The Thruster Pack:
The school term had now come to an end and Harry and Hermione had opted to write examinations together. Hermione as a year six primary school student wrote the exams at the expected time with the rest of her classmates. Harry was specifically accommodated as a gifted student. Of course, Harry had 'tailored' the situation to his liking. Harry and Hermione had both applied to the Ministry of Education to be home-schooled instead of attending Secondary school. The local district officer was naturally curious as to how such brilliant children had popped up at St. Grogory's Primary – a known troublemaker hotspot.
When the woman had arrived at the school to see the students with her own eyes, merely out of curiosity, it did not take Harry long to 'convince' the woman that he and Hermione Granger were better off starting the GCSE syllabus immediately. Harry had instructed the woman, under his compulsion to make the necessary arrangements where nobody would ask any questions. Harry was quite aware that this was not ethical, but he could see no alternative. Harry and Hermione were going to take the standard core GCSE Subjects at double the suggested workload with private tutors. This would simultaneously be accompanied by high-intensity magical studies.
Grace in her continuous flying missions had encountered a problem. There was a barrier that she could not fly across it without getting violently sick. Grace had arrived one evening, with some of her feathers missing and she had spent at least half-hour coughing before she vomited. Harry had never been very scared and he hugged Grace closely and prayed as the foreign magic passed through her system. However, not everything had gone badly. Harry rechecked the upgraded GPS collar that he had bought, and realised that he could see when Grace had immediately turned back sharply.
"Your job after you get better is to fly close to the same spot. You will not go far into whatever made you sick. As soon as you feel something you turn back and apparate immediately. We are going to plot points around whatever this thing is. I think you are on to Azkaban. For the next week, no more flying. Stay in and rest, okay?"
"Eeeeeppppp"
"Good Girl. Proud of you. Don't think I haven't noticed you are doing 200kph. That is race car fast."
Grace had given Harry a slow blink as she accepted the comment.
Hermione had suggested that after establishing Azkaban's location, it would be optimal to involve Sirius in the breakout plan. Perhaps Sirius had not attempted to escape because the Dementors were suppressing his Animagi abilities. Harry concluded that he would also need a device to physically break the cell. If the cell was part of an outer wall, explosives were a possibility. If they were doing an infiltration, something to cut the cell bars would be necessary. However, this sequence of events depended on some other missing components. He would not be able to carry out the jailbreak by himself.
He would need Remus Lupin.
He would also need after establishing the location, to fly to Azkaban. Brooms seemed to be a good option, but he had a nagging suspicion that if it was easy, somebody would have already done it. If Azkaban magic could get Grace severely sick, he would need to test if brooms possibly malfunctioned.
And finally, the last resort in his toolkit – he would have to master the Patronus charm.
Harry had been casting the spell for a while now and he had managed to conjure a white silvery shield. From the reading he had done, this would keep the dementor at bay but not necessarily kill them. The Patronus charm essentially drove the Dementors away quite effectively, but it had never managed to kill a dementor. Harry had still not managed to summon a happy memory. Most of his memories felt dominated by contentment, determination, or curiosity. The issue seemed to be that seventeen months of a happy time were not to rub off seven years of pain.
Harry considered if he should merely drive the Dementors away during the rescue. After looking through recollections from the last war in his parent's journals, he changed his mind. Harry was taking no chances.
The only good dementor was a dead Dementor.
If he could develop a way to kill them, in the future Lord Moldypants would have no access to them. That according to Lilly Potter's journal, would only leave the Giants. The Giants could be dealt with easily, by using the same weapon.
He would have to deal with the personnel at Azkaban. Lorna had been digging and it seemed that there always was a small contingent of Aurors stationed there. He decided that he would have to stun them, and a magical gun that could fire stupefy spells in rapid succession would deal with the issue easily. Sufficient target practice was mandatory and perhaps the guns could be manufactured first. That way he could get ample practice time.
Central to the armour systems, apart from the shielding was to integrate communication technology. Maybe even Hermione could keep an eye out for him during the mission, with a drone? Harry while he muttered to himself, wrote the checklist down as the thoughts came to his mind, only to be stopped by Hermione as she had been looking through the new broom creation spells that Lilly had invented.
"I am aware you are considering a broom, but I think building a jetpack from scratch is a better idea. I have an idea why the brooms fail in Azkaban actually," commented Hermione.
"Do tell?"
"Right so, we have something in Mastery level charms called the stabilisation energy matrix. If a person could just apply random spells to an object infinitely, surely you could build whatever you wanted without consequence."
"I think I understand where this is going. There is a limit, Mione?"
