There have been a number of them over the years all the way up to about thirty feet (those were sold for commercial outdoor advertising. Most have been the indoor variety and were filled from small party balloon helium bottles. These were operated by very light twin fan electrics and had there own dedicated radio system which is very inexpensive but is the reason you could not use your own radio.

Sorry I have not url's but these things are advertized frequently in RC and general interest magazines under various names. I think polks sells a version.

John

I agree they would be great fun in the house to drive the cats crazy untill it would not lift anymore from being overweight caused by all the scotch tape claw patchs.