New Products
Ask the DEMON
bavarianDEMON TV
You are here:

Text FAQs (technical questions)

1. Is the tail rotor gyro also involved in the head control?

The system also requires information about the exact vertical axis rotation for the exact orienting of position - for instance after a vertical axis rotation - as well as for fast tilt adjustment (pirouette stabilization). Therefore the rotor gyro is also used for controlling the main rotor control.

2. What does the internal mixer serve for?

The control signals given by the auto pilot naturally require the same composites as the control signals given by the pilots depending on swashplate linkage. Therefore a board mixer is necessary.
Any active mixer in the transmitter must be deactivated at the same time. 

3. What does the 'Revo mix" option serve for?

A pleasant side effect results for the installed gyroscope due to the availability of the pitch channel, which the conventional tail rotor gyro does not offer: A revo mix is also possible in the heading hold mode (pitch tailpiece rotor admixture). The revo mix equalizes torque changes during pitch changes already in the making and thus offers additional support for the gyroscopes holding force.  This combination is optimal because the combination of heading hold and revo mix already reacts before yaw rotations occur, are measured and can be regulated again.

4. What to do if one or more of the head servo control functions is not properly mixable or is not functioning properly.

If the desired steering movements are not appearing at the head, for instance if they are going in the wrong direction or are completely unable to function, the most common cause is a false connection to the receiver (cable connection or channel definition), or hidden mixers are still operating in the transmitter.

5. Why is the internal path setting for nick/roll/pitch/ set to the mid-values by default?

These are empirical values from various tests for different models and linkage types.  
Changes for individual models are necessary and belong to the basic set-up for this.

6. What do high servo currents through "thin" connection cables mean?

The connection cables supplied are designed for 10A steady load and 12A short-term peak current.  There is no reason for concern.
Please look at instructions for connection variants.

7. What could be the cause if the tail rotor gyro does not hold the tailpiece precisely enough?

In the case of an unstable tailpiece or if the tailpiece in only sluggishly steerable in one direction a number of causes are conceivable and most notably a gyroscope sensitivity which is possibly too low.

  1. False mechanical neutral position: the tailpiece should be symmetrically designed and same path on the left and right.  
  2. The servo travel limiting in the rotor gyro menu could be too narrow.
  3. A previously used revo mixing in the transmitter was forgotten to be turned off.
  4. Severe temperature leaps, for instance from a warm car into a cold environment.  In the event of such temperature leaps wait until the device has acclimatised before turning it on.
  5. Strong vibrations particularly from combustion engines could disrupt the smooth operation of the tailpiece.

8. The rotor gyro sensitivity must be set very weak. Can this be?

Yes, this is possible. Since every helicopter is different, to begin with no general value can be specified. And comparisons with possible previously used rotor gyros (for instance when it was still a flybar helicopter) are particularly useless.  The conditions were entirely different before.
Furthermore the tailpiece sensitivity is very heavily dependant on the rotational speed.  The higher the rotational speed the lower the required tailpiece sensitivity.

9. Which tailpiece models are installed? Drift and temperature compensation?

Modern MEMS gyroscopes operate in the devices. As all gyroscopes these are also subject to a temperature drift . A company-developed temperature compensation is lodged in the system to protect against these drifts as best possible.

10. How can the horizontal mode also know its absolute angle of inclination while drifting?

The installed artificial horizon reacts to angle changes and to absolute neutral values.  For a normal "heading hold" tailpiece the smallest neutral deviations would continuously add up and a remaining tilt would result.  Furthermore, control signals would also add up and a one-time controlled tilt would be maintained.  However, a fundamentally different algorithm is installed in the bavarianDEMON for this purpose.
The difference from a normal 3-axis gyroscope is explained as follows: Since a normal tailpiece continuously adds up control signals as well as its rotation measurement it gets stuck in every controlled position.  It would not cancel a tilt. Two different functions operate in the bavarianDEMON horizon mode, namely the artificial horizon at one time and the control at one time which uses the horizon data and carries out an actual value/desired value comparison.  This is again reversed during an inverse flight attitude so that the control automatically operates in the correct direction in the supine position and thus produces a stable equilibrium.  
The fact that temperature drifts do not add up is due to the installed compensating control.  If minor deviations occur due to temperature drifts, only temporary and minor angle differences arise.  They can be conveniently balanced by simple control deflections in the horizontal mode, exactly like all external influences. Small control deflections are occasionally necessary anyhow in the horizon mode since a helicopter itself does not have any geographic fixed point even in the most precise horizontal position and always drifts somewhere.
In the horizontal mode it is important that after release of the control stick the horizontal position is constantly re-established. However, this is only applicable provided that instructions are followed.

11. Servo movements appear staircase-shaped. Is that O.K.?

There are two possible reasons here:

  1. non problematic:
    Many RC systems release servo pulses with a relatively slow frame rate.
    This can apply for 2.4 GHz systems.  If the servo movements appear staircase-shaped you will see exactly those positions which were actually transferred by the RC system, i.e., precisely in the transferred slow time screen. Since the bavarianDEMON controls servos faster than the receiver alone, the increments received on the servo are more distinct with bavarianDEMON.  Without bavarianDEMON servos accelerate a tiny little bit more sluggishly and therefore, mostly smooth away the increments.  The effect is completely irrelevant for steering in flight.
  2. tricky - careful please!
    There are older analogue servos which only tolerate a relatively slow pulse rate. If the bavarianDEMON’s relatively high pulse rate and possibly a supply voltage of more than 4 cells is still used simultaneously these servos could tend to vibrate. This vibration often only occurs during control stick movement and allow these to appear rasterized.
    If the servo continues to vibrate after a jerky control stick movement it shouldn't be used.

