iMet-4 Radiosonde

Overview of instrument and launch guide

Link to Technical Data Sheet

https://www.intermetsystems.com/wp-content/uploads/2022/01/202084-12_iMet-4_Technical_Data_Sheet.pdf

The iMet-4 radiosonde has 3 sensors and 4 derived parameters:

• Temperature: Sensor
• Humidity: Sensor
• Pressure: Sensor
• Pressure: GPS derived
• Geopotential Height: Pressure derived
• Geopotential Height: GPS derived
• Wind Speed & Direction

Instrument Specifications:

• Weight: 120g
• Dimensions: Body 139x67x31, With instrument boom 235x67x31
• Calibration Shelf Life: 2 years
• Operating Time: >135 minutes
• Battery Type: lithium ion
• Max Range: >250 kilometers

This is just a general guide to a typical iMet-4 launch. It should not be your only resource and should not be done without supervision. It is formatted in chronological order but some steps might take longer or shorter than posted here. Always build 15-30 extra minutes into your launch time so that unforeseen issues can be resolved without rush. Never attempt to launch by yourself, always have 2-3 people present.

• 1 hour before launch
• Clifford hall garage and lab 423

1. Prep balloon fill and launch area. Remove any vehicles from garage, sweep floor and lay tarp down on floor of area beside helium tanks.
2. Gather required materials on bench by garage door:
   1. Snips
   2. Pack of zip ties
   3. 12 inches of string
   4. 1 parachute
   5. 1 dereeler
   6. 1 200g balloon
   7. 1 iMet-4 radiosonde
   8. 3 pairs of disposable gloves
3. Gather required helium tools on helium rack:
   1. Adjustable wrench
   2. Gas regulator
   3. Gas hose with nozzle
   4. 1 pair of work gloves
4. Weigh payload
5. Calculate amount of gas needed to achieve 5m/s lift
   1. Typically this is double the weight of the payload
6. Find wrench or other weight that is correct for payload
7. Attach gas regulator to least full gas container
   1. Ensure that tank is secure to wall
   2. Remove protective shield over tank nozzle
   3. Close gas regulator
   4. Attach gas regulator to tank
      1. Gas regulators have reverse thread
   5. Tighten gas regulator using adjustable wrench
   6. Point hose nozzle in safe direction
   7. Open tank slightly to check for gas
   8. If no gas is present
      1. Remove regulator from tank
      2. Reattach shield
      3. Place tank on empty side
      4. Label tank empty on whiteboard
   9. Repeat until gas is detected
8. Attach weight to hose nozzle
9. Remove parachute and dereeler from package and detangle
10. Attach dereeler to parachute bottom with zip tie
11. Snip all zip ties at knuckle so that they do not interfere with balloon

• 15-30 minutes before launch
• Clifford Hall room 601

In Clifford hall room 601, the computer closest to the outside door is the iMet computer

1. Bring radiosonde from garage to computer and turn on
2. Turn on computer and open skysonde server and skysonde client
3. Change flight name to time of launch
4. Set frequency between sonde and computer to same frequency
   1. Typically 402MHz
5. Check for data incoming to server
6. Bring sonde downstairs to garage and set outside to calibrate

• 10-15 minutes before launch time
• Clifford hall garage

1. Bring hose nozzle to center of tarp
2. Put on disposable gloves
3. Grab materials
   1. Snips
   2. 4ish zip ties
   3. 200g balloon in bag
4. Carefully unwrap balloon and place neck of balloon on hose nozzle
5. Hold balloon firmly on nozzle and open gas hose
6. Stop gas when balloon is neutrally buoyant with weight
7. Tie balloon neck tightly above nozzle
8. Remove balloon from nozzle
9. Tie top of parachute to balloon neck
10. Fold over remaining neck
11. Zip tie folded neck together
12. Snip zip tie at knuckle
13. Have two people hold balloon apparatus
    1. One person holds the balloon
    2. one person holds the parachute
14. Open garage door
15. Attach radiosonde to dereeler with zip tie
16. Snip zip tie at knuckle and bend instrument boom slightly away from flat back of iMet-4
17. Now with at least 2 people holding apparatus
    1. One person holding balloon
    2. One person holding iMet-4
    3. (Optional) one person holding parachute
18. Move outside as one unit
19. Adjust launch zone for surface wind
20. Release balloon, allow parachute and radiosonde to be taken from your grasp
21. Go back to Clifford hall room 601 to view sounding data as it comes in