With a price of one thousand gold royals for each balloon, its price was even higher than that of the steam engine, while its production cost was actually lower. The airbag was mainly a drawn picture by Soraya while the hemp rope and bamboo basket were bargain-priced goods. In fact, Roland had already created a prototype and tested it in the factory courtyard: A hydrogen balloon which could carry Lighting and Maggie simultaneously and ascend into the sky.
After repeated consideration, he finally decided to abandon the idea of a hot air balloon fueled by coal gas. The needed equipment would use up too much space, and the manufacturing process would also be very troublesome. Moreover, Roland would have to import that coal from other cities, which for a small-scale production would be extremely cost-ineffective, far inferior to hydrogen which was so much easier to facilitate.
He coated the test product with a single-sided water coating, which ensured that even after being burned, nothing would happen to the paper. As a result, the whole air sac had hardly any weight while its flexibility was very outstanding. In the experiment, after inflating the balloon, it would fear neither rain, impact, or fire. Maggie even turned into several kinds of birds to throw vicious attacks against the balloon but it was still unable to leave even a small trace. Only by using an iron needle were they able to pierce through the millimeter-thick coating. And since the construction of the air sac was very lithe, a hydrogen balloon with merely a diameter of about two meters was already enough to carry an adult.
The only difficulty laid in how they would solve the gasification problem of the high-pressure hydrogen bottle.
Selling a DC motor for the electrolysis of water was impossible. A motor connected to a steam engine could inflate all hydrogen balloons, which was obviously not that cost-effective. If he wanted a steady flow of gold royals from the hands of the wealthy and powerful merchants, he would have to find a way of create high-pressure bottles which could be refilled repeatedly.
The air bottle itself was not difficult to build. The usage of secondary material could be made up with the wall’s thickness, thus using pig iron and wrought iron was good enough and with Anna personally being the one to manufacture it, processing the bottle accurately also wouldn’t be a problem. The critical point was in the fact that the later generations of air bottles had a pressure level of 20mPa or higher, wishing to reach that by relying on a bicycle pump was undoubtedly nothing but a fantasy, even the help of ten Qilins wouldn’t change this, he at least had to obtain a high-pressure pump. And having a high enough pressure inside the bottle wasn’t enough if there wasn’t a way to fill the hydrogen balloon with it later.
The high-pressure air pump was divided into a piston compressor and a turbine compressor, the former belonged to the internal combustion engine technology tree, while the later fell under the scope of turbine engines. No matter what type he would try to research and develop, they would both be time-consuming and laborious projects. Until late in the afternoon, Roland finally came up with a simple solution: A simple self-inflating bottle.
The inspiration for it came from a news article he had seen before: A street vendor had been selling hydrogen balloons and used a modified liquefied gas tank to store the hydrogen, which in the end resulted in an explosion. The cause of this laid in the problem that the peddler had used diluted sulfuric acid and aluminum to create hydrogen inside of the bottle, but hadn’t correctly calculated the amount of reaction. Which resulted in the issue that the pressure inside the tank had become too large and had broken the bottle.
Thus, the self-inflating method was to pour diluted sulfuric acid and an active metal into the bottle so as to replace the hydrogen. The commonly used metal in laboratories was zinc, while the one used to create most of the hydrogen was aluminum, both materials were not accessible during this era. So Roland still intended to use Lucy’s power to dismantle iron and purify it into high iron. The problem of its slow reaction speed at room temperature could also be improved by using heat and enlarging the contact area (for example using thin iron pieces or iron powder), while an inner coating could resist the corrosion effect of the acid liquid that was inside the bottle.
Thinking until here, he immediately drew a simple sketch on paper. In order to reduce the air leakage, the high-pressure bottle needed to be made as one whole piece, with only a raised threaded hole at the top, which could be screwed into a valve with a gas nozzle.
