2 Regional airlineA regional airline is a small airline designed to fly up to 100 passengers on short-haul flights,Feeding larger carriers' hubs from small markets.This class of airliners are typically flown by the regional airlinesthat are either contractedsubsidiaries of the larger airlines.
3 General featuresRegional aircrafts are % less fuel efficient than their larger, narrow and wide body counterparts employed for long rangeRegional jets are % less fuel efficient than turbopropsThe difference in efficiency largely depends on the differences in operation rather than on technology.Operating costs per passenger are 2- 6 times higher for regional transport
5 History To keep these short routes economical, Airlines were generally unwilling to spend large amounts of money on new aircraft;Used available aircraftsSlowly new aircrafts models emerged,In the post-war eraDouglas DC-3s,De Havilland Dragon RapiderConvair 440,Douglas DC-6Vickers Viscount
7 Duglas DC-3 Developed in 1935 Fixed wing propeller driven aircraft More than planes were built and flownEarly 1950s’ turboprop conversionsIt is still being operated by some revenue and cargo companiesTechnical specifications:1200 bhp radial piston engines (PT6 engine variants)Later P&W engines used with 433 – 1447 kW shaft powerRolls Royce engines (RB 53 Dart) 1800 bhp shaft power
9 Bombardier Dash 8 Two engines, medium range turboprop airliner Over 1000 planes have been orderedSTOL performanceImproved cruise performanceLow operational costsEngine (P&W – PW100)Seating capacity 39 – 80 with a range of enginesCan operate from smaller runways (910 m)
11 Regional jet Although more expensive that the turboprop Favored for routed not suitable for turbopropsLower maintenance costs of turbojet engines30% more fuel consumption
12 According to Bombardier marketing, the aircraft breaks even For about 1/3rd of its seats filledOr 1/4 with more closely spaced seatsMaking it particularly attractive on routes with varying passenger numbersFor example, Island Air in Hawaii calculated that the use of a 50-seat Regional Jet would break even at 45 passenger seats compared to the Q400's seats (~55% breakeven load factor).For most short-haul routes (< 500 km),time spent on taxiing,takeoffLandingThis eliminates a competing jet's speed advantage.Q400's 414 mph (667 km/h) cruise speed approaches jet speeds,Short-haul airlines can easily replace a regional jet with a Q400 without changing their gate-to-gate schedules.Bombardier has singled out the Q400 for more aggressive marketing,Competes in the 90-seat market rangeBombardier commercial aircraft president Gary Scott has affirmed thatBy we are planning to offer a stretched version of the Q400 turboprop.
15 Indian regional jet (IRJ) Jointly proposed by NAL and HAL in 200770 – 100 seater aircraftCommon platform for turbo prop and turbo fan engines95 % of the airframe and other systems sameThe aircraft claimed to offer25% lower acquisition costs25% lower operating costs50% lower maintenance costs than existing turboprop regional aircraft.Specifications:Range: 2,500 km, Runway length: 900mAircraft length: 28.6m Wing-span: 29.4mService ceiling: 30,000 ft, Cruising speed: 300kt,Noise level to meet Stage 4 criteria. Composite airframe60% lower emissions Ability to operate from ill equipped airfieldsCabin dimensions: Length m and height m.Cargo version to have 25 m3 volume.Indigenous fly-by-wire control system, Open distributed modular avionics,Automatic dependence surveillance Broadcast navigation capabilities, and advanced displays
17 ATR 72 ATR 72 was developed from the ATR 42 To increase the seating capacity (48 to 78) by stretching the fuselage by 4.5 metres (15 ft)Increasing the wingspanAdding more powerful enginesIncreasing fuel capacity by approximately 10 percent.The 72 was announced in 1986, and made its maiden flight on 27 October 1988.One year after that, Finnair became the first airline to put the plane into serviceSince then, at least 408 ATR 72s have been delivered worldwide with orders pending on at least 28 more.DesignPassengers are boarded using the rear door (quite rare)The ATR aircraft does not have an auxiliary power unit (APU)"Hotel Mode") that stops the propeller on the #2 (right) engine, allowing the turbine to run and provide air and power to the aircraft without the propeller spinning.General characteristicsCrew: 2Capacity: 68 to 74 passengersLength: 27.17 m (89 ft 2 in) Wingspan: 27.05 m (88 ft 9 in)Height: 7.65 m (25 ft 1 in) Wing area: 61.00 m2 (656.6 sq ft)Aspect ratio: 12.0:1 Empty weight: 12,950 kg (28,550 lb)Max takeoff weight: 22,500 kg (49,604 lb) Powerplant: 2 × Pratt & Whitney PW127F turboprops, 1,846 kW eachPerformanceCruise speed: 511 km/h Range: 1,324 kmService ceiling: 7,620 m Takeoff Run at MTOW: 1,165 m (3,822 ft)
