The Dam Busters

^{CHAPTER V} OVER THE HURDLES

HUMPHRIES, the new adjutant, arrived next afternoon; a little fair-haired man, only twenty-eight, he was keen on flying but his eyes had stopped him. Gibson told Humphries as much as he knew himself, and as Humphries was leaving his office Gibson said:

“I don’t know yet what it’s all about, but I gather this squadron will either make history or be wiped out.”

In the morning the curtain lifted a little. Gibson got a call from Satterly, who told him to catch a certain train to Wey-bridge, where he would be met at the station.

“May I know who I’m meeting, sir?”

“He’ll know you,” Satterly said.

Gibson walked out of Weybridge Station at half-past two and a big man squeezed behind the wheel of a tiny Fiat said, “Hello, Guy!”

“Mutt,” Gibson said, surprised. “Are you the man I’m looking for?”

“If you’re the man I’m waiting for, I am,” Summers said. “Jump in.” They drove down the winding tree-lined road that leads to Vickers and went past the main gates without turning in. “What’s this all about, Mutt?” Gibson said, unable to hold back any longer.

“You’ll find out.” He turned off up a side road to the left. “You wanted to be a test pilot for me once. D’you remember? “

“I remember.” That was when he had first met Summers. It must have been eight years ago now, back in 1935, when he was eighteen. He had wanted to fly, so he had got an introduction to Summers at Vickers and asked about becoming a Vickers test pilot. “Go and join the Air Force and learn to fly first.” Summers had advised.

“You’ll be doing some testing soon,” Summers said. “Not for me exactly, but quite a test.” He turned in some double gates and they pulled up outside the house at Burhill. Summers led the way into a room with windows looking over the golf course, and a white-haired man got up from a desk.

“I’m glad you’ve come,” Wallis said. “Now we can get down to it. There isn’t a great deal of time left. I don’t suppose you know much about the weapon?”

“Weapon?” Gibson said. “I don’t know anything about anything.”

Wallis blinked. “Don’t you even know the target?”

“Not the faintest idea.”

“My dear boy,” Wallis said in a sighing and faintly horrified voice. “My dear boy.” He wandered over to the window and looked out, pondering. “That makes it very awkward. This is dreadfully secret and I can’t tell anyone whose name isn’t on this list.” He waved a bit of paper in Gibson’s direction and Gibson could see there were only about half a dozen names on it.

Summers said, “This is silly.”

“I know,” Wallis said gloomily. “Well, my dear boy… I’ll tell you as much as I dare and hope the A.O.C. will tell you the rest when you get back.” Gibson waited curiously, and finally Wallis went on: “There are certain objects in enemy territory which are very big and quite vital to his war effort. They’re so big that ordinary bombs won’t hurt them, but I got an idea for a special type of big bomb.”

He told Gibson about the shock waves and his weird idea for dropping bombs exactly in the right spot. Gibson was looking baffled trying to follow the shock wave theory.

“You’ve seen it working in pubs, Guy,” Summers said. “A dozen times. The shove-ha’penny board. Remember how you get two or three discs lying touching and flick another one in behind them. The shock waves go right through them but they all stay where they are except the front one, and that goes skidding off. That’s the shock wave.”

“Come and I’ll show you.,” Wallis said and led Gibson into a tiny projection room. Wallis thumbed the switches and a flickering screen lit up with the title “Most Secret Trial No. 1.” A Wellington dived into view over water and what looked like a big black ball fell from it, seemed to drop slowly and then was hidden in spray as it hit. Gibson started in amazement as out of the spray the black ball shot, bounced a hundred yards, bounced again in a cloud of spray and went on bouncing for what seemed an incredibly long time before it vanished. He was still staring at the screen when the lights went up again.

“Well, that’s my secret bomb,” Wallis said. “That’s how we… how you’re going to put it in the right place.”

“Over water?” Gibson said, fishing for a clue.

“Yes,” but Wallis avoided the subject of the target. “Over water at night or in the early morning when it’s very flat, and maybe there will be fog. Now, can you fly to the limits I want, a speed of two hundred and forty miles per hour, at sixty feet over smooth water, and be able to bomb accurately?”

“It’s terribly hard to judge your height over water,” Gibson said, “particularly smooth water. How much margin of error is allowed?”

“None. That’s the catch. Sixty feet. Just that. No more. No less. So the aiming will be accurate.”

“Well… we can try. I suppose we can find a way.”

“There’s so much to do.” Wallis sighed.

