I stand by my spreadsheet from last week. It predicts:

Event    Elapsed time (s)  Height (Agl, ft)
Drop        0                       2600
Drogue     8.3                    1500
Main        17.5                   750

However my simulator that I'm writing says:

Event    Elapsed time (s)  Height (Agl, ft)
Drop        0                       2600
Drogue     8.9                    1500
Main        22.7                   750

The reason my simulator thinks the drogue stays open longer is given
the Cd and area of the drogue it thinks the decent speed is slower.
The spread sheet uses Tim's decent speed he gave me. I think I would
trust the spread sheet more that the simulator at this point.  Besides
probably better opening early rather than late.


On Wed, Apr 15, 2009 at 12:05 AM, Andrew Greenberg <and...@psas.pdx.edu> wrote:
> Hi!
>
> Since using Keith and Bdale's shiny new flight computer wasn't really an
> option, and I wasn't terribly keen on laying out a board for the LPC
> header board... Keith talked us into option "C".
>
> 1) We're going to use the current "smashed up" LPC2148 board to log the
> SCP1000 output to flash. Dave is going to use the current firmware, and
> simply start logging until the flash is filled after we press both
> buttons on the dev board.
>
> 2) I have a GPS unit that fits in a small plastic box. We can use that
> to log data, too :)
>
> 3) Instead of building up a whole other temporary flight computer, we're
> going to use two timers. In particular, I'm trying to get two of these:
>
> http://www.perfectflite.com/catalog/microT2.html
>
> The idea here is that the static line now starts the count down of these
> two timers, one for the drogue and one for the main. Dead simple.
>
> Tim and Nathan: can you please come up with independent timer values for
> the following scenarios:
>
> 1) Drop at 2,600 AGL
> 2) Deploy drogue at 1,500 ft AGL.
> 3) Deploy main at 750 ft AGL.
>
> Thanks!
>
> Andrew
>
> --
> -------------------------------------------------------
> Andrew Greenberg
>
> Portland State Aerospace Society (http://psas.pdx.edu/)
> and...@psas.pdx.edu  P: 503.788.1343  C: 503.708.7711
> -------------------------------------------------------
>
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>

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