ESC/MOTOR prolem what did I do wrong?
 

Hi All, I'm fairly new to RC so I guess my problem has come up before and this is the best place to post.

I wanted a Hobby Zone Super Cub with Spektrum radio, ailerons, military paint scheme, brushless motor and Li-Po (I wanted it all right?).

OK so here is 'Egor' the result of my efforts:

[link=http://www.youtube.com/watch?v=FxcFGViDyXs]Egor[/link]

5 flights, I'm impressed it all works well, oodles of power, easy to control, my first model with ailerons and very pleased with the result.

Today flight 6, ooops not so good.

Soon after take-off I lost power, the prop was noticeably stuttering and I brought it in with no power.

The motor, ESC and Li-Po were all very hot, the motor was actually smoking. Since then as soon as I run the motor the ESC and Motor overheat.

So what is wrong? The set-up is as follows:

BL400-15T brushless motor (PKZ4116)

Thunder Power 3S 11.1V 2100mAh Li-Po

BRUSHLESS 20 AMP ESC (PKZ4117)

GWS 10x6 Hyper Drive prop

The ESC, Motor and Li-Po are all parts/combinations recommended for the Park Zone typhoon, so I thought it should all work OK - I was very careful to programme the ESC as instructed for brushless inrunner on Li-Po.

The only major mod I've made to the Typhoon set-up is to use the stock Super Cub gearbox and pinion and the GWS prop.

Any help on where I went wrong or what I should do would be very welcome. I don't know whether to order a replacement motor and/or ESC, change the prop or what to do at the moment, but I do want Egor back in the sky pretty soon I'm missing him! I was very happy with it all whilst it worked!

Many thanks and appologies for long post and my taste in music,

Gemma

RE: ESC/MOTOR prolem what did I do wrong?
 

You probably burned up the motor. The windings can short together from the excessive heat and cause the problems you mentioned.

RE: ESC/MOTOR prolem what did I do wrong?
 

Off the top of my head, I think you blew your motor. If this is the cub I'm thinking about, a guy at my field had the same setup. He lost the motor too. He replaced it with another motor, can't think of what off the top of my head, and has loved it ever since.

If I read the specs on the motor correctly, it's an in-runner? You might have to do some work to get a different motor working. What are the specs on the plane? Or better yet, a link to where you got it.

You may want to post this question over in the electric forums. There they can recommend a different motor for you...

RE: ESC/MOTOR prolem what did I do wrong?
 

So you have the Typhoon motor, but used the SuperCub gearbox and prop?

If so, look at the Typhoon gearbox ratio and the prop it spins. It could be the SuperCub gearbox is not geared down enough and/or you over propped it. I looked at Horizon's website, and they don't seem to have gear ratios for the two gearboxes, but from the photos, it looks like the Supercub has a larger pinion gear and smaller spur gear, which would mean it doesn't gear it down as much as the Typhoon.

I'd get a new motor, and get the Typhoon gearbox and prop. Sounds like you might not have smoked your ESC yet, so wait and test it out with the new motor/gearbox/prop combo before buying a new one.

RE: ESC/MOTOR prolem what did I do wrong?
 

Thanks guys, all makes sense, -pkh- there is a big difference in the two gearboxes, that and the prop might explain it all. I'll go for a Typhoon gearbox and prop as you say and see how that goes unless anyone on the electrics forums steers me in another direction, happy flying :D

RE: ESC/MOTOR prolem what did I do wrong?
 

At some point, if you're going to play around with electrics, you're going to have to get a wattmeter... or something similar. That's the only guaranteed way to know if you've propped your plane correctly, if your battery is up to snuff, and a host of other parameters that have to be right for an electric to fly. You've stuck with a proven combination, which is good, but it's not proven on your plane.

See if you can find a buddy who flies electrics and has one of the above mentioned meters. Will tell you more in 10 seconds than a week of guessing....


A

RE: ESC/MOTOR prolem what did I do wrong?
 

Once you let the magic smoke out of an electric motor it is pretty much time for a new motor.
The smoke is the insulation on the windings burning off. Once that happens the motor has much less resistance and will act like a short causing everything else to overheat.

RE: ESC/MOTOR prolem what did I do wrong?
 

