What up G? Handling gravity IYTU...

[aramis]

Gravitics cost more like 30x as much as ground based ICE per passenger, or more. Plus 30x or more the maintenance costs. Plus they still require groundside infrastructure (Landing pads) and positive ATC for safety. You're trading a shared infrastructure of one form for another. And you STILL need roadway maintenance for pedestrian roadways... and they don't hurt to have roadways for bikes, either.

Oh, and the few canonical city maps we have are special cases... Leedor on Aramis is entirely underground, and uses slidewalks. For nighttime use, they shut those down so the electric cars can make deliveries.

For comparison: the ground car in MT is Cr3100. The Air/Raft is Cr275,000... 90x the cost, and 90x the maintenance cost, and only 40kph faster (120 vs 80), tho with 10x the fuel endurance.... for 15x the overall range.

The Imperial Capital has almost no POV of any kind - it's a flying arcology.

 

[Hyphen]

Given that modern trackage ( plus signalling) can cost anywhere between 3 to 30 million dollars per mile for roadbed, track, and signalling...

So you use somthing that doesn't need a lot of these things, such as a monorail (track but no roadbed) or Heinlein's trains that jump through magnetic hoops, from - ooh, which one, maybe "Have Spacesuit, Will Travel"?

There's as many - if not more - problems with "everything flies" as there are with today's "everything drives". Overcrowding, for one thing. Can't fly flat out, so speeds are not as great as you may think. Try reading "Vertigo" by Bob Shaw; not only is it a cracking good read, it also shows you the consequences of anti-grav tech. (You may like to try "A Little Night Flying" first.)

 

[Ishmael]

... Plus they still require groundside infrastructure (Landing pads) and positive ATC for safety. You're trading a shared infrastructure of one form for another. And you STILL need roadway maintenance for pedestrian roadways... and they don't hurt to have roadways for bikes, either.

not really...
Landing pads are functionally identical to parking spaces, which I do not consider to be part of the road/rail transportation network. They are places to hold the vehicle when its not actually being used.
Pedestrian walkways/bike paths don't have anywhere near the same construction costs and maintenance of a full road or railway... a sidewalk's load capacity is minute compared to roads/rails.

For comparison: the ground car in MT is Cr3100. The Air/Raft is Cr275,000... 90x the cost, and 90x the maintenance cost, and only 40kph faster (120 vs 80), tho with 10x the fuel endurance.... for 15x the overall range.

For comparison, in MT I did a quick build of a ground car and a grav car of similar capabilities.
A 13.5kl van with 4 cramped seats and 100kg cargo with a 4 hr endurance. Basic life support included heat and lights for the interior ( window defroster and map-lights )
I didn't do a full write-up...just enough to compare the two.
One had a .25Mw ICE*, typical suspension, etc. and cost a little over 3000 Crimps (3200?)
The grav van had a .40Mw MHD turbine, std grav modules, and cost between 30,000 and 35,000 Crimps.
The grav van had 4 tonnes thrust and could go quite a bit faster than 120kph although I did forget to check MOE flight.
The wheeled van uses enhance mech controls ( ~.3cp's needed )
the G-van uses a model0 comp and computer linked controls ( ~3cp's needed )
These are back-of-envelope numbers....

The manner of determining top speed is stupid.
for ground vehicles, power/mass ratios are for acceleration, not top speed... top speed is reached when power at the wheels equals total drag from rolling resistance and aero drag.
The same goes for grav vehicles' thrust loading.
The way Traveller does things concerning this matter is just wrong.

So you use somthing that doesn't need a lot of these things, such as a monorail (track but no roadbed) or Heinlein's trains that jump through magnetic hoops, from - ooh, which one, maybe "Have Spacesuit, Will Travel"?

Monorail, so far, is more costly and has less load capacity than standard rail. Monorails cost can be as high as 240 million per mile and is only used in passenger service thus far.
Heinlein's trains sound a good deal like maglev trains. They cost anywhere from 30 to 70 million per mile although they claim to have less maintenance than standard rail due to having no moving parts. Present power requirements are between 1 and 2 kw per tonne to lift and move the load a few mm's off the track.

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Gee, it sounds as though like aramis is presenting arguments as to why grav tech shouldn't per used in the OTU because of high cost making it economically inferior when compared to old ground vehicles. But the OTU does have ubiquitous grav tech into which all other forms of transport eventually merge ( according to ref's companion tech section ).

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* a 250kw output ICE masses 1 tonne yet has a volume of only .001 kl? WTF??
( as per original MT rules...is there errata for this that I've missed? )

 

[rancke]

Oh, and the few canonical city maps we have are special cases... Leedor on Aramis is entirely underground, and uses slidewalks. For nighttime use, they shut those down so the electric cars can make deliveries.

It's not canon, but if you have a subscription to JTAS Online you can find a map of Atora, capital of the Duchy of Regina, that I designed to be entirely for grav cars (plus pedestrians and bikes at the ground level). There's also a map of Regina Startown (in another article) that presupposes grav vehicles.


