Asimov's Three Laws of Orbital Mechanics

[Hotel26]

[I realize the following is going to be somewhat polemical...]

Asimov's Three Laws are:

1. Nothing accelerates (artificially) without fuel.
2. All fuel comes from Earth (Kerbin).*
3. Every launch from Earth MUST carry the maximum load of fuel possible.

* Asimov wrote this before the advent of "mining/refining" in KSP [whichever version that was...]

There's a catch-cry joke in space-jock circles, "moaah boosters!!!"...  [subtext: "you don't even know what your delta-V is, nor how to use a slide-rule."]

Somebody long ago in this forum asked about standardizing an orbit delivery system [the gist].  The answer was an emphatic, resounding, "you cannot.  every [keyhole, bespoke] mission is different!"!.

I'd like to opine this has been the NASA 1960s vision and it is the reason that space is now being privatized and modularized.

My goal has been to conquer the Kerbolar system using a tightly-coupled architecture employing the minimum number of components.  There are about seven components in it so far, covering a wide panopoly of purposes.

Launch vehicles from Kerbin: just two.  Two.

1. Minotaur super-tanker is designed to blast 35 tonnes of fuel up to an LKO space dump (yes, it is nothing but a fuel dump and a rendez-vous for assembly of interplanetary expeditions).
2. Aquila is a general-purpose payload deck (7 slots) that triples as a gangable interplanetary injection booster and orbital fuel tender.

I build whatever payload I need on top of Aquila and then top up its payload with extra fuel to deliver to the Kerbin space dump for assembly and fueling of interplanetary missions.

As R.A. Heinlein put it: "once you reach Low Kerbin Orbit, you are halfway to anywhere..."

Or as the sign on George H.W. Bush' desk stated: "It's the fuel, dummy."

Edited November 3, 2017 by Hotel26
emphasis

[Hotel26]

Erratum:

Falcon is a recent addition and is a space-plane capable of taking 4 crew and 16 pax to LKO.  It's also believed capable for deployment on Duna, Laythe and, in some limited manner, maybe on Eve(?).

So, OK, three.    Falcon was just for fun and not considered essential.  It might get a promotion subject to successful testing on Laythe.

Edited November 3, 2017 by Hotel26
clarification

[Rocket In My Pocket]

So, I'm confused...is this a mission report or...?

[DrLicor]

4 hours ago, Hotel26 said:

Nothing accelerates (artificially) without fuel.

He also wrote this before the ion drives?

[Urses]

38 minutes ago, DrLicor said:

He also wrote this before the ion drives?

They are non magical, they have fuel.... it is named only other way to summarise confusion for uninvited

[DrLicor]

1 hour ago, Urses said:

They are non magical, they have fuel.... it is named only other way to summarise confusion for uninvited

Yep they have xenongas, but it's the electricity that's doing the work. 

The Deep Space 1 spacecraft, powered by an ion thruster, changed velocity by 4.3 km/s while consuming less than 74 kilograms of xenon. The Dawn spacecraft broke the record, with a velocity of 10 km/s.

[Hotel26]

10 hours ago, DrLicor said:

He also wrote this before the ion drives?

Ion drives are great.  (I use them in packs of 24.)  The amount of delta-V you can pack on a flight is almost like cheating.

Yes, technically, xenon does not provide energy, yet it is an essential consumable.  Ion drives will also not get you off Kerbin as they are just payload for that first half of the journey.

It doesn't change the thesis: especially as, unfortunately, you cannot mine/refine xenon in KSP: the only source is Kerbin.  The thesis is that launches are expensive (on time) and should achieve multiple objectives and be designed for a standard lift-off weight, not tailored to the payload or to a mission.

I use almost exclusively nukes and ion after just shortly before reaching LKO.  The exceptions would be a small lo-grav lander used as personnel/ore carrier and that space-plane, if I ever send it somewhere else.