Hi guys, thanks for the replies I get it that the motor is now an ornament, I'm now looking to go again but this time get it right and not cook another. I posted on the electrics forum also at: [link=http://www.rcuniverse.com/forum/m_7064141/anchors_7064141/mpage_1/key_/anchor/tm.htm#7064141]clicky[/link]
As I've said there I have a wattmeter (see I learn quick eh) but alas wouldn't have a clue what I should be doing with it, how do I know what is an acceptable current draw for a particular battery/motor combination, I don't know where to start [:o]

RE: ESC/MOTOR prolem what did I do wrong?
 

Yep, a Wattmeter is an excellent investment if you want to fly electrics. They are about $50, but it will pay for itself if it saves you from smoking just one motor/ESC/battery setup.

RE: ESC/MOTOR prolem what did I do wrong?
 

Your motor, ESC, and battery should all have max current draw ratings. If your current draw exceeds your limit with a given setup, you need to try a smaller or lower pitch prop, and/or you need to gear down the gearbox some more. You said you had a 20A ESC, so at a minimum, you need to limit your current draw below 20A. See what the max continuous current draw is for your battery pack, and see if you can find out what the max continuous current your motor can handle (not sure if you can find this spec for the Typhoon motor, though). The component with the lowest continuous max amp rating will be the limiting factor.

RE: ESC/MOTOR prolem what did I do wrong?
 

Ta -pkh- I get the idea, I've a new motor and Typhoon gearbox and props on order, as this is all stock stuff I can run it on the bench with the wattmeter and get some guide numbers and make sure it isn't drawing over 20A this time, I've a feeling at full throttle I was exceeding that by a huge margin with the big prop and cub gearbox. I feel a bit dumb that I had the wattmeter there all the time but hadn't taken the time to find out what to do with it, cost me a motor, but I know better now ;)

RE: ESC/MOTOR prolem what did I do wrong?
 

The big problem with electrics is all the variables that have to be considered. And if they are not, then you find out that the result is usually smoke from that expensive shiney equipment.

There is a web site that has parameters concerning watts per pound or ounce (whatever is applicable) to find the right combination of engine/prop/ESC that you need for a particular plane. I cannot remember that web site but I will try to find it. A little research here on RCU will probably get you there though.

The point here is that no two are exactly alike, although if you get one particular airframe, the recommendations by the manufacturer will work just fine. If you change any of these items, you will probably have to recalculate how that change is going to effect how that combination works out together. Even changing a prop can have adverse reactions with the motor/esc combination. The worse, of course, is over-current through the ESC, or a motor that is incapable of handling the wattage requirements for that change.

In a nut shell... do you homework. :D

Quick note... P = I x E

P = W = Power or Wattage.. watts
I = C = Current or amperes.. amps
E = V = Voltage.. volts

The voltage of a three cell LiPo, for instance is 11.1 volts, so that is a constant (well, almost, but for all practical purposes here, it is). That means that I or current varies with the demand placed on the motor by the weight, drag, speed, and so on, of the airplane which is controlled by the pilot. At full throttle, the power (Watts) should never.. NEVER exceed the maximum capabilities of that ESC and motor combination with the prop of choice.

So, if something says 200 watts, then you have 11.1 volts X 18.01 amps = 200 watts. The requirement here is 200 watts. So, varying the current with a constant voltage will do the trick as long as you maintain 200 watts. If the requirement says 200 watts per pound and you have a two pound plane (everything.. motor, ESC, battery, servos, RX, airframe..everything) then you will need 400 watts or an ESC and battery pack that can yield about 40 amps and a motor that is also capable of handling a load of 40 amps.

In other words, use the wattmeter!!

CGr

RE: ESC/MOTOR prolem what did I do wrong?
 

Thanks to all, I hadn't realised CGr what a can of worms I was opening by putting a different motor in the front of a HZ cub (believe me I really should have known better).. but I've googled and found much help on theory of electric models and started doing my homework. I was destined to fail with my original approach, good job I posted my beginners question and got steered in the right direction instead of just putting in another motor and watching it go the same way as the first! :D

RE: ESC/MOTOR prolem what did I do wrong?
 

According to the specs for the motor the prop you used was too small. Horizon specs the prop size: at 13.5 x 7 and 12 x 8.75 . Try it again, use a different prop and a Watt meter. Remember 20A is the limit at full throttle.

Happy Landings!

RE: ESC/MOTOR prolem what did I do wrong?
 

THats why I prefer glow, all these electronics are very confusing.[X(]

RE: ESC/MOTOR prolem what did I do wrong?
 

