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Old Mar 19, 2007, 12:32 PM
Wie Ein floh!
109Mechanik's Avatar
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Glenn,

I'm using a 2820/10 aeronaut 10X6 folder, 60amp controller set up with medium timing, enerland 3100 12c lipos all balanced. I'll see how it goes on the 10X6 prop and increase the pitch if necessary
Matt
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Old Mar 19, 2007, 03:57 PM
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The canopy location is the most readily observable out of scale feature. In all the full scale versions, the back part of the canopy extends well past the trailing edge of the wing.

FWIW, I think the model is already a pretty good stand-off scale version of the Mk iX. The vertical fin is way off from the XIV.
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Old Mar 19, 2007, 07:25 PM
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To me the long nose is more noticeable than the departure in the shape of the tailfin. But this sort of thing is so very subjective!

-Flieslikeabeagle
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Old Mar 19, 2007, 10:40 PM
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Quote:
Originally Posted by electroflyer
Hi 109 mechainik,
What is the C rating of your battery packs and are the cells all balanced? Also what type of motor and speed controller are using. My Ripmax is usung a 28/20/10 and a 40 amp speed controller fed by a 4400 3S Lipo. It checked out at 412 watts and was 38 amps at full load using a 12x6 folder.
Glenn
Glenn. I think your use of a 40A ESC is a bit to close to the knuckle in that setup. You should have at least a 45 amp. The ESC can overheat very quickly and will then shut down on you and ruin your whole day.

Cheers. Paddy.
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Old Mar 20, 2007, 12:40 AM
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I've experienced the joy of an overheated ESC in one of my models followed by complete loss of power to the receiver and servos followed by an uncontrolled dive into terra firma.

Paddy's right, it will ruin your whole day.

In my case it was a defective ESC, a previous generation Phoenix 25 with firmware that turned out to be allergic to the low Kv PJS outrunner it was wired to.

I got a note from the mailman today - apparently my package from United Hobbies arrived, but they didn't deliver it because I was at work and not at home. Said package should contain one inexpensive 60 amp opto-coupled brushless ESC and one inexpensive switching BEC. I'm hoping that should I overheat or blow up the ESC, the separate BEC will continue to power the receiver and servos to allow for a safe dead-stick landing.

-Flieslikeabeagle
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Old Mar 20, 2007, 02:48 AM
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SMART MOVE Flying Beagle.

OP.
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Old Mar 20, 2007, 05:09 AM
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Quote:
Originally Posted by flieslikeabeagl
I've experienced the joy of an overheated ESC in one of my models followed by complete loss of power to the receiver and servos followed by an uncontrolled dive into terra firma.

Paddy's right, it will ruin your whole day.

In my case it was a defective ESC, a previous generation Phoenix 25 with firmware that turned out to be allergic to the low Kv PJS outrunner it was wired to.

I got a note from the mailman today - apparently my package from United Hobbies arrived, but they didn't deliver it because I was at work and not at home. Said package should contain one inexpensive 60 amp opto-coupled brushless ESC and one inexpensive switching BEC. I'm hoping that should I overheat or blow up the ESC, the separate BEC will continue to power the receiver and servos to allow for a safe dead-stick landing.

-Flieslikeabeagle
Sorry for your loss and heartache due to your model going in...

I have a thread about one certain 100Amp ESC that I bought from United Hobbies and it did not come with any Instructions and their web site instructed those that purchased this 100Amp to download an instruction sheet from another type of ESC. I did and followed all the instructions carefully and while I was programming the dang thing overheated and heat shrink just melted before my eyes!

As soon as I posted my results I got a PM asking for my telephone number and someone called me saying that the factory made a mistake and that the ESC I ordered was really a 6S Li-POLY maximum ESC OPTO (No BEC) and such that I was using 9S Li-POLYs which explains why the unit overheated?

I shipped the failed unit and United Hobbies Promised to post something conclusive to verify exactly why the unit failed so everyone can see and up to today no one ever has!!!

For what's it worth here's the thread!
http://www.rcgroups.com/forums/showthread.php?t=591615

All I can say is I would not trust any ESC that comes from United Hobbies and especially without any instructions from a reputable company such as two like Castle Creations (US of A)! Jeti is okay as well and as a matter of fact in eBay they do sell Jeti look-a-likes and they even have the gull to say that the Jeti programming cards work on their ESC's!

Whatever you do.....I just hope you don't surpass the maximum limits of that ESC you got from United Hobbies!
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Old Mar 20, 2007, 07:34 AM
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Hi Paddy,

You are right about the 40 amp speed controller and the fine line. However it is well below the rated peak which is 60 amps on this controller. I have also made sure that the speed controller is mounted inside the cooling duct where it will catch good airflow. Apparently in level flight the amps drawn by the motor drop down to approximately 75% of the static amps which would theoretically place the full throttle rating at 28.5 amps. That being said, I will definitely be careful for the first few flights to ensure that it does not crap out prematurely.

