Recap of EOSS-73

LAUNCH DATE: December 6, 2003
LAUNCH TIME: 08:14 am local (15:14 UTC)
LAUNCH SITE: Windsor, CO (directions)

Blue = Ascent
Red = Descent

EOSS Frequencies:

This is a preliminary frequency roundup. Payloads may be dropped and others added. Check back the week of the launch to be sure you have the most up to date information.

  • Preflight Net:
    • 147.225 MHz 8 pm MDT preceding Friday night
      • 145.160 MHz simulcast in the Springs
    • 146.640 MHz will serve as a backup frequency
  • Beacon
    • 147.555 MHz CW and Tracking tone
  • APRS
    • 144.340 MHz
    • ID: W5VSI-11
  • Tracking and Recovery Operations
    • 449.450 MHz 103.5 Hz tone (primary EOSS T&R Repeater) Rocky Mountain Radio League
    • 146.550 MHz simplex (same simplex for field and launch ops)
  • HF Net during Flight
    • 7228 KHz (see notes about this freq)
    •  starting at 14:30 UTC (7:30am MST)

Flight Systems:

Balloon Manufacturer Kaymont
Balloon Type latex
Balloon Size 3000 gram
Payload 25.8 Lbs.
Free Lift % calculated at fill
Ascent Rate 1010 fpm to 35K then diminishes
Descent Rate  966 fpm at landing
Parachute 10 ft. diameter
Peak Altitude 40626.97 feet
Launch Conditions determined at launch

See NOTES below regarding payload train configuration

Payload Configuration:

EOSS Grid:

Location X coord Y Coord
Intersection Highway 14 & 71 70 45
Ft. Lupton 10 9.5
Nine Mile Corner 75 13
Launch Point 2 35.5
Predicted Touchdown 65.5 31.4


HF Radio

We try and start an HF net approximately 30 to 45 minutes prior to launch on 7.228 MHz. If that frequency is busy we try 7.235 or 7.240 MHz.

Sparky, KA�DPC and Bruce, NA�BR will be net control

Expected Coverage

Map made with Radio Mobile Deluxe



  • Charts showing Altitude vs. Time and Ascent Rage


Tracker's Recap

by Benjie Campbell, W�CBH

Larry Noble (N0NDM) and I (W0CBH) left Aurora about 5:30 am and headed out County Road 73 to Roggin where we turned onto I-76 and proceeded to Fort Morgan. We met up with several other trackers at the McDonalds and had breakfast. We all then split up and headed to our assigned areas.

Larry and I went North about 10 miles or so, and then east of highway 52 about 5 miles on a dirt road that gave us access east and west and north and south in case the balloon went long from it's predicted touch down point. The computer was working very well, and Nick's program, Gridcalc-V! was doing its thing. We were able to track several of the trackers and the balloon.

When Marty, the tracking coordinator, told us the balloon was not ascending higher than 40,000 feet, we realized that it was not going to make the predicted TD point, so we started moving toward its location shown on the computer. The D-700 was also giving us the distance and direction from our location to the balloon, and we were able to make some good decisions on which roads to take once we got to highway 14. We went east for about a mile and took road 133 north.

It lead us right to the balloon and Larry and I were able to see it while it was still airborne. We droved right up to it while it was just above the ground. It landed about 50 yards to the east of the road and I was able to get several pictures, but alas, not at the right telephoto setting to see much. The parachute was not very visible while in the air, but we did see it.

The rest of the trackers and students soon arrived and we lead them all out to the TD spot. We were able to react quickly when the balloon TD point changed and we were able to get below it quickly enough to see it while in the air. We have almost done that for several flights, but we were not quite able to achieve the "under the balloon event" before this flight. It was quite a thrill to see it at this stage. The APRS equipment works well and gives us the edge to get underneath the balloon as it is descending.

We were able to take one DF bearing, but I don't think Marty had time to plot the bearings before the balloon had troubles and we remobilized for the new TD spot. We need to get Paul Ternlund's triangulation program working and use it for the bearing triangulations so Marty can be free to make the decisions he needs to in order to properly deploy the trackers during the flight.


How to Remotely Manage Predictions?

Since the prediction guy was out of town visiting family during this flight, how did he manage to still keep the group informed of his predictions. See a brief article HERE.