EOSS-300 GPSL - Recap

A single 1500g balloon was launched on Saturday, July 11, 2020 from the Atlas Missile Silo site near Crow Valley (Briggsdale, Colorado) to flight qualify EOSS beacons and release units . This flight was in concert with the Great Plains Superlaunch virutal group launch.

The EOSS flight was not a roaring success....  The ground wind at the launch site was 19 gusting to 25 mph, causing great difficulty filling the balloon. Dispite the efforts of a multiple-person team, the first balloon contacted the ground and burst during fill. A second balloon was filled and launched at 0802. The fill was not sufficient to achieve liftoff and the flight string hung up on a fence to the southwest of the launch site. The balloon was retrieved and additional lift gas was added. Prior to the second launch, a pea-sized hole was noticed in the balloon. The balloon was launched at 0819 and ascended slowly (~350 fpm) to an altitude of 11,224 ft MSL before starting to descend. The balloon touched down to the southeast, 4.3 miles @132° from the launch site. In the high ground wind, the payload string was dragged 179 ft.

After obtaining land-owner permission, a team hiked 0.4 mile into the field to retrieve the payload string. It was evident that the payload string had dragged some distance to the southeast.

A recording of the YouTube live stream is available at https://www.youtube.com/watch?v=5NLx54dHRjk

. A fairly choppy broadcast of the launch is shown from about 55:15 - 1:07:00
Original Announcement: 

7/8/2020 12:00pm The Launch Site has been changed to Crow Valley (click on the blue link for directions). This is a new launch site, 2.5 miles west of the campground on Highway 14, then 0.5 miles north to an abandoned missle silo (see map below).

Flight predictions are available at https://www.eoss.org/predict/ (updated at noon daily) and a detailed  list of data and tracking links are available at http://wxqa.com/eoss300.html


EOSS-300!! will be launched in coordination with the (virtual) Great Plains Superlaunch event.

The goal is for balloon groups to launch at the same time from their own sites.  It'd be fantastic to see as many balloons as possible in the air at the same time.  The launch time will be 1400Z (10am ET/7am PT) on July 11th to allow for maximum participation across the US and Canada yet still have plenty of the day for recovery.  Also, a mix of floaters and conventional balloons in encouraged. 

EOSS will be gathering (to the extent allowable under Colorado pandemic safety rules) to hold a celebration for EOSS-300. A barbecue is planned.




Event Date: 
Saturday, July 11, 2020 (All day)
Flight Coordinator: 


Edge of Space's 300th flight!! This is an equipment qualification flight that will be launched in conjunction with other GPSL participants as a virtual group launch.

Balloon Type: 
Totex 1500g Latex
12 foot Rocketman
144.340 MHzAEØSS-13APRS/Digi EOSSAPrimary
145.765 MHzKCØD-1Remote Release / DFSecondary, paired with release Adam
144.905 MHzKCØD-3Qualificationpaired with tethered release Charlie
145.645 MHzKCØD-2Qualificationpaired with tethered release Baker
1090 MHzN461SGADS-BICAO Code: A59EE9
Payload Plan: 

EOSS Preflight Net @ 8 PM MDT preceding night:
        • 449.225 MHz (-5 MHz Offset, 141.3 Hz Tone )  RMHAM Repeater  
        • 146.940 MHz (-600 KHz Offset, 103.5 Hz Tone) RMRL Repeater if the RMHAM machine is down
        • 146.640 MHz (-600 KHz Offset, 100.0 Hz Tone) 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:
        • 449.450 MHz (-5 MHz Offset, 103.5 Hz Tone) RMRL repeater .
        Simplex Frequencies:
        • 446.100 MHz EOSS-300 Field Simplex 
        • 446.150 MHz Optional Field Simplex
        • 446.200 MHz Hanger talk-in
        • 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)

We will be using RMHAM DMR "Rocky Mountain Wide"

        Legacy 2M Simplex Frequency (not generally used due to desense/interference issues with the 2M APRS packets)
        • 146.550 MHz Simplex

2M Direction Finding Frequencies:

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


Tactical Calls: 
TacticalCall SignNameNotes
AlphaWA0GEH. KC0DMarty. MarkAlpha Team
BravoW9CN, N0JPSMike, John
CharlieKC0RPSJim Flight Controller
DeltaK0SCC, KE0BMV,KE0BMUStephen, Parker, WhitneyDelta Strike Team
EchoKE7KCKTomEOSS President
GolfK0JWB, N0NKKJohn, NancyWelcome Back
Ground StationN2XGL, KD0NQU, KE0YUEJeff, Lisa, Tim, Randy
IndiaKA0ZFI, KB0UBZAnn, Ben
TangoKC0LJohn, Eileen