Now Paddy, On a totally unrelated topic, do you find that the Cannons on your leading edges snag the grass when landing?

Glenn
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Old Mar 20, 2007, 01:51 PM
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I've read where a lot of people have had problems in which extended partial throttle settings with high pole count outrunners will overheat the ESC. I'm not sure if the problem is limited to CC ESCs.

I haven't heard anything bad about the 60 amp opto United Hobbies ESC. The one that Carlos had was mislabeled. It said it operated on up to 10 cells. But it didn't specify the type of cells. It's pretty clear that any ESC with a linear BEC will not be able to operate on 10 lipo cells. The minimum safe voltage was listed as 4 cells. That tells me that the type of cells is most likely NiCD since at 4 lipo cells you're really pushing a linear BEC.

I believe the 60 amps opto coupled ESC on UH has been verified to work at up to 6s lipos. Apparently, it does require at least 4 lipo cells, though.

Quote:
Originally Posted by flieslikeabeagl
I've experienced the joy of an overheated ESC in one of my models followed by complete loss of power to the receiver and servos followed by an uncontrolled dive into terra firma.

Paddy's right, it will ruin your whole day.

In my case it was a defective ESC, a previous generation Phoenix 25 with firmware that turned out to be allergic to the low Kv PJS outrunner it was wired to.

I got a note from the mailman today - apparently my package from United Hobbies arrived, but they didn't deliver it because I was at work and not at home. Said package should contain one inexpensive 60 amp opto-coupled brushless ESC and one inexpensive switching BEC. I'm hoping that should I overheat or blow up the ESC, the separate BEC will continue to power the receiver and servos to allow for a safe dead-stick landing.

-Flieslikeabeagle
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Old Mar 20, 2007, 02:19 PM
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Paddy, thanks! I hope I never have to test out the hypothesis about the failed ESC!

Thanks for the heads-up, Carlos! The ESC I bought (I picked it up from the post-office this morning) is supposedly rated for 4S - 6S lipo packs. I will be using it with a 4S pack (probably two Apex 2100 mAh 4S 15C packs in parallel to make one 4200 mAh, 4S, 15C pack). Before I bought this ESC I did a little Googling, and I found a few satisfied owners of this particular model of ESC here on RC Groups.

While you underwent some frustration and had to make some noise on RCG before United Hobbies started to pay serious attention to your problems with the ESC they sold you, I am glad to hear they (United Hobbies, that is) eventually did all the right things - they pulled the part off the website, they refunded your money, and they corrected the spec sheet before selling that item again, and they issued a recall to the folks who had already bought the defective item. Nobody could have done more than that (well, they could have gifted you a million bucks, but then they'd be out of business. Thank you, United Hobbies, for stepping forward and dealing with this issue in an honourable way. Your actions encourage me to buy from you again.

As Carlos warned, the ESC came without any programming instructions. However I found them posted on United Hobbies (a downloadable PDF document): https://www.unitedhobbies.com/UNITED...idProduct=2062

The 2.75V/cell lipo cut-off voltage is alarmingly low, so I will take care never to fly till cutoff. Other than that, the programming seems straight forward enough. I seem to remember having used this particular programming scheme on some other brushless ESC in the past (Align, maybe??).

-Flieslikeabeagle
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Last edited by flieslikeabeagl; Mar 21, 2007 at 06:54 PM. Reason: Add some details
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Old Mar 20, 2007, 02:33 PM
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Quote:
Originally Posted by thunder1
I've read where a lot of people have had problems in which extended partial throttle settings with high pole count outrunners will overheat the ESC. I'm not sure if the problem is limited to CC ESCs.
I'm not sure Castle was the only affected manufacturer, however I can say for sure that the only ESC I own that overheated in this fashion was a Castle Creations Phoenix 25.

I tend to overpower my models and then fly them mostly at part throttle, except for those moments when I really do want all the power available (vertical rolling uplines, etc). And several of my models are powered by high pole count outrunners. So if you're right, my flying style is likely to trigger overheating in any ESC's that are prone to this part-throttle-low-Kv-outrunner problem.

