Transcript ppt/12x - MRO India 2011

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,
• 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.
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
Why regional transport
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
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Douglas DC-3s,
De Havilland Dragon Rapider
Convair 440,
Douglas DC-6
Vickers Viscount
Duglas DC-3
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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
Bombardier Dash 8
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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)
Regional jet
Regional jet
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Although more expensive that the turboprop
Favored for routed not suitable for turboprops
Lower maintenance costs of turbojet engines
30% more fuel consumption
• According to Bombardier marketing, the aircraft breaks even
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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.
Indian regional jet
Indian regional jet
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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
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The aircraft claimed to offer
– 25% lower acquisition costs
– 25% lower operating costs
– 50% lower maintenance costs than existing turboprop regional aircraft.
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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
ATR-72
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ATR 72
ATR 72 was developed from the ATR 42
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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.
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Design
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– 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
PW127F turboprops, 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)
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Embraer jet
Embraer- ERJ family
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The aircraft ERJ 135-145 family is powered by two turbofan engines (Rolls-Royce
AE 3007)
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Thrust: 30 – 42 kN
Pressure ratio 20: 1
Turbine inlet temperature: 1300 K
Thrust to weight ration : 5: 1
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Capacity 37 – 122 passengers
Sold around 1800 jets in last 15 years
Service ceiling: 11278 m
Cruise speed:
828 kmph
Range:
3200 km
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The ERJ E-170-195 family employs GE CF34- 8E/10E engine series
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Thrust:
63 – 89 kN thrust
Range –
4000 km
Cruise speed: 890 kmph
80-122 passengers
Energy efficiency and load factor
EI 
EU
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EI = Energy intensity – energy consumed per ASK
EU = Energy usage- energy required per km
 = 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
(available seat per km)
EU of regional aircraft and their yearly average
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
EU comparison of large and regional aircrafts
Drastic decrease in the E indicates technological advancement due to demand for long distance travel
Specific fuel consumption of Engines
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
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)
Trends in structural efficiency
Aerodynamic efficiencies
Energy usage for various aircrafts
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
Operational sequence influence
Ground Efficiencies
Airborne efficiency
Energy usage Vs ground and airborne efficiencies
Operating costs
Pilot salaries and fuel costs
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1975
1999
1999
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Turboprop
Regional jet
Large jet
Pilot salaries (% of total cost)
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Turboprop
Regional jet
Large jet
Fuel costs (% of total cost)
Operational cost Vs Stage length
Regional Daily flights distribution in 2002
Comparison of fuel consumption
Turboprop
Propulsive efficiency
Turboprops and Turbofans
Why regional transport
• For regional
transport
– Many hubs located
around the many
centers
– Delhi, Mumbai,
Bangalore, Chennai,
Hyderabad
– Distance ~ 600 km
– Importance of
connectivity
Conclusions
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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
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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.
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%20t
omorrow.pdf