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ClearNav Vario



Vario Overview

The ClearNav Instruments vario system has been designed to provide glider pilots with the best possible climb and speed-to-fly guidance, as well as valuable secondary information, including wind speed and direction, air and ground speeds, and altitudes.

The vario can use either probe or purely electronic Total Energy compensation. It fits into a single 57 MM hole and the “black box” (Air Data Computer or “ADC”) can mount either directly to the display module or separately for maximum flexibility.

The vario has been designed to be fully compatible with the “ClearNav” display and, through the use of a serial data port, can also integrate with other moving map/glideslope devices. Go to CNv Vario Features for details.

We are now hard at work on completing and testing many new features.


The ClearNav Vario is available in two models: “Club” and “Cross Country”.

Both models offer state-of-the-art total energy variometry for climb and cruise. High performance pressure transducers and advanced digital filtering yield rapid, but well damped response.

Feedback from our customers confirms that the vario has an uncanny ability to respond to lift without the frequent false alarms which plague other fast varios.

A highly visible mechanical pointer responds rapidly and smoothly to glider vertical motions, and a high resolution digital display shows both a short-period average rate of climb, and the average since the climb began.

Audio tones allow for centering without reference to the display.

Both models provide netto and speed to fly information and both are extensively user-configurable to accommodate any sailplane and any pilot preference.

Speed-to-Fly information is presented by visual display, audio tones or both.

Other features common to both models are a unique “Get Home” screen which provides navigation and glideslope information to the home field, winds (headwind/tailwind and vector wind) and electronic Total Energy options.

A simple user interface and a profile editor make the products both easy to use and easy to configure.

The Cross Country model adds: a secure flight recorder, navigation to a point in a waypoint database, serial communications to both the ClearNav Fligh Computer and other third part devices.


The System
Feature Club Vario Cross Country Vario
Air Data Computer
Display and Controller
Profile Editor
Simple User Interface
“ClearNav” Integration  
Feature Club Vario Cross Country Vario
Total Energy
Get Home Navigation
Electronic Total Energy
Secure FR  
Task Management  
CAI Dataport  


In-Flight Information and Settings Screens
Feature Club Vario Cross Country Vario
Netto and Relative Netto
Outside Air Temperature  
MacCready Value
Other Settings
Feature Club Vario Cross Country Vario
Time Constants
Dry Weight Adjust
Local Time
Tools and Information
Feature Club Vario Cross Country Vario
Flight Logs  
Pointer Zero
Software Updates
Other Features
Feature Club Vario Cross Country Vario
Cruise/Climb Switching


Air Data Computer Up

The ADC is housed in a small aluminum enclosure which may be attached to the display/controller or separately mounted as required. In addition to four pressure transducers (Pitot, Static, Total Energy, and the cockpit static-referenced sensor mandated by the IGC for Secure Flight Recorders) the ADC has a three-axis accelerometer, a three-axis rate sensor (gyro), and a three axis magnetometer. The ADC provides connectivity via two CAN bus jacks, a serial jack and a USB jack. The USB jack can supply 950 mA to a connected device. A ten-position connector provides power and ground, and inputs for gear and spoiler alarms, a temperature probe and cruise/climb switching.


Length 4.25" 108mm
Width .787" 20mm
Height 2.44" 62mm

Display and Controller Up

The display/controller mounts in a 57 MM hole. A highly visible mechanical pointer driven with a micro-stepper motor displays Total Energy, Netto, or Relative Netto values. The high contrast, high resolution monochrome LCD can display a large range of in-flight data and is used in conjunction with two rotary encoders to control the instrument.

A telephone cable, terminated with modular plugs brings power and data from the ADC and carries data to the ADC. (A longer then stock cable can be used to position the ADC further away from the display/controller if required. The ADC UP/AFT orientation must be maintained in all installations.)


Profile Editor Up

Many settings can be managed with the display/controller alone, others, such as polar selection, pilot name, audio behavior and the configuration of inputs on the ten-position connector, are managed with a PC-based editor. Multiple profiles may also be used to experiment with different instrument settings without having to make numerous changes in flight.


