Aerospace Blockset 3.6

NASA HL-20 Spacecraft Automatic Landing Demo

This demonstration shows NASA's HL-20 lifting body modeled with Simulink®, Aerospace Blockset™, and Stateflow®. The vehicle model includes the aerodynamics, control logic, fault management systems (FDIR), and engine controls (FADEC). It also includes environmental effects such as wind profiles for the landing phase. The entire model simulates approach and landing flight phases using an auto-landing controller. We use an interface to FlightGear, a open-source flight simulator package, to visualize this model.

Contents

NASA HL-20 Background

The HL-20, also known as personnel launch system (PLS), is a lifting body re-entry vehicle that was meant to complement the Space Shuttle orbiter. Designed to carry up to ten people and very little cargo[1], the HL-20 lifting body was to be placed in orbit either by launching vertically using booster rockets or by being transported in the payload bay of the Space Shuttle orbiter. The HL-20 lifting body was intended to have a powered deorbiting accomplished with an onboard propulsion system. Its reentry was to be nose-first, horizontal and unpowered. The HL-20 lifting body was developed as a low-cost solution for getting to and from low-Earth orbit. The proposed benefits of the HL-20 included reduced operating costs (due to rapid turnaround between landing and launch), improved flight safety, and the ability to land conventionally on runways. Potential scenarios for the HL-20 were the orbital rescue of stranded astronauts, crew exchanges for the International Space Station if the Space Shuttle orbiter is not available, observation missions, and satellite servicing missions.

Overview of the Model and Model Components

The capabilities of Simulink® technical computing software help with modeling such a complex system as the HL-20. In addition to highlighting different parts of the model, the following video below shows how this model uses Simulink capabilities.

You can use the Web view of the model provided below to explore the model structure. To view and navigate the Web view you need Microsoft Internet Explorer with Adobe SVG plug-in or Mozilla Firefox 1.5 or later. To download Adobe SVG plug-in for Internet Explorer, follow this link:

Adobe SVG plug-in for Internet Explorer.

Follow this link to view the HL-20 Simulink model:

Web view of HL-20 Simulink model.

Using Aerospace Blockset™ for the HL-20 Model

Aerospace Blockset can be used to rapidly develop a model of a vehicle's dynamics and environment, as well as for flight visualization. In the HL-20 model, we use Aerospace Blockset to model six-degrees-of-freedom vehicle dynamics; the effects of wind gusts, atmosphere and Earth's gravity; calculate flight parameters; do coordinate transformations and unit conversions; and to visualize the flight in a three-dimensional environement.

Watch the video showing the use of Aerospace Blockset™ in the HL-20 model.

Additional Information About NASA HL-20

For additional information on the NASA HL-20, see the following article from the July 2002 issue of MATLAB® Digest :

NASA HL-20 Lifting Body Airframe Modeled with Simulink and the Aerospace Blockset

[1] Jackson E. B., Cruz C. L., "Preliminary Subsonic Aerodynamic Model for Simulation Studies of the HL-20 Lifting Body," NASA TM4302 (August 1992)