Passage: On his first day, Armstrong was tasked with piloting chase planes during releases of experimental aircraft from modified bombers. He also flew the modified bombers, and on one of these missions had his first flight incident at Edwards. On March 22, 1956, he was in a Boeing B-29 Superfortress, which was to air-drop a Douglas D-558-2 Skyrocket. He sat in the right-hand pilot seat while the left-hand seat commander, Stan Butchart, flew the B-29.As they climbed to 30,000 feet (9 km), the number-four engine stopped and the propeller began windmilling (rotating freely) in the airstream. Hitting the switch that would stop the propeller's spinning, Butchart found it slowed but then started spinning again, this time even faster than the others; if it spun too fast, it would break apart. Their aircraft needed to hold an airspeed of 210 mph (338 km/h) to launch its Skyrocket payload, and the B-29 could not land with the Skyrocket attached to its belly. Armstrong and Butchart brought the aircraft into a nose-down attitude to increase speed, then launched the Skyrocket. At the instant of launch, the number-four engine propeller disintegrated. Pieces of it damaged the number-three engine and hit the number-two engine. Butchart and Armstrong were forced to shut down the damaged number-three engine, along with the number-one engine, due to the torque it created. They made a slow, circling descent from 30,000 ft (9 km) using only the number-two engine, and landed safely.Armstrong served as project pilot on Century Series fighters, including the North American F-100 Super Sabre A and C variants, the McDonnell F-101 Voodoo, the Lockheed F-104 Starfighter, the Republic F-105 Thunderchief and the Convair F-106 Delta Dart. He also flew the Douglas DC-3, Lockheed T-33 Shooting Star, North American F-86 Sabre, McDonnell Douglas F-4 Phantom II, Douglas F5D-1 Skylancer, Boeing B-29 Superfortress, Boeing B-47 Stratojet and Boeing KC-135 Stratotanker, and was one of eight elite pilots involved in the Parasev paraglider research vehicle...

Question: Who piloted chase planes on the first day?
Armstrong