AlphaKilo

Now I just need some free time.

Now I just need some free time.

The draft of the OpenMP 3.0 specification is avaiable for review. I’ll have to update my Intro to OpenMP presentation.

I have had success compiling a library that uses OpenMP with the gcc 4.2 compiler on my G5, and then linked that library with an Xcode project. In addition, the application is Cocoa based, so I now have OpenMP working with Cocoa and Xcode. The key was adding libgomp.1.0.0.dylib to the project along with ompcax.o. I would think I could have linked libgomp into a libompcax, but nothing i tried in that direction seemed to work.

Now the question is, can I get Xcode to use gcc 4.2, and is that version of 4.2 up to date with what ever magic Apple puts into their release of gcc.

I’ve had my new toy for just over a week now. The browser is very nice, I have not used a nicer browser on any phone, and it makes the Nokia3650 it replaces look very lacking indeed.

What I like

• The iPhone feels very nice, good weight and good balance
• The screen is sharp and clear even in full daylight
• The screen is sharp and clear even in full daylight
• The browser UI is slick, particularly the zoom on an div feature, sights that are not designed for mobile are still very accesable
• better coverage than T-Mobile, at least in Lincoln, MA

What I dislike

• Not only is EDGE slow, it seems to only be available 80% of the time I try to connect, and that is in Burlington,MA which AT&T claims is well covered
• My fat fingers are still clumsy on the keyboard
• A few UI discrepancies
• can not re-order weather or stocks lists
• can not add jpg received in email to the photo browser
• freezes: three times I’ve had to reset the phone

I picked up the 8Gig model Friday. Yes, I’m a fan. But it is both beautiful and has even been useful. A big step up from my Nokia3650.

Just a list of some of my favorite stores for R/C Airplane items
http://www.servocity.com

http://aeromicro.com/

My Nokia 3650 has a photo server setting. The default is OFOTO, but I added my own server so I can look at my http.log and see what is up. There would be an advantage to using the built in interface.

208.54.94.6 - - [17/Feb/2007:13:58:26 -0500] "POST /x HTTP/1.1" 404 199 "-" "Photo Upload (7650/1.0)"


Well it is actually a documented API -

What I thought would be a few hours work to get a WordPress J2ME photo upload working has turned into a longer effort. And at this point I think it is worth updating from Netbeans 3.6 to 5.5 and seeing if it all doesn’t just work on OS X. I don’t care for the small screen on my XP machine, and the 256Meg I have on that machine make it painful to use.

No Native Installer for the Mobility Pack, but…
There is a solution detailed here.

This discussion is moved to a permanent RC Airplanes page.

Christmas shopping reminded me how far the state of the art has advanced for model airplanes. For $30 you can get a 3 channel LiPo powered plane that is also so light weight it will survive most crashes. It’s not quite small enough to fly in my yard, but the park up the street is plenty of space.

I started again to do some design work on my own models; which will include video, and at least some form of navigation. I’d also like to maximize flying time, so here are a few back of the envelope calculations on what I think I can expect.

Power Required to Stay Aloft

A nice analysis is done at www.rc-soar.com. A quick look suggests I can get a 1.25 ft/sec sink rate for a on a 60″ model weighing in at 1.25 pounds. The aspect ratio is 8, giving a chord of 7.5″.

E = mgh (Energy = mass * force of gravity * height. )

In 1 second the plane drops 1.25 feet, and weighs 1.25 pounds. Gravity is of course 32 ft/sec^2. The energy loss in one second is (1.25 ft) * (1.25 pounds) * (32 (feet / (second^2))) = 2.1070055 joules. And of course a joule/second is a watt of power. So the power needed to maintain altitude of this model is in the ideal case 2.1 watts.

Think Solar

Sunlight provides best case about 1 kilo watt per square meter. The model above has a wing area of 60″*7.5″ = 0.3 m^2. This would provide 300 watts. So with just 1% efficiency solar conversion I should be able to stay aloft. I’ve seen solar cells advertised for sale to be 20% efficient, and a decent brushless motor should be 80% efficient. I have a factor of 16 in my favor.

Conclusion

Give the above, I am optimistic in thinking I can make a solar power R/C sailplane.

What About Night?

A sink rate of 1.25 ft/second over 10 hours is a loss of altitude of 13.71600 kilometers. Seems unlikely I should expect to stay up all night. Of course 2 Watts * 10 hours = 20 watt hours. I think the motor will run at about 10 volts. Watts = Amps * Volts, so I would be running at .2 amps, or 200mA. Now 2000mAh is not so unreasonable to expect from some batteries, so maybe I can get an all night flight in.

Reality
With solar cells, motor and batteries, the plane will not likely weigh 1.25 pounds. Power expenditure is linear with mass, so with my factor of 16, I might be able to build a 7 pound plane and still be ok - It will just fly faster.