Manuals:MB Plus:Flying

Tail gyro gain adjustment with transmitter

The tail gyro gain is adjusted by one of the transmitter‘s auxiliary channels. The more servo throw this channel produces, the higher the tail gyro gain will be. Additionally the direction of servo throw determines whether the gyro works in Normal-Rate mode or in HeadingLock mode. The color of the Status-LED indicates the selected mode when MICROBEAST PLUS is ready for operation. Purple indicates Normal-Rate mode and blue indicates HeadingLock mode. Additionally while adjusting the gain or shortly after the first start up, the current amount of gain is displayed by one of the menu LEDs for about 10 seconds. When the gain channel is centered, this will correspond to 0% gain indicated by LED A. In both modes, the maximum adjustable tail gain is 100% and will correspond to LED N. Please note that the actual percentage and sign of servo throw in the transmitter will depend on its brand and/or type.

For the first flight we suggest to start with medium gain not higher than LED G (LED D for 450 size helicopters and smaller) in HeadingLock mode. Low gain will cause the tail rotor control to feel weak and it will stop with overshoots. Increase the gain step by step and you will feel the tail having more and more precise stops, and hold better and better on jerky pitch inputs. If the gain gets too high, the stops will bounce back quickly and wagging will appear in fast forward or backward flight. In this case immediately reduce the gain! For optimum performance set the gain as high as possible, just before the tail rotor starts to wag in fast forward flight.

• Operation without using the auxiliary channel for tail gyro gain is not possible!
• When gain is close to point A (0% gain) the rudder servo will not perform full servo travel as the gyro is switched off. Do not attempt to fly in this condition!

Menu-LED	N	M	L	K	J	I	H	G	F	E	D	C	B	A		B	C	D	E	F	G	H	I	J	K	L	M	N
Gyro gain	100%	96%	88%	80%	72%	64%	56%	48%	40%	32%	24%	16%	8%	0%		8%	16%	24%	32%	40%	48%	56%	64%	72%	80%	88%	96%	100%
Auxiliary channel	-100	-96	-88	-80	-72	-64	-56	-48	-40	-32	-24	-16	-8	0		8	16	24	32	40	48	56	64	72	80	88	96	100
Gyro mode	Normal-Rate mode														HeadingLock mode

In Normal-Rate mode the tail gyro of MICROBEAST PLUS only acts as dampening that decelerates sudden rotations caused by external influences. Slow, constant rotational movements will not be compensated. Thus the tail does not drift in hover due to the main rotor torque, a perfect mechanical adjustment of the tail rotor is essential (see the section to Setup menu point D). But even with perfect mechanical adjustment you will always encounter some drift on the rudder axis due to crosswinds and the pilot has to constantly perform corrections when doing hovering flight. In high-speed flight on the other hand the tail will be aligned in flight direction by the wind, so curves can be flown very dynamically and the pilot doesn‘t have to constantly concentrate on controlling the rudder.

We recommend to use the HeadingLock mode. Here the tail is actively controlled by the gyro system. You will barely feel any external influences. By giving rudder stick input, the pilot only commands the gyro how fast it has to turn the tail. When the stick is in center position the tail gyro will ensure that the tail keeps locked into position by any means. This simplifies the control significantly. In hovering flight the beginner can fully concentrate on the control of cyclic and collective pitch and the advanced pilot can perform 3D - flight maneuvers such as backwards flying quite easily. The only disadvantage of HeadingLock-Mode is that the rudder must be steered by the pilot when flying curves. Otherwise the gyro will try to keep the tail aligned with the initial direction.

To gain better tail gyro performance also check for correct servo horn length. If the tail gain in general is very low and the rudder tends to oscillate very easily move the linkage ball on the servo horn further inwards to the center. If on the other hand you have a very large amount of tail gain and the tail gyro still does not seem to be capable to hold the tail rotor in any flight condition, move the linkage ball on the servo horn further out from the center, to get faster response speed when the gyro needs to control the rudder. Also you may use different (larger) tail rotor blades or higher tail rotor speed to gain better holding force.

Adjusting the dials

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To adjust the dials please only use the supplied plastic BEASTX adjustment tool to prevent damage to the dials!

Dial 1: Cyclic gain
The swash gyro gain (cyclic gain) can be set by dial 1 from 50% up to 150%. Turn dial 1 clockwise to increase the gain. The factory setting is horizontal which corresponds to 100% swashplate gain. For your first flights we suggest not changing this setting. However, when using very small helicopters (such as 250 or 450 size), reduce the cyclic gain by 3 marks (=75% gain) as with such small helicopters the control loop tends to overcompensate more easily.

In general the higher the gain, the harder the helicopter will stop after cyclic moves and the more stable and exact the helicopter will fly. But if the gain is too high, the helicopter will tend to oscillate at high frequency especially on the elevator axis. Due to their low mass, this behavior will occur sooner on small helicopters, so typically these do not need as much gain as large helicopters.

On the other hand, in case the gain is too low, the helicopter does not stop precisely and overshoots the more or less after a cyclic movement. Additionally, it feels unstable and sluggish in fast forward flight and when hovering. In general, low gain will allow the helicopter to have more life of its own and so it will not react to stick inputs as precise and immediate as the pilot expects it.

Ideally you set the gain to the sweet spot, at which the system reacts as precise and stable as possible without creating any negative effects.


Dial 2: Cyclic feed forward
This part mixes some amount of stick input directly to the servos, bypassing the control loop. If correctly adjusted, the feed forward relieves the control loop so it will work more efficiently by only having to make residual corrections. Factory setting of the dial is horizontal which provides a good setup in most cases. Turn dial 2 clockwise to increase the cyclic feed forward. This will cause more cyclic stick input going directly to aileron and elevator on the swashplate. Decreasing the direct stick feed forward will do the opposite.

