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Old 08-17-2013, 02:35 AM   #1
GunnyJeeves
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Default Extreme Flight Yak 54 (48") - Hobbyking Motor

Hi,

Grabbed a 48" Yak and Edge 540 from Extreme Flight. (Both planning on 4 cell)

The Edge will be using the Torque motor, Airboss ESC, and Hitek servos.

Figured I would make the Yak using Hobby King Gear.

Servos and ESC are no problem. Motor I am stumped on.

I am thinking this one: http://www.hobbyking.com/hobbyking/s...arehouse_.html

It is 840kv and plan is 12x6 E prop on both. Just wanted you guy's opinion...
Aero drive SK3 - 3548-840 kv. (750 watts vs 700 for the Torque.)


Thanks!
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Old 08-17-2013, 07:52 AM   #2
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Originally Posted by GunnyJeeves View Post
Hi,

Grabbed a 48" Yak and Edge 540 from Extreme Flight. (Both planning on 4 cell)

The Edge will be using the Torque motor, Airboss ESC, and Hitek servos.

Figured I would make the Yak using Hobby King Gear.

Servos and ESC are no problem. Motor I am stumped on.

I am thinking this one: http://www.hobbyking.com/hobbyking/s...arehouse_.html

It is 840kv and plan is 12x6 E prop on both. Just wanted you guy's opinion...
Aero drive SK3 - 3548-840 kv. (750 watts vs 700 for the Torque.)


Thanks!
Hi a 12x6 prop might be to much prop for a 4 cell lipo and the motor you linked to, here is a motor from heads up rc that is close to the motor you linked to, it will be fine with a 3 cell, if you want to use a 12x6 prop and 4 cells , you will need to find a motor with a lower KV to it.

http://www.headsuphobby.com/Power-Up...otor-E-585.htm

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Old 08-17-2013, 08:15 AM   #3
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here is an example, here is a 3561 motor 610 KV that will turn a 12x6 prop with a 4 cell lipo because it has lower KVs

http://www.hobbyking.com/hobbyking/s...ner_610kv.html

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Old 08-17-2013, 08:19 AM   #4
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Here is a Turnigy aerodrive motor that will turn a 12x6 prop with a 4 cell.

http://www.hobbyking.com/hobbyking/s...ner_Motor.html
Overall Rating
Tonino
75 likes
Value Quality 2 thumbs up! Little but very strong en very smooth running motor. No vibrations. With a 13x6 on 4s it ran a little hot. About 60 degrees celcius.

Tested in on a 12x6 blade now at a 4S 4000ma 40-50C lipo: exact 40 amp. About 675 watts. Should be enough. Hoped to run it on 5S, but i don't dare running it on a 12x6 blade.


here is a nice turnigy motor 3548 790 KV that will turn a 12x6 prop on 4 cells

http://www.hobbyking.com/hobbyking/s...ner_Motor.html

verall Rating

vern
6 likes Value Quality Like it? Using on a great planes ugly stik. 4000 4cell battery with 12X6 prop gives me 530 watts at 36 amps. Flys the plane great.

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Old 08-17-2013, 08:44 AM   #5
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what your looking for is thrust and not so much Watts of the motor, Watts is very hard to understand, I can get 900Watts @ 60+ amps out of a 2700KV 28mm inrunner motor with a 6x4 apc prop and a 4 cell lipo, but have very little thrust, or i can use a big motor, low kv get tons of thrust and use little watts and amps, trying to figure out Watts on a planes motor will drive you nuts Calculators might get you some what close, maybe, Thats why I like using Thrust, Now I know what I have, an inexpensive digital fishing scale is great for measuring thrust, hook it up to the tail of the plane and a solid object, set the plane on the ground, and give it throttle and read the thrust pull of the power system. use a Wattmeter and a scale to get the most out of your power system.

