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Old Oct 20, 2011, 01:50 AM
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There is limiting temperature of transistor in operation. In our case it is mostly +150C. But when you measure the body of the ESC(BEC) you are measuring the heat sink so it is lower then the one of the transistor by ... say 25%+- So we see that it is somewhere +112C. So it is easy to see that T=+ 80-90C would be safe.
When the ESC is outside I believe you can even play with 25A ESC at 30-35A load if it is not for extended period of time. I did try that.

PROCEED AT YOUR OWN RISC.
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Old Oct 20, 2011, 02:14 AM
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150C?!? Considering water boils at 100C (212F) that seems awfully hot! Even 112C (~237F) seems pretty high. I've routinely taken temperatures (with infrared no-contact thermometer) on my 20A sink-less ESC in the low 120F (~49C) range. It's therefore hard to believe it ever got anywhere near your figures, tho it did get hot enough to melt the clear heat-shrink cover running the 6x4E prop.

It'l be interesting to see what kind've temps I get in my testing, and how it'll compare to a 30A upgrade.
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Old Oct 20, 2011, 04:13 AM
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Originally Posted by Gunnycig View Post
Hello,

This is my 4th FPV plane flight and it seems there is a problem in the stock bixler motor or exceed 40 amp esc Im running. There is a high pitched squeal at random times. The attached link is from a 808 cam I had attached since its better quality than the cam I fly with. I lost my signal at 2 miles and when the Eagle Tree RTH kicked in I got the noise. My amps also jumped from about 7 to 18-20 during the noise. This has happened on 2 previous flights and the RTH also engaged then. Im not sure if this is a motor, esc, osd pro, or other problem. Any suggestions would be greatly appreciated.

http://www.youtube.com/watch?v=Gxa8aZS-Iyk
Nice video and stunning location. Where was the filming done?
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Old Oct 20, 2011, 05:54 AM
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Россия, Калужская область, город Калуга
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Originally Posted by StarHopper44 View Post
150C?!?
Have a look here:
http://www.fairchildsemi.com/ds/2N/2N3904.pdf
These are tiny things say BUX32 which would be closer to our appliances has +200C.
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Old Oct 20, 2011, 06:08 AM
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United States, NY, Wolcott
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IMHO if the device is hot to your touch, it is too hot. Comfortable water temperatures for taking a shower is 115F +/- so 120-130F would be my max. Run them hotter if you want but that's my procedure.
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Old Oct 20, 2011, 07:59 AM
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Originally Posted by ozair View Post
Great job HFB. This data is very usefull especially the ESC temps, with and without the BEC. Servo currents are handy to know as well, were these the stock servos or the HXT 900's?

Was this data acquired with the Eagletree V4 same unit at HK for about $48-?
I actually used a borrowed V3 I had lying around while I waited for my V4 since I had sold my old V3. Data should be the same regardless of V3 or V4 though.
Servo currents were actually a combination of stock in the ailerons (couldn't get the foam strips off over the wiring) and HXT 900's on the rudder/elevator.
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Old Oct 20, 2011, 08:04 AM
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Originally Posted by StarHopper44 View Post
Wow - I'm in candyland!!

To Ozzy and HFB:
What were the LiPo pack(s) you each used, and their normal & burst ('C') ratings? Might that have affected the numbers??

To HFB:
Were your full-throttle readings made during straight & level flights, ie no climbing, or turns where the loading (or unloading, depending on direction of turn) on the prop would've had some effect?
[[Addendum: Haven't 'blown up' your thumbnails & read, yet....just reading off the board here.]]

Or even, upwind vs downwind legs? That's one thing I'm interested in testing with my EagleTree when it arrives. Planning on setting 'er to steady half-throttle, & just flying some identical rectangle patterns to study that. And seems that's one area where bench-testing can provide some 'steadier' comparative data.
My packs were both 20C but if you look at the voltages for the two of us, they are typically the same. At some maximums, I'm at 12V, he's at 11.9V but most of the time, we're both around 11.8V.

Full throttle flights were typically flat and level, almost no wind at the time but either way, I was flying ovals so one way, it would be headwind and the other tailwind. I noticed the maximum power cam right as I went full throttle and stabilized after that.

As to fuselage temperature, I put that in there for people that make the NACA ducts. I was trying to figure out if it's really necessary at all. I suppose if the ESC temps get too high, then having the moving air may help. I just took it as another data point. Hence, the fuselage and ambient air temperature to get an idea of what kind of air you would have pass through if you had ducts.
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Old Oct 20, 2011, 08:17 AM
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Quote:
Originally Posted by ua3xds View Post
There is limiting temperature of transistor in operation. In our case it is mostly +150C. But when you measure the body of the ESC(BEC) you are measuring the heat sink so it is lower then the one of the transistor by ... say 25%+- So we see that it is somewhere +112C. So it is easy to see that T=+ 80-90C would be safe.
When the ESC is outside I believe you can even play with 25A ESC at 30-35A load if it is not for extended period of time. I did try that.

