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Old 03-12-2011, 04:49 PM   #1
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Default Not Enough Power - - -

Here's my set-up.

HobbyPartz MonsterPower 60, 400kv.
HobbyWing 60 AMP ESC
HobbyKing 5S, 5,000 mAh Nano-Tech Battery
APC 14x10 Electric prop.

My results?
580 Watts at 32 AMPS.

I ran through the programming of the ESC and reset the timing to 15 degrees (which was supposed to be the default) and the results didn't change. I tried two different batteries.

I think this combo ought to be producing twice the wattage as I'm getting.

Any ideas what's wrong?


...The Bum
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Old 03-12-2011, 05:09 PM   #2
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I run the SK5055/580 with a 15X8 prop 1237watt @ 66amp. Have also tested MAS 14X8X3 1377watt @ 77amp MAS 13X8X3 1100watt @ 59amp. All with 5S5000 & 80amp ESC.

First thing I would do is try a different prop.

Kevin
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Old 03-12-2011, 05:28 PM   #3
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Originally Posted by BEAR-AvHistory View Post
I run the SK5055/580 with a 15X8 prop 1237watt @ 66amp. Have also tested MAS 14X8X3 1377watt @ 77amp MAS 13X8X3 1100watt @ 59amp. All with 5S5000 & 80amp ESC.

First thing I would do is try a different prop.
I tried a 13x6.5 which yielded 340 Watts at 18 Amps.

A 20x8 gave me 1100 Watts at 62 Amps.

I think I need more prop. I'll go buy a 15x8 and try that.

...The Bum
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Old 03-12-2011, 06:08 PM   #4
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You can increase voltage or prop, but 400kV is very low for 5s voltage. That is your issue.
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Old 03-12-2011, 08:15 PM   #5
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You're not going to get anywhere near twice the power on a 5S battery....that would need well over 60A and that motor is only specified for 40A continuous.

As rcers says another cell or two is what you need.

Steve
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Old 03-12-2011, 08:43 PM   #6
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Originally Posted by rcers View Post
You can increase voltage or prop, but 480kV is very low for 5s voltage. That is your issue.

Looks like a 6S and a 15x8 is what I need.

Thanks guys... The Bum
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Old 03-12-2011, 10:27 PM   #7
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Originally Posted by Saddlebum View Post
Here's my set-up.

HobbyPartz MonsterPower 60, 400kv.
HobbyWing 60 AMP ESC
HobbyKing 5S, 5,000 mAh Nano-Tech Battery
APC 14x10 Electric prop.

My results?
580 Watts at 32 AMPS.

I ran through the programming of the ESC and reset the timing to 15 degrees (which was supposed to be the default) and the results didn't change. I tried two different batteries.

I think this combo ought to be producing twice the wattage as I'm getting.

Any ideas what's wrong?


...The Bum
I ran the Monster Power 60 numbers through www.motocalc.com. The Monster numbers are 400Kv, 1200W, 0.06 ohms, 2.7 Amps idle, 40 amps continuous, 60 amps burst, 14.8 ounces weight.

Motocalc indicates running this motor on 5 Lipos and a 14X10 prop will give you about 600 watts and about 6200 RPM. Its efficiency is about 78% at those power levels. Push it much over 600 watts or so, and that motor is going to run hot.

Compare that to a Hacker A50-12S motor, similar size motor. Its winding resistance is 0.012 ohms, 1/5 that of the Monster Power 60. That translates directly into heat, and low efficiency on the Monster motor.

Motocalc predicts the Hacker will turn a 14X10 prop at about 8100 RPM on a 5 Cell Lipo, pulling around 60 Amps out of the battery. That's about 1200 Watts. I've got two of these motors, they will do what they say they will. They both turn a 14X10 at about 7950 RPM. One of them is three years old and has 200+ flights on it. The second was purchased two years ago with about 100 flights, and has identical performance as the first one.
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Old 03-13-2011, 12:01 AM   #8
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What happens in MotoCalc on a 6S battery, Kyle?

(Thanks for doing this, I appreciate it.)
...The Bum
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Old 03-13-2011, 01:46 AM   #9
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Originally Posted by Saddlebum View Post
What happens in MotoCalc on a 6S battery, Kyle?

(Thanks for doing this, I appreciate it.)
...The Bum
Hi
Take a look at the attached files, one of the Hacker, the other of the Monster motors. These files shows what happens when you run props from 12X8 to 14X10 in Motocalc.

