In Detail - Drop Tanks



Drop tanks (later aircraft only):
The 45 gallon drop tanks are made of tinned steel and have a filler cap at the forward end. They are of streamlined shape and contain two baffles. The drop tank attachment brackets and stabilising brackets are bolted to the tank in the locality of the baffles, and the assembly is stiffened internally by top-hat section channels which extend for the full depth of the tank and are bolted to the baffles.


The bolts fixing the drop tank attachment brackets to the tank pick up with flanges at the top of the internal stiffener channels. A roller on each attachment bracket engages with the hooks in the wing and, when the tank is in position, the open side of the front hook is closed by a paw1 in the release unit. The paw1 is locked when in the closed position by a spring-loaded latch, and the latch, in turn, is operated by a spring-loaded trip lever which is connected by a bowden cable to the jettison control in the cockpit. When the jettison lever is operated the trip lever is pivoted upwards against the action of its spring. This causes an arm on it to bear against the latch, pushing the latch upwards and so releasing the pawl. The tank then slides out of the hooks under gravity, pushing over the paw1 which is free to rotate about its pivot. An indicator arm carried on the latch protrudes below the wing skin, when the tank is locked in position. As the tank falls away it breaks the glass tubes of the fuel delivery and air pressure pipes. The tank fairings are made of light alloy, though some may still be of transparent acetate sheet.


They are made in four sections and are attached to the stabilising brackets on the tank, 20 s.w.g., light-alloy joint plates being provided at the attachment.points. Along the top of the fairings is a doubled-over strip of felt which seals the gap between the fairings and the undersurface of the wing when the tank is in position.

Drop tanks jettison lever and air pressure control:
The jettison lever and air pressure cock control lever are mounted together in a control box on the starboard leg panel. A lug on the jettison lever engages with and pushes back the air pressure cock control lever whenever the former is pulled back to the JETTISON position, thus cutting off the pressure supply to the drop tanks immediately they are jettisoned. The jettison lever must be retained in the JETTISON position whenever the drop tanks are not fitted, or a breakdown in the air pressure system will result.