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July 20th, 2008
06:39 pm


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Rockets and Stuff
NARAM, the national model rocket contest is next week. I have been building models today. It is a great excuse to order cool stuff that I have no earthly use for. My latest whimsical expenditure was on a material called Kapton. On a per pound basis it is about the same price as silver. It comes in a 24" wide roll of .003" thick red sheet.

I have been using the stuff to make egglofters. Egglofters are models that launch eggs as high (or as long) as possible and still get the egg back unbroken. Eggs are heavy, weighing in at about 60 grams, so the weight of the model is at a premium. Eggs are not very streamlined, so a shroud to streamline the egg shape is also at a premium. Enter the Kapton. Egglofters tend to be shaped like an ice cream cone. The egg is encapsulated at the ice cream end with the parachute right below inside the cone. The cone is made of a sheet of Kapton curled to shape and held together with double sided tape. The pointy bottom end is cut off just enough to allow an engine tube about 3/4" in diameter to stick out. The fins are glued to the engine tube.

The Kapton is considerably lighter than the card stock that is often used for the cone. The difference in mass can make a 100 meter difference in altitude for a model launched with D impulse engines(20 Newton-Seconds).

Current Mood: accomplishedaccomplished

(2 comments | Leave a comment)

[User Picture]
Date:July 21st, 2008 01:55 am (UTC)

I don' b'lieve yu . .

Eggs are not very streamlined

Maybe not in regards to air, but in regards to liquid and oviduct tissue, they are extremely streamlined. They gotta be, in order for us to ever meet them in the first place. Hens have to transport them through such "condensed matter" once every 26 hours, and they keep that up for 3 to 4 years with only occasional breaks
[User Picture]
Date:July 21st, 2008 01:55 am (UTC)

Re: I don' b'lieve yu . .

Yes, I married a poultry science major
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