Do brushless motors need breaking in?

[zeta30]

After about 8-10 very happy flights with he brushless set up the motor fried. Don't know how or why. I rarely pushed the throttle over 1/2 and had a 25 amp Phoenix ESC. I am assuming the ESC was large enough because the Typhoons come with a 20AMP.

The motor was so fried that it was completely seized and still smoking when I landed.

I'm so happy that the SC does so well gliding because I was able to get it safely to the ground with out a scratch.

I may give up on the Typhoon motor and go with a tested and known good out runner like mrmugen has, an E-Flight 450. I'll have to think about it since this was the last nice day we will have for a while.

[duck9191]

i wounder if a bearing failed causing it to stop dead and over heat.

[flydiver]

Not only balance but probably prop down and use a different prop if you are using stock. You've gone WAY up in power and RPM's. If you are using the stock PZ prop (or something else the same size) it is too flimsy and too low quality for this application. The increase in RPM's puts a serious load on the motor trying to push a prop that is too big. I suspect that is what fried the motor. The 25A ESC merely allowed the power to keep going to the overloaded motor. The only way to be sure is know the rating of the motor and test the load with something like a Wattmeter.

A "cheap" field method is to fly the motor hard for 1 minute, land it fast and test the temp. If it is too hot to hold you are overloading the motor. You can bench test the same way but limit full throttle to 30 seconds.

Re-windsurfing: I agree a good day is 25-30. How often does that really happen? I find a good solid 25+ less than half the time. RC is filling a nice hole on quiet mornings or those hot "skunk" days.

fly

[zeta30]

Thanks flydiver

25-30 winds on the weekends were pretty rare this year. Last year had a ton, I don't think I sailed on anything larger than a 4.2m sail last year. This year I didn't use anything smaller than my 4.7.

I was talking to a guy at a LHS. He said the same thing you did about the prop and size of prop he also said another contributer to the fried motor could have been the change in the gear ratios. I went from a fairly small gear that was on the motor when I bought it to a very large gear that is on the stock brushed motor and from a medium sized gear that is in the Typhoon to the smaller SC gear. This put extra strain on the motor too.

I did switch props on your suggestion before the motor fried, I went to an E-Flite 10x8. I didn't get the vibration but I guess I should have gone to a different sized prop.

[flydiver]

Later after I wrote that, I wondered if you had changed the gearing also. It didn't make sense to me in the beginning. I thought move volts = more power > bigger prop. I understand it's the reverse now (sorta-depends on the KV of the motor, gearing if used, inrunner/outrunner). The cub is basically a brushed inrunner geared down a lot (3:1 I think) to swing a big prop. If you put on a higher KV (RPM) motor you either have to gear down to the equivalent amount or prop down to compensate. As you increase voltage you have to do the same thing. Heat is the clue. Excessive power not utilized properly rapidly becomes heat.

Note-just checked the Typhoon specs. That motor uses an 8:1 gear ratio, WAY WAY lower than the Cub.
I think the motor is (OK-was) probably this:
www.e-fliterc.com/Products/TechnicalSpecs.aspx?ProdID=EFLM1105
That's a 3700 KV, 20A motor. I can swing that big prop because of the super low gearing. If you geared it up, well, it burned up. Used in direct drive a motor like that would be turning a 4" prop.

The E-flite is a better quality prop, not really a noticeably more efficient one. I personally think the stock prop is kind of expensive and flimsy-a poor value. You probably needed something like a 9x5 APCe/GWS-HD, at least to start and figure it out. That's where a Wattmeter helps once you understand them.

Second note: Make that an 8x4 or 8x6 to start if you try that again.

A big outrunner is subject to the same physics. Make sure you know how to power and prop it.

The Gorge can be funny. I had one year I thought I was going to wear out my 3.9. This year my first 3 trips (all 4-5 days) usually got me about 2-4 hours of sailing-total, often most of that was pretty poor quality (gusty). Last trip of the year was finally nice. Oddly, I also got in the best flying.

It's a lot like sorting out the right board/sail/fin combo for the wind and wave action. Part science, part art. In sailing feedback is getting slammed or schlogging. In RC it is not flying well or burning up your electrics.

fly

[zeta30]

The only specs I could find on the motor is that it was a 4200kv motor. I did a bunch of research after it burned up and no one seemed have any other specs than that.

I'm thinking about going with an outrunner this time. Probably an e-flite 450.

We were due for a bad year in the Gorge, I think this was the first really bad year in about 5 years. I only sailed 5 times this year, the fall East wind days really sucked too this year. (at least on the days I was able to get up there)

[flydiver]

This motor is just as powerful for about 1/3 the price:
donsrc.com/cart/index.php?act=viewProd&productId=6
Got a buddy with one. The "Don" is fine to do business with.

The e-flite 450 is great if you want to go with a known brand. I've got a 400/740KV and it's a fine motor.

If you had the 4200 that is even more of an issue. That needed some serious low gearing, 6:1'ish.

About 15 years ago the Gorge went through a period where it was basically windless for 13 weekends in a row. Blew mid-week just fine. For a lot of people it was a skunk year. For me and my buddy it was a good one since we do long "weekends". Not worth the drive for us for 2 days. Now it's even worse with gas prices. That's one of the things I'm liking about RC-I'm 1 mile from a good flying site (Magnuson Park) and I have the 520 bridge sensor to tell me if it's flyable.

fly

[zeta30]

That is a great price for the motor. Too late though, I already picked up the E-Flite on my way home from work though. I'll post pics once I get it together.

Man, you're an old timer to wind surfing... I am too though. I started Gorge sailing in 1984, back then I lived in Vancouver, WA. One of my buddies and I were one of the first people to windsurf in Vancouver Lake. There were only about 4 of us back then on the lake.

I think I remember that year when it was so bad.

That was about the time I was sailing pretty frequently at Jones Beach in Clatskanie. I used to sail with a couple of engineers from Seattle at Jones. I remember it was pretty busy around then because the Gorge "wind snobs" were sailing in Clatskanie instead of the Gorge.

That was of course before all of the Gorge real time wind cams and I-Windsurf. The new windsurfers don't know how good they have it.