Motors ...for beginners - please keep it simple

[Chris Bott - Moderator]

Absolutely spot on Malcolm, can use either end. I use the bolted on prop adapter whenever I can, for the reasons you've already worked out.

[Josip Vrandecic -Mes]

Hello everyone,especially Tim,please I need an answer.I have E-max motor (BL 2205),

with three black cable (lines)....my ESC (fentium 18 A) have three blue cable with markings A,B,C .

Q:How to conect motor and ESC...correct ?

Thanks in advance

Absolute beginner

Jo.

p.s.Sorry, but I du not need to do a new post .

[Chris Bott - Moderator]

Hi Josip

 

It's easier than you think.

Just connect one black cable to each blue cable.

Then see which way the motor turns.

If it spins the wrong way then swap two of the connections.

 

Good luck

Chris

[Pete B]

Just connect the three cables from the motor to the ESC and, without a propellor fitted, start the motor.

 

If it turns in the wrong direction, just swap any two of the cables. It will then turn in the correct direction.

 

It's worth marking the cables when you have the correct setting so you can re-connect them correctly at any time.

 

Good luck with your electric adventure, Josip - you will be pleasantly surprised by the result!

 

Pete

[Josip Vrandecic -Mes]

Hi Chris and Pete,means the similar as the large AC electric-motors(three phases).

Thanks indeed

All the best

Jo

 

Edited By Josip Vrandecic -Mes on 29/08/2011 10:25:32

[Tim Mackey]

Sorry Jo - been too busy flying and stuff to spot your post until now.

As you can see, we have [plenty of knowledgeable chaps here to help - glad you're sorted now.

Incidentally, this, and many other things to help beginners can be found HERE.

The second and third post of that thread deals with connecting things up

[Josip Vrandecic -Mes]

Dear Tim,thanks anyway,I know you are busy,but there are enough experts on our forum.

I have new questions for you soon.

Cheers

Jo.

Edited By Josip Vrandecic -Mes on 29/08/2011 20:22:36

[Douglas Dale]

Hi

i have just had two brushless outrunners delivered

they have three black wires with nothing ti identify what

each wire is can you help

[Chris Bott - Moderator]

Hi Douglas.

It's simpler than it looks. The three wires connect to the three wires on the brushless speed controller. In any order. Sometimes this is enough, sometimes the motor runs backwards. If this happens, just swap two of the wires.

Oh and welcome to the forum, we try our best to be a friendly bunch

 

Edited By Chris Bott - Moderator on 02/03/2012 15:19:50

[Myron Beaumont]

I wonder if you could apply the same principle with the "fairer sex " .Swop any one of three & they're bound to work in the right direction for you . I think not ?

Sorry !

Edited By Myron Beaumont on 02/03/2012 15:23:26

[Spikey]

OK ... I'm managing to absorb quite a bit of this electrickery lark, but some of it still isn't falling into place. So ...

My teach-self-to-fly-on-the-cheap Pipelagger now has a 1550kV Turnigy Donkey motor on it, and for the time being I'm messing about using a cheapo 20C 2S 500mAh lipo. With the 8x6E prop on it, I was getting 7.5A, 6.7V and 48.5W (give or take) after 30 secs at full power just now.

What I can't get my head round is ...

1. What do those figures tell me about that prop for that motor?

2. Given that I'm into relatively slow flying (and FWIW am aiming to be able to fly in a breeze as opposed to no wind at all), what if anything might I gain by using instead a 950kV motor with a different prop (such as what, though, I have no idea)?

[Ed Anderson]

Posted by Spikey on 28/02/2013 19:04:25:

OK ... I'm managing to absorb quite a bit of this electrickery lark, but some of it still isn't falling into place. So ...

My teach-self-to-fly-on-the-cheap Pipelagger now has a 1550kV Turnigy Donkey motor on it, and for the time being I'm messing about using a cheapo 20C 2S 500mAh lipo. With the 8x6E prop on it, I was getting 7.5A, 6.7V and 48.5W (give or take) after 30 secs at full power just now.

What I can't get my head round is ...

1. What do those figures tell me about that prop for that motor?

2. Given that I'm into relatively slow flying (and FWIW am aiming to be able to fly in a breeze as opposed to no wind at all), what if anything might I gain by using instead a 950kV motor with a different prop (such as what, though, I have no idea)?

 

 

Welcome to the wonderful world of electric powered flight.

First let me recommend an online book that is free. It can explain a lot.

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT

 

 

Now as to what those numbers mean. I presume you have a watt meter to give you those readings. Good.

