first flew on 20 September 1945. From their experience with the Trent, Rolls-Royce developed the Rolls-Royce Clyde , the first turboprop engine to receive a type certificate for military and civil use, and the Dart , which became one of the most reliable turboprop engines ever built. Dart production continued for more than fifty years. The Dart-powered Vickers Viscount

924-610: A total of 19 Dash 7 aircraft (all variants) remain in service. The British Antarctic Survey operates a single Dash 7 in support of its research programme in Antarctica . The aircraft undertakes regular shuttle flights between either Stanley on the Falkland Islands , or Punta Arenas, Chile , and the Rothera Research Station on Adelaide Island . It also operates to and from the ice runway at

990-427: A wave-off were not initiated and the aircraft were not arrested, it would not have enough power and/or runway to fly off the carrier safely. Many airlines and aircraft operators state a list of conditions that must be satisfied so that a safe landing can be carried out. If one or more of these conditions cannot be satisfied then a go-around should be considered in some cases and must be carried out in others. This list

1056-408: Is an unofficial term that usually refer to a very late go-around, initiated when the when the aircraft is below the prescribed Decision Height or Minimum Descent Altitude or even when the aircraft has touched down. A baulked landing is considered a high risk go-around as the aircraft is typically in a low energy state with low altitude, idle thrust and decelerating airspeed. Additionally, as the aircraft

1122-413: Is between 70 and 85 knots. On touchdown, through "squat switches" in the main gear, the flaps automatically retract to the 25° position, thus reducing lift once on the runway and producing better braking performance. The flaps also retract to 25° when engine power is increased during a go-around procedure. The four-engine layout aids lift at low speeds due to the wide span of the propellers blowing air over

1188-489: Is coupled to the turbine through a reduction gear that converts the high RPM /low torque output to low RPM/high torque. This can be of two primary designs, free-turbine and fixed. A free-turbine turboshaft found on the Pratt & Whitney Canada PT6 , where the gas generator is not connected to the propeller. This allows for propeller strike or similar damage to occur without damaging the gas generator and allowing for only

1254-537: Is not an emergency, and may be necessary for a number of reasons. Some of those include; unstable approach, unable to land in the touchdown zone, not in correct configuration, directed by ATC, obstacle on the runway (aircraft, vehicle, animal), or aircraft controllability issues. Half of commercial jet crashes between 2012 through 2021 occurred during the approach, landing and go-around flight phases. In 2011, 68% (63) of accidents in commercial aviation occurred during these phases of flight. The lack of go-around decision

1320-459: Is reduced substantially. The Dash 7 often landed at only 900 rpm, and took off at only 1,210 rpm. In other respects, the new DHC-7 was essentially a larger, four-engine version of the Twin Otter: the general layout remained similar, with a high aspect ratio , high-mounted wing, and similar details of the cockpit and nose profile. Changes included the addition of cabin pressurization (requiring

1386-545: Is still used even for modern airliners , though they often do not use traditional traffic patterns/circuits for landing, instead using an airport-specific go-around procedure. Initiation of a go-around may be either ordered by air traffic control (normally the local or tower controller in a controlled field) or initiated by the pilot in command of the aircraft for a variety of reasons, such as an unstabilised approach, improperly executed landing ("bounce"), mechanical issue, sudden wind change, unsafe flight condition, or traffic on

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1452-407: Is that it can also be used to generate reverse thrust to reduce stopping distance on the runway. Additionally, in the event of an engine failure, the propeller can be feathered , thus minimizing the drag of the non-functioning propeller. While the power turbine may be integral with the gas generator section, many turboprops today feature a free power turbine on a separate coaxial shaft. This enables

1518-413: Is the leading risk factor in approach and landing accidents, and it is also the primary cause of runway excursions during landing. Yet, only an estimated 3–5% of unstabilised approaches lead to a go-around. One in ten go-around reports record a potentially hazardous go-around outcome, including exceeded aircraft performance limits or fuel endurance. A study by Embry–Riddle Aeronautical University on

1584-421: Is typically accessed by moving the power lever to a beta for taxi range. Beta plus power is a reverse range and produces negative thrust, often used for landing on short runways where the aircraft would need to rapidly slow down, as well as backing operations and is accessed by moving the power lever below the beta for taxi range. Due to the pilot not being able to see out of the rear of the aircraft for backing and

