DIY starship part 1

As there is no tutorial on how to design ships with the Intercept design system I will do just that here. You can get the rules, design system etc here.  

Open Data.xls first       

The design system consist of two files; Data.xls that contains the design tables and Ship.xls that will hold your design. You must open the Data.xls first so that Ship.xls can read from it, then you open Ship.xls and save it with whatever name you want, typically the ship class name of your design (Suleiman.xls or Scout.xls in our case). The renamed Ship.xls files should reside in the same folder as Data.xls to simplify things.       

Suleiman type S scoutship


Known facts about the Suleiman       

Before starting a design you should have a rough idea on what the ship must be capable, how much it can cost and how large it should be. Our example is the Suleiman class type S scout ship, known from the Traveller roleplaying game, so we already know a few things about the ship. It is a 100 dTon ship with J-2 and 2G of acceleration. The TL varies depending on ruleset, we choose TL 13. the ship has four double occupancy staterooms so we should give it lifesupport for 8 people. The ship is armed with a single turret holding a laser, a missile launcher and a sandcaster, we’ll change that to a top mounted turret holding a laser with a missile launcher and a small belly mounted turret with a sandcaster. We set the cargo space to 5 dTons. The Suleiman should cost around 40 MCr.       

Design basics       

IMTU the dTon is 5 m3 instead of the usual 13.5, 14 or even 15 m3 (the sources differ on this one). In the top left corner of the design sheet there is a dark yellow cell holding the value 15. Change it to whatever value your Traveller system uses for the dTon, the value chosen won’t affect anything except the ships mass. If you enter something other than 5 the design system assumes you will input hull size, cargo space, crew area etc in dTons and power in EPs (High guard Energy Points), if you enter 5 exactly the design system expects m3 values for volumes and MWs (Mega Watt) for power. My 5 m3 designs assume 25 MW equals one EP, the value of the EP has no effect on your designs otherwise. Note that all cells depend on the value of the dTon are dark yellow in color. Cells that can be edited are yellow in color, just leave the input cells empty if you don’t want that particular component. The Components column summarize the values for each component.       


The hull      

We set the hull size to 100 dTon as we know that the Suleiman is a 100 dTon ship from Traveller canon (if you use the 5 m3 variant you must enter 500 m3 instead). We set the hull TL to 13 and we add 3 to the armor. IMTU the Suleiman has extra armor to make it a rugged and tough ship built to withstand lower tech attacks. If we ignore the extra armor we shave off 1.5 MCr. Material type (basic, advanced or extreme) are abstract terms for how advanced the hull materials used. Material type affects volume and mass of the hull, hull price goes up sharply if more advanced materials are used. We give the Suleiman Advanced materials and a frame that can withstand 2G of acceleration. The G rating in parenthesis is the G rating modified by ships density, the value before the slash is loaded and after the slash is unloaded performance.

There are four degrees of streamlining in Intercept    

  • Open frame Suicidal to use for aerobraking or skimming. 150 km/h safe speed in 1 atm. Lots of surface area, good for mounting weapons and sensors but bad for armor.
  • Normal Dangerous to use for aerobraking or skimming. 500 km/h safe speed in 1 atm.
  • Streamlined  OK for aerobraking or skimming. 1000 km/h safe speed in 1 atm. Less surface area.
  • Airframe Good for aerobraking or skimming. 3000 km/h safe speed in 1 atm. Little surface area.

Surface area limits how much weapons and sensors you can add but you can increase surface area by adding wings to your ship (as a percentage of hull volume). Wings have no further effects in space combat. We give the Suleiman Streamlined airframe as a compromise between airspeed and surface area.     

The Suleiman is supposed to land on planet so we give it skids as Traveller canon illustrations doesn’t show it with wheels. As the Suleiman should be able to skim fuel from gas giants we also give it fuel scoops. Fuel scoops allow gas giant skimming given a hull with good enough streamlining and it will also turn the fission or fusion thrusters into airbreathers that use the surrounding air as remass  drastically reducing fuel use and radioactive exhaust when moving in an atmosphere.     

There is no stealth in space     

That is what they say at Atomic rocket and I agree in general, any realistic thruster will have a signature that is easily detectable at huge ranges (if our Suleiman would have 2G Fission drive, it would be trackable by a similar ship to 0.7 AU). Intercept however, allows us to use reactionless drives with no visual or IR signature and so stealth does play a part here. Also note that while the signature and sensor rules in Interecpt are based on real world data I have on purpose reduced the sensor capabilities to suit my Traveller campaign. In Interecpt there are separate stealth systems against Visual, IR, radar, Neutrino and Mass sensors. Each stealth system come in three qualities (none, basic and advanced). Aside from price, each stealth system use up surface area so you cannot really make a super stealthy ship with a full load of weapons. Tradeoffs, it is all about tradeoffs. As our Suleiman deals with lower tech cultures we give it basic visual stealth (make the hull really black) to make it harder to detect with visual sensors. This reduces its Vis(hull) signature by 2.     

Suleiman propulsion design     


A ship needs a propulsion system unless it is a space station you are designing. Propulsion come in three forms:     

  • Fission / fusion thrusters that need remass to operate and need to track thrust expenditure. The drive capabilities are based on the more extreme technologies from the Atomic rocket site.
  • Reactionless thrusters that use electricity to create reactionless thrust (and break the laws of physics).
  • Jump drives use jump fuel to enter hyperspace and travel a number of parsecs in a week (breaking more laws of physics).

We give the Suleiman a 2G Impulse drive and a J-2 jump drive. We add jump fuel for 3 parsec to help it survive if a misjump occurs. 



Right now there aren’t that many choices to do for power but the empty row on the design sheet will eventually hold some kind of energy storage banks. Simply choose if you go with a fission or fusion powerplants and the number of EPs it must produce (or MWs if the dTon=5 m3 option is used). A legit design should have enough power to support everything except the Surface fixtures segment (sensors and weapons if you will). Our Suleiman has “Protected radiators” noted for its powerplant but your design may instead say “Vulnerable radiators”. If a ship has more than 2 EP per 100 dTon (more than 50 MW per 500 m3 hull if dTon = 5m3 is used) the powerplant must have extendable radiators and those are less armored than the rest of the ship. This is automatically reflected in the ships ratings. In reality, all ships will have vulnerable radiators, even the space shuttle with its puny power output must extend the cargo doors are cooling fins when in orbit.   

Well, this is all for now, in the next installment we will cover Payload, Crew and Surface fixtures. Feel free to ask questions here at the blog or through e-mail.  

So long and keep the solar wind to your backside.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: