Please look at the attached picture and tell which is the correct location to measure the engine to pipe distance.

Thanks.

Jeff

From your drawing, I would measure from the rear of the turbine nozzle to the bottom of the flare (bell mouth) where the pipe is a uniform diameter. This is the "exhaust to pipe" dimension.

Refering to your drawing, measure the "Exhaust to Bellmouth". Typical distance are 3/4" for a P-70 and either 1-1/8" or 1-1/4" for a P-120. (The P-70 has a dual cone nozzle so you measure from the rear of the larger cone.) The dimension is increased for larger engines.

Regards,

Jim

I think it also depends on the shape of the bellmouth - more universal would be measuring year exhaust to pipe dimension.

Jetcat reccommends around 1" from the back of the turbine to the start of the intake of the bell (with their bellmouths that is) (p120 / p160 / p200)

I'm always confused as well

Hans

The answer for that type of pipe bellmouth setup is on page 46 of the JetCat catalog:. Note the catalog is in German and the large bellmouth is not the same as the small bellmouths we commonly see on most ARF jets or from Tam.

http://www.jetcat.de/downloads/jetcatkatalog2009web.pdf

This is from the Flash building manual.
I use this distance on my new jet as well.

There is one more aspect!
You want a loud sound or silent?
Then I all explanation.

Alex

this is how i was taught to set it up

cheers

Duncan

This is all very confusing.

Using a jetCat 120sx with a Smaller Bellmouth (as one that comes with Skymaster kits) I was told to measure from the end of the rear exhaust of the turbine to the front of the Bellmouth and keep the space at 3/4 's of an inch.

From what I read here it appears that the larger Bellmouths are set up differently.

Bottom line is it all depends.

Stan

The Skymaster bell mouth's are more of a little lip an extension of the thrust tube, rather than a bell mouth. unlike an airworld bell mouth for instance, which is huge in comparison.

I threw my skymaster one in the bin and went with a bypass, but still using the 25mm gap between the tail cone and thrust tube. Like you said it all depends on what you have

Jeff, mine on the flash and on the F-16 is like the picture in Duncan's post above. The F-16 doesn't have the big carbon fiber bell mouth like the Flash but the distance on both is right at 1".