Pyramid #3/79: Space Atlas
 

From our sunny home
Outward into the heavens
To worlds round the stars

— A cosmic explorer

Roleplaying campaigns require settings – and with few exceptions, settings need details to be interesting. "The story of the people with no background in the land with no place names" is rarely very exciting or memorable! Creating and elaborating on a world is a lot of work, however – especially when it's a literal world hanging in space, around its own distant star, to be reached using speculative technologies. You really can't assume anything in that case, which can mean a lot of long nights (and caffeine) for the GM.

Fortunately, GURPS has always been good about providing resources to help out. GURPS Space offers systems for working out the details of faraway star systems and planets, and of alien races and their civilizations. If you go further back, you'll find the whole GURPS Space Atlas series. And now there's Pyramid #3/79: Space Atlas:

• What do you get when you combine hermaphormorphic parahumans, fringe religion, a civil war, a psi-disease infestation, and self-aware colonies of altered humans living with dinosaur-like creatures? The answer is Ostara, a world tailor-made for exciting adventures. David Pulver headlines this month's issue, providing a believable history for this strange planet, plus full planetary statistics, two racial templates, a new disease, and three unique examples of fauna.
  
  
• Every sci-fi game needs the occasional "mystery star system" where things are spooky and strange, and Christopher Rice's The Vanishing Sun will certainly leave your players scratching their heads. This system appears on no charts, draws travelers from across the galaxy, converts people into eternally young "Quicksilver-Born," and even features a massive, enigmatic cube floating out by the asteroid belt. Better start untangling these puzzles now!
  
  
• History and myth are rife with oracles – strange, special folk who offered insight that seemed to lead people to their fate. Introduce this concept to your games with The SkipTime Hub of the OceanWe. J. Edward Tremlett's OceanWe can divine the choices any person or race should make, and their motivations aren't even sinister. But the source of their abilities is also the catalyst for a division within the OceanWe – one that may turn bloody, drawing in half the galaxy.
  
  
• In many campaigns, the specific details of travel time are handwaved or simplified: your reactionless rockets or warp drive get you there "in time." But if reaction mass, orbital transfers, and delta-V are important considerations at your gaming table, you may need more than what even GURPS Space and GURPS Spaceships provide. Halfway to Anywhere tackles the math of orbital mechanics head-on, with clear formulae, guidelines, look-up tables, examples, and more.
  
  
• How would your campaign change if faster-than-light travel was impossible . . . except via one specific artifact of limited use? Homeword Unbound introduces the Archway, a gate capable of transferring one person from anywhere to Earth – always back to Earth – with whatever gear he can successfully "visualize" coming with him. This unique artifact has the potential to change a campaign in unexpected ways.
  
  
• And at the edge of the map you'll find our usual features, including a Random Thought Table to help the GM maintain the sense of awe and wonder, and Odds and Ends that shed more light on the OceanWe and the Archway.

Re: Pyramid #3/79: Space Atlas
 

Yay for Halfway to Anywhere making it in here!

Re: Pyramid #3/79: Space Atlas
 

After Warden raised that discussion about orbital mechanics, I realized how little I actually knew, and I became curious about it, for a low-key "scavengers of the Solar System" idea that's bouncing around in my head, and, tada, I now have an article about it! Hooray!

That's a lot of reading to do.

Re: Pyramid #3/79: Space Atlas
 

Pyramid: Invading your mind and stealing your thoughts since 1993.

Re: Pyramid #3/79: Space Atlas
 

You joke, but this isn't the first time I thought "You know, I really need X for my game..." only to have Pyramid publish that exact article, though usually it's Douglas Cole who writes those articles.

Re: Pyramid #3/79: Space Atlas
 

Is my brain playing tricks on me or is the Eidetic Memory column by David missing?

Re: Pyramid #3/79: Space Atlas
 

I don't think your brain is tricking you. That's odd.

Re: Pyramid #3/79: Space Atlas
 

It's just not labeled as being Eidetic Memory. Look at the first article in the issue.

Re: Pyramid #3/79: Space Atlas
 

Maybe I should have been more explicit: "Instead of an Eidetic Memory, David Pulver headlines this month's issue..."

Re: Pyramid #3/79: Space Atlas
 

It was just a curious anomaly I noticed. :-)

Re: Pyramid #3/79: Space Atlas
 

It's happened before without comment, so I didn't think it was terribly noteworthy. The most recent examples were Pyramid #3/71: Spaceships II and Pyramid #3/70: Fourth Edition Festival.

Re: Pyramid #3/79: Space Atlas
 

Whoa. I didn't notice that before either. Huh. Okay. Carry on then. :-)

Re: Pyramid #3/79: Space Atlas
 

Yeah, me either. Maybe my half-reference in the OP-description drew attention to it this time?

When a columnist has a "full" article in a given issue, we usually don't also run the column. But then again, sometimes we do -- David's done an EM and a (small) column in the same issue before. The only firm rule is that (unless he needs a month off for whatever reason) David has at least one reserved spot in each issue.