1650-446: Is usually written in airline or manufacturer's operations manual which must be approved by the relevant aviation authority. The operator's list of conditions allows pilots to use their individual judgment outside of this scope. When the pilot is instructed or decides to go around, the pilot applies full thrust or a predetermined TOGA (Takeoff and Go Around) thrust to the engine(s), adopts an appropriate climb attitude and airspeed, raises

1716-665: The Fokker F27 , Fairchild F-27 , Convair 580 , Convair 600 , and Hawker Siddeley 748 . The de Havilland Canada company personnel felt they could compete with these designs in a roundabout way. With their excellent STOL performance, their designs could fly into smaller airports located in city centres and smaller, outlying, more austere airports having runways that the other aircraft could not easily use (unpaved, unimproved). The original specification called for an aircraft that could carry 40 passengers and operating from runways only 2,000 ft long (610 m), and designed for, with

1782-634: The P-3 Orion , and the C-130 Hercules military transport aircraft. The first turbine-powered, shaft-driven helicopter was the Kaman K-225 , a development of Charles Kaman 's K-125 synchropter , which used a Boeing T50 turboshaft engine to power it on 11 December 1951. December 1963 saw the first delivery of Pratt & Whitney Canada's PT6 turboprop engine for the then Beechcraft 87, soon to become Beechcraft King Air . 1964 saw

1848-841: The Piper Meridian , Socata TBM , Pilatus PC-12 , Piaggio P.180 Avanti , Beechcraft King Air and Super King Air . In April 2017, there were 14,311 business turboprops in the worldwide fleet. Between 2012 and 2016, the ATSB observed 417 events with turboprop aircraft, 83 per year, over 1.4 million flight hours: 2.2 per 10,000 hours. Three were "high risk" involving engine malfunction and unplanned landing in single‑engine Cessna 208 Caravans , four "medium risk" and 96% "low risk". Two occurrences resulted in minor injuries due to engine malfunction and terrain collision in agricultural aircraft and five accidents involved aerial work: four in agriculture and one in an air ambulance . Jane's All

1914-496: The San Juan Mountains of southwest Colorado with this mountain airport having an airfield elevation of 9,078 feet thus making it one of the highest airports in the U.S. Kapalua Airport on the island of Maui , Hawaii was built by Hawaiian Airlines with a 3000-foot runway, specifically for Dash 7 operations. Scheduled passenger flights with new Dash 7 turboprops began on March 1, 1987. In 1993, this private airport

1980-606: The Sky Blu conducting coastal pollution and ice patrols across the Canadian Arctic. Data from Jane's All The World's Aircraft 1982–83 General characteristics Performance Related development Aircraft of comparable role, configuration, and era Related lists Turboprop A turboprop is a turbine engine that drives an aircraft propeller . A turboprop consists of an intake , reduction gearbox , compressor , combustor , turbine , and

2046-614: The Tupolev Tu-114 can reach 470 kn (870 km/h; 540 mph). Large military aircraft , like the Tupolev Tu-95 , and civil aircraft , such as the Lockheed L-188 Electra , were also turboprop powered. The Airbus A400M is powered by four Europrop TP400 engines, which are the second most powerful turboprop engines ever produced, after the 11 MW (15,000 hp) Kuznetsov NK-12 . In 2017,

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2112-403: The Tupolev Tu-95 . However, propfan engines, which are very similar to turboprop engines, can cruise at flight speeds approaching 0.75 Mach. To maintain propeller efficiency across a wide range of airspeeds, turboprops use constant-speed (variable-pitch) propellers. The blades of a constant-speed propeller increase their pitch as aircraft speed increases. Another benefit of this type of propeller

2178-438: The landing gear when the airplane has achieved a positive climb rate, retracts the flaps as necessary, follows the instructions of the control tower (in controlled airspace), and typically climbs into the traffic pattern or follows the published go-around procedure for another approach. Otherwise, the pilot may elect to divert to an alternate airport or wait while circling over the landing airport for some time, especially if

