hooked my lines in long grass on takeoff in the weekend - plane turned in then prop struck the ground - next thing I know the nose of the plane is on fire...

I had the ESC to "Very Sensitive" on the overload - and this still happened - I thought it was supposed to be an instant shutdown?  

Luckily my launching buddy got there and whipped the battery out before that caught on fire too.....

the plane was OK other than smoke damage - motor and timer and battery are all fine - just need a new ESC!!

I haven't torn down one of Castle's controllers, but I suspect that they don't do the cycle-by-cycle current limit that you would need to achieve this.  To do so takes some extra circuitry (little dinguses called comparators, some current sense resistors, and some logic gates), a controller chip with hardware that knows what to do with the signal if a comparator notices that the current is over limit, a moderate amount of some hardware engineer's sweat poured out in the development lab, and software that knows what to do when the controller chip shuts things down.  When you're all done adding that, if you use a motor with too low of an inductance or if you get a short circuit at the ESC output then it all goes up in smoke anyway.

That more-capable controller costs more, may be bigger, and may consume more power.  The other extra circuitry certainly takes up space, adds cost, and robs a bit of power.

I'm not trying to apologize for Castle, but -- out of curiosity -- how much extra would you spend in money, size, and weight, for a controller that's guaranteed to not go up in smoke in the event of a prop strike?

ESCs has usualy thermal limiting cut-offs, but they are too slow for such case and they have sometimes also current limiting, but it is also not enough, because such thing can happen as result of dissynchronization (FETs open without back EMF = immediately damaged FETs). Aditionally such thing can happen also as result of overvoltage - both motor and also battery with its leadouts are inductions, so any erratic run can lead to overvoltage on FETs. The result is damaged FET transistor and ESC cannot prevent burning as it does not have backup switch which can disconnet FETs from battery. So 100% good solution will cost too much (amoney and space) as Tim wrote.

However there is one wery simple and well working solution - do not tighten the prop nut too much - so when it hits the ground, the rotor can move futher so ESC has time to react. ... tested many times with success :-)

Wouldn't a pusher help with a "do not tighten the prop nut too much" solution?  Wouldn't it tend to tighten prop nut so that it won't come off under normal operation?

      

I wonder if you were purpose-designing it if you could make an overrun clutch that was more reliable than a prop nut that's tightened just so -- perhaps a collet with a steep angle and a locknut, to hold the setting?

Or maybe just tighten the prop nut just so, and don't try to put all that extra weight and expense into a mechanical part instead of the ESC!

The Castle Creations Pheonix esc line is no where near as sensative to this problem as the ICE esc's are. Having gone thru 3 ICE (2 prop strykes, one doa) I asked and CC's replaced the ones under warranty with Phoenix's. I will not use an ICE any more. Too much risk of a problem.

bob branch