1g Ships and Size:7 worlds...

[atpollard]

Any family resemblance to a Type A Free Trader or a Type S Scout?
WHERE ARE THOSE GIANT WINGS THAT ARE ABSOLUTELY ESSENTIAL!

 

[atpollard]

To my limited knowledge, jet fighters don't generally fall off the Earth to end up in orbit. There's a reason we still faff about with rockets to go to space?

Come on ... JET Fighters have AIR BREATHING ENGINES. How many 0.5G Thrust ROCKET POWERED FIGHTERS are there that could attempt to accelerate to orbital velocity and fly without AIR? The X-15 ROCKET powered Airplane DID reach space (July 1963).

(Not much wing.)

[Traveller Craft have 30 DAYS worth of Fuel to accelerate, so even 0.1 G horizontal acceleration x 30 days ... you do the math!]

 

[AnotherDilbert]

Striker specifies the STARSHIP is in ORBIT

A. Movement: The movement rate of a spaceship is determined in the same way as that for a grav vehicle; the ship's maneuver drive rating is used as its G value.

1. Grav Vehicle Maneuver Gs: A grav vehicle has Gs of acceleration equal to its thrust in tons divided by its weight, also in tons. One G is needed to keep the vehicle in the air (and if its thrust is less than one G, the vehicle cannot move); thrust in excess of one G is used for maneuver. Thus to find maneuver Gs, subtract one from the total G value.

The movement rate is determined as outlined in the vehicle design rules in Book 3, but instead of subtracting 1 from the G-rating of the vehicle's drives, the local gravity is subtracted instead.

"The vehicle cannot move" applies to spacecraft in a planetary setting. If it is landed it has a movement rating of 0, it cannot move.

A Scout with a 2 G drive, just like a grav vehicle with 2 G, has a max movement rating of 1200 km/h in 1 G gravity and 960 km/h in 1.2 G gravity. That does not apply to orbital speeds...

A Free Trader with a 1 G drive, just like a grav vehicle with 1 G, has a max movement rating of 600 km/h in 0.5 G, and none in 1 G, it cannot move.

I have no idea why you think Striker does not apply to planetary surfaces.

... that is what keeps frustrating me about your references to Striker when discussing the LBB2 Combat Vector Movement. You are IGNORING the clearest STRIKER RAW of all ... Striker does not apply to a 1G ship on a size 8+ world! Striker says a Grav Vehicle (Grav Tank, G Carrier, Air Raft) cannot move.

Striker very explicitly explains how spacecraft moves on a worlds surface, just like grav vehicles.
You just need available thrust > weight to land, move, or fly. Just as LBB2 would suggest:

3. Thrust: Maneuver drive thrust is measured in Gs (gravities) expressed as a vector of both length and direction.

Maneuver drive uses thrust to accelerate a ship in a specific direction for a specified distance.

Acceleration involves altering a ship's vector by adding another to it; this new vector can come from thrust using the maneuver drive, or it can come from gravity.

It's just thrust and Newton, not magical unicorn farts.

MT and FF&S (written by the Striker Gang to expand Striker to Starships) explains that Grav Vehicle "Drives" are different than Starship "Drives" [that whole deep space vs need planetary mass thing].

MT isn't CT; Thruster plates are a development on grav modules with additional techobabble. Movement rating (on the surface of a planet) for spacecraft is still the same as for a grav vehicle. Both are of course just thrust:

The second major breakthrough is artificial gravlty. Created by manipulating subatomic forces, artificial gravity is not anti- gravity but is instead a unique force that acts upon the natural gravity field created by all matter.

The fourth significant development came from the search for a starship maneuver drive that did not lose efficiency when away from a strong gravity well. Artificial gravity and damper technology led to yet another sub-atomic force-based technology. This new, artificially generated force pushes against a vessel's "thrust plates" themselves, which make true reactionless thrusters a reality for starship-sized vessels.

FF&S explicitly uses the same drive systems for grav vehicles and spacecraft, contra-grav and HEPlaR in combination. See e.g. Air/raft (TNE, p363) and Free Trader (TNE, p368).

 

[AnotherDilbert]

Any family resemblance to a Type A Free Trader or a Type S Scout?
WHERE ARE THOSE GIANT WINGS THAT ARE ABSOLUTELY ESSENTIAL!

