Heavy bombers, in the opinion of S/Ldr Salter, appeared to be cursed. Sometimes the A&AEE tested them and found them wanting. Sometimes they only revealed their faults after entering service. But for whatever reason, every one of the heavy bombers that British industry had produced had failed to live up to the manufacturers' exuberant promises. While the fighters astounded everyone with their performance, while the medium bombers at least did what they were built to do, the heavies just — didn't.
First there was the old Whitley. Slow, lumbering and inaccurate, probably the most useful thing it ever did (in Salter's opinion) was keep the Germans supplied with toilet paper back when we thought dropping leaflets was a good idea. Then the Manchester, with its Vulture engines — which kept throwing their bearings and seizing up. Air Ministry was considering grounding them until something could be done about it; last he'd heard, half of 207 Squadron had gone back to flying their old Hampdens instead.
The Stirling, now, that one had looked promising for a while. Handily manoeuvrable even with six tons of bombs on board, but the performance at altitude was poor, the radius of action wasn't too good, and the less said about that damned undercarriage the better. Between the landing gear and the throttle controls, the Stirlings seemed to spend more time in the hangars than out of them. Still (he had to admit), the crews seemed to like it, at least when it was working. Maybe the sheer size of the aircraft gave them a feeling of power.
And now the Supermarine Mitchell and the Handley Page Halifax were lined up for testing; the former for development flying and the latter for its service trials. He hadn't found any flaws in the Halifax — yet; he was sure something would show up sooner or later — but the Mitchell's limitations were (to him) glaring. The engines weren't developing their design power — they'd been de-rated to deal with various issues, and the inboard pair had then been de-rated further because of some problem with cooling — and the airframe was overweight. The much-vaunted 21,000lb payload had been cut back and it looked like they'd be lucky to match the Stirling on that front. And it still had a fairing on the nose where the turret was supposed to be — Fraser-Nash had been having difficulties working around the quirks of the Mitchell's hydraulic system, and still didn't have an installation ready. When it came, it was bound to add yet more weight to the bomber, and cut into payload even further.
It wasn't all doom and gloom, though; Supermarine's changes to the flap profile had made the trim behaviour much better, and the servo rudder — while it looked a little old-fashioned — was working well enough. Whatever its failings as a weapon of war, the Mitchell was at least a 'pilot's aircraft', pleasant to fly. He called to his flight engineer, sitting across the Mess. "Hey Bairstow, shall we make a move on those engine handling tests? I thought we'd do the Mitchell first, if that's OK?"
"Sure thing, skipper."
"The Bristol Hercules," ran a Ministry of Aircraft Production technical report, "while adequate for initial working-up of the Supermarine Mitchell, lacks the growth potential the aircraft's development will require. Achieving a satisfactory performance will require engines in the 2,000hp class, which lies beyond that realistically achievable by the Hercules."
The report went on to recommend that Napier's 'H' engines be used, first the Dagger VIII in a resuscitation of the earlier Supermarine Type 316 concept, this paving the way for the development of a Sabre-engined version, the Type 316B. "Such an aircraft," the report continued, "would meet or exceed the original performance projections of the Type 317 on all axes. It must however be noted that the supply of Sabres would, initially, prove a limiting factor; volume production of the 316B would necessitate the opening of a Sabre production line at a shadow factory."
Lord Beaverbrook finished reading the report, and reached for the 'phone. "Fraser?" he spoke into the instrument. "I'm not happy with this Mitchell proposal. Hawkers never stop telling me about the trouble the Napier engines are giving with the Typhoon. Give me options."
"I suppose there's always the Vulture," replied the Director-General, Eric Fraser, "but if you think the Sabre has problems–"
"–the Manchesters are even worse, I know," the Minister interrupted. "It's a scandal. Are you sure we can't get more out of the Hercules?"
"Well, Bristol are offering the Centaurus, but that won't be ready for at least a year, probably more. Supermarines did say they needed wind-tunnel time to improve the 317's cowling, they hope to get at least another 75hp out of each engine that way, so that's an interim option."
Beaverbrook was a decisive man, and it didn't take long for him to formulate a plan. The Hercules cowling work would be given priority on the Farnborough wind-tunnel, while Supermarines would be given Instruction To Proceed with a prototype of the Dagger-engined variant. The Sabre would also have its priority increased, getting resources that otherwise would largely have gone to the Rolls-Royce Griffon. Meanwhile, the order book for the Manchester would be cut back until the Vulture showed some sign of improving reliability. Avro's proposal for a four-Merlin version had already been rejected — with all three of the current four-engined 'heavies' proving troublesome and consuming more than their fair share of industrial capacity, the last thing MAP wanted was another one.
F/Lt Evans sharply banked the Beaufighter to follow the bomber. If it were a Halifax, he thought, he'd have snapped it in his cross-hairs every time, but this Mitchell was more nimble than it looked. As the bomber pulled out of its diving turn, though, its wings were level for just a fraction of a second too long, and Evans' camera clicked. "Gotcha!" he called over the R/T.
"Aw, not again," drawled the Aussie pilot flying the Mitchell. With good humour he added, "There's no shaking you, is there."
Evans grinned. "Ready to call it a day? We'll compare notes on the ground."
"Sure," came the answer.
Some twenty minutes later, having landed at Manston, Evans watched the big bomber coming in to land. By his reckoning, the title of best heavy bomber was a toss-up between the Mitchell and the Stirling, with the Halifax a poor third. The Stirling was at least as manoeuvrable as the Mitchell, but its operational ceiling was lower, and that would put it at greater risk from flak.
Supermarine's bomber was passing its fighter affiliation tests with flying colours; for all the gun camera pictures he'd obtained today, Evans was well aware it wouldn't have been such an easy 'kill' by night.
On discussing the 'combats' with the bomber crew, all agreed that the continued lack of a front turret on the Mitchell was not a serious handicap; a frontal attack was proving difficult even by daylight, while in darkness (Evans reckoned) it would be practically suicidal for the fighter, who would have the choice of colliding with the bomber or missing entirely and getting a packet from the rear-gunner for his pains. Their subsequent report on the day's tests reflected this, recommending that the faired-over nose be standardised for the production version, leaving the four-gun tail turret as the Mitchell's only defensive armament. This was to prove too radical for the Air Ministry, though, who insisted on the addition of a pair of waist guns.
Report from Supermarines to Vickers management, mid-March 1941.
Type 316 & 317 project status
Work on the first pre-production example of the Mitchell B. Mk I is now
well underway, though delayed slightly by the stream of modification
requests stemming from the Service evaluation.
The jigs for the Dagger-engined B. Mk II (Interim) prototype have been laid
out in Shop No. 4, and construction progress is meeting the schedules
projected in last week's report. The Dagger plumbing is giving much less
trouble than the Hercules.
Performance figures of Supermarine Type 317 - Preliminary estimates.
Based on measurements by A&AEE Boscombe Down, extrapolated to full equipment.
Powerplant: 4x Bristol Hercules II of 1,272hp (outer) or 1,164hp (inner)
Maximum speed: 279mph at 14,500ft
Cruise speed (fully laden): 224mph
Radius of action: 1,750mi
Operational ceiling: 25,000ft
Rate of climb: 700ft/min
Payload: 16,000lb of bombs (21,000lb in overload condition)