That's a bold statement ... Worlds Best. But it's even larger than that. Not just Worlds Best, but best for most all applications less than 30 Amps (limit of the tests). That means:

- duration ships that only pull 2 to 8 amps per rotor

- most all 6S and smaller ships (exception of nano-ships)

- any-size FPV racer

- any other ship in between

Why almost any size? Shouldn't a small FPV racer use a smaller and lighter ESC for response? Yes, if it does better on a net-lift response test. In other words, when you penalize the ESC for it's weight, is it still better and faster? What i continue to see is ESC manufacturers downsizing critical components of the ESC at a net loss. They weight savings is lost because of greater thrust loss and response. In other words, this heavier ESC will out accelerate, in the real world, a smaller and lighter ESC.

Why post this? To move technology forward, we need to report to industry what works and what doesn't. For some reason (i don't know why), this ESC works better than all others tested:

- for generating maximum thrust from the motor***

- for net-lift efficiency or the grams of weight it can lift (after it lifts the rotor) per watt

- for response (how fast it can generate targeted lift)

These tests were conducted on multiple days on multiple rotors of highly variant size, always being immediately compared back to another DYS 40A multicopter test to ensure that the baseline wasn't changing.

The ESC that dominated is a DYS 40A OPTO Multicopter using SimonK. The photo is included because there are two others that carry a similar or same name.

- Not the white cover DYS BLHeli 40A

- Not the one that is says "Programmable" versus "Multicopter" in the blue/purple band across the front

Have i tested all ESCs? No, but if you are convinced you know of one that would work better, let me know. I've tested most all of the following and one or more of their variants:


- Multistar

- Turnigy

- T-Motor

- Afro

- Motortron

- Quattro

- 3DR

- Spider



- Aris


- AutoQuad

- Exceed

- HobbyWing

- Lumenier

To do a test like this, a highly repeatable and finite test stand is needed. It took a while to develop one but what works is one that:

- measures (at a minimum) volts, amps, thrust, motor temp (shoots IR up the aft end of the motor)

- eliminates harmonics between the rotor and load sensor (this proved difficult but achievable)

- is calibrated and proves repeatable within 1.5%

- controlled by a system that can precisely repeat a rotor test (uses a Audurino Mega)

- directly feeds the data into Excel for analysis (uses DATAQ)

- uses a test script that produces repeatable results

- uses a test procedure that minimizes repeatability error (used average of multiple tests)

How much better is this ESC?  On average:

- 4.4% higher net lift (after it lifts itself)

- 2.3% more net-lift efficient (usually the larger the better)

- from more than twice the response or the same response as other ESCs (usually the larger the better)

                                                       So how to make it better?

Step 1: Strip it naked. See photo below.

           ... remove the cover

           ... remove the heat plate (better to locate the ESC under prop wash to run cooler, see below)

Step 2: Right-Size the bullet connectors or wires (see above where heavy wires are replaced by 2mm bullets)

           ... remove the large bullet connectors or wires

           ... replace them with ones that are the most net-lift efficient (where heat loss = weight loss)

Step 3: Seal the ESC. Seal it with Electrical Sealant to protect from moisture and conductive dust

           ... tape or plug connectors and wires

           ... repeatedly spray each side from different angles

           ... a mistake i made was not sealing the bullet connectors and solder

               - don't tape them off like i did

               - insert a male connector into the end of bullets so sealant doesn't get inside them

Step 4: Locate ESCs under Prop Wash. See photos below. The turbulence generated by the prop does not adversely affect lift when the ESC is placed on edge to the prop wash.

           ... Use something non-conductive like hot glue to bond the ESCs to the motor mast or spar

           ... Face the FETS (the little square warehouses or Fire Emitting Transistors) to open air

           ... Protect the ESCs from below from ground contact (not needed here because of clearance)

back-side with hot glue

front-side with FETs completely exposed to open prop wash

Step 5: Tie up wiring. Use dental floss to secure wiring away from the prop.

***Note: The T-motor Air 40 in high-timing mode (an option) generated higher thrust, but at the sacrifice of efficiency and motor temp. Also, the T-Motor Air 40 was 2nd best and close in performance. If you are using an Air40, it probably isn't worth switching.

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Thx Emin! I forgot about this. Excellent link.

Good point Paul!

There is a racing car and there is an off-road car... or even a truck... and then is a tiny Smart. So there is no universal car (read ESC :-).

Dorjano - Since you are DB not DJ, ask yourself the following two questions. Is the Al block large enough to absorb all the heat transferred from the ESC in a 10 minute flight? If your answer is no, then ask, where does it go and what is the specific heat of that media? Once you understand that, then please edit your statement above.

