EOSS-238/239/240 STEM Flight - Recap

More graphs and data, and a few in-flight pictures posted.

National Space Science & Technical Institute (NSSTI) has posted a YouTube flight video captured during the flight of EOSS-240. An updated "Director's Cut" video is posted here.

If anyone has pictures of the flight, please send to the Flight Coordinator at KC0RPS@arrl.org. Thank you


It was a beautiful day for a balloon flight.

  • EOSS-238 launched at 0830, ascended at 887 ft/min (avg), reached 96,575 ft., and landed at 1059.
  • EOSS-239 launched at 0844, ascended at 983 ft/min (avg), and reached 98,297 ft.
  • EOSS-240 launched at 0856, ascended at 1,057 ft/min (avg), and reached 98,471 ft.
Original Announcement: 

Final Payload Plans have been posted.The 24-hour predictions is posted below. This is the best estimate of the flight path. Here is the flight prediction for use with TrackPoint.Here is a link to a series of websites that contain weather and flight predictions, and real-time tracking during the flights.This will be exempt balloon(s) supporting STEM programs in Colorado. Currently we have the following programs onboard:

 These flights are scheduled to launch at 0830 (and every 15 minutes thereafter) on Saturday March 18, 2017. The balloons are scheduled to launch from Deer Trail, Colorado. Click on the blue link for maps and directions. As we get closer to the launch wind predictions may change and the launch site may have to change as well. Watch this website for updates. The current prediction is shown on the figure below (green is going up, red is coming down).Here is the 24-hour prediction for the flight path. This is the one to print out and take with you. The GFS surface conditions forecast for 0900 MT Saturday shows cool temperatures (47 F) and near-calm surface winds.  Maximum cloud coverage predicted at 3/10.  Mean regional snow cover is 2 inches.  Temperature at 0600 MT forecast to be 36 F. The NWS point forecast for Limon (nearest location) shows a temperature of 49 F and 4 kt winds at 0900 MT.  Average cloud cover from 0/10 to 2/10.  Click on the Payload Plans below to see the details of each balloon.

Event Date: 
Saturday, March 18, 2017 - 00:00
Flight Coordinator: 
Launch Site: 
Last Chance, 40.40 Test N39.74068, W103.59356, Ans: 40,40


An exempt balloon for Colorado Springs School

Balloon Type: 
1500g Totex latex balloon
5.8 ft orange and white nylon parachute with spreader ring
144.340 MHzKCØD-14APRS/Digi/DF EOSSTimeslotted at 0:00 and 0:30 seconds
147.555 MHzAEØSSCW/cutdownDF Beacon
144.360 MHzAEØSS-9APRS BeaconSecondary Beacon


This is an exempt balloon that will fly payloads for:

  • Chatfield High School Junior Engineering Class
  • Montclair School of Academics and Enrichment, 4th and 5th grade scientists

Montclair will fly a GoPro Camera to record the view from the balloon throughout the entire flight.

Balloon Type: 
1500g Totex latex balloon
9 foot Rocketman High Altitude Balloon Payload Recovery Parachute
144.340 MHzAEØSS-8APRS BeaconTimeslotted at 0:10 and 0:40 seconds
144.950 MHzKEØBMV-11APRS/DF BeaconSecondary Beacon


An exempt balloon for the National Defense Industrial Association, coordinated by National Space Science & Technology Institute.

Two Payloads weighing a total of 5 pounds maximum. These payloads will contain physics and engineering experiemtns from High School students, 4th, 7th, and 8th graders.


Balloon Type: 
1500g Totex latex balloon
8.5 ft circumference Sphereachute with cutter and fast release
145.750 MHzKCØD-12APRS/DF/CutterSecondary Beacon
144.340 MHzKCØUUO-11APRS/DigipeaterTimeslotted at 0:20 and 0:50

Preflight Net:

  • 147.225 MHz CRA Repeater (107.2 Hz Tone) 8 pm MDT preceding night
  • 146.940 MHz (103.5 HZ Tone) RMRL Repeater if the CRA machine is down
  • 146.640 MHz (100 Hz Tone) DRL will serve as a backup frequency

Recovery Operations:

  • 448.450 MHz PPFMA (100.0 Tone)  New Primary
  • 449.450 MHz RMRL (103.5 Hz Tone) Backup
  • 446.100 MHz Field Simplex (Balloon #1)
  • 446.150 MHz Field Simplex (Balloon #2)
  • 446.200 MHz Field Simplex (Balloon #3)
  • 146.550 MHz Backup field simplex
  • 446.275 MHz Car drive-out frequency

Launch Site Simplex: 446.050 MHz

HF - Possible ops: 7.235 LSB

Tactical Calls: 
TacticalCall SignNameNotes
AlphaWAØGEH, KCØDMarty, MarkEOSS #238, Tracking Coordinators
BravoKBØYRZ, NØNDMChris, LarryEOSS #240, Tracker, Alternate Alpha
CharlieKDØSEM, KE0CQQDave, RyanEOSS #239, Trackers
DeltaKØSCC, NØIXStephen, DougEOSS #239, 240, Launch, Trackers
EchoKE7KCKTomEOSS #238, 239, Launch, Tracker
FoxtrotKCØRPS, WØNFWJim, GeorgeEOSS #240, Flight Coordinator, Tracker
TR Breakfast: 
Watch for fire hazards in the fields!!! It is dry out there. Glory be! Launch time is 8:30!!!. Trackers will meet for breakfast at Denny's in Limon, CO at 6:45. We will depart at 8:00 to explore the recovery area which (ironically) is the same area as #224. Communications will be rough. We will start by using 449.450 and 446.100 and then move to the assigned freqs. Due to the short list of trackers, trackers have been assigned specific flight responsibilities. Please note your flight assignments and prepare your TrackPoint accordingly. Be on the lookout for a good staging point for the students to rally. To minimize APRS traffic on .34 in the endgame, let's keep our transmissions down to every 4 minutes which might help with endgame issues. The new TrackPoint will offer the opportunity to timeslot those transmissions so they do not interfere with the balloon transmissions. Very cool. See you on the net at 8:00 Friday night. - Marty