Vengeance 10

The military officers and civilian officials invited to watch the launching filtered to the far end of the table as the talk became increasingly technical, and the scientific staff gathered about the head. Bethwig thought it strange that Speer, who for all his interest seemed a lightweight in scientific matters, should prefer to indulge in what must have been a boring discussion of velocities, specific impulses, radio telemetry techniques, and a myriad other engineering concerns.

When he finished, Speer turned to Dornberger. ‘I understand, Colonel, that another purpose of today’s launching was to test a guidance system?’

Dornberger nodded and folded his napkin. ‘Our A-Three rocket was cursed with the problem of maintaining directional stability. The rocket would turn on its axis during powered flight, thus making it impossible to keep a proper course. At first we thought this a result of wind acting upon the fins, but wind-tunnel tests disproved that. It was due rather to fluctuations in the exhaust stream. To correct the problem, Wernher developed a gyroscope system that controls the movement of the vanes in the exhaust stream. Now, when the rocket begins to veer, the gyroscopically controlled vanes bring it right back by bending the exhaust in the opposite direction.’

‘I see. Exactly how does the system work?’ Speer asked. Dornberger began to sketch on a napkin. ‘It is really quite similar to a child’s top spinning inside a metal cage. Like a top, it always remains upright, no matter which way the surface on which it is mounted tilts. To take advantage of this natural phenomenon, a metal rod fixed to the rocket is passed through the top’s centre. A series of electrical switches are placed along the rod, and as the rocket begins to veer off course the rod turns with it, thus touching the top and closing a switch, which sends an electrical impulse to the motor controlling the graphite vanes extending into the rocket’s exhaust. The rocket is thus turned back on its proper course.’

‘My congratulations, Herr Doktor.’ Speer rose and bowed to von Braun.

Von Braun laughed and shook his head. ‘Thank you, Herr Speer, but the credit goes to spy work, not to us.’

‘Spy work?’

The others at the table groaned. It was an inside joke that had grown hoary with age but always drew the expected reaction from outsiders.

‘Yes, the system was developed by an American named Robert H. Goddard who developed the first liquid-fuelled rocket in 1923 and is now working with a small grant from the American government somewhere in their western states. Dr Goddard published a paper in 1937 which was ignored by nearly everyone in the world, including the Americans. But one of our embassy employees in Washington obtained a copy from the Library of Congress and sent it on to the Army Weapons Development Centre at Kummersdorf on the chance that it would be of value. Dr Goddard was actually the first to use vanes in the exhaust stream to control flight, and I would say that his work has saved us at least three years. Fortunately for us, his own people have ignored him entirely.’

The rowdier members of the party had begun to stagger off to bed, and the table grew quiet. A soft breeze blew landward, drawing its cooling breath across the parched island. Speer asked a few more questions about technical problems, then leaned back in his chair and regarded Dornberger for a moment.

‘Where will you go from here?’

‘To the A-Four,’ Dornberger replied without hesitation.

‘A-Four? I must admit that I was curious as to what intervened between the old A-Three and today’s A-Five.’

‘The A-Four is a very ambitious step forward and has been our objective all along,’ von Braun told him. ‘We did not realise just how ambitious until we were rather far along in its design. We saw very early that we needed a great deal more information than we possessed or could ever hope to gain from the A-Three. So, we dropped it and designed the A-Five as our test vehicle.’

‘Wait just a moment.’ Speer clutched his head in mock despair. ‘You are making me dizzy with so many numbers. Tell me, just what do you intend the A-Four to do?’

All eyes turned to Colonel Dornberger. ‘It will carry a thousand-kilogram high explosive warhead three hundred kilometres.’

An artillery officer, who had remained, whistled in amazement. ‘What do you intend its accuracy should be?’

‘Plus or minus two kilometres. And,’ Dornberger added, ‘we hope to improve that to within half a kilometre.’

The officer calculated the range in relation to impact deviation on his slide rule and shook his head. ‘Impossible,’ he said flatly.

‘I do not understand the technical details of artillery ballistics,’ Speer murmured, ignoring the officer, ‘but even I can recognise the value of such a weapon. How long would it take to produce one operational by troops under field conditions?’