YC W19's @HeartAerospace just flew the largest electric airplane ever flown. Seven years ago, co-founder & CEO @AndersForslund1 came to YC with a 3D-printed model you could hold in your hand. Today, the aircraft has a 100-foot wingspan, weighs 25,000 pounds, and costs just $5 in electricity to get off the ground. YC’s @gustaf visited their pilot plant in LA to learn how they built it -- and what cheap electric flight could unlock for the future of regional air travel.