Simple User Interface Up

We have chosen a particularly simple UI which is easy to learn and hard to forget. There are two rotary knobs, one (at the top left) selects which screen is displayed (Cruise/Climb, MacCready, wind, etc). The other (at the bottom right) changes the value of a number on the selected screen (such as MC, altimeter setting, ballast, pointer time constants etc). For screens presenting multiple choices (such as flight logs, profiles etc) the knob highlights the active choice. Display screens are grouped to simplify their use: Flying Screens are used for items most commonly needed in flight, Settings Screens are typically used on the ground and are seldom used in flight, and Tools and Information screens are reserved for items which are not frequently used.


Almost all set values are “sticky” – once set they remain as set until set again. Generally the stickiness is indefinite. Some parameters, such as MC, bugs and ballast, are reset to default values when the vario is turned on the next day.

In general there is no “set/acknowledge” function – after a parameter is changed it remains at its new value on paging away to another screen.

ClearNav Integration Up

If the vario is connected to a ClearNav display, MC, bugs, and ballast values are synchronized and tasks created using the ClearNav display may be copied to the vario. Copying a task to the vario gives the pilot a completely independent navigation and task management option as a backup.

Total Energy Up

Audio and pointer give fast Total Energy feedback to the pilot and the climb screen has two averagers for longer term assessment of climb:


This and all screen images are simulations.

The “smart” 20 second digital averager (top right) is a filtered average climb rate. On the transition from cruise to climb this averager is reset. It initially shows the one second average, then the two second average etc until at twenty seconds and longer it shows the twenty second moving average.

A second averager (bottom right) shows the average climb for the current thermal from the start of the climb to now. This value is just the change in total energy divided by elapsed time since the start of the climb. Both averagers have associated timers (top left and bottom left).

Speed-to-Fly (STF) Up

Speed to Fly is displayed both in traditional push/pull format (left) and numerically as a smoothed Speed to Fly number (lower right). Audio tones allow accurate speed control without reference to the display.

The profile editor provides full control over the audio, including deadband width and optional suppression of sink tones. The time constant controlling the numeric Speed to Fly value is also controlled via the profile editor.


Wind Up

The winds screen shows headwind/tailwind component (left) and vector wind (lower right). The arrow (top center) shows the direction of the wind relative to the nose of the aircraft.


Get Home Navigation Up

This screen gives all the information needed to get home including distance, bearing and track, and an arrow which points to the home field, When the arrow is aligned with the nose of the glider it is flying direct to home. The arrival height is on the bottom of the screen. If this value is zero the glider will land just as it gets home (assuming sink and lift balance!).


Electronic Total Energy Up

“Electronic” Total Energy does not make use of a Total Energy probe but uses the pitot and static pressures instead. This allows the vario to be used in gliders not equipped with a Total Energy probe. The electronic Total Energy system may also be used in conjunction with a Total Energy probe to make adjustments to the probe response. This can be very useful for Total Energy probes with under-compensation behavior.

Secure Flight Recorder Up

Approved for all flights including World records.

Task Management Up

Two levels of task management exist. The simplest allows a third party device to export a declaration (including the task and its control points) to the Secure Flight Recorder. Normally the task would be managed automatically so that after the start the active waypoint becomes the first task control point etc. We also provide a task screen which gives the pilot the ability to select the active waypoint using the lower right encoder.


It is also possible to export waypoint databases to the vario using the Profile Editor and a USB drive. If a waypoint database is present then there are additional options, including the ability to select landpoints ranked by distance:


Or alphabetically:


Using the all-control-points option it is possible to manage any task quite independently. This provides a valuable backup in the event of a primary nav failure.

CAI Dataport Up

Many third-party applications can send and receive data over this open-source utility.


Netto and Relative Netto Up

The netto value at the top right of the cruise screen is the average (with a time constant which can be set by the pilot) of the airmass vertical motion. This field can alternatively display relative netto (the climb rate that could be achieved if the glider were slowed to thermalling speed and put into a 45 degree bank).


Speeds Up

A dedicated screen shows Indicated, True, and GPS ground speeds.



