Flight Testing: HAPP-T3

After some software trouble on the last test flight, HAPP-T2, we finally got some decent weather in Michigan and were able to run HAPP-T3. This is (probably) the last test flight before the first full mission, HAPP-M1. 

Many thanks to the terrific ground crew who showed up to help. Derrick, James, Ted, Mike, Tyler... you rock!

The video tells most of the story so please enjoy it when you have a few minutes to kill. Some notes regarding non-obvious points:

  • Winds versus flight plan.  The forecast called for 4 mph winds. In the morning the sky was indeed calm. However, by the time the balloon was inflated (and we were "committed" with more than $400 of helium already inside a $150 single-use balloon), the winds had picked up significantly. Winds were even worse a few hundred feet off the ground. Because of this, we abandoned the original plan to ascend 300 meters and perform a drop test, as there's no telling where the HAPP might have drifted once the parachutes deployed. We retracted the tethers, brought the HAPP back down, and fired the parachutes on the ground.
  • Performance.  Despite the howling winds, the jet stabilization was able to null out the spins pretty easily - and the jets were only set to 2/3 power. "Why was the HAPP not fully stabilized the entire flight? This is supposed to be a stabilized platform!" you might wonder. Well, thanks for asking. The onboard computers monitor altitude, spin rates, and jet gas remaining. Fighting against low-altitude winds and then the jet stream would be a waste of gas. To ensure we have some gas left in the tank at apogee (a.k.a. the money shot), the software cuts off the stabilization at various thresholds. In addition, the software will tolerate a bit of spin at low altitudes, and then gradually tighten up the stabilization as we reach target altitude.
  • Altitude.  Max altitude in this flight was 120 meters AGL.
  • Ascent rate.  Immediately after release the balloon climbed freely with minimal pull from the ground tethers. The ascent rate was about 650 feet per minute. Normally I'm a metric system guy but we track feet per minute because that's what the FAA wants to know when we file our flight plans. You may convert to the system of your choice (parsecs per Planck time would be fun).
  • Telemetry.  We did uncover a bug in the software library we're using for the satellite modem. This resulted in large delays for uplink / downlink messages. It appears to be an easy fix and should be OK now. That's why we test.
  • 360 Video.  With a VR headset it looks awesome! The YouTube video above is not 360 - just a normal 4K video - but I included some of the 360 footage by flattening it into a funky field of view. Tech note: I captured video on the Garmin VIRB 360 in 5.7K mode and performed the 360 stitch on my PC in post-production. I can definitely see the improvement of 5.7K 360 over 4K 360 in my Oculus Rift. Fortunately, YouTube allows 5.7K now - if your PC can play it back without choking :-)

The main mission, HAPP-M1, is only a few weeks away. Stay tuned!