1g Ships and Size:7 worlds...

[infojunky]

This is why I maintain that a 2G maneuver drive is all you need to VTOL on "most" mainworlds (there will be occasional rare exceptions).

Heh, this was the genesis of this entire thread. A excuse to rewrite the classic Streamlined ship with 2g thrust instead of 1g.

 

[AnotherDilbert]

Then having a ship with 'feet' skids, or pads wouldn't be possible except for tail sitters that launch vertically.

MT SSOM has a really convoluted explanation of how this works.

One would think that the same grav system that provides the artificial gravity for the crew in space could be used to overcome planetary gravity on the ground. At least, that's my thinking. It's the same way grav vehicles work. This would not be sufficient for much in the way of vehicle thrust, but it would have to be present to give the ship artificial gravity.

Also given the technology behind grav vehicles and air/rafts why not say that grave plates are part of the m-drive system. Allowing 1-G ships to take off of high G worlds. Since we are talking about different types of handwavium anyway.

Since ships are TL9 I would imagine their streamlined hulls include computerised control surfaces that grant them greater aerodynamic properties in a similar way to how 5th and 6th generation aircraft today require computer assistance.

Yes, if you really want all ships to be able to land on all worlds, just wave the Referee-wand and say that it works. You don't have to make all that complicated hand-waves. Just say they have T5 "lifters" ≈ T4 contragrav, and your ships can float happily, perhaps with a slight buzz.

It just wouldn't be LBB2 that says it, but your house rule.

 

[Grav_Moped]

So the vast majority of planes can't take off.

And yet Starports are shown with runways, streamlined ships are belly landers and there are illustrations of some with landing gear.

A 1g continuous thrust engine is going to achieve a ground speed that will allow the ship to take off. Once in the air lift and weight are balanced so you can continue accelerating at 1g until you get to the 7km/sec orbital velocity.

Since ships are TL9 I would imagine their streamlined hulls include computerised control surfaces that grant them greater aerodynamic properties in a similar way to how 5th and 6th generation aircraft today require computer assistance.

The vast majority of planes are not VTOL.

The stall speed of lifting-body aircraft, especially with the surface (wing) loading of typical Traveller spaceships, is non-trivial. Landing gear for aircraft massing as much as typical Traveller spaceships, are also non-trivial -- and quite unlike those typically depicted for such spaceships.

At an assumed mass of 10 tons per Td, a Type A Free Trader would weigh 2000 tons. This is about 4.5 times as heavy as a Lockheed C-5 Galaxy...

 

[Dragoner]

That is pretty dense, I have read it should be somewhere in the range of 250-300kg/m^3; personally I make it 3.5 tons mass a dimensional ton.

 

[Condottiere]

You can use the millipede option, turn the entire bottom into a mass of tyres.

 

[Grav_Moped]

You can use the millipede option, turn the entire bottom into a mass of tyres.

Yeah, but tires make for substandard ablative heat shielding.

 

[AnotherDilbert]

That is pretty dense, I have read it should be somewhere in the range of 250-300kg/m^3; personally I make it 3.5 tons mass a dimensional ton.

In the editions that keeps track of mass, it's generally about 10 tonnes/Dton, e.g. MT Free Trader:

 

[Condottiere]

 

[kilemall]

In the editions that keeps track of mass, it's generally about 10 tonnes/Dton, e.g. MT Free Trader:
View attachment 3466

Does that float?

Playing around with this buoyancy calculator, yes.

Buoyancy Calculator

Buoyancy calculator finds the buoyant force acting on an object immersed in water.

www.omnicalculator.com

But if you carry water or other heavier fuel instead of hydrogen, have higher gravity and/or different ocean fluid then water, maybe not.

 

[AnotherDilbert]

Does that float?

Simplified, as long as density is less than 1 tonne/m³ (13.5-14 tonnes/Dton), yes it will float in water.

