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Introducing the new 100 KM long range Mapping / Video conservationdrones base on Skywalker air frame. With the new power system, the flight duration is more than 3 hours and range over 120 KM with 200 grams payload, typical weight for point and shoot camera such as Canon S 100 GPS on board. The all up weight of the drone is 2.9 KG ready to fly.

About 18 months ago, I've achieved 100 KM with FX 79. But it has never put into practical use in the field. The main reason is with the required batteries on board, if I put payload , such as camera in front, I'll need to add weight at the rear end to get the plane balance. The total weight will be about 3.7 KG and hand launch become very difficult and dangerous. landing a heavy plane at confine area is another challenge. 

I have tried a few combination but non of them meet my requirement until I found the current power system. The major breakthrough is the new Lithium Ion battery pack which rated at 3 C continuous discharge. According to supplier, it use imported LG Lithium Ion battery and the pack is assemble at their partner factory at China. 

The air frame I use is the proven Skywalker 2014 1800 mm three piece wings model. I think other version of Skywalker should give similar performance. The motor is SunnySky 2820 800 kv match with APC 12 x 8 electric propeller. With this set up, you'll need to limit the top end power via Mission Planner to limit the full throttle at about 26 Amps, which give more than enough power for take off and climb to altitude. Once enter cruising mode, the average amps draw is only about 5 to 8 Amps.

The 100 KM attempt took place at my local flying field. It was a sunny Sunday afternoon with some winds. Load the fully charge 4S 21000 mah Lithium Ion battery and some basic set up, it was ready to go. Because of the light weight ( 2.9 KG ) of the plane, I was able to hand launch it with my left hand while using my right hand to hold the radio transmitter. Take off was effortless and after climb to about 60 meter, I switch to RTL mode to test the auto pilot and climb to mission altitude ( 100 meter ). Once everything seems fine I switch to Auto and start the mission.

Three hours and 5 minutes later, It has travelled 117 KM with 29 % battery capacity remaining. As it was getting dark and it actually completed the planned mission, I decited to land. If there was enough time, when push to the limit, I think it can travel another 25 to 30 KM or 40 to 50 minutes. But for general mission flying, it is always good to have about 25 % of reserve capacity for better battery life cycle and prepare for unfavourable weather condition. Another issue need to consider is camera battery life. Most camera will not operate for more than 2 hours without extenal power supply.

The lithium ion battery I used can charge with normal Lipo charger at 1 C rate, but the discharge curve and minimum voltage is difference from Lipo battery that we all familiar with. When high power was loaded, such as take off, the voltage will drop significantly. In my case, the freshly charged battery voltage reading is 16.97 volt. During take off at full power, which draw 25 Amps, the voltage drop to 15.6 volt but once enter cruising mode, it bounce back to 16.4 volt or so. For air plane, it is safe to discharge down to 3 volt per cell or 12 V for 4S pack. If you push to the limit, It can hold up well until 2.8 volt per cell, after which, the voltage will drop fast. You will need to change the low voltage cut setting of your ESC to LOW or change the battery type to NICD/NIMH to avoid premature power cut off by the ESC.

Unlike lithium polymer battery, once the Lithium Ion battery discharge to very low voltage, say 2.4 volt per cell, it can bounce back to about 3 volt if you cut off the power for a while. If you are flying FPV and fight for the last KM to reach home, this technique and the characteristic of lithium ion battery may save your day or at least get it closer to you.

With 100 KM range, the new long range conservationdrone open up the posibility to map or video area that is previously unreachable by normal drones due to unaccessable suitable take off / landing area. It will also suitable to long range river bank ripirian area monitoring or border patrol or any other mission that require long range flight and long flight duration. Flying at 300 meter, it can also map 1500 Ha at about 10 cm per pixel resolution, which make large area mapping possible with a single flight. The camera will need external power.

Below is the specification and parts components for the 100 KM Skywalker conservationdrones. Any experience drone builder can build it with the available information. 

Air frame : Skywalker 2014 1800mm 3 piece wings
Auto pilot : HK Pilot Mega 2.7 master set
Radio control : Futaba T 8 J
Telemetry : HK Pilot 915 air. RFD 900 ground
Motor : SunnySky 2820 800 kv
Servo : Hitec 65 HB
Propeller : APC 12 x 8 Electric
Battery : 4S6P 21000 mah Lithium Ion
On board sensor : Canon S 100 GPS

Here is the link for the tlog of the 117 KM flight. From the tlog, you can view the complete flight mission as well as extract parameter from it. Use it at your own risk as some setting may be difference from user to user. 

https://drive.google.com/file/d/0BwRKGgIOJSELcnp0djliZGs4NkU/view?usp=sharing

Here is the KMZ file 

2016-01-10%2015-15-00.tlog.kmz