I’ve had an opportunity to take a look at the 9$ motors being sold by FPV Model – > RobotDog RD2206 2500kv.
What is so special with those motors? Price for sure. It is around £6-7 which is half price of the cheapest motors in UK shops.
Stator diameter: 22mm
Stator heigh: 5mm
Weight with long wires: 28g
At close look
RobotDog motors despite low price have (surprisingly) premium feel. Shaft is held by a C-clip. Material feels solid. Bell has thick cooling fins and coils are winded nicely. Motor feels smooth when spun by hand.
They come with 11cm length wires.
Magnets don’t have too much resistance and it would be fair to compare their resistance to Lumenier RX2206 2350kv which were my favourite smooth motors for a long time.
There is no vertical play in the bell at all.
I have tested motors on my 5” „Steele” Alien
KISS 32A Esc
KISS FC V2
ImmersionRC Tramp VTX
RunCam Swift V2
Crossfire Micro RX V2
Turnigy Graphene 4S 1300mah
After flight impressions
I flew over my usual flying spot – open space fields. Motors performed very well. They were very very smooth. There was no shakes or oscillations during the flight (I had some on the same setup with LeDrib motors for instance). Low end of the throttle had plenty power. On the other hand when punched (above 60% throttle) motors were not that much powerful. It comes down to the stator heigh and 5mm is not enough for motors to be very powerful. My flight was snappy enough but was lacking that extra kick you get with 7mm stator motors.
I had some bounce backs on that setup and that definitely needs tuning to get rid of.
I was getting almost 4 minutes of pretty snappy cruise and acro flying. When I pushed more throttle battery lasted me 2 minutes.
On average I have seen between 13-17amps and even 30 when punched.
My flight video:
Price! Only 9.99$ (£7.5) which is around half of what motors usually cost
Excellent build quality
Very smooth when spun by hand and in the air
Stator could have been taller to give more of top end speed
Mine came without the bolts for some reason
I didn’t know what to expect from motor as cheap as this but after the test flight I was positively surprised. Very smooth performance and great efficiency.
I can’t comment on durability at this stage though. Will update this post after more testing.
RobotDog motors can be recommended for those who want to build on budget as well as for new pilots just getting into the hobby. They are cheap enough to replace when needed. On the other hand I wish they could have been made with a taller stator and somehow low price or at least at similar level. That would make them even better choice.
I’ve built my first 7” mini quad few months ago. First flights were pretty rough when it comes to performance and fight times. Ever since I built it I tested numerous motors, props and battery combinations and finally found the good solution that gave me smooth footage. One of my colleagues – Kamil Bujniewicz (kbfpv – well known smooth freestyle pilot and absolute genius when it comes to PID tuning) commented my recent video recorded on 7incher „awesome and smooth as far as 7” prop can go goes”. His words mean business 🙂
In this write up I will explain the steps that I took to achieve the satisfying footage smoothness from 7” machine.
My initial 7” setup
InIn the past I was flying 6” Alien frame with 7” arms. It was just my modified favourite 6incher I used for about 2 years.
This machine was my first 7” experience. I’ve put TBS FPVision with Colibri FC on it + Crossfire micro RX. Motors of choice were ZMX X40 2608 1500kv prototypes I had around for testing.
Prop of choice was HQ 7×4.5 and HQ 7×4 because these two were the only ones available back then. First few test flights was pretty much bumpy ride and it didnt go well.
In the meantime my quad configuration changed few times. Nothing proved to work properly to be honest. There was always some oscillations but also weird yaw twitches I was getting.
I was never happy about how it flew, it seemed like a constant work in progress.
My current setup
After changing pretty much all bits apart from FPVision+Colibri+Crossfire I ended up with this:
Frame: ImpulseRC Reverb + 7” arms
Motors: ZMX X40 2608 1500kv
ESC: Spedix 35A blheli32 2-6S
FC: TBS Colibri Race v2 (hard mounted)
VTX: TBS FPVision
RX: TBS Crossfire
FPV Camera: RunCam Swift V2
Lipo: 5S between 1500 to 3000mah
Prop: Gemfan 7042 (for now)
Let me take you through the choice of components.
