[aprssig] Could APRS work on a Mach 2 Rocket?
noskosteve at yahoo.com
Sat May 2 00:06:49 EDT 2009
This is a far cry from bouys and balloons, but ...
My son is an AeroSpace Engineer at a small, but advanced aviation related composite company in Colorado. One of the Techs there has a hobby of Extreme rocketry. These are very large 200 lb, 20,000 foot altitude rockets with the payload being three high speed (NASA style) 16mm cameras. Near as I can tell, They don't appear to have any telemetry and use Altimeters to blow recovery chutes and a Dog collar system for finding the (100 lbs of non-fuel) downed rocket parts (sorry couldn't resist). I can't tell for sure On the Design page), but the duration looks around a minute or four (18 seconds burn, rapid deceleration, free-fall, then 2,000 foot chute decent). Project link below.
They don't appear to have any hams on the project, yet.
These puppies reach 2200 fps (the noses are designed like high speed bullets) and can see accelerations of 14Gs (they pack their own rocket motors), "O" size ... Remember those Estes A and B things?... so the hardware survivablity is an issue, but...
I was thinking, how about APRS to provide *some* telemetry And get rid of the Dog collar.
Now, for sure, the Mach 2. can't be tracked by APRS (I have other ideas for that as well). Also, they do use aluminum bodies so antennas may also be an issue, but are going toward Carbon Fiber (what the company does and some pieces already are).
However, I had some thoughts. Some of you may be looking for a new challenge...
What would the 1200 baud do? This has to be primarily limited by the GPS used. Would it have some sort of Velocity "gimble-lock"?
What about the lower altitude accuracy of GPS?
What if they did 9600 baud APRS to their ground station, store it then re-transmitted it at 1200 baud into the APRS land system to get semi--real-time into the net?
I calculate the Doppler to be (2200 fps~1400MPH abt 1/10 LEO velocity) or 300HZ on 2Meters - 900 Hz. on 440. This could be doable at 9600, I think. Or else use a ground receiver capable of WFM like my TH-F6A. or a 706.
They aparently don't know about Twitter, so I tweaked them on that.
The Rocket Project:
cc: my son
-- 73, Steve, K9DCI
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