Note the motor efficiency indicated on both motors, and how many watts are lost in the motor in the "Loss" column. The Hacker is quite comfortable running 60 amps on the ground with proper cooling. (From personal experience with a LOT of flights) If you configure the Hacker by bolting the prop to the rotating housing, and just put a prop nut on the motor, the air blast through the motor keeps its temperature to about 15 degrees above ambient as measured by a thermocouple thermometer. Looks like a 13X8 prop would be good for the Hacker, that will turn it around 10,000 RPM. That shows an efficiency of 89%, not to bad. If you want more torque, go to a A50-16S which will turn a 16X12 prop on 5 Lipos. (Also have this set up.)

Motocalc suggests running 40 Amps through the Monster motor will result in the motor running some 300F. Sixty amps through it could burn it up. Looks like a 14X8 would be a good prop for this motor, that it will turn at about 7400 RPM, at about 800 watts. The MotGB motor efficiency drops to about 78% though, not to good.

DennyV


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Old 03-13-2011, 06:48 PM   #10
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Originally Posted by kyleservicetech View Post
Hi
Take a look at the attached files, one of the Hacker, the other of the Monster motors. These files shows what happens when you run props from 12X8 to 14X10 in Motocalc.

Note the motor efficiency indicated on both motors, and how many watts are lost in the motor in the "Loss" column. The Hacker is quite comfortable running 60 amps on the ground with proper cooling. (From personal experience with a LOT of flights) If you configure the Hacker by bolting the prop to the rotating housing, and just put a prop nut on the motor, the air blast through the motor keeps its temperature to about 15 degrees above ambient as measured by a thermocouple thermometer. Looks like a 13X8 prop would be good for the Hacker, that will turn it around 10,000 RPM. That shows an efficiency of 89%, not to bad. If you want more torque, go to a A50-16S which will turn a 16X12 prop on 5 Lipos. (Also have this set up.)

Motocalc suggests running 40 Amps through the Monster motor will result in the motor running some 300F. Sixty amps through it could burn it up. Looks like a 14X8 would be a good prop for this motor, that it will turn at about 7400 RPM, at about 800 watts. The MotGB motor efficiency drops to about 78% though, not to good.

DennyV
Hi Denny;

Well... long story short, I'm going to dump the Monster 60 and buy a Hacker. You have educated me enough to understand that I have to learn about motor "efficiency" as well as kv ratings to understand what I am buying.

WOW! So much to learn!

The Hacker website confuses the heck out of me. It seems there are multiple motors that appear to be the same size, but have different specifications. What is critically missing is any reference as to which motors might be appropriate for different applications.

You mentioned the A50-16S and the A50-12S. Both seem to be made for 4S to 6S batteries with the 16S having more torque.

Would you be so kind as to explain what the "12" and "16" mean as well as the "S"? There seem to be 10's, 12's, 14's and 16's as well as "S" and "L" motors. VERY confusing.

Lastly, where do you guys buy your Hackers?

The Electric Motor Mystery is starting to become clearer!

Thanks
...The Bum
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Old 03-13-2011, 07:34 PM   #11
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S = short, L = Long can....sometimes things are straightforward .

The 12 and 16 are number of turns.

Generally more turns and/or longer can = lower Kv / more torque so bigger prop but less rpms.

So 12S = 490Kv, 12L= 350Kv, 16S = 380Kv, 16L = 270

You need to get used to looking at Kv (or rpm/volt) because it tells you quite a bit about a motor.

Can't help with where to buy them because I'm on the other side of the Atlantic .

Steve
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Old 03-13-2011, 08:36 PM   #12
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Originally Posted by slipstick View Post
S = short, L = Long can....sometimes things are straightforward .

The 12 and 16 are number of turns.

Generally more turns and/or longer can = lower Kv / more torque so bigger prop but less rpms.

So 12S = 490Kv, 12L= 350Kv, 16S = 380Kv, 16L = 270

You need to get used to looking at Kv (or rpm/volt) because it tells you quite a bit about a motor.

Can't help with where to buy them because I'm on the other side of the Atlantic .

Steve

Got it. Thanks.

...The Bum
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Old 03-14-2011, 12:29 AM   #13
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Originally Posted by Saddlebum View Post
Hi Denny;

Well... long story short, I'm going to dump the Monster 60 and buy a Hacker. You have educated me enough to understand that I have to learn about motor "efficiency" as well as kv ratings to understand what I am buying.

