and went down, searching for the spot. She got a lot of static, then the note again-a pure machine-like tone about an octave above middle C. “I think this could be it!” she said joyfully. The wavelength was 2.4 meters. She made a note in the little book Digby had tucked into the suitcase.
Now she had to determine the direction. Incorporated into the receiver was a dial graduated from one to 360 with a needle pointing to the source of the signal. Digby had emphasized that the dial had to be aligned precisely with the center line of the boat. Then the direction of the signal could be calculated from the heading of the boat and the needle on the dial. “Lars!” she called. “What’s our heading?”
“East-southeast,” he said.
“No, exactly.”
“Well. .” Although the weather was fine and the sea was calm, nevertheless the boat was moving all the time, and the compass was never still.
“As best you can,” she said.
“One hundred and twenty degrees.”
The needle on her dial pointed to 340. Adding 120 to that brought the direction around to 100. Hermia made a note. “And what is our position?”
“Wait a minute. When I shot the stars, we were crossing the fifty-sixth parallel.” He looked at the log, checked his wristwatch, and called out their latitude and longitude. Hermia wrote down the numbers, knowing they were only an estimate.
Sten said, “Are you satisfied now? Can we go home?”
“I need another reading so that I can triangulate the source of the broadcast.”
He grunted in disgust and walked away.
Lars winked at her.
She kept the receiver tuned to the note as they motored south. The needle on the direction finder moved imperceptibly. After half an hour she again asked Lars for the boat’s heading.
“Still one-twenty.”
The needle on her dial now pointed to 335. The direction of the signal was therefore 095. She asked him to estimate their position again, and wrote the numbers down.
“Home?” he said.
“Yes. And thank you.”
He turned the wheel.
Hermia was triumphant, but she could not wait to find out where the signal was coming from. She went into the wheelhouse and found a large-scale chart. With Lars’s help she marked the two positions she had noted and drew lines for the bearing of the signal from each position, correcting for True North. The lines intersected off the coast, near the island of Sande.
“My God,” Hermia said. “That’s where my fiance comes from.”
“Sande? I know it-I went to watch the racing car speed trials there a few years back.”
She was jubilant. Her guess had been right and her method had worked. The signal she had been expecting was coming from the most logical place.
Now she needed to send Poul Kirke, or one of his team, to Sande to look around. As soon as she returned to Bletchley she would send a coded message.
A few minutes later, she took another heading. The signal was weak now, but the third line on the map made a triangle with the other two, and the island of Sande lay mainly within that triangle. All the calculations were approximate, but the conclusion seemed clear. The radio signal was coming from the island.
She could hardly wait to tell Digby.
7
Harald thought the Tiger Moth was the most beautiful machine he had ever seen. It looked like a butterfly poised for flight, its upper and lower wings spread wide, its toy-car wheels resting lightly on the grass, it long tail tapering behind. The weather was fine with gentle breezes, and the little aircraft trembled in the wind, as if eager to take off. It had a single engine in the nose driving the big cream-painted propeller. Behind the engine were two open cockpits, one in front of the other.
It was cousin to the dilapidated Hornet Moth he had seen in the ruined monastery at Kirstenslot, and the two aircraft were mechanically similar, except that the Hornet Moth had an enclosed cabin with seats side by side. However, the Hornet Moth had looked sorry for itself, leaning to one side on its broken undercarriage, its fabric torn and oil-stained, its upholstery bursting. By contrast, the Tiger Moth had a sprightly look, with new paint bright on its fuselage and the sun glinting off its windscreen. Its tail rested on the ground and its nose pointed up, as if it were sniffing the air.
“You’ll notice that the wings are flat underneath but curved above,” said Harald’s brother, Arne Olufsen. “When the aircraft is moving, the air traveling over the top of the wing is forced to move faster than the air passing underneath.” He gave the engaging grin that made people forgive him anything. “For reasons I have never understood, this lifts the aircraft off the ground.”
“It creates a pressure difference,” Harald said.
“Indeed,” Arne replied dryly.
The senior class at Jansborg Skole were spending the day at the Army Aviation School at Vodal. They were being shown around by Arne and his friend Poul Kirke. It was a recruiting exercise by the army, who were having trouble persuading bright young men to join a military force that had nothing to do. Heis, with his army background, liked Jansborg to send one or two pupils into the military each year. For the boys, the visit was a welcome break from exam revision.
“The hinged surfaces on the lower wings are called ailerons,” Arne told them. “They are connected by cables to the control column, which is sometimes called the joystick, for reasons you are too young to understand.” He grinned again. “When the stick is moved to the left, the left aileron moves up and the right one down. This causes the aircraft to tilt and turn left. We call it banking.”
Harald was fascinated, but he wanted to get in and fly.
“You’ll observe that the rear half of the tailplane is also hinged,” Arne said. “This is called the elevator, and it points the aircraft up or down. Pull back on the stick and the elevator tilts up, depressing the tail, so that the aircraft climbs.”
Harald noticed that the upright part of the tail also had a flap. “What’s that for?” he asked, pointing at it.
“This is the rudder, controlled by a pair of pedals in the footwell of the cockpit. It works in the same way as the rudder of a boat.”
Mads put in, “Why do you need a rudder? You use the ailerons to change direction.”
“Good point!” Arne said. “Shows that you’re listening. But can’t you figure it out? Why would we need a rudder as well as ailerons to steer the aircraft?”
Harald guessed. “You can’t use the ailerons when you’re on the runway.”
“Because. .?”
“The wings would hit the ground.”
“Correct. We use the rudder while taxiing, when we can’t tilt the wings because they would hit the ground. We also use the rudder in the air, to control unwanted sideways movement of the aircraft, which is called yaw.”
The fifteen boys had toured the air base, sat through a lecture-on opportunities, pay, and training in the army-and had lunch with a group of young pupil pilots. Now they were eager for the individual flying lesson which had been promised to each of them as the climax of the day. Five Tiger Moths were lined up on the grass. Danish military aircraft had been officially grounded since the beginning of the occupation, but there were exceptions. The flying school was allowed to give lessons in gliders, and special permission had been granted for today’s exercise in Tiger Moths. Just in case anyone had the idea of flying a Tiger Moth all the way to Sweden, two Messerschmitt Me-109 fighter aircraft stood on the runway, ready to give chase and shoot down anyone who tried to escape.
