ORIGINAL: tIANci
Dan - you are really speaking Greek! Hehehehe ... anyways, its enlightening. So the loss can be as muchas 30% ... would th intake lip help if the fan unit is inside the fuse but it does not use any intake ducting? What I mean is that it sits snug but then the housing is still a square lip, might rounding it up help even if its a snug fit? I hope you get what I mean.
LOL!
If I understand you correctly, you're asking about mounting the fan inside the fuse without ducting, but with the sides of the fan shroud touching the sides of the fuselage.
Yes, having an inlet lip on the intake will help, but only until the air gets past it. After that, it'll do two things unless there is some sort of ducting:
1) Immediately become turbulent.
2) Slow down due to expansion.
For an example, make a tube (cylinder) and a cone out of paper. Blow air through the tube. It should exit as fast as it entered. Now, blow air through the small end of the cone. What happened to the air as it exited the big end of the cone?
Now, because the fan is mounted fairly close to the fuse walls, it will suck in the air and blow it out the tailpipe, but not with as much thrust or velocity as it could with a well-designed inlet lip and duct.
I'm building an F-106. With the fan mounted in a test stand using a MF480 inlet lip, it pushes the air out the tailpipe at 160mph. Mounted inside the airplane, it's pushing the air out the tailpipe at 150mph, for a loss of only 7%. If I had a loss of 30%, it would only exit the tailpipe at 112mph. Big difference.