Family grav car spec

[aramis]

A quarter ton of groceries??
Must be an Alaskan thing...

Don't forget 2 sets of football/hockey gear, and/or DIY tools, and/or camping gear... typical stuff for a grocery getter to carry.

A typical set of hockey gear is 20-40kg, and they often have multiples.

It's actually based upon the load limits for a Geo Metro...

 

[Andrew Boulton]

Okay, we'll lose the radio.

Revised minimum spec:

Driver + 3 passengers, 0.5m3 cargo, 100km/h, 8hr duration.

 

[atpollard]

Okay, we'll lose the radio.

That should fix the cost issue.

Part of the problem is the operational regime. Even a flying family car doesn't need a drive system capable of reaching the ionosphere. We need the Grav equivalent of a Wing-in-ground-effect (higher performance at low altitude) so we can reduce the drive size/cost.

 

[far-trader]

Having a quick run at it through MT last night confirms a radio is cheap. Consider it a mid level option (like On-Star service). What's more I was able to get into the mid thousands of credits for TL8 just like aramis for the stated parameters (with radio ). It can be done on the cheap.

Andrew, what are you using for a power plant? Could it be fusion (pricey!)? Or is it one of the more expensive grav options pushing your price up?

 

[aramis]

Having a quick run at it through MT last night confirms a radio is cheap. Consider it a mid level option (like On-Star service). What's more I was able to get into the mid thousands of credits for TL8 just like aramis for the stated parameters (with radio ). It can be done on the cheap.

Andrew, what are you using for a power plant? Could it be fusion (pricey!)? Or is it one of the more expensive grav options pushing your price up?

Striker and MT all have cheap but power-hungry panels available; MGT doesn't. So if he's using MGT, it's because they didn't decide to make a compatible tech paradigm.

That should fix the cost issue.

Part of the problem is the operational regime. Even a flying family car doesn't need a drive system capable of reaching the ionosphere. We need the Grav equivalent of a Wing-in-ground-effect (higher performance at low altitude) so we can reduce the drive size/cost.

If gravitics provide a pure thrust, as is implied, then they can always reach lethal altitudes. What they might not be able to do is operate the PP at those altitudes.

I have seen several modes of gravitic/repulsor craft in fiction...

• paragravitic thrust (CT/MT, some Star Trek novels)
• anti-gravity - cuts gravity's hold on the object by some % (TNE, some space opera novels)
• repulsor - pushes against the ground (Renegade Legion, some other space opera; implied strongly in Star Wars)
• artificial gravity point generated above craft (Variation on the Space Drive of AD Foster's Commonwealth)
• mass nullification - the affected field has its mass reduced and simply floats

Of these, repulsor is the only one that inherently logically produces more thrust closer to the ground. The rest simply accelerate the ship upward.

Note on SW: starwars supplementary materials call it repulsortech, but it operates more like a combination of antigravity and paragravitic thrust... but almost all Star Wars designs show some non-gravitic thrust mode, and they don't produce a noticeable down-force, so if it is repulsion, it's literally climing the gravity gradient, rather than pushing down on the surface area below it.

 

[Andrew Boulton]

I only did a quick guess using FF&S2. I'm sure I can get it lower.

 

[Icosahedron]

Part of the problem is the operational regime. Even a flying family car doesn't need a drive system capable of reaching the ionosphere. We need the Grav equivalent of a Wing-in-ground-effect (higher performance at low altitude) so we can reduce the drive size/cost.

When I houseruled Striker to create my grav vehicles, I adopted a number of features from the Aircraft design sequence. Not only did grav vehicles need aircraft controls, they also needed airframes, and I added a new airframe called 'Ground', creating an ACV equivalent.
Most of my vehicles run on fuel cells within a Hydrogen Economy.

I have seen several modes of gravitic/repulsor craft in fiction...

• paragravitic thrust (CT/MT, some Star Trek novels)
• anti-gravity - cuts gravity's hold on the object by some % (TNE, some space opera novels)
• repulsor - pushes against the ground (Renegade Legion, some other space opera; implied strongly in Star Wars)
• artificial gravity point generated above craft (Variation on the Space Drive of AD Foster's Commonwealth)
• mass nullification - the affected field has its mass reduced and simply floats

Unfortunately, I've never come up with a satisfactory explanation of how gravitic craft work, but for most purposes it's not necessary. It's a handwave.

Edit: Quick calc of grav thrust for repulsors - if a typical flying car is 3m long and 1.5m wide, creating a base area of 4.5m^2, and has a mass of a little over 1 ton, that's around 250kg/m^2 ground pressure, or around 25 grams per cm^2 (assuming an even pressure distribution). You could lie underneath that and it wouldn't even squash your nose.