Hughes H-4 Hercules The H-4 only flew once. It was made out of spruce wood, and earning itself the nickname "Spruce Goose". As you can see in the picture, it was a sea-plane. It had four giant propeller engines, to help it fly. During World War II, transport boats would be sunk by submarines. So Howard Hughes made the Hercules To take supplies and soldgers over the water. But it was not completed by the time of war. It now lies at the Evergreen Aviation & Space Museum. It still holds the record for the longest wingspan.