## Solutions

### Real-Time Wind Data

This example uses the NOAAWindData function to obtain real-time winds aloft data from the NOAA website. The data is available for several geographic regions in the United States, at altitudes from 3,000 to 53,000 ft. The plot to the right shows a vector wind field for a large region of the midwest. Real-time winds aloft data can be used to plan flight trajectories, especially for launch vehicles and airships, whose performance can be greatly impacted by wind.

### Eigenstructure Design of an Aircraft Controller

This example is drawn from Stevens and Lewis, "Aircraft Control and Simulation." A CCV aircraft is controlled using full-state feedback with a controller designed through eigenstructure analysis. Eigenstructure analysis allows the designer to select both the closed loop eigenvalues and part of the closed loop eigenstructure. This technique has been applied to many designs, including an A-10 flight/fire control system. The eigenvectors are shown above as an example of one of the many graphical design tools available as part of the toolbox.

### Gas Turbine Engine Analysis

The gas turbine performance and analysis tools include ramjets, turbojets, dual spool turbojets, turbofans, turboprops and mixed flow turbofans. Afterburners are built in to the turbojet and turbofan modes. The example shown on the right gives the specific thrust of a turbofan engine over a range of Mach numbers. You can study an engine's performance by varying any two parameters at a time. Engine models can be ideal or include component efficiencies. Study of off-nominal performance can be done with the performance analysis functions.

### Aircraft Performance Analysis

The Breguet range equation is one of the performance analysis tools. The demo to the right was run by just typing BrequetRangeEquation at the MATLAB® command prompt. It shows that the maximum range of the Concorde can be achieved when it flies near Mach 1.35.

### Optimal Helicopter Control

The example to the right is taken from Bryson, "Control of Spacecraft and Aircraft." An optimal controller is applied to the problem of helicopter hover. The simulation is run through the toolbox GUIs, which show an animation of the helicopter motion. The simulation may also be run in batch mode for increased speed. Notice that the HUD includes cyclic and collective pitch controls! The controller uses cyclic, collective, throttle and tail rotor collective to maintain a stable hover. The model used is a linearized model of the helicopter model. Nonlinear models are available in the companion package, MultiVehicleSim.