Archive for September, 2009

Open source tools for CFD


Karoliina’s pineapple smoothie (recipe)

You need the followings:
– 1 liter: Tropicana Pineapple juice.
– 1 package of coconut milk
– 3 bananas

Mix together until the mix is smooth (with power mixer).

Aerodynamic efficiency index, AEI

I have been trying to come up with my own formula (that differs from the various CAFE formulas to have a weighting that suits me better). I found another interesting comparative formula, the AEI.

AEI = (W0*U0)/hp

where W0 is the gross weight in lbs
where U0 is the free stream velocity in ft/s
where the hp is the horse power required

In other words for Diamond DA40 this is:

W0=1200 kg = 2640 lbs
U0= 214 ft/s (127 kts cruise at 10000 ft)


AEI(Diamond DA40) = (2640*214)/90
AEI(Diamond DA40) = 6277

Unlike the CAFE formula this has no weighting for these parameters.
If I would like to make my formula based on this, I might want to weight the hp a bit more.
That is because the lower the hp figure gets, the better is the fuel economy if everything else remains constant.

Why this index is good? Because it isolates aerodynamics from structural engineering and does not care how much useful load the craft has. It only considers the aerodynamically important point, how much power is required to move the mass forwards and at the same time keep it on air.

Minimizing fuselage drag (external link)

Bruce Carmichael: Minimizing fuselage drag.

AOPA article about Klaus Savier’s 100 mpg Vari-Ez

Here is a link to the article by AOPA about Klaus Savier’s Vari-Ez.

“For all these guys that think magnetos are so great, I only have one question: Why don’t you put magnetos in your cars?” Read more by clicking the link below:

Jet glider conceptual study (link)

Hands on with the new amazing Nokia N900

There has bee a lots of interest around this new device and the Maemo 5 operating system. Lots of positive comments and then I have read some comments where people doubt that the transitions would be just some flash animations and not a real thing (which of course is not true). Well, this is a OpenGL hardware accelerated Maemo device, and all you see is real. Quim Gil just posted on Twitter a link to a new video showing how the Maemo UI works, if you had doubts, you can put the doubt aside and see by yourself. The user experience is slick and beautiful.

You can find the video from here:

In my opinion, the UI experience on the Maemo 5 has improved greatly over what it used to be and also over the competition. It is really pleasant to use and there are not so many things that would be annoying. There certainly is lots of wow, and this kind of shows the innovation these days is occuring in the mobile space rather than on desktop, desktop environments are already lagging behind and the transitions on these UIs are not so practical they are in Maemo where they are all well thought and well implemented and not just random eye candy and special FX without purpose. Maemo 5 really rocks on this segment.

There is also an article about hands on experience on N900. Slashgear is reporting from Nokia World conference. There is both video and lots of good pictures included. This shows how the device looks like rather than the UI. The video I mentioned above is better showing how the UI functions.

And here is yet another hands on video. This is also very good:

And here is the replacement for a gaming console.

The Nokia N900 can be used as accelerometer equipped controller and connected to a TV. Hint for game developers: Here is the great platform to start developing games. The platform supports full OpenGL ES 2.0 and a OpenGL-ES game does not even need to care that much what Maemo version it will run on, Maemo 5, Maemo 6, and the GL is standard. It is not a bad long term investment to invest on Maemo. The N900 has a capable graphics accelerator (for this small mobile device) as can be seen from the Bounce game and from also the UI which heavily relies on the accelerated 3D graphics. The capacity of the device is great – it has plenty of RAM and there is plenty of flash too on the user’s home directory. And if the RAM would not be enough, there is also virtual memory like on any modern operating system nowadays. The games don’t need to be that simple and amateurish anymore “mobile games”, I am quite confident that anything that has been done for Wii could be done for this device, in other words, this could be used as a serious gaming device despite that is not what it was primarily targeted for (as it is Internet device really). But like computers, there are many uses for the single device. Also, the device can be always connected, so massive multiplayer games would be superb on this. Looking forward to try some serious 3rd party games in the future! Hey Austin, if you read this, please port the X-plane, I want it.