• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

What is everyone's opinion of the new FT radial motor?

CapnBry

Active member
#81
I am a little confused on your results that the 8045 prop pulls the same RPM`s as the 9 inch prop?
You and me both. They're both "GWS Style Slowfly Propeller ____" from HobbyKing. One 8x4.5 and one 9x4.7. They're both supposed to be CCW (that's what my order says) but the 8x4.5 is actually CW. I reverse the motor direction and put the prop on facing the right direction so I dunno what else it could be. I also tried messing with all the knobs in BLHeli32 with timing, demag, rampup power, and PWM frequency to see if anything made a noticeable difference but I could only make the thrust numbers worse, especially in the case of rampup power.

I use the current (amps) measurement from the ESC telemetry and verify it measuring the voltage drop across the 50mOhm resistor inline with the power input. I'm not sure how you'd estimate it apart from using eCalc's PropCalc. For what it is worth, PropCalc says the 8" should run faster (9816RPM) and pull less current at max (8.9A). I've also tried with two different props from the same bag. All props are balanced before testing too.
 

DamoRC

Well-known member
Mentor
#82
I just received the C-pack version, 2218B 1080Kv and I'll run it on the thrust stand over the next couple of days. I don't have the Emax C pack equivalent to compare it to, but I do have a number of the NTM 2826 1200Kv motors, which were the original C-pack motor back in the day and I also have an NTM 2826 1000Kv which might be good to throw into the mix.
 

DamoRC

Well-known member
Mentor
#83
So I finally got started (and finished) with the testing of the FT Radial 2218 motor.

I used the thrust stand setup previously described here.

I am using an arduino hooked to a laptop to record data from various sensors.
Thrust was measured via a 10kg load cell and the HX711 chip. The thrust is zeroed and calibration checked between each run.
RPM is an IR LED / Diode beam break setup.
Voltage was measured for each cell connected through an appropriate voltage divider.
Current is measured using a Hall Effect sensor and the factory calibration. This agrees well with my HK wattmeter

For power, I used 3 x 2200mAh batteries in parallel (for both the 3S and 4S testing). There was some drop in voltage as the testing progressed but I don't think it impacts the results (or their interpretation) significantly. Please note that because of the paralleled batteries, there is less voltage sag than you would observe with one battery, which means that the motors can reach higher RPM, pull more current, and generate more thrust than you might see in an actual plane.

Each run involved ramping up to 25%, 50%, 75%, and 100% throttle and holding at each throttle level for a defined number of seconds (these runs are controlled automatically by the software).

Props tested ranged from 8 to 10 inch in diameter and 4 to 6 inches in pitch. For 4S testing I did not go as far as the 10 inch props. There is a mix of genuine APC props (9 x 6 and 10 x 6), not-quite-genuine APC props from HK (8 x 4, 8 x 6) and generic Slow Fly (SF) props (8 x 4.5, 9 x 4.7). I point this out because the prop type can make a big difference to the performance and even similar props can produce different results - my 9 x 6 APC prop performs differently than my 9 x 6 not-quite-genuine APC prop from HK. The only "standard" prop I am missing is the 10 x 4.7 which was a pity because a lot of these motors are tested on a 10 x 4.7.[Note: 10x4.7 data has been added]

I wanted to run a comparison against a similar motor. At one point early on in FT history they listed the NTM Propdrive 2826 1200Kv motor for use with their C-pack scale planes. I have a number of these on hand but they are not available anymore from HK. 2826 are the outer dimensions of the motor. I pulled the bell from an old one and confirmed that the stator is a 2211(22mm diameter, 11mm length) so probably not a great comparator for the 2218 FT Radial.

Given that there was some confusion as to the Kv of the FT Radial motor (the Item title in the store says its a 1080 Kv motor while the specs on the same page say its a 1180 Kv motor), I had planned to run the NTM Propdrive 2826 1000Kv motor also.

