My Thoughts Exactly

A beautiful little short film from the NYC Bicycle Film Festival.

Helmet Forensics

Since Oscar was riding solo, we've been trying to piece his ride together. Today we were looking at his helmet. He can't remember if he was wearing it or not, but my wife said he walked into the apartment with it in his hand, so He had it with him.

Last summer I brought him down two helmets; a Bell Venture (what I wear) and a Bell BMX/downhill full-face. He prefers the full-face style wise, and that is what he had with him.

This is all speculation, but looking at the forensic evidence, it looks like he was wearing the helmet, and I am glad it was the full-face.

1.) Looks like the point of impact was right on the face-guard. He probably would have broken/lost some teeth (happened to me once) if he hit face first with a regular helmet. The helmet saved his face.

2.) There are also chips on the top left of the helmet, so it looks like momentum carried him over in a somersault and he hit the top of his head too.

3.) There are some scratches barely visible inside the helmet. The polystyrene did not break, therefore did not dissipate the the impact's energy. The semi-hard shell, took the brunt of the punishment.

4.) Looking at these impact marks, looks like his brain was sloshing around in his skull pretty good. Probably the first impact, the brain's frontal lobe hit the front of the skull, the second impact probably just sloshed things around a bit more.

I will replace this helmet when I return from the USA in July. He also wants some body armor. He got a few scratches on his right leg and right arm.

My Wind Tunnel (updated)

Science Fair is on Friday. My students are frantically finishing up their projects. Most of my science plans have been put on hold until next week.

I have a 7th grade student who is really interested in airplanes and flight. This gives me an opportunity to dust off my classroom wind tunnel and let this particular student gather some data on various wing designs for his science fair project.

I built my first classroom wind tunnel in 2003, the 100th anniversary of the Wright brother's flight at Kitty Hawk. A travel version model of the first generation wind tunnel was presented at the 2005 NSTA national convention in Dallas, TX. It was there I met Bill Nye, the Science Guy, and I was able to give him a private presentation of some of my projects. He liked what he saw. He liked the idea and the design. He encouraged me to build a second generation.

This wind tunnel was built around late 2005 or 2006 by me and one of my high school students. This second generation wind tunnel has a couple neat features like the external lever system and separate test chamber. The main body and test chamber is made from sheets of polystyrene, but unlike the first tunnel, the suspension system, as mentioned above, is external and made from balsa wood. The models inside are attached to the suspension via PVC plastic drinking straws.

It works pretty good but of course there is always room for improvement. Right now it only measures lift, and I still want to build a system to measure the drag force on the model. I've made prototype models of a drag system that I think will work pretty well, but just need to get around making it from balsa.

Some day I'll get around to making a 3rd generation.

Carnival! [Day 2]

Check the Horizon

Went sailing today on Daniel's boat.

Not much wind going out so we had to use the outboard. Once we were far enough out, we caught some wind and tried to tack to Isla Borracha. The boat began taking on a serious amount of water. We headed back to Los Borrachitos so we could figure out what was wrong.

Once in a tiny cove, dug around and found a small hand bilge pump. We would have to fill our beer cooler with water then dump it overboard. Each stroke of the this little pump would spit out about 500 ml (1 pint) of water. It would take at least 100 strokes to fill the beer cooler. This soon got tiring and we decided to rig up a small electric pump we found. It was not powerful enough to send a column of water up and over the rail, but it was easier to fill the beer cooler than the hand pump and soon we had to boat empty of water.

A cotter pin came loose from one of the stays on the main mast and we could not put it back in due to length of the cable. We decided to go out, put up the main sail hoping sail would tweek the mast so we could put the pin back in place. Daniel had go out on the rail do the fix but it worked.

Then water started coming back in...a lot of water! I went below and hooked up our makeshift electric bilge and started the bucket brigade once again but we were not making any headway. Water was coming in faster than the pump could take out. I asked Daniel if all the seacocks were closed. He thought so...

Borracho y la Borracha

A couple more beer coolers full of water and Daniel asked where the sink drained. I looked under the sink and found our problem. The drain pipe had come lose and the seacock was open. Water was coming in like a firehose! The seacock was frozen, but with the help of a Leatherman tool, Daniel got it loose and closed it. Then we were able to empty the boat of water via our electric bilge pump/bucket brigade method. We probably emtied at least 1100 L (300 gallons) of water.

Came home and watched Ben Hur on TMC with Tania. I hadn't seen that movie since I was a kid. It is really good. Last night we watched Bridge on the River Kwai, also very good.