Adrian,

Being an old heli flyer, I must disagree with your post too. (What a pain in the &%/¤ that fwahlgren) .

I have had a X-Cell 60 with a U shaped pipe and a Robbe Futura 60 with a straight pipe. Both of them you had to work with the manifold length to adjust were the pipe set in. Of the two helis the futura had the most "pipe effect" characteristics, hence once reving above a certain rpm, the engine went crazy and continued to accelarate even though you eased of the throttle/pitch stick. It actually was a bit tricky. Of course the Robbe had the OS 60 FX WC heli, which was OS most powerful heli engine then, putting out a whopping 2,4 hp. The X-Cell had a OS60N (?) or sometehing, their more affordable version, which made it a bit more moderate in handling.

I have also had a Kyosho Concept VR46 without a pipe and all I can say about flying non piped helis is: boring!

The conclusion is that pipes truly helps raising the effect. Check out Bollys home page, or weston, or som of the others and you will find some info about pipe theory.

Sincerely
/Fredrik