[WIP] APU/EPU, RAT, and Fuel Cell [16 Jan 15]

[Ignamious]

Over the course of the next few days i am going start making an APU / EPU / RAT.

APU = Auxiliary Power Unit.

An APU is a term used for the production of power not used in propulsion. So the Alternators on Engines of cars, or on rockets, are not APU's however Fuel Cells used to power life support, electronics, and Hydraulics would be.

These are generators, they are used in most big vehicles, From Trucks to Tanks, Airplanes and Ships. The STS had many different kinds, the Apollo had 3. The LOX tanks that blew on Apollo 13 were for the APU (AFC's).

EPU = Emergency Power Unit.

Same as the EPU but as a backup. Many use Hydrazine.

RAT = Ram Air Turbine

These are mostly used in Airplanes. Think of it as a small wind turbine. These are the last things used when the Main Gen., APU, and EPU fail. Its enough to power critical systems.

This mod will be for real world power units to augment those lacking in KSP. While the RTG is fine, i just find it lacking, as the heat is not modeled. (fuel attrition is moot.) and with deep space refueling coming, i think these will fit nice. They will be early in the tech tree to augment until the RTG.

Part of a realism mod i guess.

The APU/EPU/Fuel Cell(Auxiliary Power Unit / Emergency Power Unit) will be coming in a few different models and be the first ones out:

A radial one similar in size to the PB-X50R Xenon Container

A Tiny one similar in size to the PB-X150 Xenon Container

A Small one similar in size to the FL-R25 RCS Fuel Tank

Download 0.01

Change Log

WIP 2 (0.01)

[LIST]
[*]Added MonoPropellant Fuel Cell
[/LIST]

WIP for Inline Fuel Cell. Colors are only to see detail.

if there is demand for it, a Large Size one as well.

I’ve been trying to come up with a plan of attack on the Fuel, and have come up with the idea of just following NASA, and use the KSP Equivalent of Monopropellant. These APU’s will be a realism replacement for the overpowered RTG. The APU/EPU will be self contained units, meaning they will have enough fuel in them for 6 Hours. They are only meant for use for accent, orbital insertion and decent. In the Space shuttle they used them for the Hydraulics. They can be used for other applications.

Talk about the power generated by the Fuel Cell Vs APU

The RTG used in the Voyager 1 at launch was 400W at 30VDC thats 13.3A Each or 40A for all three (it’s less now) assuming the unit of measurement for KSP’s power is 1 = 1A that would mean the Voyager 1 Probe at launch in KSP terms generated .01/s

If we use the same for the RTG in game we get .75/s or a total Generation of 2700A at 30 V is 81000W. However if we assume that the Electric charge is in mA not A we get the KSP RTG is now 2.7Ah at 30V so 81W thats inline with the Apollo 12–17 ALSEP RTG.

Voyager 1’s RTG (single) in KSP: E = 3.7/s

ALSEP RTG in KSP: E = .65/s

ok so i have a precedence for the amount of power an RTG uses in KSP, how do i use this for the Fuel Cell, APU and RAT.

The Apollo Era Fuel cell was 30 VDC 1420 Watt with a peak of 2300 watt.

Dimensions

3-D: 111.8 x 55.9cm, 111.1kg (44 x 22 in., 245lb.)

Baseline established for Fuel cell in real life, so KSP terms its:

13.13/s (ignoring peak)

Perfect now i need to scale this for KSP. Well, at 55.9cm wide we see that the apollo fuel cell is a kSP tiny.

Now the Fuel. The cells were fed by two hemispherical-cylindrical 31.75-inch (0.806 m) diameter tanks, each holding 29 pounds (13 kg) of liquid hydrogen, and two spherical 26-inch (0.66 m) diameter tanks, each holding 326 pounds (148 kg) of liquid oxygen (which also supplied the environmental control system).

(taken right from wikipedia, couldn’t find NASA source on this one.)

so for the usage of fuel it should be (simplified a H=1 O=16) by weight of 1:8

so for each 1/kg of Liquid Fuel used 8/kg Oxidizer need to be used. but this won’t add up as in KSP it’s 8 units of liquid fuel per 11 units of oxidizer

thats more like RP-1 and Oxygen, wile this type of Fuel cell has been created it’s runs Much to hot to be used, and is more expensive. to combat this we will fudge some numbers to make it work.

As i don’t know C# to be able to do any major code, i’ll use the already implemented .cfg files to do what i want.

So Fuel cell in KSP:

Size: Tiny

Output 13.13/s

Fuel 8.6 kg Liquid Hydrogen / 68.8 kg Liquid Oxygen

Won’t work. To powerful for KSP. So, Lets change it.

