After being very happy flying the ARACE GriffinPro 1 for well over a year, I was delighted when ARACE offered me one of their new Angel 3 quadcopters.The Angel really is special, with an extraordinarily long flight time for an electric multicopter of this size.Without payload, the Angel can reportedly achieve 139 minutes of flight time, which is several times longer than is typical. This allows you to cover a lot of ground. These long flight times have been achieved while still having very crisp and confidence-inspiring control.The Angel comes in a neat foam carry case, and the frame folds up extremely easily with spring loaded catches to lock the legs and arms in place for flight with no need for any tools. The carry case also holds the transmitter which provides access to QGC as a GCS, plus a live feed from the digital FPV camera at the front of the copter. You can have the copter ready to fly in well under a minute.For the project I am working on with the local fire services we have integrated a SIYI ZT30 thermal camera which attaches over ethernet to the inbuilt IP radio system of the Angel. ARACE kindly provided us with longer legs for the Angel so the camera has enough clearance from the ground for takeoff/landing.For my setup, I have taken advantage of the ethernet tethering capability of the hand controller to allow me to connect my laptop for using MAVProxy and other custom GCS tools for the SIYI thermal camera. I get a wide angle, zoom and thermal video streams from the gimbal, while also getting the FPV video feed from the built-in camera of the Angel.CAN and BDShotThe Angel is based around the MatekH743 flight controller, so it has plenty of CPU power for things like lua scripts and complex missions. It is the more recent varient of the MatekH743 which has two ICM42688 IMUs, which is a good choice.Despite the small size and emphasis on low weight, it has dual DroneCAN uBlox M10 GPS modules with good antennas.Control of the ESCs is via bdshot, allowing ArduPilot access to high-rate RPM data, which allows for good notch filtering, allowing for a high-quality tune.Battery MonitoringThe Angel uses a new capability in the ArduPilot AP_Periph system to have a balance plug DroneCAN node, allowing the Angel to perform a pre-arm check that the balance between the 6 cells of the battery is good. This helps ensure the battery is in good condition, which is important if you are planning to take advantage of the long flight times.As expected from ARACE, which takes pride in attention to detail, the batteries come pre-fitted with anti-spark connectors, and fit perfectly in the battery bay, with the balance lead slotting neatly into the DroneCAN balance plug adapter.The battery itself is a 6S 2.5kg 35Ah solid state LiIon, which is a key reason why the Angel is able to get such a long flight time (along with the very lightweight but sturdy build).The copter itself weighs just under 1.7kg, so with the SIYI ZT30 I’ve been flying at around 5.3kg. I’m getting a current draw of around 20A in auto missions at 600m above sea level.Tuning and Wind EstimationThe tune on the angel is top-notch right out of the box. ARACE has put in the extra effort to calibrate the drag coefficients on the copter, allowing it to provide better height estimates when in forward flight (compensating for aerodynamic effects) and also allowing it to estimate wind speed and direction. This is a real testament to the effort ARACE has put in, as while anyone can calibrate the drag estimates and setup an ArduPilot-based copter with wind estimation, very few vendors actually do that (in fact this is the first copter I’ve seen where the vendor has done this in the factory shipped configuration).To go along with this wind estimation calibration ARACE has pre-installed lua scripts for automatic estimation of the time it will take to get home, taking into account the measured wind. That allows you to confidently fly the Angel over much longer distances than most copters.ConclusionIn summary, the ARACE Angel is a truly excellent small quad, backed by a vendor who takes customer support seriously. I’m delighted to have one and look forward to a lot of good flights as part of the bushfire research project I am involved with.Congratulations to ARACE on a great design!
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