The above photos show what were officially named the "bomb bay spoilers"
Several aero-acoustic suppression devices were evaluated
at NACA, which were considered feasible for installation on A-26 Invader aircraft for flight test evaluation.
The most promising modification finally consisted of a
swing down spoiler mounted in a slot, at the leading edge of the weapon bay and between the aft cockpit bulkhead.
This device would be extended to a 90 degree vertical
position during the bay doors opening sequence.
The spoiler was rotated flush with the fuselage during
all other flight conditions. Wind tunnel tests showed that this spoiler improved the aero-acoustic environment within the
open weapon bay and improved the weapon separation characteristics over the Mach range.
The pilots of early B-26B's without the spoilers, were
advised not to open the bomb bay unless the airspeed was 240 mph or less. With the spoilers, the bomb bay doors could be opened
at high speeds up to the red-line airspeed limit.
In certain cases the spoilers would remain extended eventhough the
bomb bay doors were closed, due to hydraulic issues.
Note: On some aircraft, retractable
spoilers were fitted to the underside of the fuselage, just forward of the bomb bay in order to induce turbulence within the
bomb bay enabling the bomb to fall away, ( Sucking ), thus actually utilising "rough air" through the bomb bay as opposed
to "smooth air" to achieve the desired effect.