So, uh, now that this odd tangent has been thoroughly beaten to death, anyone want to talk about any of the articles? :)

Re: Pyramid #3/79: Space Atlas
 

For Halfway to Anywhere, what would the rolls for plotting all of this out be? Would players simply do the math themselves and work out the best orbit? Or if a character does that, is that navigation(Space)? And to execute the maneuver, I assume that's Pilot, but what are its rules?

I can't find any reference to navigation or pilot rules in Spaceships outside of combat. Am I missing something? Would I just use the rules in Campaigns as a basis and move on? Or is it largely unnecessary (executing a Hohmann transfer is no more complicated than putting an airplane on autopilot and going to take a nap in the Captain's chair. You only need pilot when, say, landing, taking off, or other disaster-prone points)

Re: Pyramid #3/79: Space Atlas
 

Mailanka, personally I'd figure that the point is to make is possible to calculate the minimum possible Delta V, which is a meta-meta action, a PLAYER should never have to do something like that. A common problem is characters have skill at tactics when players don't.

Sorry for being a bit muddled

Re: Pyramid #3/79: Space Atlas
 

No, it seems clear.

To me, I would expect it would be something like "We had a fuel leak after that last pirate attack. Do we still have the fuel to reach the Jovian citadel?"
"I'll do a quick calculation" says the astronavigator, and then he rolls and the GM does some fussy things with excel sheets and says
"No."
"Okay, but can I reach Ceres?" and he rolls and fails and the GM shrugs and the astronavigator takes a gamble and says "I think we can reach Ceres." and the GM works out a slightly bad path that uses more delta-v than necessary and the pilot makes a roll to execute it properly and a failure might result in some additional lost delta-v or something like that.

But I don't see any rules. Maybe my interpretation is just crazy because of reasons I hadn't considered. Or maybe there are no rules because nobody has built anything in that direction yet, and my system sounds great and, hey, when you're finished with that, if it's complex enough, it might make a great Pyramid article! Or maybe there ARE already rules, and there on pX of Spaceships and pY of Space, duh. I don't know, so I asked.

Re: Pyramid #3/79: Space Atlas
 

That sort of thing didn't really fall within the scope of the article. This article's intent was to provide tools for you to get actual answers to "How much fuel do I need?" and that's really not a GURPS rules question, hence their absence. If the remaining fuel was close to the dV requirements to reach a destination, I could see the GM requiring a Navigation roll to see if the navigator could come up with that solution - there are plenty of transfer options not covered in that article. At it's core, the usefulness of Halfway to Anywhere lies in providing minimums and maximums as guidelines for the GM to fudge his way through questions like what you asked, and for providing a range of requirements for use when designing spaceships. Planets move, and any particular alignment (especially when considering Hohmann transfers) may exist at any time, so GMs should feel free to bump dV costs up for anything but a brachistochrone transfer (that is the shortest, fastest, most dV-costly transfer possible).

Personally, I'd use Navigation (Space) to plot any courses and Pilot to execute them, like you said. I'd also allow Astronomy, Mathematics (Applied), or Physics to serve as complementary skills, and require a navigation computer (Complexity 6+) with appropriate software and orbital information for the solar system as basic tools for Navigation (Space). Time Use should be in full effect and can offset substandard computers and software. Getting that data in the first place would require Astronomy, access to a sufficiently powerful telescope or array thereof, and a days to weeks to plot the orbits of the planets observed. And still expect surprises - NASA is quite excited right now about New Horizons recently imaging the last of the five known moons of Pluto. They are curious to see if they find more in the coming two months.

As far as rules from books go, there's the Navigation Errors box in GURPS Space on p. 42 for some hints, and I'd say "time spent" is highly variable depending on the technology available. Today, it takes a couple of days for NASA to pump out optimal flight plans with a supercomputer, which is a significant and relatively recent improvement over the week or so it use to take them. At TL 10, I'd imagine that's trivial for most onboard computers. The description of Navigation (Space) really smacks of this being baseline use, too: "Navigating through ordinary interplanetary and interstellar space, usually at less than the speed of light". I don't recall seeing Spaceships cover navigation rules, though. If you really wanted to get get fancy and draw out the process in game, you could probably adapt Technical Grappling's mechanic, but you can do that with a lot of tasks...

As for article food, you know there's a Spaceships III issue on the Pyramid wishlist. Maybe something about common non-combat ship operation tasks might be fitting, if you want to write it. And if the style guide is daunting, there's a group that helps with that sort of thing...

Re: Pyramid #3/79: Space Atlas
 

That answers what I wanted to know. I wasn't asking for it to contain that, but if it did, and now I know that it does not, and that there aren't any particular details for that elsewhere, which means it's up to me to build (and I am certainly up to that task).

Thanks!

Re: Pyramid #3/79: Space Atlas
 

Anytime! I'd love to see the results in print!

Re: Pyramid #3/79: Space Atlas
 

Hey folks

I posted some extras for Skiptime, but stupidly put them in the wrong forum. Duh.

