CT Only: The overwhelming utility of grav vehicles

[Tobias]

I've been thinking a bit IMTU on how grav vehicles should work in CT and how they should compare to other types of vehicles.

CT canon is generally that grav vehicles start being ubiquitous at TL 10. All grav vehicles are effectively orbital spacecraft (including the humble Air/Raft), making other forms of vehicles generally However, according to Book 4, grav vehicles only gradually gain these capabilities over TLs 9-13. However, this is not supported by design rules from Striker onwards, which again give fusion-powered grav vehicles their full potential at TL 9.

Going back to the Book 4 model, which I find a lot more attractive, since it leaves a longer TL window for other types of vehicles to be relevant, I'm envisioning this general guideline for the technological maturation of grav vehicles.
TL 9: Standard grav vehicles perform similar to hovercraft. High performance vehicles perfom similar to helicopters.
TL 10: Standard grav vehicles perform similar to helicopters. High performance vehicles perfom similar to subsonic VTOL aircraft.
TL 11: Standard grav vehicles perform similar to subsonic VTOL aircraft. High performance vehicles perfom similar to supersonic VTOL aircraft.
TL 12: Standard grav vehicles perform similar to supersonic VTOL aircraft. High performance vehicles perfom similar to orbital spacecraft.
TL 13+: All grav vehicles perform similar to orbital spacecraft.

The problem is how to explain this in a consistent manner. How grav vehicles work (not their theoretical underpinnings, which don't exist, but how they interact with the environment) has always been rather fuzzy AFAICT. TNE had contragrav negate 99%+ of the vehicle's weight. That essentially made them airships; as with airships it also meant they needed an additional means of forward propulsion (TNE used the standard HePlar thrusters, but TBT for civilian craft, a propeller probably would make more sense.) It would explain the throwaway line in the earliest forms of CT about the Air/Raft being highly vulnerable to wind conditions.

Other technological approches I've being toying with:

- What if grav vehicles did not actually lift themselves up, but manipulated the airflow through around them, creating a gravitic "air cushion" or lift similar to aircraft? That would organically merge them with thruster technology, and it would require a small amount of reaction mass (probably coming from the PP's waste products) for spacecraft. It also would mean - and this could be a feature - grav vehicles could operate on vacuum worlds only by carrying reaction mass as well.
Earlier grav vehicles' performance limitations could similarly be grounded in their limited ability to maintain their "cushion" at higher altitudes and higher speeds.

- In the reverse approach, contragrav could be a sort of "invisible pole" that needs to rest on a somewhat solid foundation, and the stability of that pole would depend on increasing TL, thus limiting ceiling. Similarly, the restricted ability to "tilt" the "pole" would limitd forward propulsion. Unfortunately, I cannot describe it better than with this crude analogy.
It would also return to thrusters being a different application since deep space craft obviously would not work under this principle.

Other ideas for grav vehicle limitations, not fleshed out:
Are grav modules highly susceptible to radiation?
Are they easily disrupted by strong magnetic fields?
Do they need to be powered constantly or lose their function? I.e. if you cut the power, the grav modules would be damaged/scrambled and would need to be repaired/realigned, which takes a long time? (That would be one idea for why tracked or wheeled vehicles are preferable for long expeditions and the like.)

Thoughts?

 

[Rupert]

The problem is how to explain this in a consistent manner. How grav vehicles work (not their theoretical underpinnings, which don't exist, but how they interact with the environment) has always been rather fuzzy AFAICT. TNE had contragrav negate 99%+ of the vehicle's weight. That essentially made them airships; as with airships it also meant they needed an additional means of forward propulsion (TNE used the standard HePlar thrusters, but TBT for civilian craft, a propeller probably would make more sense.) It would explain the throwaway line in the earliest forms of CT about the Air/Raft being highly vulnerable to wind conditions.

TNE also had shrouded props or small ducted fans for grav belts, and ducted fans as alternate tech that would a sensible alternative to HEPlaR for craft that didn't want to be cooking everything behind them and deafening everyone around them.

Other technological approches I've being toying with:

- What if grav vehicles did not actually lift themselves up, but manipulated the airflow through around them, creating a gravitic "air cushion" or lift similar to aircraft? That would organically merge them with thruster technology, and it would require a small amount of reaction mass (probably coming from the PP's waste products) for spacecraft. It also would mean - and this could be a feature - grav vehicles could operate on vacuum worlds only by carrying reaction mass as well.
Earlier grav vehicles' performance limitations could similarly be grounded in their limited ability to maintain their "cushion" at higher altitudes and higher speeds.

