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2-24-2014 ~ Blog # 595 (David)
I made another rocket from scratch; I'm pretty sure it's the best rocket ever. I started with a 3.8 inch diameter plastic Easter egg and a 29mm F sized motor mount tube. The free form fins are 1/4 inch balsa. At only 98 grams I thought an F sized motor might be a bit much so I built it on a simulator and found that with an F42 it will accelerate at 39 gees to Mach 0.44. I'm pretty sure this rocket would shred well before Mach .44 so I made a F to D motor adapter. An Estes D12 motor should top it out just under 160 mph; I think it can handle that speed. The recovery system is tumble. With a spent motor the center of gravity of this rocket is just in front of the center of pressure. When the motor ejects it will slide back (with the adapter) 2.25 inches; at this point the center of gravity and center of pressure are pretty much in the same place. At this point the rocket should become unstable and tumble. With the big fins and light weight its decent speed should be limited. I need to do some "wind tunnel" tests to confirm the stability and instability with the motor in both positions.
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2-23-2014 ~ Blog # 594 (David)
Check out the GFS Maskenball page.
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2-17-2014 ~ Blog # 593 (David)
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2-14-2014 ~ Blog # 592 (David)
Today was a fail:
Hopefully the driver of this truck learned that if there is a No Trucks sign on a road, it really does mean: no trucks. He scraped his way under the old railroad/new bikeway bridge on South River Road today.
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Sledding with the Georgia Wilsterman's 2-8-2013 ~ Blog # 592 (David)
John, Jean, Kira, Luke and Marian are visiting us for the weekend. We had a great afternoon sledding at Munroe Falls Park. Videos to come. We put up to eight people on a big inner tube and five on the supersled. The supersled is so fast that it crosses the paved road that's 50' beyond where all other sleds come to a stop. Here's an MP4 video of three runs. I've recently discovered that although MP4 files will play directly in all media players, they play without sound when played in a browser. How is it possible that browsers do not fully support one of the most common media formats?
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2-8-2014 ~ Blog # 591 (David)
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