Motor Equivalents

[Steven Mills]

I'm a fairly new to electric flying, tend to install recommended motor etc. What I would like to know is how do you compare 1 motor with another from a different supplier.

I'm looking for an equivalent to the Hacker A30-10XL.

Is this a good motor, seems expensive to me, when it looks like I can get a motor from overlander for half the cost.

Thanks for any help.

Steve

[Mouldy]

From the little Ive learnt Hacker, Axi, and a few others are at the top of the tree, hence the cost. Although how much of this cost is to do with branding Im not sure!

[Tim Mackey]

Well that is always a part of it, but one does usually expect to pay a bit more for quality.

Its often the internal construction of such things which vary, EG Mega motors and MVVS etc use top quality magnets, laminated and carbon fibre wrapped etc....bearings are often sealed better against dust ingress and so on and so on. I tend to use the principle that the more I value a plane the more I am likely to use top spec ESC and motor etc. For my everyday fomie fliers, then cheap and cheerful will do, after all it is quite easy to spend more on just an ESC than the model itself - which seems a little daft ?

Having said that, I have NEVER had a failure with any JETI stuff, but overlanders Tornado ESCs..... only owned 2, and they both let out the magic smoke after a few flights at under their so called spec. 

[Piper Cub]

Hi.

Sorry Im new to electric but who would you say were the top 3 or 4 brushless motor manufacturers?

Ta.

[David Ashby - Moderator]

I'll name one - MVVS and see what others think?

[Tim Mackey]

MVVS

HACKER

MEGA

PLETTENBURG 

AXI

JETI PHASOR

KONTRONIK 

[Piper Cub]

What's the best way to work out the 'required' brushless motor for your model?

I've seen a couple of motors where the manufacturer has said the brushless motor is equivalent to, say, a 40 - 60 sized ic engine. However, the kv on one is 500kv and 900 watts while the other is just given as 600kv. Yet another as 900kv but being the equivalent of a 35 ic engine and suitable for the weight of model I have but the model manufacturer states a 40 to 46 ic engine is needed.

How do you decide which is best suited for your needs? I know this forum is a great place for info but it would be good to work out whats required instead of having to ask all the time

[Tim Mackey]

Practice grasshopper...practice - and read alot of course

[scott cuppello]

Piper Cub, you havn't actually told us what the application is? Some examples, if it's a 0.46 size aerobatic, you are aiming for around 150 watts per pound, low KV, big prop with loads of torque.....if it's a 0.46 size warbird, 100 watts per pound, it needs to be scale fast, so usually [but not always....personal preference]...higher kv, smaller prop [you get the added benefit of a nice bit of prop noise to bring them to life in the air]....now if it's a Piper Cub....60-100watts per lb will do, low kv, big prop for scale flying.....what is it for? How's it going to be flown?....this is the versatility of electric flight!

[Piper Cub]

Its for an approx 1\5th scale Piper Cub, weight about 5.5lbs. Obviously slow scale flying.

But having said that, that was the point of my question. You've identified 3 different scenarios each with their own motor requirements. How is the newcomer to electric supposed to sort out what motor ratings are best for the type of plane you fly?

With an ic plane, its fairly straightforward, a 40ic will produce almost the same power characteristics no matter what its application ie same fuel, same prop.

[Tim Mackey]

Well thats not strictly true - a rossi piped 40 2t will suit a whole different craft to a Saito 40 4t - they are both 40 IC but have vastly different uses. Even 2 different 40 size 2 strokes can have different power curves and torque...EG: a short stroke ABC engine with different porting and timing will have a different rev / power band to ringed one with a long stroke. At the moment you are viewing all the different flavours available in electric powertrains as a nuisance and over complication ( and I CAN see that could be so... ) however, what you need to try and do is forget making comparisons with old fashioned IC engines, and their narrow performance band and restricted prop sizes, and start to view electric motors as being far more versatile. Using the same motor with a different prop, or a different battery opens up flexibilty that simply isnt possible to find in an internal combustion engine.

As I say...I can completely understand your frustrations and several attempts have been made by well meaning people to simplify things, but frankly it is quite a learning curve if you want the best results. You will need to keep reading and asking questions ( it's how EVERYBODY learns trust me! ).

It can be a bit overwhelming to try and get to grips with all the numbers and factors involved, so do what is normal in such circumstances..... learn a bit at a time, and break down a big job into smaller manageable chunks. I suggest to start with, get your head around and understand one bit of crucial info THEN when you UNDERSTAND IT, move on to the next bit.

