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.

Views: 21472

Reply to This

Replies to This Discussion

"What do we hain from this? NADA !!"

That should read:

"What do **I** hain from this? NADA !!"

Your particular scenarios and applications clearly don't stress your ESCs, and you have no specific need to save weight or to guard against water, so your answer is absolutely correct.. for you.

Personally, I have no particular need to save weight or to dissipate heat (although welcome benefits if available), but I'm very interested in the water proofing aspect as I often fly in adverse conditions and over water (sea mist = death to electronics).  Any advance in this direction is very welcome research, I don't see the negativity.  If you don't like it, or it's not useful to you, move onto the next discussion!  Good discussion, debate and debunking is fundamental to good science, hating for the sake of it isn't.

That said, I'm not convinced about small bullet connectors (very easy to come disconnected in my experience) or about situating the ESCs like that under the props - surely it must have negative effect on thrust.

How are you even creating any water proofing when you use such bullet connectors ? So my point is what is the exact target. To save weight ? Water proof ? Improve heat (which should not be a concern when set up properly with the appropriate ESC for current draw...) or long term reliability (conformal coating). 

If you are concerned about water or sea mist you are first of all using the wrong FC.. IF anything ur FC is going down first before your ESC or motors since its much more sensitive. 

I would gladly applaud the making of the "worlds best ESC" i simply dont see it. sorry. This is a forum i am just stating my opinion. Anyone can coat a piece of electronic with a conformal coating... it doesnt make it worlds best. 

Absolutely. There is an impact on lift. When there is something below the prop wash that is connected to the ship, it puts a negative load on lift.

So how much? In a previous post here i discussed that. But to satisfy your own curiosity, do what i did. Hold a gram scale under the prop wash with a motor running at 60% throttle. You will be amazed as i was. take that reading and convert it to psi. then do the math by looking at the si of the edge of an ESC.

Please Tony, read the article, He didn't furbish esc, he test many of them and choose the better from that group and open to test others if you know another better not listed:

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

Opps! Sorry. Guess I wasn't clear.

The DYS 40A Multicopter ESC is the best in the world, unmodified. The improvements we've discussed here have nothing to to with making it the worlds best ESC. It all ready is.

The other part of this forum topic is simply discussion on how to make it even better:

- lighter (even more net-lift efficient)

- lighter (even higher maximum net-lift)

- lighter (even greater acceleration)

- run cooler (more efficient, higher maximum lift, greater acceleration)

- more weather resistant (more reliable)

- more dust resistant (more reliable)

- etc.

Umm I'm no aerodynamicist but that sounds like somewhat hokey science to me.  Downforce is not just going to be reduced by the equivalent of the area of the top edge of the ESC, there will be all sorts of other aerodynamic interactions, vortices etc with such a large flat area and multiple edges.  But the ESC doesn't have to go there of course, certainly none of my ESCs run hot enough to warrant needing to put it directly under the prop wash.  I have my ESCs in my CF tubes at the moment and they barely get warm.

The trouble with shrinkwrap (and inside the tubes, to some extent) is that if they do get wet, the water tends to get trapped inside the shrinkwrap  and the tubes.  A treated component like this, if it worked, would be pretty cool (no pun intended).

Not to mention problems with TOO LONG WIRES as one of main reason why ESC becomes hot...i suggest author read some text about it all over internet,here is one example...there are many..

Excellent point and reference.  

For those that don't understand Emin's point, a simple example is a water pipe in the kitchen. Ever been in an old house where you shut off the water and you hear the pipes rattle? That is the momentum of the water suddenly being curtailed. The water slams into the end of the pipe, tries to take the pipe with it, and if loose, will audibly rattle against the wood joists. Electrons are similar. And capacitors help absorb the backlash. The longer the wire, the more electrons that need to be absorbed (stored).

Let me quote your reference.

"As a rule of thumb, for every 4inch/10cm extra length/distance between battery and ESC, add an 220uF extra capacitance ...". What the author is saying is another rule of thumb, "2.35 uF/(in*A)" if you go into his calculator.