WOW! So much to learn!

The Hacker website confuses the heck out of me. It seems there are multiple motors that appear to be the same size, but have different specifications. What is critically missing is any reference as to which motors might be appropriate for different applications.

You mentioned the A50-16S and the A50-12S. Both seem to be made for 4S to 6S batteries with the 16S having more torque.

Would you be so kind as to explain what the "12" and "16" mean as well as the "S"? There seem to be 10's, 12's, 14's and 16's as well as "S" and "L" motors. VERY confusing.

Lastly, where do you guys buy your Hackers?

The Electric Motor Mystery is starting to become clearer!

Thanks
...The Bum
A lot of places have them, you can also buy direct from Hacker.
http://www.aero-model.com/Hacker-Bru...By-Series.aspx

As indicated below, the same exact motor frame size can give you vastly different performance levels from low RPM for Piper Cubs, to high RPM's for acrobatic models.

This is where motocalc helps. Also, if you look at the above thread, they give you typical prop sizes and RPM's.
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Old 03-14-2011, 01:35 AM   #14
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Default Hacker A-Series Analysis

The A50 12S, 14S and 16S all have the same "can" size, weigh the same, all use 4S-6S LiPo's and all have 14 poles.

The differences are:
..................12S .......14S .......16S

kv ..............492 .......425 .......378
Watts .........1250 .....1250 ......1250
Resistance ...0.016 ....0.021 .....0.026
Prop ...........14X7..... 15X8 ......16X10


I'm going to be putting this motor into a Senior TeleMaster to be used as a Club Trainer so I want long run times on a 5S, want the ability to quickly "throttle up" to pull it out of a students mess and want maximum ground clearance.

I'm thinking A50-14S. What do you think?

...The Bum
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Old 03-14-2011, 02:10 AM   #15
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Hi Bum you have been given a lot of great Advice here, getting the proper lipo count for a low KV motor can be a little hard, here is what i do.

on a 1000kv motor i use a 3 cell lipo in my plane.
on a 400-500kv motor i use a 6 cell lipo. to give me the same RPM/KV as a 1000kv motor on a 3 cell Lipo. Have i lost you yet Take care and have fun, Chellie

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 03-14-2011, 02:11 AM   #16
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Originally Posted by Saddlebum View Post
The A50 12S, 14S and 16S all have the same "can" size, weigh the same, all use 4S-6S LiPo's and all have 14 poles.

The differences are:
..................12S .......14S .......16S

kv ..............492 .......425 .......378
Watts .........1250 .....1250 ......1250
Resistance ...0.016 ....0.021 .....0.026
Prop ...........14X7..... 15X8 ......16X10


I'm going to be putting this motor into a Senior TeleMaster to be used as a Club Trainer so I want long run times on a 5S, want the ability to quickly "throttle up" to pull it out of a students mess and want maximum ground clearance.

I'm thinking A50-14S. What do you think?

...The Bum
I've got my A50-16S motor in a Showtime 50, with a 16X12 APC-E prop, and 6S2P A123 cells. (Or a comparable Lipo would be a 4500 Milliampere 5 Cell Lipo.

This power system hauls the model off the ground in 30-40 feet or so. Me thinks the Senior Telemaster would fly slower than the Showtime 50, so you don't really want a high reving motor for it.

If I've found the right model, that Telemaster is a BIG 10 pound model with 94 inch wingspan, and 1330 square inches. It's kind of pushing a Hacker A50-XS motor. I'd be inclined to go to a motor such as the Hacker A50-14L (Long Case) motor. This motor is rated for 6 to 8 Lipos, and would pull the Telemaster well with a 6S1P 5000 Milliampere Lipo and a 16X12 or 18X10 APC-E prop.

And, the A50-14L is rated for 6 to 8 series Lipos, so if you should want more power, the motor can provide it with two extra cells on the battery pack.

If you want to go to an 8S1P 5000 Mah pack, a good prop would be a 16X8 APC-E. That will run 1600 watts, pulling 57 Amps full throttle, and put out 129 watts per pound or so. This could be throttled back to about 60-70% throttle to double your flying time.

