Just before I left the Air Force, the unit I was assigned to purchased Geodex systems for every officer. Geodex was similar to DayRunner or File-o-Fax and was basically a notebook full of the myriad details that you needed for life.

Alas, Geodex is no more. This truly sucks because it was one of those instances where the implementation lived up to the promise of the original concept.

Anyways, one officer I worked with didnÂ’t want his Geodex because he already had a system that worked for him, so he gave the whole thing to me to use. I loved it and used it for several years, finally giving it up when I could no longer get the annual refills needed to keep it current.

Since then, IÂ’ve relied on post-it notes, various lists jotted here and there and numerous notebooks and steno pads. Nothing very formal, nothing very organized, but good enough to get by with.

Obviously, I’m not one of those people who runs right out to get the latest and greatest technology. I still don’t have a cell phone, let alone a PDA. A PDA always fell under the category of ‘nice to have’ – if I ever had a few hundred dollars to spare. Being married with teenagers in the house, you can imagine how often that happens.

GPS was kind of interesting, but for me the main idea would be using it to triangulate the position of a rocket when it landed, hopefully cutting down the time spent searching for rockets that come down out of sight. The kids and I have always used the human method, where one stays back and marks a distant landmark, then uses hand signals to direct the searchers to the correct line to follow. It works better than guess-and-by-golly, but itÂ’s far from perfect.

GPS always fell into the ‘nice to have’ category too, but my sensible (and better) half is starting to convince me that it’s time to modernize all-around (hint: when convincing me, it helps to use a bigger 2x4).

I’m feeling the need for a PDA, and Garmin makes a model – the Garmin iQue 3600 – that combines the features of a good PDA with everything I need in a GPS system. The damn thing is almost $500.00, but Liz made the point that with the amount of money I’m risking per rocket launch nowadays (motor parts, electronics, chutes, etc), that if the GPS helps me locate a rocket or two that I might otherwise lose, then it’s practically paid for itself right there. Like I said, she’s the sensible member of the team.

Still with me? Cool. This is a long, meandering way to finally get around to asking if you have a PDA or GPS, and if so, what it is and how it works for you? What do you like about it? What do you hate about it? What would you change about it?

DonÂ’t have one? Why not? IÂ’m curious and collecting experiences and opinions here. Thanks.

Posted by: Ted at 11:33 AM | category: SciTech
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Here's a good explanation of what aerospike rocket motors are all about.

There are pictures here, and if you select the medium or large sizes, you can really study the detail of the aerospike design (if that sort of thing floats your boat).

The names and organizations involved are familiar to rocketeers, because this is the kind of cutting-edge experimentation that some of us get involved with. Here's the inside scoop from Chuck Rogers, one of the people involved, as posted on the Rec.Models.Rockets newsgroup (links added):

Cesaroni Technology Incorporated did a great job on the structural design and fabrication of the aerospike. The aerospike retrofits onto an O5100 motor in place of the conventional conical nozzle. BlackSky Research built the Optimal 168 rocket, and ran the launch operations for the flights.

The aerospike is a centered Prandtl-Meyer all-external expansion design. It delivered 97% of ideal efficiency in ground test (exceeding historical Rocketdyne data), and theoretically would deliver the same high efficiency from sea level to vacuum flight conditions.

The rocket flights were to demonstrate operation of the aerospike in flight, and to measure installation effects compared to the uninstalled ground static firings. CFD was run not only for the aerospike hot gas flowfield, but for the combined rocket and aerospike plume flowfield.

This is the most highly instrumented high power/experimental rocket ever flown. In addition to highly accurate accelerometers and pitch, yaw, and roll rate sensors, the rocket used a conic nosecone with a built-in Flush Air Data System (FADS) (like a pitot tube), calibrated with CFD and cone pressure tables. This was the first inflight direct aerodynamic measurement of angle of attack on a model, high power, or experimental/amateur rocket.

Blacksky Research coordinated the development of the aerospike nozzles and solid rocket motors, provided overall project management on the contractor side, and really helped refine the whole concept of using large high power rockets for advanced flight test research. All at a low cost relative to normal government aerospace projects.

Composites, ferrous and non-ferrous alloys, a little bit of graphite and a pinch of tungsten.

Well, it turns out that the tungsten tip on the aerospike is REALLY SHARP. While walking around the rocket as it was mounted on the transfer cart I got "speared" by it. It put a tear in my shirt, but it didn't break the skin. It did not draw blood!

For this experiment we wanted a "pure" spike that went all the way to a sharp tip. For an "operational" aerospike there is predicted to be very little performance loss for up to a 25% reduction in the spike length.

You'd want at least some minimal truncation to avoid that VERY sharp tip.

Which was suggested by CTI, but again, for the "purity" of the experiment we wanted a sharp tip.

Posted by: Ted at 05:22 AM | category: SciTech
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This redefines 'task-lighting', eh?

A U.S.-Israeli laser designed to protect northern Israel from missile attacks downed its largest rocket to date during a test over the southern New Mexico desert, the Army said Friday.

Posted by: Ted at 07:06 PM | category: SciTech
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Note: my link for this has expired. Here's an alternate that still works, but it references the same dead link I had. In the meantime, here a quote from the original source:

"Thus, if the Minuteman III ICBMs have to be used in some future nuclear war, their rocket motors will not pollute the atmosphere. EPA regulations do not apply in foreign countries, so no changes are being made to reduce the harmful environmental effects of the nuclear warheads"

That's right folks, Uncle Sam's ICBM arsenal is now more environmentally friendly because their propulsion has been reworked in order to meet EPA regulations.

Update: The 'dead' link works again.

Posted by: Ted at 05:07 AM | category: SciTech
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