We didn't get a chance to include all the articles we wanted to this month, including from Marty Potts, Ed Rothermund and Charlie Anderson (on behalf of his Dad, Milton Anderson).   We've been so busy gearing up for the meeting next month at the Planes of Fame near the Grand Canyon that time just got away from us.  Promise we'll get to those in the next issue!

P-38 HARDSTAND
by John Stanaway

The Diving P-38

One of the most misunderstood of all performance features on the P-38 was its dive characteristic.  Almost from the beginning of its service life in 1940 the P-38 earned a reputation as a devil in the dive.  Later, when it began high-altitude service in the Mediterranean and Europe there was a mystic fear among crews who had to operate the fighter above 24,000 feet.

The phenomenon of compressibility was new and little understood when the sleek P-38 was among the first to encounter it.  Technical design features of the P-38 included an unusually streamlined configuration that allowed the fighter to slip through the air with almost no resistance from the flow over its airframe.  Most fighters of the period had large frontal areas or ample fuselage sides to catch surrounding air and slow the aircraft enough to avoid reaching the critical airspeed which would overwhelm design limits.  The P-47, some pilots claim, would react even more violently when it reached its threshold of compressibility, and the P-51 with its laminar flow wing did not reach compressibility until a very high dive speed was reached.

This force called compressibility was really just the inability of the airflow to negotiate the design limits of an aircraft and provide lift after the wing was moving through the air too swiftly to allow the molecules of air to provide upward pressure on the underside.  Lockheed designers quickly understood that somehow they must slow the P-38 down and at the same time jam up the air molecules under the wing to provide sufficient lift for dive recovery. 

Pilots in the field understood the problem and its possible solutions.  Our good friend and successful South Pacific P-38 pilot, George Chandler, used such means as the opening of intercooler flaps to slow the P-38 down enough to effect recovery.  I asked him if putting the propellers in fine pitch would help to slow the P-38 down, and he answered that it perhaps would, but the P-38 pilot who was recovering from a dive would want all the pull his prop blades would deliver to get the nose of the fighter up towards the horizon.  The same was true about elevator trim, in that forces on the tail would build up to the point of overstressing the booms, perhaps wrenching them off at the critical point of recovery.

Lockheed found the final although compromised solution in recovery flaps added to the outer underside of the wings.  The small rectangular flaps would both slow down the aircraft in a dive and provide a break to jam up airflow enough to provide lift on the forward edges of the wings of the J-25 production block, and subsequent L-1 and 5 models.  What resulted was something that dived so well that Lockheed claimed the P-38 would out dive everything except the “mystic German rocket fighter.”  Unhappily, this felicitous development in the P-38 came along just a bit too late for the European war.  The P-38 was transferred out of the 8^th Air Force by the end of September 1944, and it would see little high altitude service afterward when it saw action with the tactical 9^th Air Force at lower heights.  However, when the later models with the new flaps and power-assisted ailerons saw action they gave sterling service.

John Stanaway is a world-renowned aviation author,
including his newest one on the "479th Fighter Group"
(Riddles Raiders) . Check it out here.

DONATIONS

We thank all of those who have showed that extra measure of support for the P‑38 Association by sending in their generous donations during the past month.  Much appreciated!