Zeppelin

Zeppelin - By using lighter than air cells and some way of directing motion, team uplift could travel by air, bypassing border patrols. This is a proposal that has been floating around on the thread for ages.

In any case it is a complex project with many components and problems to be solved.

## In-character Reasons

**Notice**: as of Chapter 99, Hazo has realized the implications of hot air rising, recalling his tower jump, while thinking about ways to make border crossing easier.

It is not possible to construct a Zeppelin prototype without first having the required knowledge, inspiration, and desire to do so.

In particular, we can only control Hazo. While other party members could be capable of coming up with ideas and knowledge, it is probably unreliable at best.

Possible paths to this knowledge include:

* Experimentation with implosion seals in a container, especially if the container does not collapse and is lightweight enough.

~~\* Thinking back on sky lanterns(from festivals and celebration) and tower jump. Hot air rises.~~

~~* Hazo felt the hot air updraft from a bakery.~~* ~~Hazo may be able to experiment using the campfire and a square paper box.~~ **COMPLETE**

* Thinking about the nature of a vacuum and how it relates to gas.

* May lead to misconceptions if not properly formulated.

Desire to do so:

* Hazo likes to innovate and create new things
* Supporting survival strategies - no one else would have flight(except sand), well out of reach.
* Mention of sand gliders
* Supporting merchant empire - much easier to transport cargo
* Hidden heaven becomes much easier to reach and supply

Facilitating his ability to come up with new ideas are the books that he has bought, such as the book on math, architecture, material engineering, and woodworking, but sadly there is no physics book among them. He should also be keeping a commonplace notebook where he could keep his observation on natures and write down ideas he might have.

## Roadmap

Engineering a Zeppelin will not be done quickly, and in any case, some theoretical development and leap of logic must be done first.

Below is a series of steps that will lead Hazo and his team to developing the zeppelin for long distance aerial travel.

There two means of lift we could investigate, ideally with the vacuum lift first, as it offers the greatest lifting ratio.

### Vacuum Lift

A plausible reason for doing this is simple curiosity to see what would happen to a vacuum if there is no air to rush toward it.

To discover vacuum lift, it is necessary to use a lightweight object, such as a balloon, and seal, Strengthening Seal for this to work.

Using an implosion seal left inside an airtight balloon, and a strengthening seal to ensure that the structural integrity doesn't collapse, it should yield a balloon that float.

### Hot air

Hazou could replicate a sky lantern by making a paper lantern with a fire at the bottom of it. It should be a relatively small fire so it doesn't burn the wooden frame.

If it's necessary to generate heat by fire on the fly in a zeppelin, it should be easy to store charcoal in storage seals and burn it when the time come.

Creating charcoal should be easy enough for the team, though deforestation would be noticeable.

Of course, any seals that generate some sort of heat will be a welcome development, especially if they are more efficient than charcoal.

### Determination of Weight-to-Lift ratio

Regardless of the methods of lift we chosen, we need to estimate how much materials we need to lift a certain amount of mass, from their perspective, independent of whatever math or physics we performed.

The team could simply build balloons of predefined size, and inflate them, and then make enough until everyone go up.

### Aerodynamic

Hazou could construct small scale prototypes of the balloon, or craft paper planes to learn aerodynamic.

To test aerodynamic concept in a more controlled environment, a wind tunnel could be constructed using some sort of techniques to generate wind, such as Wind Wall, or a propeller powered by counterweights.

This should allow him to obtain the knowledge to create lift and control surfaces. If no source of thrust can be found, knowledge of aerodynamic and how they work will be enough to navigate, even if it will be slow.

### Source of Thrust

Hazo already knew Kagome's use of explosive seals to chop woods, and knew that it create some sort of force that push people and things apart from the explosion.

Using woods and explosive tags, he could observe the propulsion of a surface. From there, it should be easy to construct a thrust engine using a wooden enclosure.

## Sealing Tech Tree

This is a list of seals that we have already developed, or need to develop. They arranged in a tree structure, listed from already developed seals to undeveloped seals, usually in order of development needed to be done. Red links marked a seal that is not yet available or developed.

Some part of the tech tree will represent alternate paths to the development of the Zeppelin, while other are purely complementary.

* Five-Seal Barrier - A seal that lock an object relative to earth while giving it massive damage resistance.

* Strengthening Seal - A mobile version of the five-seal barrier without the lock, used to strengthen materials. Most likely to be weaker than the five-seal barrier. It is likely a necessity in creating a vacuum lift balloon, though it may not be for a hot air balloon.

* Explosive Seal

* Shaped Charge Seal - A seal that provides unidirectional force.

* Impulse Seal - A reusable and non-destructive version that should be able to provide propulsion for the zeppelin.

* Heat Seal - A seal that increases the temperature of the surrounding area. This is speculatively placed as an explosive seal variant, as such a seal might get its explosive power from increasing temperature. This seal design would cut out all effects of the seal except the temperature increase. It is probably reusable, but it may not be. If it isn't, then the next design would be a reusable heat seal. This seal would be used to create hot air, which is one of the two methods of lift.

