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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Very interesting, how is your opinion about hobby wing ones? I bougth those 30A to replace th heavy 40A that I have on my efficient ship and loose 80 grs but with this process I hope I can loose more weight; but now I'm in doubt if that 40 rc timer opto  aren't more efficient than the 30 hobby wing ones GLUP!, I'm going to try to check them first.

I should clarify. In all test cases, the ESCs were flown naked (the ESCs ... not the pilot). If flying fully wrapped, the results might be different. The DYS 40A Multicopter only weighs 13 grams naked versus the little guys that only weigh about 3 to 8 grams.  So the larger size can make up for the 40 gram weight increase (in a quad) in higher thrust and response. So if you don't fly them naked (or remove the heavy stuff and replace it with lighter stuff), then all bets are off as to which one is the most net-lift best.

Yes, them I thought that is nearly impossible for me, but if I nake them and put upside the arm (I have downside) I can lost a lot of weight, If I'm lucky and works well I can gain some more flying time :) that ship has an APM, next step is  change for a pixracer or something lighter than the APM with an ext compass so APM + floor to upside the compass, some grs less. I have thinner wires to replace and now Hugues distribution board is in the wishlist too for lightweight that copter. Thank's again to share your tests.

They are on the arm but near the main plate, I hope that the air there is enought to cooler?

Very informative. I've used the 3M spray and also Plastidip to coat bare ESCs.

Another excellent article Forrest,

I am a bit concerned that the 3M insulating mastic will also insulate the Fets from heat disapation, (versus an aluminum plate with heat conductive silicone grease.

Have you tested this?



Really good question. For a reason you will read here later, I haven't tested side by side sealed and unsealed ESCs. But, to understand the issues, we need to know the following.

The thermal conductivity of:

- Aluminum                      205

- Aluminum Oxide              30             (all Al heat blocks on ESCs are oxidized)

- Polyethylene (shrink tape)  0.33ish

- Silicone                            0.23ish

- Air                                    0.24

The amount of heat that will transfer through a material is based on    


                                                                Ak(delta T)/s      


A = Area                                                                       [want the surface area large]

k = thermal conductivity                                                 [want high conductive material]

delta T = delta temperature between the two surfaces       [need to keep the thermal delta large]

s = thickness of the material                                           [need to keep the material thin]

So the solutions are:

o Existing Design is a 2mm Al plate encased in shrink wrapWhile Al has an excellent specific heat. But 0.5 mm thick shrink wrap not so good in two ways:

   ... Al has excellent specific heat but the slab is thick and heavy

   ... Al oxide skin has good specific heat and is thin

   ... But the Heat Shrink wrap

       - traps the heat

       - not good at heat transfer (abates the purpose of the Al block)

       - think of what would happen to your car if you wrapped the radiator in a thick plastic sheet

    ... Usually hidden in the bowels of the ship so

        - not exposed to fresh air so delta T becomes small

        - not absorbing solar radiation 

o Al foil exposed directly to the air under prop wash (or a finely machined Al block with fins)

   ... much lighter than Al slab

   ... a finely machined block with fins would have > 2x the surface area

   ... partially reflects solar radiation (so environment adds less to the problem)

   ... new air unheated by ESC to keep delta T at a maximum to transfer away heat

o Just bare FETs covered in Silicone sealant

  ... lightest solution

  ... surface area similar to slab or foil as sides of FETs also help transfer heat

  ... red/black FETs mostly absorb solar radiation

  ... thin silicone layer 0.3ish mm puts layer on par with shrink wrap that has better conductivity but is thicker

  ... direct exposure to air wisks away heat


So for your application, what i'd suggest is to try an untreated DYS 40A Multicopter ESC. 

- Put it under the prop wash 

- If like my experience, it never gets warm (small to large ships duration ships but not true of freighters) so seal it.

- If it gets too warm or hot, then replace the Al block with Al foil and then seal all but air side of the Al Foil

Did you test the KISS ESCs?

There is a new edition with 24A continuous (shunt controlled) and 32bit MCU.

Interesting ESC.

Tried to order the 6S 30A version from GetFPV but they were out of stock. If someone sends me one, i'll test it (preferably with an XT60 plug on the battery side and bullet connectors on the motor leads).


how could I get wiring scheme for the above ESC ?

Electrical insulation is common with computer mainboards.

Not sure about bare bullet connectors and wires exposed to gusts and vibrations from propeller.

I would suggest to contact every manufacturer of ESC board to get written approval for the above procedure.

In case of drone crash due to problems with ESC, wiring, short circuit, the developer is lost with compensation claims.

Remember please, that under new model drone aircraft registration legislation by FAA, the developer is accountable for the experiments not approved by original manufacturer of ESC and other electric parts, boards installed on the drone.

In case of a single motor's failure in midair, ESC gets no cooling, the same for damage of the propeller.


before your technology enters into manufacturing phase I would suggest you to contact 2-3  genuine manufacturers of ESC boards to get advice and run a number of tests.


Did you contact 3M about your advised use of this electrical sealant ?

from pdf


3M(TM) Electrical Insulating Sealer 1602-R, Red 12/16/14 10.3. Possibility of hazardous reactions Hazardous polymerization will not occur.

10.4. Conditions to avoid Heat 




ingredients are highly toxic and cancerogenic



I read through that toxicity sheet and virtually all of the hazardous ingredients relate solely to the propellant and solvent.

Once cured it really shouldn't be a problem.

They didn't really specify whether the cured coating is problematic with heat or not.

Toluene and Xylene are somewhat hazardous, and in my life before they were known to be hazardous I am sure I have breathed in more than the equivalent of 10 gallons of each of them, along with MEK, carbon tetrachloride and TCE (and worse).

Definitely not advised, but I am 70 now and still going strong.

These days, because of insurance liability, everybody is much more conscientious about toxic materials.

Mostly you just need to use them correctly - I miss asbestos unfortunately it was never financially feasible for asbestos mine owners to put in sufficient safety measures to keep their miners from dying from asbestiosis plus it being used in ceiling tiles and insulation - probably not coming back.



This is Diy world Darius, all we do is our own risk. Buy a Solo to fly safe under your country laws.

The pilot always takes full responsibility. Because of damage incurred in a crash, liability cannot be traced to the builder or designer. So as a pilot, carry good insurance, make decisions based upon data you trust, and fly with 3 degrees of fault protection.

No ESC mfg will take liability for a ship failure. If their ESC blows in mid air, it is impossible to prove that it was the mfg's fault. Did the pilot fly into a bird that stopped the prop and cause the ESC to overheat and fail ... i think you get the picture. If your ESCs are getting hot, don't be an idiot. Fix the problem. As the pilot, it's your fault.

The ESCs on my applications run cooler when naked and exposed to open air. That means they are less likely to fail and thus safer.

Also, read the MSDS on the 3M product. All of the issues raised above pertain to the process of applying the silicone sealant from its aerosol can, not to the finished product which is chemically stable. Read the MSDS on an aerosol can and it reads the same. This product is safely used world wide. Read directions. Apply in a vented area ...

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