I have chosen Reverb because it was a little bit lighter than Alien but also it is very robust and stiff construction. Flex is kept to absolute minimum. Reverb has definitely lower profile than Alien but still plenty space inside and easy for upgrades. I have been using ImpulseRC frames for years and I am huge fan of their design work work.
I was lucky enough to be able to test X40 motors ever since they appeared on the market. Huge beasts @ 40g per motor. They are massive compared to typical 2207 motor. 26mm diameter and 8mm stator hight means business. Those motors deliver a lot of power even at low throttle. I also used some 2206 1400kv motors (TBS Endurance and BrotherHobby ones) for comparison but they were lacking power on my, rather heavy quad. This was not a case with X40s. I can’t back up my choice by any science but they just felt right on my quad and lack of power was the least of my concerns here.
Let’s face it, most current ESC on the market are very similar. I went with well priced Spedix. 35Amps seemed all right. Blheli32 is also very smooth, so my choice was simple. Good performers ? Hell yes. No need for a change.
Colibri wasn’t actually my choice but it came bundled with TBS FPVision. It is TBS own FC running F3. It integrates very well with power cube/FPVision, so I couldn’t choose anything else really. Solid performer despite F3 processor (old tech? nah…).
As a long term TBS Unify user I didnt change that. FPVision has Unify under the hood with add on of TBS integrated OSD etc. Great piece of kit. Current sensor comes calibrated out fo the box (yeah!) and it also allows for connecting external GPS to get flight info in OSD. Its my favourite piece of kit recently. Worth every penny.
This machine was meant to fly far so I could either choose FrSky R9 or Crossfire. I personally prefer Crossfire because its trusted and simply more reliable system. Choice was simple. Crossfire win here for me.
Camera doesn’t help with smooth footage but helps with how you see where you fly. I always used Runcams and Swift V2 is my choice and has been for a long time.
After using 4S and 5S on the same setup I came to a conclusion that 5S handles heavier quad better. I am getting around 8 minutes on 5S 1500mah and 13-15 on 3000mah. All depends of course how I fly. Those times are for fast cruise @ around 60-70km/h and around 10A current.
I have tried new Gemfans Flash 7042 after recommendation and looked no further. Those are twin blades (easier to carry), super quiet, almost like a stealth mode when flying around and give best footage. I may try different props and probably will, but for now gemfans blown me away. Can you imaging I am still on their first set and been for over 3-4 months now ? 🙂 I have never ever balanced those props. They even have few chips on them!
Tricks for smooth footage?
There is few things that made my quad flying smooth and improved the footage.
1./ ND filter
It’s not a secret that ND filter helps with jello on the flight cameras. It simply worked in my case too. I get very little jello in the footage. Because of my 3D printed GoPro mount I could only use stick on filter and I ordered few ND4 and ND8 from GetFPV. I use ND8 at the moment.
2./ Hard mount FC
It is hard to believe but that made the biggest difference actually. I can’t back it up with anything other than my flying experience, so don’t expect me to explain you why it made an improvement on my machine. I honestly don’t know. I’ve replaced soft mounts under the FPV vision with just nylon standoffs. No more weird yaw twitches and usual oscillations. All gone.
ButterFlight is known for a smooth performance it gives. I tried it as well and it made huge difference to my quad too. Pretty much stock PIDs, all filters OFF and adjusted rates. I have set 8K/4K and Q at 1400. That’s all. The feel is different compared to BetaFlight – pleasure to cruise.
4./ 48Khz PWM frequency
This setting made a difference in flying. In blheli32 suite I’ve changed it from 24Khz. Much smoother performance.
