Adding a gyro to an airplane is not especially difficult but it is an involved process.
Why a gyro?
Like digital radios with mixes, trimming and exponential, a gyro is a tool that assists in the stability of RC flight. My chief interest was the ability fly in higher wind than I usually would.
I chose the Aura 8 based on price, availability, and positive reviews.
A compatible receiver (S.Bus for Futaba users) and digital servos are the recommended route. My Pulse 125 has a basic receiver and analog servos, so the PWM method was used. The connection diagram is below; note that receiver ports 1, 2, 4 and 5 connect to Aura 8 ports S1 to S4, respectively, and the Aura ports S5 to S8 connect to the servos for the left aileron, right aileron, elevators and rudder, respectively. One limitation of the PWM connections is that only one elevator servo can be connected.
The unit can be installed upright or inverted in a lateral or longitudinal axis, as long as it is at right angles to the direction of flight. The orientation is configured in the Aura app afterwards. The location that made the best sense in this airframe is inverted and facing forward (the nose of the airplane is off to the left, outside the photo).
Because the Aura Config Tool for PC connects from a PC to the Aura 8 unit via a Micro USB port, I decided to extend the port so the connection could be made outside the airplane. I found a Micro USB panel mount extension cable that did the trick.
There was a slot in the Pulse 125's frame that was well suited.
It was a matter of removing the covering and connecting the cable to the Aura 8.
To program the Aura 8, I made a copy of the Pulse 125 profile in my transmitter, then set it up as follows:
- End points:
- Aileron / Elevator / Rudder: 125%
- Throttle, channel 5: 100%
- Sub trim: neutral
- Trim levers: neutral
- Channel 5: assigned to 3-position switch SD, which I typically use for high/low rates)
- Reversing: all channels normal
The throttle was trimmed and channel 5 reversed after the Aura 8 configuration, as shown in the photos below.
Aura Config Tool
This is a free, downloadable PC tool. Installed on a laptop and connected to the Aura 8, it sllows to set general properties, mixes, control modes, flight modes and servo ports. Here is the opening setup screen for the Pulse.
There are too many screens to show all of them here. A copy of the file is online to download at 25_v1p4_cf.acf.
Once the file is created, it can be saved to the Aura 8 by connecting it to a PC via USB.
My Aura 8 is configured for three flight modes:
- Gyro off, low rate
- Low gain, low rate
- High gain, high rate
Testing on the ground is pretty simple. With the airplane assembled and the transmitter on:
- Pivot the airplane on its roll axis; the ailerons should move slightly in the opposite direction
- Pivot the airplane on its pitch axis; the elevators should move slightly in the opposite direction
- Pivot the airplane on its yaw axis; the rudder should move slightly in the opposite direction
The first flight with the Aura 8 was on a windy April day in 2018, and the gyro was an enormous help. Afterwards I had to trim in some down elevator, which was done on the transmitter with the airplane power off. This was necessary so the gyro would not see the trim as controlled input during flight. Once the airplane power was turned back on, the gyro saw the addition trim as the neutral position.
After a few flights my usual flight mode is 2 (low gain, low rate).
I liked the experience so much that I picked up a couple for two other planes.