On the way back to Scampton, Gibson puzzled over the target. The only likely ones, he decided, were either the Tirpitz or the U-boat pens, and he shuddered a little at the thought of a low-level attack on them. They would be smothered in guns. At Scanipton he found some Lancasters had arrived and ground crews were checking them over. In the morning he told his senior men what height they would have to bomb at but nothing about the bomb itself.

Dinghy Young said: “We’ll have to do all the training we can by moonlight, and you don’t get much reliable moonlight in this country.”

“Could we fly around with dark glasses on?” Maudslay asked.

“No, that’s no good. You can’t see your instruments properly.”

Gibson said he’d heard of a new type of synthetic night training. They put transparent amber screens round the per-spex and the pilot wore blue glasses; it was like looking out on moonlight but you could still see your instruments. He would see if Satterly could get them some.

Leggo was worried about navigation. Low-flying navigation is different. You don’t see much of the area when you’re low, so they were going to need large-scale maps with plenty of detail. Large-scale maps meant constant changing and awkward unfolding. He suggested they use strip maps wound on rollers; navigators could prepare their own. And if they were flying low, radio was not going to be much use for navigation. It would be mostly map reading.

Bill Astell, deputy A Flight commander, took off the first Lancaster and was away five hours, coming back with photographs of lakes all over the north country. Gibson laid out ten separate routes for the crews to practise over, and in the days that followed the Lancasters were nosing thunderously into the air all day and cruising at 100 feet over the flat fens of Lincolnshire, Suffolk and Norfolk.

Flying low seems faster and is more exciting, also more dangerous. There is the temptation to slip between chimneys or lift a wingtip just over a tree, and the R.A.F. was losing a lot of aircraft every month from fatal low-flying accidents. It was (naturally) strictly forbidden, and the pilots were delighted to be ordered to do it. Across several counties outraged service police reached for notebooks and took the big AJ aircraft letters as they roared over their heads; the complaints came flooding into Gibson’s office, and with smug rectitude he tore them up.

After a few days they came down to 50 feet and flew longer routes, stretching out to the north country, threading through the valleys of the Pennines, climbing and diving over the Welsh mountains, then down to Cornwall and up to Scotland, eventually as far as the Hebrides, winging low over the white horses while the pilots flew steady courses and the rest of the crews gave a hand with the map reading.

Gibson took his own Lancaster, G for George, and flew over a lake in the Pennines, to test the business of flying accurately at 60 feet over water. Diving over the hills he flattened out over the lake, then pulled up over the hills at the far end; tried it several times and found it fairly easy to keep his altimeter needle steady around 60 feet. But the trial meant little. Over Germany barometric pressures would be unpredictable, and altimeters work off barometric pressure. He had to find some way of judging his height without relying much on the altimeter. Practice might do it.

He tried again at dusk with fog drifting over the lake, and it was different. Not pleasantly. The smooth water merged with the gloom and he found he did not have much idea about judging height. They very nearly went into the lake and as he pulled sharply up there was a grunt over the intercom as Trevor-Roper in the rear turret saw the ripples on the water from their slipstream. Even Spam Spafford, Gibson’s chunky bomb aimer, was shaken. He had had a disconcerting vision of the looming water from the nose perspex.

Gibson flew back and told Cochrane that if he could not find some way of judging height accurately there would be no chance of doing the raid.

“There’s still time to worry about that,” Cochrane said. “Just now I want you to have a look at models of your targets.” He waved a hand at three packing cases in a corner of his office and Gibson eyed them curiously. “You can’t train your men properly unless you know what they are, so I’m letting you know now, but you’ll be the only man in the squadron to know. Keep it that way.”

A corporal brought in a hammer, and Cochrane sent him out of the room while Gibson gently prised the lids loose and lifted the battens. He stood looking down at the models, and his first reaction was a feeling of tremendous relief. Thank God, it wasn’t the Tirpitz! It took him a couple of seconds after that to realise they were dams. One was the Moehne, and the other two the Eder and the Sorpe, handsome models that showed not only the dams but the countryside in detail for miles around, as though photographs had taken on a third dimension. There were the flat surfaces of the lakes, the hills, winding rivers and the mosaic of fields and hedges. And in the middle the dams. Gibson stood looking for a long time and then Cochrane laid the lids back over them.

“Now you’ve seen what you’ve got to attack,” he said. “Go and see Wallis again and come and see me when you get back.”

The first thing Wallis said, eagerly, was:

“How did you get on?”

“All right by day,” Gibson said, “but not so good at night. In fact, flying level at night over water at sixty feet seems pretty nearly impossible.”

“We’ll work out some way of doing it. Now I’ll tell you more about this Downwood business.”