I measured the Kv of all three motors using the drill and AC voltage method. Basically, you spin the motor at a known RPM and measure the AC voltage generated between the phases and using some math, calculate the Kv. These are the results for the three motors.

Kv Measurement.jpg

Based on these data the correct number should be 1180Kv, so I limited the comparator testing to the 1200Kv version of the NTM.

After testing was complete, I plotted all the prop RPM and Thrust data together, regardless of number of cells or which motor was used. This was just a reality check to make sure I didn't have significant issues with any particular run ( a given RPM for a given prop should produce a given thrust regardless of the motor, number of cells, etc).

Thrust versus RPM for each Prop.jpg

You can see that all the curves are pretty smooth so there doesn't seem to be any testing problems between motors, props, or cells.

Below are the full set of testing data for the motors. I apologize that this data set is a bit dense. I am not going to interpret the data in any great detail, just to say the following:

(1) The FT Radial is a pretty powerful motor. Based on these results I am looking forward to installing it on my FT Edge and finally have some significant vertical power on 3S

(2) I did not see any significant increases in efficiency (grams/watt) for the FT Radial compared to the NTM - maybe the FT radial is a little better on 4S.

Is the FT Radial motor worth the higher price? That's a "How long is a piece of string?" question. You can pay a lot less and a lot more for similarly sized motors and typically, you get what you pay for in terms or performance and quality. So far, this feels like a quality product but time will tell. It doesn't feel quite as nice as the E-flite Ultimate 10 motors I have (these were donated to me), but then again, that's a $60 motor.

Technically the FT Radial 2218 it should be tested against a similar configuration motor. But even the Emax C-pack motor is a 2215 and not a 2218.
The closest I can find is a 2218 1100Kv motor on Bangood for $20, this is about the same price I paid for the NTM with prop adapter (except for the ones that went on sale in 2017 for $5 a piece and I picked up four of them).

Although I would love to buy a better comparator motor, I just don't need to spend more money on a motor for testing.

Anyway - here are the numbers.

Enjoy!

3S Testing

Update 030619 - Data for 10x4.7 SF props added. Note that the batteries used were not fully charged for this test.

3S Data Summary Updated.jpg

4S Testing

4S Data Summary.jpg
 
Last edited:

jpot1

Well-known member
#84
Wow, thx @DamoRC. Needed some more umph for my A-10 and this fits the bill. As a comparison I’ve got a C pack equivalent Turnigy d2836/8 1100kv and on 3s and a 10x4.5 it’s putting out 1000g. Jumping to this motor I should gain 300g! Nice.
 

JennyC6

Active member
#85
Looks like it really loves an 8x4SF on 4s and doesn't mind a 10x6 on 3S. Pretty nifty, I might actually grab a couple of them just to have in the parts bin for something! Would make a good lift fan motor for a hovercraft it seems.
 

DamoRC

Well-known member
Mentor
#86
Wow, thx @DamoRC. Needed some more umph for my A-10 and this fits the bill. As a comparison I’ve got a C pack equivalent Turnigy d2836/8 1100kv and on 3s and a 10x4.5 it’s putting out 1000g. Jumping to this motor I should gain 300g! Nice.
Your welcome. There's a prop test file associated with this motor (which is a 2217) on HK and it shows that if you set the timing to high you can get 1300g on 3S with a 10x4.5. Might be worth a try.

Here's the link.
 
Last edited:

DamoRC

Well-known member
Mentor
#87
Updated the 3S Table with 10 x 4.7 props. If thrust is what you need, then it seems that the 10 x 4.7 is the ideal prop for the Radial C Pack
 

PsyBorg

Wake up! Time to fly!
Mentor
#88
We need a sonic the hedgehog tapping his "I'm waiting" foot emote.

Kinda waiting on a mid to upper power 2306 2400 - 2600kv range quad motors to throw on the alien to really test the new design.

