Pioneer - Get Ready for Launch!

[rinku]

Back on topic...

It would be neat if they can boil real world orbital mechanics into a reasonable set of tables or rules, similar to how CRB uses expended Thrust and 6 minute space combat rounds to change range bands. Anything that is devised for Pioneer will be usable in regular Traveller or 2300AD.

 

[Sigtrygg]

All you need is a delta V chart,

Delta-v budget - Wikipedia

en.wikipedia.org

or you can do it the hard way:

Missions - Atomic Rockets

www.projectrho.com

 

[paltrysum]

All you need is a delta V chart

Precisely!

 

[rinku]

Yeah, that was the sort of thing I was thinking of.

 

[Reynard]

I must say, I am intrigued. First saw the big splash PIONEER and thought some sort of exploratory source book then read the description and you got my attention. I've had several gos at designing a somewhat realistic near future what if at the dawn when humanity develop a working non-reaction drive system making our solar system feasibly accessible and all the ramifications of highly compressed time and space scales that brings.

Do continue.

 

[rinku]

In terms of compressed time, Traveller already sits well. The experience progression system is based on months and years of training, and while the action can take place over short periods of time, jump travel is slow in human terms and it caters for long cycle events such as ageing. Going to "it takes six months to transfer to Mars, we'll not game that out in detail for this campaign, just make a few event rolls" isn't much different to "10 jumps to get to Glisten, just make the jump rolls and a few event rolls".

 

[Michael S]

In terms of compressed time, Traveller already sits well. The experience progression system is based on months and years of training, and while the action can take place over short periods of time, jump travel is slow in human terms and it caters for long cycle events such as ageing. Going to "it takes six months to transfer to Mars, we'll not game that out in detail for this campaign, just make a few event rolls" isn't much different to "10 jumps to get to Glisten, just make the jump rolls and a few event rolls".

Those 4-7 month travel times are perfect for the "Murder on the Martian Express" scenarios, And those transfers could be run as convoys with smaller ship to ship transfers and intrigue during the trip too.

 

[robertsconley]

All you need is a delta V chart,

Exactly, the High Frontier Boardgame has a map of the Solar System that is basically an energy map.

I've been working on my own version off and on for a number of years.

---

So nodes and junctions represent spots where burns can take place where each burn is roughly 2.5 km/s of Delta Vee.

For the Expanse and its use of the Epstein Drive, I came up with the following chart to figure out travel time using the map.

• .3 G = 2 days per burn
• 1 G = 1 day per burn
• 7 G = 1/3 day per burn
• 12 G = 1/4 day per burn

The whole point of using the map is to allow the players to change direction if they get a message or something that causes them to change their mind about where they are going. The Expanse novels depict a number of different accelerations that were used. I picked the four most commonly mentioned and calculated those values. The result is not exact but close enough for an RPG campaign.

For chemical rockets the ballpark travel time is to look up the orbital period of the target i.e. the time it takes to travel around the sun. And take half of that as your travel time. While the Epstein drives have limited fuel (20,000 ms/) total delta-vee of chemical rockets is considerably less so the number of 2.5 km/s burns you have to do has to be tracked.

The final point of this to eliminate having to do any math in play. Just use the map, and use either the acceleration for traveller or expanse style ship, or the fuel quantity rated in delta vee.

Oh if you want to intercept something using the map. You have to arrive at the same junction or node at the same time. If you are traveling along the same path, then you will have multiple rounds of combat. If you are both on intersecting paths, you get one round, and that is it.

 

[MasterGwydion]

Exactly, the High Frontier Boardgame has a map of the Solar System that is basically an energy map.

I've been working on my own version off and on for a number of years.

View attachment 6209

---

So nodes and junctions represent spots where burns can take place where each burn is roughly 2.5 km/s of Delta Vee.

For the Expanse and its use of the Epstein Drive, I came up with the following chart to figure out travel time using the map.

