Quite right. By the Navis Primer the Imperium of Man basically can't have anything more than Astropathic contact with its constituent parts. Anything else would take too long, not to mention be too unreliable since the risk of loss of the craft is ridiculously high.

Fortunately GW actually has published some very, very different numbers that makes rather a lot more sense.

Interesting, do you have a link or info on where this can be found?

On these very forums, in fact!

The topic has been discussed several times before , and the discussions led med to compile this little chart of typical travel times within the Calixis Sector. Also available as a little handy web-tool

Edit: The source for these discussions was White Dwarf 139:

The time differences between real space and warpspace are quite drastic. Not only does time pass at different rates in both kinds of space, but it also passes at very variable rates. Until a ship finishes its jump, it is impossible for a ship's crew to know exactly how long their journey has taken. Time passing in real space is referred to as real time. Time passing on board a spacecraft is referred to as warp time. The relationship between real time and warp time is shown on the chart below.

So, for example, a 100 light year jump will seem to take from 2.5 to 9.5 hours to a spaceship's crew, but between 3 days and 3 weeks will have passed in real space. These times do not include journey times out to and from jump points on the edge of the star systems. It takes from days to weeks of travel at sub-light speeds to reach a drop from the spaceship's starting planet, and a similar time to re-enter the destination system.

The Imperium is approximately 75 thousand light years from edge to edge. A journey of this length would take between 75 and 300 days in warp time, and between 6 years and 40 years real time.

Our group uses this compromise between FFG's Darh Heresy flavour and GW's travel times

I did this for Rogue Trader yonks ago: Eisenhorn's actual warp capable ship. Not what the OP was after, really, but here for completeness:-

Isolde Pattern Bulk Clipper

“The Essene was three kilometres long…and fully seven hundred metres deep at its broadest part. Its nose was a long sleek cone like a cathedral spire made of overlapping gothic curves and barbed with bronze finials and spines. Behind that bladed front, the angular hull thickened into muscular buttresses of rusty-red plating, looped and riveted with ribs of dark steel. Crenellated tower stacks bulged from the dorsal hump. Hundred metre masts stabbed forward from the hull like tusks, and other, shorter masts projected from the flanks and underside, winking with guide lights. The rear portion of the juggernaut splayed into four heat-blackened cones, each of which was large enough to swallow a dozen gun-cutters at once.”

-Eisenhorn, Xenos

Isolde pattern Bulk Clippers represent something of a failed experiment; an attempt to combine the speed of a Clipper with both the greater freight capacity of a bulk Transport and the armour of a warship. The fact that the class was unsuccessful in truly achieving any aspect of this triple purpose has not reduced the affection with which these ships are held by starfarers, a fondness rooted in their extraordinary beauty.

Constructed in the now legendary Larland shipyards (themselves lost to heretical industrial sabotage over three millennia ago) the ships attempted to build upon the success of the earlier Orion-Class Star Clipper. The Orion was a finely balanced thoroughbred, and the Archmagi Shipwrights of Larland hoped to enhance the survivability of the class by overcoming certain calibration shortcomings that had precluded the mounting of additional armour.

Unfortunately, this was never properly achieved. The gradual realisation among the Larland Technomagi of the new Isolde Class’ inability to comply with any aspect of the contractual Carta Confabricor led to a five decade round of buck passing and finger pointing, culminating in a series of disastrous enforced design compromises.

And yet, despite its compromised origin, the Isolde has, in the fullness of time, come to be regarded as one of the most visually arresting vessels within the Imperium. Resembling its parent, the Orion, it is at once heavier yet somehow more organic and lithe. Constructed by the Larlanders from the finest materials (largely with a view to distracting potential purchasers from its shortcomings) it effortlessly catches the starlight, reflecting it across languidly elegant bronzed plating, smoothly dappled stained armourglass and electrum-coated buttresses that make the architectural features of the most magnificent Imperial cathedral seem dull and provincial in comparison.

Dimensions: 3 km long, 0.7km abeam at fins approx

Mass: 8.7 Megatonnes

Crew: 16,000 crew, approx

Accel: 3.6 gravities max sustainable acceleration

Speed: 7 Manoeuvrability:+15

Detection: +10 Hull integrity:38

Armour: +12 Turret Rating: 1

Space: 38 SP: 25

Weapon capacity: 1 Port, 1 Starboard

Cargo Hauler: This vessel was designed for transporting goods, and no amount of retrofitting can fully change this. This Hull comes pre-equipped with one Main Cargo Hold Component (See page 203 of the Rogue Trader Core Rulebook). The hull’s Space has already been reduced to account for this, however when the ship is constructed it must be able to provide a total of 2 power to this component.