- In the reverse approach, contragrav could be a sort of "invisible pole" that needs to rest on a somewhat solid foundation, and the stability of that pole would depend on increasing TL, thus limiting ceiling. Similarly, the restricted ability to "tilt" the "pole" would limitd forward propulsion. Unfortunately, I cannot describe it better than with this crude analogy.
It would also return to thrusters being a different application since deep space craft obviously would not work under this principle.

Other ideas for grav vehicle limitations, not fleshed out:
Are grav modules highly susceptible to radiation?
Are they easily disrupted by strong magnetic fields?
Do they need to be powered constantly or lose their function? I.e. if you cut the power, the grav modules would be damaged/scrambled and would need to be repaired/realigned, which takes a long time? (That would be one idea for why tracked or wheeled vehicles are preferable for long expeditions and the like.)

Thoughts?

Another option to limit altitude would be to require more power the higher from the surface the craft is. Higher TL gravitics need less power per unit altitude, and (some) powerplants get better with TL as well.

 

[Condottiere]

It's quite possible there are a number of different ways to manipulate gravity, and thereby differing results.

 

[Krikkitone]

IMTU the basic (non spacecraft) get essentially the “pole” model, the grav pushes on a large “nearby” mass ie a whole bunch of ground (and nearby gets farther and farther away). The lateral and vertical pushes both have a separate maximum speed.
(The speed being relative to the mass they are pushing on…exceeding it causes your force in that direction to drop drastically…although you could still use the grav plate to push in the opposite direction)

Your Hovercraft->Copter->VTOL->supersonic-> orbital “Practical Performance” seems a good way to describe the effect of the different TLs.

 

[Spinward Flow]

The most important utility of a grav vehicle in an interstellar context is that they can be relatively environment agnostic. You don't need an atmosphere for propulsion/thrust. You don't need an atmosphere for combustion as a power source. This makes grav vehicles the ideal "go anywhere, don't care about environmentals" utility transport. Fusion power plus gravitics is an extremely potent combination for being able to "get around" without needing to sweat the details.

 

[casquilho]

The most important utility of a grav vehicle in an interstellar context is that they can be relatively environment agnostic. You don't need an atmosphere for propulsion/thrust. You don't need an atmosphere for combustion as a power source. This makes grav vehicles the ideal "go anywhere, don't care about environmentals" utility transport. Fusion power plus gravitics is an extremely potent combination for being able to "get around" without needing to sweat the details.

Would this also be true of pure electric ground vehicles?

 

[Spinward Flow]

Would this also be true of pure electric ground vehicles?

Yes, but not to the same degree.
Ground vehicles "must interface with terrain" to move around (using wheels, tracks, legs, etc.) while grav vehicles do not. Grav vehicles can "rise above terrain" so as to not be limited by terrain factors.

An electric vehicle has a LOT less environmental dependency than a combustion vehicle does.
The Apollo era moon rover used a basic 12v car battery as its power source.
The Curiosity rover on Mars uses a radiothermal generator nuclear option as its power source.

 

[Marcatlas]

"CT canon is generally that grav vehicles start being ubiquitous at TL 10"

I always laughed at that pronouncement. At the price they are in CT only the EXTREMELY wealthy could afford them so they are quite rare and not at all "ubiquitous". Remember to calculate using 1 Credit = 6 or 7 current USD

 

[casquilho]

Yes, but not to the same degree.
Ground vehicles "must interface with terrain" to move around (using wheels, tracks, legs, etc.) while grav vehicles do not. Grav vehicles can "rise above terrain" so as to not be limited by terrain factors.

True, me in my electric ATV is stuck when I hit the lip of a Grand Canyon like hole in the ground but, you in your GravBuggy just slide on by.
Good point.

 

[whartung]

I've always considered the air/raft to take off and land with a hum, with very little disruption to the surrounding area. This is what makes them ubiquitous and safe,

The problem with the TNE model is that you have these vehicle wandering around ejecting molten plasma out the back. Fine in deep space, not so much in an elementary school parking lot, not to mention what they do to your wifes roses on the side of the driveway.

And to be ubiquitous, they have to be very safe.

Same with grav belts. Outside the hum or Jetsons bubbling sound, they're safe and local. Not like a jet pack, scattering dust and debris everywhere.

So, grav tech is very Star Wars. Very Johnny Quest, otherwise its just not very fun to be around.

 

[Marcatlas]

I've always considered the air/raft to take off and land with a hum, with very little disruption to the surrounding area. This is what makes them ubiquitous and safe,

The problem with the TNE model is that you have these vehicle wandering around ejecting molten plasma out the back. Fine in deep space, not so much in an elementary school parking lot, not to mention what they do to your wifes roses on the side of the driveway.

