What is the largest normal craft that can land on a planet and take off again, exculding the obvious Kroot Warsphere? According to much of the background material, escorts and (normal) traders could land their ships on a planet and take off, capital ships being too heavy. And if we were to translate this to RT, what would be the best way to convert it?

I myself am considering a combination of the planet size and the ship size, not so much as the class. With a large/medium/small planet allowing the use of 6/8/10 megatonnes crafts respectively, or something in that vein. If it is allowable, in fact.

Friedrich van Riebeeck, Navigator Primus, Heart of the Void

If i remember correctly largest size to land on a planet is the frigate. Dunno where i read it though.

I seem to recall that in BFG Transports and Escorts (Raiders and Frigates) could land on planets while larger ships cannot. I can't give a page reference off of the top of my head, though.

BFG specifically states so in the advanced rules, "Fighting in Low Orbit". Here they clearly state that escorts and transports can land, while capital ships cannot. As an extra, the rules for Ork attack ships specifically repeat that they can land on planets carrying warbands and their vehicles plus artillery.

Size seems to be the prime limitation in this question. As such, I would rather use size in megatonnage then the class of a ship. It makes little sense that a Goliath or Universe Mass Conveyor could land, while a light cruiser could not. As much sense as the fact that the universe can make tighter turns then a Dauntless in RAW.

In a way, this would make the relatively small Imperial basic transports very logical ships. Being able to land on a planet offers enormous advantages in importing and exporting bulk goods. The image of small lighters taking up vast loads of ore a bucketload at a time has in each case never appealed me. Loading and unloading cargo with sloops makes only sense if it is high value cargo with limited bulk (or shamefully if it can climb aboard itself of course). This would give a clear distinction between the 'high void' transports, too large to land on planets and depending on space stations to transfer their cargo to 'smaller' ships and lighters for planetside destinations and 'landing' transports that could load and unload directly on planets lacking such well developed facilities. A bit like today, where the truly vast container giants can only use a few ports, their size restricting the use of smaller facilities, that are on their turn served by smaller ships. The big ships make far more efficient cargo haulers, being able to carry vast amounts in their huge frames, while the smaller ships are less efficient but more versatile, having far more 'ports of call'.

As an added bonus, this would make spaceports a real objective on planets. Landing a vast voidship is one thing, the spot where it lands is a second. A swampy plain does not seem a good option. The logical place would be a large flat surface on a very stable, strong bedrock, fortified by human engineering to enable it to accept the weight of a small hive. We are not talking of putting down one of these ships on any spot of the planet! This gives GM's who fear that PC's might in the case of landing ships deploy their resources to easily planetside a good way to limit that impact. Only fools with addled brains will set down their starship in a swamp or on rocky uneven ground. And spaceports are easy to defend, a few batteries covering it would do the trick. If they would fail, there is always the option of mining the spaceport. A few plasma warheads exploding under the belly of his settling ship would ruins a Rogue Traders day.

The more I think about it, the better it sounds. Even if it is just to simplify the logistics of mass transport between planets. Would leave the GM and players more time for adventuring!

FvR

Also BFK states that any ship has several relatively large transports available. (1 per 5 space+4per cargohold).

Around 50 metres was once thrown around here.

So if said sloop isnt built like this vehicle carrier, but more like a 50 metre long and 20 metre wide Starship troopers dropship, you can easily fit close to a battalion (500 men) inside or a really tight fit of 15 tanks....(really, really tight without taking their mass into consideration)

That way even cruisers can get a quick refill of their supplies without being seriously hampered.

OTOH if we are talking huge warp capable ore barges, a planet landing would be far more efficient. Load everything up by trucks instead of loading trucks / containers into sloops.....

The small craft obviously retain their value and usefulness. They allow for great flexibility for all ships and give larger ships the chance to land elements or resupply themselves without being limited to space stations. But, this comes at a price, as it will take far longer to load or unload a ship a few tens of tonnes at a time as compared too directly transferring goods and people to or from the holds of a ship. To deploy troops or to trade in some low bulk-very high value produce this is a valid way of doing things, but it starts to groan when one starts to trade in promethium. Of course, the best solution is a space station that is served by the big system ships that are capable of transferring, say, the value of one cargo hold with every run to storage tanks on the station. Pump that in your Mass Conveyor, send the Conveyor too another space station above a planet where the promethium is needed and have system ships there transfer the stuff planetside. But lacking these facilities, that will only be availiable on civilised or very well developed mining systems, it will help a load if you can get your ship on a planet to fill it up with ores.

