SL720 GYRO/PC INTERFACE MANUAL
INTRODUCTION
The SL720 gyro has a 'PC' port that allows the internal settings of the gyro to be examined and adjusted to users' requirements.
For most users the pre-loaded default settings of the SL720 will be satisfactory. However where the servo being used is a
Futaba 9251 which uses 760us (short) communications pulses users will need to use the PC interface to select the appropriate
options for this servo before it is connected to the gyro. The gyro is also capable of being used for many non-standard
applications (e.g. fixed wing models, camera stabilisation, robotics, etc.) that are generally outside the scope of this manual.
However, if you have such an application please contact us via email at: [email protected]. and we will attempt to advise
you.
Before making adjustments to the internal parameters of the gyro we strongly recommend that you
first get your model
performing well with the factory default settings
. In our experience this is always possible. If you have major handling
problems with your model look for the cause in your radio set-up, tail linkage adjustment, friction or slop, tail blade length,
servo choice, battery condition, gyro location, static discharges, etc.
Trying to cure such defects by internal adjustments of
the gyro will be a frustrating waste of time.
The PC interface is a powerful diagnostic tool. By showing you the values of the
Mid Stick pulse length, Throw limits, Quick-trim offset, etc. it allows you to accurately check the radio set up and linkage
adjustment.
Basic optimisation
Once you have your model responding well to the default settings set the
servo speed parameter
to match the value for the
servo you are using. Then do the pirouette start tests and adjust the
pirouette start and stop
values as described in the
general parameters section. Then you may want to adjust the
Linear and Exponential stick sensitivities and the dead-band
to get the stick feel to your liking. Since these have independent values for Mode0 and Mode1 you can set up a different stick
‘feel’ for each mode. You should already have obtained reasonably well matched stops from fast, full stick, pirouettes before
tackling the internal parameters but the stop tracking controls (
left and right stop gains
) are useful in adjusting the stop
quality from lower pirouette speeds.
Further optimisation
Further optimisation should centre on the relative amounts of
conventional gain
, the
heading lock gain
, and in some cases,
acceleration gain
. As a general rule the faster the servo the higher the heading lock gain that can be used and the slower the
servo the lower the heading lock gain should be. The helicopter has a significant impact on this. An easily driven tail linkage
will allow the servo to approach its no-load speed. Conversely linkage and hub bearing friction can significantly slow the
servo.
Small electric helicopters
present a special case because these models react quickly in yaw, their production tolerences
give less precise pitch control, and micro servos have relatively lower performance than standard size servos. Improvement can
often be gained in such helicopters by reducing the heading lock gain, in some cases to between half and three quarters of the
default value. Increasing the acceleration gain to about 120 has also been found useful in cases where the model exhibits a
vagueness in heading or wags very slowly in the hover.
Remember that after changing the internal gain values you will usually need to re-adjust the transmitter gain.
The remaining parameters determine the detailed dynamics of the gyro system. Given the number of these variables as well as
the many aspects of the helicopter (tail blade size, engine performance, servo speed, etc.) that influence the characteristics of
the helicopter in yaw it is not possible to give a simple recipe for further optimising the gyro for your model. The parameters
have complex interactions so that the optimum value of, say, Acceleration gain is affected by a change in the Heading Lock
gain and vice versa. So before attempting adjustments it is vital that you have the model in perfect mechanical condition and
performing consistently. You should then try making small adjustments to the default settings and observe their effects.
In arriving at the factory default settings we found it useful to set the two modes to nearly identical settings differing only in,
say the value of the Acceleration gain value. By switching between the two modes we were able to see quite small changes and
'home in' on the optimum. Careful note-taking is vital to prevent confusion in this process! An observer taking notes on a clip
board or Dictaphone is very useful. Once you have used this technique to get one good mode you can then apply the same
method to optimise your second flight mode.
INSTALLING THE INTERFACE SOFTWARE ON YOUR PC
To install simply insert the distribution disk into your PC and use 'Windows Explorer' or 'My Computer' to copy the 'SL720'
folder (and its contents) from the distribution disk to the hard disk of your PC. For convenience, create a short cut to the
interface program as follows:-
Right click on your desktop.
Select 'New' and ' Shortcut'.
Click on 'Browse' and in the resulting window double click on the 'SL720' folder on your hard disk.
In the window that now appears double click on the 'SL720' application.
Then click 'Next', 'Next', and 'Finish' at successive stages to complete the shortcut.
RUNNING THE INTERFACE SOFTWARE
Once the software has been installed on your PC follow these steps to connect to your gyro.
1. CONNECT THE GYRO INTERFACE CABLE TO YOUR PC