2244-498: The type certificate for the aircraft design to Victoria -based manufacturer Viking Air . In the 1960s, de Havilland Canada was already well known worldwide for their series of high-performance STOL aircraft, notably the very popular DHC-2 Beaver and DHC-6 Twin Otter . However, these aircraft were generally fairly small and served outlying routes, as opposed to the busier regional airliner routes which were already well served by larger, higher-performance turboprop aircraft such as

2310-635: The CF designation CC-132 and were delivered to 412 Transport Squadron at Canadian Forces Base Lahr , in West Germany . The United States Army operates several Dash 7 aircraft as surveillance platforms with the designation EO-5C (RC-7B before 2004) under the Airborne Reconnaissance Low program. Transport Canada operates a single DHC-7-150IR aircraft to conduct maritime surveillance, pollution monitoring, and ice patrols as part of

2376-564: The DHC-7-102 passenger version and -103 combi with an enlarged cargo door. These were followed by the Series 110 which met British CAA requirements, including the -110 and -111, and finally the Series 150 which included additional fuel capacity and an improved interior in the -150 and -151. Plans were made for a Series 200 with the new PT6A-50/7 engines which improved hot-and-high power, but these plans were shelved when Boeing ended production of

2442-533: The Soviet Union had the technology to create the airframe for a jet-powered strategic bomber comparable to Boeing's B-52 Stratofortress , they instead produced the Tupolev Tu-95 Bear, powered with four Kuznetsov NK-12 turboprops, mated to eight contra-rotating propellers (two per nacelle) with supersonic tip speeds to achieve maximum cruise speeds in excess of 575 mph, faster than many of

2508-621: The Transport Canada National Aerial Surveillance Program. The aircraft's home base is Ottawa, Ontario . During the summer, this aircraft conducts patrols throughout the Canadian Arctic, Alaska, and Greenland. During the fall and winter, this aircraft conducts patrols of the Great Lakes and east or west coasts of Canada as required. The design of a much more "conventional" twin-engine design commenced at de Havilland in 1978, resulting in

2574-454: The World's Aircraft . 2005–2006. Go-around The term arises from the traditional use of traffic patterns at airfields . A landing aircraft will first join the traffic pattern/circuit and prepare for landing. If for some reason, the pilot decides not to land, the pilot can simply fly back up to traffic pattern altitude/circuit height, and complete another circuit. The term "go-around"

2640-420: The additional expansion in the turbine system, the residual energy in the exhaust jet is low. Consequently, the exhaust jet produces about 10% of the total thrust. A higher proportion of the thrust comes from the propeller at low speeds and less at higher speeds. Turboprops have bypass ratios of 50–100, although the propulsion airflow is less clearly defined for propellers than for fans. The propeller

2706-415: The ailerons were reduced in size to allow more flap area, and were augmented with two sets of roll spoilers, or " spoilerons ". The inboard roll spoilers operate at all speeds. while the outboard roll spoilers only operate at speeds less than 130 KIAS to allow for more roll control at slower speeds. Upon touchdown, both the inboard and outboard roll spoilers extend in unison to aid in destroying lift created by

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2772-414: The amount of debris reverse stirs up, manufacturers will often limit the speeds beta plus power may be used and restrict its use on unimproved runways. Feathering of these propellers is performed by the propeller control lever. The constant-speed propeller is distinguished from the reciprocating engine constant-speed propeller by the control system. The turboprop system consists of 3 propeller governors ,

2838-492: The design. The mixture of features on the Dash 7 met with limited commercial success. Most commuter airline turboprop operators used the aircraft as feeder liners into large airports, where the STOL performance was not considered important. In comparison to other feeder liners, the Dash 7's four engines required twice the maintenance of a twin-engine model, thereby driving up operational costs. Finally, those airports that did require

2904-407: The exhaust is situated forward, reducing the distance between the turbine and the propeller. Unlike the small-diameter fans used in turbofan engines, the propeller has a large diameter that lets it accelerate a large volume of air. This permits a lower airstream velocity for a given amount of thrust. Since it is more efficient at low speeds to accelerate a large amount of air by a small degree than

2970-403: The extremely popular Dash 8 . The DHC-7 production line eventually delivered 113, of which six have been lost and one scrapped. Many of the rest remain in service. The American band Wilco released a song called "Dash 7" on their 1995 album A.M. The de Havilland Canada DHC-7 has been involved in six accidents (and 10 incidents overall) with a total of 68 fatalities. As of September 2024,

