1g Ships and Size:7 worlds...
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AnotherDilbert
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Did he need to say that?
Now take off from the planet, while gravity press you down (red) more than the ship's drive can thrust (green):
You can't, you will stay put.
Note that it not really size, it's surface gravity that is the limit. They only coincide if the planets density is the same as Earth's.
Now take off from the planet, while gravity press you down (red) more than the ship's drive can thrust (green):
You can't, you will stay put.
Note that it not really size, it's surface gravity that is the limit. They only coincide if the planets density is the same as Earth's.
Enoki
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Wouldn't this depend on the design of the ship as well? If the ship can generate some degree of aerodynamic lift, then it could take off like an airplane and use that lift to offset some of the gravitational effects. All the ship has to do is not try to go vertical, instead climbing steadily until gravity is lower, or its speed is sufficiently high to overcome it.
mike wightman
SOC-14 10K
You mean like is shown for the typical Traveller ships? 
Type S, Type A etc are all shown as belly landers with m-drive "exhausts" pointing out the back, which to me indicates that they take off and land just like aircraft.
The thing is if you have a basic lifting body airframe and a constant thrust 1g engine with infinite delta V then you get to orbit just fine, all it takes is accelerating to 7km/s.
Type S, Type A etc are all shown as belly landers with m-drive "exhausts" pointing out the back, which to me indicates that they take off and land just like aircraft.
The thing is if you have a basic lifting body airframe and a constant thrust 1g engine with infinite delta V then you get to orbit just fine, all it takes is accelerating to 7km/s.
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AnotherDilbert
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Sure, with some atmosphere, wings and massive runways. I can perhaps see the Subbie or Serpent doing that.
A Free Trader, not so much...
Do most Traveller starships have wings, and do most starports have massive runways? There is no mention of it, only that Class E and X have nothing but a "bare spot of bedrock", that I take as no massive runway. I vaguely remember runways in a JTAS adventure?
If we don't have a dense enough atmosphere, atmospheric lift won't work all that well.
Look at the landing gear, they will roll really well down a runway (S7)?
So, can we use atmospheric lift to overcome the gravity well? Yes, with the right atmosphere, ship, and starport, sure. With any atmosphere, ship, or starport, as a general solution, no.
Baroun Tardis
SOC-12
And take a look at pictures of starports, with long runways.
T5 explicitly defines this stuff, talking about various options for ships.
Condottiere
SOC-14 5K
Landing wheels would need to be strong enough to compensate for the weight of the hull.
Note that skids tend to require local gravity neutralization.
Note that skids tend to require local gravity neutralization.
Enoki
SOC-14 1K
Even here, you have a grav system on the ship to lighten it. It only needs to be lighter than air (the atmosphere), like a balloon, to lift off. That would obviously need to be the case if you had 'feet' instead of wheels on the landing gear.
Once floating, you engage the maneuver drive. If you are producing mostly forward motion, the hull acts as a lifting body and the ship accelerates without trying to climb against gravity. Once at high speed, the ship could use that speed to climb into space trading velocity for altitude.
It works the same way displacement for ships and metacentric height does:
Metacentric height - Wikipedia
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He did early on...
Condottiere
SOC-14 5K
The potential for top heavy hulls to tip over increases.
I guess you could switch on the artificial gravity to local gravity plus whatever feels comfortable, and operate the spacecraft upside down.
I guess you could switch on the artificial gravity to local gravity plus whatever feels comfortable, and operate the spacecraft upside down.
AnotherDilbert
SOC-14 1K
What grav system?
The local gravity is added to the ship's vector, it's not optional; hence ships have no anti-grav drive by default.
Sure, we could build ships with anti-grav drives, like grav vehicles, but why would that be any smaller or cheaper than an M-drive? MT lets you do this, but it costs about the same: Why would you want 1 G grav drive + 1 G M-drive at the same cost as a 2 G M-drive?
AnotherDilbert
SOC-14 1K
Sorry for derailing your thread, but I haven't seen that said explicitly.
Heh, it happens.
Honestly I was looking for the quote, because I was mentally hammering on needing something beyond just a streamlined hull for successful planetary landings.
Enoki
SOC-14 1K
Then having a ship with 'feet' skids, or pads wouldn't be possible except for tail sitters that launch vertically. 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.
While it doesn't solve the problem of a 1G lifting off of a 1G planet. What I tried in Orbiter Space Simulator is to model a ship that had a m-drive for thrust, and a second m-drive mounted on a swivel that would rotate to point to the local gravity vector. The 2nd M-drive would negate the local gravity vector allowing thrust m-drive to be whatever size large or preferably small to get the travel time you want.
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.
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.
Condottiere
SOC-14 5K
If it wasn't too chancy, in theory you could overclock the manoeuvre drive.
Or if offered the option, use rockets to help boost lift.
Or if offered the option, use rockets to help boost lift.
Spinward Flow
SOC-14 5K
You have 1G of (total) thrust available to you.
Surface gravity is 1G+.
Can you "lift" off from that surface?
C'mon people ... this isn't rocket science ... (it's gravitics!).
I mean, the math works out to ... (1+) - 1 > 0 ... and you need to reach "less than zero" in order to Go To Space Today™.
For worlds with a surface gravity of less than 1G, you're fine.
0.9 - 1 = -0.1 = You Can Go To Space Today™
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).
Surface gravity is 1G+.
Can you "lift" off from that surface?
C'mon people ... this isn't rocket science ... (it's gravitics!).
I mean, the math works out to ... (1+) - 1 > 0 ... and you need to reach "less than zero" in order to Go To Space Today™.
For worlds with a surface gravity of less than 1G, you're fine.
0.9 - 1 = -0.1 = You Can Go To Space Today™
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).
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.
mike wightman
SOC-14 10K
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.
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.
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