How much bigger than this do you want to get?
[link=http://www.google.com/search?hl=en&q=fire%20scout&gbv=2&gs_sm=e&gs_upl=1 890l4672l0l5219l10l8l0l0l0l0l0l0ll0l0&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi]Google Search Fire Scout[/link]

Notice it is a Department of Defense Project. The goverment might not look at you kindly if you attempt this in your backyard.

Rafael