Streamlining

[Easterner9504]

To operate in atmo TRAV ships need be streamlined and of certain aerodynamic shapes. However at some point it seems a lot of people decided ships would have contra-gravity maneuvering capability ala floating cities.

Based on this I see no reason why semi-streamlined could not operate in atmo. Has this ever been discussed aka beaten to death in the past?

Conclusion reached?

 

[aramis]

Essentially, the camps can't come to resolution, and the system mechanics neglect landing gear.

 

[far-trader]

Has this ever been discussed aka beaten to death in the past?

:rofl: Many times

Conclusion reached?

Inconclusive. Divided.

Personally I figure "streamlined" includes a lot of things beyond the shape of the hull. Like retractable and covered bits that would be worn, melt or snap off in atmo. Like landing gear to actually land. Like structural components to actually keep the ship from sagging or bending under atmo and or gravity loads.

I also don't think CG will allow you to float down into an atmo from vacuum without any worry about wind shear and heating from friction. Basically even with CG (imo) it's still a hot entry into any atmo.

 

[robject]

I also don't think CG will allow you to float down into an atmo from vacuum without any worry about wind shear and heating from friction. Basically even with CG (imo) it's still a hot entry into any atmo.

I tend to agree what those sentiments. Reentry with CG ain't just a vertical landing like a Harrier does. Could just be the thing which ensures that you're at velocity Zero just before you hit the ground, though you could well be ballistic in earlier stages of reentry.

 

[Brian Smaller]

I don't allow unstreamlined ships to enter atmospheres. Partially streamlined ships can but I basically double the time it takes to get frmo surface to space and vice versa.

 

[Frankymole]

A lot of the rules sets also differentiate between "streamlined" and "airframe" hulls - streamlining doesn't allow one to fly around like a 'plane. Remember the space shuttle has all the aerodynamics of a grand piano but its speed just about provides enough lift to land. It couldn't really fly around like an airplane. Then there are the earlier capsules that didn't even have 'wings' - they could (re)enter atmosphere once using ablative shielding, so presumably they were not "sreamlined"?

An "airframe" hull costs more but allows higher maneuverability in atmosphere.

 

[Starviking]

I also don't think CG will allow you to float down into an atmo from vacuum without any worry about wind shear and heating from friction. Basically even with CG (imo) it's still a hot entry into any atmo.

Turn on CG in orbit.

Cancel orbital velocity.

Float down 100-odd miles. 60 mph should see you down in just over an hour and a half.

If you keep an eye out for jet-stream winds I see no reason why landing a *balanced* unstreamlined vessel should be more difficult than pootling along the road at 60 mph in a lorry loaded with unaerodynamic bits-and-bobs.

 

[Eggtooth]

Gravity isn't the problem - wind is

60 mph wind can cause structural damage if the shape catches the wind. It is probably save for most ships - even dispersed, but antennas and such might be damaged.

http://www.unc.edu/~rowlett/units/scales/beaufort.html

The streamlining is to prevent wind damage, not to allow flight without contragrav.

 

[robject]

Based on this I see no reason why semi-streamlined could not operate in atmo.

Depends on the ruleset too, perhaps. CT certainly has fuzzy boundaries that evolved over time, and perhaps didn't represent its categories well enough.

So see if the rules you're using treats streamlining in a particular way, and go from there. In CT it's not unreasonable to allow partially streamlined ships to land -- thereby implcitly re-categorizing "streamlined" as "airframe" or aerodynamic or similar.

Other rules may lay it all out better.

 

[the angle]

With the tech available in Traveller, especially gravity manipulation, I assume that "streamlining" can be accomplished in ways that supercede making the hull aerodynamic. In other words, a "streamlined" hull may be as knobby and angular as you want if it has some sort of internal mechanism to wrap the hull in an aerodynamic envelope -- call it a "sonic fold generator" (a term that I stole from some SF story, damned if I can remember who came up with it). The additional construction price for streamlining can represent this capability as easily as some sort of airfoil shape -- plus that inserts something else into the story that can malfunction or be damaged at just the wrong time.

Steve

 

[Madarin Dude]

Streamlining effects the overall atmospheric speed so it is necessary to some extent. So I am in agreement with most of the above posters. Since there are no mechanics for sonic fold generators i will say it needs at least a bit of streamlining.

 

[Ran Targas]

What about ablative shields that could be inflated or mounted on the nose of a non-streamlined spacecraft? Not much different than the balyuts (sp?) on the Leonov in the film 2010.

In case of emergency or just to get the darn thing on the ground for a spell, an inflatable, ablative shield could be rigged, used to protect the ship during descent, then ejected when speeds were reduced to a point where streamlining didn't matter.

Might make for some interesting color the next time your players need to get repairs done on a backwater world.

