< I was under the impression that a prop strike in the grass would shut a motor down on Very Sensitive setting.?? >

Well, now you know that is not always true!!   

I have had an inverted "touch and go" where both blades of the prop were sheared and the motor continued to run (with just the hub) until the timer button was touched. Sensitive setting or not things can go wrong and your ESC may not save the day. 

When you design esc's it's not a simple matter to allow it to handle the huge current that we all fly with and then make it shut down when the prop strikes the ground. This is why I made my governor timer use a low rpm trigger point to stop the motor. I monitor the rpm all the time with an extra wire from any one of the motor wires, so this was a simple thing to add on. The system does need to get over the slow start up and into governor mode, so in long grass I always suggest that you get someone to hold the model until the governor kicks in.......about 2 seconds. After burning out 3 very expensive esc's, with the last one due to jamming the prop, I was determined to prevent this happening. My system allows governor with low-cost esc's, so now I can also be a "tight-wad"!

Keith R

Hi Paul,

Insulated lines are fine for scale or carrier models, but do not work well for stunt..........especially having 3 lines. It also complicates the handle. My system needs a motor wire pickup and this wire needs to be relatively short otherwise it could pick up added noise, so there are many negatives in using signals down the flying cables.

Keith R

I can personally testify that Keith's system does infact shut down before damage is done to the ESC, battery or the motor.   Before using his timer I smoked all three in one accident in grass.   I have gone on to proved this a couple of more times, some people are just accident prone!
Andy

Hi All,
Rules aren't the issue: the drag of insulated lines is death to being able to fly Stunt properly.
It really is that simple.
Hi Dennis, I hope the ship isn't too badly damaged. Yours sounds just like what happens wet: chased around the center of the circle by a plane with half a prop ... I've been there, but I was younger and faster, back then! Frangible wood props might help.

The current limit sensitivity does not change the limit current to a lower value: sensitive just means that the overcurrent event doesn't have to be as long or dramatic to cause shutdown. 
As we see in another thread, having a current limit that is too low that activates quickly and suddenly can cause the loss of a plane during the high current vertical climbs.
take care,
  Dean P.

If you go to the trouble of adding a radio system why not throw in a couple of servos, cut the lines and set it free.

The couple of scale guy's I've seen use standard lines and just brush on a layer of urethane. Can't be that much of an increase in drag.  I've used U-Tronics on a 1/2a size plane by attaching 36AWG magnet wire to my lines and hardly noticed a difference.  It might take some experimenting but there are ways to minimise insulated line drag.

I'd be nice if Clancy and Keith got together so we could use a U-Tronics handle to control Keith's Timer in the plane.  Then you would have pilot control to start and stop, RPM governor, adjustable govenor gain and prop strike protection.

Addendum - I just spent a few minutes googling for some PWM switches or relays.  I think I just found a Summer project.  I'll try a PWM relay to replace the KR Timer slide switch.