12. Which servos are permissible?

Supported are all current digital and analogue servos with default mid-pulse range (1.5 ms).
The heli systems since the X-series also support narrow pulse servos on the tail (not valid for 3A, 3D, RIGID, RIGID V.2).

13. For digital servos: What does subtle or rough servo vibration mean?

A slight operation is recognizable or audible primarily for fast digital servos by the bavarianDEMON, even when the model is standing still.  This is completely unproblematic and is due to either the output rate or due to small measurement fluctuations as they could appear with rotor gyros on the tailpiece servo.
The fact that 4 servos are now affected by this can of course boost power consumption of a receiver's rechargeable battery .  However, in practice this primarily occurs during the flight.  Then all "controlled" servos namely operate nearly continuously, i.e. more often than they would for "manual operation" of an average pilot for sure.  This additional work is incidentally reasonably independent of whether fluctuations are already registered on the ground or not - only you just don't hear them in flight.   The servo activity depends much more on whether control in flight works properly and if it is adjusted rather agile or rather quietly.  If the servos also work easily on the ground, this is hence insignificant.
This is different if a "rough" servo vibration should occur.  Reception disturbances are possibly at fault.

14. Are there modes for which the bavarianDEMON does not work?

Yes, but only to a very reasonable extent.  

  1. Regarding linkage: The H2 (2-item) linkage which was discarded in the 80's is not supported as well as the rare 135° variant which, however, can be replaced by 140° in the setting without compromises.
  2. Regarding control: Modes which slowly react to nick and roll in particular, possibly need an increase in horizontal sensitivity (and if necessary the roll and nick paths as well). Models with particularly high roll and nick rates may only be operated with bavarianDEMON if the roll and nick rate is limited to the maximal permitted gyroscope rotational speed (see technical data) via mechanical adjustment of linkage. The artificial horizon cannot tolerate faster rotational speeds.  They could cause a dangerous malfunction in this way.

15. Virtual swashplate rotation for rigid heads?

An angle displacement occurs between the roll and nick axis in many rigid heads.
bavarianDEMON has a built-in virtual SP torsion for this purpose and thus the possibility of an electronic compensation.
In addition, RIGID stabilization automatically corrects a percentage of deviations.  The original angle displacement should, however, constitute approx. 8-10° at most.
Alternatively the mechanical balance is formed by rotation on the swashplate driver, however, this is not always possible.  You should also take care that the push rods are not standing too diagonal otherwise increased rotary loads would affect the driver.

16. Why is such a large software foundation like .NET Framework necessary for a simple set-up software?

Unfortunately - .NET Framework is the current and future basis for software development under WINDOWS. It is correct that the installation of .NET Framework takes a few minutes; however, this only takes place on the computer once and is then a fixed component of the operating system.  All following application programs which use this (no matter small or large) are then installed quickly since basically only the executable program files must be copied.  This also applies, for example, to new versions of the bavarianDEMON.  .NET Framework is not an integral component of WINDOWS.  However it is already partly preinstalled on new computers. 

17. When do you have to send in the device for updates and upgrades?

Upgrades: all currently offered upgrade options are only performed directly at Captron.  This is due to the fact that the source code is handled or is reinstalled on the device.  Understandably enough, this cannot be contracted out.

Updates: are made on-line for 3X and 3SX  provided that at least firmware V.113 is  installed on the device. The Rigid V.2 must be sent in.

18. Direction drift in spite of "perfect" setting. Is this normal or is this an error in the system?

In general this is not a system error but rather one of the following errors:

  1. According to the diagnosis card the signals are not centred, thus no '0' over the beam. In other words, trimmed or potentiometer variance in the transmitter.
  2. Mechanically not optimally trimmed.  Caution: a perfectly horizontal swashplate is no guarantee for drift-free flying.  Perfect geometry doesn't always mean perfect mechanical setup.

19. Can I operate a Bavarian Demon on a flybar helicopter?

Yes, the FBL-electronics must simply be turned off via PC software for this purpose.  All other functions remain preserved.

20. Why does my SP hardly tilt when I tilt the helicopter for the system/direction check?

On the one hand the tilting of the swashplate for the gyroscope/direction test is severely dependent on the tailpiece sensitivity.  The smaller, the smaller the deflections.  Furthermore, mostly only very small deflections are necessary for a helicopter in order to maintain very agile behaviour.  In other words the swashplate only requires very mild deflections for regulation operations.

21. How do I connect master and slave from my ESC/BEC?

With cable harness: Master BEC, if coupled with ESC, to the receiver and slave to the bavarianDEMON. If BEC is separate, then connect all connections to the bavarianDEMON.
Always connect all connections to the bavarianDEMON: this applies to all other variants. There is a gas outlet especially for ESC which also carries out tension

The reason for this is not the bavarianDEMON this itself but rather the shortest path to the servos.  These are the main current consumers.

22. Can I simultaneously program all horizon and rescue functions and place them on various switches?

Yes, this works with modern transmitters with program mixers. Hence it is made possible to, for instance, place the rescue mode on a well accessible moment switch and at the same time to turn the pure horizon mode on and off via another switch and to even program various sensitivities where required, for instance on a 3-level switch.

© 2017 CAPTRON Electronic GmbH