THE ZANDER SR820 IN THE DG-300

Compiled by John Ashford

The Zander SR820 is one of the new family of air data computers which have become popular with serious competition and cross-country pilots in recent years. It consists of a computing and main display unit, an electric variometer meter, two potentiometers to set expected climb rate (Macready) and Headwind/Tailwind components and a remote switch on the control column for you to tell the Zander whether you are climbing or cruising.

The Zander computes height required to achieve a glide to a pre-set waypoint distance. It takes into account the performance characteristics of the glider which can be modified for wing loading and the effect of bugs or rain on the wings. Like all final glide computers, electronic or cardboard, the numbers displayed depend on the Macready setting and you can see these changing when you fiddle with the Macready and/or Wind potentiometers. It is therefore essential that you set the potentiometers correctly for the conditions which exist, particularly when it comes time for that final glide home. The Zander displays the average rate of climb of the thermal you are in as well as the instantaneous vario reading, this ought to stop you from overestimating actual achieved climb rates. The averager only works for climbs when the remote switch on the column is up. In this case the average rate of climb is marked M (Macready). When the remote switch is down, the Zander assumes you are cruising and proceeds to compute and display a lot of useful information, this display is called "Page 1"

1. The distance to go will be reduced by the distance you fly through the air adjusted for wind strength, set by you with the "Wind" potentiometer.
2. The height required for the distance to go for the current Macready and Wind setting is computed and displayed.
3. The average Netto is displayed, this is what the air is doing irrespective of what the glider is doing. in this case the average netto is marked n.
4. The variometer meter now shows the instantaneous Relative Netto, this is what climb rate you can expect if you stop and thermal. It is in fact Netto minus 0.8 m/sec which is the average sink rate of most gliders when thermalling. (Netto is german for nett)
5. An audible tone is emitted to indicate whether you are flying too fast or too slow. Best speed to fly is not displayed, the audible tone is the only "Speed Director".

The Zander allows for up to 9 waypoints (legs) to be pre-programmed into it. These are transferred to Page 1 in ascending order each time you flip the STOP/START switch where the Zander goes to work on it as you cruise. The distance to go is the waypoint distance less the distance flown through the air adjusted for the wind.

By selecting a few map points along each leg you can soon get the wind set accurately by changing the "WIND" setting until the displayed distance to go coincides with the real distance to go. The effect of the wind has to be put in at each leg, the Zander has no way of knowing which direction it is coming from.

The Zander is a simple device to use but you can be jerked around by it if you:

1. Forget to switch from climb to cruise and back again.
2. Forget to change the wing loading after dumping water.
3. Have the Macready or lind settings grossly wrong.
4. Call out the wrong waypoint for the current leg.

The Zander will not make you fly better and unless you can thermal properly, like it is second nature to you, you mill probably get worse. Newcomers to the DG-300 should learn to fly the glider properly first, worry about the electronic gadgetry later.

Learning to use the Zander is best accomplished by sitting in the glider away from surrounding experts and fiddlers and operating the thing for about half an hour using these notes until you are satisfied you understand the leaning of the display and the effect of the various switches.

If you do not learn how to use the device on the ground you will never learn it in the air and you will become a COLLISION HAZARD. It is a good idea to have a few flights just using the variometer meter and switching from climb to cruise, forget the waypoints, wing loading and best L/D, they can come later, don't become a clock watcher or switch fiddler, keep your eyes out of the cockpit as much as possible.

The display, being a liquid crystal, is sensitive to strong sunlight and you should not leave the glider with the sun shining directly onto the display. This is particularly important in the morning and evening when the sun is low on the horizon. The display will recover after about half an hour out of the sun.

THE SWITCHES

1. The yellow Cursor switch moves a flashing bar "_" under the display you are about to interfere with. The switch moves down and up for cursor right and left.
2. The numbers can be altered by single digits ±1 or ten at a time using ±10. The numbers go up or down depending on whether you hold the switch down or up and will "run" if you keep the switch held in either position. These switches are green.
3. There are five displays called pages and the orange page control moves you through to the next page when switched down or immediately back to page one if moved up. Page 1 is nearly always in use.