3036-499: The first jet aircraft and comparable to jet cruising speeds for most missions. The Bear would serve as their most successful long-range combat and surveillance aircraft and symbol of Soviet power projection through to the end of the 20th century. The USA used turboprop engines with contra-rotating propellers, such as the Allison T40 , on some experimental aircraft during the 1950s. The T40-powered Convair R3Y Tradewind flying-boat

3102-564: The first deliveries of the Garrett AiResearch TPE331 , (now owned by Honeywell Aerospace ) on the Mitsubishi MU-2 , making it the fastest turboprop aircraft for that year. In contrast to turbofans , turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low. Modern turboprop airliners operate at nearly

3168-465: The future Rolls-Royce Trent would look like. The first British turboprop engine was the Rolls-Royce RB.50 Trent , a converted Derwent II fitted with reduction gear and a Rotol 7 ft 11 in (2.41 m) five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 — the sole "Trent-Meteor" — which thus became the world's first turboprop-powered aircraft to fly, albeit as

3234-534: The go-around was initiated by bad weather. Many modern aircraft, such as most Boeing and Airbus aircraft, have autothrottle /autothrust systems that will set go-around thrust if they are engaged. On other aircraft, the pilot configures manually for a go-around. In a typical small aircraft, such as those found in general aviation , this might involve: Go-arounds occur with an average rate of 1–3 per 1000 approaches. Go-around rates vary between different aircraft operators and operational environments. A go-around

3300-619: The most widespread turboprop airliners in service were the ATR 42 / 72 (950 aircraft), Bombardier Q400 (506), De Havilland Canada Dash 8 -100/200/300 (374), Beechcraft 1900 (328), de Havilland Canada DHC-6 Twin Otter (270), Saab 340 (225). Less widespread and older airliners include the BAe Jetstream 31 , Embraer EMB 120 Brasilia , Fairchild Swearingen Metroliner , Dornier 328 , Saab 2000 , Xian MA60 , MA600 and MA700 , Fokker 27 and 50 . Turboprop business aircraft include

3366-493: The power section (turbine and gearbox) to be removed and replaced in such an event, and also allows for less stress on the start during engine ground starts. Whereas a fixed shaft has the gearbox and gas generator connected, such as on the Honeywell TPE331 . The propeller itself is normally a constant-speed (variable pitch) propeller type similar to that used with larger aircraft reciprocating engines , except that

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3432-534: The propeller to rotate freely, independent of compressor speed. Alan Arnold Griffith had published a paper on compressor design in 1926. Subsequent work at the Royal Aircraft Establishment investigated axial compressor-based designs that would drive a propeller. From 1929, Frank Whittle began work on centrifugal compressor-based designs that would use all the gas power produced by the engine for jet thrust. The world's first turboprop

3498-403: The propeller-control requirements are very different. Due to the turbine engine's slow response to power inputs, particularly at low speeds, the propeller has a greater range of selected travel in order to make rapid thrust changes, notably for taxi, reverse, and other ground operations. The propeller has 2 modes, Alpha and Beta. Alpha is the mode for all flight operations including takeoff. Beta,

3564-747: The prototype first flew on March 27, 1975. Testing went smoothly, and the first delivery took place to Rocky Mountain Airways on February 3, 1978. The Dash 7 enabled Rocky Mountain Airways to operate scheduled passenger air service from Denver into the Avon STOLport in Colorado which was controlled by the airline. The Avon STOLport was located in a mountain valley in close proximity to the Vail, CO ski resort. Another close-in ski resort airfield served by Rocky Mountain Airways with Dash 7 flights from Denver

3630-447: The runway. In naval aviation , the term wave-off is used instead of go-around. When touching down on an aircraft carrier , a pilot always initiates a wave-off by applying full thrust as a fail-safe measure. If the plane's tail hook fails to catch any of the arrestor cables (known as a (deck) "bolter" ) the aircraft can climb again. If the tailhook catches a cable, the aircraft will stop in short order regardless. Conversely, if