But, do we know of more and better clues that this is possible, or are there any elements in the game that refute this.

FvR

There are a few problems with landing a ship:

- Do your engines produce more thrust than the planets gravity ? The numbers given in the Rogue Trader books say yes for the main engine.

- Can your ship support itself in a way that points enough thrust in the right direction ? The main engines are on the back of the ship. If the ship were to land with them facing the planet, it means you have a large unsupported tower. Very likely to fall over, unless you have massive landing supports.

- When you land or takeoff, you will cause a lot of damage to whatever is underneath your landing site*. Is that much damage acceptable ?

- Can the ground support your ships weight, or will you sink into it ?

*If you have played Mass Effect 1, you should remember that near the beginning you looked over a large area of lava, with an NPC commenting that it must be where the ship landed. For Mass Effect, that much damage is reasonable. But Mass Effect has technobabble that reduces the effective mass of the ships, and ME ships are much smaller. So they cause less damage than if you could land most 40k ships.

However there is an upside to this damage: It doesn't matter how uneven the ground you attempt to land on is. When you land on it, you will make it flat.

As you point out, the first, third and fourth should be allright. The thrust of a spaceship is enormous, so that is no problem. The how to land might indeed be a problem, but don't forget that you have all kind of nice thrusters to steer you about in space, those help a lot, so the second might be allright, especially for 'smaller' ships. The third and fourth are mainly planet based. A decent spaceport should solve those in each case, whether it takes the shape of a massive ferrocrete platform towering over a fetid jungle or a vast plain carved from the bedrock of the planet.

Of course, the most obvious answer to technological questions is: This is Warhammer 40k! But I fully agree one needs a semi-technological support within the parameters of the system. So those are valid points.

FvR

Bilateralrope said:

40k technobabble, otherwise you stand no chance whatsoever.

The Plasmatroch a 40k warship puts out is easily larger than the craft itself. So even if you have the power necessary to land, any conventional method which employs the main drive is impossible. No one wants tp land his transport in a 3+ kilometre wide blast zone of pure lava.

I guess a huge amount of anti grav tech will play a large part in landing a transport or frigate safely.

Main thrust without any extra help.....just no. Unless you prefer your spaceport "well done" .

Well, each ship has a prodigious capacity to create artificial gravity....those plates are worked everywhere in the ship, basic Imperial STC (so advanced and so backward, the Imperium, gotta love it). That vast capability might be very well suited to support a planetside touchdown and might explain as well the size limit on landing.

FvR

Very Large Suspensors bolted to the spine of the ship when it is constructed. (enough to hold the ship up and together under gravity at sea level on a planet..., my postulation)

Anyhting larger than 3 kilometers is too heavy or spread out to work with IOM tech. (my opinion)

There. Problem solved.

The physics makes my brain hurt. So what's the final conclusion again?

HeavensThunderHammer said:

It's going to take a lot of specially designed equipment to land the ship, and if you attempt to land anywhere that isn't built for landing a ship, you are going to be landing in lava.

In the beginning of the Space Marine videogame you clearly see all kind of classes of starships engage each other in very low orbit, just a bit over the cloud-level, though I don't know if that game is considered canon.

It would seem however that it would be hard to find an area of raiders and frigates to set down on the surface of a planet since in most of the pictures of escort classes they have a fin or all kinds of weapon mounts etc, so if you would land an escort class vessel they would probably tip over.

Most transport classes do seem to have flat keel, judging by the pictures, so they would not suffer problems of tipping over. Their main problem will be projecting enough downward thrust for lift-off until they can engage their main engines.

One of the main arguments concerning which ships can or cannot land is also its design.

While most ships are perfectly designed for flight in space, where the structure does not have to "support" the ship's own weight, but most of them, especially the heaviest, would not be able to support a planet's gravity, they'd most likely collapse or at least be damaged by their own weight.

