1636 The China Venture – Snippet 34
Island of Jinmen (Quemoy), in Liaoluo Bay, near Xianmen (Amoy)
“Set it down over here, please,” Jim Saluzzo ordered.
The sailors carried the crate over to the designated place. “Here, sir?”
“Yes, thank you,” said Jim.
There were three crates in all, holding all the parts of their hot air balloon. One held the envelope itself. When inflated, it would be fifty feet in diameter, seventy feet high, and hold almost seventy thousand cubic feet of hot air. The envelope was carefully pulled out of its crate and laid on a wheeled pallet.
For the purpose of the balloon inflation and launch, Zheng Zhilong had secured an old building, somewhat rundown, but with a large unadorned courtyard. On one wall there was a large double gate.
The balloon envelope was carefully laid out on the courtyard and the sailmaker from the Rode Draak and his assistant carefully checked it, gore by gore and inch by inch, for tears and mildew. It was late morning and the light was good for this purpose. The envelope was patched as needed, then just as carefully folded up, laid on a padded rolling pallet, and rolled into the protective cover of the inwardly extended roof of the northern building.
They also checked the rigging. Cables would be used to attach the basket to the load frame and the load frame to the moth of the balloon envelope, and three ropes, anchored in an equilateral configuration, would be used to tether the balloon so it wouldn’t wander around the countryside. Thanks to Zheng Zhilong, they had been able to replace their hemp rope with silk rope, which had a higher tensile strength per unit length.
Another team of sailors reassembled the basket, under the direction of the ship’s carpenter. It had a pinewood base and sides made of rattan and willow woven together.
In the meantime, Jim and Mike were looking at the burners. There were four burners, all told. Two would be mounted on the load frame; two were spares. They were light enough to be lifted with one hand, although it was far more comfortable to use two.
In Montgolfier’s late eighteenth century hot air balloon, the passengers had stood in an annular gallery surrounding the gaping mouth of the envelope, and had tossed flammable materials through a port onto a grating that covered that mouth. These materials caught fire and heated the air, which rose into the interior of the envelope. It was not, however, an efficient way of heating the air.
Modern hot air balloons use propane burners. The propane is compressed to liquefy it and when released became a gas once more.
Propane came from natural gas. However, while the Chinese did make use of natural gas in Szechwan province as a fuel for boiling brine, those natural gas wells were hundreds of miles away. And anyway, the Chinese hadn’t tried separating propane out from the other gases, let alone liquefying propane.
So if the hot air balloonists from Grantville didn’t want to be limited by how many tanks of propane they took to China, they needed to burn a different sort of fuel. And so some experimenters had modified the propane burner design so it could burn a less volatile fuel, like kerosene or even diesel oil, under pressure. Animal and vegetable oils could be used in place of diesel oil, with a bit of tweaking of the atomization system.
“Okay, all four burners are working, let’s head off to bed,” said Jim.
It was perhaps an hour before sunrise. Jim was out first, and was pleased to note that while there was a bit of wind–smoke was drifting to the northeast–the leaves on the trees weren’t moving. So, Beaufort Scale One, 1-3 mph. Of course, Jim didn’t have the benefit of a true weather forecast, but the clouds were few and unthreatening, and the barometer appeared to be holding steady. That was a nice surprise, as it seemed to rain every other day in Xiamen in June.
Jim was captain of the ground crew; Mike was to be the pilot. And his passenger was to be their patron, Zheng Zhilong.
The chosen launch site was a large field on Jinmen Island, some yards from the dwelling that they were using as a base of operations. Jinmen Island was dumbbell-shaped, on nearly an east-west axis. The cove in which Zheng Zhilong had defeated the Dutch in October 1633 faced south. The launch field was on the southwest arm of the island, with a coastal ridge sheltering the balloon from the southwest monsoon. The city of Jiamen lay to the west, about fifteen miles away. Xiamen itself lay on the west coast of another island, and a smaller island lay between Jinmen and Xiamen.
Jim, Mike and the ground crew put together the basket, secured the uprights, and attached the load frame. Then they mounted the burner on top.
“Burner test, everyone back,” said Jim. There was a rush of blue flame. Some of the spectators jumped back, even though they weren’t in harm’s way. Jim turned off the fuel valve and the flame petered out.
“Okay, it works. Let’s lie it down.” Mike and the others came over and gently laid the basket over on its side. The crew attached the envelope to the basket, and streamered it out, directly away from the top of the basket. Four lines ran from the basket to heavy anchors–cannon barrels. One was the short tie-off, which the pilot would release when he was ready to launch. The others were the three tethers. Since they didn’t want the balloon to make a free flight and perhaps create a disturbance, they would remain fastened until the balloon was safely deflated. They had several lengths of tethers at their disposal, which were over four hundred feet long. Since the tethers would be running up at a 45 degree angle, the balloon couldn’t rise higher than about three hundred feet, and Jim didn’t intend to go above two hundred feet.
Two sailors grabbed the lines attached to the mouth of the balloon envelope with gloved hands and held the mouth open. Two more held onto the crown line, that is, the line attached to the top of the envelope. The purpose of the crown line was to steady the balloon if there was a wind, or if the balloon started rolling or otherwise misbehaving.
Jim and Mike placed the blower to one side of the basket, aimed at the mouth of the balloon, and with the engine’s exhaust pipe pointing away from the basket.
Jim started it up, and watched the little ribbons attached to the skirt of the mouth. Some were blown in by the fan, others blown out by escaping air.
“Um, too close.” He shut down the fan and slid it a few inches further away. He started the fan up again, and this time all the ribbons were blown in. And the grass to the side of the mouth was not moving.
“Just right,” Jim commented. He switched the fan back on, put a foot on the base, and held the top rail with both hands.
“That is one of the propellers you have told me about?” asked Zheng Zhilong. He had to shout the question.
Jim nodded. “It is, but this one is designed to move air, not water.”
Gradually, the balloon filled with air. It was cold air, of course. As it filled, Mike walked around, making his pre-flight check. It would, after all, be his life on the line. The sailmaker walked with him, making his own inspection, and at the last removed the ribbons.
Mike gave Jim a football “T for timeout” signal. It meant that cold inflation was just about complete.
“Mike, you are in command,” said Jim, and he reduced the blower to half throttle.