 

 

My teach-self-to-fly-on-the-cheap Pipelagger now has a 1550kV Turnigy Donkey motor on it, and for the time being I'm messing about using a cheapo 20C 2S 500mAh lipo. With the 8x6E prop on it, I was getting 7.5A, 6.7V and 48.5W (give or take) after 30 secs at full power just now.

 

 

 

First of all, the power (48.5Watts) is important in relation to the weight of your aircraft. I use the watts/pound forumula to decde how much power I need to fly my aircraft in the manner I wish to fly it. For a slow flyer I would want at least 50 watts/pound. If your all up weight is around 1 pound then you are doing fine. If it is two pounds then I would say you are under powered.

 

7.5 amps is important in relation to your battery and speed control. Most ESC, electronic speed controls, are rated in the number of amps they can handle. So as long as yours is rated for 8 amps or more, you are fine.

 

It is also important in relation to your battery. Your battery is rated for 10 amps max. So your 7.5 amps is within the rating of the battery, and that is good.

 

6.7V - Now I see a problem. A fully charged 2 cell lipo pack would be 8.4V. Under load it should be able to hold up at least 7.4V for longer than 30 seconds at full throttle. Yours is only showing 6.7V. Something is wrong with the battery. you have a problem.

 

I did a search on HobbyKing for a 1550kV Turnigy Donkey motor and found nothing. So I have no idea what the rating is for your motor. A link to the motor would be most helpful. I have no idea if that is the recommended prop or if you are overloading the motor or what.

 

Ed

 

 

Edited By Ed Anderson on 28/02/2013 19:25:40

[Simon Chaddock]

Spikey

Those figures tell me that you are working that 500mAh battery quite hard although the motor is within its limits .

1. Taking 7.5 amps is 15C from a 500mAh battery. It will be exhausted in 4.5 minutes at full power.

2. The voltage at 6.7V is getting very close to the 3.3V minimum per cell for a LiPo.

I would suggest doubling or even tripling (1500mAh) the battery capacity. This will put much less strain on the battery and it will keep the voltage much better and so improve the motor performance.

Say the bigger battery can maintain 7.5V instead of 6.7V.

0.7V difference might not sound much but the power generated is proportional to the square of the voltage so it will deliver roughly 25% more power - close to 60W just by fitting a bigger capacity battery.

You probably wont need full power all that much but you won't be straining the battery when you do.

The motor and prop combination you have is fine for a 2s.

If you fit the same size but lower kV motor along with a bigger prop it will draw the same Watts from the battery so you end up with a similar performance.

Don't expect your Pipelagger to handle too much wind!

I hope this helps

[Simon Chaddock]

Ed

The motor spec is here

Max 100W

[Ed Anderson]

HobbyKing Donkey ST2004-1550kv Brushless Motor

 

Motor Specs:

 

Specs:
RPM/v: 1550kv
Dimensions: 28 x 17mm
Shaft: 3.0mm
Voltage: 7.4v~11.1v
Weight: 33g
No-load current: 1.0A @ 11.1v
Max Current: 10A
Max Watts: 100W
Mounting Holes: 33mm

Prop Data:
7035 - 7.4v - 3.5A - 180g Thrust
8043 - 7.4v - 6.4A - 285g Thrust
7035 - 11.1v - 6.5A - 370g Thrust

 

My teach-self-to-fly-on-the-cheap Pipelagger now has a 1550kV Turnigy Donkey motor on it, and for the time being I'm messing about using a cheapo 20C 2S 500mAh lipo. With the 8x6E prop on it, I was getting 7.5A, 6.7V and 48.5W (give or take) after 30 secs at full power just now.

 

First note is that I dont' see a recommendation for an 8X6 prop anywhere, but it might be OK.

Assuming your battery was fully charged when you started, I would say it is defective/shot!  It should be able to hold over 7.4V for more than 30 seconds.

 

But even if it holds 7.4V and your amps go to 9, that is 66 watts.   Now, how much does the plane weigh, all up?

Edited By Ed Anderson on 28/02/2013 22:14:15

Edited By Ed Anderson on 28/02/2013 22:24:30

[Spikey]

Thank you Simon. Ed, all up weight is 295g and I realise now that the battery I used was the one I put on the shelf last week after giving it a storage charge ...

[Ed Anderson]

Well, that will certainly impact your testing and produce confusing results.

At 295 grams, and with a fully charged battery, you shoud have plenty of power.

Rather than that 8X6 prop, you might consider a 9X5 if that is available. If you are looking for slow flight, this might be a good one to test.

[Peter Miller]

Hi Tim.

I need some advice fr a friend.

I gave him my Great Plane Specktra glider which flies really well o a speed 600 motor and 6 or 7 cell NmH battery.