Like a Pak Protector torch ship. Love the wife's roses observation!!

 

[Carlobrand]

Grav vehicles being introduced at TL9 is not inconsistent with grav vehicles becoming ubiquitous at TL10. Military often leads with new tech. Commerce tends to be slower about it because they've already got something that works and have to balance the potential advantage against the initial cost of investment and changing infrastructure.

And too, teaching people to pilot something that floats and potentially operates in 3 dimensions is much harder than teaching them to drive down clearly marked lanes in something that takes advantage of friction to resist crosswinds. Grav vehicles would replace aircraft and helicopters pretty quickly, but cars and roads are likely to stick around until the folk born into wheeled technology grow old and die out.

 

[casquilho]

I have always pictured in the built-up areas there being designed air corridors that grav-vehicles would have to remain in. Just like road lanes but these could be stacked as well. I mean with the airspace being shared by vehicles and aircraft and space craft all vying for open space to fly, I imagine it would be very proscribed. I always pictured flying your grav-buggy anywhere you wished would be restricted to planets with little or no populated areas. The wide-open outback so to say.

 

[Tobias]

"CT canon is generally that grav vehicles start being ubiquitous at TL 10"

I always laughed at that pronouncement. At the price they are in CT only the EXTREMELY wealthy could afford them so they are quite rare and not at all "ubiquitous". Remember to calculate using 1 Credit = 6 or 7 current USD

That holds true for the examples in the basic Traveller rules, not so much when using Striker. Even without ignoring the patently nonsensical "no power plants smaller than 1 m³" rule, you can easily built an ICE-powered grav vehicle for less than Cr 10,000. When using fuel cell or battery tech from later rule sets, it's even simpler.

 

[Condottiere]

Personal transport and Amazon delivery are going to be taxi drones, if gravitationally motivated.

So the question is performance, and that appears to require a gravity well.

The low end being:

 

[Tobias]

Another option to limit altitude would be to require more power the higher from the surface the craft is. Higher TL gravitics need less power per unit altitude, and (some) powerplants get better with TL as well.

That's basically what I was getting at with the "pole" model, just with the added consideration that longer "poles" do not (only) require more power, but also more sophisticated grav technology.

 

[Tobias]

I should point out that I mainly meant the utility for typical activities of characters. The basic railroading dilemma that I have encountered, as many other referees have as well, no doubt.
"Mithril's climate is too harsh for an Air/Raft!" "What do you mean by that?"
For planetary expeditions, there is usually no convincing reason at all not to drop in with a grav vehicle from orbit (especially if you have anything other than the standard open-topped Air/Raft), fly safely above any potential land-based trouble. making the referee's carefully prepared encounter tables pointless, and air-recon for what you are looking for - which, on top of everything, is also a much better way of finding stuff than scurrying about on the ground.

And with the standard assumptions (i.e. discounting Book 4), there is not even a TL limitation to this, meaning that your typical TL 11-ish frontier spacers will have no trouble performing the above.

The most important utility of a grav vehicle in an interstellar context is that they can be relatively environment agnostic. You don't need an atmosphere for propulsion/thrust. You don't need an atmosphere for combustion as a power source. This makes grav vehicles the ideal "go anywhere, don't care about environmentals" utility transport. Fusion power plus gravitics is an extremely potent combination for being able to "get around" without needing to sweat the details.

Precisely.
The problem with that being that "sweating the details" makes up a lot of the fun of the game. Wheeled vehicles may still have some utility in safe environments on high-tech worlds for being cheaper. But for all adventuring-related purposes. grav vehicles are so overwhelmingly more useful in every single respect that they render all other forms of transportation pointless.
And my thinking is: How can I mitigate this dominance of grav vehicles just a bit, and just for typical TLs?

 

[Grav_Moped]

Don't get me started.

Grav Vehicles, Grav Drives (thread from 2018). There are others.... lol

 

[Condottiere]

Cost benefit.

If you can get eighty percent done just as well on a wheeled vehicle, at twenty percent of the price, would you?

 

[Tobias]

Cost benefit.

If you can get eighty percent done just as well on a wheeled vehicle, at twenty percent of the price, would you?

Yes, if the remaining twenty percent are crucial. I wouldn't use a minivan instead of an ATV either - even if 80 percent of the time I traveled on roads. Because if I did that, it'd just mean I'd need another whole vehicle for the remaining 20 percent.

Again, player character perspective.