"Correct. It depends on how magically heavy the spell is. Generally, singular objects can take several trivial spells or two main heavy spells. The spells in the Charms syllabus are not arranged according to difficulty or usefulness, but according to magical weight."
"So, there is a method to the madness then. Interesting. So wait, how do brooms work? They seem to have several heavy spells?"
"Before I answer that, the most important thing is that sometimes you can stretch the limit of how many spells a singular object can take. However, the energy to cast every successive spell becomes far higher. Failure to provide the energy results in magical explosions. Deadly magical explosions."
"Oh dear, now I understand why only Artificers undertake this type of work."
"Exactly. Even worse is that if an object that has been stabilised with multiple charms is hit with a powerful enough combat charm, warding scheme or enchantment, it can destabilise the 'binding matrix' and also cause a magical explosion. By the way, am not talking about weak first-year spells, I am talking about a fair amount of power being delivered here."
"So, the Azkaban voodoo magic that gets Grace sick could kill a broom mid-air in flight?"
"Only if an object has multiple heavy spells on it. Now naturally your mum Lilly, found a very muggle workaround. By the way, it is so brilliant, I don't even think I could ever be that clever."
"What did she do?" Harry asked
"Well Harry to answer your question, brooms generally use runes. However, remember the patchwork-quilt problem? The runic arrays may work, but they guessed a lot to get it to that state. It works well enough, but nobody knows why.
Your mum went the engineering route and designed spells that could be applied to separate pieces of the broom. Then they would be mechanically assembled with standard carpentry techniques. It would allow for spare parts to be produced, and for each part to merely be mechanically connected. No 'binding matrix' necessary."
"You are telling me my mum solved a complex esoteric Charms problem by using nuts, bolts and wood glue?"
"Yep. As for my original statement….
I think a jetpack will serve you better. You see with a jetpack, you could vertically jump or land on your feet, scale a wall and do many other acrobatic things. No need to travel with a broom and you can work these things into your fighting. Brooms require at least one hand. Imagine the jetpack is controlled by your back and you can use both hands to hold a rifle? The charms seem experimental, but they are your mother's personally created spells. I am confident that her stuff is solid. I am hoping you might give the materials an upgrade, twigs are so yesterday."
"You have me sold. Jetpack it is. Too bad for the brooms. Good for quidditch, but I have no time to chase snitches, bitches."
It was at this point that Lilly gave James a consoling pat on his back as she said, "Sorry husband, he might have your genetics for flying but he is in the big leagues now."
"Ah damn. Well, let us see what they will do…." James replied.
"Anyway, Harry I am going to scoot home, I feel tired. I know you will get up to mischief. Keep me in the loop?"
"No problem. I will take your advice and look at the brooms. See you later."
A half hour later after eating a turkey sandwich, Harry took out the last untouched Cleansweep and began to examine it. He activated his mage sight and then looked for runic arrays. He found nothing until he saw a little sliver of magic floating from a certain part of the handle. After scraping off a cleverly hidden layer of paint, Harry was surprised when he was met with metal hex bolts. After using his 5mm Allen key, Harry was even more surprised when he lifted an entire panel from the handle and the runes were now exposed.
So even magical manufacturers were beginning to use standard nut and bolt hardware? This was utterly perplexing until it hit him – Wizards would be too stupid to take it apart as they had no mechanical inclination. Harry then had a full belly laugh for the next five minutes, before resuming the examination of the device.
Harry who was fairly accomplished at Runes himself had a look and saw a classic case of the patchwork-quilt problem. The main featherweight charm was surrounded by other runes that seemed to act as constraints. They were not close enough to affect the function of the main array but close enough to force the magical energy not to spill out randomly into the environment. It seemed to be a common technique. Priya had a scheme that was similar to this, and it had allowed her to store and emulate many medical spells in her Medi-Bracelet.
As he analysed the runic array, he realised that this broom would be a nightmare to mass produce. There seemed to be an absolute mixture of runes. Elder futhark mixed with Sanskrit and Hanzi? No wonder these brooms were expensive and manufactured in small volumes. Somehow, they had jury-rigged the thing until it would be stable. People often flew on these brooms reliably. Perhaps they had searched out all the runic scripts in the world and then made a dictionary of actionable words that could be used as a toolkit.
"A runic programming language, how interesting?" he thought to himself.
The issue was that there was some logic in certain places and in other places, just intuition. He did want to scratch build his solution, as he didn't have the time to take everything apart or study it. Now he had to weigh his options. His mother's notes had everything needed to turn a normal broom into a flying broomstick – the issue was that new spell creation was dangerous. They could easily be the first of their kind.
Harry decided to use his mother's broom spells, but he would modify the twigs as he wondered how surface area played into the ability of the charm to accelerate air.
