Recap of EOSS-85

LAUNCH DATE: October 16, 2004
LAUNCH TIME: 10:28 am MDT (16:28 UTC)
LAUNCH SITE: Meadow Lake Airport, CO (directions here)

EOSS-85 Track

Blue = Actual Track
Green = Predicted Ascent Phase
Red = Predicted Descent Phase

Maps made with MapPoint
Prediction made with Balloon Track

Launch Site - Meadow Lake Air
Launch Point: 38.9527� lat.   -104.5752� long.
Ascent Rate: 1000 feet per minute
Descent Rate: 900 feet per minute
Altitude: 6874 feet
Predicted Landing Site
Landing Point: 38.3487� lat.  -102.7886� long.
Altitude: 4900 feet
Flight Time: 129 Minutes
Bearing: 112.8� True
Range: 105.0 Mi.
Actual Landing Site
Landing Point: 38.6825� lat.  -103.4683� long.
Bearing: 107.0� True
Range: 62.4 Mi.
Difference from Predicted to Actual Landing Site
Bearing: 302.3� True
Range: 43.4 Mi.

EOSS Frequencies:

Global Frequencies

  • Tracking and Recovery Operations
    • 146.970 MHz PPFMA Repeater(100 Hz Tone)
    • 146.550 MHz simplex (same simplex for field and launch ops)
    • 7.228 MHz HF (sporadic usage)
  • HF Net
    • 7.228 MHz
      • Net Control: KA�DPC - Sparky Ulmer


  • Cross Band Repeater
    • Input: 445.975 MHz
    • Output: 147.555 MHz
    • ID: W�WYX
  • Beacon
    • 145.600 MHz
      • ID: W5VSI in CW
  • APRS
    • 144.340 MHz (Payload Train)
      • ID: K�ANI-11
      • DIGI: none
    • 147.555 MHz
      • ID: W�WYX
  • ATV
    • 426.250 MHz (AM Color)
      • ID: W5VSI

Flight Systems:


Balloon Manufacturer Scientific Sales
Balloon Type latex
Balloon Size 3000 gram
Payload 12 lbs
Free Lift % 20%
Ascent Rate 1248.75 fpm average
Descent Rate -1196.47 fpm average below 10K
Parachute 5 ft. diameter
Peak Altitude 77,480 ft ASL
Launch Conditions Good Winds 6-8  Filled in Hanger

Payload Configuration:

Tracking and Recovery Info:

EOSS Grid:

Location Grid X Grid Y
Punkin Center 1 64
Haswell 30 36
Eads 51 38
Wild Horse 39 62
La Junta 9 4
Predicted Touchdown 55.6 26.8
Launch -46 71

Tactical Callsigns:

Tactical Callsign Name Notes
Alpha N�NDM and W�CBH Larry and Benjie coordinator
Bravo WA�GEH Marty coordinator
Charlie KC�RPS  and W�NFW Jim and George  
Delta KB�YRZ and K�ANN Chris and Ann  
Echo none    
Foxtrot none    
Golf none    
Hotel none    
India N�LP Nick Ground Station
Juliet none    
Kilo none    
Tango NQ�R Randy Telescope

Internet Gateway Stations:

as seen on Findu.Com


  • K�YG-7 - Mark Patton
  • KC�LNO - Mike Skinner

For K0ANI-11

  • K0YG-7 - Mark Patton

Known to be attempting but didn't make it onto

  • WA�VSL - Doug Wilson

EOSS wishes to express our sincere appreciation to the stations above who iGated the balloon APRS telemetry onto the internet.

We are relying heavily on real time position information available on the net to allow the FAA controllers to have up to the minute location data to assist them in air traffic control.

Redundant stations for the balloon iGating provide excellent coverage. If you are able to iGate we invite you to join the Internet Gateway Team. Contact me ( to be put in touch with the coordinator. By joining the team, you are giving peace of mind to the iGate coordinator for that flight. He knows you'll be there and he can rely on you.

Naturally, anyone can iGate data onto the net and even if you aren't a member of the team we will welcome your contribution to the internet based tracking effort. If you callsign appears on the log, you'll be shown as a contributing station as those above are.

Having more than one station covering each APRS beacon means that should a station drop out momentarily, the others maintain the data flow quite nicely.

Thanks again guys! The FAA (and EOSS) are very grateful for your assistance in this endeavor.


Launch Site:

Recovery Site:


Randy Renard [NQ�R] had his telescopes mounted with a B&W camera and video recorder. He caught the burst on video.

