Boeing Co. views the low-ball bids that helped it win contracts for a Navy drone and an Air Force training jet as spending money to make money.

While the Chicago-based planemaker wrote down third-quarter profits in its defense unit by $691 million to cover costs on initial work for the MQ-25, an unmanned refueling tanker that can take off and land on an aircraft carrier, and the T-X trainer for Air Force fighter pilots, Chief Executive Officer Dennis Muilenburg says the two programs offer a potential $60 billion long-term revenue stream.