I am sure that there are many Kerbonauts who have gone this same route: assembly/fueling in LKO.  I'd wonder what the percentage is, especially amongst the grizzled veterans?

Additionally, I want to invite sharing of ideas by any who have gone the route of assembling expedition vehicles in LKO.

P.S. I was quoting Irving Asimov, just to avoid confusion... 

Edited November 4, 2017 by Hotel26
add invitation

[Archgeek]

On 11/3/2017 at 5:48 AM, Hotel26 said:

Asimov's Three Laws are:

1. Nothing accelerates (artificially) without fuel.
2. All fuel comes from Earth (Kerbin).*
3. Every launch from Earth MUST carry the maximum load of fuel possible.

* Asimov wrote this before the advent of "mining/refining" in KSP [whichever version that was...]

Curiously, those laws have lost a bit of their strength.

• 1 can be broken outright with a solar sail or electrosail.  Ion drives and technically NTRs break it too, but they still need remass, which is probably we can assume he meant.
• 2 as you note is partially broken by the advent of ISRU, but since a few of our favourite fuels are cryogenic (take your pick), have a habit of drifting right through solid metal tank walls (lH2, and corrossively, at that), or just aren't very available upstairs (xenon, uranium/plutonium/thorium), we are still somewhat bound by that one.
• 3 honestly sounds more like a conclusion based on the first two -- but it at least still makes sense if we stretch it to max payload.

More curiously, the nature of KSP means that oft-times the ability to create a bespoke lifter for a mission can make it better follow #3, in that, instead of winding up with a few tonnes of capacity left putting a 27t payload on a 30t-cap lifter and having to fill those remaining tonnes up with a few little gas tanks that'll get drained and possibly thrown away, we do have to option to create a special 27t-cap lifter, simply because we can build and roll out new craft so very, very, fast.

[KerikBalm]

Fuel and propellant are not necessarily the same thing.

Also... who is Irving Asimov? Is this a parody of Isaac Asimov's 3 laws of robotics? What is this thread? I'm confused.

[Hotel26]

Actually, I really do apologize for the confusion!  (And KerikBalm: spot on and well done!  "Irving Asimov" is one of my many nommes des plumes.)

I guess there are definitely two schools of thought about rocketry.  And I admit I have a bee in the bonnet about "architecture".

I read ArchGeek's opinion and example above with respect but was not at all convinced -- in fact I want to use his example as my own!!  When I reach my 90x90km fuel dump, any excess fuel is siphoned into the dump for future use.  As he says though, "Law" 3 is definitely an ergo conclusion.

Here's a thought: my space dump is actually put together from parts scavenged from the first two super-tankers that come up to establish the dump.  The super-tanker has a hex-connector and a small lander mounted atop and that is enough for the tanker itself to perform some gymnastics to shed some orange tanks that then become a giant ten-dock rig constructed purely of 24 orange tanks about 10 monoprop tanks and the 2 hex connectors.

In other words, I think my motto is "never do anything in space that doesn't achieve at least two objectives".  You can quote me on that!  (Just spell it correctly: "Irving Asimov")

[wumpus]

Now with modern computers doing the navigation calculations:

LEO is halfway to anywhere (in the solar system).  L2 (Earth-Moon Lagrange point 2) *is* anywhere in the solar system, or at least needs stationkeeping thrusters to fly various gravity loops to get anywhere. https://www.nasa.gov/mission_pages/genesis/media/jpl-release-071702.html

I'd love to say that ions can take you from LEO to L2, but that Van Allen belt is nasty (current ion craft have been boosted to escape velocity by chemicals).  Solar sails might make more sense.

Once you've sufficiently broken the rocket equation with tricks like these, fuel doesn't become the overwhelming requirement anymore.  It might be huge, but everything else can now compete for those precious tons.  Note this only applies for cargo, these tricks are far to slow for crew.

[Rocket In My Pocket]

Not to disagree with the OP, but it takes me about 5 mins tops to slap together a custom launch vehicle for my payload.

