Nuts and Volts - April 2014

The good news is we can also exploit this quirk of our own visual dominance to both simplify our simulator design and to radically increase the sensations in our ride. For example, most commercial simulator’s range of motion is limited to only six degrees of motion. Yet, the riders inside feel as if they are moving as much as 360 degrees!

The reason for this is that the motion base only needs to provide a few moments of acceleration in any given direction. Then, the video the rider is watching takes over to make them feel as if the motion is continuing.

The effect is very striking, and I have had riders who were absolutely certain they had done a full loop in a simulator which actually only moved a few degrees.

Next, ideally, your simulator’s cabin should be designed to move in conjunction with what is happening in your screen imagery. Motion should not be tied simply to joystick control as many simpler video games have done in the past. Locking motion to screen movements mimics how things feel in a real airplane, for example. Changes in thrust, rudder, and ailerons bring about unique attitudes in the airplane that are not dictated by stick position only.

Consider making a 360 degree turn in your car at 5 MPH mph or at 25 MPH. Though the wheel may be held in the same position, the forces you would feel would be entirely different at those two speeds. This is why simulator designers think in terms of accelerations and not movement or platform angles.

Another important reason to make certain that screen and platform motions are in sync is that most pilots will become nauseated within minutes when screen and platform are out of sync. It’s possible in a closed-loop system to throw the screen and platform out of sync intentionally, however.

This always struck me as a possibly useful way to induce spatial disorientation and/or test anti-nausea protocols.

It’s also a great way to make friends sick. Deciding on an Actuator

There are three basic ways that most simulators are moved. These are with cylinders (hydraulic or pneumatic), servo/electronic, or manual weight shift operation. All of these have pros and cons.

For the purpose of this article, I’ll stick with a pneumatic system as this is robust, relatively inexpensive, and something I’ve loved designing with for years. Since the electronics to be described represent a full closed-loop system, they should lend themselves to any actuator you choose to employ. So, feel free to use your favorite.

One advantage of pneumatics in flight simulation is that you are essentially riding on air shock absorbers. This means your flights will be glass smooth with no mechanical sounds or vibrations.

Each axis on which your simulator can move is referred to as

40 April 2014

A Quick Warning

Before we go into the nuts and bolts of this build, I wanted to offer a quick and gentle warning.

Even though a simulator is a ground-based machine, the forces at work are still quite significant. Pistons, electric actuators, and even hydraulics often exert thousands of pounds in force on single points.

In early tests of the larger simulator, a broken weld nearly caused an eight foot plunge into metal scaffolding on a test “flight” I made.

After scrambling free, I had to laugh since I assumed I could tell the story of being the only guy who nearly was killed in a simulator crash! However, whenever I’ve told this story to simulator enthusiasts, they’ve been quick to offer their stories along the same lines. It almost seems the rule rather than the exception.