Anyway, if you wanted the Director's Cut, here it is. Mostly things that had to be edited for length, but if your characters were wondering how the OceanWe get jiggy with it... well, now you'll know.

Re: Pyramid #3/79: Space Atlas
 

So, folks... are there any comments on the issue? This was the first non-spaceship, non-Transhuman Space science-fiction issue we've done in a couple of years, and the first included spreadsheet in... wow, a lot of months. Was this issue any good? Too crunchy? Too fluffy? (I honestly like to try to give y'all what you want, if I can.) :-)

Re: Pyramid #3/79: Space Atlas
 

I'd call it inspiring. Halfway to Anywhere inspired me to work on a setting a friend of mine is calling "Echoes in the Dark." I honestly can't think of any praise higher than "It inspired a campaign," except perhaps "I'm using it right now in my rules."

I also read through Ostara and that was very... woah. I'm not sure I'd use it, but I found it a fascinating read nonetheless.

And your Random Thought Table touched on one of the reasons I find myself more and more drawn to space opera. It's not that I don't enjoy hard sci-fi (I'm totally going to see the Martian), but it's sometimes hard to explain, or grasp, some of the deeper implications of the elements that pop up in science. But Star Trek or Star Wars or their ilk, when they try, often manage to capture particular elements and make them relatable. The fact that Spock has green blood would trigger a discussion with my friends about alternate biochemistries more readily than some weird alien sponge growing out of the ground on some random world.

Re: Pyramid #3/79: Space Atlas
 

I will admit I haven't read it yet... I'm running a fantasy campaign and the space craft aren't going to show up in it until sometime next year...

Re: Pyramid #3/79: Space Atlas
 

THAT... SOUNDS... AWESOME!

(I hope we hear details at some point!)

Re: Pyramid #3/79: Space Atlas
 

It's a Gamma World by way of GURPS fantasy (so twisted/mutated by magic instead of radiation and alien tech)... in the grim far future of the shattered Earths, the many races have learned to live together and kinda share... except when they don't. The heroes are off to forge their own way in the world and eventually they'll uncover artifacts of the 'old worlds' (high and ultra tech) and may have the chance to ascend the Great Silver Tower (space elevator) that pierces the heavens and meet the GODS (totally not gods, an AI or two still eking out existence on decaying orbiters and satellites).

I've got a "and they go the Moon" segment set up if they go wildly off track...


So yes, eventually I'll read everything SPACE so I'm ready in case they decide to assault Mars or something equally far fetched.

Re: Pyramid #3/79: Space Atlas
 

My blog review. Short summary: makes me want to run another space game.

Re: Pyramid #3/79: Space Atlas
 

My blog review. Short summary: makes me want to run another space game.

Re: Pyramid #3/79: Space Atlas
 

Don't be surprised if you get this reaction from the PCs when they reach the moon (Mild Language Warning):
https://youtu.be/GUEVyvwwNhY?t=243

Re: Pyramid #3/79: Space Atlas
 

Wow, thank you, Mailanka! If you have any questions, post them or PM me and I'll respond as quickly as possible.

I'm biased and won't give my opinion of Halfway to Anywhere. I will say that usually this sort of "fluffy" issue usually doesn't appeal to me because I prefer to create my own campaign content, but once in a while these sorts of articles will be packed with cool ideas and nuggets that inspire me to create loxations, tech, cultural characteristics, etc. Ostara and OceanWe both do this handily and are already creaping into new content for my scifi setting. CR Rice's The Vanishing Sun would fit right at home in an episode of Star Trek or can serve as an entire campaign setting on its own, and Steven's Homeward Unbound is brilliantly inspiring as new tech, an alien mystery, and just interesting as a campaign assumption. Even if I hadnt recieved a comp copy, Id have bought it.

Frankly, we need more scifi issues! I'm quite happy to see some interesting edgings in that direction on the wishlist :)

Re: Pyramid #3/79: Space Atlas
 

Thank you so much for the comments and reviews, folks! I appreciate it.

The science-fiction issues have generally been softer sellers than non-SF issues (which is one reason we don't do more of them). I'm curious as to why, and if there's anything I can do to the Pyramid mix or focus that would make them more popular. Hence my probing questions. :-)

Re: Pyramid #3/79: Space Atlas
 

I do not know what scifi issues have sold well and what have not, but a some of the scifi issues you have been too "fluffy" for me. That was specially true for the early issues. (Scifi tricorder toy... ugh)

I do not claim to be a typical gamer, as I am in the small segment of people who actually liked 3rd ed Vehicles (and in fact it was eventually the reason I started playing GURPS), so for more generic gamers things may be different. But I would think that a lot of the people who enjoy running/playing scifi games are more on the details side of the spectrum as compared to something like dungeon fantasy or action though I may be outside the norm even for such.

The best "scifi" issues you have had for me are the tech and toys,spaceships,military scifi ones. (several useful things in each)

The aliens, space exploration,second transhuman space and space atlas are kind of medium(one very useful article, some other maybe useful)

The useless ones are space colony alpha, space opera and the first transhuman space issue where I did not see anything useful for me.

