mike wightman
SOC-14 10K
If you can generate aerodynamic lift to gain altitude and velocity once airborne then you can generate enough forward velocity with a 1g engine to generate enough lift to take off in the first place.
CT Only: Big Far Trader (Type R2)
- Thread starter Grav_Moped
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Proneutron
SOC-13
What happens when the atmosphere gets so thin at altitude that lift is no longer generated but the gravity is still pulling your 1G ship downward with 2Gs of acceleration?
It's not pulling 2G down. The highest gravity you'll see in normal worldgen is 1.2G (Size 10).
AnotherDilbert
SOC-14 1K
If you have to roll for it, you can't do it routinely, otherwise starports will be studded with crashed ships and mortgages will be a lot more expensive...
The movement rules in LBB2 says that ships are affected by gravity, without any extra thrust...
Sure, in atmosphere, but streamlining in CT does not necessarily imply aerodynamic lift. It can perhaps, but most standard ships like the Free Trader are just rounded bricks. E.g. MT has Airframe as a more expensive configuration.
Proneutron
SOC-13
Okay. What happens when you run out of atmosphere and your 1 G ship is being pulled down by 1.2G? Orbital velocity would be 35.74 km/sec. You aren't going to get that with all that induced drag and 1 G of acceleration. I don't think. And how do you get off the ground at all on an airless world?
mike wightman
SOC-14 10K
You accelerate horizontally at an altitude that grants lift until you achieve orbital velocity - easy as that.
Condottiere
SOC-14 5K
Overclocking the drives can trade time for additional bonuses, and there are options to accumulate more.
And if it lasts only six minutes, is that six minutes is enough to slip the surly bonds of earth to touch the face of God.
And if it lasts only six minutes, is that six minutes is enough to slip the surly bonds of earth to touch the face of God.
Atm=2D-7+Size.
If Size=9, Atm has to be at least 2; if 10, at least 3. Both of those are "very thin", and there's only a 1:36 chance of it being that, with the average at 9 or 10 (Dense or Exotic).
Orbital velocity (LEO) for size 8 (Earth) is 7.8km/sec. Gravity at LEO (2000km altitude) is about 0.9G. I agree that getting much aerodynamic lift above 30km altitude will be difficult, but as long as lift/drag is higher than 1 (size 8) through 1.2 (Size 10), there will be lift until aerodynamic drag starts to taper off. At that point the flight profile is basically skipping along the lower boundary of the thermosphere (~100km) to build velocity.
I can see issues with hypersonic skipping over some of the weirder atmosphere types -- ultra-hot hull material and corrosive air? Not good.
Proneutron
SOC-13
No, because the induced drag will prevent you from obtaining orbital speed while in atmosphere.
Proneutron
SOC-13
An SR-71 pilot told me that the bigger problem they had was control at that altitude. You can easily start tumbling uncontrollably as your control surfaces lose lift. I would require Aircraft pilot skill in addition to spacecraft pilot skill to pull it off
So it needs to be a lot lower than hitting 8+, at least for enough extra power to get clear of a Size 8 world. Size 9 should cause some anxiety even if there's not a lot of actual risk. Size 10 ought to be scary.
Probably something like:
4+ on 3D, +DM Engineering for size 8 (215:1 without +DM, guaranteed if any +DM),
5+ on 3D for Size 9 (same DM) (108:1 without +DM, 215:1 with +1),
5+ on 3D for Size 10 (but +DM is Eng/2, round down).
Agreed. On a Size 8 world, 1G just lets you hover indefinitely. Seems a bit silly; someone could tow the ship into an updraft if needed.
Yeah. Traveller as depicted in the OTU is cinematic SF rather than realistic, though -- if it looks streamlined enough, it'll fly due to the Rule of Cool. Except in MT, where streamlined isn't airframe unless called out specifically (and paid for).
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It's got grav drives that can spin the ship fast enough to sometimes prevent laser burn-throughs. Stability should be a moot point.
But to your point, look at the NF-104 (wiki), an F-104 with reaction control thrusters; it was built to zoom-climb (with rocket assist) above the altitude where aerodynamic control surfaces work...
The X-15 had them as original equipment.
Condottiere
SOC-14 5K
Solid Rocket Boosters are TL-7. Kinda spendy, though.
Proneutron
SOC-13
Really? That's not in the rules. (which include reaction jets) Aside from house rules you have a problem with control in this scenario.
Implied by the "batteries bearing" rule in HG, but it's probably just my interpretation. Any ship to 19,999Td can present all of its weapons, wherever located, to an adversary for long enough to inflict damage, within a 20 minute turn. Since it's not an issue in LBB2 combat, this must also be true in a 1000-second (17 minute) turn.
More to the point, it's quite similar to the flight profile used in skimming gas giants for fuel, which even partially streamlined ships can do with very low risk.
If you look at movement rules, it's basically fundamental that a lower G drive isn't getting you out of trouble.
The other "gorilla" in the room, is not necessarily planets, but starts. Here we're talk 2, 3, and 4G areas of influence. Definitely trouble.
Proneutron
SOC-13
Ya that's not really what it is about. The ONLY out rule wise I know of is MTs Spaceship Operations manual about Thruster plates being able to be "over driven" to blast out of a higher G planet than the M drive rating. But that doesn't apply to MgTs Grav drives. Different Tech. These are parts of the rules that should be fleshed out a it would take a very short time to write them. Otherwise it leaves it different in each game
If Cold War air forces could devise JATO units for airplanes, why couldn't dangerous starports (hi-G, with or without lo-atmosphere) have some sort of "grav-assist" units to add power for takeoff. Another example would be various assist-rockets on first-stages of rockets. I know both the Soviets and NASA used them in various configurations.
At many "civilized" starports, of course, ships that could not safely take off under their own steam would simply be required to get no closer than orbit. That's why they have shuttles and pinnaces and such for rent!
At many "civilized" starports, of course, ships that could not safely take off under their own steam would simply be required to get no closer than orbit. That's why they have shuttles and pinnaces and such for rent!
AnotherDilbert
SOC-14 1K
A decent Engineer makes that no risk.
I would make it perhaps 12+ on 2D (no DMs) to have a problem, then another 2D roll with DMs to see how serious/what problem.
That way it is always a risk, but lower risk with a good Engineer.