 

[Madarin Dude]

What about ablative shields that could be inflated or mounted on the nose of a non-streamlined spacecraft? Not much different than the balyuts (sp?) on the Leonov in the film 2010.

In case of emergency or just to get the darn thing on the ground for a spell, an inflatable, ablative shield could be rigged, used to protect the ship during descent, then ejected when speeds were reduced to a point where streamlining didn't matter.

Might make for some interesting color the next time your players need to get repairs done on a backwater world.

Sounds like a cool emergency system for a non streamlined ship. If you need to land your Leviathan class please read the emergency instructions.

 

[Icosahedron]

60 mph wind can cause structural damage if the shape catches the wind. It is probably save for most ships - even dispersed, but antennas and such might be damaged.

http://www.unc.edu/~rowlett/units/scales/beaufort.html

The streamlining is to prevent wind damage, not to allow flight without contragrav.

I'm not sure that a dispersed structure would be safe in high winds, and we're talking several hundred mph winds up there...

...but heat is another problem. Part of the heat of reentry is due to speed friction which you can remove with a grav drive, but part of it is due to the naturally high temperatures of the upper atmosphere, and a slow drop won't affect that. I'm not sure of the figures, but if you're interested enough, check it out.

 

[robject]

I suspect that all atmospheres are dangerous places, once we're above a certain altitude, for various reasons. But... if your partially streamlined ship is adequate to skim hydrogen by diving into a gas giant's atmosphere, surely that's worth something...

 

[far-trader]

If your partially streamlined ship is adequate to skim hydrogen by diving into a gas giant's atmosphere, surely that's worth something...

Of course it is. It's good for skimming a gas giant upper atmosphere for fuel. A process that takes hours. So it's not a dive (hot plunge) into the heart of the atmosphere. It is a loitering just above the cloud tops skimming the very thinnest reaches of the atmosphere. Said thinnest reaches being enough to destroy an unstreamlined ship of course.

Essentially it comes down to this:

A ship has to be streamlined to enter an atmosphere and land on the surface of a planet. Period. (depending on rule set definition of "streamlined"). It's a game rule. That's all. A reason to have streamlined ships that cost more. Otherwise everyone will build the cheapest unstreamlined hull they can all the time. So it doesn't matter what anyone thinks CG is capable of doing (and it doesn't exist in CT). The rule is unstreamlined ships can't enter atmospheres to land on a planet. Period.

Now if you want to go the other way for your game that's cool. It IS your game. Just be ready when the players ask "Why aren't all ships unstreamlined?"

 

[rancke]

Now if you want to go the other way for your game that's cool. It IS your game. Just be ready when the players ask "Why aren't all ships unstreamlined?"

Because to a company, a ship that has, say, a 1 in 36 risk of coming to grief when entering an atmosphere is a really, really bad investment (Even worse if the risk is 1 in 36 when entering thin atmospheres, 3 in 36 when entering standard atmospheres and 6 in 36 when entering thick atmospheres). Whereas a Free Trader might be desperate enough to try it once in a while. Especially one crewed by PCs.


Hans

 

[far-trader]

That's what I meant Han's, have a house rule to cover it.

EDIT: Looks like I misread Hans' post above So my reply below is a bit goofy context wise...

But I question your risk aversion and assessment. What company or government in their right mind is going to routinely run a 1 in 36 risk of losing a multi-million cred or more ship? At the cost savings of a couple million cred? Not even a 1 in 360 risk sounds likely to pay off. No, if the ships are routinely going to land that means practically no risk. Maybe 1 in 3600 (as in unlikely in the ship's productive lifetime).

Unless you're talking just minimal damages when you say grief. But then again if the risk is so low nobody is going to waste good credits on streamlining hulls.

 

[rancke]

But I question your risk aversion and assessment. What company or government in their right mind is going to routinely run a 1 in 36 risk of losing a multi-million cred or more ship? At the cost savings of a couple million cred? Not even a 1 in 360 risk sounds likely to pay off. No, if the ships are routinely going to land that means practically no risk. Maybe 1 in 3600 (as in unlikely in the ship's productive lifetime).

That's what I was trying to say. Unstreamlined ships don't need to be completely unable to enter atmosphere for people to build streamlined ships. It doesn't have to be either/or. A modest risk is enough to make it unprofitable. To be honest, I think the "Streamlined ships can't enter atmosphere uner any circumstances, no how, no way" bit is the simplified game rule, not the accurate reflection of "reality".


Hans

 

[far-trader]

Ah, I think I misread your earlier. Now I get where you're coming from.

...To be honest, I think the "Unstreamlined ships can't enter atmosphere under any circumstances, no how, no way" bit is the simplified game rule, not the accurate reflection of "reality".

Totally agree there.