Originally Posted By: Astro14
Originally Posted By: chiefsfan1
Originally Posted By: Astro14
Actually, even more impressive than the stealth is the "mice" in the intake.
Let me explain: the annular area in the intake, aft of the spike, was critical to Mach 3 flight. The spike had to be positioned with an accuracy of 0.1" for the inlet to function properly, decelerating and compressing the air for the J-58.
They calculated the annular area with a slide rule. But once the tooling was built, and the inlet assembled, changing the size would have required redesign and retooling. So, in case flight test demonstrated that they needed to adjust the area, they built it a hair bigger than calculated, then they added small bumps, the size of mice, were bolted into the throat to slightly reduce its size. They could increase the throat size (annular area) by removing mice to fine tune the inlet.
But the slide rule calculations on pressure and supersonic flow were perfect.
The original mice stayed in place for the entire service life of the airplane. There was no need to ever adjust the inlet size.
Have you seen this?
http://www.enginehistory.org/Convention/2013/HowInletsWork8-19-13.pdf
That is a great link! No, I've not seen it before, but I've downloaded it onto my iPad to read later. I just remember the anecdote from Ben Rich's book, "Skunkworks", which I read years ago...and I understand a bit on how the inlet works from other sources. The F-14's inlet was designed for lower speed (2.3 IMN) but also for high alpha performance, so many of the principles are the same, but the execution is far different...
Thanks!
You are welcome!! page 10 has a cool pic of the SR71 I have not seen before. Its the one plane I have never seen fly either. Although on its last retirement flight from LA to DC I calculated the flight time on when it would hit KC. It was cloudy that day but I heard the BOOOM. That night on the news there was a report on it and said from KC to St. Louis was IIRC 7 minutes.