BRP Vehicle Project - Cars

[Atgxtg]

So where would our sci fi hopper fit in?

Depends on what a "hopper" is and how it moves. It is an antigrav vehicle, some sort of hovercraft/SES/ground effect vehicle, skimmer, flying aircar or what?

If it's a flying aircar type of vehicle, then I'd probably treat it mostly like a jet, with an antigrav "hopper" being able to reduce it's effective mass/weight. Less weight would mean less lift required for maintain level flight, and more power available for speed.

[seneschal]

In Isaac Asimov's "Lucky Starr and the Oceans of Venus" the hero had to use an unusual sporting vehicle to get from one end of the undersea dome to the other: a monopod "hopper" originally intended for racing. It consisted of an egg-shaped cockpit atop a powerful atomic motor perched on a thick mechanical leg. It was agile as a jackrabbit and traveled in 30-foot leaps, fast but not for drivers subject to motion sickness.

[Atgxtg]

Ah. Interesting vehicle. I don't suppose Asimov mentioned it's size or speed in any sort of practical scale, other than the 30 foot leaps? I think I can build something like it using the my vehicle guidelines, but without knowing it's size makes it tougher. I'll do something with the assumption that is is about SIZ 45, the same as a sports car.

I wouldn't think that jumping would be a very efficient means of travel through.

[seneschal]

The hopper was a sort of racing car. A solar system wide fad that came and went.

[rust]

Well, Buridan's Ass has kicked me again ... :eek:

The players of my campaign obviously cannot decide what they prefer, a

water world setting or a desert world setting.

We started with a water world setting, Pharos IV, then moved to a desert

world setting, Enki II, and then to another water world setting, Anuira -

and now I have been asked to write yet another desert world setting.

To hear is to obey, with swiftness and kindness, and so I will indeed write

a new desert world setting, although this time a rather nasty one that is

intended to make the characters' life quite miserable (if I have to do the

work, I also intend to have the fun ...).

A side effect of this all is that I will once again have to change my equip-

ment design schedule: No more water vehicles for now, ground vehicles

instead.

So, perhaps you could tell me the latest version of your ground vehicle for-

mula, especially the version for all terrain vehicles (wheeled and tracked) ?

Thank you very much. :)

[Atgxtg]

For cars, and most wheeled vehicles:

MOV=Square root of (kW/mt) *21

For tracked vehicles (tanks, etc): use *15.75 (75%).

Note that for diesels and other hig torgue craft you might need to increase the kW by about double or so. I7ve got a conversion from torque somehwere, if you need something more accurate.

[rust]

For cars, and most wheeled vehicles:

MOV=Square root of (kW/mt) *21

For tracked vehicles (tanks, etc): use *15.75 (75%).

Thank you very much.

This should be precise enough for my purposes, I think. :thumb:

[Atgxtg]

Why not surprise your players-make an island world.

Just ring all the land masses with tall mountains and have a desert-water world.

Any tunnel-craft?

[seneschal]

The players of my campaign obviously cannot decide what they prefer, a

water world setting or a desert world setting.

We started with a water world setting, Pharos IV, then moved to a desert

world setting, Enki II, and then to another water world setting, Anuira -

and now I have been asked to write yet another desert world setting.

See, you keep making them thirsty with all those desert worlds, which is why they want another water world afterward. Give 'em a planet with a nice, varied climate and not too much garlic salt and they'll be OK.

[rust]

Well, I am quite confident that this will be the last desert world they will ask

for, because this time I intend to really torture their characters with all the

nasty things a desert has to offer ... >:->

They will be stranded, the supply ships will not be coming, their own starship

will be damaged beyond repair, the native life forms will be hostile and dange-

rous, the neighbouring aliens will be bizarre and incomprehensible, the Colo-

nial Office supervisor will be a walking blunder ... yep, I will have fun ...

[seneschal]

Well, I am quite confident that this will be the last desert world they will ask

for, because this time I intend to really torture their characters with all the

nasty things a desert has to offer ... >:->

They will be stranded, the supply ships will not be coming, their own starship

will be damaged beyond repair, the native life forms will be hostile and dange-

rous, the neighbouring aliens will be bizarre and incomprehensible, the Colo-

nial Office supervisor will be a walking blunder ... yep, I will have fun ...

Ah, sort of like Los Angeles, then?

[rust]

Ah, sort of like Los Angeles, then?

