The NACA airfoils are airplane wing shapes developed by the National Advisory Committee for Aeronautics (NACA). These shapes are described by a series of digits, which are translated into actual shapes by a series of computer programs. These programs date back several decades, and were written in Fortran.
BRL-CAD's interest in this code is as a possible means of procedurally generating wing geometry in BRL-CAD models, but we would prefer to have the shape generating logic in one of BRL-CAD's standard languages - C or C++. The target code for this effort is a modernization of older NACA codes by Ralph Carmichael called naca456.
The initial conversion will attempt to precisely reproduce the functionality as currently expressed in the Fortran code - any more elaborate reworking of the logic will be evaluated after we have a C/C++ version that reproduces the Fortran outputs correctly.
This task depends on the successful completion of tasks #1 - #4 - this file makes use of the files from those tasks. Students shouldn't claim (and mentors shouldn't assign) this task until the others are complete.
Your task involves the following steps:
- Download and build the original naca456 from http://www.pdas.com/naca456download.html
- Verify that the samples at http://www.pdas.com/naca456samples.html work correctly with the original naca456
- Check out the git repository: git clone https://github.com/starseeker/naca
- Build the C++ naca456 (cd naca; mkdir build; cd build; cmake ..; make)
- Repeat the tests performed with the original naca456 using the new C++ version.
- Compare the outputs and make note of any differences.
- Correct the C++ code to make the new outputs, if any differences are observed.
- Submit any necessary patches, either to the task or via a github pull request if you prefer to work in a git fork.
- http://www.pdas.com/naca456.html
- https://github.com/starseeker/naca
| File name/URL | File size | Date submitted | |
|---|---|---|---|
| task-36-verify-fix-naca-airfoils.diff | 50.2 KB | December 21 2014 00:58 UTC |
I would like to work on this task.
This task has been assigned to Andromeda Galaxy. You have 100 hours to complete this task, good luck!
This diff file includes the changes from the previous two tasks (convert #4 and #3.5), because it makes several modifications to those files, and I'm diffing from master; I didn't want to commit those files because I thought it likely that they would still need some work.
This patch should make the first 3 test cases on the linked site work; the output differs only in a small amount of whitespace and in that some of the numbers have small differences from the originals, which I believe are due to rounding error from the fact that C sometimes requires several operations to achieve what Fortran does in one, sometimes with a difference in ordering between them. I decided to submit this one with only the first 3 working because getting this far has already required 6hrs, and the previous two tasks both took ~5hrs each.
The work on this task is ready to be reviewed.
Congratulations, this task has been completed successfully.