The first step was to eliminate the efficiency of using inconsistent twigs. He needed surface area and a lot of it. He also wanted everything ducted not exposed to the air. What had a lot of surface area and was available to him? He thought about it for a little while and then he realised that at the microscopic level, coal was very porous and he had some from a recent barbecue. Now he would build a small rough prototype and observe the characteristics.
He inserted some coal into a piece of 38mm pipe and fell into a short trance as he transfigured the separate pieces into a single structure. He then drilled out a central tunnel with a long drill bit and fell into a short trance again, as he reinforced most of the coal body into a network of carbon nanotubes to prevent the material from degrading. The inner surface of the tunnel had been left with a lattice structure that would hold the material intact, but allow air to diffuse through. After catching his breath, Harry had then applied his mother's custom air acceleration charm. When he held the device in his hand and dripped magic into it, the air velocity was almost comparable to a jet of compressed air.
Worst case scenario, he now had a free handheld air compressor tool. Not bad, at all!
Harry decided to compare the produced thrust of his "pipe compressor" to broom twigs from the Cleansweep to get some baselines. When he calculated the mass, based on his scrapped broom parts, the rough estimation was that the entire twig assembly on a Cleansweep broom produced approximately 72 kilograms of thrust. For equal weights, the twigs did not possess even half of the thrust of the enhanced coal structure.
So how did a paltry 72 kilograms of thrust lift a fat ass wizard? Harry reasoned that the featherweight charm on the broom handle was offsetting the rider's weight. His goal was to produce enough thrust where that would not be necessary. He began to wonder what materials he could use, from around the house. Invictus who had been sleeping to preserve his memory awoke to find Harry performing the hustle and bustle as usual.
"Hello grandson, what are we up to?"
"Hi Gramps, I would like to think I have found a material that can replace broom twigs. Remember the broom company mum wanted to start? Been looking at the spells. So far, my very informal measurements indicate for the same weight we are looking at twice the amount of thrust. I am going to make a bigger test piece now."
"Oh – exciting. Minimise me let me get a first-person view?"
"Done!" Harry said as he minimised the portrait and placed Invictus around his neck.
Harry left the null-box and returned with a nondescript metal pipe and began to replicate the same design. The only difference was twelve air tunnels, and they were somewhat cone-shaped to assist with 'ramming' the air into the 'thruster.' This second prototype was approximately the same size as the twig assembly, and Harry was anxious to see how it performed. Now it was time to charm the item.
"Velocitas Tempestas" he muttered.
As Harry applied the spell, a rather alarming amount of magic seeped out of his wand as it seemed to diffuse throughout the whole structure. He could see the magic slowly branch out as his Mage sight was active. The pattern looked different from the Cleansweep – the magic in the Cleansweep assembly seemed stronger on the outer twigs and most of the twigs in the central part of the assembly had little to no magic at all. His assembly was much more consistent. Consistent dense magic was present on the twelve 'Ramjet' tunnels he had created.
"Well grandson, let us see what we have here?" Invictus asked.
Harry grabbed an assortment of supercapacitors from his stash including a single B.M.P and left the room with his 'thruster'. As he arrived at his shed, he wheeled out his industrial scale that he had purchased for weighing graphite slabs. He switched it on, and he placed the thruster assembly on it as he began to drip magic into the assembly by touching the coal-graphene complex with his smallest capacitor. The thruster created enough force to generate at least 150kg of thrust before the smallest powercell died out. That was almost double the amount of thrust created by the Cleansweep. That was more than enough to lift him. But only three seconds of run time?
"Well?" asked Invictus.
"Better performance requires far more energy. So I can understand how the magical energy storage of plain objects probably stopped the performance of magical items. We are getting 150 kilograms. That is enough to lift me. Easily. But three seconds of run time?"
"Maybe it needs more juice? Dump more power into it?" Invictus suggested.
Harry decided to jump directly to the B.M.P. just as a joke. That was when the madness set in, and the tree above him began to rustle with the thrust. He could only run the device for 20 seconds before neighbours would complain. But the thrust….
Four hundred kilograms.
That was enough to lift him eight times over. Harry considered that the massive permeability and the surface area along with large amounts of magical power were making the trust. Suddenly Harry began to smile. There was one material that was even more permeable and had an even more ridiculous surface area.
Aerogel.
There was enough thrust, so Harry decided to scrap the afterburner. It was far more important to develop magical power regulation and reliable thrust control systems. Harry decided that he would move everything to Peverell Manor eventually so that he could have more space to work. Harry called it a successful evening and could not wait for Hermione to show up tomorrow. It was time to work on getting Remus on board and designing the weapons.