I do not know what else you consider scifi so cannot comment on them.

Re: Pyramid #3/79: Space Atlas
 

I suspect the problem with sci-fi is that it's much more diverse than fantasy (it doesn't have to be, of course, but "Elves, dwarves and humans go fight orcs and skeletons and dragons in a dungeon" is ridiculously popular). But ask people what they want out of their sci-fi, and one guy wants space-knights and force swords, and another guy wants phasers and tricorders (I liked the space opera scanner!) and yet another guy wants gloomy soldiers fighting scary bugs, and yet another guy wants Neil deGrass Tyson narrating his diamond-hard exploration of space physics with the occassional (physically accurate!) gun battle, sprinkled with Atomic Rocketship-style introspection on space economics (and that's all just space! We're not even touching on Gattaca, Blade Runner, Neuromancer, Robocop, etc). All great games, much harder to serve than "Look, here's more monsters for your elves, dwarves and humans to kill."

Re: Pyramid #3/79: Space Atlas
 

Personally, I can say I generally flock to anything that looks like scifi, but I generally am less excited about "fluff" pieces overall. With scifi, I find fluff pieces particularly susceptible to "I'm not running that so why would I want it" syndrome.

Crunchy articles get most of my attention, since crunch generally translates across genres and subgenres. I may not need a scifi organization dedicated to the psychic hunting of transhuman cybernetic space werebats, but I probably wouldn't mind some more rules concerning cybernetics, transhumanism, or psychic powers and technology (provided they don't already exist, of course!). The latter I can adapt to my own games or settings.

While it might be hit and miss (for apparent reasons), I could see more targeted scifi issues the likes of Cyberpunk, Golden Age Scifi (Atomic Rockets and Ray Guns), Hard Science Fiction, Military Scifi, Near Future Scifi, Planetary Romance, Space Opera, Transhumanism, etc. I know some of these have been covered already, and I'm not entirely certain which ones would sell best. But I think this might provide more utility to consumers, since I can pick up the Gothic Space Opera issue if that's what I was running. But again, I'd want more crunch that I can potentially port over to other genres, frex, if I am running a pulpy gothic space opera, I might enjoy an article in Planetary Romance about making swords and blasters coexist peacefully so my players can run over-the-top military types who can be reasonably effective charging a tank with a saber or with a laser gun.

Subgenre specialization aside, gear indices are nice, but more useful are articles that tackle potential loadouts with gear expantions incorporated. UT's downfall, imo, is the hodgepodginess of it all. It takes a ton of GM work to sort out what's available and tons more to sort out how they interact and would see service. Articles to that end would probably be quite useful - something akin to the article on modern military loadouts (I can't remember the title or issue; will replace when found).

Lastly, I love articles that let me build things myself. I might like a treatise on artillery-scale ultratech weapons, but I would REALLY like to have rules for making my own ultratech artillery! I like seeing creative Spaceships builds, but I LOVE getting my fingers on things like Alternate Spaceships and new systems. Basically, I prefer rules and tools to fluff. As a GM, I don't mind doing the legwork myself. I'm probably in the minority in that respect.

Re: Pyramid #3/79: Space Atlas
 

One other thing that might be interesting to help focus "scifi" into something more useful for GMs might be breaking down issues by TL - Cutting Edge already seems to be experimenting with that. I could see this as helping collect a group of gear that might interact and giving a rule structure for handling it all together.

Re: Pyramid #3/79: Space Atlas
 

At the danger of me too-ing this.... me too.
I love organizational details and rules "crunch".

Re: Pyramid #3/79: Space Atlas
 

I don't have any problems with this issue, though I didn't see anything that jumped out as being particularly useful for me; if I were to ever do a hard-science UT campaign featuring in-system space travel heavily I'd probably use the travel article, but none of the others say 'use me' all that much - and I like UT. I just don't find settings all that useful, personally - especially settings that are all fluff with no crunch.

A setting coupled with a GURPS Action equivalent tailor-made for the setting and genre? That's something I could get behind. Just fluff coupled with maybe four 'monster'/alien stat-blocks? Not so much.

Aren't setting-heavy issues generally low-sellers already, not just when coupled with UT?

Things I'd like to see in an Ultra-Tech-based Pyramid article:

• Revised UT weapons and armor, either to fit better with HT equivalents or to fit better with 'DF in SPAAAAAAACE' campaigns.
• Expanded/alternate UT computer use and hacking rules
• Expanded/alternate cybernetics or bioengineering rules
• Expanded/alternate rules for lockpicking/trap disarming/etc in an Ultra-Tech setting
• Custom design UT tech rules, like robots, AIs, guns, power armor, vehicles, etc
• Expanded/alternate gadgeteering rules
• Monster bestiaries for mutated or alien enemies
• Generic Ultra-Tech henchmen formatted like a monster bestiary entry

For each of these things, they don't need to be completely generic - detailing stuff like this with a single setting's assumptions in mind is fine so long as those setting assumptions are mentioned.

