The DJI Snail Motor and ESC set have just been released by the drone giant, DJI. Popular for their aerial photography drones like the Phantom and Mavic, I’m interested to see what this motor and speed controller combination has to offer. I’m expecting very good things, as the Drones produced by DJI are of the highest quality.
Looking at the motors themselves, these are 2305 Motors weighing in at a very nice 27.8 grams. Combined with the 5048S tri blade props from DJI, the Motors are claimed to be capable of producing 1.32 kgs of thrust. The Motors are an interesting size, having a larger than normal stator width of 23mm compared with the incredibly popular 22mm and a standard 5mm stator height. The 22mm stator has become the standard for racing right now, as it offers a good blend of power, torque and weight.
Increasing the stator diameter or height typically increases the motor weight because it is simply bigger, but DJI seem to have been able to increase the stator width without producing a heavy motor. Maintaining the standard 5mm stator height is impressive with the larger diameter, so it will be interesting to see whether the light weight is provided by a sacrifice in durability. Only time will tell!
The larger than normal stator width means that the motors will be excellent with the low down torque. The standard stator height makes the motors capable of still being able to provide mid-high speed torque. As well as the standard 5048S, I would expect these Motors to perform very well with 6 inch props and possibly even with six inch tri blade props with a low pitch. These type of props need a lot more torque low down in the RPM range because of the large amount of thrust produced. Where these Motors aren’t expected to do so well is on the ultra high kV applications with lower pitch props, because the wide stator isn’t particularly suited for high kV applications. These typically require a taller stator.
The motors are currently available in 2,400 kV, which is a nice mid-point in terms of the current racing motors available. Most popular motors currently come in 2,300 and 2,600 kV variants and it would be nice to see DJI offering some alternative options for the Snail range. This would allow users to choose a motor more specifically for their needs, where the 2,400 kV option isn’t going to excel at any one thing. I would like to see a lower, possibly 2,000 kV option for acrobatic flying and a higher 2,600 kV (or higher) option for those hardcore racers missing out on the top end speed.
The speed controllers that come with the Motors have an impressive specification, providing 30 amp continuous current as well as a 45 amp burst current. I would only size based on the 30A rating, as the burst current is only rated for 3s. This is unusual, as burst current ratings are normally based on a 10s duration. I feel this is somewhat deceptive and would imagine that the real (10s) burst rating is likely closer to 35A.
Unfortunately for those wanting to use 5S or 6S with these Motors and speed controllers, both components are only 4S capable. Since these have been targeted at racers, this seems a bit of an odd move by DJI, who must surely be aware of the growing trend towards these higher voltage battery options. More and more of the popular pilots on YouTube have been modifying their electronics, so that they are capable of flying 5S and 6S battery packs. The extra speed these higher voltages offer means that the Snail system could very quickly find itself left behind in the rapid drone technology development race.
DJI has marketed the ESCs as rapid response, capable of handling changing inputs better and providing a more agile, responsive flight experience. If this is true, it will be fantastic for racers, where every ms response time can be the difference between a podium and a nasty crash! DJI claims that the ESCs come with “unique race optimised control algorithms” improving the efficiency and response. If this enables longer flight times, even by a small percentage, it will be a real improvement over the current technology.
When flying freestyle this isn’t a particularly big issue, but if you have ever been to a race you may have encountered the problem of having to drain your batteries almost completely just to finish. It’s nice to see that the ESCs also provide Oneshot125 support and they can be programmed using the ESC Programmer and DJI Assistant 2.
A great addition to what could have been a fairly standard system is the inclusion of the new quick-release propeller system. The ability to quickly swap out propellers without tools is a really interesting feature. If you prefer to use standard props, a Snail propeller adapter is available, which allows you to use the more standard prop mounting.
The DJI Snail propulsion system is available with a range of new props from DJI, including twin and tri bladed 5 inch props, as well as 6” and 7” standard/twin bladed props. The tri bladed 5” props have been made specifically for fast forward flight and DJI describes them as “optimized for forward flight and in addition to larger thrust, it creates less drag and uses less power when flying forwards”.
These will be interesting to test out, as until now the majority of props are rated on their static/bench tests, rather than real-world flying conditions. The 6” props are recommended for more entry-level drone racing and can be twinned with a 3S battery instead of the normal 4S. Similarly, there are also 7” 3S props available, more suited to aerial photography. Both the 6” and 7” props claim significantly extended flight times, but no numbers are available just yet.
The final interesting addition to the prop line up, is the inclusion of a 6” 3D prop! This makes inverted FPV flight possible once the ESCs are set to 3D mode.
DJI Snail Pros
- Price – Under $100 for all 4 motors and ESCs is incredibly cheap
- Large thrust from a lightweight motor, will be competitive when racing and interesting for freestyle flight
- Range of prop options available
- Quick-release propeller system is great for getting back in the air quickly after a crash
DJI Snail Cons
- Not tried and tested yet, so durability is unknown
- Lack of 5S and 6S capability
- Extras like the ESC programmer and adapters for standard props are all additional extras and not included in the standard package
This is an incredibly attractively priced package and you will find it very difficult to find equivalent performance for the price on offer. Where the system is let down is by its lack of track record. Once the kit has been in use and has been crash tested by real world pilots under normal usage circumstances, the kit will be very easy to recommend. For now, we think it is a great option and on paper at least, will be providing the current more expensive options some serious competition.