There are two altitude screens. One is conventional and shows msl altitude and the barometric pressure (“altimeter setting”), along with the GPS (WGS-84 ellipsoid) altitude:

The second altitude screen shows logger altitude, pressure altitude, and msl altitude using the barometer setting of the first screen.
Logger altitude is the one that determines penalties so it’s very useful to know. Because the static reference for the logger is the cockpit, not the system static, the logger altitude is often different from the system altitude.
Pressure altitude is useful if airspace is defined using flight levels.
The third line is the system msl altitude


Outside Air Temperature Up

An optional OAT sensor can be provided. It is wired to the ten-position connector. OAT corrections to TAS are minor but are done automatically when an OAT is present. Since a knowledge of the outside air temperature is often useful there is a screen to display this value.

Voltmeter Up

The vario supply voltage is displayed on the same screen as the OAT.

MacCready Value Up

Both the climb and the cruise screens show MC values but a separate screen is used to set the MC value. This is the first screen which appears when the top right encoder is rotated clockwise. The Speed to Fly number is the neutral air value – it is the cruise speed in air with no vertical motion, taking into account the polar and the MC, ballast, and bugs settings.


Volume Up

By default the lower right encoder is the volume control.

Ballast Up

The amount of ballast can be set on the top line:

The second and third lines show the total weight (dry weight plus ballast) and the wing loading.


Bugs Up

The bugs screen allows for an estimated performance degradation. “100%” means 100% performance (not 100% bugs!). The computed best L/D value is a reminder of the performance degradation.


Time Constants Up

The time constants for the pointer and audio can be adjusted in flight. The digital averager time constant for netto may also be adjusted in flight.

Dry Weight Adjust Up

This facility is useful for two-seat gliders and for any glider where there might be large variations in pilot weight. The “base” weight (844 lbs in the example below) is set with the profile editor and can be adjusted with the LR knob.


Local Time Up

Both UTC and local time are displayed. Both are derived from the GPS engine.

Polar Up

Polars for known gliders are provided in the CAI format in the Profile Editor. For two-span gliders we provide a facility which allows for switching between polars:

15M 18m

Backlight Up

Under some conditions the display visibility can be enhanced through the use of the backlight.

Units Up

All combinations of the following basic units of measure are supported:

Length: sm, nm, km, m, ft
Area: m2,ft2
Volume: US gal, l
Mass: lb, kg
Speed: mph, kt, km/h, m/s
Temperature: ºF, ºC


GPS data is available and includes position, time, altitude, EPE etc.

Flight Logs Up

Flight logs with logging intervals of 1, 2, 4, 8, or 12 seconds can be downloaded to a USB drive. (Cross Country Model Only)

Logbook Up

A screen is provided to show the number of flights and total flight time for the day.

Pointer Zero Up

In the highly unlikely event that the pointer is not properly aligned to zero a means is provided to remove any offset.

Software Updates Up

User profiles, software updates and waypoint databases are copied to a USB drive. A simple interface allows the user to choose any or all of the options and upload them to the vario.

Cruise/Climb Switching Up

Switching can be automatic or manual. Three types of manual switching are supported: Flap, toggle, and momentary push-button. The toggle option allows pilots of non-flapped gliders to select cruise or climb using the kind of miniature toggle switch often mounted on the stick. The momentary switch option gives the pilot full control while maintaining the inherent advantages of an automatic system. This switch always puts the system into climb mode, and zeroes both averagers and both timers. Typically the pilot would use this switch when entering an exploratory turn in search of a thermal – if the pilot continues to circle the system remains in climb mode, if not it reverts to cruise mode. It will also be possible (using the Profile Editor) to make a conventional toggle switch behave like the push-button switch in that only a change, not the position of the switch matters.

Alarms Up

The ten-position connector has inputs for gear and spoiler microswitches.

- Flying (flying airspeed), spoilers open, gear up = gear alarm.
- Not flying (takeoff roll, low airspeed), spoilers open, gear down = spoiler alarm

ClearNav Vario Pricing Up

Refer to Pricing Page fo latest CNi pricing. (here)


Copyright©  ClearNav Inc.
2668 Husted Road Williams, CA  95987  USA
Phone: 530-473-5600