Hans

 

[aramis]

* a 250kw output ICE masses 1 tonne yet has a volume of only .001 kl? WTF??
( as per original MT rules...is there errata for this that I've missed? )

Yes.

 

[Icosahedron]

IMTU, I use the 'fusion tunneling tech' that hollows out asteroid hulls for ships. This creates stable, vitrified road surfaces across any terrain in seconds, at minimal cost. A metal strip embedded in such a surface is the basis for maglev trains.

Whereas the cost of such infrastructure is high compared with the difference between a single grav vehicle and ground vehicle, a newly settled world will compare the costs of the projected numbers of vehicles over the life of the road network, and it may be that the cost of the network is lower than the cost of all those grav vehicles combined. Pre-existing colonies probably already have roadway infrastructure.

We have the tech for personal air transport now - but we choose not to implement it (except for the very rich). Why should the future be any different?

 

[rancke]

We have the tech for personal air transport now - but we choose not to implement it (except for the very rich). Why should the future be any different?

Because the setting material says so?

"Tech level 11: Gravitic vehicles blend the various transportation technologies (air, land, and water) into a single technology." [RC:33]​

There may be some threshholds in terms of population size needed to support grav module production, but that's a notion of my own with no canonical support.


Hans

 

[BytePro]

...
We have the tech for personal air transport now - but we choose not to implement it (except for the very rich). Why should the future be any different?

The future, by definition, is different!

In Traveller's case - the definition is that 'grav vehicles are the main transportation of a high tech society'. Past TL 10 other vehicles are rarely seen. Nothing is said directly about mass transit - but grav easily substitutes for maglev <shrug>.

Traveller seems to 'break' this model with its costs, unless one assumes (perhaps rightly) that higher TL worlds have substantially greater personal incomes and/or less personal transportation requirements.

As to RW and 'personal air transport' - that is a cart before the horse and mass market economics thing. If air cars where cheap enough they easily could have replaced ground cars.

I'd add safe enough and fuel efficient as well, but then look at the situation with cars today and that really doesn't hold up - they just have to be affordable and insurable. (In fact, ironically, air might be safer, in the sense that one has another dimension to dodge into and controls would likely require more automation in the first place. Computer control of acceleration and cruising, along with less restrictive routing for air, might actually be more fuel efficient than most American cars [Europe and the rest of the world has more fuel efficient cars than America]...)

For the past 30 years one could buy personal air cars - except the high cost, lack of support and lack of jurisdictional regulations (requiring treatment as helicopters). Of course, if one adds up all the personal taxes spent on road infrastructure, a respectable percentage of Americans could easily afford air cars. And with such sales, the costs could have plummeted, allowing for an even larger market.

Our RW situation is but one model for how things work out - it was a fluke of history (WWI and the Navy's requirements) and individual successes (AC Delco's electric starter and Ford's initial use of low cost labor) and greed ('power wars' and Standard Oil) that replaced the electric car with the ICE. Well, at least temporarily.

 

[Ishmael]

finally got that errata and have a few comments about it.

The high cost of grav vehicles seem to stem a great deal from the idea that all flying craft should have 2 computers. But as I read the rules, it is not required; the rules use words such as "should" and "choose", not "must" nor "shall". They are simply recommended to provide redundancy for linked controls. Linked controls do not function without computers.
This goes along with what I read in Striker, where there are no computers of the sort used in MT, however, NOE speed is limited by what is allowed from avionics packages.

The errata seems to indicate that a single person can monitor/control up to 12 kls of panels which, given the low CP ratings of unlinked panels, could only give control to relatively low-cost machines. Essentially, no computer means no CP multiplier and no linked controls. mechanical and electronic controls should be fine though.

This would cut the cost of the given example air raft by 120,000 cr and add the cost of avionics @10,000 cr to allow NOE flight.

 

[dean]

finally got that errata and have a few comments about it.

The high cost of grav vehicles seem to stem a great deal from the idea that all flying craft should have 2 computers. But as I read the rules, it is not required; the rules use words such as "should" and "choose", not "must" nor "shall". They are simply recommended to provide redundancy for linked controls. Linked controls do not function without computers.
This goes along with what I read in Striker, where there are no computers of the sort used in MT, however, NOE speed is limited by what is allowed from avionics packages.

The errata seems to indicate that a single person can monitor/control up to 12 kls of panels which, given the low CP ratings of unlinked panels, could only give control to relatively low-cost machines. Essentially, no computer means no CP multiplier and no linked controls. mechanical and electronic controls should be fine though.

This would cut the cost of the given example air raft by 120,000 cr and add the cost of avionics @10,000 cr to allow NOE flight.

Er, you can't even buy a "ground car" nowadays that doesn't have a computer in it. And "avionics packages" are nothing more than single purpose computers.

Perhaps not a "starship"-type computer, but I really don't see any Grav vehicle not having a computerized control system of some sort.

 

[Timmy]

From the Megatraveller Jounal, use robot brain for vehicle computer, has some low cost grav vehicles as well.

 

[Timmy]

My mistake, Travellers' Digest 20. Affordable Transportation - Budget Grav Vehicles.