He has a 960 Kv brushless motor and suitable ESC with 2200 MaH batteries salvaged from a Horizon Hobbies Spitfire. This motor is driving a 9" prop with what he says is about 45 degree pitch.

The Spectra is about 72" span

Would this motor fly the Spectra and what prop should go to.

NOTE he does not have Watt meters etc. He does a lot of flying with stock ARTFs.

As you will probably know my electric experience ended with Speed 600s etc

[Ed Anderson]

I know the Spectra quite well. Here are some thoughts.

* If you just swap the NiCd pack with a 2S lithium that is sized for 20 amps it will fly better because it will be lighter. Still not a fantastic climb but it takes nothing to do this. A 2200 mah 20 C pack would be great.

That speed 600 on 7 cell nicad was taking in about out about 160 watts but only delivering about 100 watts to the prop which as I recall was an 8X4.

Now, which spitfire?

If I search on HH for Spitfire this is the only 950 kV motor that comes up.   There are no specs given on the motor and I can't find a spitfire using this motor on their site so I am guessing this is a model they no longer sell. The current Spitfires use different motors.

http://www.horizonhobby.com/15-bl-outrunner-motor--950kv-pkz5116

I am assuming the prop  is a 9X4.5 as props are not marked in degrees they are marked in pitch according to how many inches the prop would move forward through the air on each turn if there were no slippage.

 

This motor seems to be close to the motor your friend has so we will use the specs from this motor:

http://www.horizonhobby.com/power-15-brushless-outrunner-motor--950kv-eflm4015a

 

You did not say what voltage, how many cells,  the battery pack would be and that would be critical to know in order to estimate the wattage the motor will draw. And you did not say what amperage rating the ESC had so I have to guess.

Here is a WAG. 3S pack, 9X4.5 prop prop, probably draw 20 amps for about 220 watts input and about 180 to the prop. That would nearly double what the Speed 600 was doing. So that would be fine. Glider would probably climb at a 45 degree angle or steeper as compared to about a 25 degree climb on the speed 600 and a 7 cell NiCd pack.

 

Should work fine.

 

 

 

 

 

 

Edited By Ed Anderson on 20/08/2016 16:59:58

Edited By Ed Anderson on 20/08/2016 17:00:37

[Peter Miller]

Hi Ed, That has been very helpful.

The Spitfifre was bought several years ago, at least 4. The battery is a 3S 22Ma battery so that should add enven more power.

My friend was on the phone. He has no idea of pitches. I was a bit puzzled because of course the pitch varies along the blade. but I quoted him for lack of a better figure.

Many thanks for the info. I will pass it on to him and he can start coversion.

I did give him two NmH ESCs which can be used with Lipos by swapping a plug over but they didn't work so this might get him going. The Spectre was mine and I passed it on to him.

Currntly I am working ona smaller glider for Cox 049 or 1 cc engine.

[Ed Anderson]

Good luck with the new glider. I have never flown a glider that was launched with a glow engine. I have only flown pure gliders and e-launched gliders.

 

Why would you use a glow engine rather than electric? Electric can be restarted and controlled. A glow can't.

Do you put a folding prop on a glow engine?   I would assume not as it would make it tricky to start.

 

 

Edited By Ed Anderson on 20/08/2016 19:00:58

[Peter Miller]

It is more of a challenge.

I once made two flghts in an afternoon, both over 50 minutes long. Then I had an Easy Pigeon and had a flight of 1 hour 16 1/2 minutes and could have gone on with at least another climb.

I had a couple of glider powered with Cox Texaco .049. Staying p with those for decent lengths of time on a fixed engine run was far more challenging.

Hitting a thermal to took my up into a white fluffy cloud was great.

I have a friend who flies glider off the bungee.He refuses to use electric power. He just likes to do it off the bungee. Even really small gliders.

I have designed my latest so that it can easily be built for electric power as I know that is how 99.9 percent of people will build it. See Kitehawk build blog

​It is a cross between my Sunbeam (cox) and my Easter Eagle (speed 600)

[Ed Anderson]

That is the joy of the hobby. We can all approach it a little differently yet share in the same experience as we find lift and take it high into the sky.

Clear skies and good lift to you!

[Tim Mackey]

Hi Pete. Personally I would go for a bigger prop - a 72" Model seems rather large for a 9" prop. If he wants to use a 3s lipo (which id recommend ) then on a 960kv motor I would probably prop at at about 12 X 6 or so. I use an 1100 kv motor on a similar setup and its pulling around 38A. 😊

[Peter Miller]

Hi Tim

Thanks for that. I will pass it on to Alan.

Peter