You ask two good questions.

1) Herkules ESC -I was about to buy the Herkules 4-in-one when i saw the cost ... thought i''d wait until someone sent me one (other 4-in-ones have not tested well) ... i'd do a non-destructive test and send it back. so it might be a great ESC. also please understand that there is only a 5% or less difference in most ESCs. We are talking about getting all ESCs to their very best. This can be only done by rigorous testing, admitting to and fixing non-optimal aspects of design, and focusing first on fundamentals.

2) Wire Size - Why would wire sizing be different for an ESC (or motor) than what industry has adopted as rules of thumb for all ground-located electronics? I will let you answer that question because i believe in you. My only hint is this. If we operated on a rule of thumb that we tolerated almost no heat loss, then wire size would be 20 mm and the ship might not get off the ground even while running at full power and 3x the amps. If wire size was 26 AWG, heat might not "run-away" but there would certainly be a huge loss in watts (heat), even though the ship was flying at less amps (when measured at the motors versus at the battery; in between there is a lot of heat loss). Please explain.

Thanks you. I've also tried about a 10 to 15 degree angle (normal ship attitude). It doesn't make a difference as long as the prop is out of prop wash and not impacting the load cell.

hopefully this answered your other question on the criteria for an ESC and how to test it.

1) Response (highly critical to FPV racers and response in wind/turbulance)

2) Net-Max lift (now much the rotor (ESC, motor, prop can lift after lifting itself) ,critical to your heavy lift ship

3) Net-Efficiency (critical to sensor ships that need to travel to their destination, perform a long inspection, or maintain a position of surveillance)

There are many other criteria for a designer:

- cost

- reliability/durability (i like the burn-in process of your Herkules)

- size/fit

- brand

- etc.

Glad to be using those ESCs! How are you programming them? Is there a card to buy to do that and is it worth the extra step?

The DYS 40A Multicopter doesn't need programming.

The T-Motor 40 Air, [and scroll down]

No, no, no! I never said that! Of course with no air flow in 10min everything goes south. Actually I did said that. OK, let me rephrase: The Al heat sink block is there for one reason - to quickly "pull out" the heat. Than the air take care of cooling down the AL block. But the key-word here is the surface area. Since the surface area of FET is quite small the heat exchange between the junction in FET and the air is slow leading to overheating and eventually destroys the chip. To increase the speed at which the heat gets transferred from FET to air we use heat sinks (with large area and of course thermal mass to). And that's all. I guess some basic notion on heatsinks would come handy here as Darius pointed out.

Anyway sorry if I was misleading.

Hi Forrest,

Interesting work here.  I was not really following this thread until I happened to notice that you were talking about response rates, and fighting against the marketing hype of the FPV Racer ESC vendors.  I've also been extremely skeptical about the claims of high response rates.  I just don't believe that props accelerate that fast to make a meaningful change in thrust, and nobody has ever produced data to show they do.  And I've asked.  Even from people working on 10,000hz update rates.  No data.

However, even though I agree with you, I'm not seeing a lot of data here?  Did I miss it?  You seem to declare a winner, but I don't see the data list?

I'd also be interested to see more detail on your test rig.  I have to say, even though I'm skeptical of the response rates ESC makers claim, your measurements are even slower than I would have thought. 

As for Paul's statements that you are only testing drag racing results, I disagree.  How do multirotors change their angles?  They have to accelerate one motor on the end of a stick, and decelerate the other.  The resulting force-moment is what rotates the airframe.  So rate of change in thrust of the motor/prop, as you claim to be testing, is in fact, what makes a multirotor more responsive in flight.

I do understand what you mean :-) .The wire in old fuses is 0,2mm (AWG33) and jet it can handle up to 16A of current. And I just recalled this "monster":Micro filament on Tethered UAV andCyPhy Works  So bottom line you are right :-) There is  space for "thinning" down the wires.

And here is another question that bothers me for ages. Why, o why, we do not use higher voltage up to 12S or more with lover currents? Hmmm. I really can't see a good reason.

Excellent. Thanks for the answer.

So you understand where people go wrong:

1) as the Al block heats up rather quickly, the heat transfer is diminished because heat transfer is a function of heat differential, so the Al block isn't doing anything fast after few seconds.

2) if the FETS were exposed to the air, they transfer heat on 5 sides (top and edges). if you add up that total area, it is about the same as to top surface of the Al block (the only surface exposed to "cooler" air).

No problem on misleading. You corrected it and i've made some real bloopers before ... but, like you, i always have a good smile and confess when wrong. after all, physics can be non-intuitive and complex, which i why it is fun to learn. 

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