There is a whole industry being built around turbines, ducted fans and electric ducted fans.
One of the practical turbines for control line would be the Wren 44 with 10 pounds of total thrust. The thing is not much bigger than a soda can.
Look at it at
www.wrenturbines.co.ukor at Jet Hanger below
Larry Wolfe of Jet Hanger is a distrubutor here in the States at
http://www.jethangar.comJet Hanger also has a complete line of fans for gas and electric. Much of what Jet Hanger has can be adapted to control line use and Larry would be helpfull in getting started in the right direction. There are others out there, but some of the material that Jet Hanger has is more adaptable to control line than some of the other product lines/distributors. The pace of developement, particularly with electric ducted fans is short of amazing.
There are also several great magazines devoted to the jets.
Jet International is published by-monthly in England.
Jet Power is published quarterly in Germany and prints in English.
www.modellsport.deI have the Wren 44 and a Jet Hanger F9F Panther kit that will be built someday.
Keith Trostle