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
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
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
This always struck me as a possibly useful way to
induce spatial disorientation and/or test anti-nausea
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.
So, be careful in your design and testing, and treat this
like a real vehicle, which it is — even if most of the motion is
in our minds!
; FIGURE 1.