Boats, Planes, and Math

[Story Books]

I've got a couple little questions. I'm sure they're probably under the category of "duh" for many people here, but I'm pretty new the the Kerbal community. The questions are as follows:

I've seen pictures here and there of boats made within KSP and am trying to figure out if there are any particular mods necessary to make most of these creations? I'm planning to make various craft for exploring planets with oceans on them and exploring boats as an option seems like an avenue definitely worth looking into.

Second, I've been planning to make a UAV using stock materials to explore Eve. That is until I learned that the atmosphere, while thick, does not contain the oxygen necessary for combustion and rendering jets useless. I had the idea to modify the existing UAV into a prop plane powered with electric motors (or something similar) I wondered what mods out there might support a build like this.

Lastly, I'd like to do some of the number crunching gain a better knowledge of rocketry in general. Especially as it applies to KSP. What are some recommended resources that I could look into?

Edited September 21, 2014 by Story Books

[UmbralRaptor]

1) The hard part is getting them into the water, but this is doable in stock. Parachutes or rover wheels are often involved.

2) Firespitter is I think the most common mod choice

3) How in depth do you want? Braeunig is a good general resource, as is wikipedia (you want the rocket equation*, Kepler's Laws, and the Vis-Viva equation in particular. For textbooks, I'm partial to Fundamentals of Astrodynamics

* note that for KSP purposes, g0 is 9.82 m/s²(!)

[GoSlash27]

You could also cheat and make an "infiniglider" UAV. Same effect as a photoelectric prop without using mods. Just add small control surfaces as propulsion units.

The #1 most important thing to know backwards and forwards is the rocket equation. If you have that down and can manipulate it to solve for any variable, there's pretty much nothing you can't do in this game.

Best,

-Slashy

Edited September 20, 2014 by GoSlash27

[Tex_NL]

Besides the electric propellers in Firespitter and the somewhat cheaty infiniglider you'll have at least two other mod options: Kethane and Karbonite.

Both have thrusters that burn the stuff directly. Kethane can only be mined in certain locations so exploring requires careful planning to refuel. Karbonite can be mined everywhere.

[cantab]

On boats, quite a few people have made them in stock. Buoyancy is really screwy but radial intakes float well and can be used for hydrofoil-esque craft. Wings work quite well too and are what I used. Most "normal" parts like fuel tanks will be very draggy in the water. For propulsion jets are super-efficient (but no good for Eve of course), and ion engines can work though they're low thrust.

I concur that Firespitter is the go-to mod for propellers, it includes a few electric ones. Kerbal Aircraft Expansioneers has an electric prop too. They work fine above or below the waterline, so you can use them for boats as well as planes. To power them bear in mind extended solar panels will rip off at any significant speed. I used a nuclear reactor from Near Future for my boat, but you can just pack plenty of batteries and land/glide/drift when you need to top them up, or coat your craft in OX-STATs.

If you want a pure stock plane for Eve, Duna, or Jool, your main options are unpowered glider, infiniglider, ion glider, or rocket plane. Ion gliders can be tough to make, especially for Eve, and I think don't tend to be fast. A rocket plane will probably be easier to build and more fun to fly, but you won't get much time with it.

[CavemanNinja]

As stated by Cantab above, Buoyancy is nonexistent and as such, your best option for a boat is lots of radial intakes covering the bottom, or good girder design. Regardless which you use, I would recommend electric props from firespitter that are near the waterline without being too far below the craft's center of mass, and a crap ton of RTGs clipped inside something.

Addressing the UAV, props from firespitter again and a literal metric ton of wing surface covered by solar panels (or the RTGs with smaller wing surface). If you're planning on flying at altitude on Eve, pack parachutes near you center of mass because landing planes that have high wing surface on Eve takes literal hours.

As for the "number crunching", Learn the Dv (delta V) formula, and if you can't be bothered memorizing planetary phase angles ksp.olex.biz is extremely helpful. I'm not sure what else you need rocket equation-wise (just for the basic stuff), except maybe terminal velocity to save fuel and gravity turn heights for various bodies. Consult the wiki for those.

Want to learn more about KSP maneuvers and processes in general, then look to none other than the Manley!!!

Good luck, and If you go the ion glider route don't forget the drop tanks!

(sorry for the wall of text )

Edited September 21, 2014 by CavemanNinja

[Story Books]

Lots of really good information here! Thanks for the help!