• Page 2. The wing loading of the glider and some code indicating how the Zander has been configured is displayed on this page. If you alter the configuration the Zander will not perform the functions as described in these notes and you may as well turn it off so don't do it! You need to alter the wing loading after you have dumped water or after refilling ready for the next flight. The DG-300 has wing loadings from 50 Kg/m² down to 32 Kg/m² depending on your weight and amount of water carried.
• Page 3. This display shows, the battery voltage, the outside air temperature (not connected) and the waypoints. You can alter the waypoints by using the cursor and the ±1, ±10 switches
• Page 4. This page is a display only and gives you statistics about your flight. Time on task, distance flown (without wind effect), average speed, total height gained, average climb rate and percentage of the time spent climbing are all available for analysis after the flight.
• Page 5. This page shows the various addresses in the memory and will only confuse you if you fool around with them so don't otherwise you might mess up the whole thing.

The audible tone for the electric variometer can be adjusted for volume using the grey switch. The volume can be adjusted for the climb and cruise mode independently to suit your own preference or partial deafness. The cruise mode usually needs a louder volume setting than climb if you use a lot of ventilation due to the higher air noise in the cockpit.

The last switch in the row immediately over the top of the display duplicates the climb/cruise switch on the column and is coloured blue. If the switch on the column fails you can use the panel switch up for climb, down for cruise, but you must leave it set in the neutral position for the column switch to work at all. Check this often as it is easily moved up or down it you or others have been fiddling.

The two other switches on the top of the display unit are the white Start/Stop switch and the red On/Off switch. The "START" position will set the distance and time counters running and there after each time you operate it will call out the next waypoint and display it on page one. In the stop position the counters are halted but the variometer functions normally and all other displays continue working. If you need to do a restart in a competition you can reset the counters by holding the cursor and the page switch down together momentarily. You should have the Start/Stop switch set to "STOP" before doing this so that on your restart, when you press "START" the first waypoint will come out on display.

THE DISPLAYS

MAIN DISPLAY AND CONTROL UNIT SHOWING TYPICAL PAGE ONE DATA
Top row: 97 km to waypoint "D". 700 ft, safety ht."F" 42:1 best L/D. "E"	Second row: average rate of climb "M" height required for "D"&"F" total time on task hrs:mins

SAMPLE PAGE DATA

 097D  0700F 42E
 2.2M 15786 1:43

 097D  0700F 42E
-0.8n 15786 1:43

 097D  0700F 42E
-0.8n 15786 1:43

 097D  0700F 42E
-0.8n 15786 1:43

 097D  0700F 42E
-0.8n 15786 stop

 50L         ART
 1.13k       010

12.5Volt -39.5°6
WP1: 326km

03:57 0741d 113v
98.6h 3.24m 023%

OPERATION

FLIGHT PREPARATION

1. Set Start/Stop to STOP
2. Switch Zander on, Page 1 will be displayed.
3. Hold down cursor and page switch together, counters will be reset to zero.
4. Check mode switch on right is in neutral, check column switch changes display from M when up to n when down, return to up and check vario is working by normal TE check for mechanical vario at same time.
5. Move cursor to F and set field safety height using ±10.
6. Examine L/D, if incorrect move cursor to E and change to desired value using ±1.
7. Change to page 2.
8. Examine wing loading, if incorrect move cursor to L and change to desired value using ±1, ±10. Do not confuse the glide angle on Page 1 with the wing loading on Page 2.
9. Change to Page 3.
10. Set waypoints using cursor and ±1, ±10 switches.
11. Check battery voltage is ok. Below 11 volts the Zander shows "batt" where the page 1 display normally shows the elapsed time or "stop".

IN FLIGHT

1. At start of task, set Stop/Start switch to "START".
2. Switch column switch, up = climb, down = cruise.
3. After flying same distance, check displayed distance to go with distance to go from your map, alter Wind potentiometer so that both coincide. Check this at suitable map points and remember to change the wind allowance when you change headings at a new waypoint.
4. Set Macready potentiometer to the average expected rate of climb from when you stop to circle or when you head off on track again.
5. Reduce maximum L/D ratio if wings get wet or bugs on them.
6. If you dump water remember to change the wing loading (Page 2 first item on display). Do not confuse the maximum glide angle on Page 1 with the wing loading on Page 2.

RESTART

If you need to restart the task without disturbing waypoints:

1. Set Stop/Start to "STOP", notice that time reads "stop".
2. Press Cursor & Page switches down together momentarily (if you hold them down too long it will clear the waypoints also).
3. Set Stop/Start to "START". When ready to start again. Notice waypoint 1 will be called back to the page one display, time starts counting from zero.

Return to Newsletter Page.
Return to Member Services.