So Fuel cell in KSP:

Size: Tiny

Output .0457/s

Fuel Used:

LiquidFuel = .0009

Oxidizer = .0011

This means with a full FL-T100 you can create: 2.285 Amps of charge or in KSP 2285 E units and will last 13H53M20S. While making this fuel Cell powerful, it also makes it semi-balanced. The other option is to decrease the fuel usage 10%, but this would make it be able to charge 22850 and last 138H53M20S

Now this would make the timeline more correct for the Apollo Erra, and the charge balanced for KSP.

Well, thats that taken care of. So, where to put it. Well, it will have to be in somewhere between batteries and Solar Panels for the first small one. Now, as the size increases so could the power output, but this would also scale the Fuel usage. Relatively easy.

Now the APU is a different beast. It will use Monoprop at a higher rate, but also has an increased power output. for the Boing Dreamliner the APU will generate 235kVA 235VAC (guessing three phase) is 614.2A!! that would be a charge rate of 170.6/s. That kind of charge just isn’t needed in Stock KSP. as we don’t have to worry about using them to power all the lights on a plane, and the cabin avionics and sensors. KSP doesn’t model amount of current needed just to run a command pod (yet).

“Put them at the end of the tech tree!†Why? Whats the point in that, by then you can have RTG’s. Besides fuel is a premium in the start.

the RAT. Ok, this is a Ram Air Turbine, this is the last ditch to create electricity if both the Batteries are empty and the APU is out (in real life, this would be used if both engines are down, and the APU’s won’t start) and all planes have them (well not crop dusters) it’s a propeller that pops out somewhere on the planes and creates just enough power to run the critical systems. The faster you are gowing the more current is created. this would only work where there is an atmosphere (something to make the propeller spin) so Kerbin, Duna, Lathe, Eve.

Will update when i have Proof of concept parts done and post them for Balance review. Right now i have the Fuel Cell complete, using the RTG, i’ll change this to the above objects later.

This should fill a void in some of the Aerospace realism parts that are missing as all jets (that i know of) and planes (Militart and medium+ commercial) have APU/EPU and most space craft have Fuel Cells (the Space shuttle had them, as well as the Apollo CSM and Some Probes. and the RAT’s most commercial planes have them. Can’t find documentation on if the Space shuttle had one, but i don’t think it did. Air Transat Flight 236, an Airbus A330 used a RAT to perform a deadstick landing in the Azores. and in KSP many a time i have landed my plane, shuttle, SSTO deadstick, and 80% of the time, the reason for less then safe re-entry was running out of electrical charge high in the atmosphere. while a RAT won’t help me there, i could have used an APU/EPU until lower, and avoided a retrograde facing re-entry. FAR doesn’t like those.

-Jeremy

Found good read on Fuel Cells from NASA: The Fuel Cell in Space: Yesterday, Today and Tomorrow by Marvin Warshay and Paul R. Prokopius

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900002488.pdf

Edited April 5, 2015 by Ignamious
Added clarification to the term APU

[Ignamious]

Added download link for POC Fuel Cell.

the file is for an alkali fuel cell. it uses the RTG from stock as a model for now.

[Drew Kerman]

just wanted to say I find this all very interesting. have it listed for future modding consideration depending on how things progress

[CaptainKipard]

I just want to know what this without reading the whole post. Could you add a clear, short, to-the-point description?

[Ignamious]

I just want to know what this without reading the whole post. Could you add a clear, short, to-the-point description?

Sure, I'll add that, I Forget that not everyone lives in a world of acronyms like i do.

[Ignamious]

Added the MonoPropellent Fuel Cell POC.

Not that great at modeling parts so that will take some time... I still would like to make them radial instead of inline, but i know that has fuel flow problems, hope to solve that for the Rocketfuel.

[Ricardo.b]

very uselful mod

this is very used in real life but just a few mods offer it

EDIT: the last uptade was my birthday

[Sampa]

Over the course of the next few days i am going start making an APU / EPU / RAT.

APU = Auxiliary Power Unit.

These are generators, they are used in most big vehicles. from Trucks to Tanks, Airplanes and Ships. the STS had many different kinds, the Apollo had 3. APU's Create the electrical power for systems. The LOX tanks that blew on Apollo 13 were for the APU.

Actually, the LOX tanks that blew up on Apollo 13 were for the fuel cells, not the APU! Apollo spacecraft did not carry an APU. Just a heads up on the facts

[Gaalidas]

Well, then... I guess they should have had one. If they'd has an APU on board, then the facts would fit our much-more-plausible illusions of what actually happened, which is obviously more entertaining than what really happened. Now that the truth is out, we're going to have to go through all the trouble of inventing a time machine, going back in time, and convincing the designers of the Apollo program to put an APU on board so that the tanks can blow up for the right reasons again. There goes my summer.