• .3 G = 2 days per burn
• 1 G = 1 day per burn
• 7 G = 1/3 day per burn
• 12 G = 1/4 day per burn

The whole point of using the map is to allow the players to change direction if they get a message or something that causes them to change their mind about where they are going. The Expanse novels depict a number of different accelerations that were used. I picked the four most commonly mentioned and calculated those values. The result is not exact but close enough for an RPG campaign.

For chemical rockets the ballpark travel time is to look up the orbital period of the target i.e. the time it takes to travel around the sun. And take half of that as your travel time. While the Epstein drives have limited fuel (20,000 ms/) total delta-vee of chemical rockets is considerably less so the number of 2.5 km/s burns you have to do has to be tracked.

The final point of this to eliminate having to do any math in play. Just use the map, and use either the acceleration for traveller or expanse style ship, or the fuel quantity rated in delta vee.

Oh if you want to intercept something using the map. You have to arrive at the same junction or node at the same time. If you are traveling along the same path, then you will have multiple rounds of combat. If you are both on intersecting paths, you get one round, and that is it.

That looks like a lot of work! Nice job!

 

[robertsconley]

Back on topic...

It would be neat if they can boil real world orbital mechanics into a reasonable set of tables or rules, similar to how CRB uses expended Thrust and 6 minute space combat rounds to change range bands. Anything that is devised for Pioneer will be usable in regular Traveller or 2300AD.

So the thing to keep in mind with orbital mechanics is that it’s not going to be a Star Fleet Battles–style hex grid, nor will it resemble classic Traveller, Triplanetary, or other vector-based systems, or even range-band combat.

The issue is that the gravity of the body you’re orbiting dominates everything. Even with an Expanse-style or Traveller-style continuous-thrust drive, you’re not limited by delta-v so much as by time, the time required to shift your orbital parameters enough to intercept a target.

There are some basic things to remember about motion in orbit:

• The closer you are to the planet, the faster you move around it relative to objects in higher orbits.
• The energy required to raise or lower your altitude is about ten times smaller than what’s needed to shift the plane of your orbit.
• Even if you have the energy for a plane change, the locations where those shifts can occur are fixed for a given orbit. You’ll have to wait, or spend a lot more energy to force the maneuver sooner.
• If you’re not in the same orbital plane and direction as your target, you’ll have only a fleeting window of opportunity to take your shot, basically a round or two.

Based on my experience writing historical spacecraft add-ons for Orbiter Space Simulator, space combat is more about analysis and strategy than piloting. It’s about crafting a maneuver plan, executed at the right time, with precise burns in the right order, while outthinking your opponent to create that brief window to take a shot.

 

[Sigtrygg]

Exactly, the High Frontier Boardgame has a map of the Solar System that is basically an energy map.

I've been working on my own version off and on for a number of years.

View attachment 6209

---

So nodes and junctions represent spots where burns can take place where each burn is roughly 2.5 km/s of Delta Vee.

For the Expanse and its use of the Epstein Drive, I came up with the following chart to figure out travel time using the map.

• .3 G = 2 days per burn
• 1 G = 1 day per burn
• 7 G = 1/3 day per burn
• 12 G = 1/4 day per burn

The whole point of using the map is to allow the players to change direction if they get a message or something that causes them to change their mind about where they are going. The Expanse novels depict a number of different accelerations that were used. I picked the four most commonly mentioned and calculated those values. The result is not exact but close enough for an RPG campaign.

For chemical rockets the ballpark travel time is to look up the orbital period of the target i.e. the time it takes to travel around the sun. And take half of that as your travel time. While the Epstein drives have limited fuel (20,000 ms/) total delta-vee of chemical rockets is considerably less so the number of 2.5 km/s burns you have to do has to be tracked.

The final point of this to eliminate having to do any math in play. Just use the map, and use either the acceleration for traveller or expanse style ship, or the fuel quantity rated in delta vee.

Oh if you want to intercept something using the map. You have to arrive at the same junction or node at the same time. If you are traveling along the same path, then you will have multiple rounds of combat. If you are both on intersecting paths, you get one round, and that is it.

That is a thing of beauty

 

[Sigtrygg]

Ever see the SPI game Battlefleet Mars?

