Vengeance 10

Von Braun interrupted, banging his empty stein on the table and shouting for the barman. ‘Please, please. No politics. Politics give me a headache. I do not care where the money comes from so long as I am allowed to build bigger and better rockets. Then one day soon, God willing, we will travel to the moon and beyond.’ Memling instantly forgot his uneasiness. A warm sense of companionship sped through him, and when the barman had departed, he drank off the second stein in one long gulp. They were three young men who shared a dream, and that was all they needed to understand one another.

‘Wernher and I were about to celebrate a very successful day,’ Bethwig told him. ‘We are intent upon the finest supper and the best bottle of hock this hotel can supply. Will you join us?’ Memling did not think to hesitate.

* * *

‘… And so, after we poured the liquid oxygen into the tank through a funnel, just as we used to in the old days at the Raketenflugplatz, we ducked behind the logs that formed our shelter and waited three minutes for the vapour pressure to build. Franz ran out and opened the fuel mix valve. You should have seen him trying to scramble back up the slope in that rain.’ Von Braun was roaring with laughter and had to wipe his streaming eye’s. Bethwig was laughing even harder, and Memling could not remember having such a good time since the Paris congress.

‘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 scep-ticism, 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.’