[Ignamious]

Actually, the LOX tanks that blew up on Apollo 13 were for the fuel cells, not the APU! Apollo spacecraft did not carry an APU. Just a heads up on the facts

APU is a Blanket term. Auxiliary Power Units is a device that provides power in vehicles for applications other than propulsion. In KSP stock, solar panels, and RTG's are APU's as long as they don't power the propulsion, so not on rovers or Ions. IF I remember correctly the APU's on the Apollo 13 where AFC's (Alkaline Fuel cell's) or Bacon cells. They used Pure Hydrogen and Oxygen to produce Water, Heat and Electricity. When both tanks blew they lost the use of the AFC's. Fun fact! that O^2 tank that blew was originally supposed to go on the Apollo 10.

When a Plane is on the ground, and it's main engines are turned off and it's not connected to ground power, Most have APU's that can start the turbines. They are called JFS (Jet Fuel Starter)

What Apollo really needed was an EPU. Not sure if Hydrazine was available, but a little of that with water, and pass it over an iridium catalyst to drive a turbine and you can charge the batteries. (Though the EPU's are generally to regain hydraulic pressure after them main gen on the turbine goes out, usually due to engine failure). Normally EPU's are seen on single engine craft, like the F-16C/D.

the Fuel Cell APU is seeing more commercial use too. Delphi Trucks put them on in 2012.

Normally you won't hear the term APU used for the only power generator. Such as the Apollo SM. As the AFC were the main source of power for the craft, they would be considered the SPS (Space Power Systems) or FCPP (Fuel Cell Power Plant).

Sorry for the confusion or the terminology. I'll amend the OP to say that APU will be a blanket term used for all power generation not used for propulsion of a vehicle.

[JeffreyCor]

Very useful! The Ram Air Turbine will be particularly good for some aircraft and spaceplanes for power during landing approach when the throttle is too low to provide effective power generation.

[Ignamious]

The RAT is the one i'm having trouble with, as i haven't had a chance to sit down and really figure it out, early attempts failed, but i had an idea last week, now i just have to get some free time. i should just sit down and learn C# and make a plugin. i've been delving into VBA for work, and already know enough C to get into trouble.

[rpayne88]

Looks great, but...

A few minor explanation details:

APUs are mini jet engines that are used to provide bleed air to the main engines. APUs are electrically started and blow air through the main engine's turbine, causing it to spool up before fuel is injected into it. Although most APUs have a seperate generator attached, most aircraft generate their electricity from generators attached directly to the engines. The APUs, after starting the main engines, are usually turned off to save fuel. Usually, they are only turned on in flight in the event of an emergency.

RATs are a plane's last ditch attempt to generate electricity. If the APU is inop for whatever reason, a small RAT will drop out into the airflow.

Like I said, this post was just to explain what they are. It would be interesting though to see the need for an APU in order to start a jet engine on the runway, though.

[Ignamious]

Looks great, but...

A few minor explanation details:

APUs are mini jet engines that are used to provide bleed air to the main engines. APUs are electrically started and blow air through the main engine's turbine, causing it to spool up before fuel is injected into it. Although most APUs have a seperate generator attached, most aircraft generate their electricity from generators attached directly to the engines. The APUs, after starting the main engines, are usually turned off to save fuel. Usually, they are only turned on in flight in the event of an emergency.

RATs are a plane's last ditch attempt to generate electricity. If the APU is inop for whatever reason, a small RAT will drop out into the airflow.

Like I said, this post was just to explain what they are. It would be interesting though to see the need for an APU in order to start a jet engine on the runway, though.

For Aircraft thats correct, APC / tanks it varies, some use turbine, others use two stroke engines. if you look at big rigs trucks, they have an APU. Most are diesel piston, but some are switching to hydrogen fuel cell. there is even propane. Stationary objects can have them too. APU is a term used for the production of power not used in propulsion. The Space shuttle's APU was for hydraulic pressure for the flight surfaces. On STS-9, two of Columbia's APUs caught fire due to a hydrazine leak, but the craft landed successfully. Hydrazine is nasty stuff, but useful, word in the pipe is they found an alternative but we'll see.

Also, on crop dusters RAT's are used to power the centrifugal pump so that the plane does not have to be modified so it can meet FAA standards. RAT's create drag and therefore are not used on anything else. I look hard to find any reference to it being used on any other type of vehicle but found nothing. all i found was references for APU's being used on everything, including trains, planes, automobiles, boats, spacecraft, and buildings.