It is conceivable that transport / cargo ships, however big they may be, are specially designed with reinforced structural integrity when it comes to landing, at the expense of armor and weapons of course.

As someone stated earlier, thrust also is an issue, as is thermal shielding (entering a planet's atmosphere is REALLY hot ), and so on… So yes a ship would have to be designed for both, and clearly most capital ships (or even frigates for that matter) probably aren't. Low orbit, sure, Landing, most likely out of the question.

BFG stuff aside, I have a hard time seeing almost any 40k ship landing. Some could do so, but I do not think they could take back off without help. To me 40k voidships are not made to land…but some are made to survive an emergancy landing.

This question came up in my game a while back and I engineered some concepts that might not be completely canon might be functional.

Planetary Interaction:
- Planet Landing is restricted to Transports, Raiders, and Frigates
- Landing Ships are restricted to land at Space Ports that have at least an established Low Port
- Landing method is based on the mass of the ship, for each 5 Megatons of ship the ship needs 1 system ship tug to lead it into the planet landing zone
- The landing zones are specifically designed to support a specific amount of mass per square kilometer landing zone
- The landing zone platforms are Hive Structure style crawlers that transfer the ship into linear catapult style system that slowly starts accelerating around the world in question until they reach high orbit were the ship is released and allowed to move on its own power and when they leave orbit they activate the main engine.

The Planetary Tugs:
This are specialized Mechanicum System Monitors that have a rough mass of 5 Megatons that have oversized engines that can handle up to twice their mass and have supplemental thrusters to move in the atmosphere.

Player Owned Star Ports:

Star Port Charter
- Compact with Forge World
- Good Reputation with Mechanicum
- Ownership of location for Port

Star Port Core
- 20 Profit Factor sink
- 12 Structure Slots
- Benefit: +100 AP Trade Endevours

Star Port Power Station
- 5 Profit Factor sink
- (-1) Structure Slots
- Benefit: +5 Megatons Launch Capacity to MagLev Launch System

Star Port Landing Zone
- 1 Profit Factor Sink / Megaton a Landing Zone can support
- (-1) Structure Slots for Transports, (-2) Structure Slots for Raiders, (-3) Structure Slots for Frigates
- Benefit: Ability to land (1) ship of the specified ship class

Star Port MagLev Launch Facility
- 5 Profit Factor Sink
- (-1) Structure Slots
- Benefit: Ability to Launch (1) ship into High Orbit of the planet

Star Port MagLev Communication Uplink
- 5 Profit Factor Sink
- (-1) Structure Slots
- Benefit: Ability to Launch and Land (1) additional ship per month

Star Port MagLev Communication Nexus
- 20 Profit Factor Sink
- (-2) Structure Slots
- Benefit: Ability to Launch and Land (4) additional ships per month

this are just some of the things I worked with my players that you guys might be able to use.

I rather like this list. It also hearkens back to my thread regarding lifting bigger ships off of a planetary surface. I always found it odd that the book has the Planetbound for Millennia background (Into the Storm, I think), and numerous ships in several books, but none had a ship like the Tug, something that could haul a big wreck back up into space, or tow a station/station component through the Warp, to get it where it will be established. It made me sad, because if I were to find something worth salvaging, and wanted to get it, I'd have to make something up, when they had given so many other things to me.

As for landing ships on the planet, I'd say, overall it's not for Imperial ships. The scale of Imperium ships, compared to numerous other series, like Star Wars, is HUGE, and such bulky things would never get off the ground again. They would need support mechanisms of their own, to say nothing of the place they would land needing to be reinforced, and the area around it would be decimated by its efforts to take off, again. These ships are even built in space, for the most part, meaning they really weren't probably designed to need to escape gravity; they never have before. For your group to go down, a landing shuttle of a thing, or maybe a troop transporter would be necessary, or shell out the extra points for a teleportarium, if it can fit with your ship. Transports might be my cutoff point, as they are as their name implies, designed to move people or goods to other locales, but bigger ships should stay where they were born, and meant to live and die; the Void.

point taken and I agree but if the players want to land the ship well this are the guidelines and seems a happy medium of techno black box tech and narrative style gaming. Besides they have to pay for the privilege of landing the ship in the first place and making suh a heavy investment in the planetary infrastructure makes them bound to the location.