Minimum tail pipe diameter
 

For a small turbine (10-15lbs thrust) what is the smallest size of the tail cone diameter without causing problems with the turbine and airflow? Pipe length is 20-24 inches and the pipe opening at the turbine can be anysize.

Also, how hot will the tail pipe get (in degrees), and what are your suggestions for maximizing temperature protection to the airframe?

Thanks

ScaleME