Rotor Riot motors are pretty poular but Im not a fan of open bottom motors. Closed bottom with a screw holding the bell not e clips would seriously make me happy.
 

CapnBry

Active member
#89
That's great work, @DamoRC! Your tables are even nicer than mine. I've been flying the 2212 size motor and had noticed some really low current readings in the blackbox logs so I set up my power pod and flight controller on the bench with the prop on, because danger is my middle name.

Running through the Omnibus F4 Pro V2 flight controller and a Flycolor Raptor F390 30A, my 9x4.7 prop maxed out at 10.1A (compared to on the test stand with a different ESC where I got 11.64A). This setup has a good 2x150mm of extra 18AWG wire compared to the thrust stand, but I don't think that would make 15% difference in current, and I'm hoping that doesn't mean there's 15% less thrust too. I've tried recalibrating the ESC, changing the timing, dither, and trying oneshot / 400Hz PWM and they all are the same. There's over 10W of power being lost somewhere in the setup, or the ESC is holding me back?

It is also interesting to note just how much the bigger props unload once they're moving through the air. 10.9A at takeoff becomes 9.13A at 20kph and my 10.1A from the above test becomes 8.26A at 45kph.
 

DamoRC

Well-known member
Mentor
#90
That's great work, @DamoRC! Your tables are even nicer than mine. I've been flying the 2212 size motor and had noticed some really low current readings in the blackbox logs so I set up my power pod and flight controller on the bench with the prop on, because danger is my middle name.

Running through the Omnibus F4 Pro V2 flight controller and a Flycolor Raptor F390 30A, my 9x4.7 prop maxed out at 10.1A (compared to on the test stand with a different ESC where I got 11.64A). This setup has a good 2x150mm of extra 18AWG wire compared to the thrust stand, but I don't think that would make 15% difference in current, and I'm hoping that doesn't mean there's 15% less thrust too. I've tried recalibrating the ESC, changing the timing, dither, and trying oneshot / 400Hz PWM and they all are the same. There's over 10W of power being lost somewhere in the setup, or the ESC is holding me back?

It is also interesting to note just how much the bigger props unload once they're moving through the air. 10.9A at takeoff becomes 9.13A at 20kph and my 10.1A from the above test becomes 8.26A at 45kph.
Thanks!

Probably the only way to know for sure is run the two ESCs back to back on the thrust stand.
 

CapnBry

Active member
#91
Probably the only way to know for sure is run the two ESCs back to back on the thrust stand.
Good idea, I'll probably do that next time I wreck this plane so I can desolder the ESC out of it.

I've also added a 10x4.5 prop to my test results on 3S above, you get 16% more thrust for just 37% more current! The sweet spot for performance vs efficiency on the 2212 seems to be at 9x4.7.
 

Kendalf

Well-known member
#93
I do have to say that the FT Radial's are built to take a beating! A few days ago my son and I took a Mini Scout up when the winds were way too strong. We dive bombed straight down into solid concrete at nearly full throttle from 30-40 feet up. The nose of the plane served as a great crumple zone but the prop cone took a hard enough impact to dent and deform the cone by nearly a mm. However, I spun up the motor and it seems to spin perfectly true still, without any noticeable wobbling of the shaft. So I'm certainly impressed with the durability of the FT Radial.
IMAG1505.jpg
 

buzzbomb

I know nothing!
#94
I do have to say that the FT Radial's are built to take a beating! A few days ago my son and I took a Mini Scout up when the winds were way too strong. We dive bombed straight down into solid concrete at nearly full throttle from 30-40 feet up. The nose of the plane served as a great crumple zone but the prop cone took a hard enough impact to dent and deform the cone by nearly a mm. However, I spun up the motor and it seems to spin perfectly true still, without any noticeable wobbling of the shaft. So I'm certainly impressed with the durability of the FT Radial.
View attachment 127043
THAT is a big-time ouchie! Granted the crumple-zones did their thing, I am still seriously impressed that the motor was not damaged.