When he saw Anna, Roland was unable to stop the corner of his mouth from raising, every time he saw her his mood would always become a lot better.
The so-called “gift” was covered in a layer of linen and placed in the castle courtyard to ensure Anna’s surprise. He had gotten this idea when he had seen how Ashbringer had covered her sword. Since he was the Prince, the gift of course also had to be something special. Presenting something like jewelry or other similar finished products showed off much less sincerity, so he had to think for a long time before he came up with an idea.
When Roland pulled away the linen, a basket weaved with rattan appeared before them, to which the end of many ropes had been tied with the other sides and connected by a vast canvas.
“This is… what?” Anna walked closer and begun to circle around it full of curiosity.
“A hot air balloon,” Roland replied with a smile, “It can take you up into the sky, overlooking the earth like a bird in the sky.”
“Flying up to the heaven?” She turned around, her eyes flashing with excitement, “Can it really do that?”
Soaring into the sky has been the dream of mankind since ancient times, from a hang glider to a hot air balloon, from the airship to the aircraft, for the exploration and challenge of this, humanity has already paid a huge price, but mankind has never given up on its pursuit. Even though witches have always existed in this word, flying was still only a right for the minority. The scenery from up high was bound to leave a deep impression in someone.
“Of course, you just have to fill the airbag at the end of the ropes with hot air.”
Roland had arranged for Nightingale, Lightning, and Maggie to work as emergency personnel. In the case of an accident, with the help of Lightning together and Maggie in her large sea eagle form, the two of them would be able to land safely. As for the other witches, he decided to temporarily not inform them of this, especially Wendy and Scrolls, they would certainly have opposed any of his adventures. In their eyes, he should absolutely never come even close to even the slightest mishap.
The principle of a hot-air balloon was very simple. To produce it one only had to make their way through a few difficulties, the first part was the burning device, and the second was the airbag.
The first point, in the absence of pressure vessels that could provide gas fuel, he had to rely on firewood or charcoal to heat the air. However, the efficiency of this was too low and he had to come to accept that he wouldn’t be able to fly with it very far with it.
This also meant that the principle of hot air balloon travel had been discovered much earlier than in Roland’s original world, but nevertheless, there was a reason why they had only been able to use it in real combat after the development of hydrogen balloons came along. Roland however, could abandon the burning device altogether, and instead let Anna take over for the heating.
The second problem was to make the airbags airtight, but regarding this issue, it was something that Roland could at least use the experience of his predecessors for, and easily solve the problem by using a sandwiched fabric. The outer layer of the balloon was made out of a wear-resistant canvas, the center layer was made out of the intestinal epithelium of cows, and the inner layer was made out of a light gauze. With this, he was able to prevent leakage, while it also meant that he would not have to be afraid of it being pecked at by birds.
Roland propped up the opening at the bottom of the air sac, allowing Anna to raise the inside temperature with the help of her common flame. It started to slowly begin to bulge up, seemingly to be like a melted wax gourd. By taking into account that the hot air balloon would have to carry two people, the maximum diameter of the balloon needed to be at least at five meters, using up the intestinal epithelium of twelve cows, and its sewing lasted almost for a whole week. If it wasn’t for the fact that he was the Lord of the town, it would never have been possible for him to make such a big toy.
“Does it fly by using the buoyancy provided from hot air?” Anna asked. “I remember that hot air will always rise up.
“Yes, hot air rises, while cold air sinks, this is a common natural phenomenon. Using the particle theory to explain it, due to the air being hot, the particle’s movement will be intensified, increasing its diffusion into the surrounding, and with the expansion of the volume, its density will become smaller. While the density of the surrounding air doesn’t change, the air in the balloon becomes lighter in comparison, causing it to rise.
