Hi Dean,

Rather than have the ECL-Twin thread hijacked with this "screeching sound" subject, I thought this subject was important enough to warrent it's own thread as it's own Topic.

Will and I wrote that we are going to the new Jeti SPIN ESCs and Hacker motors to get away from the loud, annoying "screeching" sound from the Castle ESCs and AXI motors.

At the CA State Champs a few weeks ago there was a lot of interest in my ECL set up. It worked flawlessly all week end. Bret Buck and Howard Rush both liked the smooth unlimited amount of power, but they both commented on how LOUD it was commpared to Paul's quiet setup.

I explained to them that I talked to the techs at CC (Castle Creations) and was told that their CC ESC "SENDS" a signal to the motor windings (which are used to make all those musical sounds at power up) to MAKE that noise because the HELI flyers want it. It is made as the ESC tries to govern the prop speed as it goes above and below the target "set" RPM. (FWIW, my setup is "set" at 9,100 and varies from 8,800 to 9,350 during the pattern.) They said there is NO way to turn it off unless I wanted to go back to the early V?x version of their software and lose all the updates since, and lose all support for the product, etc. and they would not even tell me how to go back and were not sure if it could be done?

This loud screeching sound is very annoying at the quiet park I fly at. I also fly my E-RC planes between my ECL flights. My E-RC Hacker motors with Jeti ESCs are almost silent. This is why we went with the Hacker motors and Jeti SPIN ESCs on Will's twin. I know we broke a basic rule for scientific study by making TWO changes at once, so I can not say with certainty whether it is the AXI motor or the CC ESC that is the real problem? Maybe someone out there can help us with this info. ?? 

I would like to hear from other ECL flyer's about the sound of their systems?

You wrote:
"But that's not why I wanted to write.  You say you had "screeching" problems? Screeching is a problem most often seen on 3kW Pattern systems, and even then only when the currents are pushed very high. It appears to be an electrical noise problem (ironclad proof is a little tough on this one, as the problem tends to be sporadic and no one seems to have a storage oscilloscope at the field!) . The high currents combined with long wiring on the motor side of the ESC or control cable proximity to any high current wiring confuses the circuits and routines that figure out the motor RPM and commutation position. The result is mis-timed power application to the windings. Sometimes this happens when too much current is applied to the motor due to strange saturation effects, and other times because the inductance of the windings causes voltage ringing after the commutation cycle ends..

As a general statement, almost all motors and almost all ESCs have shown this problem, but only in strange combinations of motor, ESC brand, current level, and installation. It's a wierd problem.

You have to love the benefits of no GP, though!

later,Dean"

Dean, are you saying that on my AXI/CC setup that I may be able to lesson the screeching noise by making my motor cables shorter? They are long, and I have them doubled up right underneath my CC ESC with my long Battery cables also looped underneath (within 1/4") of my CC ESC. Could this be making the problem worse? Or, like you said, it is just random noise problem that we do not yet really understand? What do you think of what the CC tech told me? I was very disappointed. But I do understand that the Heli CC customers out number us by at least 10,000 to 1 

Regards, 

Thanks Allen,

Yes, that is when the noise is at it's worst. When the motor is lugged down to it's low RPM point at the start of a power draining maneuver the ESC must be pouring the coals to the motor to try and bring it back to it's set RPM, just like a throttle up in carrier.

What is unsettling is that it is still LOUD in steady level flight. Not screeching loud, just NOT quiet. I even changed out to a new AXI motor just to see if it was the bearings wearing out or something?

I don't want to say anything is wrong with the AXI motors. They are very powerfull for their weight and have flawless reliability. I use Hackers and E-flight motors in all of my E-RC planes, but I used the AXI on the recommendation of those on this forum and because they had the right power we need in ECL. I would still recommend the AXI and CC ESCs to anyone coming into ECL, they make a very good "turn key" system.

Hacker now has a 40 series motor that is closer to what we need. Their 50 series motors are Awesome, but a little large for our ECL planes. The 40 series is very powerfull and is only 9.3 oz. I am not as worried about weight as some are. IMHO: With our modern high lift airfoils all we need is POWER. I am much more concerned with the P to W ratio than I am with any of the "old" views about the gross weight being at some required "low" # just to make up for the lack of power in the old Fox, or whatever wimpy power source we were stuck with in the 1950s. Sorry, I did not mean that to sound so harsh. I just feel 3 oz should not prevent us from using a very powerful motor that will improve overall performance.  (WOW, I am going to get it now! The "light weight is sacred" group will surely have my head on a spike for this post!!!! And then the "Fly Fox or die" group will burn me at the stake!  )

I will be using my Hacker 40 in my next ECL plane. I wish I was not so lazy or I would switch out the AXI in my new Extra 300L ECL and try the Hacker. But they mount in opposite directions and would require major mods to my ducting, etc. 

The Hackers in the E-Twin are the 30 series and they still swing an APC 12 x 6 E prop! All our ECL Hackers have the rear cooling FAN. On my 40 series, they come standard. And they are quiet. :-)

Thanks again Alan, your comments helped.

Regards, 

Hi Guys,
The screech that I am talking about would be obvious. It is a howl, and the power drops off! Nope, I wasn't talking about the same thing you were, Rudy. All the stuff about short, twisted wiring is for naught, even if helpful. Alan was probably talking about the same thing I was, and the governor was not used for carrier at all. Right Alan?

