Hovercraft | Homemade

Would you like to ride on a nearly friction-free vehicle? You can make one with some plywood, plastic sheeting, duct tape, blower, and basic tools. Most of the students in my high school physics classes were seniors. Because their graduation was about a week prior to the end of the school year, I still had several juniors in each class for several more days. They were asked to do a project of their choosing and demonstrate it on their last day. In 2002, a student built a working hovercraft similar to this one. I got to be a test dummy for her project. It was great fun.

Recently, we vacationed in Yellowstone Park. On our return trip, we visited that former student whose family has remained good friends with us. She was going through some boxes of old photos and discovered three she knew I would enjoy seeing. She was correct.

Basic instructions

  • Plywood sheet 4 ft wide with a hole large enough to accept blower hose. Tape it in tight.
  • Heavy-duty plastic sheet taped securely around the rim and under the plywood.
  • Cut 8-10 one inch diameter holes in the plastic sheet spaced uniformly.
  • Sit in the center, turn on the blower, and glide away.


Miss Pickerell and Me

One of the first books I remember reading was Miss Pickerell Goes to Mars written by Ellen MacGregor and illustrated by Paul Galdone. It was published in 1951. It had a strong influence on me. Many other young readers apparently felt the same way as evidenced by the comments on this page at Goodreads. That book made me hungry for more adventures in science by the independent spinster with a pet cow who was willing to say what was on her mind.

I read about her trips to the Arctic and the Undersea as well as her adventure with a Geiger Counter. The science in each book was explained in ways a young person could understand. I have no doubt those books helped reinforce my interest in science. I became a teacher of physics for my career. Thank you, Miss Lavinia Pickerell and Ellen MacGregor.

MacGregor first wrote for publication in 1946. A class assignment for the Midwest Writers Conference was later published as a book Tommy and the Telephone. Miss Lavinia Pickerell first appeared in a story by MacGregor called Swept Her Into Space published by Liberty Magazine in 1950. That story was expanded to book length in 1951 and published as Miss Pickerell Goes to Mars.

She wanted to offer literature to children with an emphasis on science. Much of the science was not considered known or tested and was classified as science fiction. The explanations in the books used the best known science of the day to tell the stories. Her works were well received by critics. Her first Miss Pickerell book about Mars was the initial selection of the new Weekly Reader Children’s Book Club. I still have a pin I got for reading a certain number of book club selections in grade school.

Three more Miss Pickerell adventures followed before MacGregor’s early death. Copies of the four books are available in different formats from Fadedpage. This link to the Ellen MacGregor collection describes each and provides formats in txt, html, kindle, epub, pdf, and zip files for download.

MacGregor kept many notes on more books she intended to write about Miss Pickerell. Twelve additional books were written from those notes by author Dora Pantell between 1965 and 1986. More contemporary topics were in these later Miss Pickerell adventures such as harvesting the sea, weather satellites, earthquake rescue, supertankers, energy crisis, blue whales, and the war on computers. I have not read these books by Pantell. But, I am confident they are good.

Mt. St. Helens | Eruption | 18 May 1980

The eruption of Mt. St. Helens in Washington State 37 years ago was a spectacular event. Upwelling of magma caused the mountain to be forced slowly and strongly from below. On the morning of 18 May, a huge landslide occurred on the north slope face of the mountain. Rock, timber, snow and ice, slid down the face. The event allowed the volcano to release pressure and begin its eruption.

Ash was projected high in the sky and was caught in the high altitude westerly winds. The dense cloud of ash drifted east blocking out the midday sun across the state. Ash settled down on communities causing confusion and havoc.

In the path of the settling ash was Manastash Ridge astronomical observatory run by the Dept. of Astronomy of the Univ. of Washington. Douglas Geisler was working at the observatory throughout the night of the 17th into the early morning hours of the 18th. He said the skies were excellent for telescope observations. He went to bed at about 5 am.

A loud ‘boom’ barely interrupted his sleep. He went back to sleep until about noon. When he got up to go outside, it was dark.

“Yikes! – There is no day. It’s completely black; thick, inky black with visibility ~10 feet (with a flashlight), & it stinks. This is the end of the world.”

In the logbook for the 19th, he noted for the record the sky condition was black & smelly. He also noted he lost 6 hours of observing due to volcano (good excuse, huh?)

He thought he might be the last survivor of the war as he remembered hearing a ‘boom’. He turned on the radio and heard ‘cha cha’ music. Why was the world playing music at the end of the world? Eventually the radio station from Yakima said that Mt. St. Helens ‘blew its wad.’ He was relieved.

It remained dark until mid-afternoon. Several inches of ash settled on the ground. Visibility improved to about 1/2 mile by dusk. He covered the telescope and instruments to prevent damage. He took some pictures of the dome and surroundings thinking he might make a lot of money on his story. But, he never followed through.

SpaceX | How They Do Booster Landings

SpaceX, the private rocket launching company owned by Elon Musk, has had successes lately with commercial satellite launches. On 1 May 2017, they launched the military satellite NROL-76 from historic Launch Complex 39A at the Kennedy Space Center in Florida. Another major accomplishment by SpaceX is the successful landings and re-use of the stage 1 booster of the Falcon 9 rocket. This has never been done before, not even by NASA. The way I see it, that story deserves some explanation.

Watch this compilation of clips from the most recent booster landing, their 4th. The landing takes place on an unused pad not far from launch complex 39A a short distance up the coast. I wondered what flight path the stage 1 booster took to allow it to return back to this spot near the launch site. Most of its fuel had been used to get it and the stage 2 payload to high altitude, far downrange, and going very fast. The flight needed to be very efficient.

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Saturn | Cassini Mission | Grand Finale

Launched 15 October 1997, the Cassini Mission is in its 20th year. It reached Saturn and entered orbit on 1 July 2004. Details of the mission can be read at this Wikipedia summary. This post is mostly about the maneuvers by Cassini to change its orbit and make 22 close encounters with Saturn in what is called the Grand Finale. End of mission is scheduled for 15 Sep 2017 when the spacecraft plunges into the atmosphere of Saturn ending a long and brilliant exploration of the famous ringed planet, its rings, and 62 moons.

Clean Room Workers Ready Spacecraft | NASA | 1996

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Vatican Observatory Tour

I follow the blog The Catholic Astronomer from the Vatican Observatory Foundation. I’ve heard of the Vatican Observatory for a long time but never knew much about it. It sits a above an extinct volcanic lake at Castel Gandolfo in the Papal Gardens near Rome.

© Paul A. Zalonski

Very recently, the observatory director and foundation director led a tour of the place. Joining them was Christopher Graney who is an astronomy teacher in Louisville, KY. He recorded videos for his class to see later. His videos are posted here on the blog site.

Scroll to the bottom of his post and click the left of three small images about the history and telescopes. His link will take you to the three videos.

One aspect of interest in the tour was of the women computers who worked there and their machine used to measure stars on the glass plates. It connected well with the work of the women computers in The Glass Universe by Dava Sobel. Those women laid the foundations for many of the important principles used in modern astronomy.