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Author Topic: Whats all the jargon  (Read 635 times)

Offline Wynn Robins

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Whats all the jargon
« on: June 08, 2009, 08:56:31 PM »
For those of us that have NO idea on electrics - like me - is the a list that explains all the acrynoms, jargon that you read about......
In the battle of airplane versus ground, the ground is yet to lose

Offline Dennis Adamisin

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Re: Whats all the jargon
« Reply #1 on: June 08, 2009, 09:07:48 PM »
Not that I have seen.  Unfortunately the list could quickly get unmanagable to "shot gun" it all.

You might want to just take a look at the sticky thread (top of this forum) called "List your set-ups".  That shows what people are using and also includes much of the jargon.  Any terms that do not look familiar - give a shout and we can help.

Just for starters: are there any particular terms you would like to start with???
Denny Adamisin
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As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Alan Hahn

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Re: Whats all the jargon
« Reply #2 on: June 08, 2009, 09:55:11 PM »
I agree with Dennis--there are a lot of buzz words here. I recommend looking at the sticky above where people have listed planes and the power systems they have used.

Generally speaking, a certain size plane will need a certain amount of watts to fly it. There will be small +-15 % variations depending on how people optimize things. If you look you will see that there is no single common setup--most are pretty close in capability (when you scale for plane size) which means that you will have some options to choose depending on how much you want to put into this.

Offline Wynn Robins

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Re: Whats all the jargon
« Reply #3 on: June 08, 2009, 10:23:49 PM »
hmmmm

scorpion 3020-12 KV=1088/volt--stock  ??????  I know this is the motor....but what does it mean

also battery packs like Thunder power 5s2p4200 = what are all the numbers etc referring too....

like I said, I know NOTHING about electrics
In the battle of airplane versus ground, the ground is yet to lose

Offline Dennis Adamisin

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Re: Whats all the jargon
« Reply #4 on: June 09, 2009, 06:32:37 AM »
hmmmm

scorpion 3020-12 KV=1088/volt--stock  ??????  I know this is the motor....but what does it mean

also battery packs like Thunder power 5s2p4200 = what are all the numbers etc referring too....

like I said, I know NOTHING about electrics

* Ugh you started with the toughest one!  Unfortunately there is no single "standard" for depicting motor sizes.  I believe (and "Scorpion Man" Alan will correct me if I miss it) the Scorpion 3020-12 is a motor with a 30mm diameter X 20mm  long commutator.  I believe the -12 is the number of wire windings.  I believe the AXI and Scorpin motors (and doubtless others) use this standard for identifying their motors.

Rimfire, Turnigy and some others use a simple outer diamter and overall length to describe their motors.  I am currently using a couple of Rimfire 35-36 motors that are 35mm in diameter x 36mm long (plus the shaft).  I also have a Turnigy 35-42 - it is 6mm longer than the Rimfires.

It does get a little confusing when you compare motors from one brand to the other - that is one reason why the "list your set-up" thread was started - so we can compare different packages of compnents.


* kV is the number of RPM's a motor generates per volt.  so the 1088 kV motor will run 1088 RPM on 1 volt

* 5S2P refers to the battery configuration in this case 5S means 5 Lipo (oops, that's lithium polymer) cells in Series.  2P means that there is a 2nd pair of cells wired in parellel ti the first, thus doubling the amperage capacity  of the battery which in your example would be the 4200 mah number.  Put another way the 5S2P 4200 battery pack is actually constructed of 10 x 2100 mah cells.

It DOES sound intimidating at first however, you might be ammazed at how easy it is to get a handle on it all...
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Alan Hahn

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Re: Whats all the jargon
« Reply #5 on: June 09, 2009, 08:49:28 AM »
To add some things to Dennis's excellent exposition,

Brushless electric motors have many ways to specify what they are, but basically what matters in making power is the active volume of the motor---that's where the copper wires are wound and where the permanent magnets are located. The Scorpion and Axi (and some others) specifiy this size as Dennis mentions. So if you want to go between different brands, trying to compare those dimensions is the most useful. Another detail is that all motors have some inefficiency, and the only way they can shed heat is through the outer shell, so the more power you make, the more you need to dissipate into the air. That's why as your needs go up, the physical motor itself will get bigger (diameter and length). Another item of interest, is that the power making part of the motor is made out of mainly copper and iron, so most comparable motors will have similar weight.

There are similar considerations about the batteries. Currently the battery most of us are using is the Lithium Polymer--it maximizes power vs the weight of any other battery out there. Every plane needs a given amount of energy  (power in watts times flight time). So that total energy will set the total weight of the battery--since with some variations, you have a nominal energy/ounce of battery. How you arrange that energy is given by the battery designation. For example, if you start with 6 cells each of 2100mAHr capacity, you can arrange them in in two common configurations---a 6s1p2100 pack (6 cells in series), or as a 3s2p2100 pack (two 3s2100 packs hooked up in parallel). Both configurations carry the exact same amount of energy, just arranged differently.

To use the energy effectively, we will choose the "kV" of our motor to match the battery. Recall that in any case you want to turn a prop at some target rpm. A 6s1p2100 pack will have twice the voltage but half the amperage output of a 3s2p2100 pack. So for the 6s pack, we will chose a motor with half the kV than the one we would choose for the 3s2p pack. It is your choice! 

I note these options because I am exactly doing this right now with my Vector--I have a motor with a 1088kV and will use two 3s1p2100 packs hooked up in parallel. If I had the same exact motor but wound to give a 544kV, I would hook up the two packs in series (to make a 6s equivalent). Why not just use a single 3s1p4200 pack (made out of three 4200mAHr cells)? --I could but the one I do have is a very tight fit in the Vector (also I only have one).

So you can see there are a lot of ways to skin the same cat--and that can add to the overall confusion sometimes (I have probably helped here in that regard!).


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