[Sampa]

I'm not so sure that a crop duster would have needed a RAT! They are small planes that could, in a pinch, land quickly enough and only fly in the day time, so they can fly visually. They don't really use electricity other than to get the engine going. Just my thoughts.

[Ignamious]

It's not for Aircraft power, it's only for the centrifugal pump for the insecticide.

http://www.hydrogenappliances.com/AIRBORN.html

- - - Updated - - -

I've done a great deal of research into this, Actually what started me on making this in KSP was that i was looking into making one for myself. Just for S&G. I even have a crude Hydrogen splitter. Just trying to do it without all the expensive components.

http://www.fuelcellstore.com

Would like to use it for camping or to make my electric buggy. Was also thinking that it would be fun to use in RC planes using FPV. There is already a long-distance radio to use.

Sadly, most of this is DIY and VERY low budget, so all concept for now. Two more years.

[Bill nye the rocket guy]

i have a couple questions.

Will the apus also work with jet engines?

Will the apus di things like bleed air (if they're going to be in) for the jets?

[Ignamious]

i have a couple questions.

Will the apus also work with jet engines?

Will the apus di things like bleed air (if they're going to be in) for the jets?

I looked at 1.0's FuelCells, and they are far more powerful then what i have.

My model was 13 hours and 2,285 total charge for one FL-T100, while Stocks are 37 hours and 198,000 total charge. I think thats a little high, considering modern progress, but perfect for stock (have you seen the solar panels?!)

I still plan on working this, just can't find time (would rather play >.>)

As for the bleed air, i don't know if i'll model that, not sure it's really needed in KSP. But if i ever get around to learning C# (Still fiddling with VBA for work) i thought about modeling a realistic power mod, where the jets would require X electric charge and an APU to start them, or X intake air speed (i think the A-10C is around 130 to restart after flameout, but i can't remember right now). i know others have modeled the solar panel drop off, but i think thats something else that i would like to have.

One other thing, is the Stock fuel cells aren't generating any significant heat, at least in Kerbal atmosphere (on launch pad), i only see around 2 point increase in temp: vas Temp Ex: (Debug menu) in reality Fuels cells get HOT, so i would expect them to at least add 100 when at 100%, and the array was around 23 points (i would expect it to be 300+ min) (even though it's 12X more powerful for only 6x the cells).

Don't get me wrong, RoverDude did a great job with them, i like the model he used on a gameplay stand point, they actually look like Kerbalized versions of some forms of fuel cells, not sure about the ventral fins for cooling in space but *shrug*. They also generate a good amount of power, 2x that of the RTG (rate = 0.75) (I want to update that too use the same module the Fuel Cells use, ModuleResourceConverter vs the old ModuleGenerator) so it has a life span (of 15 years)

i'll have to play with them more, only had a few hours with 1.0 career, just unlocked Level two R&D so a ways off still.

[MasseFlieger]

I looked at 1.0's FuelCells, and they are far more powerful then what i have.

My model was 13 hours and 2,285 total charge for one FL-T100, while Stocks are 37 hours and 198,000 total charge. I think thats a little high, considering modern progress, but perfect for stock (have you seen the solar panels?!)

I still plan on working this, just can't find time (would rather play >.>)

As for the bleed air, i don't know if i'll model that, not sure it's really needed in KSP. But if i ever get around to learning C# (Still fiddling with VBA for work) i thought about modeling a realistic power mod, where the jets would require X electric charge and an APU to start them, or X intake air speed (i think the A-10C is around 130 to restart after flameout, but i can't remember right now). i know others have modeled the solar panel drop off, but i think thats something else that i would like to have.

One other thing, is the Stock fuel cells aren't generating any significant heat, at least in Kerbal atmosphere (on launch pad), i only see around 2 point increase in temp: vas Temp Ex: (Debug menu) in reality Fuels cells get HOT, so i would expect them to at least add 100 when at 100%, and the array was around 23 points (i would expect it to be 300+ min) (even though it's 12X more powerful for only 6x the cells).

Don't get me wrong, RoverDude did a great job with them, i like the model he used on a gameplay stand point, they actually look like Kerbalized versions of some forms of fuel cells, not sure about the ventral fins for cooling in space but *shrug*. They also generate a good amount of power, 2x that of the RTG (rate = 0.75) (I want to update that too use the same module the Fuel Cells use, ModuleResourceConverter vs the old ModuleGenerator) so it has a life span (of 15 years)

i'll have to play with them more, only had a few hours with 1.0 career, just unlocked Level two R&D so a ways off still.

I would be totally down with this, having to deal with the APu to start a jet engine and so on would be aweome. Do you need n\any help ?