Free Vengeance 10 by Joe Poyer

wondered.
    He decided on a straightforward account. ‘The Germans are developing a powerful rocket which will have the capability of flying perhaps three hundred and fifty to four hundred and fifty kilometres,’ he began. ‘It will carry an explosive charge of up to twelve hundred kilograms. The motors for this rocket are being constructed down there.’ Memling pointed to the distant roof of the Manufacture d’Armes.
    ‘In the Royal Gun Factory?’ Paul asked in surprise. ‘A rocket? Like a fireworks rocket?’
    Memling shook his head impatiently. ‘No. Nothing like that at all. This one will be all metal, perhaps thirty metres high, with a powerful motor in which a mixture of petrol or alcohol and liquid oxygen will be burned. It will be able to climb thirty or more kilometres into the stratosphere and continue on for up to four hundred and fifty kilometres.’ Memling became aware that he was speaking much too quickly and drew a breath, fighting to slow himself down.
    ‘If launched from anywhere along the Atlantic or North Sea coasts, it could fall anywhere in London. It could be fired north to devastate Stockholm or across the Mediterranean against Egypt or targets in the Middle East.’
    Paul whistled softly. ‘How do you know all this?’
    The question was logical and at least did not express the complete disbelief he had been expecting. He began to relax a bit. ‘I saw the motors.’
    ‘Just the motors?’
    Memling nodded.
    ‘Tell me where and when.’
    The cloud along the western horizon had broken, and reddish light rushed through to flood the distant hills. Below, the city, shrouded in a century of industrial grime, remained grey and dismal. Memling began by describing his chance meeting in 1938 with Wernher von Braun and Franz Bethwig, his subsequent flight from the train, and the encounter with von Braun three days before, which had led to his glimpse of the sealed area.
    ‘I studied mechanical engineering and was also a member of the British Interplanetary Society,’ he continued, noting that Paul did not smirk or grin at the name as so many others had. ‘Before the war I helped to develop several small rockets that used liquid fuels. I am quite familiar with some of the problems.’
    Paul nodded. ‘I think I understand. Tell me about what you saw at the works.’
    ‘There was sufficient time for me to get a good look. It was a bell-shaped object one and half metres high and half that wide. The bottom flared into a bell muzzle as a rocket nozzle would do. Above the nozzle was a spherical container from which a series of pipes depended. The sphere was most certainly the combustion chamber.’
    ‘How can you be certain of the size?’
    ‘The soldiers were moving another one inside. It was on a standard factory cart which stands exactly thirty-six centimetres high on its wheels. I measured one. The rocket motor rose to the level of the soldier’s chin. When he stood upright, he was as tall as I am, which is one point eight metres exactly.’
    ‘You are very perceptive. Where did you obtain the performance characteristics?’
    Memling cleared his throat. ‘An engineer must be a good observer. As for the specifications ... I - I calculated them from the dimensions of the engine.’
    Paul nodded for him to continue.
    ‘From the apparent diameter’ - Memling’s voice was feverish with the urgent need to make this man understand - ‘of the nozzle it is possible to estimate the width of the rocket. From the diameter of the combustion chamber it is possible to construct a series of estimates of specific thrust based on the fuels that might be employed. Given that, the rate of fuel and oxidiser use can be estimated, which suggests the amount of fuel that can be carried and thus the possible range. That, in turn, provides an estimate of the weight of explosive that can be carried. Military considerations would further limit the choice of weights; for instance, it would make no sense to shoot a