Its Thrust not Watts that Moves / Pushes the plane in the Air, you can have 10 different motors and combinations to get 5lbs of thrust, and each one of the 10 motors will have a different Watt Value and Amp Draw, hope that helps, Chellie



http://www.ebay.com/itm/Digital-Hang...item3cc82ad4e2

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Old 08-17-2013, 09:08 AM   #6
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My Favorite web site to find out how much Thrust in oz a Given motor will deliver is Heads Up Rc, Jeff has a lot of motor prop charts with his motors, and its easy to get a powerful power system for your plane using Heads up Motor / Prop / thrust Info. Jeffs Motor Thrust chart applies to other motors of similar size and KV, it will be very close.

http://www.headsuphobby.com/Firepowe...otor-E-650.htm

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Old 08-17-2013, 02:52 PM   #7
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The motor I mentioned is 840 kv, and tolerant of 750 watts. I was comparing it to a torque motor that was 700 watts, and 820kv which is perfect for a 12 x 6 as that's what extreme flight recommends. I think I might be ok.

I was thinking the kv x volts = RPM... And diameter x pitch x RPM = volume of air & speed (thrust). I saw watts as the amount of electrical power required to create and maintain that thrust.

So if an 820 kv @ 700 watts is ok on a 12 x 6 at 45 amps, an 840 kv with 750 watts and 50 amp capability would be also.

Equivalent props to a 12 x 6 would be basically 11 x 7 (lower thrust, higher speed.) and 13 x 5 with higher thrust, lower top speed.

I love the fish weighed idea. It's awesome!
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Old 08-17-2013, 10:39 PM   #8
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Hi here is a neet Thread on Measuring thrust, some people hang their plane with a scale or you can just set it on the ground .

http://www.wattflyer.com/forums/show...measure+thrust


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Old 08-18-2013, 03:11 AM   #9
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Hehe... I grabbed a "Fish Weigher" tonight at Walmart.

Should work good for up to 50 pounds.
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Old 08-18-2013, 03:26 AM   #10
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Originally Posted by GunnyJeeves View Post
Hehe... I grabbed a "Fish Weigher" tonight at Walmart.

Should work good for up to 50 pounds.
They are very handy, i use them to weigh the AUW of my planes too

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Old 08-18-2013, 08:32 AM   #11
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I've played around with those SK3 motors in similar size 3D models.

The nearest equivalent to the recommended Torque 2814T-820 motor is the SK3 3542 800kv. This is in reality exactly the same kv as the Torque and is the same size and weight. It will spin a 12x6 on 4s and give virtually identical power to the recommended Torque .

The SK3 3548 840 kv that you linked to is a little longer and heavier than the recommended Torque but should still fit ok, you should get a little more power using that one on a 12x6 but it will cope perfectly ok with that prop.

But if you want my personal recommendation the motor I'd go with would be the SK3 3548 700kv. This one will allow you to run a 14x7 Xoar prop. Most people find that the bigger prop is better for 3D.
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Old 08-18-2013, 09:53 PM   #12
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Cool. That's good to know. Longer term, I am not sure how these will work out for me, but I am just starting to get where I can pick and understand the needs of ESC / motor / prop combos, so that opens up access to new kits. (As well as Frankenstein options for other planes I have.)

I am basically going to do one exactly as recommended, and one with equivalent HK stuff.
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Old 08-18-2013, 11:14 PM   #13
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Originally Posted by GunnyJeeves View Post
Cool. That's good to know. Longer term, I am not sure how these will work out for me, but I am just starting to get where I can pick and understand the needs of ESC / motor / prop combos, so that opens up access to new kits. (As well as Frankenstein options for other planes I have.)

I am basically going to do one exactly as recommended, and one with equivalent HK stuff.
Hi It Took me over a Year to learn about E Power to get comfortable with it, I am Familiar with electronics, just enough to be Dangerous LOL When i was Learning, I used Heads Up Rc to look up a power system for my Planes, I used the Motor Thrust Charts to find a Suitable motor, prop,lipo size, esc for my planes, and HURC has never let me down, I always try to get a 1 to 1 power system for my planes Its nice to have the power, and I love the way my Planes just Leap up off the ground Take care and have fun, Chellie

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Old 08-18-2013, 11:44 PM   #14
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Originally Posted by GunnyJeeves View Post
The motor I mentioned is 840 kv, and tolerant of 750 watts. I was comparing it to a torque motor that was 700 watts, and 820kv which is perfect for a 12 x 6 as that's what extreme flight recommends. I think I might be ok.
I fully agree that should work well. I think it is a great deal more power than needed however. 3D is about 150w/lb 200w/lb is insane and means you are heavier than needed for good performance.

