Wingdinger2

Hi guys, I'm trying to figure out what happened to me tonight. I have a Phase 3 U-2 EDF foamy, which has about 4 flights on it since coming into my possession. Tonight I flew it twice, first flight with no incidents whatsoever, taking it to my visual limits, which is a decent range. The second flight didn't go so well. I took off, started climbing out, and about 10 seconds into the flight it quit responding to the controls. It hooked a hard left, and started looping. It managed about two loops before meeting the trees. I managed to get it down and am at a loss. Surprisingly the plane survived with not much more than battle scars, and I tested everything once I got it back. I suspected either a lockout or a servo failure, but all the servos (3 Emax micro's) are working perfectly. The ESC and motor work perfectly, although the fan unit was destroyed in the crash. Both batteries were freshly charged. I'm using a 2.4 Ghz Optic 6 with an Optima 6 Lite. What could possibly have caused it? The only difference between the two flights was that the belly of the plane was wet from the first landing on wet grass. The electronics were not at all damp however, being in the cockpit, and I checked the duct for moisture before launching it the second time. Could moisture somehow be the culprit here? Can that cause RF interference? The antenna is tucked under the cockpit in a crack beside the nacelle. (see photos) Both flights, the plane was carrying a small keychain camera mounted under the wing. I haven't been able to find it yet, but will try again tomorrow. I've used the camera numerous times and have never had an issue, I don't believe it's related to that. I also fly a glow heli with this radio, and haven't had any issues yet. Any clues?

thailazer

Sounds like the plane servos stayed at a position they were put in, so no erratic behavior. I would first suspect that somehow the receiver lost is power source. Check all your connections to make sure they are 100% solid, and then find some way to evaluate your ESC. Your engine had good power but the receiver and servos might have been out to lunch. These are frustrating and I wish you luck in finding the root cause.

Wingdinger2

The funny thing is, I was climbing gently, with wings level when it happened. As I mentioned earlier, it banked hard left, seemingly max deflection, and then started looping as well, seemingly with max up elevator. It definitely wasn't maintaining the servo positions I was commanding. When the RX loses TX signal, the servos freeze right where they were, according to my tests. Would losing RX power cause such a radically different scenario? How would I check the ESC?

thailazer

You are right in that usually when a receiver loses power, the servos stay right there. To check the ESC, put a voltmeter on the RX output with everything running and try squeezing and lightly bending the ESC in case it has poor connections. Seems unlikely in your case though. Another thing it could be is a high power transmitter running nearby that just overloaded your receiver for a bit.

A.T.

Very typical of an overloaded BEC, and /or a battery failing under load, especially with cheap servo and extra equipmwent, refer:
. Electronic Speed Control - Why BEC and LVC cause most EP RX problems, posts #2 & #3.
. Servo - FAQ : Which servo to buy - Peak Servo Current Test Results. ***]

Much more information available under sub sections
"Battery Care, Performance & DIY Battery Packs."
"ESC & BEC - Setup to prevent majority of all RF Problems, Brownouts & Crashes"
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
"Servo - Alterations, Calculators, Databases, Leads, Repairs, Convert to an ESC or winch & FAQ."
below
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model & RC FAQ Web Links

Alan T.

Wingdinger2

Being overpowered by interference is definitely not a pleasing prospect, but I would imagine it would have happened before if that's the case. Is it possible that voltage sags from the ESC could cause a brownout? I was at full throttle, which means max amps, do ESC's ever struggle to maintain RX power output? But again, this wasn't it's first flight, and I had flown it previously with batteries that weren't topped off. Am I correct that these receivers are pretty picky about their power? I'm wondering if I should use the SPC connector on the RX for relatively fail safe power.

A.T.

"Being overpowered by interference is definitely not a pleasing prospect,"
Not interference, simply the ESC/BEC unable to handle the loads, overheating and shutting down and cutting power to other units.

NO Brownout indicated, but SPCshould always be used for EPModels:

. Optima Transceiver (RX) - SPC connection & Lead FAQ for EP & GP models - with schematics and Photos.
...Low & High Voltage setup,
. Optima Transceiver (RX) - EP Models Use SPC Port for RX Power Supply (BEC only is unreliable) & correct Battery Telemetry.

Please read the previous links provided, as
"I was at full throttle, which means max amps, do ESC's ever struggle to maintain RX power output?"
Yes, report evidenced that BEC was overheating - please read carefully all the information provided in the links quoted previous post
in order a good understanding of why BEC fail is learnt.
With more than three servo in an EP model, a UBEC(aka SBEC or switchmode regulator) of 5A or 10A should be used.
(refer schematic attached SPConnection link above.)

Alan T.
Alan's Hobby, Model & RC FAQ Web Links

JIMF14D

Did you have failsafe set to trimmed flight and zero power?

Wingdinger2

Thanks! It's starting to look like that might have been my problem, power issues to the RX. So, according to what I'm reading, I should be using the SPC, and a standalone BEC, all wired to the same battery as the ESC, or at the very least, a high quality, high power standalone BEC. I noticed in the articles that when using the SPC, it should be powered up before power is fed to the servo bus. If everything is wired together, how do you do that? Do BEC's have switches on them? That's the only way I can think of. Any recommendations on good BEC's?

A.T.

" noticed in the articles that when using the SPC, it should be powered up before power is fed to the servo bus.
If everything is wired together, how do you do that?"
No problem since introduction of recent firmware which negated the boot up delay.
Receiver side now gets full power at same tinme as servo bus.
A note to that effect:
"[This does not apply to Optima with firmware above 1.01 and where SPC lead is connected to ESC plug. Both power up at same time]"
was added, perhaps missed a page so will check all and amend.

Alan T.

Later found one missed instance and above now added, Tks. A.T.

Wingdinger2

Ok, thanks. I missed that.