The capacitors on the DYS 40A multicopter are twin 330 uf. So based on that rule of thumb, maximum wire length between the battery and ESC assuming 15 amp max is 18". At 30 amps, 9". At 40 amps 7". If you get a lot of momentary 60 amps spikes, 4". It comes with 4" wires.

The above FPV 250, the total length of the ESC wire is 4". 

But what i didn't explicitly state (so thank you for seeing the oversight), I always put the ESC under the prop wash but also under it's outer edge. This:

- keeps the battery ESC wire short (with an X about as short as you normally do).

- reduces drag to nil (the primary prop wash, which would be overkill) is about 1/3rd the way out from the center of the prop.

You are really tolerant man like very few around here,if any...even if i not agree with your ways of posting things i will respect you for that...please take my apologise for all the hard words i used...i am sorry.

Bullet Weight - There is a distinct advantage to large bullets in that they are less likely to accidently disconnect. And if i like to save weight on bullet connectors, then why do i sometimes use an XT60 (6.2 g) on the main battery plug?

Given that optimal wire size drives the bullet connector size (the wire must fit into the shaft), on a quad with 20 bullet connectors between the ESC to motors and battery (weight varies between connector suppliers):

- 3 & 4 mm bullets add 23 to 31 grams

- 2.0 mm bullets    add 11ish grams

- 0.8 mm bullets    add  5 grams

So for an FPV racer using 2 mm versus 3 mm bullets, the acceleration of the lighter ship will be 5% quicker!  That is clearly enough to win or lose the race.

But small bullets come loose. Yes, they can. All lines running to/from the ESC should be tied down (use dental floss to practice knot tying or use slightly heavier zip ties). Do this no matter what the bullet size.  If they are tied down properly, they will not come loose in flight. Ever. Check all connections after a crash for wires that pulled and periodically. If the ESCs are under the prop, connections are easy to inspect.

So why slow down your racer with more weight? Why shorten flight time? When all you have to do is learn how to tie a square knot using Minty Floss (my big bro taught me how :-).

Why do i sometimes use the heavy XT60 connector? I'm a hypocrite? Excluding the 250 Racer that can easily spike to 60 amps, most of my ship don't exceed 20 amps. The XT60 is 5 grams heavier than a right-sized connector on those later ships. If going for a world record, i'll take the extra 30 seconds and tie down the battery to the power module connection. But for convenience of every day flying i want the ship to:

- be easy to connect and disconnect to swap batteries without having to tie them down

- on a crash, to jettison the battery, which the XT60 performs nicely (saves the ESCs and frame)

Hokey Science--You gotta love it. Skepticism is good. Here in the states, every state is known for a trait. Texas ... well you know that one.  Now Missouri, one of our southern states, is so proud of being stubborn and obnoxious that it's called the "Show Me" state. Sometimes i swear that i was born in Missouri. i question everything. ya ... i know, big pain in the ass.

Anyway, Fnoop, from one mule to another :-), this Buds for you ...

Here is the photo of the computer screen measuring rotor output @ 544 grams.

Here is a photo of taking the airflow readings under a prop (i risked my life for Fnoop!).

9 m/s (haulin' #%$).

Here is the ESC on a hot-dog stick under his friend, the prop..

Here is the force of the ESC on a hot dog stick under his friend, the prop, with and without the motor wailing.

So the force in this case was 1ish grams of drag.

So do you need to put the ESC under the prop? Maybe not. Maybe it will do just fine in the airflow from ship movement or stagnant air. Test to find out.

And also keep in mind that by locating the ESC along the mast going to the motor (wires no longer have to traverse that distance), you eliminate 24" (0.6 m) of wire weight on a quad. And that is a lot of weight (12ish grams of wires versus 5ish grams of drag).

P.S. Nice job Fnoop on knowing how to motivate me to "get 'er done" and answer the dang drag question. You weren't the only one that didn't believe it (me included a few years ago).

I was in doubt if use connectors (in case of crash they can disconnect) on my future racer or soldered wires to save weight, perhaps connectors is a better choice?

Reply to Discussion



Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

© 2020   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service