The balloon's location data at burst was:

  • Altitude: 77,480 ASL
  • Latitude: 39� 47.97 N
  • Longitude: 103� 55.090 W
  • Distance from Launch Site (telescope): 36.9 miles
  • Bearing from Launch Site: 106� True
  • Elevation from Launch Site: 20�
  • Course (track) just prior to burst: 57�
  • Speed just prior to burst: 10 MPH


  • Burst Normal (901KB) - Normal motion and full frame with contrast enhancement.
  • Burst Slow Zoomed (690KB) - Half speed slow motion and zoomed in on the balloon.
  • Ascent (1.4 MB) - Normal motion and full frame with contrast enhancement. This brief clip shows the balloon ascending behind clouds and Randy's tireless efforts at maintaining a visual lock while maintaining lock (manually) on the balloon with the telescope.


Most likely, no audio will be posted. There just isn't that much traffic. However, if someone requests it, I can edit it and post. I have audio recordings of the T&R repeater and the airborne cross band repeater.


Data files are concatenated data from my home station (N0KKZ) and the Findu.Com logs. If more data becomes available to flesh out these files I will edit them and post updated logs.

W0WYX (updated 10-19)







Ascent phase only for both charts.



Tracking and Recovery Perspective

by Benjie Campbell, W�CBH

What a day we had.

We were short of trackers this flight. Larry Noble (N0NDM) and I (W0CBH) rode together to reduce fuel costs and tracking chores while in the field. We have discovered it takes two people to do all the things we force ourselves to do while tracking the balloons. We have so many toys to play with it takes two to do it.

We left my house at 4:30 am and headed to Limon, CO where we met the other three trackers for an early breakfast at the Denny's. All of us then headed south to Eads, CO to disperse to our assigned locations.

While enroute, we learned the launch team had delayed the launch due to fog, yes, fog. We were in bright sunshine, and they were fogged in.

We more time to find to find our tracking locations and were able to start the computers and adjust all of our toys before the balloon launched. We had time to use Nick's Grid Calc program to obtain each trackers reported position from their APRS beacon. Each tracker reported their grid location from their various methods of determining them to the coordinator. I then input their call sign into the balloon track section of Grid Calc and it received their next beacon and reported the grid location from the gps data contained in that signal. I then compared that data with the grid they had reported earlier. We were really bored waiting for the launch, what can I say?

We were all close enough to hear each others aprs beacon on 144.34. Larry and I only used one computer this flight instead of two, and it worked well. We had planned to take several signal bearings during the flight but we found we were too busy playing with the cross band repeater and the other toys so we didn't take any reports from the trackers.

The APRS from the balloon was working well on one of the two aprs beacons at our location. The K0ANI-11 beacon wasn't decoding well so we used the W0WYX beacon which worked fine 95 percent of the flight. Grid Calc gives a lot of useful data as it decodes each packet from the balloon beacon.

After the balloon burst we were able to use that data to vector the trackers into the landing zone. The balloon landed 0.9 miles from the nearest road in an unfenced field. So six of the seven trackers were able to walk in and retrieve it fairly fast.

We then drove back to Limon for a great lunch and discussion of the flight and recovery.

On our return to town we heard Mike (W5VSI) say that an aircraft reported a near miss with our balloon at 41,000 feet during the ascent.

Prediction Perspective

by Rick von Glahn, N�KKZ

As I'm sure of the cognizance of the tracking and recovery teams regarding the slight error in predicting the touchdown location (43 miles off), I thought I'd "explain" myself to others. :-)

Essentially two major factors and one minor one contributed to a significant prediction error.

1.) The balloon's ascent rate was substantially higher than anticipated.

2.) Incorrect descent rate used in predictions.

3.) The balloon burst at 77K feet instead of 95K feet.

As you can see from the above graphs, the balloon's ascent rate was between 1000 fpm and 1800 fpm. Note also that the highest ascent rates occurred early in the flight below approximately 51K (1392.7 fpm as opposed to the predicted 1000 fpm). That is also the section of the atmosphere with the highest wind speeds.

The balloon charged through the highest wind speed layers much faster than expected thus greatly shortening the overall distance of the flight. This was the strongest factor in the much shorter trajectory. Even if the balloon had managed to remain intact and ascend to 95K, the extra flight time in the much lower speeds at high altitudes would have impacted the total track length only slightly.

The post burst prediction was sort of OK. The error there was 5 miles. The descent rate was faster than I had allowed for. However, this time the fault lay with me rather than the weather gods.

In my calculations for this flight I had plugged in a descent rate of 910 feet per minute (sea level). This is a good rate to go with when flying around 25 pounds of payload under a 10 foot chute. However, we were flying approximately 12 pounds under a 5 foot chute. I don't know what I was thinking but I never calculated that load and thus missed the fact that it was expected to descend at 1244 fpm. This descent rate would have brought the prediction much closer to the actual in the post burst prediction and would also have chopped off approximately 11 miles from the pre-flight prediction.

So, all in all, this wasn't the best day for the prediction shack.

Congratulations to the T&R Teams for working around the problems I introduced. I'm just grateful that we had good APRS for this flight or it would have been a much tougher task for the recovery guys.


Our Customer

This was a pro bono flight by EOSS in support of the Scouts Jamboree on the Air.