Procedural Airships development thread

[skykooler]

I wonder if this would still work if you just slowed to a stop manually; otherwise you'd only be able to make bases within a few hundred meters of the ground for the KAS winches to reach. It would be really neat to eventually make cloud cities on Eve.

[BigFatStupidHead]

I wonder if this would still work if you just slowed to a stop manually; otherwise you'd only be able to make bases within a few hundred meters of the ground for the KAS winches to reach. It would be really neat to eventually make cloud cities on Eve.

Well, Hooligan made cloud cities on Jool using edited KAS winches. Also, It is very slow and annoying to stop manually. Minute drifting is (was?) enough to not be considered stationary.

Edited January 8, 2015 by BigFatStupidHead

[AngelLestat]

I really love what this mod try to acomplish, but each time that I play it, all the mechanism and some physsics seems very far from reality.

I have some understading on pressure, density, buoyancy, airships mechanism and different technologies and how all this can be applied with the ideal gases equations.

Maybe I am wrong or I dont understand what you try to accomplish.

I was trying to see the source code, but all that logic and variables behind make it harded to understand all the steps that you take.

But let me point what is more annoying for me:

The pressure control mechanism.

First I dont understand where the source gas is comming when you inflate or where it goes when you deflate.

Also the speed of how fast is filled goes beyond any practical gameplay or reality.

Second, the pressure limit.. we can see a value of 0.000x (not sure in what units) which if it just vary a little.. we explode.

Those changes are not so drastic in reality, it may be when you get speed, but I guess you simulate that very good, but for sure does not happen due a 2 seconds of fill or few meters on altitude.

Vents: Why it explodes when you vent too much? Why explode due high pressure when you are in fact venting sometimes?

If your internal pressure rise, then it will vent faster, and it will do (at higher rate) until your pressure find equilibrium with the outside.. So is impossible to explode due pressure if you have an automatic valve that opens when the pressure is too high.

The ballast part is fun if we wanna experience old airship technology. But it could have a variable bouyancy technology as submarines or the new aeroscraft.

And it will add more reality to your source of gases.

For example:

If you joint to Community Resource Pack, and you add new code to your plugin, then:

You can use any tank as source of your lifting gas. if is half fill, then you can inflate your airship or compress the gas inside the tank, we can use and extra part to allow this using the fuel ducts and electrical power to compress.

In case we use real fuels, it may calculate with precision the liquid tank volume. This same tank may be used as fuel or for a fuel cell plus electrolysis with universal storage mod.

Right now when somebody install this, if they dont use the default airship, they only see a thing exploding all the time in the pad for no apparent reason. And they quit before even ask.

I cant help you with code.. But I can help you with the math and logic system.

Edited January 25, 2015 by AngelLestat

[FreeThinker]

I heard that NASA has actual real plans to go to Venus with inflatable airships. This means inflatable Airships on alien world is not just a fantasy, but ca very real possibility. I hope inflating will get implemented in the near future so we can see for ourselves how it could work

[ahappydude]

Well, Hooligan made cloud cities on Jool using edited KAS winches. Also, It is very slow and annoying to stop manually. Minute drifting is (was?) enough to not be considered stationary.

Yeah it was crazy how fun you had wityh his plugins. Speceficilly combining the savestate and the squid legs adn you could use to make any part you liked more or less magnetic. You could add that module to an kas part and the kerbals got stuck to the ceilings or floors in space hahah it was a blast

[RadarManFromTheMoon]

I really love what this mod try to acomplish, but each time that I play it, all the mechanism and some physsics seems very far from reality.

I have some understading on pressure, density, buoyancy, airships mechanism and different technologies and how all this can be applied with the ideal gases equations.

Maybe I am wrong or I dont understand what you try to accomplish.

I was trying to see the source code, but all that logic and variables behind make it harded to understand all the steps that you take.

But let me point what is more annoying for me:

The pressure control mechanism.

First I dont understand where the source gas is comming when you inflate or where it goes when you deflate.

