Autopilot Operating Instructions

External view of the auto and box.  The auto control board is on the right. The 'handles' at each end are not intended to be carrying handles, just to locate supporting straps.

Box open, below.  From left to right there is a non operational thermistor, an altimeter, a Ball 400 variometer, and the auto control board. The auto control board has the appearance of being well used because, well, it has been.  Maybe I should have added a clear perspex cover directly above the board to keep it looking as neat and tidy as when it was new!  I could have made a proper box too but never got around to it. Same applies to the bell wire on the photo. But it all works.

The external wire running from the top centre of the control board (the looped bell wire on the photo) is the supply for the 12v electric valve on the burner.  There is a connector which would link to the wire running to the valve.

Just a small point about the altimeter. I flew with digital altimeter as well, but I found the dial type a great deal easier to use higher up, on long flights.

The vario
The on/off switch for the Ball varo is bottom right of the dial, switch up and maximum scale deflection is 300 fpm, switch down for maximum scale deflection of 1500 fpm.  The vario batteries last an extremely long time, something like a year if the vario is left switched on all the time, but best to switch off when not in use! Should replacements be needed unscrew the bottom and just clip in a new pair.  The silver coloured knob lower left of the auto is the fine adjust, when switched on it should either read zero or be adjusted to zero.  With the vario in the 300 fpm scale the fine adjust knob should swing the needle between +7 and -7 units.  If it is a much lesser swing the new vario batteries are needed. (The swing is much less on the 1500 fpm setting)  If the swing is biased one way or the other then the course adjust should be utilised to centre the swing, by moving a red disk at the bottom of the vario, accessed through the oval shaped hole underneath. the burn button light will glow dimly
The fine adjust rarely needs adjustment, never in flight, and the coarse adjust is very rarely used.  I have explained this in some detail however since adjustment of the fine adjust knob is extremely useful in simulating the conditions experienced in flight and demonstrating, on the ground, exactly how the auto behaves in flight.  More on this later.

The Model 400 Ball vario went out of production many years ago, the replacement models were not so sensitive, and the company itself went out of business several years ago.

The Auto Battery and Charger Socket
The charger socket is top left of the auto control board.  The auto battery is a standard 12 volt 2.8 Ah non spillable battery. (Certified for safe transport in aircraft!) New September 2012.  Charge using any car type 12v battery charger. With the auto is a short lead one end fitting in the charger socket, the other end terminating in a small block to take the clips on the leads from a battery charger.  As with any battery it is important to connect positive to positive hence the the block is coloured red/black.

If the auto is switched on while the battery is being charged, the red burn button light will initially light, to signify burner operation, then continue to glow dimly. When absolutely fully charged, this light will contune to glow dimly even when the charger is disconnected.   When this light comes like this on it is unnecessary to charge further.  Just like a car battery though, this battery will not be unduly harmed if it is charged for too long with any modern charger.

Reset button
Top right of the control board. There are cutouts incorporated in the system, in case of overload or short circuit in the electric valve or leads, correct, then press the reset.

Press on/off toggle switch and light
Situated just below the charger socket.  Pressing turns it on, pressing again turns it off.

When it is on there will be a light immediately below the switch. Red when the system is active, green when it is not, which is when the balloon is climbing at a rate faster than set on the threshold.  Normally, for level flight, the threshold will be set at zero.

Burn button and light.
To the right of the on/off switch.  Whenever the burner is activated this light shows red.  Since when you are flying it is pretty easy to tell if the burner is activated, this light is really most useful for a ground simulation.  You can see the results of changing the flight characteristics with the vario fine control, or the operation of the various backup systems.

The burn button will allow you to put in a manual burn.  This will almost never be used when you are flying on the autopilot, but can sometimes be useful if you want to fly the balloon manually, using the electric valve, for example when landing.  The burn button will operate whenever you want but to be sure the auto does not take over when you want to fly manually, the set knob, below, should be set to maximum descent.

The set knob
Central, below the above two buttons.  With this button you can set the auto for level flight, or a rate of climb/descent from over 1000 fpm climb to over 1000 fpm descent. (Note.  Setting the auto to these numbers does NOT mean your balloon can tolerate those speeds!)   For level flight, the adjuster knob will point to 9 o'clock, it is self locating.  For a climb of about 5 units the adjuster will point to around 12 o'clock, and for 5 units descent will point to around 6 o'clock.  Here the auto is reading the units on the vario, not the actual rate of climb or descent.  5 units on the 300 scale will produce 1/3 of 300 i.e. 100 fpm whereas 5 units on the 1500 scale will produce 1/3 of 1500 fpm i.e. 500 fpm.

