[bestclimb]

It can be nice when they are way out of sync, you get kind of a vibratory back massage thing going. It works better on freight flights as passengers get worried/whine when the plane vibrates enough to shake their seats.

how about 4 clutched v twins. The clutches could be designed to slip just a little bit with electronic pins that engage when the rotational difference is reduced enough not to shear them or they could be electronically controlled and the computer could closely match RPM then let the pins slip in negating the need for a clutch. The pins and holes could be located so as to reduce harmonic vibration...or what ever. Just begs for straight pipes out the hood, with flappers on them so you know how many pairs are running or nice mufflers under the rig with a set of lights on the dash if noise ordinances get you down.