Yep, and thank you for reminding me - I need earthquakes, too, of course.

[sdavies2720]

Well, I am quite confident that this will be the last desert world they will ask for...

I predict a jungle world next!

Steve

[Atgxtg]

My money is one an Ice World. How about an ice world with 100% of the surface frozen, but with lots of thermal vents heating the ocean underneath the ice "mantle". You have to drill through 20km or so of ice to get to the ocean. That way you get the worst of both desert and water worlds. Especially neasy if most of the "water" on the ice world either isn't actually water, or is somehow contaminated and undrinkable.

Put something really good under the ice that everybody wants-gold, uranium, elixir of immortality, sexy amphibious girls-and wait for the fireworks.

Worse still, mix n' match. A bunch of rich, sexy, immortals.

[Chvant]

Getting back towards the topic... and as a newbie poster... what has happened to the Vehicles Project generally? I'm still desperate for a system that lets me build really big ground vehicles on Mars, so gravity and air resistance are drastically different, as would be the power to weight ratios too.

Anyone...?

[Atgxtg]

Getting back towards the topic... and as a newbie poster... what has happened to the Vehicles Project generally? I'm still desperate for a system that lets me build really big ground vehicles on Mars, so gravity and air resistance are drastically different, as would be the power to weight ratios too.

Anyone...?

What happened was that I took a break from it. Lots of number crunching and plugging in/testing stats for a variety of vehicles can make me punch happy. When, in the real world, I was helping a friend move some rocks in his pickup truck and worked out how many trips, travel time, etc. in my head using my ideas for vehicles I realized I needed to take a break. The scary part was that my estimates were correct.

But the project is still alive. Ground vehicles are working out well, water vehicles aren't working out too bad, airships are coming along okay, and other aircraft are being a pain. The problem with aircraft being that I can work out a way to design them that is accurate, but it is essentially the same formulas used in real life, and a bit too complex for RPG purposes.

I haven't put much thought into vehicle performance on other worlds. I should try to factor that in. I'd probably try to approximate it, since I usually don't factor in for things like gravity.

For Mars:

Atmospheric Pressure: About 1% of Earth's means lower air resistance for higher top speed. It would also mean that radiators might not work as well (less air going over them to transfer heat too).

Gravity: About 38% of Earths means less weight, but also less ground ground pressure (meaning that it takes larger wheels/tracks to move the vehicle).

The differences in temperature would also require a vehicle to be able to operate in a wider temperature range than on Earth.

So how do all these factors affect ground vehicle performance? Beats me. I'd suspect that probably for the worse, but I don't have enough engineering knoweldge to know for certain.

Fortunately, the folks at NASA have been nice enough to have designed a pair of Mars Rovers (Spirirt and Opportunity) that I can use as test models to work with.

the Mars Exploration Rovers have real world Data of:

Total Mass: 180.1 kg (=SIZ 22 by my SIZ table)

Peak Vehcile Power: 140w =.14kw (+STR2 by my Power/STR table) however most of this power is used to power the computers, toos, radios and other goodies. Only about 10W is used for the drive wheels. So

Drive Wheel Power : 10w = 0.01kw (= barely STR 1 by my Power/STR table)

Top Speed: 30 m/hr. (= .03kph or MOV .033)

Going back a few pages I find my ground vehicle MOV formula of:

MOV= square root (mass/power)*21

Pluging the Mars Rover's numbers into my ground vehicle formula:

MOV= square root(.01kw/180.1kg) *21 = 0.156

Since the real rover's have a MOV of .033, not .156 we can guesstimate that it is only about 20% as fast as an earth vehicle. Since the Rover is also designed to go over rough ground, we probably should use the modfier for tracked vehicles (.75% or K=15.75 instead of 21) so.

MOV = square root(.01kw/180.1kg) *15.75 = 0.117. Since .033 is about 28% of that we can use a K-Factor of 4.44 to get vehicle speeds on Mars.

So for ground vehicles on Mars we could use:

MOV= square root (mass/power)*4.44

Plugging in the stats for the Rovers we get:

MOV= square root(.01kw/180.1kg) *4.44 = 0.033

Ta-dah!

Now, I have no idea how accurate this really is. I've only got one test model to go with, but that means practically no one else has any idea how accurate it is either. So it will be hard for anyone to disprove it, and heck it's only a game.