Future L3's - Northern Colorado Rocketry

This topic has 49 replies, 15 voices, and was last updated 15 years, 10 months ago by mule.

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October 26, 2009 at 11:02 pm #51320
Adrian
Participant
I just took a quick look at today’s balloon sounding data for Denver and Grand Junction, and the 5 points I looked throughout the air column at had between 0 and 1.4% difference.

Temperature, dew point, and wind direction vary more from station to station than pressure vs. altitude. More comparisons are needed, though, in order to get a better feel for typical errors introduced by this method.

Update: Reno and Elko have about 1% difference also.
Reno and Oakland have about 0.5% to 1% difference.

Next I’ll take a look at Reno and Medford Oregon just before the front went through at BALLS this year. That should be kind of a worst case for before/after the storm front.

That one was mostly 1% different and all points less than 1.5% different. So far, so good.
October 27, 2009 at 12:35 am #51321
Kenneth Reilly
Participant
OK, i get that the balloons are sampling pressure at various altitueds. How is the altitude of the balloon when the pressure is sampled determined?
October 27, 2009 at 12:38 am #51322
Adrian
Participant
OK, i get that the balloons are sampling pressure at various altitueds. How is the altitude of the balloon when the pressure is sampled determined?

GPS or radio location. The other NCR Ken works for the company that makes those now, and IIRC the pressure sensor spec accuracy was about 0.1%
October 27, 2009 at 1:34 am #51323
John A. Wilke
Participant
OK, i get that the balloons are sampling pressure at various altitueds. How is the altitude of the balloon when the pressure is sampled determined?

GPS or radio location. The other NCR Ken works for the company that makes those now, and IIRC the pressure sensor spec accuracy was about 0.1%

Which brings us back to where we started. If we use GPS to discern balloon altitude which is, in turn, used to discern pressure (which may be from a balloon that is 100 miles away) and is assuredly higher (or mayber lower?) than our rocket, aren’t we predicating everything on GPS to begin with?

Here is where the rubber meets the road for me. The GPS lock of a dog collar or other GPS transmitter is almost assuredly not happening at apogee. So… it would appear to me that whatever the GPS says is a best-case scenario. There is no judgment, there is no stray weather pattern causing barometric aberation, there is no front moving through that may cause a variance in our readings…. “it is what it is”, to coin an overworked saying.

On my GPS, elevation is the last thing that is determined – lat and lon are first. Is it thattaway with all GPS units? I don’t know, hence my question.
October 27, 2009 at 2:41 am #51324
Ed Dawson
I’ll start a new thread as we are way off topic. We are also spending more time flying altimeter against altimeter instead of rocket against rocket.
October 27, 2009 at 2:55 am #51325
edward
Moderator
I agree with Ed, we are pitting altimeters against each other instead of rockets. If I try for the K site record next year, which is very tempting, I’m probably going to ask to see if I can use the altimeter that the record was set with – to me that levels the playing field way more than balloons do.

Edward
October 28, 2009 at 2:53 am #51326
mule
Participant
Good lord, you guys hijacked this one big time. It’s all lost under this title…..
November 9, 2009 at 2:13 pm #51327
Dr_J
Thank you all for your participation in this special. This turned out to be a very popular special.

Same for Pro98. If the M2505 is too large for your rocket, you can go with the 2G version and a spacer. That motor is not yet certified, but is scheduled for later this month. It will be ~M1630. The 4G version will be available as well later this month. ~M3400 as demo’ed at Ofest.

Both these motors are available now. See the announcement at Rocketryplanet. Our web site will be updated shortly with the thrust curves and all data.

Jeroen
November 9, 2009 at 5:04 pm #51328
mule
Participant
Thank you for offering it!!! Very much appreciated Jeroen!!!
November 12, 2009 at 5:46 pm #51329
mule
Participant
I spoke to Ken @ GLR today and he said he will be taking care of everything with this deal. If anyone is concerned, don’t be! All is well and going through as supposed to be. We may need to contact him directly with payment info, but not at this time. Tim hasn’t handed product and data over to Joe yet, so please just give these guys a week or so to get things organized. If you do have a concern, please contact them.

Greg
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