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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LOL... this is great info... if you're flying a plane.

Absolutely irrelevant to the response time of a fast ESC to an acro-mode FC.

Your test rig is based on PWM; that in itself slows down the entire chain to the point that a 100hz sample rate is irrelevant.

Sorry... the proof is in the pudding, and people who really fly can feel the difference in their quads, and they're able to fly faster and control their quads at higher speeds; this is resulting in real world, empirical evidence in the form of ever-decreasing lap times and being ABLE to fly at speed in crazy spaces like inside a house or a parking garage.

Just because you haven't figured out how to quantify it doesn't mean it's not real. ;)

Good hunting!


@Forrest, thank you for that fantastic spreadsheet, a very useful tool.

Can I divert this conversation away from racing quads for a moment to ask a question I haven't gotten a good answer to?

I'm rebuilding a 3DR X8 and considering swapping out the eight ESCs that weigh 21g each with the tiny miniquad ESCs that weigh 4g each. Both are rated at 20A with a burst to 30A. This would save me 136g! (Not including the single additional ubec I will need since these are opto.
An example of the ESCs I'm considering are the LittleBees or tiny DYS 20A.

Does anyone see a problem with using a BLHeli miniquad ESC on a big X8? I know it isn't designed for a platform like this, but does it matter? There must be some disadvantage to loosing so much mass. Will I lose efficency to undermine my weight savings? Are they less robust in the long run? Do they handle low KV motors as well?
The 3DR copters use aluminum arms which can act as a heat sink if I shrink wrap over the whole arm.

Thanks for your opinions.

@ Forrest

I had a similar discussion with my son regarding 144hz monitors. I argued without trying one myself first, that he couldn't see the difference between 60Hz and 144Hz. My argument was that our eyes can't see the progression between frames above 24 frames or so, and with interlacing etc 60Hz was enough. I was horribly wrong. 144Hz is so much smoother and responsive I bought him a 144Hz on the spot after trying it. (to his delight!) I'd only buy 144Hz from now on...once there's a larger sized one to replace my 42" 4K 60Hz one. :-(

My point is that I think the imperial evidence we assume to represent human capability is not based on a specialised trained eye specifically looking for flaws or latency in a system, but of capabilities resulting from a double blind test. I think we are seriously underestimating the resolution of both spacial and time of human capability, and what we think is "fast enough", is not for some, who are constantly honing their skills to optimise them. Take F1 drivers over "normal" car drivers. Humans are simply more analog and they can be trained to react faster to stimuli, beyond the capabilities of "conventional folk" like myself. 

What would be interesting here is more data on what humans can actually perceive and respond too, and how that relates to the hardware being used. Until now such studies are unlikely to have been very mainstream (maybe relevant for military pilots etc) however, from a design perspective I always like starting back from human capability and desire. In this case the "Ultimate world best ESC" should maybe take the human eye to hand coordination skill as a reference point, and design a system that is imperceptibly smooth and latency free from there. I think electronically, and even through RF transmission, this should be achievable technically.



@ Paul

Without wanting to make your point for you, there is a massive field of variables that can lead to better lap times....starting from what pilots had for breakfast. ;-)

The question, to progress the discussion here would be to test pilot skills (maybe by analyzing logs) to see what differences, if at all can be perceived by the human "machine", and how that relates to ESC performance as well.

I've been flying the DYS BL20As on a number of miniquads; they hold up well and perform well under pretty heavy loading with 6045 props on 1806-2300 & 2204-2300 motors and 3S. I get awesome runtimes; 30 min from a 30C 3S-4000 on my G10 Flying Brick build at approx 680 grams in LOS mode with a Mobius and 27 minutes at 760 grams with SJ4000 in a hardcase the same configuration and weight as a GoPro. The Xiaomi Yi and ABS holder are right in the middle at around 720 grams and 28 minutes.

You're running in the neighborhood of what; 8x 2216-850-950KV? 4 kilos AUW? 

Your peak current draw from an octo will likely be considerably less per ESC, particularly since you're not flying acro with stall-induced LRA current draw to worry about. But constant current may be higher (aside from the FFF adrenaline junkies I know who only know ZERO and FULL THROTTLE).

If you're concerned with longevity, you may prefer to go with the XM30A for a couple $$ and 3 grams more. IIRC, it comes in at 7-8 grams with the motor wires removed.

BLHeli has one quirk; it will only cal up to 2020ms. If your FC sends PWM that exceeds 2020ms, it considers it a corrupt signal and shuts down, so you need to make sure your upper limits are less than that in the motors tab. This manifests most obviously in the fact that you can only go up to about 80% rotation of the knob when testing with a servo tester.



