http://turbo-pyro.s3.amazonaws.com/Making-a-Girandola.pdf The spinning is just for stabilization it doesn't provide lift, which is what I thought when I first saw this.
Uh-oh!! The mad canuck is going into the pyro experiment business. All you northwesterners, take cover!!
I know of no reason why the center section could not be a fan blade and add lift to the rocket motors, as well as stabity.
Agree, tho' it would add drag after the spinner motors burned out. Could possibly compensate for that with a bit more tilt to the lift motors.