The Vomit drive, so called due to the unfortunate side effect of having the main section rotate out of sync with the rest of the craft, inducing travel sickness. As far as I know it is the first of its kind (and may be the last!). The craft works only by using angular momentum. The sas unit is on a bearing with allows it to spin, which in turn rotates the crafts main section through angular momentum. No drive parts are connected to each other.
Shortly after creating the vomit drive, Kerbins finest engineers called the drive pointless, before calling it the work of the Kraken as well since it seemed to work by magic. Eventually its creator, Erasmusguy Kerman was banished to Eeloo!
https://kerbalx.com/erasmusguy/vomit-drive-warning-might-make-you-feel-sick for the craft file.