General rule, short wires are better. The two wires from ESC to the battery should be twisted together. The 3 wires from ESC to motore should be short and twisted together, or they should be so short that twists are not practical. The problem(?) is this: at any one moment, two wires are providing power, and the third is a no current "sense" lead that tells the ESC the position of the armature. If that sense signal is corrupted by induced field from the first two wires coupling to the third, then the ESC can mis-fire, kinda like pre-ignition.

The tests we did, a while back, showed us that the CC governor is the fastest one out there: it corrects for load changes faster than anything tested. I guess the acid tests are a comparison in bad runway wind and in bad turbulence. Whip-up and tempo changes in the maneuvers are the enemy! 

Rudy, what version SW cauases this? I gotta talk to the boys at Castle. Why don't you try a faster switching frequency on the CC ESC?

Dean

Hi Guys,
The screech that I am talking about would be obvious. It is a howl, and the power drops off! Nope, I wasn't talking about the same thing you were, Rudy. All the stuff about short, twisted wiring is for naught, even if helpful. Alan was probably talking about the same thing I was, and the governor was not used for carrier at all. Right Alan?

General rule, short wires are better. The two wires from ESC to the battery should be twisted together. The 3 wires from ESC to motore should be short and twisted together, or they should be so short that twists are not practical. The problem(?) is this: at any one moment, two wires are providing power, and the third is a no current "sense" lead that tells the ESC the position of the armature. If that sense signal is corrupted by induced field from the first two wires coupling to the third, then the ESC can mis-fire, kinda like pre-ignition.

The tests we did, a while back, showed us that the CC governor is the fastest one out there: it corrects for load changes faster than anything tested. I guess the acid tests are a comparison in bad runway wind and in bad turbulence. Whip-up and tempo changes in the maneuvers are the enemy! 

Rudy, what version SW cauases this? I gotta talk to the boys at Castle. Why don't you try a faster switching frequency on the CC ESC?

Dean

Hi Dean,

Thanks for the good info. Sound is hard to explain in words. One man's Screech is another man's Howl. Just to be clear, we are talking ECL motors here, not ex wives, right? 

To give you some idea of the sound level. At the last contest (CA champs) they had a large athletic field with four circles with room in between them. Bret and Howard were sitting at the far corner of the field. I was flying at the farthest circle from them, with all circles active with 2 stroke engines. They both clearly heard my plane during my whole flight. If a 2S is flying next to me, I can still clearly hear my motor when I'm flying. To me this is loud, and needs a solution. If I fly my E-RC planes anywhere near a muffled 2S I can't hear my motor at all. BTW Linheart also reported a screehing sound in his AXI/CC system in his beautiful Bearcat.

I'm a little confused by your post. I understood you to say that "all the stuff about short twisted wire is for naught" ...... then you state that we should shorten our wires and twist them? Please explain.

I like the idea of shorter wires. Mine are all the same length as they came out of the package. This is very long with the CC ESC. I will cut them and twist them, both power and motor, to see if this helps.

What ESC switching speed do you recommend for my CC? I am using the JMP-2 SW if that is what you were asking?

Do you (or Mike, or anyone else) have your CC ESC settings available for us to see? It would be informative to compare notes now that we all have more flights on our planes at the end of the season.

After 150 flights I am very happy with my ECL system. It is as smooth and strong as any 2S system I have seen fly. And yes, that includes the HI ZOOT setups! ;-) After flying in 4 contests this year and seeing the lack of reliability/consistency in the 2S engines, I am even more of a fan of our ECL power systems!    ......... Thanks again for all your help.

Regards, 

About Pete Mazur's CL carrier plane, no he isn't using a governor---it is setup for a throttle control via the standard carrier third line.
His  "screech" is really just that--a bone rattling shriek that sends shivers up the spine from a CL circle away! Gets your attentions, like 10 inch finger nails dragged along a 10 foot chalk board. Not a wimpy little whine!

Okay, that bone-rattler is what I was talking about originally. It comes from some sort of electrical noise problem in the airplane, and the motor is screaming because it is being torn apart from the inside. I'm not kidding. This is the "high current only" problem. Some combos of ESCs do it with some motors and not with others while some motors do it only with certain ESCs but not others.

Rudy, what I meant by "for naught" is this: the wimpy little whine is just the switching frequency of the ESC. It's 7 KHz as a default, and can be raised to a nearly inaudible 32 KHz in the castle-link software. Try it. This will make the ESC run a bit warmer! Shortening the wires will have no effect on that, but it will add lightness!

Some motors are more sound-dead internally. The AXI may not be a winner in this regard, but at the time it was both good and cheap. I'm kinda eager to try the various Rimfire motors. The setup, as I envision it, involves running a big load (both diameter and pitch) on the governor at a much lower RPM and current than is possible if the governor went to its internal "full throttle". At the internal half-throttle, the ripple current at the ESC switching frequency will be at a maximum, and that ripple current is a signal being sent to the ... motor windings, magnets, prop shaft and prop which have now all become a speaker! At full throttle, the ripple current disappears altogether, and so will that whine. If you prop down in pitch and raise the timer output percentage and RPM to keep the same lap time, the whine will reduce. You won't like the airplane as much in the wind, however.

Let's be scientific: try raising the switching frequency to 14 KHz. I think that's the next step, and see if the whine note changes. if it does, and if ESC temps are good, try the highest setting.

later,
Dean