Of course you could go to what I've got, a Hacker A60-16M motor with 10S batteries, and fly straight up with it! Mine turns a 19X12 prop at 6800 RPM. But, that motor might tear the front end off of your model!
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Old 03-14-2011, 03:00 AM   #17
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Originally Posted by CHELLIE View Post
Hi Bum you have been given a lot of great Advice here, getting the proper lipo count for a low KV motor can be a little hard, here is what i do.

on a 1000kv motor i use a 3 cell lipo in my plane.
on a 400-500kv motor i use a 6 cell lipo. to give me the same RPM/KV as a 1000kv motor on a 3 cell Lipo. Have i lost you yet Take care and have fun, Chellie

No, not lost, Chellie. Actually it all starting to make some sense. Now isn't THAT frightening!

I was hoping to be able to run this airplane on the 5S Nano-Tech's I currently have and to use a 15" prop (maximum) as that is about all the clearance I have with my grass runway.

My motor choice MUST reflect that prop choice but I could buy a couple of 6S batteries.

...The Bum
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Old 03-14-2011, 03:19 AM   #18
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Originally Posted by Saddlebum View Post
No, not lost, Chellie. Actually it all starting to make some sense. Now isn't THAT frightening!

I was hoping to be able to run this airplane on the 5S Nano-Tech's I currently have and to use a 15" prop (maximum) as that is about all the clearance I have with my grass runway.

My motor choice MUST reflect that prop choice but I could buy a couple of 6S batteries.

...The Bum
Question: Is this the right model, 94 inch span and 1330 square inches? If so, seems odd its only got prop clearance for a 15 inch prop

DennyV
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Old 03-14-2011, 03:21 AM   #19
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Originally Posted by kyleservicetech View Post
I've got my A50-16S motor in a Showtime 50, with a 16X12 APC-E prop, and 6S2P A123 cells. (Or a comparable Lipo would be a 4500 Milliampere 5 Cell Lipo.

This power system hauls the model off the ground in 30-40 feet or so. Me thinks the Senior Telemaster would fly slower than the Showtime 50, so you don't really want a high reving motor for it.

If I've found the right model, that Telemaster is a BIG 10 pound model with 94 inch wingspan, and 1330 square inches. It's kind of pushing a Hacker A50-XS motor. I'd be inclined to go to a motor such as the Hacker A50-14L (Long Case) motor. This motor is rated for 6 to 8 Lipos, and would pull the Telemaster well with a 6S1P 5000 Milliampere Lipo and a 16X12 or 18X10 APC-E prop.

And, the A50-14L is rated for 6 to 8 series Lipos, so if you should want more power, the motor can provide it with two extra cells on the battery pack.

If you want to go to an 8S1P 5000 Mah pack, a good prop would be a 16X8 APC-E. That will run 1600 watts, pulling 57 Amps full throttle, and put out 129 watts per pound or so. This could be throttled back to about 60-70% throttle to double your flying time.

Of course you could go to what I've got, a Hacker A60-16M motor with 10S batteries, and fly straight up with it! Mine turns a 19X12 prop at 6800 RPM. But, that motor might tear the front end off of your model!
You have the right model, Denny. It's a big "floater", easy to see and easy to fly. Speed is not desirable but torque is.

As I mentioned to Chellie, I believe I am limited to a 15" prop. That only gives me 2" to the ground so I'll be sporting many a prop with grass green tips this summer.

All of the motors I mentioned above deliver 1250 Watts and will provide 125 Watts per pound which I believe is more than enough for a trainer that will probably be flown at half throttle most of the time.

(What I don't understand is why these three different motors, with three different kv ratings all pull the same amount of watts and which one has speed and which one has torque).

If I go with the long case motor, I'll have to buy more batteries as I have no 6S's right now. That's why I'm leaning toward the short case choices.

That said, the A50-14L (6S-8S) looks like it will run a 15x10 prop. At 1650 Watts that motor looks like it will pull my Tele off the ground way too fast. Isn't 165 watts per pound a bit over-the top for a trainer?

(I run my T-34 at 150 watts per pound and it will climb straight up 200 to 300 feet from level flight.)

Am I getting this right, or am I still on the left side of the learning curve?

Thanks
...The Bum
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Old 03-14-2011, 03:25 AM   #20
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Originally Posted by kyleservicetech View Post
Question: Is this the right model, 94 inch span and 1330 square inches? If so, seems odd its only got prop clearance for a 15 inch prop

DennyV

It's an old design, Denny. Maybe that explains the gear.

Right now it is sitting on tall floats and from the center of the motor hub to the ground is exactly 12"

On wheels, that becomes 10".

