Tuesday, June 29, 2010

Taking a break

I've parked the Fokker at the Airport while we are in Phoenix for a week.

I have a few details yet to finish when I get back. This will be a good chance to evaluate where I am with this stuff. There is a little irony in the fact that I have spent $600 on a computer to run a free program.

Monday, June 28, 2010

Visiting Mexico

One of the photo sites I continue to visit regularly is the Flickr Kite Aerial Photography (KAP) group.

This great photo of a Tijuana bull fight by "El Kite Pics" was made with a kite-suspended camera from the U.S. side of the border. Be sure to read the story about making (and taking) the shot.

Saturday, June 26, 2010


I decided my airplane needed some identifying insignia, so I set about figuring out how to do that.

The tail surfaces are flat and present no difficulty, but the fuselage and wing surfaces have curves that resist direct drawing techniques.

The maltese cross image was projected onto the slightly curved sides with a technique demonstrated in a video tutorial by Aidan Chopra, author of "SketchUp for Dummies".

For the crosses on the wings, I tried a plug-in tool that allows drawing on curved surfaces, but I couldn't achieve the kind of precision needed to complete the design successfully. In the end, I used the same technique that allowed me to cut the hole for the cockpit.

A form with the desired profile is pushed through the surfaces, the two objects are merged, and new edges and surfaces are created. Once an area is enclosed with a continuous perimeter, materials and images can be projected or painted onto it without leaking onto the contiguous surfaces.

I've also scaled back the cowling a bit to give the plane a profile a bit more in line with photos I've seen of it. I'm planning on tweaking a few more details, laying on some color, and hope to wrap up this project in a week or so.

Stuck in traffic?

Take the next left and unfold your wings.

Tuesday, June 22, 2010

All the parts together

I'd like to do a bit more with this Fokker d.VIII, but my old Dell computer is balking at the prospect. In order to display the shadows in this image I had to turn off hardware acceleration, so the process really slows to a painful crawl. I have learned quite a bit from doing this model, however, so I think I can put this one in the success column too. I can go back to doing simpler models for a while as there is still a lot of the basics I need to learn.

Monday, June 21, 2010

Back to the Future

Ray gun optional.

Visit the Martin Aircraft Company Limited web site for details on development, and to put in an order. There are some nice videos, pictures of demo flights and jetpack lore, as well as a good 3D animation.


One of the aspects of 3D modelling that I enjoy is the research which allows accuracy, or at least reasonable resemblance, to the object being depicted. While looking for some guidance on how to draw a propeller, I came across this fine blueprint at the excellent Wooden Propeller site. There is also a wonderful illustrated article on the art and craft of propeller construction.

The next challenge is how to translate a good plan into a SketchUp drawing

Saturday, June 19, 2010

one dollar flight

I bought five of these Chinese-made kites at the dollar store.

I was attracted to the design, which is similar to the Indian fighter kite or the Nagasaki Hata. The kite is made from very light-weight materials, including small-diameter plastic spars.

Everything needed came in the package, including the winder, the kite string, a plastic ribbon tail, and a nice little clip for attaching the line easily to the kite bridle. This type of kite needs no bow string; the pressure of the wind on the surface forms the airfoil.

A lot of cheap kites look good, but are poorly made and unflyable. This one was designed and produced by people who understand kites and how they must be made to fly properly. A well-balanced fighter kite is very maneuverable. Letting out a bit of string allows the kite surface to flatten, and the kite begins to oscillate back and forth. When the nose is pointed in the desired direction, a strong pull on the line bows the horizontal spar, forms the kite surface into a lifting shape, and the kite moves briskly in the direction it is pointing.

I also picked up the Mini Copter and the four-inch Spiderman kite, which flew better than I expected.

One of the neat things about kites is that they demonstrate the capacity of humans for intuitively deducing very complex laws of physics. Kites were invented thousands of years ago, probably in China. While the disciplines of mathematics and physics were little developed then, the kite makers nevertheless were able to solve some extremely complex design problems, and to achieve a working understanding of the principles of flight. Because of the flexibility of kites which responds to variable wind pressure, their flight resembles that of birds more than it does modern fixed-wing aircraft.

To get an idea of the variables and the formal calculations required for the design of a kite, take a look at the on line Kite Modeler program posted on the web site of the National Aeronautics and Space Administration.

Some useful thoughts about inductive reasoning can be found in a posting at Slashdot.

around and around

I'm working on a new SketchUp model of a WWI plane. The 110 hp engine in it was an Oberursel Ur.II, a German product copied from a French design. I was vaguely aware that in such rotary engines, much of the machinery went around along with the prop. It wasn't until I began looking at CAD representations that I began to understand why the rotary was considered a good idea at the time, or what made them work. Two CAD depictions in particular make the functioning of rotary engines a lot easier to understand.

The cut-away depiction below is from the marvelous Vintage Aviator site. If you look closely you will see the key feature of the engine, which is that there are two axes of rotation.

How the machinery is linked by the two axes is illustrated with great simplicity by an illustration at the Animated Engines site. Once there, click on the "Gnome Rotary" link to view the animation. Under the "About" link, you will also find an excellent explanation of how the engine animations are produced.

Saturday, June 12, 2010

Friday, June 11, 2010


The first 35mm film was conceived of as a motion picture format in the labs of Thomas Edison. The format was put to use in a large number of miniature still cameras in the first decades of the Twentieth Century, including the Leica. The pre-loaded 35mm cassette was the invention of Dr. Ernest Nagel of Stuttgart who devised it for his Retina line of compact folding cameras. Kodak acquired the Nagel factory in 1931 and began marketing the Retina cameras and the film, which was designated as Kodak 135, in 1934.

The interactive 3D model is at the Warehouse.

Thursday, June 10, 2010

Tuesday, June 8, 2010

Busman's Holiday

I spent the afternoon today modeling these 120 roll film spools which came along with my two oldest box cameras. The cores of the spools are turned wood, and the end caps are stamped sheet metal.

I needed a break from working on my latest airplane. Some little alignment errors have proven difficult to correct, and I'm not sure if this one will ever fly. I did learn several new SketchUp techniques in the process, however, so I still feel the time was well spent.

Monday, June 7, 2010

3D Art

Came across a link to this 3D animation this morning at the Filmwasters site.
Pretty extraordinary work.

If you look at the Youtube page, there are a number of similar videos listed in the righthand column, many done by UC Berkeley students. I've been wondering how 3D design is being approached in schools, so was pleased to find these examples. According to the Filmwasters post, the Brownie Hawkeye Flash was done in Solidworks.

Thursday, June 3, 2010

Thirty seconds over Alejandro

Our grandson's visit provided an opportunity to fly this Walmart micro helicopter, an Air Hogs Sharpshooter model.

I wasn't sure, judging from my own initial experience that the little chopper was a good choice for an impatient eleven-year-old. With just a little practice, however, he was able to fly the craft and control it much better than I. I was reminded of my own kids who, even when much younger, were out-performing me at Pac-Man in less than an hour.

The Sharpshooter proved to be a pretty stable flyer, though offering limited navigational control. It has taken a lot of hard knocks, but still gets airborne.

The charging port seems to have a short which turns on the motor unexpectedly, but that hasn't been a problem once you anticipate the thing trying to take off while you are in the process of connecting the cable. As I thought, the missle-firing capability proved to be an attractive feature. However, the craft flys poorly with the little plastic rockets in place. Small issues aside, however, it seems like a pretty nice toy at thirty bucks.