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Jul 05, 2004, 09:50 AM
Thread OP

General Question on brushless specs/performance


I placed this question in a response to someone's brushless slow stick mod thread in the parkflyer section, but I feel it would be more appropriate here.

I'm sorry, I'm new to this hobby and don't understand all the terminology yet. Have gotten pretty comfortable with my Slow Stick and it's stock 350 motor. Can fly 40 min on my 2s 1500 MaH lipos and feel in control the whole time. Loops are easy and starting with inverted flight.

so, today I bought a Park 400 brushless with the adapter plate for the SS gearbox. It is a EFLM1100 Park 400 4200KV. Also got a brushless Castle Creations Phoenix 25 A ESC. (I debated the 1000 Park 370 but decided on the bigger one for future planes...)

How does this compare with the 2015/4100 that I know others have placed in a slow stick? I am assuming the 4100 is KV, slightly less than my 4200. What does the 2015 mean?

Is there a thread that discusses power output from brushless, compared to brushed? I understand electtrical terminonogy, current draw etc, but am not surre how to tell how that translates to thrust, rpm etc for a particular motor/batttery combo.

Many thanks in advance!
daniel
Last edited by seftonde; Jul 05, 2004 at 09:53 AM.
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Jul 05, 2004, 10:17 AM
Registered User
Aio_1's Avatar
I'm not familiar with the 'Park 400 4200kV' but going by the numbers it may be a re-badged Himax 2025-4200.
Do you know if this is the case or can you post more data on your motor (especially a picture or link to a vendor listing if you have one)

If it is the 2025-4200 then it is the same as the 2015-4100 but the stator is 25mm long rather than 15mm and the windings are different. It can produce more torque and handle higher current but it is a longer and heavier motor. There are plenty threads around which will give you info on suitable setups if this is the same as the motor you have.

As for comparing brushed and brushless motors; it is impossible to answer that question. It depends entirely on the application and the specific motors.
It is possible to get very good efficiency out of cheap brushed motors and bad efficiency out of expensive brushless motors depending on how they're used. Generally a brushless motor can handle a lot more power for it's size than a brushed motor but that is only a small part of it. In many applications a brushless motor isn't warranted but for very high power it is usually necessary.

Aidan
Jul 05, 2004, 10:19 AM
Registered User
Andy W's Avatar
Every brushless motor is going to be different to every other - there's no simple way to compare them all. kV alone is not going to tell you much either.

In general, however, brushless motors are more efficient than brushed motors because they have more efficient commutation (but more expensive controllers to enable this.) This means that for the same power in, you get more power out. With small can motors like that provided with the slow stick, your efficiency is something like 50% - half the input power is wasted as heat, friction, etc. A cheap brushless motor will have efficiency in the 70%+ range - so from a performance standpoint, it looks like the model has 50% more performance (power) for the same input power. This is usually what sells first-time brushess users..

There are exceptions to the above - there are low efficiency brushless motors (smaller motors tend to be less efficient, plus - for example - the Jeti Phasors are not all that efficient - but are still worth buying and are very useful in some applications) and there are high efficiency brushed motors. I always use "in general" when discussing this..
..a
Jul 05, 2004, 03:47 PM
Thread OP
Thanks, everybody,

I fell better that everything is different - was looking for some sort of common denominator indicating power etc.

Aiden - my motor is an:
Eflite Park 400
Model: EFLM1100
4200 Kv
Io = 1.8A
Ri = .02 ohms
Kt = .23
Current = 2-13A
Max Current = 18A
Cells 6-12 (i have two cell Lipos, 7.4V 1500MaH
20mm diameter
40mm case length
68g weight

Thanks again, everyone
daniel
Last edited by seftonde; Jul 05, 2004 at 03:50 PM.


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