3696-592: The same speed as small regional jet airliners but burn two-thirds of the fuel per passenger. Compared to piston engines, their greater power-to-weight ratio (which allows for shorter takeoffs) and reliability can offset their higher initial cost, maintenance and fuel consumption. As jet fuel can be easier to obtain than avgas in remote areas, turboprop-powered aircraft like the Cessna Caravan and Quest Kodiak are used as bush airplanes . Turboprop engines are generally used on small subsonic aircraft, but

3762-415: The turbine. In contrast to a turbojet or turbofan , the engine's exhaust gases do not provide enough power to create significant thrust, since almost all of the engine's power is used to drive the propeller. Exhaust thrust in a turboprop is sacrificed in favor of shaft power, which is obtained by extracting additional power (beyond that necessary to drive the compressor) from turbine expansion. Owing to

3828-431: The wing ("propwash"). When reverse thrust is selected on landing, the props reverse pitch, push air forward, and slow the aircraft very effectively along with the antiskid main wheel brakes. More importantly, if an engine fails, the asymmetric thrust is much less than on a twin-engine layout, thereby increasing safety and allowing for a lower minimum control speed with an engine inoperative. Development started in 1972 and

3894-419: The wing. Each wing also includes two ground spoilers which only extend on touchdown. Most of the trailing edge is spanned by a complex, double Fowler flap arrangement for high lift at low speed. During a typical STOL landing, flaps are selected to the 45° position, generating more lift and drag, thus allowing for steeper descents and lower approach speeds. Depending on weight, the V REF speed with flaps at 45°

3960-541: Was Steamboat Springs Airport in Colorado. With a relatively short runway length of 4,452 feet and an airfield elevation of 6,882 feet, the Dash 7 was well suited for operations from this airport located in the Rocky Mountains. Flying as Continental Express via a code sharing agreement with Continental Airlines , Rocky Mountain Airways also operated the Dash 7 into the Telluride Airport located in

4026-436: Was acquired by the state of Hawaii. One hundred Dash 7 turboprops were delivered by 1984, when the production line was put on hold in favour of the Dash 8 . Another 13 were delivered between 1984 and 1988, when the production lines were removed when Boeing bought the company. The last Dash 7 was bought by Tyrolean Airways . The original Series 100 represents the vast majority of the aircraft delivered, and came in two models;

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4092-573: Was designed by the Hungarian mechanical engineer György Jendrassik . Jendrassik published a turboprop idea in 1928, and on 12 March 1929 he patented his invention. In 1938, he built a small-scale (100 Hp; 74.6 kW) experimental gas turbine. The larger Jendrassik Cs-1 , with a predicted output of 1,000 bhp, was produced and tested at the Ganz Works in Budapest between 1937 and 1941. It

4158-467: Was of axial-flow design with 15 compressor and 7 turbine stages, annular combustion chamber. First run in 1940, combustion problems limited its output to 400 bhp. Two Jendrassik Cs-1s were the engines for the world's first turboprop aircraft – the Varga RMI-1 X/H . This was a Hungarian fighter-bomber of WWII which had one model completed, but before its first flight it was destroyed in

4224-714: Was operated by the U.S. Navy for a short time. The first American turboprop engine was the General Electric XT31 , first used in the experimental Consolidated Vultee XP-81 . The XP-81 first flew in December 1945, the first aircraft to use a combination of turboprop and turbojet power. The technology of Allison's earlier T38 design evolved into the Allison T56 , used to power the Lockheed Electra airliner, its military maritime patrol derivative

4290-633: Was subsequently lengthened, and the approach angle reduced somewhat and since accepts airliners such as the Airbus A220 , Airbus A318 , British Aerospace BAe 146 and Embraer 190 types. Noise criteria remain strict in comparison with other international airports. The Dash 7 also gained a number of military orders. The first of these was for two aircraft for the Canadian Armed Forces , which needed them to transport high-ranking passengers and freight around Europe. These aircraft received

4356-603: Was the first turboprop aircraft of any kind to go into production and sold in large numbers. It was also the first four-engined turboprop. Its first flight was on 16 July 1948. The world's first single engined turboprop aircraft was the Armstrong Siddeley Mamba -powered Boulton Paul Balliol , which first flew on 24 March 1948. The Soviet Union built on German World War II turboprop preliminary design work by Junkers Motorenwerke, while BMW, Heinkel-Hirth and Daimler-Benz also worked on projected designs. While

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