They are also very light, and didn't take off from runways. They were lifted to altitude and speed, before they tried to fly.

The X-24 had an effective "wing area" of 31 m² for a mass of 6 tonnes.
Recalculated to Free Traders that is ~10 000 m² "wing area" needed, slightly more than the about ~500 m² it has.

The Free Trader also need to land and take off in potentially VThin atmosphere (~10% of Earth standard), so would need a much bigger wing.


If you want to ignore all the practical details, go right ahead, it's your game. (It would just be a house rule...)

 

[atpollard]

FF&S explicitly uses the same drive systems for grav vehicles and spacecraft, contra-grav and HEPlaR in combination. See e.g. Air/raft (TNE, p363) and Free Trader (TNE, p368).

You are either unfamiliar with FF&S or being deliberately argumentative.
TNE CHANGED the paradigm and included rules for other options (including the previous REACTIONLESS DRIVE of Classic Traveller & MegaTraveller). In either case ... I quit ... you win (because I certainly don't feel like a "winner" continuing this discussion any longer).

 

[AnotherDilbert]

Come on ... JET Fighters have AIR BREATHING ENGINES. How many 0.5G Thrust ROCKET POWERED FIGHTERS are there that could attempt to accelerate to orbital velocity and fly without AIR? The X-15 ROCKET powered Airplane DID reach space (July 1963).

It was launched from aircraft, and didn't ever remotely achieve orbit.

It did reach 100 km altitude and 2 km/s speed, far short of sustained orbit.

To reach orbit it would have to achieve orbital speed in atmosphere, as outside the atmosphere it would have no aerodynamic lift, but have to counter gravity with drive thrust.

In atmosphere speed is limited by drag, so no unlimited acceleration for weeks on end.

Orbital speed would be in the region of Mach 20-30, somewhat problematic to achieve, as discussed earlier in this thread.

 

[AnotherDilbert]

You are either unfamiliar with FF&S or being deliberately argumentative.
TNE CHANGED the paradigm and included rules for other options (including the previous REACTIONLESS DRIVE of Classic Traveller & MegaTraveller).

It had rules for Thruster plates, but not anti-gravity, although they were discussed together:

FF&S, p73: Maneuver drives in previous editions of Traveller were explained as related to the same body of theoretical physics which allowed artificial gravity and damper fields, which is to say manipulation of gravitational force and the strong nuclear force. Artificial gravity was defined as a force which could either push or pull and which acted on the gravitational field of a mass.
Clearly, this would not be an efficient means of travel outside of a gravity well, and so a further advance was postulated which allowed the force generated by the drive to push on the actual thruster plates of the ship itself, propelling it through space and achieving a true reactionless drive.

Design: Thruster plate technology becomes available around tech level 11 (due to the fact that it is tied closely to many of the other theoretical breakthroughs that occur at about that time). Each cubic meter of installed thruster plate drive generates 40 metric tonnes of thrust, masses 2 tonnes, requires 1 MW of power, and cost MCr 1.

Thruster plates (regular M-drives), generates thrust. Just as in CT and MT.
Anti-gravity was said to be a force (thrust), just like in CT and MT, but not specified as an engineering system.


Classic anti-gravity is different from TNE contra-gravity.
Anti-gravity is thrust.
Contra-gravity is described as buoyancy, but not specified exactly.


But, sure, after writing a spreadsheet for TNE spacecraft, including both HEPlaR and classic thruster plates, I'm clearly unfamiliar with TNE...

 

[mike wightman]

X-15 19 m² for a mass of 15 tonnes.

 

[AnotherDilbert]

X-15 19 m² for a mass of 15 tonnes.

Yeah, that is better, about 2500 m² per Free Trader.

It also had a thrust of 313 kN for a mass of 15 tonnes, i.e. a 2 G drive.

 

[Condottiere]

This is Classic, but veering off for a moment.

We take a fourteen hundred cubic metre unpowererd boat chassis, which apparently could be built from fibreglass or aluminium, or wood, at sixty thousand credits.

Install a factor one manoeuvre drive, jump drive, reactor, bridge and fuel tank; plus some miscellaneous stuff like airlocks.

It floats, maybe levitates.

 

[Grav_Moped]

This?

36 m² wing area for a mass of 24 tonnes, or 3000 m² per Free Trader.