Originally Posted by GunnyJeeves View Post
Equivalent props to a 12 x 6 would be basically 11 x 7 (lower thrust, higher speed.) and 13 x 5 with higher thrust, lower top speed.
Right - again on 3D types I find that pitch should be about half the length.

Still think that you would be fine with a system that produces 500w or so on that plane. At 700+ watts I think you are just wasting power, have a heavier battery, motor and esc than needed.

It is a diminishing returns thing.

Also - I have always wondered why folks spend so much time on static thrust. It is next to meaningless IMHO. So I will save you the time with fish scales and such. In flight is what matters. I test many props in most airframes until I settle. But I find in the air is what really matters not how hard it tugs on the scale. Spend this time flying, and trying different props till you find one you like - in flight.

Mike
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Old 08-19-2013, 12:28 AM   #15
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FWIW on the same size airframes (EF Edge EXP and EF Laser EXP) I'm running well over 1000W using a motrolfly DM-3615 750kv.

More power is always better in my book providing it doesn't come with excessive weight. 500W on the EF 48" airframes just isnt enough, it is not making the most of the design because speed for high energy 3D is lacking. The stock set up supplied by EF runs just under 700W.

Weight of my motor is about 25-30g heavier than the stock set up but I use a battery at the smaller end of the range (4s 2200mAh) which I get away with due to better efficiency of the larger motor, so flying weight is less than many stock set ups.

The result is 'ample' power:
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ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
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Old 08-19-2013, 12:57 AM   #16
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Originally Posted by JetPlaneFlyer View Post
FWIW on the same size airframes (EF Edge EXP and EF Laser EXP) I'm running well over 1000W using a motrolfly DM-3615 750kv.
I am a fan of the MotroFly motors - but pumping 1k watts through a 123g motor is simply foolish. Even they show 550-625 watts max.

I use 3g per watt as a good number. That means I would rate an average motor of this size at 375 watts. With really good stuff - 4g/watt. That is about 500 watts. Motrofly is good stuff so I would be OK with 4w/g.

Think about it this 123g motor lets say it is 90% efficient (it isn't) it is coping with fending off 100w of heat. I bet that think is SMOKING hot at the end of a run if you use full throttle for any lenght of time. I know you will say you don't need full throttle long - good thing as it won't survive long there. It is likely in the 80-85% efficient range. So you could be using that for 200w of lost power it has to cope with. I don't think that is smart.

Originally Posted by JetPlaneFlyer View Post

More power is always better in my book providing it doesn't come with excessive weight. 500W on the EF 48" airframes just isnt enough, it is not making the most of the design because speed for high energy 3D is lacking. The stock set up supplied by EF runs just under 700W.
500w was plenty for me. IIRC the plane was around 44oz on 3s packs.

To each his own but running a 123g motor at 1k watts is a formula for smoking equipment.
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Old 08-19-2013, 01:31 AM   #17
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Originally Posted by rcers View Post
I fully agree that should work well. I think it is a great deal more power than needed however. 3D is about 150w/lb 200w/lb is insane and means you are heavier than needed for good performance.



Right - again on 3D types I find that pitch should be about half the length.

Still think that you would be fine with a system that produces 500w or so on that plane. At 700+ watts I think you are just wasting power, have a heavier battery, motor and esc than needed.

It is a diminishing returns thing.

Also - I have always wondered why folks spend so much time on static thrust. It is next to meaningless IMHO. So I will save you the time with fish scales and such. In flight is what matters. I test many props in most airframes until I settle. But I find in the air is what really matters not how hard it tugs on the scale. Spend this time flying, and trying different props till you find one you like - in flight.

Mike
That's the kind of info I needed. Never built one up. So far, all had been PNF kits "just add receiver and battery". Just now getting the info and parts up to get practical experience building these things. Basically, I am biting my tongue trying to wait and see how this goes before putting up a 60-64" and a 73".

I don't want to exceed 6 cells, but I don't want any shortage of power either.

I could be wrong, but I doubt I would get a 73 hovering on 6 cells. The point is mute if I can't fix em when I crash.

