14 Aircraft performance
Author: Junzi
Author’s note: This part goes through all the most commonly used data formats in the aviation and ATM data analysis community.
Here are some references for BADA nuic2010?, OpenAP [1], [1],
Aircraft performance models are used to study how aircraft fly. They are based on the laws of physics and can be used to predict the aircraft’s speed, altitude, thrust, drag, and fuel consumption. There are different categories of performance models, with varying levels of detail. The most detailed, non-linear six-degree-of-freedom models are commonly used in aircraft control studies. Air traffic management research often assumes a stable aircraft and neglects fast rotational dynamics. This assumption means that a point-mass aircraft performance model is sufficient in most use cases. Such a point-mass model is used throughout this entire dissertation.
There are two different types of point-mass models: kinematic and dynamic. The primary difference is that while a dynamic model focuses on forces and energy, a kinematic model deals only with aircraft motions.
A well-know aircraft performance model, BADA nuic2010?, is developed by Eurocontrol. It inlcuded both kinematic and dynamic models. The BADA aircraft performance operation file (OPF) models the dynamic properties of the aircraft, while the airline procedures file (APF) models the kinematic aspects of flights.
Unlike BADA model that relies on strict user license agreement, OpenAP [1], [1], a recent open aircraft model also provide both kinematic and dynamic models for common aircraft types.
14.1 Kinematic model
The kinematic model is a simplified way of describing aircraft motion without considering the forces involved. It is commonly used to analyze the motion of an aircraft during various flight phases, including takeoff, initial climb, climb, cruise, descent, final approach, and landing. For example, the General Aircraft Modelling Environment (GAME) calders2002?, a very early model also developed by Eurocontrol, is another example of a kinematic performance model.
The kinematics of aircraft motion varies across different flight phases. Fortunately, we can directly observe essential parameters such as velocity, altitude, acceleration, and range using aircraft surveillance data. By leveraging openly accessible ADS-B data, we can construct accurate models, as demonstrated in the OpenAP kinematic model sun2019wrap?.
This approach enables us to gain valuable insights into the behavior and performance of aircraft during each flight phase. Therefore, the use of ADS-B data in constructing kinematic models is a powerful tool for analyzing and improving flight operations.
OpenAP kinematics table here
BADA APF
14.2 Dynamic model
When aircraft forces are taken into account, a more complex model is required to accurately describe the aircraft’s performance compared to what a kinematic model can provide.
n air traffic management-related studies, the total energy model is commonly used to describe the aircraft’s behavior. This model takes into account the conservation of total energy generated by the aircraft’s engines to counteract drag and the change of kinetic and potential energy. This model is especially useful for trajectory based studies, like optimization and fuel estimations.
The main components of the dynamic model are thrust, drag, and mass of the aircraft. Thrust represents the force generated by the aircraft’s engines, while drag represents the force that opposes the motion of the aircraft through the air. Mass refers to the total weight of the aircraft, including fuel and passengers.
total energy equation + force figure
BADA OPF
OpenAP YAML
14.2.1 Thrust
Thrust is produced by the engines of the aircraft, and modeling aircraft engine performance is a complicated research area. In air traffic management studies, the thrust model is simplified. Instead of trying to model the performance of engines, we are interested in the net force that is produced by the aircraft in different stages of the flight. For example, in BADA v3, thrust is modeled as a polynomial model related to the aircraft altitude.
Aircraft thrust is a parameter that cannot be derived using surveillance data. We have to rely on open models that are created by other researchers. In OpenAP, an empirical model for two-shaft turbofan engine thrust calculation proposed by bartel2008?. The model is constructed and evaluated based on real engine performance data. Thus, in this dissertation, thrust is modeled as functions of both altitude and speed, as well as the vertical rate. This offers a more accurate interpolation than the BADA v3 model, in which the thrust is only dependent on aircraft altitude.
14.2.2 Drag
drag polar models, how to estimate them, sample figures from OpenAP
14.2.3 Mass
aircraft mass, why it is hard to find, and how to estimate them
14.3 Other models
ECAC Doc 29 [4]
Piano-X