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ZL3AI > APRDIG 02.07.03 09:26l 125 Lines 5233 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Jun 29, 2/2
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Data from KPC-3+/failure analysis of balloon payload
From: "Rochte, Robert" <rrochte@gpacademy.org>
Date: Sun, 29 Jun 2003 23:32:13 -0400
X-Message-Number: 7
Background:
The "Spirit of Piccard" solar Montgolfier had a successful flight one week
ago of almost exactly eight hours duration with a maximum altitude of nearly
50,000 ft (about 10k feet above predictions). The altitude figure is the
result of much post-flight analysis, combining pilot reports with the
intra-envelope temperature logger data, upper-winds data and the flight
track. The recovered envelope shows signs of gradual softening and melting
at altitude -- this likely due to reduced convective cooling in the low
stratosphere. The envelope essentially functioned as a very large parachute
for the last 2.5 hours of the flight. The flight began in Sterling Heights,
Michigan and ended just outside of Bellefontaine, Ohio.
My questions:
The last APRS packet to enter the network and show up on Findu was sent only
two hours into the flight, just south of the metropolitan Detroit area at an
altitude of 26k feet. After this, nothing was received. My first suspicion
was a dead battery, but it turns out that the payload was definitely
transmitting when it was retrieved later that evening (the pulse rate of the
piezo buzzer mounted on the outside of the payload varied significantly when
the transmitter was keyed and this behaviour was reported by the man who
found it). In fact, the radio (an HTX-202 at 1 watt output) and TNC were
both powered up when I recovered the payload five days later! The GPS had
failed after less than 24 hours (the last message in the KPC-3+ track buffer
was from 1:22am the following night), apparently due to a weak cell in the
battery pack (it simply tapped off one cell), but it was apparently running
the duration of the flight.
All of this is *not* what I expected to find (i.e., everything working!) and
has caused me a great deal of confusion. I'm really left with one thought
-- that the antenna (a 1/4 wave HT whip from MFJ, poking out the bottom of
the payload with a 1/4 wire counterpoise attached to ground and run up
inside of the payload box) was simply too pathetic to be received at
altitude and/or outside of a major metropolitan area.
Is this a reasonable explanation? I had originally considered using a wire
J-pole or a ground plane, but really thought that the 1/4 wave whip would be
sufficient once I was up in the air. Was I way off in this assumption??
Also, I am just now looking at the "stations heard" (using the "j" command
in PBBS mode on the KPC-3+) and, oddly enough, I see three stations
(including one from south of Columbus) with a date stamp of June 21 (the day
*before* the flight) and several more from the day *before* I retrieved the
payload. I'm assuming that the date is off by one day -- but it should have
been set by the GPS. Is there another explanation for this? And is there a
reason that I would see so few stations in here (i.e., is there a limit to
how many stations are logged)?
Thanks for any help in interpreting all of this.... The multi-disciplinary
aspects of this project have been quite a bit more intensive than I had ever
imagined!
Regards,
Robert
KC8UCH
--
Robert Rochte
Director of Information Technology
The Grosse Pointe Academy
171 Lake Shore Road
Grosse Pointe Farms, MI 48236
Tel. +1 313-886-1221 x155
FAX +1 313-886-1418
www.gpacademy.org
----------------------------------------------------------------------
Subject: Re: Data from KPC-3+/failure analysis of balloon payload
From: Bob Bruninga <bruninga@usna.edu>
Date: Sun, 29 Jun 2003 23:46:08 -0400 (EDT)
X-Message-Number: 8
On Sun, 29 Jun 2003, Rochte, Robert wrote:
>has caused me a great deal of confusion. I'm really left with one thought
>-- that the antenna (a 1/4 wave HT whip from MFJ, poking out the bottom of
>the payload with a 1/4 wire counterpoise attached to ground and run up
>inside of the payload box) was simply too pathetic to be received at
>altitude and/or outside of a major metropolitan area.
Naw, you could hear that for 100 miles. On my one and only balloon
flight we noticed a drastic signal drop after balloon pop, but heard it to
the ground. On recovery, found that the antenna wire had broken off and only
about 1 inch of wire was acutally radiating.
>Is this a reasonable explanation? I had originally considered using a
>wire J-pole or a ground plane, but really thought that the 1/4 wave whip
>would be sufficient once I was up in the air. Was I way off in this
>assumption??
So I dont think so. Look elsewhere. Good l uck.
Bob
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Subject: Raw Mic-E conversions?
From: "Dick Stanich" <dick@kb7zva.com>
Date: Sun, 29 Jun 2003 23:1:12
X-Message-Number: 9
Does anyone know what version WinAPRS stopped converting raw Mic-E packets
and injecting them back into the APRS-IS, if you ran an IGate?
Still seems to be a problem with Mic-E mobiles showing up where they
haven't been. Like Africa, the Atlantic Ocean, the Pacific, or the next
state.
Dick, KB7ZVA
APRSwest.net
http://kb7zva.com
---
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