In case the cyclic feed forward is set too high, the stick input will over control the cyclic input from the control loop. Eventually the control loop needs then to steer back and compensate the unwanted cyclic movement. Even though you get the impression to have a more direct and immediate control over the servos with high feed forward values, unwanted side effects may appear, like pitching back on cyclic stops and imprecise fast forward flight.

If the direct cyclic feed forward is too low, the helicopter will feel softer, slower and less "connected". The optimal point depends of many factors like blades, servos, head speed, size and mass of the helicopter. Ideally you can increase the feed forward just as high as possible without any negative effects happening. So you get a quite natural stick feeling and the control loop is supported as good as possible. Before adjusting the cyclic feed forward you should try to find the optimal maximum cyclic gain first (see above). Then adjust the cyclic feed forward and after that, you may have to adjust the cyclic gain once again, as both parameters interact to each other.

The cyclic feed forward does not affect the maximum rate of rotation! If the helicopter turns too slow, you should check the settings of the swashplate limiter in Setup menu point L, change the control behavior at Parameter menu point B or increase the servo travels or “Dual Rate“ setup of your transmitter.

Also to get a quicker and more aggressive response, increase the control behavior at Parameter menu point B (reducing expo and increasing the maximum rotation rate) and increase the cyclic response at Parameter menu point G. It is not recommended to increase the feed forward in this case, although it may produce a quicker servo movement and more direct stick feel at first glance. As described above this value is part of the control loop and you will get side effects as the control loop will not perform optimally, if you do not adjust this part as intended.

Dial 3: Tail gyro response
Turn dial 3 clockwise to increase the tail gyro response. Turning dial 3 counter clockwise will decrease it. Increasing the gyro response will cause a harder stop and quicker response to rudder stick inputs. But if the response is too high, the tail will bounce back after a hard stop and feel spongy when making fast direction changes. If the response is set too low on the other hand, the rudder control feels dull and stopping might be too soft. Ideally the tail should stop perfectly to the point without making any flapping noises.

Factory setting of the dial 3 is horizontal which provides a good setup in most cases. You have to make sure the maximum possible tail gyro gain has already been determined (see above) before adjusting the tail gyro response. Then after adjusting the tail gyro response you may have to adjust the tail gyro gain once again, as these parameters interact to each other.

Flying

After turning on the receiver power supply wait until MICROBEAST PLUS has fully initialized. This is displayed by a short movement of the swashplate servos. For initialization it is irrelevant whether the helicopter is leveled horizontally! Only important is that it is not moved as long as the calibration of the sensor positions takes place (LEDs lights A - G running). Also the control sticks of the transmitter must not be moved as long as MICROBEAST PLUS calibrates the stick center positions (LEDs H - N). If the initialization is not completed even after several minutes, read the Trouble shooting guide.

Like mentioned above the three dials should be turned to factory setting (centered horizontally), when using in small helicopters for safety reason dials 1 and 2 should be set to slightly below the center position. The tail gain channel should be set so that point G lights up, similar to approx. 50% tail gain adjustment. In micro or mini helicopters experience has shown that the gain must be lower (set to point D or 30%). Select the control behavior at Parameter menu point B to fit your flying style. If you‘re a beginner or unexperienced with flying flybarless helicopters you should highly decrease the maximum rotation rate, so change Parameter menu point B to “normal“ setting.

Before the first take off, make a stick direction check and again make sure that the sensors are correcting to the right direction when you tilt, roll or yaw the helicopter by hand.

It is normal that the swashplate might move back to its original position only slowly after a stick input and that the servos don’t run at the same speed as your sticks. In comparison to a flybared heli you are not directly controlling the servos anymore but controlling rotational rates like for fly-by-wire. The control of the servo is left to the control loop of MICROBEAST PLUS. The system will try to move the heli to the commanded directions and as the heli will not move while standing on the ground, the system may give maximum servo input, even if you do not move the sticks or the heli anymore, as the system will "remember" the command for some amount of time. Thus it is also normal when the tail gyro is operated in HeadingLock mode, that the rudder servo will stay in its end position after a rudder stick input or tail movement and that it does not always react immediately to a stick input. And for the same reason, it is also normal that the rudder servo runs to the endpoints even with small stick inputs.

Just before lift-off make sure that the swashplate is horizontal and that the tail pitch slider is near center. You can shortly switch the tail gyro to Normal-Rate mode, in this mode the rudder servo will center itself if the rudder stick is released. To center the swashplate move the cyclic stick to full deflection once.

Avoid excessive steering during lift-off, otherwise the helicopter may tip over as it can't move as long as it's still standing on the ground (as decribed above the system tries to move the helicopter by applying more and more servo movement)! The best way is to give a fair and direct collective pitch input to lift the helicopter quickly up into the air. This demands some re-education if you have only flown flybared helicopters before.

Once airborne at first you should adjust and try to find the maximum possible amount of tail gyro and cyclic gain (dial 1). Then you may optimize the tail gyro by adjusting Parameter menu point D in case you're operating the tail gyro in HeadingLock mode and adjust the response of the tail gyro using dial 3. Additionally you may need to adjust the Cyclic feed forward (dial 2) and Parameter menu point C. If the helicopter does react very aggressive to stick inputs, change the Control behavior at Parameter menu point B to a lower adjustment and/or reduce stick throws (servo throws) in the transmitter for the specific functions. Likewise increase the stick throws and/or Parameter menu point B, if the reaction is too slow and gentle for you. When the control loop is well adjusted, you can additionally use Parameter menu points G and H to fit your flying style and stick feeling. To support the tail gyro you can activate the Torque precompensation at Parameter menu point F if necessary.