This list is largely 'stuff I would have found useful in setting up Edgerunners'; as-is, I actually wrote the first five of the entries in that list for that campaign (and my players wrote some of the rest), so it's stuff that, to me, would have been great (and in some cases was great, as I used as inspiration a good bit of stuff from some of the other Pyramid UT articles such as Cyberspace Cowboys and The Thinking Machine or whatever their names were). It's also all heavily crunch.

One thing that could be interesting is an 'assumed setting' found in multiple Pyramid articles EDIT: in multiple issues. Each article might be useful on its own, but when combined with others specifically designed to be in the same setting together it could become Voltron or Captain Planet or Devestator or any of the other 'By Our Powers Combined' trope-holders.

Re: Pyramid #3/79: Space Atlas
 

On the astrophysical side, I'd buy a reworked planetary system constructor kit - one that allows editing multiple individual planets in the solar system even after being generated randomly, and preferably one where the Excel format is merely the output or storage format, and isn't involved in formula-checking and random-creation procedures. But I do realise that this is not what Pyramid articles are like, the recent Halfway to Anywhere notwithstanding.

Re: Pyramid #3/79: Space Atlas
 

"If I were to write another planet write-up with bizarre society, like my piece Nahal in the 27 March '08 issue of Pyramid 2, would that be well received?

How about an essay on the physics of tides and tidal braking? Or an essay on surface conditions on spin:orbit resonant worlds?"

Very much yes please to all of them.

Re: Pyramid #3/79: Space Atlas
 

For me, the lattermost would be extremely useful. The second to last would be merely interseting but probably have no bearing on any game I'd run (and I'm a hard scifi kind of guy), and the first I'd have no interest in. Expanding away from rules and just generally useful info pertinent to scifi gaming (a category I totally forgot to include in my list of stuff above! good catch!), I'd love to see topics like extrasolar planet weather, the aforementioned surface conditions of tidally locked worlds, effects of orbiting a binary star (on stuff like day length, climate, weather patterns, etc.), estimating the strength of radiation belts around planets (even though this may boil down to pure GM arbitration based on what we know of our own solar system), at what orbital radii various minerals are likely to occur, or anything else that helps me create and describe an alien world as more than "Earth but with a reddish sky". The implications of all of those things are what drive interesting colonies and cultures to me. What if orbiting a binary can result in more than 4 seasons? What if the alternating tug of multiple stars causes the planet to tumble unpredictably, so that the day length changes randomly and constantly? What if the orbit itself is jerked all around so that seasonal changes are not regular? What if the primary star is brightest in the reds and infrareds and emits little blue, violet, or UV radiation - how does that affect plant growth? These would all not only help me destribe worlds in more better and more interesting detail, but it would also spark a lot of "what if" questions that are the bread and butter of ANY scifi genre. In my experience, the possibilities presented by the real world far exceed even the best and most creative authors in their ability to astound and captivate the imagination.

Re: Pyramid #3/79: Space Atlas
 

I am probably a bit unusual but my three most used pyramid issues have been the Aliens, Space exploration and Space Colony Alpha issues mostly because of some of the 'background' articles.

Things like 'Making Something Alien' and 'How to Build Tomorrow' have changed the way I think about parts of my settings and the way I use existing elements of the rules. More of this sort of thing would be useful, I can certainly see scope for similar exercises looking at tailoring star ships to particular campaign needs and would definitely second the suggestion on planetary environments.

Also while I would second the call for less fluff, or at least more targeted fluff I would be slightly concerned if this was just setting fluff plus mook/ beastie/ ship stats shoehorned in at the end. I think that the cure to this would be to have an implied setting in these articles, actually I think that you would need two* to offer better coverage of a wider range of options. In addition to this I would also keep things topic based 'looting your lifepod's locker' in the space exploration issue is probably still my favourite crunch article (despite being somewhat narrow) probably because it combines a specific topic with a variety of variations.

*Probably one higher TL, high superscience setting and a smaller scale harder, but not hard, science setting. Hard science single system stuff is already covered by Transhuman Space.

Re: Pyramid #3/79: Space Atlas
 

When I saw the title “Space Atlas” for this issue, I was sort of expecting at least one space map for an interstellar neighborhood (or at least a star system). The closest we got was the Diagram of Bi-Elliptic Transfers on page 27. <sigh> Of the articles, Halfway to Anywhere was my favorite. I’ve always been a bit of a math geek, so any time I get a list of equations I’m very happy. I was a bit surprised that that you included the equations for Bi-Elliptic Orbits (btw. these do “suffer launch window restrictions” unless you plan to loiter at transfer orbit apoapsis by splitting the second burn to achieve a temporary circular orbit) but not those for One Tangent Burns that can be used for Free Return trajectories. While minimizing ΔV is important for unmanned missions, minimizing TOF (Time of Flight) may be more important for manned ones. BTW, the spreadsheet needs a bit of work; you've got the article title wrong on each sheet. ;)

Re: Pyramid #3/79: Space Atlas
 

Thanks for pointing that out! I've patched it up.

