AnotherDilbert
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Sorry, flying a compact several thousand tonne brick on willpower alone isn't in my "suspension of disbelief" range...The idea here is to get within "suspension of disbelief" range. This is science fiction, after all.
1g Ships and Size:7 worlds...
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Mass tonnes. Weight tons would be significantly less, after applying the maneuver drive. Yes, you can't do both at once -- the idea is to do them sequentially.
AnotherDilbert
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We are deep into speculation territory. How much can we vector our thrust? Is the thrust the same magnitude off-center?
Presumably it isn't totally freely vectorable, as we would normally turn over to decelerate?
None of it is defined, unless we use SSOM from MT.
AnotherDilbert
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With a lifting body we are still over a factor ten off in a standard atmosphere, but to land under most conditions we have to be able to land in a thinner atmosphere, perhaps down to 10-20% of Earth standard. How much more lift would that require? Ten times as much wing area?
That would make us a factor hundred off needed lift?
Baroun Tardis
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Can you tweak that square meterage by using the hull itself as a lifting body?
Spinward Flow
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Can anyone point to a CT LBB that specifies starships have lifting body lift vectors added to their movement?
Is a stall speed mentioned? Because last I checked, lifting bodies tend to have stall speeds that are well above zero ...
And hilariously enough, a lifting body is only "useful" as a "contra to gravity" thrust source (of adequate vector magnitude) in a limited range of atmosphere types ... while an "excess of gravitic capacity" works everywhere regardless of atmosphere.
Well, you'd honestly want 1.4Gs to deal with Size: A and Atmosphere: 6-9.
Atmosphere: A+ and things just start getting ... weird.
Best to have a 2G maneuver drive and just not need to worry about terrestrial landings and liftoff, because you can VTOL onto any planetary surface (aside from the most exotic/absurdly high gravity ones).
Captain_Ahab
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why trace?
iirc, a world with a trace atmosphere can be no bigger than size 6, RAW, so the question of a 1g ship taking off becomes moot
1g worlds kind of implies a likely earth-like pressure and density
trace atmosphere would be like an altitude of 150,000ft on earth, I think, depending on temp and the atmo's molar mass
and the values would describe a ship far different from what the game's art suggests
m-drives were originally fusion torches which could also be used as weapons, so no magic anti-ionization fields
I say that a 1g ship can't land on a size 8 world, and has to rely on some form of interface craft
it is more interesting that way, anyhow
could be why scouts are 2g ships instead of 1g
mike wightman
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trace as in altitude based trace.
Free Traders land just fine, and take off too
Beltstrike has rules for fuel used as you use the m-drive - the LBB2 77/Hg 79 model and also has the anti radiation effect.
So energy weapon exhaust m-drive that also produces an anti particulate radiation screen
Free Traders land just fine, and take off too
Beltstrike has rules for fuel used as you use the m-drive - the LBB2 77/Hg 79 model and also has the anti radiation effect.
So energy weapon exhaust m-drive that also produces an anti particulate radiation screen
Ok, sports fans, I did start this thread looking for a quote from Marc in the early days.
Which was the intro into the idea that 1g ships were limited to landings on size 7 worlds or less. With the idea that a general purpose freetrader would both be streamlined and have 2g worth of manuver. For the broadest range of trade functionality.
Look at it this way, i was looking for a broader range of performance with thrust and streaming being reasons.
Consider “partial“ streamlining, which could describe a 1g ship that is streamlined.
Just ideas to play with.
Which was the intro into the idea that 1g ships were limited to landings on size 7 worlds or less. With the idea that a general purpose freetrader would both be streamlined and have 2g worth of manuver. For the broadest range of trade functionality.
Look at it this way, i was looking for a broader range of performance with thrust and streaming being reasons.
Consider “partial“ streamlining, which could describe a 1g ship that is streamlined.
Just ideas to play with.
RAW, there are no GIANT WORLDS without atmosphere … so that is actually a non-issue.
MegaTraveller took the Striker concept and ran with it … actually drawing a parallel between STREAMLINING classifications for starships and equivalent AIRFRAMES on aircraft (along with allowing STOL, VTOL and WATER landing options for Starship designs). While definitely NOT CT RAW … it is as close to the CT RPG as the Striker MINIATURES rules are to a RPG.
Captain_Ahab
SOC-9
assuming air density of .125 kg/m^3, a cross-section area of ~300m^2, a very generous Cd of .05, and 1g thrust ( 20,000,000 N, assuming a ship's mass of 1dton = 10 tonnes )*trace as in altitude based trace.
Free Traders land just fine, and take off too
Beltstrike has rules for fuel used as you use the m-drive - the LBB2 77/Hg 79 model and also has the anti radiation effect.
So energy weapon exhaust m-drive that also produces an anti particulate radiation screen
in a trace atmosphere, a Beowulf class Free Trader can maintain a speed of a little over mach 13
*by comparison, an F-104 Starfighter has a Cd = ~.048 and ~70,000 N thrust
I say no
<shrug>
It won't matter for most RAW generated worlds anyways and it puts up an interesting barrier for players to overcome
And that is one of the major failings of MT.