Did you mean the F-104 Starfighter, the Widowmaker, the Lawn Dart?
18 m² wing area for 13 tonnes MTOW, or ~2800 m² per Free Trader.

Not very remarkable?


The Concorde used 360 m² for 185 tonnes, or 3900 m² per Free Trader. Not so different.

Reaching way back (I'm going through my old posts) and upvoting just for mentioning the F-105. Gotta love it -- designed as a supersonic tactical nuclear bomber, only actually used as a subsonic bomb truck.

 

[Spinward Flow]

just for mentioning the F-105.

Ah, but to get the TRUE XP for the "Thud" ... you need to HEAR it when it flies by!

 

[Grav_Moped]

Ah, but to get the TRUE XP for the "Thud" ... you need to HEAR it when it flies by!

Used to be one on up on a stick where I worked (but it's been re-positioned a bit since I retired). There's another in the museum next door...

ETA: Apparently there are two in the adjacent museum (a D model and a G model).

 

[Ulsyus]

The cost of adding an 0.25G anti-grav drive may be lower than the cost of adding 1G to the M-Drive capability (to the point it might be incorporated in hull streamlining cost, perhaps). It might not show up in the context of LBB2 combat since that system uses integer Gs, and the 0.25G gets rounded away (down) for simplicity.

Just tossing in a potential handwave option.

BBB2 p104 lists TL stage effects and efficiency increases for drives, which could be a simple way to explain marginal increases in drive capabilities in order to achieve escape velocities

 

[AnotherDilbert]

To use T5 Stage Effects you would have to build the drive at several TLs higher, so a TL-9 Free Trader would need a TL-13 1.3 G drive at three times the cost.

Standard: MCr 4, 100 EP (≈G-tons of thrust):


Ultimate: MCr 12, 130 EP (≈G-tons of thrust):


I suspect that would be less than optimal...

 

[Ulsyus]

To use T5 Stage Effects you would have to build the drive at several TLs higher, so a TL-9 Free Trader would need a TL-13 1.3 G drive at three times the cost.

Maybe we're working off different editions. In the stage effects table (T5.10 BBB2 p76) it's possible to build an Improved drive at TL+1 that has 110% efficiency, so that'd do the job.

Plus, if I had to I'd just increase the size of the M-drive unit so that it in effect produces more thrust (a 1.1 or 1.2G unit) by increasing the various costs by that much (A class M-drive being 2.1 or 2.2dTons as per the BBB2 p77). Much simpler, and possibly following the Engineering Rule of Thumb. (see what I did there?)

 

[AnotherDilbert]

Maybe we're working off different editions. In the stage effects table (T5.10 BBB2 p76) it's possible to build an Improved drive at TL+1 that has 110% efficiency, so that'd do the job.

Sure, that would get us off a 1 G (size 8) world, but not a 1.1+ (size 9+) world. 1.3 G would get us off most size A worlds.

Plus, if I had to I'd just increase the size of the M-drive unit so that it in effect produces more thrust (a 1.1 or 1.2G unit) by increasing the various costs by that much (A class M-drive being 2.1 or 2.2dTons as per the BBB2 p77). Much simpler, and possibly following the Engineering Rule of Thumb. (see what I did there?)

Agreed, but the disadvantage of the lettered drive table is that it does not generally allow it...
We can easily reverse engineer the drive table formulae (in T5), and make any drive of any desired size, it would just be a house rule?

 

[Ulsyus]

Sure, that would get us off a 1 G (size 8) world, but not a 1.1+ (size 9+) world. 1.3 G would get us off most size A worlds.

I was just using those in an illustrative way, of course a full spectrum of options would be needed.

Agreed, but the disadvantage of the lettered drive table is that it does not generally allow it...
We can easily reverse engineer the drive table formulae (in T5), and make any drive of any desired size, it would just be a house rule?

I suppose it comes down to where on the games<>simulations spectrum you see YTU sitting. I know I won’t be sweating it much: this is meant to be fun!

 

[Dragoner]

Just use the table for times, if one had the actual mass of the ship you could figure more exact; real world it would be fuel limited (fuel as payload) though traveller skips over that.

 

[Ulsyus]

Just use the table for times, if one had the actual mass of the ship you could figure more exact; real world it would be fuel limited (fuel as payload) though traveller skips over that.

That’s exactly why we shouldn’t get too wrapped around the axles about this!