“Downwood?”

“The code name for the raid.” Wallis explained how the bombs were to explode deep against the dam walls.

“I’ve calculated that the first one ought at least to crack them, and then more bombs in the same place should shift the cracked wall back till it topples over… helped, of course, by the water pressure. The best times, of course, are when the dams are full. That will be in May. You’ll need moonlight, and there’s a full moon from the thirteenth to the nineteenth of May.”

“Only about six weeks.”

“Yes.”

“Oh,” Gibson said and went back thoughtfully to Scampton.

The synthetic night-flying gear arrived, transparent amber screens and blue glasses; “two-stage amber,” it was called.

The screens were fitted in the cockpits, pilots donned then-glasses arid flying by day was exactly like flying in moonlight, they flew thousands of miles with them, first at 150 feet and then, as Gibson decided they were good enough, at 50 feet, the bomb aimers looking through the nose to warn of trees and hills.

Gibson took the screens and blue lenses away and sent the crews on low-level night cross-countries, first aircraft singly, and then, when the moon was right, in loose formations. Two crews were too keen and came back with branches and leaves in their radiators.

Gibson was on the move from dawn to midnight every day, usually careering about on a little auto-bike from flights to armoury, to orderly room and so on. When he flew he kept his auto-bike in the hangar, apparently against some fiddling regulation because Scampton’s zealous service policeman told Chiefy Powell the auto-bike would have to be moved.

Powell eyed him flintily. “You’d better see the owner,” he said. “I don’t think he’ll move it.”

“I’ll see him all right,” said the sergeant, “and he’ll move it too.”

So Chiefy took him in to see Gibson and shut the door behind him. There was a violent roaring behind the door and a white-faced sergeant came out.

The bike stayed where it was.

The crews practised low-level bombing on the range at Wain-fleet, diving over the sand dropping n|-lb. practice bombs with the low-level bombsight. The drops were not nearly accurate enough and Bob Hay said so disgustedly. Gibson took the problem to Cochrane.

Two days later a Wing Commander Dann, from the Ministry of Aircraft Production, called on Gibson.

“I hear you’re having bombsight trouble for the dams raid.”

“How do you know about this?” Gibson said.

“I’ve been let into it because I’m supposed to be a sighting expert,” Dann explained. “I think I can solve your troubles. You may have noticed there are a couple of towers on top of each dam wall. We’ve measured them from the air and they’re six hundred feet apart. Now this&”—and he produced some drawings of a very elementary gadget—”is how we do it.”

It was laughably simple; a carpenter ran up one of the gadgets in five minutes out of bits of spare wood. The base was a small triangle of plywood with a peephole at one angle and two nails stuck in the other corners. “You look through the peephole,” Dann said, “and when the two towers on the dams are in line with the nails, you press the button. You’ll find it’ll drop in the right spot but you’ll have to stick right on the speed.”

Gibson shook his head in wonder. Workmen put two dummy towers on the dam across the neck of a midland lake, the bomb aimers knocked up their own sights and on his first try one of them dropped eight practice bombs with an average error of only 4 yards.

Still the problem of the height. Gibson tried repeatedly to see if practice made perfect, but it didn’t. After his fifth try Dinghy Young landed and said, “It’s no use. I can’t see how we’re going to do it. Why can’t we use radio altimeters ? “

Gibson said he had thought of them a long time ago but they were not sensitive enough.

Time was getting short. Gibson got a call from Satterly. “They’ve finished the first two prototypes of the new bomb.” Satterly said. “Fly down to Herne Bay tomorrow and watch the test drops. Take your bombing leader with you.” That was April 15.

Wallis met them and next morning they drove out to a bare beach near Reculver. Half a mile back from the sea M.I.5 had cordoned the area off.

“I’m sorry to get you up so early,” said the ever-courteous Wallis, “but the tide is up and that is the right time. We want to walk out at low tide and see how the bomb stands up to the shock of dropping.”

In the east came two specks which grew into Lancasters, heading low over the shallows towards two white buoys bobbing on the water. “The other one’s the camera aircraft,” Wallis said as they watched them, and as the noise of engines filled the air Wallis was shouting above the roar, “He’s high. He’s too high.” He sounded agitated. They swept up side by side and a great black thing dropped slowly away under the nearer one. It hit and vanished in a sheet of spray that hissed up towards the plane. For a moment there was nothing but the spray, and then out of it the fragments came flying.

“Broken,” Wallis said and stood there very still. He took a deep breath. “They said it wouldn’t work. Too big and heavy and the case too light. We’ve got another in the hangars. We’ll try it this afternoon. The aircraft was too high.”