BIT1 - Low K/V motors swing big props slower, and use less current, - think of them as the high torque 4 strokes of the electric world if you must. HIgh KV motors swing small props ( and fans ) fast, have less "torque" but use more juice to achieve these high revs - the high revving little screamer 2 strokes of the IC world...again if you must compare

BIT 2  - I told you - UNDERSTAND BIT1 FIRST !!

HTH

[scott cuppello]

No, it's quite simple, you need a 0.40 equivalent out-runner, low kv [rpm per volt], so basically, a motor of around 500-650 watts.

In fact, based on the AUW, a 0.30 equivalent would probably do it, however, let's stick with the O.40.

A lot of motor manufacturers list IC equivalent motor's, simplest is probably E-Flight, good quality, but very "middle of the road" KV wise, if I was to guess, 12-14" prop, ideal as it will need very little throttle for scale flying....so long flight times.

Pricewise, one of the best is Dualsky, Apollo motors are excellent, but slightly more pricey, then some companies offer 0.40 equivalent cheaper end Chinese motors....but they have limitations for some applications, and obviously quality isn't up there....but they may just have one that's spot on for your needs.

After that, you will need most likely a 4s Lipo around 3600mAh, ESC is easy to work out, if the motor is 600 watt, you have 14.8v....divide 600 by 14.8 = Basically 40A, so a MINIMUM of 45A ESC......you then just have to choose BEC or OPTO type.

Once it's explained....it's really quite simple.

[Tim Mackey]

To some people yes....but not everyone can grasp the elecktrickery as easily Scott, yet again however, maybe Steven will reply here now and tell me I am talking nonsense about the difficulties for beginners ?

[scott cuppello]

You are right.....let's see what happens here, I think it's about time we did an IC conversions for beginners thread....what do you think Timbo?

[Tim Mackey]

Good idea.

[Craig Jones]

Im totally lost on this electric subject. Its all so confusing.

1Amp is the same as 1Watt and the same as 1Volt so how can all these numbers be so confusing... - "Got this from online"

I have a motor @ 960Kv so thats 960,000watts, divided by 11.1v = 86486.48Amps so I need a 90,000 ESC?? I dont think so.

The one in the pack is a 25amp

How can Watts = Volts x Amps when there all the same? - "Got this from online."

Arrgghhh my head hurts

[Tim Mackey]

KV is NOTHING to do with watts and amps and stuff really, it is the revs per minute that the motor will turn for every single volt of electricity supplied to it.

The only correct info above is that WATTS is a sum of multiplying whatever volts are present, by the current (Amps ) flowing through the circuit. Volts are set by the battery size.

Amps flowing through the circuit depends on the resistance of everything in the circuit, including the battery itself, and Watts...well see above

Google "OHMS LAW" Craig, and get the basics of this simple law ( the gospel really... ) of electrical physics under your belt and it will become a little clearer

[Mike Rolls]

>>

1Amp is the same as 1Watt and the same as 1Volt so how can all these numbers be so confusing... - "Got this from online"<<

 Craig,

I don't know where you got that from, but it is rubbish. Amps, Watts and Volts are ways of measuing different things - whoever gave you that duff gen might just as well have said 1 pound=1 inch = 1 mph, or the like.

Mike

[Craig Jones]

Cheers for the Info I'll do some more digging around... If only learning about Electric was as easy as learning how to Whitewater Canoe

[Mike Rolls]

Just thought - are you sure he didn't intend to say

1Watt=1 Amp x 1 Volt?

That would be correct, although you more usually see it written

Watts = Amps x Volts

Mike

[Tim Mackey]

Or indeed of course....1A X 1V=1Watt I think on reflection thats exactly what was trying to be said, just that somewhere along the line, "equals" got mixed with "the same as" IYSWIM

[Piper Cub]

Timbo & Scott. Many thanks for your informative answers of the 27. That's precisely the info I was looking for regarding motors ie low kv.

Totally agree about learning small bits of info, anything too large sends my brain into overload!

[Mike Rolls]

One of the problems with starting out in electric flight is the vast range of electric motors and the speed with which some disappear, coupled with the fact that many of them give the prospective user insufficient information. Particularly irritating in this sphere are kits and plans which glibly specify a particular motor (and if you are lucky a prop size), ignoring the fact that that particular motor may well have vanished from the scene.

So frustrating - and so easily overcome. All it needs is for the plan or kit to quote that the YVDRTY 99/12376 or whatever flew this model using such and such a battery and propeller which it turned at (say) 7500 rpm, drawing X amps in the process. Then, long after that particular motor had been superseded half a dozen times, you could still make a sensible choice of an alternative.

Mike

[Former Member]

[This posting has been removed]

[Myron Beaumont]

They've been making them for yonks (alternatives ? )  --  Called an engine !