Also the speed of how fast is filled goes beyond any practical gameplay or reality.

Second, the pressure limit.. we can see a value of 0.000x (not sure in what units) which if it just vary a little.. we explode.

Those changes are not so drastic in reality, it may be when you get speed, but I guess you simulate that very good, but for sure does not happen due a 2 seconds of fill or few meters on altitude.

Vents: Why it explodes when you vent too much? Why explode due high pressure when you are in fact venting sometimes?

If your internal pressure rise, then it will vent faster, and it will do (at higher rate) until your pressure find equilibrium with the outside.. So is impossible to explode due pressure if you have an automatic valve that opens when the pressure is too high.

The ballast part is fun if we wanna experience old airship technology. But it could have a variable bouyancy technology as submarines or the new aeroscraft.

And it will add more reality to your source of gases.

For example:

If you joint to Community Resource Pack, and you add new code to your plugin, then:

You can use any tank as source of your lifting gas. if is half fill, then you can inflate your airship or compress the gas inside the tank, we can use and extra part to allow this using the fuel ducts and electrical power to compress.

In case we use real fuels, it may calculate with precision the liquid tank volume. This same tank may be used as fuel or for a fuel cell plus electrolysis with universal storage mod.

Right now when somebody install this, if they dont use the default airship, they only see a thing exploding all the time in the pad for no apparent reason. And they quit before even ask.

I cant help you with code.. But I can help you with the math and logic system.

At the moment, PA very much relies on ballonets, which are basically balloons filled with air inside the envelopes. So when you are inflating your ballonet you are basically drawing surrounding air into the envelope (and by doing so increase pressure/reduce static lift). So what you typically what to do is start with inflated ballonets and deflate them gradually while climbing in order to give the lifting gas more room to expand. Withing a distinct pressure margin you can also use the ballonets to influence buoyancy.

However, after all your critique is very valid and I'm already working on an more or less complete overhaul to adress these problems. Here is a little insight on what I'm planning:

PA, in its current form, actually mixes up some concepts. Ballonets, for example, are actually more common on non-rigid, than on rigid airships. Thats also where the "explode on venting" problem comes from. PA just checks the relative pressure of the ballonet and, if it exceeds a distinct margin, causes an explosion. That actually wouldnt happen in a rigid airship since the gas-"bag" could "shrink" inside the ballonet after venting gas.

So to make everything more realistic and interesting I'm planning to introduce "modular envelopes". The idea is basically a lot like modular fuel tanks/real fuels. An envelope has a volume and the player can then add modules and choose how much of that volume these modules should take. This would make it possible to add fuel/lifting gas/ballast etc. tanks into the envelope or to use ballonets or pressurized envelopes like the aeroscraft uses it.

One more thing: I'm actually not an expert on airships. I see PA very much as a way to learn more about them and how they work. If there are airship "enthusiasts" out there who wanna help and/or can provide detailed information/literature tips on the subject, that would be very much appreciated.

[AngelLestat]

So what you typically what to do is start with inflated ballonets and deflate them gradually while climbing in order to give the lifting gas more room to expand. Withing a distinct pressure margin you can also use the ballonets to influence buoyancy.

The theory is fine, but I think that the management system, building and limits can be improved.

I have nothing yet to recomend, let me think about it.

PA, in its current form, actually mixes up some concepts. Ballonets, for example, are actually more common on non-rigid, than on rigid airships. Thats also where the "explode on venting" problem comes from. PA just checks the relative pressure of the ballonet and, if it exceeds a distinct margin, causes an explosion. That actually wouldnt happen in a rigid airship since the gas-"bag" could "shrink" inside the ballonet after venting gas.

what happens if the ballonet is 100% deflated and you still rise altitude and speed?

In that case it would not explode, becouse it only takes into account the ballonet pressure, or I miss something?

Or maybe it takes into account some way the pressure applied on the ballonet from the main envelope and the external pressure?

