Just a hunch, but you can verify it easily with an ammeter. The 280 BB motors draw a lot more current than the the bushing can motors - the windings are fewer turns, bigger wire. I suspect you are going over the 10 A limit of the speed control, and it is shutting down to protect itself.
Abel
I have a plane that has never seemed to work very well ever since I purchased it. The parts are as follows: WWII Russian LA-7 (Hobby Lobby)
280 BB Motor 5:1 Gear box (w/ ball bearings) Great Planes C10 ESC (installed Deans conncters) FMA Low Voltage Cut-off Kokam 3 Cell 11.1V 1500mAH battery APC 8x4 Prop FMA Co-PilotThe problem is that not long after hand launching (about 1-3 min) the power in the plane completly shuts off. It takes unplugging the battery and replugging it in to reset something to get the power back on. I have tried different size props by different brands but nothing works. Smaller props have only succeeded in causing the plane to slow drift to the ground from hand launch. The battery is brand new, originally I was using a similar Great Planes battery, but was told that the Kokam had a better energy rating. Is all this normal and if so what are other using for bigger and heavier planes? What will fix this problem?
nothing
David, If you look at the specs, the 280BB is a gawdawful current hog. The run time you're getting is about what to expect if the ESC has a lipo-safe LV cutoff. Bill(oc)
"dhosch" wrote in news:1113689235.575352.188370 @g14g2000cwa.googlegroups.com:
One poster suggested that you may be drawing too much current so the ESC is cutting out to protect itself. Possible, and another possibility is that at full current, the battery's voltage is dropping enough that the ESC thinks the battery is running low. If you have a higher-discharge battery lying around, you can test it with that. Of course, a wattmeter would be the best choice - it'll tell you if you're going over the current limit, too.
I note that the Tower listing for the C10 says that the cutoff is at
3.7V, which is disturbing if true. If it really means 3.7V, then by the time it actually cuts off, a 2 or 3 Lipo battery would be far past the point of permanent damage. If it's 3.7V per cell, well, it's not unusual for the voltage to drop below 3.7 per cell under load, and you'd be getting some inappropriate cutoffs.I'm really not sure what the FMA Low Voltage Cut-Off is doing in this setup - is it supposed to kick in if the C10 doesn't?
The FMA LV cut-off shuts down the motor at 8.4V for a 3cell battery. I tried again this afternoon with a smaller APC 8x3 slow fly prop, without the nose-cone. Pre-flight tests appeared okay (no shut down). Upon hand launching, the plane only flew low and slow until it hit the ground. Its a good thing that I have lots of epoxy lying around. I think this plane has just about had it.
My god. You posted this in about 6 E-zone fora and here as well
The answer has been given you there.
Follow the advice.
That won't kill his avionics. teh BEC is ov erheating -
3s LIPO + three servos - cooling = splat!
Got a problem with that D.H.? You some kind of net nazi or something?
Follow your own advice, get a life!
nothing
Abel and TNP are correct your ESC is the culprit. The Great Planes C10 is also not lipo friendly and adding the FMA seems to be adding to the problem. I think a simple fix would be to buy a lipo friendly ESC with a higher rating.
Mike
nothing
Abel and TNP are correct your ESC is the culprit. The Great Planes C10 is also not lipo friendly and adding the FMA seems to be adding to the problem. I think a simple fix would be to buy a lipo friendly ESC with a higher rating.
Mike
news:1113689235.575352.188370
higher-discharge
wattmeter
I have the C10. Its designed for NiMh/NiCd.....its not lipoly safe. Just adding the FMA so you can use lipos seems like a neat idea, but adds an extra component to go wrong.....perfect example in this post.
Mike
something?
Well Chuck, instead of picking on TNP why don't you give some advice. Lets here it on how to fix "dhosch" problem????
Mike
nothing
"dhosch", I did some "homework " for u Below is Towers info on the C10 ESC ( I could not find my instructions )
This is the C-10 Micro High Frequency Electronic Speed Control w/BEC. When using this speed control with Lithium-Polymer (Li-Po) packs, care must be taken not to over-discharge the packs as the low voltage cut-off on this speed control is not calibrated for Li-Po packs. If Li-Po packs are over-discharged long term loss of capacity may result. To prevent over-discharging, land the plane as soon as there is a noticeable loss of power to the motor.
