L/D Vario is an app for gliding airsports such as wingsuit flying, tracking, canopy piloting, paragliding, etc. It is a complete flight instrument, measuring the most important aerodynamic parameters of the gliding flight: lift-to-drag ratio (L/D), air glide ratio (GR), current horizontal and vertical airspeeds, and sustained horizontal and vertical speeds normalized to sea level (a.k.a. the polar curve). It uses the accelerometer and barometer (or GPS) in your device and solves Wingsuit Equations in real time to measure flight parameters and provide instant visual and audio feedback.
Unlike GPS that measures ground glide ratio (which is distorted by wind and dynamic maneuvers such as dives and plane outs), L/D Vario measures true, instant L/D — your aerodynamic finesse — independent of wind and dynamic distortions, so you can maximize your L/D much faster and more reliably. Also, it calculates the glide ratio relative to the air, not to the ground, since it uses the altitude from the barometer (or GPS) which is not distorted by the wind, unlike the GPS position/groundspeed. Advanced multiple-layer algorithms are used to calculate smooth descent rate and vertical acceleration from noisy altitude data. All these flight parameters - L/D, GR, sustained and current airspeeds - help you understand various flight modes and learn quickly how to fly better.
To use the app in flight, your device needs to be mounted on a vane that is positioned in undisturbed air stream (away from the body and wing at least 2-3 feet) and is precisely aligned with the relative wind at all times, so that its Y-axis (from screen bottom to top) is parallel to the relative wind, and X-axis (left-right) is parallel to the ground. You can then use your Bluetooth headphones to listen to the feedback tone and voice.
Use of devices with high-speed barometric sensors (60Hz or faster) is highly recommended for the feedback lag not to exceed 0.2s. Some known devices with high-speed barometers include: phones - Google Nexus 4 and Sony Z3 Duos (30Hz), smartwatches - LG G Watch R (90Hz), Huawei Watch (20Hz), Nixon the Mission (165Hz).