ORIGINAL: aussiesteve
Fact is, there is really only one reason that a Throttle kill such as an optokill is ever needed. and that is because of human error (Bad throttle programming, Bad linkage installation, Bad engine installation, poor battery quality, poor receiver installation - the list is near endless on how we can get it wrong on our toys). That video shows me a human error of some sort - asssociated with the throttle setup not allowing the throttle to close completely. Maybe the linkage shifted after takeoff or maybe it was not right in the first place - could be a number of things but they all point to human error of some sort.
As has been pointed out - they don't work on most glow engines.
I prefer to use them on my big toys so as to minimise the engine damage when I make an installation or setup mistake. Having said that, not all of them have got them installed.
My experience is that radio failure (human or electronically caused) will usually result in a ''positive engine stop'' pretty quickly. Or a softer one if the failsafe is set to bring the throttle back to fully closed.
aussiesteve,
If you look at our local regulations(MOP's) you will find that all spark ign engine powered aircraft have to have an ign cutof switch that can be operated by the transmitter to make them legal. I have seen a lot of people turn up at the field with gassers and then have a problem with landing because the engine increases the idel in flight because the engine is just not setup correctly.
Cheers