Business, Space, Technology and Society

Is There An Aerodynamicist In The House?

23 Comments

I need someone familiar with both CFD and Method of Characteristics for a NIAC proposal due at the end of the month. This is aviation related, though it could potentially apply to space as well.

[Update on June 14th]

Still looking for one, now with some level of desperation, given that the proposal is due in two weeks.

[Bumped]

23 thoughts on “Is There An Aerodynamicist In The House?”

  1. Have no expertise in whatever you described.

    It made be remember a friend of mine.

    He’s a PhD mathematician.

    He once said he wished he knew more math so that he could be a particle physicist.

    His was an 80’s degree, before the mostly education implosion.

  2. Why use method of characteristics? I recall using it to solve compressible flow problems with shocks a long time ago. Modern CFD codes solve the same compressible flow problems.

    I think I remember there being a good description of it is Andersons book. Compressible flow with a historical perspective.

    1. Because there is a huge trade space to investigate, and it would be much more computationally efficient to use MOC than CFD. It will also tell a lot more about the far field (i.e., what is the overpressure on the ground). CFD would only be used to fine tune candidates.

      1. I assume you’ve done a lot of back of the envelope calculations, or has Office Depot’s many store closures made that a non-starter?

  3. huge trade space… OK that makes sense. Unfortunately it’s been so long I’d have to go back and look at Andersons book or one of my numerical methods books.

  4. I hang out here for the people way smarter than me.

    I’m not dumb. Just a beer or two short of a six-pack.

  5. I would guess there could be public domain codes from the old COSMIC distributions that have MoC solvers in them, and/or old NASA or AFRL reports with source code included (search DTIC).

    Another possibility is the Matlab File Exchange hosted by the Mathworks, but you’d need a licensed copy of Matlab (unlikely anything from there would run unmodified in Octave or SciPy).

    1. And when you say “CFD”, that covers a lot of ground. In descending accuracy: Reynolds-averaged Navier-Stokes? Euler codes? Panel methods? Vortex-lattice? Unless you need decent drag predictions, for free stream Mach number greater than maybe 1.5, an Euler code will probably get you more than sufficient accuracy, and don’t discount what you can get from a good ‘ol vortex-lattice method. (maybe something like this: https://airloads.net/Downloads/Panel%20Methods/A%20Generalized%20Vortex%20Lattice%20Method%20for%20Subsonic%20&%20Supersonic%20Flow%20Applications.pdf)

      1. Can I substitute a pair flash sticks for the sequential tape drives VORLAX wants to use on I/O channels 5 and 6?

        FORTRAN 4 ahhh those were the days eh?
        It appears one is free to use VORLAX after Oct 1977?

        I suppose it’s pure coincidence that some of those wire frame models look a lot like the B1 bomber?

        1. I didn’t look at the source, but a common Fortran extension was to call the different I/O channels “tapeN”, and you could map those to physical media at the OS level. At least it was that way on the CDC Cyber 175 that I used for a couple of years in industry. (Of course, NOS/BE was barely an OS; quite an adjustment after using Berkeley Unix during college – what do you mean, no file system???)

          1. And of course we think it’s better today, but abominations such as “git” tend to indicate otherwise :-/

          2. Berkley Unix got you spoiled. Since the comments to VORLAX indicate it was developed and optimized a bit on a few different System 360s, depending on how Lockheed had set up their IT shop, there likely would have been some special JCL cards put through the card reader at the start of the batch to control the mapping of the I/O. Tape would have been quite the luxury. Sure beats feeding in huge data decks.

            I hear you on NOS. At my school the Cyber was front ended with something more reasonable as I recall. Undergrads were allowed nowhere near it.
            Well not quite true. I did some 6600 assembly. Loved it. A, B and X regs. You could write whatever you wanted to B0 as long as you were happy to get Zero back. heh heh.

      2. It is an interesting problem.

        An euler code will run fairly quickly, for example the old Euler3D case with a million elements runs in 5 minutes or so, circa 2019, but capturing a shock overpressure many thousands of feet (meters) away might be tricky because the grid needs to be refined at distances not normally considered in an analysis. Dissipation of the shock might be an issue.

        A Phoronix testcase:

        https://web.archive.org/web/20190222083808/http://www.caselab.okstate.edu/research/euler3dbenchmark.html

        And is it one geometry at multiple mach numbers, or multiple geometries at multiple mach, or even worse, optimization with both in play? Things get gnarly quickly, most codes are written to run alone, sadly even in 2023 the scripting “glue” languages are still not first class, from what I can tell.

        But I am retired, so…

  7. Have you looked on LinkedIn?

    (I’m a AE, but my expertise is flight dynamics and control, and my employer wouldn’t let me anyway. But lots of engineers on LinkedIn. )

    1. Rand, This sounds like awfully short notice. I’m assuming you need primary number crunching by an expert. I’d make that clear in your LinkedIn search. Agree with cthulu.

      2. I don’t need anything immediately from the aerodynamicist except consent to be included in the proposal. I’m just trying to make the proposal credible in terms of the team.

  8. I’m old, and my medications make me say stupid stuff.

    I’m announcing my campaign for President.

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