There just really isn't any compelling game play reason to make a suite of stock launchers in my opinion.

I also don't see any compelling game play reason to "make the most of every launch" except your personal time investment? I tend to make the absolute least of each launch, so I can have more launches, and play more...cause it's fun? To each his own though, efficiency and minimalism has a certain appeal.

[KerikBalm]

3 minutes ago, Rocket In My Pocket said:

Not to disagree with the OP, but it takes me about 5 mins tops to slap together a custom launch vehicle for my payload.

Yea, its not too hard to slap together a custom launch vehicle. Its a lot easier with a readout like KER supplies.

Quote

There just really isn't any compelling game play reason to make a suite of stock launchers in my opinion.

If you're playing without any dV readout mod, it can make sense. It can also be convenient later, saving 5 minutes each time adds up. If you're using spaceplanes, it makes a lot of sense (and you may use those if you play with limited contract payouts, or just 'cause you like them).

I play on a 3x rescale now (and some other tweaks), so spaceplanes have a smaller payload margin, and need to supply a lot more dV.... as a result... my heavy lift spaceplane is quite a bit larger than it was for stock kerbin... I spent a lot of time tweaking it to get it flying right... I am not going to put these sort of spaceplanes together again each time I want to lift a payload.

\

Spoiler

And... of course, a payload of that size isn't always needed, so I did make smaller size SSTO spaceplanes:

Here is a smaller one refueling from the larger one, its going to be a cargo shuttle for another world (Rald, my mod):

 

Of course, when my standard launchers (rocket or spaceplane) reach orbit with extra fuel, I don't go out of my way to have them go maneuver to a fuel depot and deposit it in orbit. If I bring up some excess fuel payload, I bring it back down or I burn some of it before releasing the payload to lower the dV requirements of the payload (ie if I have 50 spare* m/s when in orbit, I'll burn those 50 at the right place so that the payload's first burn can be reduced by 50 m/s. * spare meaning that I can burn those 50, and still de-orbit my launcher, not leave it stranded in orbit). Part of having a standard launcher is knowing that it will be a bit overbuilt for most payloads.

And of course, many of my "standard launchers" aren't so standard, I just start with a standard and make a few tweaks specific to the payload - its faster than building an entirely new rocket.

[Rocket In My Pocket]

1 hour ago, KerikBalm said:

-snip-

Well, obviously Spaceplanes are a different story, and must be designed with a set payload weight/cargo size in mind, they also represent a significant increase in development time. It's like comparing apples and oranges.

Also, yeah I'm assuming most people play with KER; so slapping together a 3 stage rocket under a given payload should be trivial. As I also mentioned, I just plain enjoy actually playing the game; I'm not looking to "skip" parts of it by being efficient. On the contrary, I'll spend hours designing a new/different craft just to send one Kerbal up to a station when I already have a better craft designed for that...for no reason. Just because.

That said, most of my "custom" launchers do follow a very similar profile but that's mostly down to having figured out what works best through experience. Pre-designed launchers certainly have their place and merits, for some people; but it's definitely not a "rule" of KSP.

Edited November 9, 2017 by Rocket In My Pocket

[KerikBalm]

Well, at some point I got really enthusiastic about payloads designed to fit "standard" vehicles.

After developing my standard SSTO launcher, I made an interplanetary craft/base/station from sections (assembled in orbit), all of which were compatible with the standard SSTO:

Spoiler

First module:

Early stage:

Intermediate stage:

I also wanted fully relocatable surface bases, so then my surface bases are all made of modules which fit in a standard cargobay. Mostly the surface base modules are standard, only varying as appropriate depending on availability of water/CO2/O2 (With TAC-LS), and of course power generation must be adjusted the farther one gets from the sun. Although... the base modules did evolve when I tried to optimize part count vs capability, and I wanted a larger base for my main colony on the surface of Rald.... still all the base modules are compatible with each other.