So a 15" prop gives me just 2 1/2" to the ground and I fly in 2" to 3" grass all the time.


...The Bum
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Old 03-14-2011, 03:35 AM   #21
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Bum just bend up some new landing gear and make them longer then you have more prop clearance. Had to do that to one of mine so I can fly off our field I am in the same boat with green tipped props. this will at least let you use a bigger prop.
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Old 03-14-2011, 03:38 AM   #22
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Originally Posted by Saddlebum View Post
You have the right model, Denny. It's a big "floater", easy to see and easy to fly. Speed is not desirable but torque is.

As I mentioned to Chellie, I believe I am limited to a 15" prop. That only gives me 2" to the ground so I'll be sporting many a prop with grass green tips this summer.

All of the motors I mentioned above deliver 1250 Watts and will provide 125 Watts per pound which I believe is more than enough for a trainer that will probably be flown at half throttle most of the time.

(What I don't understand is why these three different motors, with three different kv ratings all pull the same amount of watts and which one has speed and which one has torque).

If I go with the long case motor, I'll have to buy more batteries as I have no 6S's right now. That's why I'm leaning toward the short case choices.

That said, the A50-14L (6S-8S) looks like it will run a 15x10 prop. At 1650 Watts that motor looks like it will pull my Tele off the ground way too fast. Isn't 165 watts per pound a bit over-the top for a trainer?

(I run my T-34 at 150 watts per pound and it will climb straight up 200 to 300 feet from level flight.)

Am I getting this right, or am I still on the left side of the learning curve?

Thanks
...The Bum
Is your grass cut real short? Or is it a public park or something? If the grass is more than a few inches high, you need power to get it going.

As for the different winds on that motor, for the most part the maximum power you can generally pull out of a model brushless motor is about 100 watts per ounce of motor weight. So, a 15 ounce motor could under proper cooling and good design put out about 1500 watts or so.

But, we have the different "winds" issue. Have you ever ran across a shop 120 VAC motor that can be connected as 120 OR 240 Volts AC? What these type motors have is two windings, that can either be put in parallel for 120 VAC, or in series for 240 VAC. You've got to go inside the motor to reconnect the wires for the other operating voltage.

Same thing in our brushless motors, but rather than re-connecting, you've got to rewind the danged thing. Or build it with different winds.

If you've peeked inside these motors and looked at the windings, you've noted these windings must fit into a slot in the steel structure. And this slot can only hold so much copper wire, or it won't fit. So, you could as an example put in 10 turns of 0.05 diameter wire, 20 turns of 0.025 diameter wire, 40 turns of 0.012 wire and so on.

Now, for the 0.05 wire, you might find its maximum safe number of Lipo cells would be 2 cells. And that would be 4 cells for the 0.025 and 8 cells for the 0.012 wire. But since the wire SIZE is smaller for the 0.012 wire, you must reduce its maximum current by the same amount.

So, perhaps the 0.05 wire can handle 60 amps at 7 volts, the 0.025 wire could handle 30 amps at 14 volts, and the 0.012 wire could handle 15 amps at 28 volts. (These are examples to show the idea, not necessarily valid wire sizes!)

And since power in watts equals volts times amps, 60 amps times 7 volts is 420 Watts. And 30 times 14 is 420 watts, and 15 times 28 is again, 420 watts.

Now, you can put 14 volts on the motor wound with 0.012 wire, 1/2 the "rated" voltage, but you'd only get 1/2 the power out if it. But, it will turn a larger diameter propeller at a lower RPM.

Next time you get a chance, look at the windings of a high quality motor such as a Hacker and look directly at these windings. All available space is completely filled with copper wire. And then compare that to some of the $25 "Less expensive" motors. 1/2 of the available winding space is air. That cuts into how much winding resistance your motor will have, and with it, lower motor efficiency. Some of the motors of the same core size can have a winding resistance 3 or 4 times that of a high quality motor of the same size.

Hope that helps!
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Old 03-14-2011, 03:42 AM   #23
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Originally Posted by gramps2161 View Post
Bum just bend up some new landing gear and make them longer then you have more prop clearance. Had to do that to one of mine so I can fly off our field I am in the same boat with green tipped props. this will at least let you use a bigger prop.
Agreed:
Might be the way to go. (Or just buy a different landing gear at the local hobby shop, or Tower Hobbies or similar.)