There is a learning curve, but for park flyers, electric is really the only way to go IMO.

I still prefer nitro for larger planes, but if LiPo battery prices come down in the future, that may change.

RE: ESC/MOTOR prolem what did I do wrong?
 

Not quite.

What you said would be true if he used the same gearbox/gearing ratios, which he did not.

RE: ESC/MOTOR prolem what did I do wrong?
 

LOL no wonder you guys have a thread where you all think that girls don't fly R/C - would it be easier if I spelt it out GEMMA ... I fly the ones without a TX and RX also just for the record when the WX allows me to in the UK ;)

RE: ESC/MOTOR prolem what did I do wrong?
 

Please forgive our ignorance. Here in the US, Gemma is not a very common name, in fact I've never even heard of it until now.

RE: ESC/MOTOR prolem what did I do wrong?
 

Same here [sm=71_71.gif]

RE: ESC/MOTOR prolem what did I do wrong?
 

Wow I didn't know that it wasn't a common name in the states, it's pronouced Jem-ah the more common spelling in the UK is Jemma. Just use my middle name then of Jane, I know you will have heard of that ;)

RE: ESC/MOTOR prolem what did I do wrong?
 

good news! Egor is back in the air with a replacement motor. More newbie questions!

It turned out that fitting the Typhoon gearbox was a non-starter. It just won't quite fit the cub firewall and allow the cowl to go back on. Also the Typhoon props are way to big for the model. This led to me using a cub gearbox again with GWS 10x6 Hyper Drive prop. This time though I checked with the Wattmeter and as most of you probably realised it was possible to draw way over 20A. My solution, a bit of a cheat was to use the DX7 radio to reduce the throttle throw to 40% and now it can't draw more than 16A at anytime.

The flight was great, still nice lazy rolls easy loops etc so I have the semi-aerobatic aileron trainer I wanted.

Now the questions, lets assume now that I'm sticking with the motor, the gearbox and battery, it seems to me that the only variable left is the prop.

I would like a smaller more scale prop, am I right in thinking that downsizing the prop will mean that I can use some of that 60% throttle I've dialed out? I.e. will a smaller prop mean less current draw?? What are the obvious advantage or disadvantages and the effects of diameter and pitch?

RE: ESC/MOTOR prolem what did I do wrong?
 

If you are drawing too much from a motor, a bettery way of doing things is to merely use a smaller and/or lower pitch prop as you surmized.

On an electric using the end point adjustments prevents you from calibrating the ESC, and you may find that your ESC will compensate for the less throw anyway. In effect it tries to "undo" exactly what you've done.

Diameter corresponds to how much pull you get from the motor, while pitch corresponds to how much speed you get out of the plane.

You may want to try say an 8x6 prop. or 8x4 or so.

RE: ESC/MOTOR prolem what did I do wrong?
 

Ta opjose, I've ordered a whole bunch of props of different sizes and pitch so I can experiment a bit and find the best combination, I'm hoping that way I can find one that is just right. I'm using GWS props which here in the UK are inexpensive and with a little bit of work with a reamer fit the stock cub gearbox well.

RE: ESC/MOTOR prolem what did I do wrong?
 

Ah yes.. my Venus II with an OS 1.20 AX and a 15-10 prop. No brainer.. :D (but I DO have a few props of different size and pitch just in case I want to experiment, but so far, the 15-10 has proven to be the best).

My point here is that you will probably find that in your experimentation that one prop will stand out as the best performer at the least current (in my case, the 15-10 was that prop, and this is true with both glow/gas and electric). This is possible, but you also gotta be careful because if you are not careful, a short excursion beyond that max current point may cook both your engine and ESC.

With glows, you try to attain the best operating performance at the best RPM. There is no current draw issue.

With electrics, you are trying to optimize performance at the best current draw and wattage consumed for that motor-prop/esc/battery combination. It isn't easy, but as one said, once into that learning curve, this stuff begins to make sense and you can almost predict what prop will work with your selected hardware combination. RPM are usually set by the KV rating for that motor.

Just be careful with that. And remember.. those props can be a tad dangerous on electrics. With glow, if you put something in the way of a rotating prop (like your finger), it will usually stop (it will do damage but it will most likely stop). With electrics, well, as long as there is an electrical connection with current supplied, that prop will try to continue turning no matter what's in it's way.. fingers included. I've got the 5 stiches on my rigth index finger to prove it.

CGr.