Re: Pyramid #3/79: Space Atlas
 

Specific bi-elliptic orbits suffer launch window reatrictions, but you can change that window by altering the length of the semi-major axes of the transfer orbits [a(c) iirc; idhmbwm]. The article does sacrifice detail - e.g., which a(c) will let you launch now with minimum time of flight in exchange for not tackling some nasty calculus. But its safe to say that by manipulating a(c), a navigator can manipulate the necessary launch window for a bi elliptic transfer without circularizing the orbit and loitering.

Re: Pyramid #3/79: Space Atlas
 

Great, where can I get a copy?

To continue the errata, in the “Formulae by the Numbers” sidebar on p.29,

1. the first “Achieving Orbit” equation has a few problems;
   1. the last part should be [1 + S/(A-S)] (actually [A/(A-S)] would be simpler).
   2. no allowance is made for atmospheric drag here.
   3. Should "winged lift" reduce gravitational drag?
2. the first two “Oberth Effect” equations use V(per) instead of V(esc) as in the text.
3. the second term of the Brachistochrone Transfers ΔV equation does not match the ones in the preceding main text or the “Index of Formulae” sidebar. Which one is correct?

Also, on page 27 you state “the total delta-V of fuel needed equals the absolute value of ΔV1 plus the absolute value of ΔV2.” While technically accurate, in a Hohmann Transfer both burns are either prograde or retrograde and will thus have the same sign, making “the absolute value of (ΔV1 + ΔV2)” equally true.

PS. I'm confused about this paragraph: Both? Really? How does that work? Also, just to clarify terms: when breaking a planetary orbit to enter a solar transfer one, is the final velocity relative to the planet the transfer ΔV relative to the star?

Re: Pyramid #3/79: Space Atlas
 

A suggestion for the “Halfway to Anywhere” spreadsheet: see my thread FWIW: A Significant Formula for GURPS Spreadsheets for a formula you can use to round the raw value of calculations to 2 significant digits.
PS. Where can I can the updated version of the spreadsheet? Do I have to D/L the Pyramid issue again?

Re: Pyramid #3/79: Space Atlas
 

Just re-download the issue.

Re: Pyramid #3/79: Space Atlas
 

Okay. Is this change to the enclosed spreadsheet enough to generate an issue update notification? Have the errata I've mentioned above been addressed?

Re: Pyramid #3/79: Space Atlas
 

In the latest “Halfway to Anywhere” spreadsheet, the formula for Transfer Duration: of “Brachistochrone Transfer” is:
In order to match the equation on page 29, it should be:
Note the position of the second F11. This causes a significant difference in the result at very low accelerations. Which one is in error?

Re: Pyramid #3/79: Space Atlas
 

Thanks for your efforts!

When the issue and/or spreadsheet are significantly updated, I'll let folks know. (I didn't send an email update when was the wrong title on the spreadsheet, because that was a minor issue.)

Re: Pyramid #3/79: Space Atlas
 

I have just moved, so it will take me a few days to adress these properly. I will look into them, though.

Re: Pyramid #3/79: Space Atlas
 

I was a little confused about the way the thrust requirements for a winged takeoff to orbit is supposed to work on page 26. It suggests that a thrust of 1/5 * atmospheric pressure * local gravity is required, which from what I can understand means that essentially the lift from the wings is reducing the requirement, but by that formula it seems to be saying that a higher atmospheric pressure means it requires a higher thrust (and indeed that above 5atm, a winged vehicle would require more thrust than a 'straight-up' rocket launch).

Am I misinterpreting something or is this actually correct? It seems counter-intuitive to me.

Re: Pyramid #3/79: Space Atlas
 

Atmospheric drag increases proportionally with atmospheric density. GURPS makes a habit of subbing pressure for density, presumably because it is relatively close, and more importantly, its more easily calculated and measured. And since lift generated by a wing is proportional to airspeed, lift is proportional to atmospheric pressure. That entire thing is a bit of an approximation of a fairly complicated mess of physics borne out by data from lifting body performances.

Remember that this is just about the amount of thrust needed to take off, not how much Dv is required to reach orbit - I specifically didnt venture into that quagmire (giggity) because there are just too many variables.

Also, remember that thrust is not change in velocity (Dv) Thrust is a force. Wings generally allow you to convert some horizontal thrust i to vertical lift. The rocket you mention would be spending all of its fuel just lushing down and not forward or upward. I'm sure there is a break even point somewhere, but yiud need to go somewhere like Venus or Jupiter to experience it.

Re: Pyramid #3/79: Space Atlas
 

I thought the calculations for deltas and stuff for liftoff are already shown on Spaceships 1 p. 37?
Anyway, the 1/5 × Density × G requirement seems to disregard the fact that craft with lesser acceleration seem able to lift off the ground, and the higher one goes, the lower atmospheric density.