So to make everything more realistic and interesting I'm planning to introduce "modular envelopes". The idea is basically a lot like modular fuel tanks/real fuels. An envelope has a volume and the player can then add modules and choose how much of that volume these modules should take. This would make it possible to add fuel/lifting gas/ballast etc. tanks into the envelope or to use ballonets or pressurized envelopes like the aeroscraft uses it.

Sounds perfect, I look forward to this.

But not sure if you can use the exactly same code. Unless you ignore pressure and temperature.

One more thing: I'm actually not an expert on airships. I see PA very much as a way to learn more about them and how they work. If there are airship "enthusiasts" out there who wanna help and/or can provide detailed information/literature tips on the subject, that would be very much appreciated.

I am one of them, I never travel in one, but I love them.

Recently I am studying the Havoc Mission Concept to see if it can be improve it.

About the Aeroscraft, it use some kind of ballonets and pressure light envelope as tanks.

I will explain in details how it works just in case you miss something:

(1) Helium Pressure Envelopes (HPE): These are the envelope tanks where the hellium is compressed, an electrical pump takes hellium from the (2) main envelope into (1) HPE. This generates a vaccum over the (2) main envelope which draw external air into the (3) ballonets.

The reverse process release the compressed hellium from HPE to the main envelope, the same electrical pumps that were used to compress are now used as generators to recover the energy wasted in the compression with a 80% efficiency, this force the ballonets to push the air outside.

Now, take into account that this image represent only the prototype which does not have a real payload.

In the real case the ballonets (more of them) would expand over all the remaining volume of the main envelope, the HPE volume is always the same, the only that changes is pressure.

All this is not enoght to reach 3650 meters, so here enters another design aspect.

The shape of the aeroscrafts is like a wing, it generate lift which increase altitud -> so drag decrease -> speed increase -> lift increase -> until it reach 3650 meters at full payload.

Hellium can be partially compressed to equal pressure with the outside air due venturi effect at 222 km/h - 120 knots (max speed)

The ballonets are always open with the exterior air, there is no valves or control mechanism. (not sure, but is a guess)

Then we have the third tech improment:

The Landing Cushions: This is pointless for the mod, but the system is great and I like to share it.

-They deploy or retract in fly using the same electric pumps from HPE to improve aerodynamic on fly.

-They aid landing on unimproved surfaces, even water, and perform like a hovercraft during taxi by pushing air through them. In addition, the landing cushions are equipped with very powerful gripping/suction capabilities that ensure the vehicle stays grounded and in place when not in flight.

http://www.spacepatents.com/patented_inventions/pat8864068.pdf

This mod can work as landing gears for airships:

http://forum.kerbalspaceprogram.com/threads/83134

Inside we have a diesel electrical generator + diesel tank + batteries + electrical pump + electrical propellers.

Which it will work much better if we remplace the diesel generator + diesel tank + hellium by Solar Cells + Fuel Cell + Electrolyzer + small water tank + hydrogen.

Some links:

http://youtu.be/T4f89uJEhOE?t=3m23s (variable bouyancy graphic)

http://youtu.be/GceGS-g8hbI?t=1m10s (HPE real view and explanation)

http://youtu.be/zgZW5fuIlUs?t=57s (landing cushiond and structure lightness)

http://youtu.be/6alsthqayLo?t=3m24s (a vigilance concept that use fuel cell hydrogen combo pack)

The first models of aerocraft will be 4 of 66 tons 2017 and 22 of 250 tons finish by 2020.

I will try to help you in a game design system including all physics equations and logic (not code) using the modular envelope system and old airship methods.

Edited February 6, 2015 by AngelLestat

[RadarManFromTheMoon]

what happens if the ballonet is 100% deflated and you still rise altitude and speed?

In that case it would not explode, becouse it only takes into account the ballonet pressure, or I miss something?

Or maybe it takes into account some way the pressure applied on the ballonet from the main envelope and the external pressure?