“A beauty.” This vessel draws admiring glances from all those who know about spacecraft. Anyone associated with the vessel is deemed to gain a +5 bonus to fellowship when dealing with the voidborn or anyone with the Pilot (Space Craft) skill.

Jaq Draco, from the Inquisition War series, used a warp-capable courier of ancient providence that was quite small; I believe it was described as being shorter than 300 meters. It was almost all engines and field generators, and had almost no space for crew or passengers beyond his retinue.

Of course, I have seen a lot of vehemence directed at the content of those novels.

-=Brother Praetus=-

The Inquisition War series is also old enough to have more than a few things not in the current amount of info that amounts to "semi-canon" that GW enforces.

Jaq Draco, from the Inquisition War series, used a warp-capable courier of ancient providence that was quite small [...] Of course, I have seen a lot of vehemence directed at the content of those novels.

The Inquisition War series is also old enough to have more than a few things not in the current amount of info that amounts to "semi-canon" that GW enforces.

The fact that the main character's name is ' Jaq Draco ' tells you everything you need to know about how seriously you should take that series...

As much as I take my player's favorite npc to have when he runs WFRP Noki Darktear?

In the "Eye of Terror" novel the Rogue trader also has a small warp capable ship... but I don't know if that book is considered 100% canon these days. The description of chaos is however pretty good in that book if you want to test your insanity a bit.

I believe that the Squats have ready access to small warp-capable craft.

I believe that the Squats have ready access to small warp-capable craft.

I assume this is supposed to be humorous...?

re: Dan Abnett taking liberties.

Neither of the RT ships in his books have been small, we just don't see much of the crew of the latter, even though they're not all servitors (which they have rules for in RT).

And the light-sabre... isn't actually new, if I recall correctly. They're just **** obscure and were archeotech before they eventually fell out of sight completely.

I don't ever recall reading anyting definitive about the minimum size for a warp capable craft. In the older fluff there are several examples of small warp capable craft, but that's very old fluff. Small warp engines might not be archeotech. There's lots of reasons not to build them that small. The engines are clearly expensive and made in limited quantities. Making a small ship warp capable is, even if it is not archeotech, an flagrant expenditure of vast amounts of wealth for little return. Far better to make them for a freighter capable of hauling megatons of cargo or a warship capable of projecting the Imperium's might than a glorified landing craft. Only an absurdly powerful individual or institution could have it done and such a vessel would be good for only a limited variety of uses.

As for the vessel in the Abnett story at the beginning of DH2, it's clearly refered to as a landing craft. Which is good for the characters because it means that they have a way off world besides their wrecked dropship and however their metal faced boss arrived.

Edit: You also want to be in vessel large enough not to go stir crazy and with a very well equiped galley if you get stuck in the warp for any length of time.

Warp capable ships are massive. Eisenhorn berthed his gun cutter on rogue trader vessels. He had a favorite RogueTrader he used whose entire ship was crewed by servitors only. The trader himself was more machine than man. Overall, it's your game and you can do what you want. An archeotech or xenos vessel may work for you if it has to be small.

Gun cutters though are not warp capable by the fluff.

Well, "the fluff" is subjective and contradictory 50% of the time ...

Just depends on where you're looking. And there's a reason people have coined the term "Abnettverse".

In the HH novel "Nemesis" there was a small warp capable ship used by the Officio Assassinorium. This was basically a Two stage craft. The first part was the Warp/Plasma drive which housed the navigator, Gellar field generator and everything the ship needed for long range transits. This connected to what seemed to be a pretty standard guncutter which would house the mission team and detach in order to land on a planet.

I can't see why there would not be at least a couple of these "tech relics" still in existence! As to the minimum size of a warp drive? About the size of a large backpack! After all, This is what Grey Knight interceptor squads use even their most recent iteration! (A personal teleporter is basically a tiny warp drive in 40k).

I wonder if it's not the warp engine that requires a ship to be big, but the gellar field generator. Maybe more mass is required to maintain a safe gellar field.

I like the idea of the cutter acting like the bridge of a ship detachable from the warp engine/gellar field generator.

I like the idea of the cutter acting like the bridge of a ship detachable from the warp engine/gellar field generator.

Aye, reminds me of that Jedi Starfighter from the Star Wars prequels, though I'm sure similar ideas can be found elsewhere in sci-fi as well.