Using Traveller ships and deck plans for ships with reaction drives

[Thot]

Winchell's calculations on Project Rho / Torchships calculate a plasma torch drive with 0.3-g acceleration requires 450 GW of power and puts out 0.108 kilotons/second. And that's just an 8.3-hour burn to 90 km/s, coast, flip, and burn for another 8.3 hours to stop. It's not constant acceleration.

He also calculates that you can reduce the power requirements by 90% (close to a Saturn V stage-one thruster) and only add a few days of travel to a weeks-long journey.

450 GW is a lot of power, and a requires a lot of fuel.

For reference:

• A Nimitz class carrier of the US Navy (100,000 tons) has a total of 200 MW from its reactors. Less than 0,05% of 450 GW.
• The total electricity generation of the USA in 2015 was around 1000 GW.

In Winchell's calculations, he's imagining a 1000 metric ton (1,000,000 kg mass) ship carrying half that much in fuel (500,000 kg). These tons are the same weight as Traveller's tons of hydrogen (whose volume make up our displacement-tons). So that 1000-ton ship is actual mass, not displacement.

Didn't someone share a tonsOfDisplacement-to-tonsOfMass ratio elsewhere?

Judging from my GURPS Traveller books, the ratio should be roughly 1:10. Which makes sense, in that way, the total ship's density would slightly below 1.

 

[Thot]

I have made a few more thoughts about this, and posted the resulting document here:

http://www.heinscher.de/sonstiges/traveller/ConversionOfTravellerShips.pdf

 

[Xerxeskingofking]

ok, I;m way late to the party on this, so sorry if this has been brought up before, but have you seen the rules for reaction drives in the MgT high guard books?


I get the feeling, form what little I have read in this thread and your chemical rocket third imperium threat (which I quite enjoyed reading about, by the way), that your going for a much more "realistic" feel to your game, with talk about Delta V and Isp, but Mongoose came up with a fairly simple, easy to use system that slots well into their overall game system without too many changes, but still adds significant restrictions on what reaction drives can do and makes the ships something the players think about differently (with fuel exhaustion being a real concern they need to watch out for).

 

[mike wightman]

The MgT reaction drive is pure made up handwavium with no basis on real world physics.

 

[kilemall]

Thot, perhaps you should take a look at Triplanetary the game. Predates ALL of Traveller, and has fuel burns with the occasional very expensive torchship (fusion drive). At the least you would have a map of Sol system to burn around in.

https://en.wikipedia.org/wiki/Triplanetary

http://www.sjgames.com/triplan/

http://www.ebay.com/itm/GDW-Wargame...608775?hash=item544a77a887:g:mcYAAOSwwzhZWPpl

 

[Xerxeskingofking]

The MgT reaction drive is pure made up handwavium with no basis on real world physics.

I am perfectly aware of that, and I acknowledge as much in my post. I was just asking if he'd considered it as a possible example (maybe by upping the g-turns to something more "realistic")

 

[Takaholic]

The info concerning the Imperium's Jump-6 secret express route is given in the MegaTraveller Rebellion Sourcebook, pages 15-16. It is canon, not just rumor.

 

[Thot]

After having fiddled with the numbers a bit, I found that actually, the above mentioned relation of 1:3 for dton to mton conversion is quite pessimistic.

It is actually rather possible that 1:1 for a chemical-rocket, fuel-cell driven ship would be a better, more realistic relation.

This will slightly increase the delta V in the document, by about 1.5 to 3 (the lower the volume percentage of the fuel, the higher the multiplier for the delta V).

I am going to update the document with this new information.