There is very little community information available on sub 250g Quadcopter propulsion systems, and choosing the correct motor/propeller (and corresponding battery that can keep up) can make or break a build. I've decided to put a considerable amount of my free time into testing, gathering detailed metrics, and reporting on different motor and propeller combinations. I've started testing with 3" class quads, but will venture into 3.5", 2", 4" and eventually see if I can find suitable motors and propellers for sub 250g 5" builds. So far my testing has tremendously helped me make my quads fly better, and I'd like to help others do the same. I invite you to join me in discussing these tests, what you'd love to see tested, and assist with analyzing the results.

Test Methodology

I've built code to fully automate each test, so that the results would be the exact same (as close as practically possible) if I run the same test over and over again. In addition to the automation, in order to achieve my goal I had to eliminate major variables common to motor testing. These variables are input voltage, and heat. When most people run these types of tests, they power the motor with a fully charged lipo, and slowly ramp up the propeller from 0 to 100% throttle, gathering data. The problem with this methodology is that their is no practical way to ensure the voltage is the same for each throttle position between tests, due to the dynamic (based on remaining capacity) sag of the voltage from the lipo. As the motor spins up it generates heat, which adds resistance, significantly impacting performance. With smaller motors, heat becomes even more important, because they can heat up extremely quickly during static thrust tests. To eliminate the voltage sag, I power the thrust stand with bench power supplies, calibrated to the correct voltage (within 0.01v), which maintains a constant voltage regardless of load. The only voltage sag is from the wire to the stand (same size for each test), and the motor itself. Heat is eliminated as the automation bursts the motor to the correct throttle point being tested, in increments of 3% for the entire throttle range being tested. Between these tests, the motors are idled long enough for them to cool off (verified using a thermal camera). Before these variables were eliminated the tests results were extremely inconsistent, but are now extremely repeatable.

I made a video that goes into the methodology in more detail here:


If you prefer to read more about it instead of the video, I wrote a fairly detailed article for Tyto Robotics where you can learn about the methodology, and what problems I'm solving by doing it this way: https://www.tytorobotics.com/blogs/custo...ethodology

Feel free to ask any questions.

Results

Once the testing is conducted, all of the results are compiled into a CSV/spreadsheet which has statistics for each throttle position tested. These statistics include grams of thrust, voltage, current, measured motor RPM, watts, and grams of force per watt. I take this data and build charts to help visualize the data, and formulate my own observations, conclusions, and at times, come up with even more questions that require further testing.

Completed

• Initial 3" Propeller Tests (8 Propellers)
  
• Initial 3" Motor Tests (5 Motors)
  
• 3.5" vs 3" Propeller Tests on 1404 sized motors
  
• 3.5" vs 3" Propeller Throttle Response Tests
  
• 4" Propellers on 1404 3800Kv Motors
  
• 4" Gemfan Floppy Proppy Critical Failure on 1408
  
• 1404 vs 1408 using 3.5" Propellers
  
• 1404 vs 1408 at 3800Kv on 4" Propellers
  
• 3.5" HQPRop T3.5x2x3 vs HQProp T3.5x2.5x3
  
• 2 Blade HQ Prop T3.5x2.2x2 vs 3 Blade HQProp T3.5x2.5x3
  
• 4" Propellers on 1408 2800Kv Propellers (with build analysis against 3.5" builds)
  
• 5" Propellers and Motors on 2004 sized motors (with build analysis against 3.5" builds)
  
  

Builds based on test results

• 3.5" build using top tested components to demonstrate capabilities.
  

Currently Working on

• Mid-Size 3.5"-4" motor testing
  
• Whoop motor testing (thrust stand redesign/viability testing)
  

Give me a bit while I make a few posts with the results I have. I'm moving it over from somewhere else.

I've completed testing on 5 different motors capable of driving a reasonable aggressive 3" propeller (also some 3.5/4" in later testing). The propeller used to test all of the motors was a HQProp T3x3x3-PC (3 blade, 3 inch pitch propeller). All testing was done at a regulated 16.0v driven by the same BLHeli-32 ESC.

The purpose of this test was to compare each motor directly against one and other to be able to see the difference in performance and efficiency.

The motors tested:
- Flywoo NIN 1404 V2 3750kv
- iFlight Xing X1404 3800kv
- T-Motor F1404 3800kv
- E-max 1306B v2 4000kv
- BrotherHobby VY 1504.5 3950kv

Here is a video outlining the testing, results, with analysis of the results:


Here are some quick reference graphs from the results. The forum makes them a bit small, so click on them or drag to a new window to see the larger version.

