Bubblehead575

Cliff

There are a couple of us on the other side of the divide in Denver with the Nuance. Like you I left the hobby about the same time when electrics were just being introduced. I have been back about 3 yrs and I have had to learn a lot over that time to prevent issues that are self created. I am very happy with my Nuance (had one for 2 yrs) it has the Pletty Xtra, Castle 80HV and Futaba servos, however I have had similar issues with smoking the ESC. I have been through 4 of them (without damage to plane, just a little smoke smell). I run a separate battery for my radio, so I don't have control issues when the speed control fails and may or may not have power to motor. In my case the failure is normally preceded by a squeal or screech similar to a fan belt in a car.

I have discovered the issue is resistance caused primarily by my bad soldering, or connection (this is causing the ESC to fail and short. There is a K-Factor article in one of the recent issues on this) I know how frustrating this can be, as I have struggled myself, and I had lots of help from some great guys.

As far as setup, I agree with Arch, I run mine at .5 incidence and 270mm from the back of the canopy. And it does seem like you have to raise the tail a lot to get the stab on zero, but it is correct and the anhedral stab makes it a challenge to get the incidence right.

Cliff_B

Thanks for the reply Bill, I also noted a squeal prior to failure but failed to recognize it as a issue. With the stab at 0 deg the wing is only at .2 deg positive . But to get the stab to 0 the tail is about 10" off the table and the airplane is at 6-8 deg down ward slope. I got that far when setting it up but could not under stand how that could be correct. I have the gear back in already, ( a little heavier I'm sure) need to replace a carbon tube I had the batt mounted with and install a new ESC. I will reset the wings to .6-7 deg with the stab at 0 and see how that works. There are to many of these planes out there for it not to be a decent plane.

I did inspect the solder joints on my wiring and they looked good, there were no issues on the joints I put together. I pre tin each conn and make sure the solder flows freely as to avoid problems. That's not to say that's not what happened but I haven't had issue with any other plane, I do have the k factor you are speaking of and will re visit the article thanks, hope to see ya on the pattern trail. Won't make the fall albq. This year.....have to work.

Bubblehead575

Cliff the high resistance connection can be anywhere from the battery to the motor. It does not have to be a bad solder joint. My last incident was caused by the arming plug. It had been arcing a little more than normal and I was thinking about cleaning it, but decided to fly first. I too off and in my first down line I go to power up and I hear that squeal. By the way the problem normally shows itself when you are throttling up from a power off and in a vertical down line where the motor is spinning with out power and as you power up coming out of the down line, you hear the squeal. Just land and hope you have not damaged the ESC. My last one still worked but power was down, so I swapped it out and sent it to Castle for inspection/repair. They sent me a new one. Damaged beyond economic repair.

Is there anyone out there who knows how to check an installed system for the voltage drop and resistance that causes it, so we can identify when this situation may be identified before it happens?

Perhaps this is a good topic for another thread?

ltc

My Feedback: (3)

If you have a handheld DMM that can measure millivolts, it is a straightforward task to perform a basic measurement.
In addition to the DMM, you will need a set of voltage probes with pointed/sharp tips (these will help penetrate the heatshrink without any damage). Or you can use alligator clips, again if you can slide the heatshrink back far enough.

Place the DMM (+) lead on one side of a connector/connection (could be an arming plug, ESC to motor bullet, battery to ESC); press thru the heatshink if necessary or carefully slide back the heatshrink if possible
Place the DMM (-) lead on the other side of the connector/connection.

Verify that you are reading 0.000VDC with the motor armed but not spinning.

Now, with the model restrained ...(an assistant is helpful), advance the throttle, placing current flowing thru the connection under test/measurement. Record the DMM reading, then turn off the motor (preventing any damage due to lack of airflow or increased temperature).

If you read a significant voltage across the connection, you have a bad contact/connection/soldering joint.
If you have telemetry or a clamp on current meter and can determine the current that was flowing when the voltage was measured, calculate the resistance by taking the voltage measurement (volts) and dividing by the current (amps)

As a secondary test, you can use a thermal probe (direct contact or non contact IR) and measure the temperature rise of the contact when current is flowing and compare it to when current is not flowing (ambient room temperature).

For example, if you had 50Amps flowing thru the connector/connection and you measured 100mVDC, the resistance would be 0.1VDC / 50A = 2 milliohms (2 thousandths of an ohm). That is a good number.

There is much more advance physics and theory behind connectors (really), but in general, if you are under 0.5VDC (500mVDC) under full load current (assuming gold connectors are used), then you should be OK for now.
Higher than that and you connector/connection is not really a connection, but in fact a resistor.

Think of it this way....
An ideal connection is 2 conductors held together by a bolt and nut. Lots of surface area, lots of contact pressure. No matter how much current you force thru it, you won't generate a voltage (drop), so there is no problem.
Unfortunately, connectors (bullets, Deans, pin/socket, blade/socket, etc) are NOT bolted together and therefore aren't perfect. Once you get too large of a voltage drop across, it's not a connector, it's a resistor.

EHFAI

Adding to what ltc says - a resistor is a heat generator (think toaster). Feel connectors / solder joints after a flight - anything hot is a problem.