Funny, my props are always red tipped. Seems they are pulling the mosquitos out of the grass after they've had dinner on us.
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Old 03-14-2011, 07:05 AM   #24
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Not sure what the motor calculator is telling you but my Sr. Telemaster flys very well with a 580Kv motor on 5S batteries with a 15X8 prop. It has also flown on 4S with out any difficulty.

I have not weighed it recently but have done some mods, bolt on wing, multiple gyros, camera, etc, which upped the weight some & IIRC its now in the 12/13lb range AUW.

Most flights are at 1/2 throttle or less which will keep the plane airborne for about 10 minutes with a few missed approach margin. Normally about 3/4 throttle will take the plane off the runway with no excitement.

With a full throttle takeoff it will imitate an F-15 on full burner with a 60 degree climb out to 3 mistakes high. It also has enough power to do loops from level flight.

Something to keep in mind with a Sr. Telemaster is that both the main wing & elevator are airfoils so it does not take much airflow over the plane for it to fly. In a 7-8mph wind down the runway it can be landed with just about zero rollout.

The SK5055/580 in the plane is about a year old now & is still performing very well. The fact that it cost about $35 kind of makes you smile.

Since I am a believer in power can get you out of trouble some of the guys at the field joke about my penchant for what they consider is my overpowering the planes a bit.

Kevin
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Old 03-14-2011, 07:15 PM   #25
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GREAT stuff Denny. It ought to be a sticky!


Is your grass cut real short? Or is it a public park or something? If the grass is more than a few inches high, you need power to get it going.

The grass is cut at 2" and seldom grows beyond 4". 3" mostly. This is our Club flying field.


If you've peeked inside these motors and looked at the windings, you've noted these windings must fit into a slot in the steel structure. And this slot can only hold so much copper wire, or it won't fit. So, you could as an example put in 10 turns of 0.05 diameter wire, 20 turns of 0.025 diameter wire, 40 turns of 0.012 wire and so on.

Now, for the 0.05 wire, you might find its maximum safe number of Lipo cells would be 2 cells. And that would be 4 cells for the 0.025 and 8 cells for the 0.012 wire. But since the wire SIZE is smaller for the 0.012 wire, you must reduce its maximum current by the same amount.

So, perhaps the 0.05 wire can handle 60 amps at 7 volts, the 0.025 wire could handle 30 amps at 14 volts, and the 0.012 wire could handle 15 amps at 28 volts. (These are examples to show the idea, not necessarily valid wire sizes!)

And since power in watts equals volts times amps, 60 amps times 7 volts is 420 Watts. And 30 times 14 is 420 watts, and 15 times 28 is again, 420 watts.

Now, you can put 14 volts on the motor wound with 0.012 wire, 1/2 the "rated" voltage, but you'd only get 1/2 the power out if it. But, it will turn a larger diameter propeller at a lower RPM.

Next time you get a chance, look at the windings of a high quality motor such as a Hacker and look directly at these windings. All available space is completely filled with copper wire. And then compare that to some of the $25 "Less expensive" motors. 1/2 of the available winding space is air. That cuts into how much winding resistance your motor will have, and with it, lower motor efficiency. Some of the motors of the same core size can have a winding resistance 3 or 4 times that of a high quality motor of the same size.

Hope that helps!

Yes, this helps tremendously! When I bought the Monster 60 (for $35.40) I bought it because it "looked" like a well built motor and was rated at 400kv. Thinking the 400kv number was telling me it had power, I bought it. Also, it was rated for 5S to 7S LiPos. Just what I needed I thought.

Turned out it was an inefficient motor. It has a resistance of .06 ohms. The A50-14S Hacker has a resistance of .021 ohms. To a Newbie like me, those numbers look pretty close but as I have learned, they are not. OK, one is triple the other but they still look like pretty small numbers.

I need to learn how the ohms numbers factor in with the watts, volts and amps to really understand why such a small difference in ohms makes such a huge difference in actual performance.

Is there such a thing as a "good ohms" number? Should I not consider any motor with an ohms rating over a certain number?

And... looking at the 12S, 14S and 16S; do I understand correctly that the 12S will turn a smaller prop at a higher RPM than a 16S ?

If so, the 12S would be more suited to a Warbird or Pattern plane and the 16S to a slower airplane even though they both produce the same wattage? Did I get that right?

So many questions... so little time!

Thanks for all the knowledge you have shared with us all.
...The Bum
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