Spoiler

(That tanker on the left is not standard, but it did fit in the standard heavy SSTO launcher - with some tweaks)

All stock base modules:

Those big all stock modules can connect to the KPBS modules at the orange tank adaptor... which can also show how I'd made a surface base out completely stock:

like this really old design of mine:

Of course... there are some designs that really do need a custom launch system... like those cargo spaceplanes for moving stuff around on Duna and Rald (in the 3x rescale, they cannot self launch)

Spoiler

These "Standard Cargo" SSTOs for other worlds, in the 3x gameplay, require unique and expensive launchers:

The Rald one

 

The Duna one:

^ That one has modded ramrocket engines, those aren't afterburning panthers on the spaceplane.

And I've also made some pretty big relays for use with OPM, with the range buff turned off... those needed custom launch vehicles:

And... sometimes the payload is small but oddly shaped.. in such cases the massive SSTO could life it, but I don't want to bring it out for those cases, so I do a custom launching rig... which I could make standard for these sort of sub-sonic winged craft

Spoiler

If interested, those scaled down goliaths are now electric fans... I've since changed their color to make it more obvious

These are also candidates for a cersion of that launcher:

I'm satisfied with the ram/turborocket recolors here (brownish-red tint)... but the liquid propulsion(blue tint) and electric fans(green tint) are too colorful... I need to go back and make them more subdued:

 

 

[Hotel26]

On 2017/11/10 at 1:42 AM, Rocket In My Pocket said:

I also don't see any compelling game play reason to "make the most of every launch" except your personal time investment? I tend to make the absolute least of each launch, so I can have more launches, and play more...cause it's fun? To each his own though, efficiency and minimalism has a certain appeal.

Perhaps we are in agreement?

Instead of sweating the details with a tailored, bespoke, orbital delivery package, perhaps we tackle the grand design challenge of one-size-fits-all*.

But "oh. no!  isn't that wasteful?".  No.  Because one simply slops extra payload into the fuel tanks to make up a full delivery to space.  Every launch is expensive.  (My time is not cheap!)  Make every launch deliver the full punch to orbit!  Without any thought or effort...

The vehicular payload [whatever it is] is freed from Kerbin...  And the OFD [Orbital Fuel Dump] gets its tanks topped-up with the surplus.  Maximum benefit for least effort, including most efficient design effort.

[I have a reason for digging up this coffin during the wee hours of a new moon!!  "What if Irving was wrong?"]

*  And the funny thing is that I suspect we've all attempted a "Grand Unified Theory Launch Booster Vehicle"...!?!!!  (I'll show you mine, if you'll show me yours!  ]

 

Edited January 13, 2018 by Hotel26

[Hotel26]

A few months back, I tried assembling and fueling a mission around the Mun.  I think what I concluded was that the combination of the Mun's Kerbolar prograde velocity plus one's own Mun prograde velocity wasn't as much as in low orbit around Kerbin.  So I tried using the Mun as a starting point and then doing a Kerbin fly-by (using Oberth as well) to sling-shot the maneuver.  Of course, it makes everything a bit harder.

The question, is: what if gas was 1/4 of the price on the Mun that it is on Kerbin?  Would it be worth it?

So then a question is, what if you had a base in orbit around Kerbin at say 500 or 1000km.  You brought equipment up from Kerbin to assemble and refuel it.  But the fuel came from the Mun at a much cheaper price?

Edited January 13, 2018 by Hotel26

[suicidejunkie]

If you want cheap gas, then Minmus is the place to get it from.  6x LV-Ns with a dedicated 1500 LF each will haul 200 tons of cargo fuel to Kerbin and Mun with enough left to return and land at the refinery.

I threw enough docking ports and auxiliary bits onto the tanker so they are basically LKO/LMO fuel stations that take a two week vacation once per year or so, to go get themselves more fuel.

In contradiction to the laws mentioned, these monstrosities launch with the minimum amount of fuel for safety, lob high and spend a long low thrust burn circularizing with the LV-Ns before trundling off to Minmus.