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Old Aug 11, 2010, 08:57 PM
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Garrett, I fly at Chatfield, I'm at 5400' altitude here, so I know what you mean.
Certain Turnigy motors do seem to be a bit power hungry, but that all depends on what prop you run, how you fly, throttle management, etc.
I tend to overpower everything I have, I would rather have too much than not enough, but I also like to keep the wing loading as light as possible.

The SK 35-48 motors are pretty decent, I doubt you would be disappointed.
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Old Aug 11, 2010, 09:06 PM
Garret H's Avatar
USA, CO, Fort Collins
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Ok, thanks for letting me know. I am the president of the Rocky Mountain Modeleers up here in Fort Collins -- our vice president came from your club.

I run two SK series 35-36 motors and they seem to work great -- one is in an electric club trainer and gives great power and good run time. But, I bought these motors quite a while back -- I have held off buying any more because of things I have heard about the recent ones. The top (most recent) reviews on the product page are quite poor. People are complaining about bad bearings, magnets coming loose, and even some not working right out of the box:

http://www.hobbyking.com/hobbyking/s...8_900Kv_/_770W

I dunno -- maybe these are just isolated instances, but it just seems like the last few production runs of these motors have been poor...

Garret
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Old Aug 11, 2010, 09:11 PM
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Then again, that SK motor is considerably lighter than the 42-50 Turnigy and gives out 50 more watts! Hmm....

Interestingly, the EF Power 32 is technically a 42-50 (going by size) and is actually heavier than the Turnigy model...

Garret
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Last edited by Garret H; Aug 11, 2010 at 11:15 PM.
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Old Aug 12, 2010, 07:40 AM
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What I normally do is when I first get them out of the box, I add a drop or two of household oil in the bearings and work it in a bit. It does seem the lubricant is a bit lacking in the bearings, but I haven't had but one bearing failure since I started oiling them.

I can't imagine your .25 sized stick will weigh much more than 3 1/2-4 lbs AUW, the SK 35-48-900 or 1100 would give you nearly 200 Watts/lb, it would be just fine on 4S too. You could most likely spin a 12X6E prop with the 900kv version no problem, would be a beast.
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Old Aug 12, 2010, 09:17 AM
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Hmmm....that is sounding pretty good. I may have to go there....

What would you suggest for a battery? This plane is odd in that I have read of all kinds of setups -- some people are using 4200's, and some are using 2600's....

What do you think of this one? I have been wanting to try some of these Nano-tech packs, and this one is at a good price:

http://www.hobbyking.com/hobbyking/s...dproduct=11920

It seems when you step up to even a 3300 or 3600 there is a considerable weight jump...

Garret
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Old Aug 12, 2010, 06:48 PM
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Garrett, if you ran it at 770 Watts, on 4S you would be drawing between 36-42 amps max, depending on the charge of the battery. So, taking that into consideration, the nano-Tech batteries probably aren't needed. If you ran a 3600 20C pack, you should have 72 amps continuous available.
I would go with the lighter Turnigy or Flightmax packs, 3600-4000ma 4S. Should be plenty of current capacity.
Be sure to run a high enough capacity ESC, I would run a Plush 60.
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Old Aug 12, 2010, 07:18 PM
Garret H's Avatar
USA, CO, Fort Collins
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Quote:
Originally Posted by speedy72vega View Post
Garrett, if you ran it at 770 Watts, on 4S you would be drawing between 36-42 amps max, depending on the charge of the battery. So, taking that into consideration, the nano-Tech batteries probably aren't needed. If you ran a 3600 20C pack, you should have 72 amps continuous available.
I would go with the lighter Turnigy or Flightmax packs, 3600-4000ma 4S. Should be plenty of current capacity.
Be sure to run a high enough capacity ESC, I would run a Plush 60.
OK, thanks -- yep, I ordered a Sentry 60A...the Plush was out of stock and not much less in price. The only reason I asked about the Nano-tech was because I have yet to test one. And, it was relatively the same price -- but, I sort of figured 3000mah would not be quite enough. I will go take a look at some larger ones...

