Most all of us have ridden in airplanes, but it is hard to imagine how they were
designed.
This program demonstrates some of the tradeoffs involved in the design process, the
difficulty of the problem, and the way that computers can help. By choosing different
wings, tails, engines, and fuselage layouts, you can put together a complete airplane
design of your own and see if it will fly.
You become an airplane designer, faced with the many decisions that must be made, and aided by a computer analysis that provides quick feedback on the effect of each decision. Since you probably do not have the experience of a professional aerodynamicist, the program provides advice on what might be done to improve the design. The program's expert advisor uses a simple knowledge-based system, an example of how artificial intelligence may be used now and in the future to assist engineers.
Your problem is to design a 200 passenger commercial airliner that can fly from Washington D.C. to a destination of your choice. If your design is successful, you can then try to improve it. See if you can lower the ticket price that would have to be charged, or see how fast you can fly and still meet the design requirements.
The program can be run on Macintosh or Windows operating systems by clicking on the file adw.html or running Netscape Navigator and opening this file from the Open menu. It is best to expand the browser window so that the pictures are visible. It is sometimes nice to hide the buttons and other browser information so that more of the content is visible.
You may change many of the airplane's characteristics by selecting the icons in the menu bar. You can analyze the airplane at any time, but you may want to work your way through each of the design decisions from left to right when starting.
Clicking on the picture of the airplane in flight at the right of the menu icons causes the program to compute the performance of your design and draw a perspective view of it. Look at the specifications and suggestions in the data box, then try to improve the design by changing your selections.
Each of the pages of the program contain a link to a short help page on the topic
for that page. Click on the Help link at the bottom of the page for more information.
Additional technical support is available from Desktop Aeronautics. First check
our web pages at www.desktopaero.com for updates and FAQ's. If you don't find help
there, try e-mailing us at help@desktopaero.com.
While the program is simplified to make it fast and easy to understand, it utilizes the capabilities of modern PC's to perform "real calculations" in the manner that they would be done in an actual design study.
Several parameters are treated as constant in the analysis to improve turnaround and reduce complexity. While this limits the usefulness of the program as a research tool, it is desirable for the purposes here. The basic assumptions include:
Once again it must be stressed that this particular program, and indeed all programs of this sort, do not permit unlimited imagination. The design concept must be compatible with the assumptions of the analysis. In this case, this is more or less assured since the degrees of freedom are restricted. In current research work this concept is often not appreciated fully and strange or misleading results are common. A concerted effort has been made to avoid the possibility of such results here by not oversimplifying the analysis and by limiting the range of design options.
The major calculations required to compute the aircraft weight, drag, field length, climb, range, etc. were developed by Ilan Kroo and others. The method was originally developed to run in a batch mode on a VAX computer system but has most recently been translated into this Java-based set of applets. The methods are described in more detail in the paper, "Tail Sizing for Fuel-Efficient Transport Aircraft" by I. Kroo and published by the American Institute of Aeronautics and Astronautics in 1985. The basic methods have been used in several research programs at NASA's Ames Research Center and in aircraft design courses at Stanford University.
Although the user interface is easy to use and the design options are limited to streamline the process, the basis of the analysis methods have not been simplified to the point of uselessness. The program includes such effects as: the change in drag associated with lower Reynolds numbers at higher altitude; a transonic drag increase based on flight test data of several transport aircraft sensitive to sweep, thickness, lift coefficient, and airfoil type; empirical data based on a rational correlation parameter for weights of the components. Aircraft balance is computed and the wing is positioned on the fuselage to assure an assumed stability level.
The original version of this program was developed for Apple Computer and the Smithsonian Air and Space Museum. The present version has been completely rewritten for use on the internet, intranet, or local computer. The user interactions and graphics are handled by Java programs that communicate with each other using the http cookie specification. The current design is always saved and the user may restart the browser at a later time to complete the design. A future version will permit the user to save several designs and compare them with others on the internet.