 

[Anstett]

The issue is that the gravity of the body you’re orbiting dominates everything. Even with an Expanse-style or Traveller-style continuous-thrust drive, you’re not limited by delta-v so much as by time, the time required to shift your orbital parameters enough to intercept a target.

Based on my experience writing historical spacecraft add-ons for Orbiter Space Simulator, space combat is more about analysis and strategy than piloting. It’s about crafting a maneuver plan, executed at the right time, with precise burns in the right order, while outthinking your opponent to create that brief window to take a shot.

Leading back to why Astrogation is a key skill to have on board your ship. It directly mentions in system navigation as part of that skill.

 

[Vormaerin]

Leading back to why Astrogation is a key skill to have on board your ship. It directly mentions in system navigation as part of that skill.

Yup. Unfortunately, there's no support for actually using it for that. It would be super nice if there was information on what you could do with astrogation for the large share of players who are not astrophysicists or the equivalent.

 

[MasterGwydion]

Yup. Unfortunately, there's no support for actually using it for that. It would be super nice if there was information on what you could do with astrogation for the large share of players who are not astrophysicists or the equivalent.

Why not just make it a 5% reduction in travel time for each point of success? Also, a 5% increase in travel time for each point of failure.

That should be simple enough for anyone to use when combined with the awesome thing that @robertsconley built.

 

[CordwainerFish]

the large share of players who are not astrophysicists or the equivalent

[citation needed]

 

[rinku]

I got my head around the basics of orbital mechanics from Tom Wolfe's The Right Stuff. Reccommended as a very easily digestible primer to real life space stuff. As well as a damn good book. Gravity and The Martian are rightly cited as inspirations for Pioneer, but read this one too. The movie is good as well, but necessarily leaves out a lot of the technical stuff.

The basics of astronomy are also pretty easy to pick up. NASA is a good resource.

 

[CordwainerFish]

I learned young what a Hohmann transfer orbit was, from Heinlein. The Rolling Stones even has an Oberth maneuver.

Really, once you know that orbits are ellipses you're halfway to anywhere.

 

[robertsconley]

Why not just make it a 5% reduction in travel time for each point of success? Also, a 5% increase in travel time for each point of failure.

That should be simple enough for anyone to use when combined with the awesome thing that @robertsconley built.

You actually have two cases to account for: continuous thrust, like with an ion drive, and traditional maneuvers using chemical rockets, where you burn specific amounts of delta-v at specific times.

In either case, any maneuver plan is going to have built-in leeway to account for the fact that not everything goes perfectly. You’ll need to make course corrections later in the maneuver. Because of that, the maximum improvement is going to be modest, margins are already tight to begin with.

For continuous thrust, this leeway would show up as a small reduction in travel time, 1% to 5% seems reasonable.

For delta-v-based plans, I’d suggest a 1–5% reduction in fuel used instead. The trajectory’s travel time will mostly depend on the timing of the maneuver window, so it won’t change much. The leeway instead manifests as fuel (delta-v) that can be applied to a later maneuver.

Also, thanks for the compliment!

 

[MasterGwydion]

You actually have two cases to account for: continuous thrust, like with an ion drive, and traditional maneuvers using chemical rockets, where you burn specific amounts of delta-v at specific times.

In either case, any maneuver plan is going to have built-in leeway to account for the fact that not everything goes perfectly. You’ll need to make course corrections later in the maneuver. Because of that, the maximum improvement is going to be modest, margins are already tight to begin with.

For continuous thrust, this leeway would show up as a small reduction in travel time, 1% to 5% seems reasonable.

For delta-v-based plans, I’d suggest a 1–5% reduction in fuel used instead. The trajectory’s travel time will mostly depend on the timing of the maneuver window, so it won’t change much. The leeway instead manifests as fuel (delta-v) that can be applied to a later maneuver.

I just tossed out some random numbers. Good that someone with better knowledge than I can suggest better numbers.

Also, thanks for the compliment!

People should always be praised for doing better than I can do.