Synergy E5S 626 UAV

My Synergy E5S 626 long range electric UAV helicopter has completed it's initial flight testing. It is flying custom firmware in a Pixhawk. Instead of using the common power modules for Pixhawk, which don't work all that well in high-voltage helicopters, I am using Castle Link Live telemetry to the RC radio for power system monitoring and logging.

On the first endurance test this helicopter flew for 28.5 minutes with 5% reserve carrying 1.35kg payload with two 3300 55C 12S batteries and a GoPro. On this test flight I had my channel 6 option set up to change the WPNAV speed to determine best efficiency cruise speed, which turned out to be be 15.5 m/s (~35 mph).

Minimum takeoff weight is 4,470g (9.8 lbs).
Maximum takeoff weight is 6,630g (14.6 lbs).
Useful payload is the difference, 2.16kg or 4.75 lbs, and can consist of hardware payload (cameras, towed loads, etc) and/or additional batteries. Maximum cruise efficiency, the way the power system and drivetrain is set up, is achieved at maximum payload where it cruises on 114.6 watts/kg. Cruise efficiency at minimum takeoff weight is 119.65 watts/kg.

On the full payload test with two 20C 5000 12S batteries it flew for 41 minutes @ 15m/s on a longer 1.6km test flight course. The 1.6km test course has level cruise flight sections, flying crosswind, upwind and downwind, with additional sections that vary altitude to measure performance in cruise climb and descent. It had a maximum tested range of 37km (23 miles) in that configuration, flying a combination of level cruise and climb/descent typical with following terrain elevation on autonomous ag survey flights.

The powertrain configuration is a Scorpion HKIII-4035-530Kv 3.4kW (4.4kW 5 sec), Castle Edge HV120 speed controller with governor, logging and telemetry, 9.971:1 main gear ratio, tail ratio 4.5:1, Rail 626 mains, Rail 96 tail blades. Equipped with Fubata HV servos operating at 5.8V, powered from a 20A CC BEC Pro.

Battery configurations, depending on flight time needs, can be:
1) Single 3300 12S (147Wh) providing 14 minutes cruise flight time with 3 minutes reserve
2) Single 5000 12S (222Wh) providing 21.5 minutes cruise flight time with 3 minutes reserve
3) Twin 3300 12S (294Wh) providing 25.5 minutes cruise flight time with 3 min reserve
4) Twin 5000 12S (444Wh) providing 38 minutes cruise flight time with 3 min reserve

These are maximum flight times - 10% allowance for wind on long flights is prudent.

CG is adjustable for all battery configurations. One battery is carried in the frame tray. The other in a belly rack. Note the helicopter has higher cruise flight power consumption with the twin battery configurations, despite the fact it is more power efficient. A typical MAPPIR/GoPro camera and mount is about .25kg, the rest of the payload is the extra battery capacity over the single 12S 3300 battery configuration.

Below is a video of the maiden test flight flown with the autopilot. About 2-3 hours of flight testing is required before attempting to fly a helicopter the first on full autopilot. Just like any full-size helicopter equipped with an autopilot, the SAS or Stability Augmentation System/attitude controller, must be properly tuned and configured so the Flight Director/navigation systems can issue the commands to the attitude controller to fly it. You will note the smoothness in which it makes coordinated turns on full autopilot - that does not happen by accident or "out of the box". While helicopters present somewhat of a challenge to set up as a UAV platform it is very hard for any fixed wing or multi-rotor type aircraft to match them for stability due to the quite high wing/disc loading a UAV helicopter flies at. This one is very close to the real thing, approaching a light utility helicopter in disc loading and performance. It has a maximum cruise speed of 37m/s (82 mph) @ 1,900 rpm headspeed, and Vne (due to Retreating Blade Stall) of 44m/s (98 mph). And it has the power to actually fly at those speeds in the twin 3300 battery configuration where there is enough battery capacity to get the full 3.4 kW (4.6 shaft horsepower) from the motor, with each 12S battery delivering 40 amps. This helicopter autorotates quite nicely at maximum takeoff weight, and a quite nice soft autorotation landing is easily doable from 75 feet AGL.

There is no current multi-rotor UAV platforms, even carrying massive amounts of battery capacity, that can come even close to keeping up with this thing in sustained cruise flight. A fixed wing can easily keep up to it, but a fixed-wing doesn't have the stability in the wind, nor VTOL capability. Making helicopters the ideal UAV platform for all the same reasons they are used for everything from air ambulance service to heavy lift applications in the world of full-size aircraft.



Wake up! Time to fly!
Nice work on this mate. You really have that dialed in nicely. I would think that is stable enough for S.A.R. duties with the way points and such. The extra payload available could go to higher resolution camera with a remote zoom function to enhance the visual capabilities. Could also work for police surveillance like on active shooter scenes where a real heli or live persons would be at risk.

Or it can and is a cool piece of kit for your hobby enjoyment. Are you going thru all this for a specific purpose or just because you can and it interests you?
I've been an ag pilot (I guess in some circles they still call us "crop dusters") for over 30 years. I use the autonomous helicopters for ag flights doing NIR imagery for NVDI analysis, crop insurance, crop scouting (RGB), watershed surveys, etc..

There is all sorts of uses including mining surveys an monitoring runoff on open pit mines, forestry, search and rescue and so on. The multi-rotor "drones" get all the attention these days because of marketing. But helicopters are more power efficient than multi's, have way more power and lifting capacity in the same size package, can cruise at way higher speeds, and are more economical to buy and fly at a particular performance level. The RC helicopter manufacturers have targeted their marketing to the 3D business primarily and have totally ignored what helicopters really excel at. Until recently, that is. Some of the heli manufacturers have started building UAV helicopters targeted to the high-end pros. Some examples are Velos Rotors' Velos UAV, Gaui's GX9, and one of the more recent examples is Thunder Tiger's CX-180