BCoston

My Feedback: (7)

What distance should the bellmouth of my pipe be from the tail cone of my Simjet 2300?

Darryl Usher

It all depends on the diameter of exhaust and the diameter of exhaust pipe. And how well your centered. Exhaust comes out with about an 10 degree spread all around.
Darryl Usher

Vampire

My Feedback: (2)

BCoston,

The forward edge of the bellmouth inlet of the pipe to the discharge opening of the engine exhaust nozzle should be FLUSH to no more than having the exhaust cone .25" inside the inlet.

As Darryl stated, the raw exhaust gases will not impact onto the pipe until 4>5 inches or so down the pipe from the engine exhaust nozzle. You will see this by the coloration of the pipe after your first run.

I have a 3.5" Inlet with a 3.25" dia. discharge diameter on my 2300 in the SkyRay and it is approx. 23 > 24" long. It works very well.

Tam Jets is another excellent source of information on the purchase and sizing of tailpipes.

Brg.

BCoston

My Feedback: (7)

Well, now I am confused. I had read most turbine have a distance of .5" - .75" from the tail cone of the turbine to the forward edge of the bellmouth. I have a simjet 2300 that has a tailcone of 2" diameter (factory cone). The pipe is one from skymaster for an f-18C. You guys are suggesting I mount the pipe so that the exhaust cone of the turbine is flush with the pipe or slightly inside of the pipe. Is that correct?

Darryl Usher

The exhaust does not start at the bellmouth. Draw a side view, start with two lines 2" apart.
This is your exhaust, angle a line up 10 degrees from your top line, do the same for the bottom but angle it down. Where the angle lines match the diameter of your pipe that is the distance
turbine exhaust is from the pipe.
Darryl

Vampire

My Feedback: (2)

That is CORRECT.

What Darryl is expalining is that the exhaust gasses are exiting the enigne nozzle at a 10 Dgree angle (+/-). For this reason the hot exhaust gases will impact the inside of the tail pipe for several inches in from the inlet.

We have an AP/ F-18c as well and that is exactly how we have it set-up.

Brg.

quentinmayberry

Anyone got a picture of the turbine exhaust tube setup that works, as I have the same issue with a Simjet 75N. Pictures speak volumes, just to ensure we are on the correct wave length here

Darryl Usher

Almost anything works! You need to test with an old fish scale to see what works best. You do not care what it reads, just higher is better.
Darryl