* Implosion Seal - A seal that stores all air in a certain radius, creating a vacuum. Tends to become damaged and explode due to air rushing to fill the void. The seal would be used to create a vacuum balloon, provided that its shape does not collapse.

* Storage Seal - In its current form and without further development, it has a ready and wide variety of uses. It could be used to store a modular zeppelin, store counterweights, as well materials and supplies to make sure the Zeppelin is light enough for travel.

* Tunneler's Friend - Aside from helping team uplift operate in higher altitude, it could also store hot air, serving as an alternative method to the heat seal or similar. That required a method of heating air in advance(such as a campfire) before storing it for use. It will also be essential to inflating any envelope to full size for locking into place.

* Higher Capacity Tunneler's Friend We may need higher capacity to store more hot air.

* Higher Capacity Storage Seal - By expanding the volume and mass we can store, we can build larger modular components, speeding up setup.

* Barrier\_Method\_Formation\_(lesser) - Chakra tripwire needed for activating seals, usually only one seal on each end.

## Techniques

* Transformation (Henge) - By transforming into blankets, the team could use themselves as materials for the zeppelin. This should only be used as a last resort if we couldn't find any source of airtight materials to make our zeppelin with.
* Elemental Clone - By using clones, the team don't have to suspend themselves above the fire as blankets.

## Physical Construction Plans

There are a few ways we could make a zeppelin, with a variety of required seals. The simplest, is to just make a seal which makes a material virtually indestructible or immobile relative to itself without fixing it to the reference frame of the earth. This would be a variant of the 5 Seal Barrier that Kagome currently knows. For the following paragraphs, the variant will be referred to as Strengthening Seal or SS.

### **Lift:**

Lift is achieved by having the total weight of the Zeppelin with any cargo be less than the weight of the air it displaces.

If we assume we need to be able to bring four times the weight of team uplift, this means we need ~1000 kg of lift, which means the ship must displace ~1000 m^3 of air. So, we could have a single spherical balloon with a radius of 6 meters. For safety's sake, we should probably throw in a second.

* **The Vacuum Method:**  We need some form of airtight container which we can apply SS to to secure a rigid form such as the stomach of a giant whale. Once it is formed, we need to place an implosion seal inside it, which we can activate based on a timer, or from outside. After applying SS, have the implosion seal go off. Now we have lift.

* **The Hot Air Method:**  As an alternative to using a vacuum to achieve lift, we could instead create a seal akin to Akane's Elemental Mastery technique. The technique already creates a sphere of hot air around the user, so suspending a seal (or a cluster for longer flights) in the middle of a balloon or bladder should not be too difficult.

To counterbalance it so that we don't just fly away, we can just seal and unseal weights from storage seals. This lets us move up and down.

For the sake of safety, the maximum altitude should be limited to ~3000 meters, until cabin pressurization and/or air scrubbing is available. Otherwise, occupants are at risk of altitude sickness.

Any forms of Lift need to be modular and preferably re-inflateable mid-flight. Partitioning portions of the lift section will give us a greater chance to survive a hole being blown through our Zeppelin's most vulnerable area. Ideally, we should also have emergency balloons on standby just in case we need to replace the lift generated by a non-repairable damaged partition. This is, of course, a secondary concern to actually creating a working prototype.

### **Assembly:**

Leaving a Zeppelin unattended for other people to see and/or possibly steal is unacceptable. Therefore, our design has to have some assembly required before each launch so that we can carry the necessary materials in storage scrolls as we travel on foot. The canvas for the Zeppeling can simply be folded up and stored in a box in a scroll to prevent the forces of the storage scroll from ripping the material(s). For the undercarriage, we will need to use some type of plank-interlocking system by building off of our characters' experience creating the seal watch tower for the Arikdad mission. Ideally, we will have a modified 5 Seal Barrier seal that will allow us to lock our materials in place without them becoming imobile. We may need a special component to designate as the "center" for these seals since the original work references the center of the planet in order to function.

The Zeppelin is primarily intended to be a long range form of transportation; it is not a get-away vehicle. Initial assembly time (starting from taking out all of the materials from their storage scrolls and ending when the Zeppelin is ready to launch) should take no longer than one hour, but this is not a hard requirement. The same goes for dis-assembly; the faster the better. Once we have a working model we can focus more on optimizing this portion of the project. For our first test runs if for some reason we must use a Zeppelin prototype to travel we will most likely be forced to destroy it upon landing just so it does not fall into enemy hands.

One more issue to keep in mind is that all seals have an expiration date. If we try to remain airborne for too long and we do not have a way to reapply seals mid-flight we will be in deep trouble. Version 1.0 needs to have enough redundancies in its lift system to prevent catastrophic failure, where such failure involves all of our characters plummeting to their doom. So long as we remain airborne and can reach whatever might break we can salvage the situation.

### **Thrust:**

We have various options for thrusts, including an option not to use any engines at all.

**Ballasts and Horizontal Wings:**

The basic idea is that you'll achieve some equilibrium altitude with a given amount of lift. Basically the point at which you stop being lighter than the air around you. At this point, you unseal something heavy, which will make you quickly lose altitude.

