Ok here's ya another failsafe switch. I haven't built one yet, just cus I haven't got around to it. It is called a phone jack switch. I won't go into detail cus here's enough info to tell ya. I hear good things as well as bad things about these types of switches. So my guess is to use with caution.??.

Here's a couple of threads on rcgroups.com that talk about these types of switches.
Here
Here
More
Last thread


Now here's a site that used to sell the switches but now all they sell are the parts. There's a lot of good pics to give you an understanding of how the switch works too. http://www.hollyday.com/ Under make your own switch jacks.

And lastly here's two links to the products you would need to make your own switch. These could easily be found at an electronics store.
First one
Second one

Josh