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Regional Aircraft/Corporate-General Aviation

Regional Aircraft/Corporate-General Aviation. Sudarshan Kumar Associate Professor Aerospace Engineering Department IIT Bombay, India. Regional airline. A regional airline is a small airline designed to fly up to 100 passengers on short-haul flights,

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Regional Aircraft/Corporate-General Aviation

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  1. Regional Aircraft/Corporate-General Aviation Sudarshan Kumar Associate Professor Aerospace Engineering Department IIT Bombay, India

  2. Regional airline • A 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 airlines • that are either contracted • subsidiaries of the larger airlines.

  3. General features • Regional aircrafts are 40-60 % less fuel efficient than their larger, narrow and wide body counterparts employed for long range • Regional jets are 10-60 % less fuel efficient than turboprops • The 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

  4. Why 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 aircrafts • Slowly new aircrafts models emerged, • In the post-war era • Douglas DC-3s, • De Havilland Dragon Rapider • Convair 440, • Douglas DC-6 • Vickers Viscount

  6. Duglas DC-3 • Developed in 1935 • Fixed wing propeller driven aircraft • More than 16000 planes were built and flown • Early 1950s’ turboprop conversions • It is still being operated by some revenue and cargo companies • Technical specifications: • 1200 bhp radial piston engines (PT6 engine variants) • Later P&W engines used with 433 – 1447 kW shaft power • Rolls Royce engines (RB 53 Dart) 1800 bhp shaft power

  7. Bombardier Dash 8 • Two engines, medium range turboprop airliner • Over 1000 planes have been ordered • STOL performance • Improved cruise performance • Low operational costs • Engine (P&W – PW100) • Seating capacity 39 – 80 with a range of engines • Can operate from smaller runways (910 m)

  8. Regional jet

  9. Regional jet • Although more expensive that the turboprop • Favored for routed not suitable for turboprops • Lower maintenance costs of turbojet engines • 30% more fuel consumption

  10. According to Bombardier marketing, the aircraft breaks even • For about 1/3rd of its seats filled • Or 1/4 with more closely spaced seats • Making it particularly attractive on routes with varying passenger numbers • For 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 35-36 seats (~55% breakeven load factor). • For most short-haul routes (< 500 km), • time spent on taxiing, • takeoff • Landing • This 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 range • Bombardier commercial aircraft president Gary Scott has affirmed that • By 2013-2014 we are planning to offer a stretched version of the Q400 turboprop.

  11. Indian regional jet

  12. Indian regional jet

  13. Indian regional jet (IRJ) • Jointly proposed by NAL and HAL in 2007 • 70 – 100 seater aircraft • Common platform for turbo prop and turbo fan engines • 95 % of the airframe and other systems same • The aircraft claimed to offer • 25% lower acquisition costs • 25% lower operating costs • 50% lower maintenance costs than existing turboprop regional aircraft. • Specifications: • Range: 2,500 km, Runway length: 900m • Aircraft length: 28.6m Wing-span: 29.4m • Service ceiling: 30,000 ft, Cruising speed: 300kt, • Noise level to meet Stage 4 criteria. Composite airframe • 60% lower emissions Ability to operate from ill equipped airfields • Cabin dimensions: Length - 3.01 m and height - 3.35 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

  14. ATR-72

  15. 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 wingspan • Adding more powerful engines • Increasing fuel capacity by approximately 10 percent. • The 72 was announced in 1986,[2] and made its maiden flight on 27 October 1988. • One year after that, Finnair became the first airline to put the plane into service • Since then, at least 408 ATR 72s have been delivered worldwide with orders pending on at least 28 more. • Design • Passengers 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 characteristics • Crew: 2 • Capacity: 68 to 74 passengers • Length: 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 PW127Fturboprops, 1,846 kW each • Performance • Cruise speed: 511 km/h Range: 1,324 km • Service ceiling: 7,620 m Takeoff Run at MTOW: 1,165 m (3,822 ft)

