The Dash 80 was the prototype for the 707 passenger jet and the KC-135 jet tanker and was the first member of the "700" family of commercial and military jets. The Dash 80 prototype had few windows and no seats, but had two large cargo doors because it was constructed to sell first as a military-tanker transport. A week after its first flight, the Air Force ordered 29 tanker versions, the KC-135.