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:
- DYS
- Multistar
- Turnigy
- T-Motor
- Afro
- Motortron
- Quattro
- 3DR
- Spider
- KDE
- ZLW
- Aris
- EMAX
- 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.
Replies
this is becoming fun....
@Dorjano,
I invite Forrest, you and everyone to join my
Open Technology Park to study performance of ESC by make.
Forrest can manage Global ESC Labs and small staff of
researchers, engineers with university background
and study what he likes.
I can arrange for Smart ESC Conference to be held on-line
at SecondLife.
On-line lectures, seminars, multimedia presentations, live translation, Media Walls supported to play any video material or slides show.
Airframe arm is an excellent place to hide flexible, plastic heat pipes, manufactured cheap today in volume.
What can I offer next , I can start publishing bi-daily Smart ESC Journal and announce Smartest ESC Global Challenge
So I recommend all of us to support Forrest in his efforts to build Best ESC 2016 and donate him, since money is what makes us happy ;)
My friend from China manufactures 1kW thermoelectric generators. I advised him to build tubular thermoelectric generator for home use.
He asked me about substrate to support tubular shape.
My Las Vegas CES2016 Journal comes with solution to your problem.
Flexible 3D printed electronic circuits
So maybe the next generation ESC is exactly designed as 3D printed flexible ESC coming with printed FETs all-in-one.
follow-up
3D printed electronic circuits
http://www.printedelectronicsworld.com/articles/9263/optomec-3d-pri...
"
Optomec has announced its Aerosol Jet® technology is being used by LITE-ON Mobile Mechanical SBG (LITE-ON) for high-volume production of electronic devices. LITE-ON, a global contract manufacturer, has pioneered a 3D Direct Printing (3DP) solution that enables 3D antenna patterns and other functional electronics to be integrated into virtually any mechanical structure or cover - maximizing design flexibility, ensuring optimal placement and performance, and allowing slimmer product designs.
"With the flexibility provided by Aerosol Jet technology, our 3DP systems can print sensors, antennas, and other functional electronics onto plastic components and covers as well as metal die-cast insert-molded polymer frames and even onto glass panels and ceramic materials," said Henrik Johansson, Senior Manager, Technology Development Antennas, at LITE-ON. "We see Aerosol Jet as a strategic component of our 3DP solution, which has enabled us to expand into new markets."
http://www.idtechex.com/printed-electronics-europe/show/en/
from the last year conference on printed electronics I have got
printed heater, printed touch screen, printed sensors, printed antenna
so printed ESC seems to be next gen Smart ESC
"
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.
Sponsor. That is an offer I'll make to other professional racers that have earned their stripes by winning a major FPV race or freestyle.
I don't care if you are pig-headed or arrogant as long as you are willing to try to improve the sport through testing various designs that:
- accelerate faster than anything you have flown before
- are more durable than anything you have flown before
- are disciplined in your approach to winning
The goal is to create a ship that can out-fly anything humans can control and survive when its pilot crashes into a concrete wall at full speed.
My purpose is simple. Get manufacturers of ship bodies, VDEPs, ESCs, motors, props, controllers, cameras, gimbals, transmitters, receivers, and video output devices to improve their technologies faster.
So if you have a friend that wants an anonymous sponsor, have them friend me.
The same goes to manufacturers that I also work with gratis and anonymously to help them improve their products directly.
Which ESCs are the ones in the pictures? Just curious...
The DYS 40A Multicopter doesn't need programming.
The T-Motor 40 Air, http://www.rctigermotor.com/html/2014/esc_1223/285.html [and scroll down]
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 how ESC Response data is collected and summarized into statistics.
- The upper line shows when the command to change throttle was given, which starts the clock.
- The lower line shows real thrust.
- Each vertical line clocks 200 ms.
- The data collection rate is 100Hz
- An up or down cycle completes in about 5 to 20Hz depending on the rotor and voltage
- To get accurate statistics, 251 cycles of an up and 251 cycles of a down command are logged and averaged
- A 3rd order polynomial is then sent through an x/y plot of thrust change versus time
- The commanded change is about 250 net grams (grams after it moves the ESC first, thus ESC weight is a penalty)
- The evaluation point is when 80% of that command is achieved or 200 net-grams.
This is a typical chart showing how thrust changes with time (0.02 s = 20 ms). As one can see, despite our best wishes, nothing happens on the Mega Hz scale (a million Hz or 1/1000 of a ms). It's not until milli-second range, 0.01 seconds, that one can see a noticeable impact on thrust, but still only 5ish% of the commanded thrust change. The reality for those that subject themselves to hype.
Note that the blue line, Throttle Down, reacts faster than the red line, Throttle Up. So was this a spectacular demonstration of active braking?
Unfortunately for the hypees, this is passive prop drag reacting faster than the up stroke of a fairly good size motor. When i've tested ESCs with active braking, i can see it on the charts. But not on the thrust chart. Only on the volt chart as battery takes a quick charge and V spikes. By the laws of physics, there has to be an impact on thrust. But it apparently is extremely small relative to prop drag. As the technology matures, i'll keep checking. I know I'll see it someday. As a note, FPV Racer props are extremely high in drag. My efficiency ships, however, run lower drag carbon props so i think i'll first notice it there.
With this data, one then does two things:
1) calculate acceleration over the first 200 ms (in this case 4.53 g/ms^2 on up and 4.64 g/ms^2 on down)
2) calculate how quickly it achieves 80% of a 250g change in thrust (in this case 16.7 Hz on up and 19.3 Hz on down)
Hope this provides FPV Racers a bit of a reality check.
As a side note, 5Hz appears to be about the minimum for controlled flight in light winds when the ship is well made (mass close to the center of the prop plane for ease of rotation).
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