PLANE JIM

My Feedback: (109)

I am new to electrics and having a blast with them-I am having a problem with one airplane-I do not own any voltage meter or amp tester-so I am trying to figure this out as a best guess-pretty scientific -I am a old gas and glow flyer-I have super impress by wattage with a cobalt 27t motor and a 1950 nimh pack with a jetti 30 esc-the motor started a slow surge at high throttle two flying sessions ago and during the flying session I pulled the throttle off to glide down and when I went to throttle back up nothing happen-controls work fine and I figured it must have shut down due to low voltage-charged it backed up later that day between other models that i was flying and it would not run again-took it home removed engine reciever and battery and esc and saw nothing wrong-reassembled and it worked fine on the bench-took it out to flying field today and flew one flight and it flew well-landed and recharged after flying several other of my glow models and on this take off it seem to have a weak battery-I limped it around and on short final the motor stopped and all controls still worked and I deadstick. check for a false peak of the battery and the battery was still nearly fully charged-I took another battery out of my electric playboy and the engine would not power up-what do you think it may be-the brush 27t cobalt motor worn out, the esc-I think the battery is good due to fact the battery is less than 2 months old and when using a seperate battery I was getting the same results-I really do not know how a bad esc behaves-and I know little or nothing about electric flight-if you have a thought please let me know -thanks jim

Bumstead

My Feedback: (2)

First thing I would suspect is the FET's in the ESC, the BEC seems to be working OK as you said
you had flight controls during the motor run problem.
Next would be to check the battery connectors. If they are flaky, it may cause problems with high draw motor
running but past enough juice to operate the receiver and servos.
It is just a process of elimination and careful check of your connectors

PLANE JIM

My Feedback: (109)

I appreciate the advise Bumstead-what is a FET and the connections look good-I have dean ultra connector at the motor as well as the battery connection-maybe I need to look at the connection into the reciever at the throttle -I will let you know -thanks

Matt Kirsch

My Feedback: (21)

Hold on, hold on.... No need to start freaking out checking all kinds of weird things. 99% of the problems are simple, obvious issues.

The pulsating motor is NORMAL. Jeti ESCs pulse the motor up and down when the battery is running out of juice to let you know that it's time to land.

Wattage Super Cobalt 400 motors have... issues. In short, they're not that great of a motor. Your problem is probably just a stuck brush, or worn out brushes in general. This is a high-RPM motor with very soft brushes; they wear out quickly.

One other thing, a tip for future reference: You can't tell how charged a battery is by just measuring the voltage. It will be 1.2 Volts You can only get a rough idea of that by recharging the pack on a computerized peak charger with a readout of mAh.

PLANE JIM

My Feedback: (109)

I appreciate the advise-the motor was not really a pulse it was just a small change in rpm at full throttle more of a surge - I am using a mrc super brain-I do not pay much attention to the readings but I got the same result with a known good battery fully charged as far as not knowing how to charge a battery in reference to reading voltages -I am new to electric flight not gas or glow flight which I have been doing for a little while -I think I will run it over to new creations r/c in the am and let them check it out-thanks

Matt Kirsch

My Feedback: (21)

Lucky for you, you have a top-notch electrics vendor in your area. Did you get a chance to have it checked out yet?

Surging... That's exactly what the Jeti does. It's not a full on/off cycle. Poor choice of words on my part...

threepointlanding

I’m having and issue with the Super Impress myself. Not the plane or the ESC, but he Colbalt motor that came with it. I have to tap the motor to get it to fire up, and I really don’t think I’m getting full power with it. I’m using a 30amp esc, and a 1300ma prescribed battery. I took it out today and it did start, but more or less limped around the field. Took the nose off when I got home and ran it around the cudasac a bit. It did much better, with my TAPPING the motor every once in a while with a screwdriver handle.

What’s up with that….are the Colbalts POS’s or what? Should I just replace the motor with a different one? Any other brand anyone might suggest? I’m used to the power of the nitro engine, and this is a bit of a disappointment to me.

At first I thought maybe it just needs to be broken in, but now, with the tapping, I don’t know….sounds like a piece of crap to me.

Just want to fly the thing…

threepointlanding

Let me correct myself and say Cul-de-sac…lol…

The other thing I wanted to add is I don’t want to invest the money in brushless motors at this point. I have too much wrapped up into nitro to head the other way. I just wanted this as a Sun morning flyer.

Cul-de-sac

Matt Kirsch

My Feedback: (21)

Again, sounds like a stuck brush. When you tap, the brush will drop in and make contact for a while. As you run the motor, the brush wears back and begins to lose contact because it's not sliding down in properly. This is where you see the loss of power. By the time you stop, the electricity is jumping the gap, or close to it. The motor won't restart because the brushes aren't making good enough contact.

Take a look in the brush holders. Is the spring way down in? Carefully lift the spring out of the way and remove the brush. Does the rounded surface look burned? How much brush is left?

As I said earlier, the Wattage Cobalt 400 has... issues. I've got one and it's a little screamer, but the materials its made out of are not up to the task of screaming for long. You might try replacing the brushes, maybe having the commutator turned at a local R/C car shop...

I'm trying to think of a brushed option that will give you something close to the performance you were getting from the Cobalt when it was new. A 7.2V Speed 480 motor is a drop-in replacement physically, but it's not quite on the same level performance wise. Other cobalts are as expensive as brushless...

GWR

My Feedback: (31)

The Wattage "Super" [:'(] Cobalt motor is garbage. Don't want to go brushless!, AstroFlight and Maxx Products have cobalt motors that really perform well.

Matt Kirsch

My Feedback: (21)

As I said, though, the Astro and Maxx products cobalts are just as expensive as brushless, even more so:

Promaxx Cobalt "400 size": $69.99
Astro Cobalt 05: $99.95 (not really a fair comparison, a much bigger motor than the 400 class)

Himaxx Brushless 2025 "400 size": $52.95
Astro Brushless 020 "400 size": $79.95
Eflite Park 400 Brushless motors: $54.95 - $69.95

The Eflite 20A brushless ESC is $41.99 at any hobby shop, so the bottom is really falling out of the market on this stuff. It's not so expensive to go brushless anymore, and with major players like Great Planes and Horizon getting into it hot-and-heavy, it's only going to get less expensive as time goes by.

threepointlanding

Well, turned the motor 2/3 degrees and that seemed to help some....but the motor just has no power....got it up, and it just rolled over and dove.....lost air speed....guess I should have stayed on the runway for another half hour or so...till the ground speed came up...lol...

So here's what we're doing.....the crash took down the firewall and popped the motor out....everything else is fine.....

I'm rebuilding the fire wall with stronger materials, and going to mount a nitro engine on it...switching radios to a standard 4 channel rather than the GWS radio..this way I get a throttle servo in there...

getting a small tank, and a light batt pack.....

Gonna see if we can get this thing to fly correctly......"on nitro"...lol

Would like to put a .25 or so on it....but...........i have an older os40......and stik landing gear....."Frankenstien time"...