I can see a difference in the extreme flight models over hobbyking and Nitroplanes equivalents, and as long as I can fix em, it's worth that extra. (I mean dang! Carbon fiber spars the full length of the fuse? = blender @ full throttle without breaking in half!)
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Old 08-19-2013, 06:16 AM   #18
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Originally Posted by rcers View Post
I am a fan of the MotroFly motors - but pumping 1k watts through a 123g motor is simply foolish. Even they show 550-625 watts max.

I use 3g per watt as a good number. That means I would rate an average motor of this size at 375 watts. With really good stuff - 4g/watt. That is about 500 watts. Motrofly is good stuff so I would be OK with 4w/g.
My Motrolfly motor is 195g complete with prop driver and mount, about 175g 'bare'. I'm running it totally within the manufacturer's guidelines. It never gets more than slightly warm, I run a telemetry temp sensor on it. This motor is a very popular choice for 50-52" size models, hundreds in use and I've never heard of anyone running a smaller prop than I'm using (but some run larger) and I've yet to hear of a single failure.

The 3W per gram rule is an ok rule of thumb for sport models, but is very conservative. For example take the Extreme Flight Torque 2814T-820 which is the recommended motor that you get with the 48" EXP's if you take the inclusive option. Run it on the recommended prop and recommended battery it produces 680W, which for a 140g motor works out to around 5W per gram. IMHO because 3D models are very overpowered by normal standards this means you dont use full throttle for more than a few seconds. You can comfortably get away with running a lot higher power from motors than you might do in a sport model, pretty much all 3D models break the 3W per gram rule by a wide margin. Though to be honest my Motrolfly and the Torque will run all day at these power levels as long as they are well cooled.

BTW....Maybe you were thinking of the earlier generation of Extreme Flight models, not the EXP's? The 48" EXP's built with recommended servos and motor come in at 40oz without battery, so you could never get one down to 44oz unless you flew it on a 3s 1300 (despite what it says on the EF web site). EF recomend a 4s 2200 to 2600 battery for these models, a 3s battery doesn't even get mentioned in the manufacturers own spec.
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Old 08-19-2013, 01:48 PM   #19
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Originally Posted by JetPlaneFlyer View Post
My Motrolfly motor is 195g complete with prop driver and mount, about 175g 'bare'. I'm running it totally within the manufacturer's guidelines. It never gets more than slightly warm, I run a telemetry temp sensor on it.
My apologies - I thought you were in the "28" range not the 36. I get it now. They list that as a 900w motor. I would say more like 700-750 in my 4w/g rating.

Try running a HK motor at that rating around 4.5w/g. I have - it smoked even though well within it's rating from HK.

Originally Posted by JetPlaneFlyer View Post
This motor is a very popular choice for 50-52" size models, hundreds in use and I've never heard of anyone running a smaller prop than I'm using (but some run larger) and I've yet to hear of a single failure.
I know that Ben sure does not recommend more than 130g motor for is 48" size - the size the OP is talking about. For a 51-52" I think yoru motor size/weight is about right. Light matters - or you start chasing heavier batteries, esc's and motors to get more power when "light" would have done it in the first place. It is all a careful balance.

No question - if you are happy then no reason to follow the guidelines of the manufacturer.

Originally Posted by JetPlaneFlyer View Post
The 3W per gram rule is an ok rule of thumb for sport models, but is very conservative.
The motor rating has NOTHING to do with the model it is put on. I don't care if it is an airboat, a glider, a sport model, a 3d model an EDF. It is a MOTOR rating, not a "what it is stuck on" rating. It has to deal with how much heat the motor can dissipate pain and simple.

I am not alone with 3w/g. It is a pretty universal standard for "average" brushless motors.

I agree that on Hyperion, Hacker, Scorpion, Neu and likely even Motrofly you can bump that figure to 4w/g. To get this they have to use high quality stuff, the cores, magnets, wire and bearings all need to be up to task. Neu, Scorpion and Huperion do that and yes I would even consider running those at over 4w/g. Neu in the 5w/g is likely safe due to his choice of components that go into his motors.

Just think about facts your 175g motor has to dissipate 150+ watts of heat into the air when running at 1k watts. That is 4 40w soldering irons of heat. YIKES!