FEATURES: Extremely compact to minimize weight and simplify installation. For motors up to Speed 400. Uses "Safe Start" system to prevent accidental motor starts by disabling the motor circuitry until the throttle stick is moved to full throttle, then to the OFF position. Factory installed radio, motor and battery connectors. Fully proportional. (Does not have a brake) Battery Eliminator Circuitry provides sufficient current for the receiver and two micro servos. The motor battery powers the receiver and servos. When voltage is reduced to 3.7V, low voltage cut-off circuitry stops the motor while continuing to supply power to the receiver and servos. Built-in thermal shutdown protection turns the motor OFF if the transistors overheat. Reverse-polarity protection. Great for small to medium size electric aircraft. Ultra High Frequency to optimize battery run-time and cool operation. 180 day warranty.
INCLUDES: One C-10 Micro Electronic Speed Control with 2-pin battery and motor connectors, and Futaba J receiver connector pre-installed. Three .01uF capacitors. One 2.75" long, small shrinkwrap tube. One instruction sheet.
REQUIRES: To plug the battery or mini switch into the ESC (female plug), then plug the ESC into the motor (male plug), then plug the Futaba J plug into the throttle channel on the receiver. Soldering capacitors onto the motor. Motor Connector: (if needed for Motor) GPMM3106
SPECS: Length: .83" (21mm) Width: .45" (11.5mm) Height: .26" (6.5mm) Weight: 0.27 ounce (8g) with wires Input Voltage: 5-8 cells Max Rated Current: 12A continuous max BEC Voltage: 5V/1A Low Voltage Cutoff: 3.7V Heatsink: Yes ON Resistance: .0055 Connectors: Futaba J (See comments for male or female JST connector) Switching Frequency: 3kHz For Motors Up To: Speed 400
COMMENTS: If using an Airtronics Z, Hitec S or JR receiver, the plug will have to be modified by removing the polarity tab. For Tamiya type battery connector adapter, use GPMM3108
Not recommended for brushless motors
Bottom line "dhosch": 1. The ESC is not lipo friendly 2. Its designed to operate on 5 to 8 cells ( 6 to 9.6 volts ) and your dumping 11.1 volts into it !! 3. If you are drawing current above the rcomended max plus 11.1 volt of input.....then I would say its overheating. Again I say get a lipo friendly ESC.....about 15A.....and your problems should go away.
Mike
Simple Mike! I think it's been covered. And unlike some here, I don't profess to be an expert in electrics. Nor do I feel a need to repeat what others have said simply to blow my own horn.
Got a problem with that?
| Abel and TNP are correct your ESC is the culprit. The Great Planes | C10 is also not lipo friendly and adding the FMA seems to be adding to | the problem. I think a simple fix would be to buy a lipo friendly ESC | with a higher rating.
You don't _need_ a `lipo-friendly' ESC. If your ESC cuts out motor power at 6 volts, then it's fine for two cell LiPos. If you put on 3 cell LiPos, then it won't cut out for you, but you'll notice a large (and rather sudden) reduction in power shortly before you get to the point where you're discharging the batteries too much. As long as you either 1) watch for that carefully, or 2) carefully time your flights, you can do with another ESC. I'm not saying this is ideal, but it works if you're careful -- I've been doing it on a plane for two years now with no problems. (And if you're not careful, you can ruin your battery.)
Also, I'm surprised that nobody else has mentioned this, but the newest FMA co-pilot
He has the FMA LiPo Low voltage cutoff, not the co-pilot. it weighs 4 grams, cuts off the voltage at the appropriate point. I think whoever said a 3cell Lipo is overheating the ESC has hit it on the head. It's over the rated voltage and probably pulling too many amps too.
PCPhill
| He has the FMA LiPo Low voltage cutoff, not the co-pilot.
No, he has both : > I have a plane that has never seemed to work very well ever since I > purchased it. The parts are as follows: > WWII Russian LA-7 (Hobby Lobby) > 280 BB Motor > 5:1 Gear box (w/ ball bearings) > Great Planes C10 ESC (installed Deans conncters) > FMA Low Voltage Cut-off > Kokam 3 Cell 11.1V 1500mAH battery > APC 8x4 Prop > FMA Co-Pilot
Guilty as charged. .....
whoever said
That would be me Phill.
Mike
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