Oops. What I really meant is not ballonet pressure, but envelope pressure. Since the ballonet can not deflate any further and athmospheric pressure decreases with altitude, the envelopes pressure relative to the outside pressure will rise, causing the hull to fail eventually. This would happen even in a rigid airship unless gas is vented (or stored otherwise) to avoid that. The pressure of the inflated ballonet is not taken into account at all at the moment.

The opposite case however would be the envelope getting compressed by increasing athmospheric pressure while sinking. There are two scenarios now:

A) The lifting gas is stored directly in the envelopes hull. The hull cannot counteract relative pressure changes since it is rigid. While sinking, the atmospheric pressure would start crushing the now underpressured hull. Inflating the ballonets prevents this by reducing the envelopes effective volume, thus increasing the pressure of the lifting gas. This is how PA currently works and it is a troublesome approach since ballonets would control both buoyant volume (lift) and pressure. The Aeroscraft works very similar but instead of controlling the buoyant volume with the ballonets, it compresses lifting gas into the "HPEs" and uses ballonets only as a pressure balancing measure.

the lifting gas is stored inside a bladder inside the envelopes hull and can expand freely, The volume not used by the gas would get occupied by air. Buoyancy control would only be possible through ballast and gas venting. It's the oldschool way of airship construction.

These are the problems I would say PA is facing at the moment:

-PA envelopes are blackboxes. You can not really look inside them so it is not easy to make sense out of the values provided by the right-click-menu. A Flight mode GUI with gauges would help a bit but besides that my vision for PA would be an editor that lets the player decide how the Envelope is structured inside. This way it would be possible to use various airship techniques or even try out new ones. The downside would be that it is not exactly a trivial task to realize something like that.

-KSP is a space exploration game so of course it would be nice to let player take their airships into space. Non rigid airships that can get inflated/deflated would be the solution. Again, not trivial to realize.

Thanks for your offer to help. It is very much appreciated. Are you fimiliar with fluid dynamics? The ideal gas calculations work quite well but so far, I was failing to grasp things like: How fast does a fluid flow from one vessel into another given a pressure difference and valve diameter. Or, maybe more important: How quickly does lifting gas temperature change in respect to athmospheric temperature/pressure changes.

Thanks for the headsup on the HAVOC project. Thats a really fascinating idea. Would be great if something like that would be realized within our lifetime. (I'm actually a bit pessimistic when it comes to bigger(or even manned) missions )

[AngelLestat]

The pressure of the inflated ballonet is not taken into account at all at the moment.

And I dont know why you will need it, the only that matters is how much volume is filled.

A) This is how PA currently works and it is a troublesome approach since ballonets would control both buoyant volume (lift) and pressure. The Aeroscraft works very similar but instead of controlling the buoyant volume with the ballonets, it compresses lifting gas into the "HPEs" and uses ballonets only as a pressure balancing measure.

I guess this is the main problem of PA. Ballonet main function is equalize pressure with the outside. Are not made to be used as a variable buoyancy control. Just micro adjustment to control the pitch in the cases where you have only 2 proppelers.

By micro adjusments I mean 2% (the exact value can be tested) max pressure difference on hull envelope with the exterior. If this is not enoght for the player, then he has to correct the center of gravity on the craft.

So the GUI must allow us to tweak how much we inflate or deflate the ballonets but without exceed 2% max pressure differences on the hull envelope respective to the outside.

The ballonets must always equalize automatically the pressure with the outside, it will be like presume there is a hole always open when air can enter or leave the ballonet.

In reality airships never explode due pressure, it does not matter if the pilot make mistakes or if the airships is able to reach higher altitudes or speeds which were not taken into account in design.. There is always many safety mechanism as vent valves that let lifting gas escape; or in the worst case, let air enter in the lifting gas envelope.

So a recomendation it will be include a vent valve, but the player may choose set it to automatic or manual.

A warning notification must alert us if we are lossing lifting gas.

the lifting gas is stored inside a bladder inside the envelopes hull and can expand freely, The volume not used by the gas would get occupied by air. Buoyancy control would only be possible through ballast and gas venting. It's the oldschool way of airship construction.