Re: Pyramid #3/79: Space Atlas
 

I think this is the bit that's still throwing me a bit for a loop. :) Bear with me while I give a (hopefully) more coherent example of what I mean (and most likely what I'm messing up here):

Say you have a vessel with a thrust of 0.15G and an available dV of 96mps (eg, 3 x TL10 Fusion Pulse Drives and 8 x Fuel Tanks using the rules, including the dV increase from GURPS Spaceships p. 17) and you've given it a streamlined hull and wings. And let's also ignore for a moment how annoyed people are probably going to be that you're setting off a chain of nuclear explosions in their atmosphere. :)

So here's the part where I get confused... If you're on a planet with a surface gravity of 1G and an atmospheric pressure of 1 atm, this means the minimum thrust you'd need to be able to reach orbit using the calculations on p. 26 of the Pyramid issue is 0.2G - in other words, this ship isn't going anywhere. However, if a catastrophe occurs and the Spaceballs come along and suck off a bunch of our atmosphere to sell as canned air and the atmospheric pressure ends up dropped to 0.5atm, that means we'd only need a thrust of 0.1G and now we can get into orbit, despite the fact that the atmosphere is half as thick so we're only able to generate half the lift from it. This seems to continue down until you get to a trace atmosphere, and an aerosol spray can (or a cargo hold full of them at any rate) will be enough to get you to orbit, as long as you can meet the dV requirements (which would probably be difficult with spray cans, but the 96mps dV the example above has would be plenty).

Does that make any sense? I'm probably missing something but it still seems to be suggesting that the less atmosphere you have, the less thrust you need to be able to produce to get to orbit (assuming you have enough dV available of course). I know the space planes NASA's been designing for Mars have to maintain a much higher speed just to remain aloft compared to planes on earth, etc.

Sorry for the rambly post. I promise I'll shut up after this. :)

Re: Pyramid #3/79: Space Atlas
 

The less atmosphere there is, the less atmosohere there is, the less drag you encounter. This lets you move faster. Lift gets bigger as you move faster, and more winglift means less acceleration needed. So as long as you can stay aloft (Spaceships, p. 40 requires an atmosphere thats at least Very Thin for this), thinner means faster means more lift.

In your example, halving pressure halves drag, which means half as much force is fighting your thrust. That means you achive higher speeds, which is squared to determine lift. More lift means your engines dont have to push against gravity as much...which lets them push forward for more speed, which gets squared... There are diminishing returns that result in a max airspeed, but less atmosphere means faster airspeed, which means more lift.

I'm setting up a model in excel and will update this post with more explaination in a few minutes.

Re: Pyramid #3/79: Space Atlas
 

Ahaaaa I get it now... ugh, and feel dumb. The part that I was missing was that with the reduced friction, your thrust was actually providing better performance. Sorry to have dragged that out so much, but thanks very much for the responses... I'd certainly still be scratching my head otherwise. :)

Re: Pyramid #3/79: Space Atlas
 

Any time! I find playing with actual drag and lift formulas, results are all over the freaking place. I think the formula in the article should suffice without actually designing a spaceplane. There are a lot of things that seem to affect performance.

Re: Pyramid #3/79: Space Atlas
 

I'm finally settled enough to dig into these concerns properly, and some of these are valid. I am replying on a phone, since I'm still waiting for AT&T to hook up my internet, so please bare with poor formating and typing.

Correct, and the simplification is probably easier to use. I didnt do too much to reduce things down in order to reduce mistakes on my part.
This was an oversite from when I copied all my raw formulas into the box (atmosoheric drag got added in editing). A final term reading "+ 0.01588 x P(atm)" should be added there. P is measured in Pascals and the crazy factor is a conversion, so it shouldnt be subject to significant figures, ideally (1609.34/101325). I riunded to 5 sigfigs here. I'm not sure how many Steven would want to round to.
Ugh, more wing questions! Lol. Ok, so the Achieving Orbit equations are for rockets. Space planes are planes and god knows what their dv requirements would be. Thats totally an aeronautical engineering thing, and i'm not qualified to answer that. Its also a different article, so to answer your question, if a space plane takes offnlike a rocket, wings wont do much. If it takes off like a plane, they do stuff that is beyond my ability to provide detailed gurps rules for.

The one in the text is correct.

True but that doesnt affect the veracity of the equation.


Sigh. I spend an hour going over this again and found where I'm pretty sure I have made a bit of an error here.

V(esc) and V(per) are both suppose to be escape velocity at closest approach (periapsis). You still use the formula Escape Velocity (p. 26) to calculate this, but you dont need to know your velocity at periapsis (vi if you are in orbit), really, since this article assumes you have a circular orbit. Instead, vi is just your orbital velocity.

When breaking orbit, vf gets replaced with v(per), making the first term sqrt(2*v(per)^2). Vi becomes your orbital velocity, which i suppose i need to provide an equation for.

To avoid confusion, i'd make all V(esc) in Coasting into V(per) to represent the more specific "escape velocity at closest approach".