So far I have had no troubles with the Hyperion 20A ESC, a cheapo EP Brushless 12 A ESC, a cheap-n-nasty Towerpro 18 A ESC, a couple of Cool Running 10 A ESC's, an Align 35 A ESC, a Hacker 20 A ESC, and a couple of Jeti ESC's in one of my flying buddies planes. And, to be fair to Castle, I have also had no problems with three or four Thunderbird 18's, a Phoenix 35, and a Phoenix 45.
Quote:
Originally Posted by thunder1
I believe the 60 amps opto coupled ESC on UH has been verified to work at up to 6s lipos. Apparently, it does require at least 4 lipo cells, though.
I too read that elsewhere on RCG (i.e. 4S lipo minimum). Interestingly enough, the programming instructions say "*If used 2LIPO you can use the option (select the NiMh/Nicd AUTO)" (sic). Scrambled English aside, the instructions seem to think this ESC will work down to a 2S lipo pack, while the folks who have actually used this ESC say it won't work on less than a 4S lipo pack.

Clearly the documentation isn't exactly up to Astro Flight standards. Fortunately, neither are the prices.

-Flieslikeabeagle
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Old Mar 20, 2007, 02:42 PM
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I think the opto chip needs at least 12 volts or somesuch limitation as that. My CC Phx 45 HV has the same limitation. It may seem to initialize but it could possibly drop out under load.
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Old Mar 23, 2007, 02:45 AM
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I see United Hobbies has a raft of motors in stock now, among them one I have not seen before, the KDA36-12XL: https://www.unitedhobbies.com/UNITED...idProduct=4657
Code:
 KDA36-12XL
 Constant: 770Kv
 Battery: 3/4/5 Cell Lipo
 Operating Current: (3Cell=25A)(4Cell=18A)(5Cell=14A)
 Peak Current: (3Cell=37A)(4Cell=28A)(5Cell=22A)
 Suggested Prop: 14x7
 Shaft Size: 5.0mm x 20mm
 Motor Dimensions: 37.4mm x 48mm    
 Weight: 190g
This one looks interesting to me (for use on the Haikong Spitfire) as the Kv is low enough to use with a 4S lipo pack. It's a bit porky at 190 grams, but then again it is also some $50 (USD) cheaper than the alternatives I was considering, namely the Hacker A30-12XL and Torque 2814-605. Really, the Hacker is no lightweight either at around 179 grams. I doubt a 48" warbird would notice eleven more grams of weight from the much cheaper Keda KDA36-12XL motor. And hey, a motor that's a bit on the heavy side probably means no added lead weights will be necessary to get the Spit to balance in the right place.

I'm sure it is no coincidence that the Hacker A30-12XL was also listed at a Kv of 770 rpm/V initially (I now find it listed as 700 rpm/V from some newer sources). Just as I'm sure it is not a coincidence that the nomenclature "-12XL" occurs in both motors. In other words, I think we potential customers are expected to make the connection that this motor is intended to be a copy of the Hacker A30-12XL.

By the way, this motor is a big sister to the other inexpensive Keda motor that performed so impressively for the Bungymania.com guys (and for Thunder1 on this thread). Hopefully big sister has the same high efficiency and unexpectedly high quality as little sister turned out to have.

Anyhoo, at under $32 USD, I thought some of you might be interested. I know I am.

It may be worth mentioning that a Hacker A30-12XL and Castle Creations Phoenix 45 combo from North East Sailplanes costs $160 USD. Meantime the 60A ESC I bought from United Hobbies cost $27.54 and this Keda motor costs $31.20, for a total of $58.74 or roughly one hundred bucks less than the "name brand" combo.

Not to start any more "quality costs more!" "No it doesn't!" flamefests, but that is a mighty big price difference, big enough that I would forgive some loss of quality for it.

-Flieslikeabeagle

P.S. United Hobbies lists one other outrunner with a comparably low Kv and of about the same size and weight, the HXT42-50-700 HXT. Unfortunately, this motor is listed as having a truly awful no-load current of 3.4 amps. Assuming this is not a typo, this means the motor would suck nearly 50 watts from a 4S lipo pack even when under no load at all.

There are some very positive reviews for the motor on the UH site, including one claiming a motor efficiency measured at over 80% using a Hyperion Emeter. I'm not sure what to make of that claim, unless the 3.4A no-load current is a typo. (3.4 amps is a LOT, and would indicate very low-grade magnetic material in the stator.)
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Old Mar 23, 2007, 10:35 AM
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Mine goes like stink on the KD 36-12L and 3s lipos. The KD 36-12XL and 4s lipos would probably exceed warp 5;-) And it's a drop in fit!

I'm in love with these KDA motors, especially their price.

Gotta love the power.
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Old Mar 23, 2007, 10:49 AM
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It's pretty similar in spec to the Hextronic motor I bought as well (as I think Thunder pointed out before). I wonder how the KDA and hextronic compare in efficiency, etc.

Edit:

I think I found at least one answer to my own question on Bungymania. It looks like the KDA is 96% max efficiency and the Hextronic is 90% max efficiency.

Steve
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