Yeah I know this method, but it could confuse the player if they also can choose the aeroscraft way.

-PA envelopes are blackboxes. You can not really look inside them so it is not easy to make sense out of the values provided by the right-click-menu. A Flight mode GUI with gauges would help a bit but besides that my vision for PA would be an editor that lets the player decide how the Envelope is structured inside. This way it would be possible to use various airship techniques or even try out new ones. The downside would be that it is not exactly a trivial task to realize something like that.

I like your idea, not need for a nice GUI, print all the values in a external windows will be enoght.

Hull Envelope Pressure, ballonet fill %, temperature inside, temperature outside, pressure outside (taking into account speed), lift force, altitude, amount and type of lifting gas in kg, external air composition??

I guess that is all, in SI units if is possible.

I know that is not a trivial task, but if you want I can help you with the logic and equations, so you can concentrate with the main issues like modular envelopes, etc.

-KSP is a space exploration game so of course it would be nice to let player take their airships into space. Non rigid airships that can get inflated/deflated would be the solution. Again, not trivial to realize.

Yet, that will be great, but there is no rush.. The key will be to know how copy some models and animations from Hooligan Labs in a way that can be scaled. For example with a cylinder shape (fixed ratio) which is the container of a fixed ellipsoid which size depends on the container.

Thanks for your offer to help. It is very much appreciated. Are you fimiliar with fluid dynamics? The ideal gas calculations work quite well but so far, I was failing to grasp things like: How fast does a fluid flow from one vessel into another given a pressure difference and valve diameter. Or, maybe more important: How quickly does lifting gas temperature change in respect to athmospheric temperature/pressure changes.

haha, hard question. I was looking into that and asking for help in the science section 1 year back, trying to calculate the heat loss on a airship due convection.

My conclussion, nobody really knows, no way to obtain accurate values. Heat losses due convection are too complex.

Things to take into account: shape, wind direction and speed, material, atmosphere composition, pressure inside and outside, temperature difference, etc.

The only thing that we can use to have an estimation, is that commonly heat looses due convection are higher than radiation in airships.

I will ask to DRE developers, they maybe can help. I will try to find an equation to approximate heat loses taking into account radiation, pressure, and speed.

In fact these calculations are made it only with proffesional software. Heat is one of the most elusive energy forms.

Sun radiation in this case would be a factor to increase temperature.

About hellium or hydrogen temperature change due expansion or compression, it can be ignored. These gases behave different that all the other gases, they heat up when they expand.

About gas flow, is not easy, but it can be done without problems.. You have to take into account gravity, pressure, gas type, CV of the valve, gas temperature and viscosity.

Then you have 2 different equations that are used, one if the source pressure exceed 2 times the destination pressure, the other if is not.

some info:

http://www.tlv.com/global/TI/calculator/air-flow-rate-through-valve.html (for air)

http://www.lmnoeng.com/Flow/GasViscosity.php

I can handle it. I guess the main purpose to calculate flow rate it will be to see how the pressure vary with time and how it equalizes by it self.

But not to let the player choose what size of valve he choose. I guess the valves needs to be automatic scaled depeding the envelope sizes.

I can find a simple equation estimation for all cases.

Thanks for the headsup on the HAVOC project. Thats a really fascinating idea. Would be great if something like that would be realized within our lifetime. (I'm actually a bit pessimistic when it comes to bigger(or even manned) missions )

I am more optimistic, I guess they will launch over this time frame: 2021 to the 2027.

In fact, it can be highly improve it.

[AstroRick]

I wonder if you could use SmartParts automation to automate all the lift control tweaking? This is a great mod, but I just want to point my airship in a direction and go, rather than micromanage. I suppose you could use MechJeb's spaceplane altitude control as well.

[Heckspress]

So now did 1.0 break this? I haven't even downloaded this and I'm already crazy about it. Sooooo much more realistic than Hooligan Labs.