VL to KG conversion the t20 vehicle design sequence

[Michael Taylor]

This may have been dealt with somewhere before, but in TA6 it states 1vl equates to 1kg of weight. But in the THB 1vl = 10 litres. So what is the actual conversion between vl and KG? (I'm looking for an averaged conversion because i'm aware of the whole weight vs displacement issue).

thanks

Mike

 

[tjoneslo]

The problem is that VLs represent both weight (kg) and volume (liters or m^3). The THB gives one conversion, TA3, TA6, TA8 all give the other. The precise conversion of Vls to either weight or volume depends upon the craft you are building.

1 liter of water weights 1kg. The conversions state 1 vl weighs 1 kg and takes up 10 liters of volume, therefore 1 vl has a density of about 1/10 that of water.

I thought hard about including a rule in the TAs that would exclude the VLs from calculating the volume of a craft, meaning the more armor you included, the higher density your vehicle is.

IMO, The real conversion is about 1vl = 1 kg = 1 liter, with some variation for heavily armored or open frame vehicle (like boats). Some people have found that for 1vl = 10 liters, the volumes of the craft come out about right.

So there is no good answer. Using the abstraction of VLs was a mistake, but one made with the idea that no one much cares about doing precise conversion from VLs to real units.

 

[Michael Taylor]

Heres another curly one then. If i'm designing a missile with a rocket drive train (current assumption for this drive train: 1vl: 0.1EP, 20 TH - the EP is per 6 second round: 12vl fuel to generate 1 EP), then on what basis in reality could you add agility to a rocket/missile. I am driven, after hours of research , to come to the conclusion that you cna only add agility to a missile by increasing the amount of EP generated by/supplied by the rocket fuel, not by another power source like a battery. There simply does not exist in reality an example where a missile (like Stinger or javelin or patriot) is more agile because it has a clunking great big battery in it. It is more agile/has a higher AC because it has better programs running on its onboard computer or because it has more EP available for its rocket drive train. What's your opinion on this TJL?

 

[tjoneslo]

The important missing piece here: The rocket engine subsumes both drivetrain and power plant.

In order to build a proper jet engine you need to have both a jet drivetrain and a turbine to power it. So for the rocket engine, you need to have a rocket drivetrain plus a rocket power plant.

Yours is 200TH, 1 EP, 10 vl, (which is a little better than mine at 70TH, 5 vl, 9vl fuel/hr, Cr700 per unit).

We now need a rocket power plant: 120 vl per hour, 1 EP produced, 2 vl. This make the rocket 8 vl in size. This now lets you overproduce rocket power plant, for the additional agility.

Final Stats:
Rocket drivetrain: 200TH, 1 EP, 8 vl, Cr700 per drive unit.
Rocket Power Plant: 2 vl, 1EP, Cr 700, 120 vl per hour. Note this is a terrible fuel consumption but it produces thrust on the order of the Grav units. The Rocket drivetrain requires a rocket power plant, and the only drivetrain the rocket powerplant can produce power for is the rocket drivetrain.

 

[Michael Taylor]

I dont agree you need a powerplant for the rocket DT. The rocket is the powerplant, or more correctly, the chemical fuel for the rocket contains the EP required to power the rocket DT.

 

[tjoneslo]

It's true that a rocket does not need a powerplant. But to make the rocket engine work within the context of the T20 Design system, particuarly with the agility, you need to split the engine into a drivetrain and a power plant. The two are physically one unit, but for the abstraction of the design system they are two units.

How do you build a jet engine? In the T20 Design system you need a jet drivetrain and a turbine power plant. Like a rocket engine, a jet engine shouldn't need a "power plant", it is a power plant.

This is one of the limitations of the abstraction of this design system.

 

[Michael Taylor]

I see. But i've assumed solid rockets for the missile design system, and solid propellants don't require any fuel pumps. The drive train is simply the nozzle at the end of the rocket. I understand what you are saying about abstraction. MJD will send you something i've done for you to critique.

 

[tjoneslo]

Random thought process.

The abstraction we are trying to figure out is the "Agility". So having a solid rocket "drivetrain" doesn't require any power plant. This also doesn't give your rocket any agility. Agility assumes some manner of steering: very quickly and under hostile conditions. To do this with a rocket requires either an airfoil (fins or wings) or adjusting the nozzle of the rocket. Powering these actuators requires a power source, like a battery.

So yes, you can add agility to a rocket by adding a big battery. It doesn't add to the thrust of the rocket, it just makes sure the thrust goes in the proper direction.

I'd be more than happy to review things. Either email or PM me.

 

[Michael Taylor]

In the light of your last post I need to amend what i've done. Iassumed you could not add agility with a battery power source for a rocket. If you can, I will need to start from scratch. My work email is michael@umc.co.nz. Send me an email and I will forward what i've done to you.