(underside) armour. Only the armour plate for the rear gunner needed to be manufactured and the extra armour was ordered to France as soon as possible. Battle fuel tanks were to be given the French coating, which easily plugged holes from rifle-calibre bullets and also gave some protection from fire. would use up the allotted for fuel tank protection and was still under test but of armour plates were added to the rear of the tanks against hits from behind. On 18 December, twenty-two Vickers Wellington bombers were sent to attack German ships in the Battle of the Heligoland Bight and eighteen were lost, many shot down in flames; some of those not shot down ran out of fuel from punctured fuel tanks. The fitting of self-sealing tanks became a crisis measure for Bomber Command and took precedence over the Battle modification, especially as their existing tanks had been armoured against hits from behind and the conversion was put back to March 1940. The extra armour decided on in September was apparently sent to France but never fitted to the Battles. Operational instructions issued by BAFF included a warning that The RAF had tried to improve the performance of its aircraft; streamlining the Blenheim had added to its speed. To remedy the vulnerability of Battles to attacks from below, a rear-facing machine-gun was fitted to the bomb-aimer's position but "...it needed a contortionist to fire it....", Fairey designed a well in the floor of the bomb aiming position for the gunner to lie prone facing the rear but the change would need three months for development and testing. With in storage, the modifications could be done at Fairey and the aircraft swapped with those in France without interfering with AASF operations but the idea was shelved. To speed production of new aircraft, a review was held to strip existing machines of superfluous equipment and the committee suggested that for tactical bombing, the Battle autopilot [], night flying gear [], bomb sight [] and the navigator–bomb-aimer [] could be dispensed with, saving , which would allow the fitting of more forward-firing guns with no net increase in weight. The Air Ministry prevaricated and the equipment was not removed, the Ministry even deprecating the use of the existing forward-firing gun, which was supposed to be reserved for engagements with German fighters, not for strafing unless circumstances were exceptional. October–December On 11 October,