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Posted by jociz | Dec 17, 2015 @ 08:12 AM | 3,288 Views
This is a quadro copter, frame of which is made of balsa wood. The balsa is very light weight build material. Should wood frame get broken or damaged, it is much easier and cheaper to repair.
It has another advantage over "legacy" plastic-composite frame, the vibration brought to flight controller is lower.
First flight video

Fa-Copter: H500 balsa wood frame, Mini APM Pro , 2212 920kv motor , 1045 props, 5200mAh 3s LiPo, Frsky Taranis TX, X6R
weight of frame: 160gr, total weight without battery: 710gr
flight time with 5200mAh: 25mins
Posted by jociz | Nov 14, 2015 @ 03:42 PM | 4,650 Views
Brushless motor and esc may become overheated during flight. Overheated component can result in abrupt falling out of sky in case of multi rotor machine. This may involve fatal consequence as well. It is not easy to assess in advance how the combination of particular brushless motor, ESC, propeller and weight of machine will behave with some environmental condition (ambient temperature, wind, air pressure, etc.).
Therefore it is good to know the temperatures of brushless motor and ESC along with APM MAVLink information during flight.

MAVLink information and additional temperature sensors are displayed on FrSky Taranis using Arduino. This solution uses Arduino to convert MAVLink telemetry protocol to FrSky smart port protocol. Arduino plays a role of bridge between the telemetry UART port of APM and smart port of FrSky radio receiver (X8R, X6R, X4R). Communication between Arduino and MAVLink source (APM) is implemented via hardware UART of Arduino. FrSky smart port is connected to a digital pin that SoftwareSerial drives. Besides MAVLink, Arduino provides 2 temperatures for smart port. Temperature is measured with NTC termistors. NTC: 10K 5% Thin Film Thermistor B25 3380, R25 10k. One of 2 NTCs is placed on the bottom of motor, another is glued on the top of ESC. MAVLink and temperatures are displayed on FrSky Taranis LCD using Lua scripts. There are 4 new telemetry screens: MAVLink formation with actual temperatures, MAVLink message, battery condition, temperature...Continue Reading
Posted by jociz | Aug 30, 2015 @ 02:49 PM | 10,451 Views
APM flight controller is powered with 5v that is generally provided by APM power management module. This module is regarded as a reliable step down 5v power supply and able to give around 2A at 5.3V.
But many experienced or observed that the Vcc of APM is prone to surge as it is loaded. In turn it may cause a brown out of atmel avr chip if it goes below 4.5v (typically 4.3v).

Mini APM Pro can be supplied by 2 voltage sources as I found out. One of them is the legacy apm power in and another is main out V+. Both of them are connected to the atmel avr Vcc power rail via own schottky diode. This is a good news for apm pro owner who wants to drive a servo connected to main out since it is enough to add a power source e.g. UBEC to the one of main outs. You do not have to bother the state of the jumper. The power rail of atmel avr Vcc is not loaded by any device put on main out.
I want to emphasis this is my experience and according to my measurement. So far I have not found any schematic drawing of mini apm pro.

I have added a UBEC to the main out. UBEC +5v is on the middle pin and negative is on the lower pin of S7. To diminish the load on atmel avr Vcc, I moved the 5V supply of telemetry radio to main out S8. By this, UBEC 5V is also powering the radio module.
The gain of additional ubec on main out is 2-fold:
- there are 2 x 5V sources supplying the atmel avr Vcc, minimizing the possibility of brown out
- telemetry radio directly powered by ubec instead of avr Vcc