19 Embraer- ERJ familyThe aircraft ERJ family is powered by two turbofan engines (Rolls-Royce AE 3007)Thrust: 30 – 42 kNPressure ratio 20: 1Turbine inlet temperature: 1300 KThrust to weight ration : 5: 1Capacity 37 – 122 passengersSold around 1800 jets in last 15 yearsService ceiling: mCruise speed: kmphRange: kmThe ERJ E family employs GE CF34- 8E/10E engine seriesThrust: 63 – 89 kN thrustRange – kmCruise speed: 890 kmphpassengers
20 Energy efficiency and load factor EI = Energy intensity – energy consumed per ASK (available seat per km)EU = Energy usage- energy required per kma = load factorEI– energy consumed per ASKConstant for all the aircraftsEU = Varies from one aircraft to anotherDepends onTechnological advancementSizeMissionPropulsion system typeOperational efficiencies
21 EU of regional aircraft and their yearly average
22 EU of regional aircraft and their yearly average EU of regional jets has improved with an annual rate of about 2 % per yearEU of turboprops has improved by ~1.5 % per year.Although regional jets are ~ 50 % less efficient than turbopropsBut the technological advancement has helped in catching up with turboprops.Reason: More investment into improving the fuel efficiency of jet engines.Long range aircrafts most lucrative fieldTechnology developed for those engines is simply transferred to regional jetsNot much investment into the turboprops because of their limited applicationregional transportlower speed as compared to regional jets
23 EU comparison of large and regional aircrafts Drastic decrease in the E indicates technological advancement due to demand for long distance travel
25 Specific fuel consumption TSFC is 10-25% higher for regional jet as compared to large jet because of delay in implementation of new technology to regional jetsFor smaller size the gap remains as efficiency of a system can not be improved when size of the engine is reduced …e.g. regional transportationDue to limitation of engine size, smaller jet engines employ smaller lower pressure ratio engine and hence reduced efficiency.Hence lesser compressor stages and less efficient than centrifugal compressorsTurboprops are % more efficient than regional jets.Turboprops deliver 85% of the total thrust from propellers.Due to their ability to accelerate large amount of air at small speeds.Advantageous for takeoff, climb operation and low speed operation
26 Structural efficiencies 1% reduction in the gross weight reduces the specific fuel consumption by 0.25 – 0.75%.Despite availability of best materials i.e. composites, most of the aircrafts contains ~ 97% metallic with very few composite componentsReduction in the component weight is offset by integration of new passenger facilities i.e. personal entrainment systemsFor smaller engines, thrust to weight ratios are typical lowerTurboprops are quite poor because of high weight of engine components (e.g. Speed reduction gearbox; mechanisms to alter propeller pitch)
42 Why regional transport For regional transportMany hubs located around the many centersDelhi, Mumbai, Bangalore, Chennai, HyderabadDistance ~ 600 kmImportance of connectivity
43 ConclusionsRegional aircrafts have value of energy use times greater than larger aircraftThe difference is due to operational sequence rather than technological sophisticationRegional aircraft fly short lengths and spend large fraction of time in climbing to altitude than cruise.Turboprops have inherent advantage than regional jet as they can cruise efficiently at a much lower altitude than regional jets and at much lower speed.Fuel costs are~ 26% for larger aircrafts~ 20% for regional jets~ 13% for turbopropsRegional jets appear to be as good as turboprops because of their higher load factors.If strategies are evolved to increase the load factors in Turboprops, they are the best option of economical transport at regional levels.
44 ReferencesSmirti and Hansen, “The effect of fuel prices on comparative aircraft costs,” National center of Excellence for Aviation Operations ResearchBabikian et al., “The historical fuel efficiency characteristics of regional aircraft from technological, operational, and cost perspectives,” Journal of air transportation management, 8(6) 2002,ATR- Optimum choice for friendly environment,The green power of tomorrow, The latest generation turboprops,