On 5/18/12 North Texas Near Space (NTNS-2) achieved a maximum altitude of 87959 ft over a sparsely populated section of North Texas. The flight was partially successful and full duration telemetry and camera data were recoverd.
• Vehicle departed from controlled flight, did not navigate to the landing site and was severely damaged
• Modified SW version 2.50 to utilize new AHRS code
• Modified Stinger 64 airframe
• Surface winds calm
• Trajectory was close to prediction
• Ascent was nominal
• Ascent terminated early on balloon failure at 88k ft. APM released on free fall indication and routed autopilot outputs to servos. Balloon not recommended since bursts at 86k and 88k on NTNS-1&2. 2# free lift.
• Higher than expected descent rate experienced and the plane spun down to ~17000 ft and began semi-controlled flight. The A/F managed to fly despite issues with the attitude reference and control saturation.
• Impact occured due to additional loss of reference. The roll autopilot was tracking commands.
• Maximum Mach number was about 0.5
• Minimum internal temperature was 48F.
• Airframe held up very well. One aileron horn was damaged (inconclusive considering the impact).
• Just Plain Strange: Almost crashed on my ranch. The airspeed probe is re-usable.
• Likely root case (s):
- dynamic pressure measurement low by 0.5
- gain scaling issues causing pitch and roll oscillations.
- pitch reference and finally roll reference is lost
- roll reference loss responsible for final dive
- contributing: agressive airspeed targets
• Todo:
- duplicate pitch oscillation with the stinger UAV; may need to duplicate A/S measurement issue in SW
- simulation reconstruction
- new A/F build, upgrades, noted SW changes (see spreadsheet), merge to 2.60 or latest stable build, gains