Re: Pyramid #3/79: Space Atlas
 

This is something I can implement if Steven wants. I prefer a slightly different formula than yours, but it gives the same results.

Would it be more helpful to have a global sigfig setting or one for each page?

Re: Pyramid #3/79: Space Atlas
 

The spreadsheet should match the article. I'll update this even if sigfigs dont get implemented. Nice catch.

Re: Pyramid #3/79: Space Atlas
 

Hey, all!

As an update: I've just pushed an update to this issue. It has some updates to the "Halfway to Anywhere" article, plus some tweaks to the spreadsheet.

If you have a Warehouse 23 account and subscribed to or bought that issue, you should've already gotten a notification by email. But just in case... feel free to swing by your Warehouse 23 library and redownload it!

Re: Pyramid #3/79: Space Atlas
 

Great, and thanks!

I finally bought this a few days ago. Halfway to anywhere was what drew me in, but I haven't even read it yet, having been drawn in by Ostara. Great setting, and another big win for David Pulver. Normally I'm a crunch kind of guy, but now I'm itching to read the other settings in the issue.

Though I'm already plagued by a few head-scratchers about how the hives would work long-term.

Re: Pyramid #3/79: Space Atlas
 

I have a small issue with the “Achieving Orbit” equation in the “Formulae by the Numbers” sidebar. It should be made clear that P is atmospheric drag expressed in mps/Atm of atmospheric pressure. Also, shouldn’t streamlining have some effect on this factor? (That is, by dividing the drag by 5 for streamlined ships?)

Re: Pyramid #3/79: Space Atlas
 

Great title! I heard of it when reading an article by Isaac Asimov about a discussion he had had with Robert Heinlein, discussing Heinlein's then-upcoming story “the Man Who Sold the Moon” (a story about the challenges to be faced in reaching the moon), and a difficulty an earlier story he had written was causing him: in that earlier story, he had established the ability to achieve Earth orbit with little trouble; Asimov said something like “Oh, I see; once you're in Earth Orbit, you're halfway to the moon”, and Heinlein responded “no; once you're in Earth Orbit, you're halfway to anywhere!”

Re: Pyramid #3/79: Space Atlas
 

~puts his shovel away~

Just thought I'd try to breathe a touch of life back into this again.

I have recently launched my first rocket (IRL) and thought I'd share the results, so people might learn from my own experience.

Despite a rather tumultuous design and fabrication experience, we did lift off on time and achieve roughly average apogee despite it being generally about 10% lower than the ideal predicted height. We are chalking this up to a mix of random variables (it was windy and we had to launch at an angle into the wind so we had a chance of recovering our rocket, plus random added weight in the form of unexpected tape, glue, paint, fillets, etc.; plus just the randomness inherent to models vs. reality.) So, if you are using Halfway to Anywhere, I'd suggest that it is a best case scenario, and GMs who want things to go wrong (or players who want to design for the unexpected) should consider a 10% difference in performance from the calculations - and not in your favor.

All of that said, the GM should never be afraid to fudge in the favor of plot. After all, Armageddon wouldn't have been a very enjoyable movie if Bruce Willis et al died on launch....

A full review of the design, launch, and results experience will be posted on my blog this week. See my signature for details.

Re: Pyramid #3/79: Space Atlas
 

I've wanted to use your Halfway to Anywhere rules for awhile, and I will, once I start my work on Echoes in the Dark, and I've actually been struggling with exactly that: What do you do on a miss? Of course, you might get lost, and getting lost in the Solar System might be bad (as in lethally campaign-ending). A 10% loss on Delta-V might be okay, but it varies between no big deal and lethally campaign ending. If you're going to have Navigation rolls, failures should have interesting consequences, rather than spell a big game over, or a minor inconvenience.

Re: Pyramid #3/79: Space Atlas
 

This I totally understand. Halfway to Anywhere was originally developed so I knew how much dV to assign to spaceships I designed. It grew from there, but frankly, screwing up a Navigation roll in a hard sci-fi game should be dire. I know that isn't fun, which is why I generally wouldn't count that against a PC or expect a PC to make that roll. Of course, that doesn't fit everyone's games.

I think if I were requiring Navigation rolls for plotting orbital transfers, I'd make a failure result in using up 10% more fuel or using up all remaining fuel, whichever is less dire. Frex, if you botch a Nav roll to get to Mars, at the least, you'll get to Mars, but you might not have fuel to get back to Earth, which provides an adventure hook. If you aim for the moon, with dV to spare, you might lose profits because you burn extra fuel on a failure. Regardless, on a crit fail, you should probably be in deep trouble, as determined by the GM (start making Mechanic or Engineering rolls to pull an Apolo 13 out of your butt).

But again, this is really up to the GM. Halfway is meant as a guideline for GMs so they have bounds one what to expect of PCs' spaceships.

Re: Pyramid #3/79: Space Atlas
 

That's some pretty good advice there. I'll bookmark that post for when I get back to working on that campaign.