The article stated that the Ultralight, with two people on board, failed to gain sufficient altitude after take off. Maybe it was over loaded and/or the pilot was pulling back on the stick, trying to get it to climb, but succeeded only in putting the aircraft into a nose high attitude? That's pure speculation on my part, but in my early experiences with flight sims I'd often haul back on the stick in an effort to climb. The end result was usually no gain in altitude or a stall.