Grams of Thrust by Motor Utilization


Efficiency by Motor Utilization


Grams of Thrust to Watts of Power


Exact Motor Weight

I've completed testing 8 different 3" t-mount propellers with a sample set from various vendors and pitches to get started. These were conducted on an Emax 1306B 4000kv motor, a BLHeli-32 ESC, at 16.0v (4s).

The propellers tested were:

• Gemfan 3035BN-PC
  
• Emax Avan 3x2.4x3
  
• Gemfan Hurricane 3018-2
  
• Gemfan Hurricane 3016-3
  
• HQProp T3X2X2-PC
  
• HQProp T3X3X2-PC
  
• HQProp T3x1.8x3-PC
  
• HQProp T3X3X3-PC
  

Here is a video outlining the testing, results, with analysis of the results:




Here are some quick reference charts from the results. The forum makes them a bit small, so click on them or drag to a new window to see the larger version.

Thrust by Motor Utilization


Efficiency by Motor Utilization


Grams of Thrust to Watts of Power


Exact Propeller Weight

The goal these tests and analysis was is to determine if 3.5" propellers can and should be used on 3" hardware (1404 motors), without having to add additional weight. I tested 3 different 3.5" propellers against one and other, and also against performant and efficient 3" propellers.

The propellers tested:
3.5"

• Gemfan Hurricane 3520-3
  
• Emax Avan Scimitar 3.5x2.8x3
  
• HQProp T3.5x2x3-PC
  

3"

• Gemfan 3035BN-PC
  
• HQProp T3x3x3-PC
  

Here is the video outlining the testing, results, with analysis of the results: 



Here are some quick reference charts from the results. The forum makes them a bit small, so click on them or drag to a new window to see the larger version.

Thrust by Motor Utilization


Efficiency by Motor Utilization


Grams of Thrust to Watts of Power


Exact Propeller Weight

Before this test I updated the testing methodology from previous tests (above this post).

Quick summary of changes:

• Made wires to the thrust stand thicker and shorter to decrease line voltage drop at higher currents.
  
• Added 10A more current potential.
  
• Increased max throttle tested from 90% to 95%
  
• Increased samples per second and changed idle position to allow me to capture the throttle response more accurately. This will now let me to reasonably show throttle change response times between test subjects. This also let me lower the hold time for each test since more samples are captured per second (4+ times more)
  
• Increased testing resolution (throttle points tested) from every 3% to every 0.5%.
  

Now that I can capture, measure, and compare RPM spin up data, I've redone the 3" vs 3.5" propeller testing to capture and analyze this, which I thought was fairly important when comparing larger propellers on the same motor.

You can see the analysis here:


Key data:

5% to 90% motor spin up response time

In this test set directly compared the performance, efficiency, and response of 4" propellers on 1404 sized motors against each other, and 3"/3.5" propellers.

You can see the full analysis here:


The Motors tested:

• T-Motor F1404 3800kV
  

The propellers used in this test set:

• HQProp T4x2.5x2-PC
  
• Gemfan Hurricane 4024-2
  
• Gemfan Hurricane 4023-3
  
• Gemfan Floppy Proppy F4019-2
  
• Gemfan Floppy Proppy F4019-3
  
• HQProp T3.5x2x3-PC
  
• HQProp T3x3x3-PC
  

Reference Charts


Thrust by Motor Utilization


 
Efficiency by Motor Utilization

 
Grams of Thrust to Watts of Power


Exact Motor Weight


Tip Speed by Motor Utilization

When doing 4" tests on 1408 motors, I had Gemfan Floppy proppy propellers explode on me at high RPMs. I repeated the failure on camera and documented where it happens.

This test set/analytics directly compared the performance, efficiency, and response of 1404 sized motors against 1408 sized motors on 3.5" propellers.


Here is the video outlining the testing, results, with analysis of the results:


The Motors tested in this test:

• T-Motor F1404 3800kV
  
• T-Motor F1408 3950kV
  

The propellers used in this test:

• Gemfan Hurricane 3520-3
  
• Emax Avan Scimitar 3.5x2.8x3
  
• HQProp T3.5x2x3-PC
  

Reference Charts

Thrust by Motor Utilization
 

Efficiency by Motor Utilization
 

Grams of Thrust to Watts of Power
 

Exact Motor Weight

 
Tip Speed by Motor Utilization



Spin up response from 5% to 95% throttle



Motor Response from idle to 36,000 RPM

In this test l directly compared the performance, efficiency, and response of 1404 sized motors against 1408 sized motors on 4" propellers at 3800Kv.

