This section introduces a NASA HL-20 lifting body airframe model that uses blocks from the Aerospace Blockset™ software to simulate the airframe of a NASA HL-20 lifting body, in conjunction with other Simulink® blocks.
The model simulates the NASA HL-20 lifting body airframe approach and landing flight phases using an automatic-landing controller.
For more information on this model, see NASA HL-20 Lifting Body Airframe.
The NASA HL-20 lifting body airframe example illustrates the following features of the blockset:
Representing bodies and their degrees of freedom with the Equations of Motion library blocks
Using the Aerospace Blockset blocks with other Simulink blocks
Feeding Simulink signals to and from Aerospace Blockset blocks with Actuator and Sensor blocks
Encapsulating groups of blocks into subsystems
Visualizing an aircraft with Simulink 3D Animation™ and Aerospace Blockset Flight Instrument library blocks.
To open the NASA HL-20 airframe example, type the example name,
at the MATLAB® command line. The model opens.
The visualization subsystem, multiple scopes, and a Simulink 3D Animation viewer for the airframe might also appear.
The model implements the airframe using the following subsystems:
The 6DOF (Euler Angles) subsystem implements the 6DOF (Euler Angles) block along with other Simulink blocks.
The Environment Models subsystem implements the WGS84 Gravity Model and COESA Atmosphere Model blocks. It also contains a Wind Models subsystem that implements a number of wind blocks.
The Alpha, Beta, Mach subsystem implements the Incidence, Sideslip, & Airspeed, Mach Number, and Dynamic Pressure blocks. These blocks calculate aerodynamic coefficient values and lookup functionality.
The Forces and Moments subsystem implements the Aerodynamic Forces and Moments block. This subsystem calculates body forces and body moments.
The Aerodynamic Coefficients subsystem implements several subsystems to calculate six aerodynamic coefficients.
Running an example lets you observe the model simulation in real time. After you run the example, you can examine the resulting data in plots, graphs, and other visualization tools. To run this model, follow these steps:
If it is not already open, open the
In the Simulink Editor, from the Simulation tab, select Run.
The simulation proceeds until the aircraft lands:
View of the landed airframe
Plot that Measures Guidance Performance
Plot that Measures Altitude Accelerations Mach
Plot that Measures Inertial Position
Plot that Measures Demand Data Against Achieved Data
By default, the airframe animation viewpoint is
position, which means the view tracks with the airframe
flight path from the rear. You can change the animation point of view
by selecting another viewpoint from the Simulink
3D Animation viewer:
and click the Simulink
3D Animation viewer.
From the list of existing viewpoints,
change the viewpoint to
The airframe view changes to a fixed position.
Start the model again. Notice the different airframe viewpoint when the airframe lands.
You can experiment with different viewpoints to watch the animation from different perspectives.