5./ Smooth fingers 🙂
That helps too. If you’re notoric jumpy racer or someone who change flight direction every half second you would never get a smooth lines. Patience is a key here. Don’t over compensate the quad, let it go, be gentle and just feel the flow. It helps. Maybe I am talking bullshit here, who knows. It works for me 🙂
When higher throttle is applied (above 50-60%) my quad still gets some oscillations. I set TPU at 0.4 but oscillations are still there. It doesn’t actually affects me that much because during my cruising I never go above 50% throttle to save some battery juice. Low end throttle on 7″ has plenty of speed too.
Jello is no more. I have tested my setup in cloudy and sunny conditions. Jell is not present there!
Also no more yaw twitch and any of the shakes I had in the past on 7″ props. Now it’s time to conquer some hills in Scottish Highlands this summer!
Video from the cloudy day:
Video from sunny day:
UPDATE Summer 2018Since the article was originally written I don’t actually own this particular 7″ Reverb any more.
I’ve had to downsize my quad fleet since I move onto wings recently.
I still have 7″ Cruiser but it’s is TBS Source Once with the following specs:
– BrotherHobby SpeedShield 2207.5 1750kv
– KISS FC V1
– KISS 32A ESC
– TBS FPVision
– TBS Crossfire
This machine flies even better smoother than my old Reverb.
Over the recent weeks I was testing two new NorthAero motors: Typhoon and Phoenix. Motors are designed by Sean Cox of NorthAero and manufactured by BrotherHobby.
In this article I will put down my thoughts about them.
Motors are packed in standalone boxes and have their specs printed on the label. Typhoon and Phoenix come with a set of four high quality M3x6 screws and a lock nut. They come with wires of approximately 17cm long which is very generous.
NorthAero motors are „bottomless” which means that there is less protection from the bottom but on the hand it is easier to keep the motor clean.
Design is all black with silver markings with cooling fins at the top of the bell. Shaft is held by a screw instead of C-clip.
2207.5 2650kv Typhoon
2207.5 2450kv Phoenix
Stator: 0.2mm Kawasaki silicon steel
Titanium Alloy hollow shaft
NSK 9x4x4 bearings
N52h arc magnets
16x16mm screw holes
34g of weight with long wires (around 31g with shorter wires)
Both Typhoon and Phoenix share the same specs apart from KV.
NorthAero motors are manufactured by well known BrotherHobby and their build quality doesn’t disappoint. Windings are neatly done and there is no vertical play in the shaft. Just another well made motor.
I was extensively testing both motors on my favourite freestyle quad:
Impulse Reverb frame
KISS V2 FC and KISS 32A ESCs
TBS Unify VTX
RunCam Swift V2 camera
I had very high hopes for this higher KV motor and I was not disappointed. Typhoons have a very smooth throttle response. There is a lot of torque at the lower and but when the punch is needed there is a very good top end here. I was blown away with the speed of those motors. Pretty insane.
As for battery life I was getting solid 3 minutes of flying on 4S 1300mah graphene lipo which is not bad at all. Lipo was a little bit warm at the end. I guess its because those are high KV motors that can actually squeeze every juice from the battery.
Little clip from on the first flights is here:
Lower KV option, should in theory give better efficiency and thats exactly what I noticed. Phoenix motors had loads of torque on lower end of the throttle but also top end wasn’t bad either. Lipo battery didnt sag as much as with typhoons and I had nearly extra minute of flight time making it 4 on my testing rig which. Of course, no two flights are the same but just take it an indiction.
/Flight video will be added later here/
NorthAero motors are pretty powerful. In fact, they are actually the most powerful motors I have personally tried so far.
On a negative side, they are little bit more expensive compared to competition. I have also managed to damage the shaft screw during bell removal. Somehow the thread disappeared and I couldn’t remove the screw.
Both Typhoon and Phoenix impressed me a lot. Excellent build quality and generally smooth performance is making them a very good choice.