Cliff_B

Finally got my Nuance repaired and back in tHe air with a new OS 1100 ESV ( thanks Dave for the help setting it up) dialed in 1/2 round positive incendence set the cg at 160 mm, and it is a differant airplane, adverse roll coupling is gone along with hard pull to canopy, working on getting throttle tech set, had it at 35 and power seemed a little low, rpm at start about 6050, backed it off to 30 and rpm came up to 6250 at beginning of flight and was 6170 so only a drop of 120 rpm. This might be off a bit cause I was working on trimming and landed several times, will continue to fine tune this.

Cant seem to catch a break with this airplane, third flight....odd noise sounded like a motor screech and seemed to be connected to the speed of the plane, after it going down with the flaming YGE esc I was pretty nervous so I landed, checked canopy all control surfaces,checked servo mounts, revved motor to max several times... No noise. Connections on batt and esc were cool, motor was cool. So I changed batt and went up again, there it is again a screeching noise, landed and repeated process of trying to identify the noise. I put it up again still there made a long vertical climb stalled it around and down it came, high idle on so no brake, about 2/3 way down the left wing panel seemed to explode. I pulled the nose up and it responded so I eased it to the runway and set it down, I found the the covering had lifted on the left wing panel, what a mess. The red color had lifted and took some of the other colors with.

Once home one I was able to get the red off after lifting the other colors, trip to hobby shop and I found some Enconocote in red that is very close. I was able to get it down and it's not to bad, hard to tell what happened. So ready to go again plane is getting much better and I feel like I will be able to make friends with it if I can keep it together long enough, after adding the heavier esc and repairing the landing gear blocks I will have to move the batt tray back about 1 1/2 in, not to big a deal just need to do it. Inspection of right wing panel showed some wood exposed where the red is wrapped over the leading edge, I suppose that's what happened to the left side and hopefully that's what the noise was. Thanks for all the help with this.

mups53

My Feedback: (41)

Guys for your information there is a new improved version of the Nuance available now called the Etude pronounce A Tude.
http://www.f3aunlimited.com/bj-craft...gn-spring-2016
It incorporates a Nuance fuse with changes to the wing and stab.
It's a lower cost No Frills alternative. It's for the loyal Prolog and Nuance fans that are still out there as well as those who like the plane and we're sorry to see it discontinued.
If by chance you'll be coming to the Toledo show next weekend come by and take a look. The show model is also for sale right now.
Thanks, Mike Mueller

OhD

Has anyone done a careful measurement of the decalage between the wing and stab on the Nuance? I've consistently measured the wing to be about .2 degrees negative with respect to the stab. Doesn't seem right but it flies with just a small amount of up trim which could be do to cg placement. More flight trimming is necessary but I'd like to start from a good baseline.

Jim O

tewalker01

My Feedback: (5)

The following is from a BJ Park design discussion for the Nuance

Basic incidence of Nuance is:
- 0 dgr horizontal stab
- 0.2 dgr main wing
- 2.5 dgr right-thrust
- 1.5 dgr down-thrust

Triangulation Trimming:
- 0 dgr horizontal stab
- 0.5 dgr main wing
- 0.5 to 1.0 dgr right-thrust
- 0.5 to 1.0 dgr down-thrust

I can send you the whole design discussion as an email attachment if you are interested.

OhD

I'm assuming those are all positive numbers? I have the BJ explanatory if that is the design discussion you are referring to. I'd like to hear more about the Triangulation Trimming. What flying characteristic were you trying to improve? I assume the cg was also moved forward? Where did it end up?

I've got 5 flights on mine now and it still needs work. I still don't understand why my measurements indicate the wing is negative. Must be that the anhedral stab doesn't allow accurate measurements, however they are very consistent.

Thanks for the info, Jim

jgg215

Jim,
The two stab tubes of the Nuance are on the stab centerline. Pull one of the stabs out a bit and reference the tubes to zero relative to your table. then the leading edge of the wing should be higher than the trailing edge from the table. According to your numbers, it's probably only a couple of millimeters.
The numbers quoted for triangulation trimming are Bryan's recommended starting point, not necessarily the final triimmed result. Often the final incidence of the wing is a bit higher, like 7 mm.
John

OhD

Thanks John, great idea. I'll will try it and report back. I think this is going to be a very good flying plane when I get it dialed in. I had put it together to have a low investment plane to fly at Sepulveda Basin which is notoriously dangerous for pattern airplanes. Now I see it might be very competitive.

Jim

OhD

It worked and has to be the best way to set the stab to zero. The anti rotation tubes on the wing are also on the centerline so it was a cinch to measure the decalage. And yes the wing was positive to the stab by about .35 degrees. Thanks again for the idea.

Jim O

lc_eiras

Has anyone been tempted to place a T Canalyzer on Nuance?
If so, how many degrees Same as the wing?

lc_eiras

Has anyone been tempted to place a T Canalyzer on Nuance?
If so, how many degrees Same as the wing?

gene55

"For example, if you had 50Amps flowing thru the connector/connection and you measured 100mVDC, the resistance would be 0.1VDC / 50A = 2 milliohms (2 thousandths of an ohm). That is a good number."

Yes, according to OHMS law Voltage / Amps = OHMS.
So, anything other than .1 Volts divided by 50 Amps is a bad number.

Cheers