Men worked hard that afternoon to strengthen the case of the second bomb while Wallis stripped to his underpants and waded to his neck in the freezing water, feeling with his feet for the fragments of the broken one. A launch took the broken bits on board and Wallis climbed in shivering, oblivious of everything but the ragged edges where the metal had burst.

They were on the dunes again as the sun was going down and the two aircraft came in sight, lower this time. Mutt Summers in the bomb plane was holding her steady at 50 feet. The suspense was painful. The black monster dropped away below, and again the water gushed skywards as it hit and out of the foaming cloud came the flying fragments as it broke.

Wallis said “Oh, my God! “And then out of the spray the jagged bulk of the main body of the bomb lurched into the air and skipped erratically for a hundred yards or so before it rolled under the water. Wallis stared in silence for a few seconds with the look of a man who has lost a shilling and found threepence. He sighed, and said, “Well, it’s a bit better than this morning.”

(In the Lancaster, Summers was not happy. A lump of the casing had hit the elevators and one of them had jammed. The plane could just hold its height while Summers was holding his breath. He did a wide gentle turn and made a heart-stopping landing on the long runway at Manston with the trimmers.)

Wallis told Gibson: “We’ve still got a lot of work to do on the bomb j but don’t worry, it’s going to be all right.” Gibson and Hay took off in a little plane for Scampton and a few hundred feet up the engine coughed and died. There was only one way to go and that was down, but all the good fields were still covered with poles so the Germans could not land troops in an invasion. Gibson did his best to steer between them but a wingtip hit a pole, and as the aircraft slewed the other wing hit and they finished up sitting in a ball of crumpled duralumin, but were able to climb out.

A man came haring across the field, and when he saw they were not badly hurt he said severely, “I think they teach you young fellows to fly too early” and then a policeman arrived and said unemotionally, “I’m glad to see our landing devices work.”

Gibson and Hay went back to Scampton by train, and on the way Gibson thought up a scheme to overcome the height problem: to dangle a long wire under the aircraft with a weight on it so it would skim the water when the aircraft was exactly at 60 feet. Full of hope, he tried it in G for George, but it didn’t work. At speed the line trailed out almost straight behind.

Cochrane set the “back-room boys” to work on the problem and a day later Ben Lockspeiser, of the Ministry of Aircraft Production, arrived at Grantham with an idea. It was absurd to think how simple it was—and how effective. “Put a spotlight under the nose,” he said, “and another one under the belly, both pointing down and inwards so they converge at sixty feet. When the two spots come together on the water, there you are! “

Maudslay flew a Lancaster down to Farnborough and they fitted two spotlights on it the same day. Coming back he made test runs across the aerodrome and it worked beautifully. Maudslay said it was easy to get the circles of light together and keep them there. The idea was that they should touch each other, forming a figure “8.” He had Urquhart, his navigator, leaning his head out of the perspex observation blister behind the pilot, looking down at the ground and saying, “Down, down, down… up a bit… O.K.,” and that was the procedure they adopted. They all tried it over Derwent Water using the same drill, and could fly to within 2 feet with wonderful consistency. Everyone was pleased but not exactly in ecstasy, because the same thought was in all their minds. An aircraft pelting up to a defended target at 60 feet did not make the crew very good insurance risks. And when it was showing lights too…

Down at Weybridge Wallis was still trying to strengthen the bomb and things were not going well. On April 22 they flew the first new model over to Reculver and dropped it; it didn’t break up, but the case crushed on Impact once more and, after two erratic hops, the bomb went straight to the bottom. The tormented Wallis had a pretty problem now. There was no time to re-design the casing. Three weeks to the date for the raid and if they couldn’t make the time it would have to be put off for another year; probably, in view of official scepticism, for ever. The water in the dams was rising. In the next week Wallis got little sleep while he spent long hours working to find little ways of making the casing just that much stronger. He was living on hope.

On April 29 they finished another modified bomb and Vickers test pilot Shorty Longbottom flew it to Reculver for the drop. It was pouring with rain and Wallis, out on the dunes, did not even notice it as he eyed the Lancaster diving out of the east towards the markers. Longbottom had her tucked down neatly to 60 feet at 258 indicated air speed, squinting through the rain squalls to hold his height and see the markers. The bomb fell slowly, and then out of the usual shower of spray it came bounding in majestic and perfect flight—and went on bouncing for half-a-mile. Down on the dunes, Longbottom, banking round, saw a white dot bobbing about. Wallis had taken his hat off and was waving it in the air, dancing and shouting while the rain ran down his face.