The PC pilot, Airplane design at your keyboard

By Peter Walpole, Canadian Owners and Pilots Association.

Designing and building a new airplane can be a long, arduous task. You start with an idea, grab a huge sheet of paper and a pencil, and begin. You choose a set of simple drawing tools: a compass, straight edge, eraser, French curve, and a calculator. After hours you usually have a garbage can full of scrap paper, and possibly a plan forward. But will your new plane fly? Now that's the question; and the heart of this program. In fact, AirplanePDQ is three very distinct components, wrapped into one. I apologize. I'm most definitely not a plane designer. I did do a little drafting many years ago. I can read a set of drawings. And I know how to make a computer work. So in reviewing this product I looked at it from a very personal point of view. I tried to make it all work for a total novice to plane design. Let's look at system requirements first. You'll need a PC with a Pentium chip working at 200 MHz or faster (that covers most every computer released over the last five or six years). You'll need about 120 MB of hard disk space and a very minimum 32 MB of RAM. As usual, any computer with more than these minima will perform much better. I worked with an optical mouse. If I were going to make a long-term attempt at aircraft design I'd invest in a digitizing tablet and stylus by the second day. I'd also soon be using a large screen monitor, though my 17" screen was OK.

INTELLICAD 2001
The first component of this package is a fully working edition of IntelliCAD 2001. This is an advanced technical drawing/drafting program. If you know AutoCAD, the top of the line design program, you'll know what I'm talking about. While AutoCAD is the "professional" drafting program on the PC, a number of very similar "clone" programs have been created over the years. IntelliCAD works "just like" AutoCAD. It produces compatible files. To most of us it's the same program working the same way. You can use the files produced by either design program on the other. IntelliCAD probably has a few limitations (if you are designing the next space shuttle), but they are not an issue here. Let's look at this design program first. This is most definitely not a simple program to learn. While the on-disk "Help" material is excellent, you may find it advisable to buy a manual on IntelliCAD or AutoCAD in order to learn not only the advanced aspects of the program, but also the basics. As far as I can tell, everything can be done at least three ways, even drawing your first simple line! You can choose to use various drop-down menus, or point and click buttons (many of which have drop down multiple choice options), or (and this is the way many professionals work) using an old-fashioned command line entry. Depending on your working style, you may find yourself designing by entering cryptic alpha-numeric code words and numbers, or clicking two or three points on your work sheet to create, curves, lines and polygons. That may sound difficult, but after a few hours of practice I was pointing and clicking and typing numbers to get my first simple drawings on the screen. As in an old fashioned drafting shop, you'll soon find the need for different colours and line types, to differentiate different parts and components of your drawing. That adds complexity at one level, but readability at another. It soon becomes second nature. Just as draftsmen use multiple layers of drawing paper to overlay objects on a drawing (think undercarriage, and wings, and fuel system on different sheets) IntelliCAD makes it very easy to draw these components on different layers. These can be viewed together or separated. They can also use different coloured lines. Once you get the hang of it, it's an easy concept to work with. After a few hours of practice you'll begin using the buttons or commands to zoom in on objects, cut and move them, alter lines, and generally build a reasonable drawing. Again, I'd suggest that novice draftsmen (male or female) learn to draw, and learn the program, before venturing too far into aircraft design.

