Saturday, February 20, 2010

Inlet data for ramjet strap-on pod

This post is really for my on-line buddies at It is one of multiples to come that I hope they can use. For an old ramjet engineer like myself, this has been a most cathartic experience.

These images are from an inlet estimate that I did recently, for the concept design of a ramjet strap-on pod for space launch. I used the old 1953 publication NACA 1135 as the source (something most of us old compressible flow people acquired rather early in our careers).

The design is for a translating-spike, all external compression, axisymmetric nose inlet. Specifically, it is for angle-of-attack 0 degrees, but for axisymmetric nose inlets, performance is essentially invariant out to about +/- 15 degrees off-angle.

Definitions are:

The basic inlet recovery and spike position data are:

Inlet-related drag data are:
It was a lot of fun doing this. I haven't done this kind of thing for over 15 years. Nice to know I still can. This was all by-hand, pencil-and-paper work. I put it into an Excel spreadsheet for graphing. The graphics program I used for pictorials, and for data transfer to this site, was Microsoft's Windows accessory "Paint".

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