‘Anyway’ – von Braun pushed himself up, hiccupped, and gulped another mouthful of wine – ‘he… he threw himself over the barrier just as the fuse burned down – can you imagine? we forgot to bring a fuse with us; I had to go all the way to the army base at Cassel to borrow some – and the rocket lit off with a bang.’
‘It sounded like a cannon,’ Bethwig chortled.
‘I was certain,’ von Braun went on, ‘the explosion had destroyed the motor, but when the smoke cleared away, there it was, working perfectly. The flame was almost four metres long and already settling down into a clear, white torch in which you could see the most beautiful diamond shock waves, one right after another. It was truly a wonderful sight. If only we had known this morning that you were here, Jan, we would have taken you along with us.’
Bethwig leaned forward and tapped the table with his bread knife. ‘And do you know, Jan, that engine ran perfectly for a good four minutes and might have done so longer if we had not run out of liquid oxygen. All our previous motors in that series burned through in three minutes!’
With careful concentration, Memling succeeded in setting his wine down without spilling it. ‘I do not believe it!’ He enunciated each word carefully. ‘Pardon my scepticism, gentlemen. But four- four minutes with liquid oxy – oxygen’ – he grinned in triumph – ‘and alcohol is imposs – imposs – can not be done. Our best engine burned up in two.’
‘Ah.’ Von Braun leaned closer and lowered his voice. ‘But now we know how. When the motor cooled, Jan, we took it back to the machine shop and cut it in half. Not even a discolor – discoloration in the area of the throat.’ He smacked the table with his hand and flipped up the empty bread plate. Bethwig caught it, and as he tried to bow, the waiter moved in swiftly and cleared away the rest of the dishes.
Memling made a rude noise, and Bethwig laughed.
‘’S true, damn it.’ Von Braun had lapsed back in German. ‘Franz has designed a new combustion chamber.’ He leered at Memling and pushed his glass away. ‘He drilled small holes in the walls leading to the throat area. The fuel… fuel is pumped down to the combustion chamber… pardon me… pumped down to the combustion chamber where a little bit is bled off and sprayed through the little holes.’
Memling’s face wrinkled in an effort to visualise what his friend was saying. Bethwig impatiently sketched the design on a napkin. ‘See, here. The fuel comes through the side and cools the combustion chamber walls by absorbing heat here, about the throat, where it always burns through. The extra fuel also adds to the combustion process and… and raises chamber pressures.’ He paused dramatically, but the effect was spoiled when he fell off his chair.
‘And the best part, Jan’ – von Braun took up the story, ignoring his friend’s struggles to regain his seat – ‘is that the motor was machined entirely of brass! If Franz’s new cooling system works that well in a material with such a low melting point, then we should have no trouble at all with a rocket motor made of steel!’
Memling’s face glowed as he listened to von Braun’s recital of the day’s events. Bethwig’s new cooling technique was sure to revolutionise rocket motor design; it was as big a technological step forward as change from powder to liquid fuels forecast by Tsiolkovskii and Oberth.
‘The main concern of all rocket experimenters, whether British, American, German, French, or Russian,’ von Braun went on, ‘is to cool the combustion chamber so that the flaming gases at 2900 degrees centigrade do not destroy it.’
Memling shook Bethwig’s hand so vigorously that he upset the wine carafe, which von Braun just rescued with a well-timed catch.
‘My God, I believe you may have given us the future, Franz. Imagine what can be done now! Huge motors utilising your cooling technique to power cargo and passenger rockets across the oceans, into space, even to the moon. Why, we could build a landing aerodrome – no, no, that’s wrong – not an aerodrome but a lunardrome, on the moon. My God, think of it! A matter of a few years. Why, if we all worked together—’
Memling stopped abruptly as political realities overcame his enthusiasm.
‘Jan’ – von Braun had sobered quickly – ‘you must understand that what we have discussed here must never be spoken of again.’ He glanced around the room and bit his lip.
In an attempt to salvage the mood of the evening, Bethwig poured each of them another glass of wine. ‘Mem-ling’ – he pronounced each syllable. ‘It is not an English name?’
‘No.’ Jan hesitated a moment. Von Braun’s warning had troubled him, causing him to remember the real reason for his trip to Germany. ‘My grandfather emigrated from Belgium. He was a gunsmith.’
Bethwig nodded and asked a few more questions concerning his background, the type of questions new acquaintances ask, more out of politeness than any real interest. But the spectre of political considerations stayed with them, and shortly the party broke up. Von Braun and Bethwig were leaving early to begin the drive back to Berlin, and Memling had morning train connections to make to Ostende and the cross-channel steamer. The excuses served admirably.
Had he seen the man hiding behind the newspaper the previous evening in the hotel dining-room? Did they know he was an agent of MI6, or was it just a coincidence they were on the same train?
Memling looked at the old steel watch that had belonged to his father. The Belgian border was just a few minutes away. Customs and passport control had been accomplished at Aachen where he had boarded the train, so there would be no reason to stop this side of the border. Yet….
He shook his own paper and folded it to a new page. The movement caused the man at the window to glance the length of the carriage. So they were watching him! Memling shifted the newspaper until he could just see over the top. The two Gestapo agents exchanged quick glances, and Memling was certain he saw one nod to the other.
The fear that coursed through him was so intense, so unexpected, that he thought he would vomit. In all the training sessions he had endured, there had never been anything so overpowering as this. He found he could not catch his breath, and an ugly blackness was threatening to overwhelm him. He had only one thought, to leave the train as quickly as possible. That nod could only have meant his arrest before the frontier. As if to endorse his terror, the train began to slow.
The carriage was crowded; students returning from Christmas holiday filled the aisle. He had studied the maps carefully, as he had been taught, and knew that they would cross the frontier deep in the Ardennes forest, a relatively uninhabited area with few roads. The driver would not dare stop on a slope this steep with the tracks certain to be icy. At the crest, then, or in the valley on the far side. Ten minutes, five minutes? Who was waiting? Political police, civil police, or soldiers. Mounted or afoot?
Memling wasted no more time in useless speculation. The only thing that might save him was the unexpected. He lowered his paper and stood up casually as if going to the lavatory. Excusing himself, he stepped over the legs of a fellow passenger and pushed his way along the crowded aisle. He knew without turning that at least one of the Gestapo agents was following. As he approached the end of the compartment Memling risked a glance behind and saw that the thin-faced agent had also pushed his way to the aisle. Desperate to force a way through the crowd, he began to use his elbows. He stumbled through to the draughty platform and shoved a young girl away from the door. Someone yelled at him, tried to grab his arm, but he flung the hand off and yanked up on the handle. It refused to move, and he threw his weight on to it, cursing. He yanked a third time and the handle gave way. Memling lost his balance as the door swung outwards, and was sprawled in a snowbank before he realised what had happened. The train rushed by, and pushing himself up, he saw the Gestapo agent leaning far out of the doorway, shaking his fist in frustration. Scrambling up the side of the cut into the icy wind, he stumbled into the forest.