From Multirotor Pilot Issue: 5
by Petr Hejl
DJI F550 is perhaps one of the most popular multirotor kits amongst multirotor hobbyists and enthusiasts. It is a well priced, easy to assemble kit with many available upgrades and accessories. A single-operator machine that is large enough to easily handle a GoPro with a 3-axis gimbal, yet small enough to be fl own in many places that may not be appropriate for larger, more expensive frames. It is still the machine I use the most in my aerial video endeavors.
After flying my F550s for a season, I began to feel that while DJI’s 2212 920Kv motors are a great start, I quickly started pushing their limits. Despite DJI’s recommendation to use 8×5 props with a 4S battery, I discovered that 10×3.5 props gave me more stability and the quicker reactions I was looking for. One downside of using these props with a 4S battery is that the 2212 motors heat up a bit, forcing me to keep an eye on the motor temperatures and take breaks between the flights to let the motors cool off . The glue holding the magnets inside of the 2212 motor seems to melt and loosen up in higher temperatures, which may cause the magnets to become loose and the motor to fail.
So, I set out to look for a suitable upgrade to my F550. There are quite a few upgrade options to choose from, with many people opting to extend or replace the entire arms to stretch the frame to 650- 680 size in order to fi t 12 to 14-inch props with appropriate motors. Aft er considering these options for a while I concluded that aft er replacing the arms, motors and ESCs, I would only have the center plate left of the original F550 kit and end up with rather large non-folding machine that’s difficult to transport. For an extra $140, I could have easily picked up a Tarot T680 Pro frame and ended up with a more practical machine (I did end up building one of these too, but that is a different story). I then sett led on fi nding the motors that will be a bit more powerful and can easily handle 10-inch props on a 4S batt ery without having to replace DJI’s 30A OPTO ESCs. Aft er looking at a few options, I sett led on T-Motor’s Navigator Series MN3110-15, 780Kv motors, combined with 10×3.3 Carbon Fiber T-Props.
Replacing the DJI stock motors was a breeze. The only necessary modification was shortening the motor wires and resoldering the 3mm male bullet connectors to make a clean install to the ESC’s under the arms. The motors’ bolt pattern matched the DJI arms with no problems, with the motors nicely filling the motor mounts. While at $39 for a pair the T-props are a quite an expensive proposition, they are known for their quality, which I can attest to. The fit and finish on them is simply perfect. I was even impressed by their packaging; each prop is wrapped in a velvet-like pouch with each pair in a box that reminded me of something that came from Apple. The props were almost perfectly balanced, I only had to correct the balance on one of them (balancing the props is important to get rid of any excess vibration on the frame and electronics, and to get rid of a “Jell-O effect” in the GoPro footage.
IN THE AIR
After the quick install and making sure the props were spinning the right way, it was time to test my new setup. Immediately aft er takeoff it was clear that the upgrade has completely transformed my 550. The copter was more responsive, nicely locked-in, really fast, and had no problems handling whatever I could throw at it. The biggest difference was in speed and ability to react much quicker to my commands. Since the carbon fiber T-props have no flex they give the machine a much more locked-in and nimble feel compared to DJI’s plastic props. Motor or ESC temperatures were no problem, even after a series of back-to-back flights on hot summer days. Even with 10×3.3 props, the efficiency with a 4S battery is still very good (see efficiency chart). There was no significant improvement in flight time (nor did I really expect one), I find 15- 16 minutes on an 8000mAh 35C 4S battery sufficient.
THE FINAL WORD
If you’re looking to upgrade your F550’s performance without having to re-build the entire machine and while keeping a relatively small frame size for easy transport, I can definitely recommend looking into this T-motor/T-prop combination, which will not leave you wishing for more. If you’re considering extending the arms to accommodate larger props, and also upgrading the ESCs, I would recommend looking into 650-680 foldable frames, such as Tarot T680 Pro, which are much easier to transport.