EOSS-350 COSGC Fall Launch - Recap

The launch on November 11, 2023 from Deer Trail, Colorado was flight EOSS-350, one 3000g balloon, launch time was 6:57am. There were 24 payloads from COSGC, it was a site to see the balloon go up followed by 24 payloads covered in shiny silver tape reflecting the sun. The payload burst at 79,405 ft.  Twenty two cars filled with students went to the landing site at County Rd 8 and MM, south east of Cope, Colorado.  It was a short wait till we had land owners approval to walk the half mile out to the payloads.  I counted as 59 students and EOSS personel hiked out to retrieve the payloads.  A good day for all of us.

 EOSS-350 final calculations

Original Announcement: 

 EOSS 350 Heavy and EOSS 350Lite and 35Lite updated to show student weights and revised 351L EOSS bottom payload.EOSS 350 Rev B updated to show new flight number and shorten flight string to under 100ft. Balloon count for this launch is currently  either one 3000g balloon or two 1500g balloon carrying 24 student payloads currently weighing 8kg from Colorado Space Grant Consortium schools.  The students will need the full 4kg on the light balloons.If cloud cover exceeds 5/10ths then two lite ballons will be flown as follows

Live flight tracking during the flight: https://track.eoss.orgFllight prediction: https://eoss.org/predict Mileage for EOSS 350 https://forms.gle/qJjy47iTHF5ywDPJ6 

Event Date: 
Saturday, November 11, 2023 - 00:00 to 23:45
Flight Coordinator: 
Launch Site: 
Punkin Center X=30, Y=20, Test: N39.00 W 103.00 = X=67.5 Y=30.3


COSGC Fall Flight, one 3000g balloon or two 1500g balloons containing student payloads.

Balloon Type: 
Rocket Man 12 ft Release Adam
144.905KC0D-2remote release-DFfrom flight plan top:10 :40
Payload Plan: 

EOSS Preflight Net @ 7 PM Mountain Time preceding night:
        •  449.225 MHz (-5 MHz Offset, 141.3 Hz CTCSS) Rocky Mountain Ham Radio (RMHAM) Repeater and EchoLink *CANONCTY* conference and the Fun Machine linked system
        • 146.940 MHz (-600 KHz Offset, 103.5 Hz CTCSS) Rocky Mountain Radio League (RMRL) Repeater if the RMHAM machine is down
        • 146.640 MHz (-600 KHz Offset, 100.0 Hz CTCSS) Denver Radio League (DRL) Repeater will serve as a backup to the backup repeater 

Launch Site:
        • 446.050 MHz Simplex  
        (Note that some radios assume these are repeater frequencies and attempt to put a 5 MHz offset in the transmit frequency automatically)

Track & Recovery Operations:
        • Primary FM Repeater - 449.450 MHz (-5 MHz Offset, 103.5 Hz Tone) 

        Simplex Frequencies:
        • 446.100 MHz Balloon #1 Field Simplex 
        • 446.150 MHz Balloon #2 Field Simplex
        • 446.200 MHz Balloon #3 Field Simplex
        • 446.275 MHz Car to Car drive out Simplex
        (Note that some radios assume these are repeater frequencies and attempt to put a 5 MHz offset in the transmit frequency automatically)

Skyhub links to primary FM repeater (449.450 MHz):

  • Limon (Cedar Point) - 447.650(-) MHz, 103.5 Hz
  • Hugo - 447.150(-) MHz, 103.5 Hz
  • Firstview - 447.600(-) MHz, 103.5 Hz


Digital Mobile Radio (DMR):

The decision as to which talkgroup use will be made by the EOSS RF Coordinator on a per flight basis.

  • Rocky Mountain Wide Network – Talk Group 700 - Rocky Mountain Ham Radio has approval to the use "Wide" for flight operations.
  • Central Colorado Regional Network – Talk Group 720 - On occasion, EOSS may use the Central Colorado Regional Network (Talk Group 720).

2M Direction Finding Frequencies:

  • 144.340
  • 144.360
  • 144.905
  • 145.535
  • 145.645
  • 145.710
  • 145.765


Tactical Calls: 
TacticalCall SignNameNotes
BravoW9CN, NØJPSMike, John
CharlieNØRPF, KØBRARob, Doug
HotelKCØRPS, WØGVJim, Gerry
YankeeKEØYALNot Available
Ground StationN2XGL, N5JK, KB0TVJ, N0ALLJeff,Tom,Russ, Randy
TR Breakfast: 
6:00 at IHOP in Limon (Optional). Prediction: Cope, CO NS CR-XX, EW US-36, X=74.5 Y=78.5