Launch Window - Definition: How and When We Choose To Launch
Decision: Dec.1 – Mar. 31 for local Launch Window
• Fact or Opinion: Northern hemisphere winter will be the ideal flight conditions
• Fact or Opinion: Low sun angle in winter
• Fact or Opinion: Winter in Northern Hemisphere is good for longer flights
Critical: Jet Stream predictions
• Issue: Need the ability to predict when Jet Stream will be right for insertion.
• Investigate: Base upon NOAA models
Consideration: Optimal launch time is just after sunset.
• Fact or Opinion: Just after sunset optimizes for maximum flight time. The idea is to launch as far before sunrise as possible. Reaching float altitude in the dark allows the helium to be densest when it overflows out the vent. Then at dawn, the sun heats the helium and it expands, with some flowing out of the vent, maintaining altitude.
Consideration: Select a launch time that that does not let the flight path cross major metropolitan cities, such as Washington, D.C. or New York City.
Consideration: Anything other than complete calm wind will severely degrade the accuracy of vertical lift force measurement.
Proposed Criteria: Winds -
• Proposal: Safe maximum 5MPH
• Proposal: Technical maximum 10MPH
• Safety: Higher than this are likely to damage balloon or injure people holding balloon.
Proposed Criteria: Temperature - Any is acceptable.
Proposed Criteria: Barometric pressure – Any is acceptable.
Proposed Criteria: Visibility –
• Proposal: Clear sky for airplane safety
• Proposal: Balloon should not enter clouds(subjective)
Fact or Opinion: When the Jet Stream is ready for balloon insertion, it will be one of the coldest nights of the year.