Take-off Cycle Research Articles

Analysis of Departure and Arrival Profiles Using Real-Time Aircraft Data

The quantity and rate of fuel burned during aircraft operations forms the basis of all emission inventories at airports. The international standard for calculating fuel burn and emissions produced is the landing and takeoff cycle of the International Civil Aviation Organization and forms the basis for many emission inventory models and emission charging schemes at airports. The acquisition of real-time aircraft flight data recorder information provided a unique opportunity to compare actual operational fuel flows and times in mode to the International Civil Aviation Organization standard. For departures, there is tremendous variety in fuel flow patterns, rates of fuel flow, and times in mode. Only 67% of the flights analyzed show a classic transition from takeoff to climbout. Most of the remaining flights showed essentially flat-line fuel flow profiles. All aircraft showed some fuel flow rates indicative of reduced-thrust departures. The certificated values for departure fuel burn matched favorably to the real-time totals for four-engine aircraft. However, for the twin-engine aircraft in this study, total departure fuel burn was grossly overpredicted, due to shorter observed departure times in mode. The average approach times in mode were slightly higher than the International Civil Aviation Organization norm, but approach fuel flow rates were significantly lower, yielding lower total fuel burn values. In general, total fuel burn for both departures and arrivals is overestimated by the International Civil Aviation Organization method.

Particle and Gaseous Emissions from Commercial Aircraft at Each Stage of the Landing and Takeoff Cycle

A novel technique was used to measure emission factors for commonly used commercial aircraft including a range of Boeing and Airbus airframes under real world conditions. Engine exhaust emission factors for particles in terms of particle number and mass (PM2.5), along with those for CO2 and NOx, were measured for over 280 individual aircraft during the various modes of landing/takeoff (LTO) cycle. Results from this study show that particle number, and NOx emission factors are dependent on aircraft engine thrust level. Minimum and maximum emissions factors for particle number, PM2.5, and NOx emissions were found to be in the range of 4.16 x 10(15)-5.42 x 10(16) kg(-1), 0.03-0.72 g.kg(-1), and 3.25-37.94 g.kg(-1), respectively, for all measured airframes and LTO cycle modes. Number size distributions of emitted particles for the naturally diluted aircraft plumes in each mode of LTO cycle showed that particles were predominantly in the range of 4-100 nm in diameter in all cases. In general, size distributions exhibit similar modality during all phases of the LTO cycle. A very distinct nucleation mode was observed in all particle size distributions, except for taxiing and landing of A320 aircraft. Accumulation modes were also observed in all particle size distributions. Analysis of aircraft engine emissions during LTO cycle showed that aircraft thrust level is considerably higher during taxiing than idling suggesting that International Civil Aviation Organization (ICAO) standards need to be modified as the thrust levels for taxi and idle are considered to be the same (7% of total thrust) (Environmental Protection, Annex 16, Vol. II, Aircraft Engine Emissions, 2nd ed.; ICAO--International Civil Aviation Organization: Montreal, 1993).

An evaluation of possible EU air transport emissions trading scheme allocation methods

The European Commission has been requested by member states to study the incorporation of air transport into their existing emissions trading scheme (ETS). Only CO 2 is to be included, at least initially. This paper focuses on the method of allocation of emissions permits in the EU context. It has been assumed here that the EU ETS will be applied only to intra-EU flights and that airlines will be the entities selected for implementation. Three UK airlines were selected to evaluate three main types of allocation: grandfathering, auctioning and benchmarking. The airlines were representative of the three major airline business models: network, low-cost carrier and charter/leisure. Based on 2003/2004 aircraft/engine type and operating data, the per passenger impact of each allocation option was analysed for each airline. A new benchmarking approach is proposed that takes into account both the landing and take-off (LTO) cycle and per kilometre emissions: this avoids penalising shorter sector operators and focuses on the damage caused by aircraft and their engines and not on passengers.

Gas turbine disk-blade attachment crack

Evaluation of a gas turbine disk revealed a crack in the blade attachment area. The subsequent effort to understand the origin of this crack led to a series of analyses that included computing the stresses on the attachment, characterization of fatigue crack growth, and a model for fretting fatigue crack growth. These elements were brought together to simulate the conditions that led to the cracking. It is concluded that the crack was probably caused by fretting fatigue induced by the stresses related to normal takeoff and landing cycles and exacerbated by aircraft maneuvers, and that short periods of blade resonance may have contributed to the cracking. If material had not been removed from the attachment surface of the disk by service-induced wear, it is likely more cracks would have been found.

Validation of Approach and Climb-Out Times-in-Mode for Aircraft Emissions Computation

The first aircraft emissions standards were proposed by the U.S. Environmental Protection Agency (EPA) in “Proposed Standards for Control of Air Pollution,” in 1972. Landing–takeoff cycles (LTOs), aircraft engine emissions factors, and times-in-mode (TIMs) were the basis of computing aircraft emissions. Discrete values were assigned to each TIM. No formal record of the derivation of these TIMs is available. Thirty years later, the same TIMs presented by EPA in 1972 are still used in developing aircraft emissions inventories. Today’s aircraft perform much differently than did aircraft from the past. A study was attempted to validate the TIM values currently used with radar data. A sample emissions inventory will be developed for Chicago O’Hare International Airport to show the impact of the proposed changes of TIMs.

STAGED COMBUSTION CONTROL FOR AVIATION ENGINES: A MULTI-OBJECTIVE OPTIMISATION APPROACH

This paper focuses on multi-objective optimisation of staged combustion control for aviation gas turbine engines. Pareto optimisation based multi-objective genetic algorithms are used to design the fuel distribution control laws of a staged combustor. The results of control system parameter optimisation over International Civil Aviation Organisation Landing and Take-off cycle and the typical engine operation condition are presented. An analysis of the control-related issues for optimal fuel distribution is presented.