Looking at some of the equations, I think I need to pick calculus back up again. Something to give the brain a workout though. Should be fun!

[mhoram]

Lastly, I'd like to do some of the number crunching gain a better knowledge of rocketry in general. Especially as it applies to KSP. What are some recommended resources that I could look into?

Description of KSP-relevant physics is distributed on many places. I made an effort to gather them:

http://forum.kerbalspaceprogram.com/threads/93426-Physics-of-KSP

[Tw1]

There used to be a boat specific propeller, but the mod is no longer hosted anywhere.

Another important thing to take into account with boats, is anything that will be exposed to water, especially moving water must have a high impact tolerance. I like to pick things that have at least a tolerance of 40 for boats. Aeroplane cockpits and structural panels are best.

As mentioned early, parts become draggy when in water. So unless you need them for buoyancy, or can't place them anywhere else, keep things above the water.

Also, basic things like making sure your vessel is balanced apply.

[GoSlash27]

Lots of really good information here! Thanks for the help!

Looking at some of the equations, I think I need to pick calculus back up again. Something to give the brain a workout though. Should be fun!

Calculus isn't really necessary for what you need to do here. Pretty much Algebra II will suffice.

The only part that you need to know (and algebra II won't necessarily tell you) is how to reverse an equation containing a logarithm. ln(x) is algebraically the same as any other value when shuffling it around in an equation, but if you wish to solve for x, then raise "e" to the power of ln(x) to yield x. It works like this:

dV=blah*ln(x)

dV/blah=blah*ln(x)/blah

dV/blah=ln(x)

e^(dV/blah)=e^[ln(x)]

e^(dV/blah)=x

Otherwise... basic physics and a working understanding of trig will see you through.

Best,

-Slashy

[Progressm]

Luckily, with KSP, you can visit and return from all the normal places with barely any real understanding of the maths behind it...sure, you will probably haul around far too much fuel/mass but in a universe with no real economy to worry about that's hardly an issue.

I can talk, I have done it and I am a banker irl, i.e. I have barely any understanding of numbers full stop, let alone real maths.

Sure, bring able to crunch the numbers would help and would be fun...but in the meantime a delta-v map printout and kerbal engineer has seen me though fine.

Just putting in my 2 cents to prevent newbies from getting discouraged by the scary formulae above, no offense meant. :-)

[KerikBalm]

1)2) Firespitter is I think the most common mod choice

And if you don't like firespitter, its easy to mod yourself.

I haven't downloaded firespitter, but I did make my own "ducted electric fan"

I duplicated the basic jet (I almost never use that thing anyway), changed the name, tweaked the mass and cost, but the most important change was here:

MODULE

{

name = ModuleEngines

thrustVectorTransformName = thrustTransform

exhaustDamage = True

ignitionThreshold = 0.05

minThrust = 0

maxThrust = 30

heatProduction = 50

useEngineResponseTime = True

engineAccelerationSpeed = 0.5

engineDecelerationSpeed = 0.75

useVelocityCurve = True

fxOffset = 0, 0, 0.74

PROPELLANT

{

name = ElectricCharge

ratio = 45

DrawGauge = True

}

PROPELLANT

{

name = IntakeAtmosphere

ratio = 1

}

atmosphereCurve

{

key = 0 1000

key = 0.3 1800

key = 1 2000

}

velocityCurve

{

key = 275 0 0 0

key = 250 0.3 0 0

key = 175 0.7 0 0

key = 0 1 0 0

}

}

This requires you to make an entry for "IntakeAtmosphere" in resources.cfg.

It also requires you to add a source for it.

I added this to the circular intake (which I also use so infrequently, that closing the 2nd intake module is not a problem), but you could easily also add it to the engine itself so that it functions as a standalone unit:

MODULE

{

name = ModuleResourceIntake

resourceName = IntakeAtmosphere

checkForOxygen = false

area = 0.008

intakeSpeed = 10

intakeTransformName = Intake

}

RESOURCE

{

name = IntakeAtmosphere

amount = 0.2

maxAmount = 0.2

}

As a finishing touch, since the artwork changed between .18 and now, I took the model and texture from my old .18 install, and used that for the "electric ducted fan".

Its very similar but still visually distinguishable.

I think I made it pretty balanced... its velocity curve is very limiting (good luck getting past 250 m/s using them!), and it eats electricity pretty fast, but its useful enough (also I reduced the mass to only 0.4 tons, but its TWR is still much less than the basic jet engine)