YOUR FIRST AIRPLANE DESIGN 
Let's assume you finally have a basic idea of how to draw on a computer screen. Let's assume you can imagine a design in 3D in your mind. And let's assume you have a modicum of an idea of what sort of plane you would like to design. As you activate AirplanePDQ you are offered two choices: to make a drawing, or to design a plane. Take the second choice and you begin a design "wizard." In effect the second component of this program takes over and leads you through the start of the design process. You fill in a series of pre-design sheets on which you pick the type of plane you want and various target performance criteria. You can pick high or low wing, or biplane. Choose a target cruise speed, a stall speed, a weight, and even select from a number of standard engines. Bit by bit you can specify a wing span, choose the cross section of your wing, the dihedral and taper of all flying surfaces, and so on. If you know aeronautics that might mean something to you. As I said above, I'm a total novice. But I went ahead and by altering the specs of an included sample aircraft, soon had a totally uncontrollable aircraft part way through the design process. There are a couple of tentative aircraft designs given to you as samples. These can and probably should be used as starting points for your first attempts at airplane design. But how do you know if your target performance figures are reasonable or if your design might work? Here comes the third component of the program. As you build your design on the top of the "templates," as you modify the original design, you can quickly generate a series of reports. From your tentative design, the computer will do the math to create very detailed reports. Each document is opened in your web browser (and can be hard copied to your printer for permanent reference). I did a performance analysis of one of the samples. By then modifying things like the wing span, the engine type, and various configurations, I was able to come close to my target performance numbers. Of course these very much depend on the all-up weight of your project. As you build your design you can specify the type of construction (metal or composite). By picking various types of weight estimating methods, you can not only predict the CofG but also the flight envelope of your craft. Yes, these are subject to various design variables (too many body members, or too few), but the aeronautics section has a number of choices for you to make here too. Let's suppose the performance report tells you your wing is too heavily loaded. Since each major component is created on a separate layer of your drawing, you can experiment with resizing the wing. You might try various pre-scribed profiles (there are many built into the program), change the span and/or root dimensions, or try a sweepback or altered dihedral. It probably helps to know ahead of time how each should affect your plane's performance. Over a few hours I learned a lot just experimenting and generating various reports.

PROTOTYPE AND COMPUTERIZED FLIGHT 
In the real world, a new aircraft is computer flown well before the first piece of metal is cut, or composite laid down. With AirplanePDQ you too can try out your plane before you build the hardware. My colleague John Dale has written about his enjoyment of X-Plane, the computer flight simulation. AirplanePDQ includes a working edition of X-Plane. Now, in truth I never got myself to the point of generating a realistic plane design (as I said, I have no aspirations in that direction). But I did fly one or two of the included X-Plane aircraft available on my disk. The program is an amazingly detailed simulation with some stunning visual affects. It claims to very closely mimic the actual flying performance envelopes of the included designs. Once you have a reasonable design completed (or prototypable) you can export your design to X-Plane and fly it! Here's where you'll safely confirm that the CofG is most definitely too far back, the prop hits the ground as you lift the tail, and the stall speed is much too high. Of course, the various reports will have warned you, but sometimes experience is worth a thousand pages of cryptic reports and analysis, even if it's simulated experience.

PERSONAL ASSESSMENT 
I was overawed by the complexity of the program, for a few hours. But as I learned to use the many drawing tools built into IntelliCAD, I began to make my initial drawings match the ideas in my mind. Depending on your drafting skills, learning the base program may take a lot of practice and time. Expect to be frustrated with the steep learning curve. Once I had a handle on the drafting skills I ran into a wall. My total lack of knowledge of aeronautics meant I could not fairly assess the built-in aeronautical database. I assume that Dr. Gil Crouse Jr. (the program's creator), with his background in aircraft design and computers knows what he's doing. I'm assuming the majority of his thousands of worldwide customers are reasonably satisfied with the value they have received from this product. I have no hesitation in saying I learned a whole lot just by experimenting with various values in design sheets. As an aside: I would have appreciated a crash course in aeronautical design as I played with the program, but perhaps that's for another program. I found the program easy to set up. It was easy to use (within my set of limitations). It worked for me. I have no hesitation in suggesting that anyone venturing into aircraft design will find AircraftPDQ a useful tool at about $150 (Cdn). The ability to get a quick analysis of performance figures for a simple design might be worth this low cost. But the ability to actually (virtually) test fly the design might be a lifesaver.

CAUTION I've tried to simplify what is a very complex set of programs. They are undoubtedly very powerful. As with all power tools you need to know how to use them safely to avoid doing yourself harm. Learn the various components properly before you trust your life to them. But isn't that the whole idea of computerized simulation, you trust the equations to a computer chip before you work them for real. I think AirplanePDQ with its IntelliCAD component and X-Plane is remarkable good value, even if you never design or build an actual airplane. With this program you can dream and play, and learn.