Plotting and Printing Airfoils in Matlab

Gah, got tired of monkeying around with various software (XFLR5 is never provided as an executable on ANY platform despite countless requests, just some packets) so loaded up a profile in Matlab and plotted it in multiple sizes and printed those. Took only a few minutes. It’s still the best software ever.

It went something like this:

load MH78.txt %text file is copy-pasted from MH-aerotools.de
whos %check out if it worked
MH78 %check out what we just loaded

figure
plot(MH78(:,1)/100,MH78(:,2)/100)
grid
axis equal
legend MH78

%perhaps print here if it fits on one paper

%this is three views for a larger print:
xlim([0 0.4])
%print here manually
xlim([0.3 0.7])
%print
xlim([0.6 1])
%print

%Etc you get the idea...

Had to read some documentations for this, but the gist is that Matlab actually has some proper documentation. I just typed help gca, help set, help axis, help axes, help xlim etc and they contained some quick examples that I then tried and got the hang of everything. Matlab should be the gold standard for all similar software developers. I’ve tried coding in Python and Scilab and both have large stumbling blocks in quick and efficient numeric work.

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Industrial Climate Software

I just updated the blog title and again just watched the page and the blurb.

It’s when we start working together that the real healing takes place, … It’s when we start spilling our sweat, and not our blood.

It’s a quote of David Hume, my favorite philosopher. I haven’t read his books though. I was reading a Finnish translation of one but it seemed so tedious with the language that I couldn’t bother. So me favouring him is based on the works of others about him.

The quote reminded me of the conflicts that I’m witnessing. The subject line matter needs to be done. At the moment many parts of climate software seem to be science software – written by people in a hurry with little planning, and code that has seen different people adding bits and pieces here and there, making it a big mess. Fortran and supercomputers and all that. Well, most software is a mess. Twenty man years, said MT. That’s a small amount of money considering how much is at stake and even compared to the amount of huffing and puffing efforts around the subject. I am available.

What else needs healing and sweat spilling? Well, quite many things. Including stuff in my personal life.

There are lots of old (sometimes Fortran) code packages hanging around. Nuclear stuff, rocket trajectory calculations, rocket engine chemical/thermodynamics performance… You name it, anything a young man is interested in seems to depend on these archaic pieces of software. So there’s a lot of potential work here but it seems so big for just a lone person to do much on their own free time.

The blog title picture is just some hinge flapped NACA foils simulated with the vortex lattice method in QFLR5. That actually IS a free software project, mostly by Andre Deperrois and uses Mark Drela’s XFOIL for 2D calcs. In the picture, the front wing has NACA 4415 with 6 m span, 1 m chord, 25% chord 15 degree full span flap, and the tail is a NACA 0012 with 2 m span 0.5 m chord, 40% flap or elevator at -15 degrees. Flying at 5 degrees AoA (plus 4 deg to the front wing) and 18.9 m/s, lifting about 2000 N. Absolutely no guarantees about the results.

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Clear Climate Code

A project you can partake here. Rewriting some NASA GISS temperature record code in Python at first.

I’d go further and say things like these should not be volunteer efforts… government codes for something important like this should be open (and GISS is) with people being paid to update and keep them in good shape. Hopefully they can take things like these as templates.

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climate.google.com

Michael Tobis, a climate scientist, thinks climate modeling is progressing too slowly and might have even reached a plateau of sorts. There still aren’t very good regional precipitation predictions for example.

And he thinks, far simplified, that the disorganized mess of patching the old fortran codes is the reason – the climatology community should take a new example from the commercial sector which succesfully develops complex distributed software. Like Google.

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