  16. Embraer jet

  17. Embraer- ERJ family • The aircraft ERJ 135-145 family is powered by two turbofan engines (Rolls-Royce AE 3007) • Thrust: 30 – 42 kN • Pressure ratio 20: 1 • Turbine inlet temperature: 1300 K • Thrust to weight ration : 5: 1 • Capacity 37 – 122 passengers • Sold around 1800 jets in last 15 years • Service ceiling: 11278 m • Cruise speed: 828 kmph • Range: 3200 km • The ERJ E-170-195 family employs GE CF34- 8E/10E engine series • Thrust: 63 – 89 kN thrust • Range – 4000 km • Cruise speed: 890 kmph • 80-122 passengers

  18. Energy efficiency and load factor EI = Energy intensity – energy consumed per ASK (available seat per km) EU = Energy usage- energy required per km a = load factor • EI– energy consumed per ASK • Constant for all the aircrafts • EU = Varies from one aircraft to another • Depends on • Technological advancement • Size • Mission • Propulsion system type • Operational efficiencies

  19. EU of regional aircraft and their yearly average

  20. EU of regional aircraft and their yearly average • EU of regional jets has improved with an annual rate of about 2 % per year • EU of turboprops has improved by ~1.5 % per year. • Although regional jets are ~ 50 % less efficient than turboprops • But 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 field • Technology developed for those engines is simply transferred to regional jets • Not much investment into the turboprops because of their limited application • regional transport • lower speed as compared to regional jets

  21. EU comparison of large and regional aircrafts Drastic decrease in the E indicates technological advancement due to demand for long distance travel

  22. Specific fuel consumption of Engines

  23. 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 jets • For smaller size the gap remains as efficiency of a system can not be improved when size of the engine is reduced …e.g. regional transportation • Due 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 compressors • Turboprops are 10-30 % 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

  24. 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 components • Reduction in the component weight is offset by integration of new passenger facilities i.e. personal entrainment systems • For smaller engines, thrust to weight ratios are typical lower • Turboprops are quite poor because of high weight of engine components (e.g. Speed reduction gearbox; mechanisms to alter propeller pitch)

  25. Trends in structural efficiency

  26. Aerodynamic efficiencies

  27. Energy usage for various aircrafts

  28. Energy usage • EU for large aircrafts is approximately 1.6 times to that of EU,CR • For regional aircrafts, the number is app. 2.6 • For turboprops, it is approximately 2.5 times

  29. Operational sequence influence

  30. Ground Efficiencies

  31. Airborne efficiency

  32. Energy usage Vs ground and airborne efficiencies

  33. Operating costs

  34. Pilot salaries and fuel costs Pilot salaries (% of total cost) Fuel costs (% of total cost)

  35. Operational cost Vs Stage length

  36. Regional Daily flights distribution in 2002

  37. Comparison of fuel consumption Turboprop

  38. Propulsive efficiency

  39. Turboprops and Turbofans

  40. Why regional transport • For regional transport • Many hubs located around the many centers • Delhi, Mumbai, Bangalore, Chennai, Hyderabad • Distance ~ 600 km • Importance of connectivity

  41. Conclusions • Regional aircrafts have value of energy use 1.5 - 2 times greater than larger aircraft • The difference is due to operational sequence rather than technological sophistication • Regional 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 turboprops • Regional 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.

  42. References • Smirti and Hansen, “The effect of fuel prices on comparative aircraft costs,” National center of Excellence for Aviation Operations Research • Babikian et al., “The historical fuel efficiency characteristics of regional aircraft from technological, operational, and cost perspectives,” Journal of air transportation management, 8(6) 2002, 389-400. • ATR- Optimum choice for friendly environment, www.fc.fi/data/files/ATR_TheOptimumChoice.pdf • The green power of tomorrow, The latest generation turboprops, www.avantiair.com/.../The%20green%20power%20of%20tomorrow.pdf

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