Here is the video outlining the testing, results, with analysis of the results:


The Motors tested in this test set:

• T-Motor F1404 3800kV
  
• T-Motor F1408 3950kV
  

The propellers used in this test set:

• HQProp T4x2.5x2-PC
  
• Gemfan Hurricane 4024-2
  
• Gemfan Hurricane 4023-3
  
• HQProp T3.5x2x3-PC
  

Reference charts (most relevant)

Thrust by Motor Utilization


Efficiency by Motor Utilization


Grams of Thrust to Watts of Power


Tip Speed by Motor Utilization


Idle to 90% Spin up Response

I put that data from 3" and 3.5" testing into practice and made a DJI HD build that has a amazing performance, efficiency, and a high thrust to weight ratio with reasonable battery sag and flight times. I made a video goes over that build, the data behind it, performance expectations, and basic flight test data. The result is my new favorite quad. The thing is stupid fast, agile, and just really fun to fly. 

Part 1:


Part 2:

Alright that should be all of the data posted. I'd be happy to answer any questions. Feel free to make posts in this thread and have an actual discussion/theorycrafting. I'm linking individual test posts in the OP to help people navigate through the thread.

I'll post results future results as they are completed.

As a teaser here are some 5" props to be tested on a 2004 motor.



Edit: Well Crap. I just noticed I posted this into the HD FPV sub forum instead of the Motor, Esc, and Prop sub forum. If someone could get a moderator to move this there, that'd be great because my brain is already numb from posting all this once :F

Awesome work. There is a lot to absorb here.

I think the biggest limitation or concern is test equipment. As long as these tests are performed in the same lab using the same equipment, they could be used as performance bench marks.

How are those Korad's working for you? I saw them several years ago and almost bought one but then EEVblog forums just made me nervous. You know what I mean the power ON spikes and the ripples etc etc.

What's your opinion on the motor thrust stand? Always wanted one but I think I will not have much use out of it since I dont get to test lots of equipment such as motors or props.

By the way, I would suggest this Thread was better in the Motor/ESC and nothing related to HD FPV systems.

Look at my last comment lol. I've reported my own post to hopefully get a mod to move it.

The way I'm doing the testing seems to be fairly accurate for comparative bench-marking, and I've gone as far as I can to practically remove as many variables that I can think of. I've gone through a few iterations of automation code that I was never happy enough to publish data over before it matured to this point. I've run the test sequences over and over and there results are near identical each time plus or minus a a small number of grams/milliamps. Most importantly, when I implement the results into a flight (i.e. trying poorly performing or better performing props), the experience seems to match.

The Korads are absolutely fantastic power supplies. I've had a bunch of other power supplies (including a 60A chonker), but these are great in terms of control and performance where if I set them to output at 16.00v, that's what they'll give even near max current. Not sure about power on spikes, but turning the output on and off has zero issues. The output voltage on the scope is extremely flat, even when a motor is spinning up (that is in the top picture of this thread). The 10A Korads have a serious design flaw though (at least for how I use it). The cooling fan is based on the output current, so it'll spin up faster or slower depending on the current it is providing. In theory this sounds great because overall they will be quieter, but for the testing I was doing they actually started to overheat and disable the output (safety feature) because the automation bursts to high current for a few seconds, then back to low over and over again where the fan on time wasn't enough to remove the heat. I rewired the fan to be on 100% all the time and they've been absolutely perfect since. When I'm not doing testing I use them for everything including charging lipos or powering my soldering iron at the highest voltage. More people should own one for the hobby, because they are much better than a smoke stopper as you can set the current limit to the milliamp, and when testing a quad you can set the current to just what it needs so if you do have props on it wouldn't be able to harm you since if the motors spun up it would just kill the voltage until the flight controller resets.

The thrust stand has been great for the price. Any limitations it does have (i.e. 5hz thrust sampling) I've worked around with code. The people that make it is a small company in Quebec, and they've been amazing to deal with. They replaced the control board when the thrust sensor smoked out randomly well after the warranty expired.