Historical Notes on Cards, Part 3

British Cards

CARPET: The American-made APT-2 jammer, codenamed ‘Carpet’, was not used as extensively as in the US Army Air Forces but nevertheless provided jamming support for Bomber Command against flak gun radars.

JOSTLE IV: Jostle proved to be one of the most powerful airborne jammers deployed in the war and was capable of spot-jamming all VHF communications between the ground and air. Only the highly encoded BERNHARDINE system may have stood a chance against the transmitter.

PHOTO: The Jostle IV was built on the say-so of Dr. Robert Cockburn of the Telecommunications Research Establishment without passing through official channels. Once Cockburn's bosses received the half-million pound bill for the jammer, ordered with no authority or finance, he was given an 'Imperial rocket'. However, the Jostle turned out to be a formidable apparatus. Housed in a huge pressurized dustbin (to prevent arcing), with additional generators needed for power, it radiated 2 kW of continuous noise jamming across the 38-42 MHz VHF band used by the Luftwaffe. The 600 lb bulk of the jammer was fitted into the bomb bays of Royal Air Force Flying Fortresses.

FULL THROTTLE: On the route home bombers, lightened of their bomb load, could make better use of their speed to avoid danger.

DOGLEG: Sometimes a small course change was added to a raid’s flight plan simply to confuse the defences.

DECOY FLARES: To aid navigation of the bomber stream, pathfinders dropped flares at key navigation points along the route. When Bomber Command learned that the Germans were using these to find the bomber stream, they began to use different coloured decoy flares to fool them.

SOUTHERN GERMANY: Gaps in the southern German radar and reporting network could sometimes work to the British advantage.

LOW FUEL & AMMO: Combat and extended operations would soon cause nightfighters to break off for home.

FUEL FAMINE: As the war ground on, a lack of fuel would keep aircraft grounded. Increasingly, priority for fuel resources would be channelled to veteran units and Experten, who would be kept flying at all costs.

PHOTO: The contribution of the Mosquito bomber to Bomber Command's night offensive is difficult to overstate. Its mere presence was enough to drive the Germans into a panic. Though its contribution in terms of tonnage dropped was a pinprick compared to the 'heavies', its ability to perform diversionary attacks or harassing raids on airfields was of enormous value. Its speed meant that it was rarely caught by nightfighters and the Germans expended huge resources fruitlessly trying to deal with the Mosquito menace.

FLOWER: ‘Flower’ was the codename used for Mosquito raids intended to disrupt the operation of nightfighter airfields.

ACCIDENT: Another benefit of the FLOWER raids was that they could catch nightfighters when landing or scare airfield commanders to limit the availability of landing strip illumination. Many accidents were forced in this way.