Gordy62

Hi,

I've just about set to test fly my Raven from Hobby Lobby. I may have a problem with the ESC; perhaps some experts out there can provide an answer.

I bought the whole Raven package from Hobby Lobby (Tx, Rx, ESC, servos, etc.). It uses a "JETI ADVANCE 18 plus" ESC. Here's the problem (assuming it really is a problem):

While testing system response, everything seems to work just fine up to a point. However, after the motor (Uberall "Nippy Black" 1812/100) has run for several seconds and is throttled all the way back until it stops, the motor usually won't restart without cycling the receiver/servo switch off and then back on again (very difficult to do while a plane's in flight). While the motor's running it responds perfectly to speed commands. For power, I'm using a 1500mAh 3-cell Li-Po pack. I have a 2600mAh PolyQuest pack on order, which should be here any year now (couldn't get it through Hobby Lobby).

So far, all testing has been with no load on the motor (propellor not installed). Can this have anything to do with my "problem?" The recommended Graupner prop adapter is not sized properly since less than a single thread on the adapter shaft remains after the prop and spinner are installed. I ordered two other types of adapters, and they just arrived today. One uses a constriciting collet to hold the prop and spinner in place, and I'm certain it will work well, but I have to run out to get a reamer to enlarge the hole in the prop hub.

Until I get the prop installed and test things again, I have no way of knowing if a problem actually exists. But, the way my luck runs, the problem will be still be there. In the meantime, can anyone gives me some clues as to how to solve my "problem?'

Thanks,
Gordy

Matt Kirsch

My Feedback: (21)

You really shouldn't be testing the motor with no prop. With no load, it could overspeed and sling a magnet. The prop also acts as a sort of flywheel, giving the motor momentum to send a signal back to the ESC. The ESC needs these signals to tell which way the motor is turning, and when to send the next electrical pulse to the motor.

The only possible cause for your problem that I can think of, other than possibly the lack of a propeller, is a faulty ESC. How do you fix an ESC? You probably know more about it than I do... With the tiny surface mount components and a lack of schematics or programming information, it's pretty much a given that mere mortals like us can't fix them.

wreck_em_all

With all due respect to "Electrifying Moderator" Matt, I run my BL motors without props during setup quite frequently. The ESC samples motor BEMF ("giving the motor momentum to send a signal back to the ESC") with or without a load (propeller). A BL motor can't overspeed as it's speed is governed by the ESC, the motor does tend to slow down under load. Running with or witout a prop only imapcts current draw. "Inrunner" motors do not have magnets to "sling off" the magnet is the motor's rotor. Outrunner motors have the magnets glued to the motor casing. Glue and centrifugal force hold the magnets to the casing. Only a catastrophic failure to the casing would allow the magnets to fly off. I have had magnets come loose due to cold temperatures, and I assure you they didn't fly anywhere. They did make a mess and nasty grinding sound.

I can and have repaired BL ESC's including a number of Jeti's. If you are interested, let me know.

Gordy62

Hi,

Thanks for the advice on my ESC "problem." All's well now, it runs fine with the prop installed.

I have a real complaint though. I just spent at least 45 minutes composing a lengthy post in response to Matt and "Wreck Em All." When I hit the "OK" key I got a message that the post was undeliverable, something about not directly accepting posts. No previous warnings, no nothing. Apparently all my effort went up in smoke. "Thanks a lot" to someone for wasting a good part of my morning!

Gordy