You have fins or wings on the sides of your craft. If it's feasible, you can angle the wings downward at 45 degrees. Otherwise you can tilt the entire craft by having more weight on the nose-end (using more storage seal unsealing). As you lose altitude, the pressure of the air pushing on your wings will translate some amount of your vertical velocity into horizontal velocity.

At some point (assuming you don't want to hit the ground) you seal the heavy weight. Your vertical velocity will go to zero as drag and lift slows you down, then you will rise back up to the initial altitude. At this point, you angle your wings again (or the entire craft).

**Impulse Engine:**

We have explosive seals which break Newton's third law. We can use them for thrust. Simply create a secured off room and apply SS liberally. Then, point the explosive seal in the direction we want to go, and set it off. This gives us bursts of thrust equal to the force exerted by the explosive seal.

An impulse seal is a variant of a shaped charge that activates non-destructively, preferably continuously, providing force in the one direction.

In the longer term, a more typical Zeppelin shape would increase the efficiency. Placing the 'engine' in the nose of the vessel in front of the center of mass would give motive force, while control surfaces on the outside could steer the ship.

**Pressure Engine:**

Another way to use our violations of Newton's third law is to capitalize on the fact Kagome has recoilless seals which resist pressure without themselves being pushed. Rather than using an impulse seal, use the idea that these seals don't transfer pressure from one side of the seal to the other.

This allows setting up a pressurized container where the force downwards is cancelled out, resulting in a net force in the direction of the seal. Only the side without the seal will be affected by the increased pressure, which means there will be a net thrust away from the seal. This lasts as long as the seal is in its recoil-negating state.

In this design the seal is not providing impulse directly; the impulse is instead provided by the pressurized air in the container.

**Jet Engine**:

Use a faster release variant of Tunneler's Friend seal. Store up air as reaction mass. Then release the inside an enclosed box. Finally, open a trap door that is built into the enclosed box, to let the air down.

**Human-powered Propeller**:

An alternative method of propulsion would be human-powered propellers. This would required a deeper understand of how gearing works, but could be done with Kagome's woodworking skills.

### **Steering:**

There are three main methods to steer the airship. One is to use two side-mounted propulsion systems, allowing the craft to turn when one side is shut off or reversed. Depending on how this is accomplished, this may be slow. A variation on this is to use RCS, or reaction control systems, to steer. This would work by having outward facing propulsion systems mounted either fore or aft of the center, and pulse them to turn the craft. The third way would be with aerodynamic control surfaces, like the rudders or elevators that are seen on real world aerospace vehicles.

## Countermeasures and Solutions

* **How do we avoid getting spotted?** - The easiest solution is to simply to avoid traveling by day, and to navigate only by night. Note that navigation by night over ground is significantly different than navigating on the ground, and there is a strong possibility of getting lost. On the other hand, traveling in the air gives a greater range of sight, and if there is knowledge of constellations, traveling by the stars is fairly easy. Another solution is to use camouflaged materials in construction, making the craft difficult to see, as well as flying high enough to avoid observers on the ground. It may be possible to use the Macerator Seal to help create clouds, although it could look unnatural or out of place, or simply unable to create enough clouds to hide in. Alternatively, the zeppelin could simply fly fast enough to outrun any ninja, making getting spotted less of a problem. Naturally, different methods of hiding would be combined. Night flying might use primarily dark color as camouflage, while still flying high and fast.
* **What about charka beasts?** - We already have means of dealing with opponents at range. Mori Keiko in particular is our weapon specialist who can accurately throw kunai at distance, or explosive tag or the macerator. We could work on dedicated weapon emplacement, such as a ballista or a seal derived weapon, but it isn't strictly necessary.
* **How would we get down without lowering the Zeppelin or in an emergency?** - Roping down a really long rope is one option, but that's only usable when the Zeppelin isn't in danger. An emergency option is to freefall for some time, before henging into really large blankets. Alternatively, with the impulse seal, we could use retrorocket propulsion to slow our descent down. Finally, we could develop parachutes, which would be a more effective version than our blankets. The key to survival is to develop redundancies, with both our Zeppelin and our options for getting down safely, and never assume they will work without extensive testing.
* **How would we test the zeppelin in secret?** - Keep the zeppelin hidden by keeping it low until it's out in the middle of ocean, and then raise altitude. Or do it under the cover of darkness. To minimize danger from being spotted, it would be best to delay testing the zeppelin as much as possible, close to the day the team would pack up camp, but not too much to allow for thorough testing. Alternatively, it would be possible to test the invention in the summon realm with a team of Pangolin, preferably deep inside the clan's territory.

## Useful Information

Standard Atmospheric Data

Link to TV Tropes information page on Airships: http://tvtropes.org/pmwiki/pmwiki.php/UsefulNotes/Airships

1. ↑ 1959 ARDC Model Atmosphere compiled by the USAF
2. ↑ Oxygen content information pulled from higherpeak.com/altitudechart.html