NAVAL ACADEMY BALLOON MISSIONS

Bob Bruninga, WB4APR (bald, white shirt)

March 2012: We are building a high altitude Jet Stream sensing Balloon Payload for launch mid March 2012. It will be launched in Annapolis Maryland and hopefully give us sensor data from the Jet Stream out across the North Atlantic. This page will remain up-to-date.

Description: This balloon payload will only weigh about 50 grams. About the mass of two standard 9v batteries. It will use about 10 Mylar Party balloons to achieve constant-pressure flight level above 40,000 feet in the Jet Stream. The Telemetry will be in CW on 28.223 MHz and will contain Battery voltage, inside and outside temperatures, and surface luminosity of the ocean/clouds. It has no GPS. More... later.... as the students prepare the images and data (usually the last thing done!)...

CW Format: The CW format will be something like this. It is assumed that all outside termperatures will be below zero or negative so the minus sign is not transmitted. The inside temperature might get above 0 during sunlight. So assume the I inside temperature is positive and the outside temperature is negative in Degrees C. When the inside temperature goes negative then the I will change to IN to indicate negative temps. The outside Temp is always negative. If it goes positive, then the value will be replaced with an X.

. . . W3ADO I nn T nn APRS.ORG . . . <== inside temp positive and outside negative

. . . W3ADO IN nn T X APRS.ORG . . . <== inside temp negatve and outside positive

The CW message will be repeated once a minute or so. The WEB page may be sent only on every other beacon to save power. A photo resistor looking down will report the Luminosity of the ocean and clouds. During the day it will send a Daylight or D xx value and at night it will change to a Nighttime number N xx. The luminosity count is inversly proportional to light level. The larger the number, the darker.

. . . W3ADO I 10 T 40 D 07 APRS.ORG . . . <== inside 10C, outside -40C, Daytime Luminosity "07"

. . . W3ADO IN 20 T 43 N 75 APRS.ORG . . . <== inside -20, outside -43, Nighttime Luminosity "75"

TRACKING: The balloon has no GPS. All tracking will be done by HF DFing. The luminosity value will give us a time-of-sunset data point. All APRS users are assumed to know how to enter an APRS DF bearing report so that their DF bearing line shows up on global APRS maps. Those without APRS DFing capability, can email their reports to this address [ TBD ].

------------------THE REST OF THIS PAGE BELOW IS HISTORY OF OUR PREVIOUS LAUNCHES -------------------

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April 1991: The above photos are from our April 1991 launch. Notice our nice tracking antenna in the background.

June 2000: The photo above is our Sunday 26 March 2000 trial-balloon payload that was launched from the Baltimore Hamfest consisting of two 3v Lithium batteries, a 555 oscillator with thermister and a 10mW 433.92 MHz key chain transmitter inside a tiny plastic bottle. It weighed less than 16g and rose to over 20,000' on a single 18" party balloon (Which we underinflated and ended up using 3 before we got it up in the wind). It was a trial test of our launch and tracking capabilities in preps for our larger 1 April APRS balloon launch (whichi was canceled). The balloon was tracked and chased across the DLMARVA penninsula and out over the Atlantic when we ran out of land on the shoreline near Dover Deleware. The balloon had only a temperature sensor, but when matched to an elevation temperature profile we got this telemetry:

  • 1230 launch
  • 1306 temp was 65 at about 2500 feet
  • 1400 temp was 54 at about 8000 feet
  • 1430 temp was 48 at about 11,000 '
  • 1500 temp was 34 at about 18,000 '

    See USNA Radio Club's PHOTOS and description of the Launch and chase.

    We are contemplating another launch on a weekend in April to let some other Midshipman clubs participate in the chase and recovery. Sort of simulating a "downed flier" search and resue mission.

    APRS BALLOONS: Balloons make a good test bed for small satellite payloads that are very low cost. Mission duration may last from a few hours to a few days and just about matches the modern student's attention span. The Naval Academy has launched one such payload in 1993 which was detected as far away as South Carolina and Conneticut.

    APRS SETTINGS: One of the most critical aspects of Balloon Mission design is the use of proper APRS settings. This has always been problematic. A 2-hop path is desired once the balloon is on the ground and lost, but was a nightmare for early balloon launches before the New-N paradigm. Now that most of the APRS network is New-N compliant, balloons may safely get the advantages of 2 hops using the same generic WIDE2-2 recommendation of all other mobiles. These 2-hop paths do not cause dupes throughout the network, becuse the New-N paradigm system eliminates all dupes assuring that each digipeater throughout the huge footprint of the balloon will only transmit the packet once and only once.

    Further, since the APRS New-N network has all digis with UIDWAIT set to 0, this means that all digis will digipeat the packet at the same time using up only one time slot, no matter how many digis are involved.

    DO NOT USE WIDE1-1! Notice that WIDE1-1 should NEVER be used on a balloon or any other high altitude aircraft or anything that can hit large areas. This is because most of the WIDE1-1 digipeaters only do callsign substitution and are not part of the WIDEn-N algorithm. When these packets get delayed for whatever reason by a second or so, then other digi's hear them and can end up with multiple dupes from every nearby digipeater.

    PACKET RATES: These balloons will be seen by everyone within hundreds of miles, and although they do not add more than the equivalent of a local mobile traveler, they should adhere to the same gentlemenly rules of channel sharing as everyone else. In that regard, short duration flights should never use a packe period any shorter than once a minute. FOr longer duration flights, a 2 minute rate should be considered.

    Select any ofthe following replays of missions:

    Return to the main APRS page