Originally Posted by JetPlaneFlyer View Post
For example take the Extreme Flight Torque 2814T-820 which is the recommended motor that you get with the 48" EXP's if you take the inclusive option. Run it on the recommended prop and recommended battery it produces 680W, which for a 140g motor works out to around 5W per gram. IMHO because 3D models are very overpowered by normal standards this means you dont use full throttle for more than a few seconds. You can comfortably get away with running a lot higher power from motors than you might do in a sport model, pretty much all 3D models break the 3W per gram rule by a wide margin. Though to be honest my Motrolfly and the Torque will run all day at these power levels as long as they are well cooled.
I get what you are saying. But it is the folks that are not using it for more than a few seconds that get in trouble. Many just don't have that switch and get caught up in the "watch me go vertical"! excitement.

It is a bit like saying - "watch me stick my hand on this hot stove burner for only 3 seconds"! Yea, right....

Originally Posted by JetPlaneFlyer View Post
BTW....Maybe you were thinking of the earlier generation of Extreme Flight models, not the EXP's? The 48" EXP's built with recommended servos and motor come in at 40oz without battery, so you could never get one down to 44oz unless you flew it on a 3s 1300 (despite what it says on the EF web site). EF recommend a 4s 2200 to 2600 battery for these models, a 3s battery doesn't even get mentioned in the manufacturers own spec.
I am indeed thinking of the 3DHS offering at about 44oz in the 48". When setup with a light 3s setup.

At any rate - it is great we all get to choose how much juice to pass through our stuff.

To the OP - when you are talking about Hobby King equipment, IMHO you are playing with the "cheap" stuff that simply can't handle the 4w/g and 5w/g stuff we are discussing here. That needs to factor in your decision. Take the HK ratings with a grain of salt. I have smoked their motors more than once at their recommendation.

I have also smoked Motrofly motors (a far quality notch above HK) at their recommended numbers too. I also don't believe Great Planes and their Rimfire numbers either.

Mike
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Old 08-19-2013, 06:50 PM   #20
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Yeah, the 3DHS Edge is generally made for a lighter set up than the Extreme Flight models. The EF models, as the name suggests, are perhaps a little more biased toward fast and violent 'extreme aerobatics' rather than being focused solely slow 3D flying. They will do the low and slow stuff some other designs are better suited for that sort of thing.

My set up is definitely a little 'over the top' as far as power is concerned but the model isn't overweight. The motor is a relatively small component in the overall weight build up. I might be carrying an extra 35 grams or so of motor compared to the standard set up but I'm using a battery at the lighter end of the range which more than cancels it out.
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Old 08-19-2013, 06:56 PM   #21
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Agree...

I should point out - our location difference is likely a factor too. I regularly fly in temps over 38C to over 40C (100-105F) here in lovely Texas. It is VERY hard on motors and ESC's even with good cooling.

I suspect you are a tad lighter in the summer there. (22 is a hot summer day right?)

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Old 08-19-2013, 07:03 PM   #22
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We had a heatwave recently, it his about 28C. But yes in the average summer 22C would be a very hot day in these parts, a lot cooler than Texas that's for sure!

Next time I'm complaining about our miserable and cold weather I'll try to remember the 'silver lining' of cool running motors
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Old 08-20-2013, 08:17 PM   #23
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Just a quick update. It looks like my HobbyKing setup will be about 50 grams heavier than the recommended setup, but will produce more power possibly by quite a bit, have more torque on the servos (2.2 kg vs 1.8) and slightly more speed on the servos.

Price difference however will be $260 (motor, esc, servos) vs $75 (motor, esc, servos).

It will be interesting to see if after flying both, which direction I would go for future models.
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Old 08-21-2013, 06:19 AM   #24
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I'm assuming you went for the 3548 size motor if you are 50g heavier?

What servos did you go for?.. You need to be careful that you dont go too big on servos and find that they dont fit the holes.
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Old 08-21-2013, 06:32 PM   #25
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Hehe... They were a whopping $6 and change each... (WOW) but seemed to have the same specs as the Hitec. (So I bucked up and bought 8)

http://www.hobbyking.com/hobbyking/s...arehouse_.html

First time through I opted for the HV option, then luckily I caught it and found these.
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