Good Vibrations

The sense of vibration sits somewhere between touch and sound. Its unique experience depends much on the frequency: low frequencies are felt, while higher frequencies are heard. In an optimal simulation experience you need, of course, both. Today’s technology helps across the range of vibrations and good simulation platforms should be able to offer that additional layer of realism to the simulator pilot. In this brief article will describe three systems that, interconnected and fed by the flight simulation software, in this case X-Plane 11r2’s stock BE-58, give you exactly that: good vibrations.

The first system addresses the low range of vibration, the rumble you feel when you start the engine/s, or touchdown on the runway when the wheels begin to spin or many other mechanical configuration changes in flight and on the ground. In this example we used a single BFF Simulation bass shaker driver card and software (BFF’s and XPUIPC) and two AURA shakers mounted right under the pilot ad copilot seats. We used a Meanwelll power supply, providing 150W at 24V and Monster speaker cables. BFF’s hardware is fed by a digital input via a provided USB to TTL cable. That allows the processor within the driver to sense and output a number of nuanced changes in vibration amplitude and frequency within the airframe, using the reference provided by XPUIPC running as a plugin within X-Plane. The BFF Shaker card is controlled by software which provides fine adjustments across a number of parameters and testing tools.

The second system outputs the sound in the audible range, which in most simulators includes the actual sound of engines, wind, atmospheric conditions like rain, control surface and gear activation and more. For this we used a 125 Watts Kicker DXA 125.2 automotive amplifier that has a good range especially in the bass and medium frequencies, critical for wind and control surfaces noise, and plenty power. We used two bookshelf JBL speakers mounted inside the cockpit. In the X-Plane sound settings we prioritized cabin and environmental sounds and turn down most anything else.

The third system is voice communication to ATC service. Since we like to use a standard aviation headset, we interfaced our D. Clark headset using a small battery-operated circuit to resolve the output impedance mismatch. We plugged the whole thing into a Sabrent USB audio converter.

In total we used the following connections: One line out for the speakers and two USB ports, one for the headset and one for the shaker hardware digital input.

The price including the amplifier, speakers, shakers and BFF hardware as described above is in the $700 range. Considering the usual variables of shipping, taxes, and components you may already have you may actually spend a different amount.

We assembled the equipment and secured it to the frame of our test XPlane-11 based simulator, which in this case has a perforated angle steel chassis, which we find ideal to prototyping and experimentation. Power supply was connected to a strip for quick on and off of all ancillary equipment.

The results couldn’t be more pleasant. Turning the key/s to start the engines makes immediately the cost, and time spent, very reasonable. Probably, however, the best experience with vibration realism was in an engine loss event. When flying a real light twin engine aircraft in training, say a Baron or a Seneca, there is an expected control inputs change when losing an engine (dead foot, dead engine) but, for many pilots, the change in vibration is also an overall telltale sign that something is amiss. Changes in vibration, and relative expectation of them, also occur when lowering the gear, deploying flaps and speed brakes, even ice accumulation, giving you hints of how things are functioning. These changes are now all sensed and transmitted to the shakers by the BFF hardware and, to some extent, by the sound system, making your simulated flying experience even closer to reality.

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