Conquering the Sky!

Air Classics, Apr 2005 by O'Leary, Michael

On 31 December 1938, the completed XP-38 was taken by truck from Burbank to March Field, near Riverside, California. The lengthy journey was made in some secrecy and the partly dismantled aircraft was shrouded to prevent prying eyes from getting a close look. It took several days to assemble and seravice the machine and make sure all systems were operational.

During the first series of taxi tests, Kelsey found a number of problems - one of which almost resulted in the loss of the prototype before it had flown. As speed was increased it became apparent that the XP-38 lacked sufficient braking power. The brakes became extremely hot on one high-speed run, and the XP-38 shot off the end of the paved area, bounced through the grass, hit a ditch, and stopped. By the time Kelsey had clambered from the cockpit, Lockheed engineers had already arrived. The frightened team inspected their creation, feeling the polished skin for evidence of any structural deformation. After a quick walk-around, they were delighted to find no damage.

Engineers scavenged the limited spares bin for useful items, and attached a cylinder from a Northrop A-17 dive bomber and an extra small tank to contain additional hydraulic fluid inside the XP-38 so that, when the brakes began to fail, the pilot could pump additional fluid into the brake reservoir to provide increased brake pressure and cooling.

Kelsey and Lockheed realized that the brakes would be good for only one or two landings with this emergency lash-up. The pilot decided that the best way of getting the XP-38 back to its parking space would be to bring the big fighter in over the fence at the slowest possible speed - right on the edge of the stall - allowing the plane to use the entire runway to stop with minimal braking. Kelsey and the Air Corps, both entering a new phase of high-performance aerodynamics, were to learn that dragging an aircraft in over the threshold at very low speed was unwise and unsafe.

The modification work was completed on 27 January 1939, and the XP-38 was brought out for final checks. Kelsey boarded the prototype, went through a brief engine check and began to taxi toward the runway, using the rudders for directional control and staying off the brakes as much as possible. Slowly advancing the twin throttles with his left hand, he decided to go after rolling a short distance. Speed quickly built and a tug on the yoke lifted the nosewheel and the XP-38 smoothly lifted from the March runway, the roar of its twin Allison a muted rumble as the exhaust gases passed through the turbosuperchargers. It was not to be a smooth flight.

Just after the main-wheels left the runway, flutter set in, the instrument panel disappearing in a violent blur. Kelsey fought to maintain control with the yoke that was trying to shake itself out of his hands. A quick glance out of the cockpit showed the wingtips were shaking so violently that they were traveling 3-ft up and down!

Kelsey yanked the flaps up. The large Fowler flaps had been half down, a takeoff procedure recommended by Lockheed engineers. As they came up into the wing, the intense flutter stopped. Reducing speed, Kelsey flew the XP-38 for 34-mins, making the gentlest of maneuvers while trying to figure out why the fighter had nearly shaken itself to pieces. During the intense flutter, the pilot had noticed of portion of the flap shaking particularly violently. The fact the flutter disappeared when the flaps were retracted led him to attempt a landing with the flaps fully up. Since they had to stay up, Kelsey was forced to keep the fighter's nose up 18-deg during the approach and the twin fins contacted the runway before the mainwheels.