enginehistory.org

[hfriedman]

As the story goes: In the spring of 1941 Lieutenant Commander John S. Thach, skipper of Fighting Three learned that his likely adversary would be the Mitsubishi A6M “Zero” that outperformed the Navy’s F4F Wildcats. Thach set out to devise defensive tactics, eventually developing the famous Thach Weave.

“In order to best approximate the superior performance of the Zero, he took a pair of two-plane Wildcat sections and modified heir throttles so that they could only obtain two thirds of their engines' potential power. These would play the role of the aircraft to be attacked. Attacking them would be two pair of Wildcats, with full use of their throttles.” [McCullough, Escort at Midway (Airpower Magazine May 19940]

These were probably F4F-3s with R-1830-86 or possibly R-1830-76s. But there is something strange about this story. It seems inconceivable that the Navy would have permitted depriving the fighters of a third of the power available for take-off and waive off.

Is it possible that full throttle travel was not available at sea level anyway without exceeding allowable manifold pressure so that the restriction was only effective at altitude?

Comments anyone?

[jjuutinen]

Well, in most early war American engines there were no automatic boost controls which made overboosting at sea level very easy. Remember the tests of some US aircraft vs. A6M2? The P-39D drew 70 in MAP on take off before kncking forced the reduction of boost. Max allowed boost in the P-39D´s engine was around 52 in at that time.