Should you forget to turn the auto off, or to change the setting to allow a high descent rate when landing, when say you have been cruising down to a landing spot with the auto on 100 fpm descent and you want to come in faster to actually land, then should the burner fire when you don't want it to, the the fastest, easiest, and quickest way to cut the burner is to turn this control maximum anticlockwise.  It is marked 'turn to stop'.  It will cut the burner instantly.

The set burn length knob
This can be set from 1 seconds to 20 seconds.  Setting this is trial and error and will take about 3 burns to get it close. Once set up for a particular balloon/burner combination it will not take much adjustment for subsequent flights. I found about 5 or 8 seconds was generally about right but it varies with the configuration of the balloon and of course whether you have the burner set up with the link valve open or closed.  The burn length does not need to be set precisely, as long as it is enough to get you through the threshold that is OK.  Of course, the shorter you make it, the flatter your flight will be,  but the more you risk that the atmospheric conditions will change slightly and the backup procedures will be brought into play.

The set search knob.
As explained in the theory, after every burn is finished the search system comes into action.  If after a set time, the burn has been insufficient to cause the balloon to climb back through the threshold, another burn will be made.  The search time should start close to maximum when setting up the auto, then this period reduced so that it is just longer than the time required to bring the balloon back through the threshold.  I really can't do any better than to quote what I wrote earlier "Since this is only a backup system it's setting is neither critical nor urgent. If it fires earlier than it should you just extend the period a touch. If it fires too late then when it does fire the automatic firing of the burner will alert you that there is a problem, time to think about putting in an extra manual burn and reducing the delay period."  But just like the set burn length control, once set up for a particular balloon/burner combination it will not need much further adjustment for subsequent flights.

Set it to work.  The ground test, or demonstration.
No need to connect the electric valve initially, until you want to test the whole set up. Switch on the vario, on the fine setting, up, to 300 fpm max scale deflection, marked 3. Put the fine adjust on zero. Switch on auto, put the set knob to level flight, that is, 9 o'clock.  If the active/inactive light is showing red turn the vario adjust button a smidgeon clockwise until it turns green. Put the set burn length to 2 or 3 seconds (a little above the minimum) and the search to maybe 10 seconds. Now if you sit and watch it nothing will happen, because the auto thinks you are above the threshold, as you are.  While you are above the threshold the auto will continue to do nothing, as it thinks you are climbing and the setting is for level flight so no need to burn.  If you want to fly level you don't generally burn when you are climbing.

Now turn the vario adjust a smidgeon anti clockwise and all is action. The vario needle shows a very slight descent, the active/inactive light turns red, active. The burn light comes on for a couple of seconds.  Now continue to turn slowly to simulate rate of descent gradually increasing as you give a little time for the burn to have an effect, then start to turn the vario adjust clockwise as you simulate the burn having it's effect on the balloon and the rate of descent reducing until the vario shows zero.  The balloon is now rounding out at the bottom of the sine wave.  As you continue to slowly turn the adjust clockwise this simulates the rate of ascent increasing as though the burn was now continuing to have it's effect. Eventually the burn will have no effect and the balloon will start to cool.  Turn the adjust anticlockwise to simulate the rate of ascent decreasing until eventually the rate of ascent reaches zero - zero on the vario, and simulating the balloon rounding out at top of the sine wave. Go back to the start of this paragraph to repeat for the next simulated burn.
Then leave the needle a few moments longer in the red, active zone.  The backup system will automatically bring in another burn depending on your time setting.

Now to simulate a climb using the auto.  Move the set knob to about the '+' of +6 say 11 o'clock, the light will be red since you are below the threshold.  If it wasn't already red the system will put in a burn, which is fine since you wanted to initiate a climb.  Move the fine adjust up to 5 on the vario and then use the fine adjust to swing the needle above and below 5 just as previously.  The threshold will now be 5 instead of 0, otherwise the auto will behave as previously.  Instead of simulating flying on a level sine wave, you are now simulating a rising sine wave, climbing at 5 units, 100 fpm.  

In practice I rarely used this rate of climb on the auto, but 5 units with the vario set at 15, 1500 fpm maximimum scale deflection, will give 500 fpm climb, and that is a rate of climb difficult to hold manually (since the autopilot in our head is set to hold level flight!)  With such a climb, and a burn length set to give optimum performance in level flight, in actual practice a single burn may not be sufficient to get and hold this rate of climb, so the search, or backup system, may be called into operation to put in a second burn. In practice I have sometimes reduced the search timer a touch for optimum climb rates.  So for fast climb or descents use the 15 scale, but for level flight the 3 scale.

Note: it is very easy to forget to turn off the vario after running a ground test, or demo!

In practice, in level flight,  I very rarely had the backup system operate,  but it's the question everyone asks, what if the burn isn't enough to get it past the threshold?  Correctly set up, for level flight, you won't need it.  But it's there. Just in case.............

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