PROCEED AT YOUR OWN RISC.
Your last statement is false. The way the brushless ESC works is that is pulses at full current for a set time. By varying the duty cycle, you get your average current that's delivered to the motor. So if your motor is a 20A motor pulling 20A and you have a 25A ESC, each pulse delivers 25A but only for 80% of the time, giving you an average 20A. You'll only measure 20A even though it pulses at 25A. If you try to pull 30-35A out of a 25A ESC, it'll try to deliver 30-35A, whatever the motor asks for, so it'll be full on and will eventually blow your ESC.
Don't do it, even if it's worked for you before. You're just asking for trouble.
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Old Oct 20, 2011, 08:49 AM
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Originally Posted by healthyfatboy View Post
You're just asking for trouble.
As you can see I started my last statement with "I believe you can" which does not mean "I guarantee you can". And choosing between “waiting for a month for the delivery” and “asking for trouble” I vote for the second. When it gets burned then there is no choice. Worked fine for me so far. Although it just the motor’s specs say 30A, 2S-4S. Not the measurements. So 25 ECS stays cold with 3S. It may not draw as mach with it.
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Old Oct 20, 2011, 09:42 AM
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Originally Posted by ozair View Post
I now have some reading to do, thanks again AJ.
Oops. I forgot to put the link on the "EXCELLENT" video on gyros.
AJ
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Old Oct 20, 2011, 11:03 AM
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Oh...@HFB; forgot to ask:
Does the EagleTree (Ver 4) log multiple flights, or do ya gotta dump data between each flight?
If yes, about how many &/or duration is its capacity?
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Old Oct 20, 2011, 11:29 AM
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Originally Posted by healthyfatboy View Post
...As to fuselage temperature, I put that in there for people that make the NACA ducts. I was trying to figure out if it's really necessary at all. I suppose if the ESC temps get too high, then having the moving air may help. I just took it as another data point. Hence, the fuselage and ambient air temperature to get an idea of what kind of air you would have pass through if you had ducts.
So the fuse-temp was just the sensor hanging free inside....not like, receptor taped to the fuse wall or something, right?

And I can tell you the spoon-ducts (in on top nose, exit on fuse just aft of fan) DO work! Post-landing reads on the stilted ESC were a good 20-30* less than before ducts were made....but I can't relate that (before & after) to how hard the motor was ran for final several seconds of flight - no definitive 'before' figures taken.

I ordered 2 temp sensors with my ET so I can take ESC & initially, motor reads which I plan to slip over to the LiPo. Would've gone ahead with 3 but figured the LiPo reads would show a pretty tight range of numbers that won't change much overall, so kinda felt a 3rd would be wasted money. Knowing me, I'll prolly wind up with the 3rd. And a spare. Or two. Or.... *LOL*

(It's a sickness.)
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Old Oct 20, 2011, 11:45 AM
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Originally Posted by ajbaker View Post
...on the "EXCELLENT" video on gyros.
AJ
You're easy to please.
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Old Oct 20, 2011, 11:51 AM
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Originally Posted by StarHopper44 View Post
So the fuse-temp was just the sensor hanging free inside....not like, receptor taped to the fuse wall or something, right?

And I can tell you the spoon-ducts (in on top nose, exit on fuse just aft of fan) DO work! Post-landing reads on the stilted ESC were a good 20-30* less than before ducts were made....but I can't relate that (before & after) to how hard the motor was ran for final several seconds of flight - no definitive 'before' figures taken.

I ordered 2 temp sensors with my ET so I can take ESC & initially, motor reads which I plan to slip over to the LiPo. Would've gone ahead with 3 but figured the LiPo reads would show a pretty tight range of numbers that won't change much overall, so kinda felt a 3rd would be wasted money. Knowing me, I'll prolly wind up with the 3rd. And a spare. Or two. Or.... *LOL*

(It's a sickness.)
You can record any number of flights without having the unload the data but it depends on your sampling rate and how long you fly each time. I had probably 30 minutes or so of data on it and I believe it only took up a quarter or half the memory, I honestly can't remember, but it won't matter for you. The V4 has even more memory so no problems there.
I just let the temp sensor hang out in the fuse. I didn't want to tape anything in.
I have no doubt the ducts would help but I was trying to get an idea of it I needed to do it or not. Flying in the winter here, it may be better for me to keep it closed off so any heat from the ESC helps keep it warm as the LiPo can sag at cold temperatures. We'll see. I'll just play with it.
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Old Oct 20, 2011, 12:02 PM
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USA, NY, Endicott
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My SkyS Build Log

OK guys, I completed about 95% of my SkyS build log. I have it on my newly created blog. (Just click on Papo_60 to the left.) One would almost think I new what I was doing.... One thing I did is to creat several blog entries so comments to any particular build area would be confined to that post??? If that makes sense..

Anyway, if interested, please take a look & make any comments in the blog area. Especially if you find any corrections that need to be made &/or additions that you think would be helpful to people doing a similar build.

I plan to add a couple more pictures later today of the coupleted assembly & also complete the write up for the bind & range test.... But other than that I believe this build log is complete.. Hope you enjoy & let me know what you think.

Again though, any corrections or suggestions you come across, please use the comment section in the Blog. Don't want to clutter up this forum with such stuff.... TIA
Ron
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