Which ESCs are the ones in the pictures?  Just curious...

You really should just hit the delete button. This is about data, not belief. This isn't for you. It's for people that understand learning curves and willing to try two ships side by side. Don't shake your faith. Don't read this. Delete!

Let's say you have two cases. You tell me, which is the better ship (endurance and response). Because the following is exactly your question:

Case 1: The ship weighs 2 kg and generates 4 kg grams of thrust.

Case 2: the ship weighs 2.136 kg and generates 4.4 kg of thrust.

Hint:  F (force) = m (mass) x a (acceleration) or a = F/m

P.S. An important note. Most of the weight of ESC is the wire, heat sink, and shrink wrap. If you run ESCs naked, then the wires on both are the same and there isn't a heat sink (not required when putting the ESC under the prop wash). So the difference in ESC weight of the BLheli miniquad and DYS 40A Multicopter ESC is 11 grams x 8 = 88 grams on a X8. The difference in thrust is over 400 grams more with the heavier ESC and far higher reliability.

Completely agree JB.

This is why all data must be backed up by real tests. There is no better test than a drag race. It takes phenomenal human control to lift a ship at full power, rotate it, change its direction of momentum, and then put it through a target 50 meters away while still at full throttle. It can only be done with professional racers and those that have won races. Every time, the race (for some strange reason of physics) backs up the following equation.

                                                                      F = ma


What the pros see is a different form the the same equation. They experience

                                                  a (acceleration) = F (max thrust) / m (ship AUW)

So if there is a law of physics governing the outcome of a test, why do the test? The reason is that every FPV champion i've met is arrogant as hell about their sport. They insist on the "Charmin" test. So i give it to them.

P.S. By the way. The reason why you can see a difference in update rate on a TV with "slow" eyes, is that your brain update rate interacts with two other frequencies:

1) the camera that recorded the original scenes update rate

2) the TV update rate

The faster those rates and the less they are linked (note that 60Hz is a simple multiple of 30 fps where as 144 Hz and 30 fps are not), your "brain/eyes" will see fewer frame transitions, making transitions between frames appear smoother.

With "fast" ESCs, you can see the difference ... on an oscilloscope. But what counts isn't what you see, but what translates into thrust. So a 300 MHz difference translates a max to 0.3 micro-seconds of thrust or 1 gram of thrust. So if the ESC designer has ignored fundamentals of ESC design, which so far all "fast" ESCs have, then the "slower" ESC with greater output will respond faster in actual thrust output.

If the drag race is short enough, the "fast" ESC will win every time. But the race can only be 0.1 mm long! After that, the ESC that first has the fundamentals correct (and the fast stuff second) wins every time.

Those are the 2nd best ESC out there, the T-Motor Air 40A. Really good ESCs. Obvious focus on fundamentals. And the frequency setting that is programmable actually does exactly what they claim.

This is utterly bunk science.

You are STILL thinking ONLY in the frame of reference of linear acceleration, and I've already explained why that's a specious argument at best where multirotor aircraft are concerned.

I've explained why modern quads need faster refresh, I've even explained why you're wrong about the fundamental construction differences of these dinosaurs vs modern race ESCs, and I've even pointed you to valid real world testing that SHOWS the difference. 

Cheers,  and have a nice life in your little altered reality bubble. The rest of the world will continue moving forward without you.

Paul, I know what you are talking about.

The best way to show the real time results would be to put 4 of the esc's that Forrest is talking about on a good quality ZMR 250 with a good F3 Flight control and Beta Flight loaded on it abd BLACK BOX. Take it through a race course with a FPV seasoned racer in control of it. Fly and time the course. Download the BLACK BOX log. Take the same Quad and change the esc's to any of the good  39x series esc's with BLheli and run the same test again. This will show the real truth. This going to show what the FPV Racers already know. If some of the others don't believe this it would be well worth going to Boris B forum and reading up on how fast this technology is changing. After reading alot of posts I am beginning to doubt if some are even using Beta Flight, if they were then they would know why these esc's are not used. The BLACK BOX is very neat it shows pilot input and also shows what is going on with the FC and esc's in real time it gives real FACTS and figures.

Happy flying guys.

Excellent Paul. Finally someone interested in science and tests.

Since i've all ready done that and know the outcome, i'll repeat my message to those invested in ESCs.

To Manufacturers: All of the advancements you add to ESCs are fantastic! But get the fundamentals right first. Without the fundamentals all of the great good you are adding won't outperform the old that has the fundamentals optimized.

To Users: If the manufacturer doesn't heed that advice. Then don't reward them by continuing to fly their products. Buy from those that get it right. Fly those that get the fundamentals optimized and then add the advancements.

Fundamentals folks. It's critical.

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