In that Striker is internal consistent with itself. But not with Traveller as presented before it. In that all the kludges to make it work with Traveller are very wonky.
Sure LBB2 but LBB5 can certainly be specced that way, given it’s a percentage based system.
Maybe there are a class of custom ships that cover the land anywhere niche market below 2G.
BTW been wrestling with the hot reentry issue. Thinking plasma weapon surface damage, beyond a certain point it goes spinal/nuclear level. Streamlined avoids a certain amount, armor reduces it as well, hull type indicates cross section value, partially streamlined takes more damage and non streamlined burn up on anything short of the 100kph air/raft type landing.
But of course past a certain speed it doesn’t matter, kinetic impact is impact if you can’t stop short of the surface or dense atmosphere.
Keep in mind that RL reentry value is already going up, we recovered that 7G comet probe and of course modern hypersonic missiles are pushing the envelope.
Yeah. Parachute recovery for a typical ACS ship is... let's just say, slightly implausible.
Not according to the rules as written, which only address Gs in integer increments.
Spinward Flow
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Why are you assuming that atmospheric entry would need to be "hot" with a Traveller maneuver drive?
It's only "hot" if the only way to reduce your velocity vector is through aerobraking/atmospheric drag (to save fuel).
However, if you've got "functionally unlimited delta-v" courtesy of a maneuver drive (that can run continuously for weeks) ... there is no "need" to use aerobraking to convert velocity into kinetic energy hot plasma due to friction.
With gravitics, you can simply VTOL ... from orbit to ground ... meaning that "geosynchronous" can be anywhere from the surface to to beyond the inertial orbit that is geosynchronous at zero thrust. Use your maneuvering power to slow down above the "atmospheric heating" radius until you're essentially "hovering" over the location you want to land at ... and then just dial back on the gravitics so you can SINK down towards the planetary surface in a controlled way using your gravitics.
It the classic case of "stop then land" versus the default of "land then stop" ... except that the "stop to hover" maneuver is happening at a MUCH HIGHER altitude.
If you're using your maneuvering power to "geosynch hover" before slowly descending into the atmosphere, you aren't going to experience much atmospheric heating at all on your way down. You can even control your descent to be subsonic the whole way down, if you want ... as opposed to making a hypersonic atmospheric entry for a pure aerobraking deorbit to ground.
Straybow
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I derived it somewhat differently, looking at drag racing to understand the relationship between power and acceleration. It isn't linear because
P = F·v = m·a·v = m·a·a·t, for which we assume a δt of 1.
For drag racing, top performance follows closely to P = g²·650 hp/ton. Top fuel dragsters (that weight just under a ton) are around 10-11k hp, with initial acceleration of 5g and average quarter-mile acceleration of 4g. P = 4²·650 = 10400 hp, fits pretty well. For you guys who don't use freedom units that would be roughly P = g²·480 kW/ton in System Inimical.
By way of reality check, the same method calculates a top speed for my 283 hp minivan as 114 mph. I have no desire to test this, but it seems plausible.
This is used to calculate an effective power for a desired acceleration. However, for grav tech it is assumed that acceleration is the controlling parameter. It doesn't apply a fixed force for any mass, which would result in higher acceleration below full load. Instead it allows the given acceleration up to the design mass, above which performance would degrade by some math that can't be derived with our current understanding of grav tech. I.e., somebody has to make that part up. It would probably use something like a moment of inertia for the mass distribution. I lean towards [m/m0]^5/4 as a simplification.
Then you have to decide what full load is, so I used 8 tons empty and applied a load of 32 tons. The 26-foot box is approximately 1/3 larger than TEU, which grosses 24 tons max. The 8 ton empty grav vehicle assumes a more rigid structure than the 6 ton empty ground vehicle, since it may have to endure greater forces of aerial maneuvers (banking, climbing, diving).
Condottiere
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1. Brute force would push a spacecraft through water to achieve lift.
2. Going lateral to the gravitational plane with a lifting body is trying to finesse that ocean of gas to get that lift where brute force alone would be insufficient, or is insufficient.
3. Otherwise, you could go straight up.
4. So you'd want to get atmospheric lift to the point gravitational influence drops to ninety nine percent Terran norm.
5. After that, it's just a question of circling the Equator and increasing altitude.
6. Dropships would more likely use retro rockets, the parachute making up the difference between Terran norm and over.
2. Going lateral to the gravitational plane with a lifting body is trying to finesse that ocean of gas to get that lift where brute force alone would be insufficient, or is insufficient.
3. Otherwise, you could go straight up.
4. So you'd want to get atmospheric lift to the point gravitational influence drops to ninety nine percent Terran norm.
5. After that, it's just a question of circling the Equator and increasing altitude.
6. Dropships would more likely use retro rockets, the parachute making up the difference between Terran norm and over.
AnotherDilbert
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