Let the hive mind of Engadget get that for you.
"I commonly need to boot a system from an external disc and take a snapshot of the host system. I also then need to burn a copy of the image to a DVD. While I can do it with two separate external devices, and two power supplies, and two I/O cables, it'd be nice to find a small dual-drive enclosure. It would need to have USB, eSATA, and FireWire. Either slim-line or half-height bay for the optical burner would be fine, and space for either a 2.5- or 3.5-inch hard disc. Any ideas?"
Indeed the rotors slow down and from what I understand you can land safely.. The only time I see any use for this if the engine stopped and froze the rotors, and if that would happen I dont think some airbags would slow that thing enough to save any lifes.