Pattern Flying

Pattern Flying

The RC Flight Assist System was designed for practicing pattern flying. The flight area is determined by the distance between the pilot and flight line and the angle as described in the picture:

areatop2            areaside

The RCFA allows pilot to maintain airplane in the proper flight plane. This is possible by sending the airplane position to the pilot’s telemetry receiver. The receiver converts the data into sound patterns which clearly indicates the distance from the pilot to the airplane. If the airplane is too close or too far to the flight plane, too high or too much to the left or right side (exceed margins) the pilot will be noticed in real-time. At the same time the transmitter can memorise the GPS path in the kml which can be viewed with Google Earth. Each flight will be stored in separate file. The flight area indicators are also stored along with the fly path.

The pilot can set custom area dimensions and flight plane width or use defaults (150m/60 degrees). Also some alarms (like exceed margins or too high altitude) can be disabled or enabled. All options can be set in text file rcfa.ini stored in SD Card.

To simplify the usage, the RCFA has option to automatically start and stop GPS Logger. The only thing the pilot must do is to wait for a GPS Fix and then to determine two points on the ground (P1 and P2). The P1 is the pilots position and P2 is the direction to the flight line. Both points are set by two buttons on the transmitter. To do this, pilot must go to the point where the airplane will be controlled from, and press button A. Then go few meters away (10-20 metes is usually enough) in the direction of flight line and press button B. After this, the system will calculate all remaining coordinates of the flight area and play certain music so the pilot will know that everything is ready to start flying.

The system will store last P1 and P2 coordinates in internal memory so it is not necessary to repeat this step every time from the beginning. Next time on the airfield, pilot is ready to start flying just after GPS Fix. The other way to determine the flight area is to put P1 and P2 coordinates directly in the rcfa.ini file but the ini setup overwrites coordinates from device’s internal memory.


GPS Logger

GPS Logger

RC Flight Assist can be used as a GPS Logger. The data is stored on Micro SD card in kml format, which can be opened directly in Google Earth. The fly path is visualized as a line in 3D space as an animated track. The logger is controled by several options. At First the stream speed frequency can be changed, than means the coordinates can be saved every 0.5-60 seconds. Secondly, the GPS data acquiring speed can be changed as 1, 5 or 10 times per second. You can also manually set the accurate reference altitude thus the plot will be at exact height. The altitude measurement rely on high accurate barometrer sensor MPL3115A2 but it is not obligatory to be used. In case of barometer missing, the altitude data is acquired from GPS. The Logger can work in two mode.

Automatic mode

Automatic mode was designed for acrobatic flights, so the pilot do not have to remember to enable or disable Logger before each flight. The logger will start when the airplane fly in the flight zone, and stop on leaving it.

Manual mode

Manual mode along with attached barometer make of RCFA a high quality GPS Logger. In this mode the Logger must be enabled and disabled manually everytime by pressing relevant buttons on the transmitter. To reduce energy drain, the radio module can be turned off.


RCFA Gallery

RC Flight Assist in F3A airplane


Tracking System – F3A flight


GPS logger – free flight


Concept work


RCFA user setups

RC Flight Assist Telemetry System

RC Flight Assist Telemetry System

Welcome to LittleCircuit

We present to you one of a kind telemetry system for RC pilots. The RC Flight Assist (RCFA) was designed especially for outdoor pattern flying like F3A or F3M class. The system allows better control over airplane during acrobatics. It implements radio telemetry mechanism that indicates the position inside the flight area with high accuracy. With RCFA the pilot is able to stay in the proper position on the sky resulting better handling and improved skills. The system was tested in cooperation with best polish F3A pilot of the year 2015.

How does it work?

The RCFA system includes two separate electronic devices which are Transmitter and Receiver. Primary role of the Transmitter is to get 3D or 2D position from GPS and altimeter sensors and send the data to the pilot’s Receiver. The Receiver converts the signal into nice sound patterns. The pilot can use build-in sound speaker or headphones to hear telemetry information.

The basic usage of the RCFA is to define two points on the ground to determine flight area. First point (P1) is the pilot’s position – where the airplane will be controlled from. Second point (P2) is the direction to the flight line where the airplane shall be controlled in. These points can be set by walking with the RCFA to desired position on the airfield or by writting coordinates in configuration file (rcfa.ini). The optimal distance between P1 and P2 relay on GPS signal strength and usually don’t have to be more than 20m.


Points P1 and P2 are set within the Transmitter. After it is done, the RCFA system automatically calculates remaining flight area coordinates regarding preset options: the ideal Flight Line (marked with points A, B and C), the Green Zone (green color) and Flight Area (blue color). The pilot’s job is to keep the airplane between the green rectangles:


During a flight the RCFA Receiver generates certain tones that changes accordingly to airplane distance from the green zone. It allows pilot to fast react and steer the airplane to the desired position on the sky. The pilot will know exactly how far from flight line is and also if the airplane is ahead or behind the Green Zone, too high, or too far to the left or right side of Flight Area.


When the flight is over the system will calculate score according to time in the zone and overall flight time. It is automatically stored in kml file. The logger file can be instantly opened in Google Earth (Windows or Linux) to examin the flight and check the scoring.

What else the RCFA can do?

GPS Logger

The system is highly customizable. The user can chage any parameter like distance from pilot to the flight line, area angle, flight plane width and many more (nearly 30 options). It has integrated MicroSD slot for memory card, which is used to store and read area parameters from but also to write positon data as high accurate GPS Logger.

The System implements unique filter algorithms thus the GPS data stream and altitude are high accurate, moreover the RCFA allows to use barometer for even more accurate altitude measurement. It’s accuracy is enough to verify every single figure on the 3D acrobatic fly path. The Logger writes data directly in kml format which can be instantly open in Google Earth software.

Real-time tracking

Another advantage of the RCFA is the ability to stream data to the Receiver about current 3D coordinates through RX/TX interface (USB2TTL). The data stream (longitude, latitude and altitude) can be read and visualized on PC in real-time. This can be organized in several ways. Depending on barometer availability the altitude data can be taken from GPS or barometer. User can choose either the absolute (mean sea level) or relative (to pilots position) altitude readings.


Next feature of RCFA is variometer, which can be used as well in gliders as in any other kind of RC airplanes. The variometer can use GPS data or barometer to indicate altitude changes. The data is send to the Receiver allowing the pilot to control descending or ascending in real-time.