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
Thanks for doing this kind of painstaking expensive tedious work, you are an asset to the worldwide community.
I'm in the difficult task to choose an esc from HK (http://www.hobbyking.com/hobbyking/store/__1409__1406__Multi_Rotors... ) to my little baby without all this knowledge, I read something about oneshot but no shure what it's means? Max motor consumption says 17A
Another shop isn't a possibility for me, I have to make only one order with all components. any suggestion is welcome.
This one doesn't have a blue case, but it says the right things.
http://www.hobbyking.com/hobbyking/store/__77169__DYS_F40A_OPTO_ESC...
Don't worry about one-shot. It appears to be a good theory with no measurable improvement in performance (efficiency or response). Also, i was hopeful for active braking or regenerative braking in terms of response on down throttle. So far haven't seen anything real performance difference there either. but i'm still hopeful.
Thank's Forrest, take a look,
Forrest - thanks for the research. I learned from your testing. I've been waterproofing with Corrosion X and liquid tape, but that 3M sealant looks like a better match in some cases.
I no longer use hot glue on any of my builds. When it heats up, it lets go. While mapping cotton fields in South Georgia, my PixHawk equipped DiscoPro sat in the sun for about 10 minutes as I modified and uploaded the flight plan. When it came back, the arming switch and buzzer were swinging free. Oops! (That was about the only time that I liked the DF13 connectors.) You might consider a more heat resistant adhesive for ESCs.
Darius: Got any photos of how you mount your ESCs?
absolutely ... any suggestions? also by the time you get enough hot glue on the subject to make it stick, it's heavy (so needs more energy to lift and thus generates more heat).
I over use liquid tape. It takes a while to cure, but holds well; and removes well when you peel it.
http://www.amazon.com/Gardner-Bender-LTW-400-Liquid-4-Ounce/product...
But it comes in white!
Out of curiosity, why do you use dental floss instead of zip ties? Weight? (As a Scoutmaster, I should be tying more knots...) Have you ever had dental floss cut through insulation?
Thanks again for your patience. Asking Darius for photos has run him off in the past.
Joe: but now doesn't work, please think another strategic ;)
Some people have forms of autism. This is not their fault. They deserve to be understood. Their views have a right to be written. Autism is simply a brain that is brilliant in some manners but usually lacking in understanding social cues.
I remember working with one young lad. The first thing he said was, "I have autism". While his words surprised me, it allowed me to mind set how he might interact, which made working with him much easier. Maybe more will learn to do that
I do not mind caustic discourse as long as there is a delicious fruit to be plucked from the lye. But, when the discourse is caustic and lacking value ... I take the lead from JoeBob and use the wonderful function DIYDrones offers in listing the person's name first ... as we also have a right to choose what we read. An interesting side note on Autism is that conflict makes them feel alive, but is at the same time harmful. So i'll do my best to help and not harm.
We understand you, and it is OK.
Thank's Forrest, always instructive, as you say, I have friends with problems too, but I know them and all It's ok, I can understand when they are trespassing a bad moment, shure the correct explanation; I'm going to inspect DD function too; many thank's.
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