So a 200 Dt ship (MT: 2700 m³) will float if it has a mass of less than 2700 tonnes. At ~2300 tonnes, it should float, with most of the ship under water.

In general unarmoured ships will float, heavily armoured ships will not.

 

[kilemall]

The vast majority of planes are not VTOL.

The stall speed of lifting-body aircraft, especially with the surface (wing) loading of typical Traveller spaceships, is non-trivial. Landing gear for aircraft massing as much as typical Traveller spaceships, are also non-trivial -- and quite unlike those typically depicted for such spaceships.

At an assumed mass of 10 tons per Td, a Type A Free Trader would weigh 2000 tons. This is about 4.5 times as heavy as a Lockheed C-5 Galaxy...

High tech tires then.

 

[Grav_Moped]

High tech tires then.

Catapult launches, from launch sleds/cradles.

Landing on water, with floating drydocks positioned for recovery to the launch cradles.

Armored ships don't float, but ships that are armored typically have more than the minimum M-Drive so it's not an issue.

But as I've said before, if it's my ship, I'm not putting it into a gravity well that I'd need someone else's help to get it back out of. I'll haul cargo up and down 4 tons at a time in an Air/raft, first.

 

[Enoki]

In the early days of aviation, one way to get a really big and heavy aircraft aloft was use a seaplane...

If the ship is shaped correctly, and has the displacement to float, you have a seaplane and lots of 'runway,' well most of the time assuming that the world has bodies of water...

 

[Condottiere]

And flying boats.

I think the difference is when the primary hull meets the water.

 

[Grav_Moped]

In the early days of aviation, one way to get a really big and heavy aircraft aloft was use a seaplane...

If the ship is shaped correctly, and has the displacement to float, you have a seaplane and lots of 'runway,' well most of the time assuming that the world has bodies of water...

Much of that was because long paved runways weren't common, and variable-pitch props weren't up to it (or, early on, hadn't been invented yet).

And flying boats.

I think the difference is when the primary hull meets the water.

Start incorporating hydroskis in the landing gear (Convair F2Y Sea Dart) and shaping the ship's underside as a planing hull, and it starts getting expensive and inefficient.

 

[Condottiere]

There are enough science fiction books where they mention landing in the water, but I think the issue is more a question id the spacecraft are suited to land dirtside, and if the landing areas have suitable infrastructure.

I think, also, this is where wilderness landing is relevant.

Landing in the water is basically floating on a fuel source.

However, I suspect most planetary authorities want to control migration, and customs, so you're probably forced to land on specific landing strips.

Also, that controls fuel supply.

 

[Grav_Moped]

There are enough science fiction books where they mention landing in the water, but I think the issue is more a question id the spacecraft are suited to land dirtside, and if the landing areas have suitable infrastructure.

I think, also, this is where wilderness landing is relevant.

Landing in the water is basically floating on a fuel source.

However, I suspect most planetary authorities want to control migration, and customs, so you're probably forced to land on specific landing strips.

Also, that controls fuel supply.

In general, you'd want to land on solid surfaces, if only to facilitate boarding and cargo transfer. As used here, it's about enabling landing at high airspeeds and sink rates, by spaceships that don't have room for the landing gear that such landings would require. In the general case, I can see landing ponds for very large spacecraft whose landing gear would otherwise have excessive ground pressure for most paved surfaces.

 

[Grav_Moped]

I'm thinking you need something like a tank catapult...

... to tip the ship vertical. Then overload the maneuver drive by 30% for a few minutes to get a few km altitude, tip forward a little to gain lateral velocity, then flop over into a steep dive to get above stall speed and swoop out of it.

The drives can't handle operating in overload mode long enough to make a difference in space combat, just for long enough to pull this maneuver off.

(The mechanism is actually a tilt table, used to measure things like center of gravity and test the vehicle's functionality when tilted. But that's not nearly as funny...)

 

[Condottiere]

 

[atpollard]

Skids are no problem if you have enough Vaseline to coat the runway.