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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I totally support hard data arguments with open published reproductible measurements, without any "elite club" mentality (the typical : "if you're a real racer you have to use this brand/model ESC, otherwise you're so 2008").

Forrest is doing science with measurements. A scientific approach means the results can be checked and reproduced by peers. I can't check or reproduce what a FPV/racing guru says about his favorite ESC (and probably saying it because he's sponsored by the maker of that ESC)

If we stick to a scientific approach, so far DYS40A seems indeed to be the best ESC out there according to Forrest's measured data and that will remain until some other scientific data show another ESC to be more efficient.

Sure... it's a GREAT ESC for AP tuna boats. It's just NOT a RACE ESC. It's not equipped with the basic features necessary to be a RACE ESC.

Get BLHeli with MultiShot or at least OneShot125 on it. Get some Active Braking on it. Put it on a diet; get it down to a stripped weight in the 5-8 gram range.

THEN it will be a RACE ESC.

I am more than the sum of my voltage drops.

Why am I not surprised by this response?

... and to my surprise, the toggle in software produces a measurable difference  between efficiency and "sport" mode. It's a mighty fine ESC.

Thanks Hugues.

Also a confession. Given the seriousness of this topic for FPV racers and manufacturers, i'm in the process of taking a different approach to measuring response, to ensure that the data is correct. If i can measure it using two different approaches and get the same result, then ...

But, i have to admit, this effort at perfecting the response numbers is a bit silly on my part. Any FPV racer that thinks he/she can respond faster than 10Hz (let alone 300Hz) is focusing on the wrong thing. Focus on removing weight that doesn't hurt acceleration or frame stiffness. A 35 gram weight loss on a 350 gram 250 racer is a 10% improvement in acceleration. Use the best ESC, but more importantly, start shaving weight. Use true carbon, not the fake stuff used on flat plate FPV racers.

LOL ... and that perfectly summarizes why it's so easy to custom build a 250 Racer that can beat Paul's ship by 30% in a head to head race.

Paul - Think about what you just said. An ESC has electrons going through it's gates, responsible for the acceleration of your motors. Serious stuff. If you make the gate lighter, by necessity the gate becomes smaller. That is the problem with the above mentioned ESC that completely failed the response test.

@Forrest, is it internal resistance of the transistors you are talking about?

great question Martin. if you solve that, you are on your way to building a great ESC.

My guess (i don't mfg ESCs) is that it's not the components (transistors, FETs, etc.), but the board. that is why fundamentals are so important with an ESC. And why if you don't have the fundamentals correct, then the rest is all hype.

All boards use etched traces to conduct the flow of electrons from one electrical component to another. Some traces only send communication signals that do not need a large trace because the amps are extremely low. But the main flow that goes through the FETs uses, in a FPV 250 racer, up to about 10 amps per ESC on a fairly sustained basis during a race (if the ship is properly designed).

An optimal wire size (one that you have to lift into the air) for a 10 amp flow is 23 AWG wire or a wire with a cross section of .26 mm sq (.0004" sq). That means that if the trace is 1.6 mil then the trace width would need to be .25" (6.3 mm) wide. So if you have an ESC with 3 rows of FETS, then that means the minimum width of the ESC is over 1" wide. So measure how wide the ESC is and ask, What???


The two best ESCs out there solve this issue in two different ways:

- DYS 40 Multicopter uses two different and separated layers of board. One can be light (thin copper) and the other heavy (thick copper). I'm not sure they do this, but they can. They claim they do it for EMF reasons. Their board uses 3 rows of FETs and is 1" wide.

- T-Motor Air 40 that uses a single board layer actually solders a 14ish AWG wire to the FET rail to achieve it's 40 Amp rating (they only need 17 AWG to be optimal).

I hope that answers your question. It was an extremely insightful question.

How you distinguish true carbon and fake? I listened that I have to sand, if black is carbon if it's grey it's fake; is there another method?

What would you consider the optimum wire size for the ESC above? 16 AWG , or could you get away with 18 AWG? Is it different for the AC versus DC side because there are more wires on the output?


I'm thinking that the resistance of the traces shouldn't be the reason why an ESC is more or less responsive.

Resitance won't impede the flow of electrons, impedance does that. The voltage drop across the wires decreases the maximum power as some of the power goes into heating the wires. But the heating of the traces can't be substancial, otherwise the ESC would overheat very quickly.

I'm not an EE, but that's my understanding of the physics.

Sure... in a DRAG race.

Not in anything else, that any actual RACERS care about. And we have 40A ESCs that will eat these ALIVE because they start with short buses, 4oz copper pour, 16 ga power leads and they STILL have 4KHz refresh AND Active Braking.

You're trying to distill a race ESC down to a SINGLE factor... single, straight-line acceleration.

REAL racing is about handling; and unless you've been living in a cave for the last year and a half, if you REALLY race, you know that you need active braking to achieve that, and you NEED faster refresh than 10 or even 500 freaking Hz. *Derisive snort*

It doesn't MATTER How fast YOUR reflexes are. The faster the refresh, and the faster your ESCs can STOP the props as well as ACCELERATE, the more "Locked-in" your quad is. Why? Because it's not YOUR reflexes that matter. It's the reflexes of the FC, and how they translate YOUR INPUT into actual corrections in attitude.

Seriously; you have no idea. What you dismiss as "marketing faff" is actual different, better, smarter, faster and stronger technology.

True race ESCs are all being made from the latest generation, FASTEST, LOWEST IR FETs available with dedicated high-speed driver ICs to reduce overlap that causes desync. They are NOT made by kludging together yesterday's generation FETs in parallel to lower overall IR. :rolleyes:

You seem to think I'm an ignorant racer; I'm not. ;) I have design knowledge of my own.



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