Thanks so much for your help,
Garret
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Old Aug 12, 2010, 09:29 PM
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No prob bud
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Old Aug 12, 2010, 09:30 PM
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Maybe someday i'll get up to your part of town with a plane or two and do some flying :0
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Old Aug 12, 2010, 10:11 PM
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Certainly! Stop by any time. Feel free to send me an email and I can meet you there...

Here's the link to our website: http://www.modeleers.org

Garret
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Old Aug 12, 2010, 11:46 PM
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Quote:
Originally Posted by speedy72vega View Post
Garrett, if you ran it at 770 Watts, on 4S you would be drawing between 36-42 amps max, depending on the charge of the battery. So, taking that into consideration, the nano-Tech batteries probably aren't needed. If you ran a 3600 20C pack, you should have 72 amps continuous available.
I would go with the lighter Turnigy or Flightmax packs, 3600-4000ma 4S. Should be plenty of current capacity.
Be sure to run a high enough capacity ESC, I would run a Plush 60.
One more question -- would a 20c pack really be sufficient for my application? Or should I go with atleast a 30c? The reason I ask is because of the price jump -- 30c packs are much as $10-$15 more as the same size 20c batt.

Garret
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Old Aug 13, 2010, 07:56 AM
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If you run a 3600ma pack that's 20C, that's 72 Amps constant (theoretically). If you're only pushing 36-42 amps, you're well within the capacity of the battery.
The only thing you might get from a higher C rating is possibly a more stable voltage under load.
A 4000ma 20C pack should be able to deliver 80 Amps constant, so you can see that any higher of a C rating would probably not be too noticeable as far as performance.

Now on the other hand, if you were running a setup that drew 60-70 Amps, a higher C rating would most likely be a benefit, resulting in more stable voltage.
When the voltage drops off under load, performance suffers due to the lower RPM of the prop, a result of lower voltage. The Kv rating of the motor means RPM/Volt, so the lower the voltage, the lower the RPM.

I myself would stick with around a 4000ma 20C pack, it should be just fine.

In my Ultra Stick 60, i'm runnung a 42-50-650 SK motor, spinning a 12X8E prop on 6S, and I get almost 1150 Watts, at nearly a 70 Amp max draw. The packs I run are either the Turnigy or Flightmax 6S 5000ma 20C packs, and they work great. I have 3 planes that all use these packs, the Stick, an Extra 330L .90 size, with a Power 60 motor, spinning a 15X10E prop, and also my Hangar-9 P-47 with a Turnigy 50-65B-350 motor, spinning a 16X10E prop. I get a 9 minute flight out of this one, and there's still 1/3 of the pack left afterwards.
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Old Aug 13, 2010, 10:00 AM
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OK, good to know. Would you use an external BEC on this setup? I am inclined to do without -- a friend of mine has the 25e Beaver and runs 6 MN48 servos without a BEC (Plush 60A ESC) and does not have any problems. And he flies Spektrum! My setup will only have 4 servos (probably 81's or 225's) -- I think I should be OK, right? -- all my other larger electrics with 4x 65's don't have any issues. I don't fly TOO aggressively.... BTW, I use Airtronics 2.4 -- much lower minimum input voltage.

Thanks!
Garret
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Old Aug 13, 2010, 10:05 AM
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I guess it is between one of these two then (the Rhinos are out as they are quite heavy compared to the others):

http://www.hobbyking.com/hobbyking/s...idProduct=9463

http://www.hobbyking.com/hobbyking/s...idProduct=9364

I wonder why the Turnigy is so much heavier? I guess the lighter weight Zippy is worth the extra money...

Garret
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Old Aug 13, 2010, 11:35 AM
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I've had pretty good luck with both Zippy and Turnigy, can't beat them for the price.
Turnigy is now made in-house by Hobby King, and they claim the QC is much better, but I think it's a toss up between the two. I usually make my decision on which one to buy based on which one is in stock.
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