Stan

Here goes with the pics any more dimensions just ask, the plywood spacer I used was 1/8" and I did turn a plug up to get the correct centre with the carbon bell mouth entry etc...

I noticed you state you don't want to use packing but I found on mine if I used the 1/8" everything inline plus the Hawk flies spot on with no pitch change whatsoever with any throttle settings. The way I did it was the ony way with the carbon shield that gave me what I was looking for.

The tube exits the fus by 5-6mm.

If you set up the engine to the settings then using a plug say plywood for diameter of the bell mouth and balsa (both centred and glued together) to fit exhaust of turbine that will allow the centre height of the thrust tube.

Just noticed for a second time the JetCat rubber disc that holds the JC fod guard in place the rubber has perished/rotted again.... won't be buying a third will get some decent rubber sheet and make my own []

Alan