Form follows function.

Discuss the Traveller RPG and its many settings
AnotherDilbert
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Re: Form follows function.

Postby AnotherDilbert » Thu Nov 01, 2018 12:06 pm

Old School wrote: Ya’ll just need to stop.
Very well.

This is certainly the wrong thread and the wrong forum for this discussion.

Sigtrygg, contact me privately, or on CotI, if you want to continue this discussion?
Sigtrygg
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Re: Form follows function.

Postby Sigtrygg » Thu Nov 01, 2018 5:42 pm

Yup, the fuel use rate is woefully inadequate for it to be a fusion rocket that functions as a rocket. The rocket equation is a harsh mistress.

MTU explanation was/is the m-drive uses gravitic technology to lower the inertial mass of the ship - since inertial mass and gravitational mass are at the moment proving to be the same thing. If grav modules can reduce gravitic mass for the purposes of being attracted to a planet then they should also reduce inertial mass. Since this is a field around the ship it explains why it is volume based. The inertial mass is reduced to such an extent that a plasma drive, ion engine or 'fusion' advancement of the plasma drive can accelerate the ship up to 6g (now 9g). You can't push it a higher acceleration because the field will collapse.

Strangely enough nuclear damper technology would make this more efficient at TL12+ since you can enhance the fusion reaction and decrease the harmful effects of the fusion exhaust. :)

If the gravitic bit of the m-drive is damaged then acceleration is reduced, lose all your gravitics and your engine thrust will be reduced to micro-g values or worse.
Sigtrygg
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Re: Form follows function.

Postby Sigtrygg » Thu Nov 01, 2018 5:49 pm

AnotherDilbert wrote:
Thu Nov 01, 2018 12:06 pm
Old School wrote: Ya’ll just need to stop.
Very well.

This is certainly the wrong thread and the wrong forum for this discussion.

Sigtrygg, contact me privately, or on CotI, if you want to continue this discussion?
True, we should be sticking to the MgT (and T5) descriptions of the m-drive.

I do enjoy the discussions though.

I would actually welcome a MgT version of the Starship Operator's Manual.
Condottiere
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Re: Form follows function.

Postby Condottiere » Sat Nov 03, 2018 12:41 pm

At the usual combat ranges, I rather doubt the backwash of the drives will damage other ships.

On the other hand, a smallcraft probing too close to the rear should get fried.
steve98052
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Re: Form follows function.

Postby steve98052 » Sun Nov 04, 2018 7:02 pm

After much thought on this topic, I have pretty much concluded that the cost in volume of the airfoil surfaces needed to generate meaningful aerodynamic lift would exceed the volume required to just bump up the maneuver drive to the point that it can take off and soft-land without aerodynamic lift. Want to land on a world with 1.5 G of surface gravity? Install a Maneuver-2 drive (or a Maneuver-1.6 drive if rules allow). Want to refuel at a gas giant with 2.53 G gravity (Jupiter) at an altitude where the atmosphere is dense enough for the intakes? Install a Maneuver-3 (or 2.6 in allowed) drive.

There would be exceptions. An obvious example is an aerospace plane (defined as a vehicle that flies in both atmosphere and space, using significant aerodynamic lift while in atmosphere) built on worlds that don't have gravitic drives. A few real-world examples are under development, and the Space Shuttle was such a vehicle when returning from orbit. Such vehicles would be most efficient if designed for a specific world; gravity, atmospheric density, and atmospheric composition (oxidizing, reducing, non-reactive).

The constraints of aerodynamic lift make it impractical for starships, except possibly in cases where the starship is designed for a specific route between two very similar worlds.

That doesn't mean streamlining and aerodynamic control surfaces are useless. Streamlining allows a faster trip through an atmosphere, and control surfaces make a vehicle more maneuverable in atmosphere, even if the maneuver drive is powerful enough that lift is unnecessary.

Does anyone see any fault in that conclusion?
Sigtrygg
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Re: Form follows function.

Postby Sigtrygg » Sun Nov 04, 2018 7:15 pm

You don't use mechanical control surfaces.

Traveller ships have a plasma around them, you manipulate this to produce the aerodynamics you want.

Before you ask CT adventure Beltstike - the maneuver drive produces a field around a ship to deflect radiation, this must be a plasma filled field to work the way described.
Condottiere
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Re: Form follows function.

Postby Condottiere » Mon Nov 05, 2018 5:13 am

Grav/lifters allows a tightly controlled descent.

You can always place ablative armour at critical spots on the hull, like the nose.
AnotherDilbert
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Re: Form follows function.

Postby AnotherDilbert » Mon Nov 05, 2018 5:16 am

Sigtrygg wrote: Before you ask CT adventure Beltstike - the maneuver drive produces a field around a ship to deflect radiation, this must be a plasma filled field to work the way described.

I fail to see that Beltstrike implies anything much about how it works:
CT Beltstrike, p2 wrote:Ships under power are not affected—part of the M-drive generates a low-power screen against radiation and meteorite impact ...

A thin plasma would provide next to no protection against hard radiation and micrometeorites.
Sigtrygg
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Re: Form follows function.

Postby Sigtrygg » Mon Nov 05, 2018 6:20 pm

I beg to differ, there's a surprise.

I have read many article over the years about real world propositions to use plasma fields and magnetic fields to shield spacecraft from particulate radiation and micro-meteorites.
steve98052
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Re: Form follows function.

Postby steve98052 » Mon Nov 05, 2018 6:50 pm

Maybe a plasma shell would work as a shield against some space radiation and micrometeoroids. I haven't seen the same articles.

But I don't think that would work as a substitute for aerodynamic surfaces during atmospheric flight.

It's reasonable to argue that movable aerodynamic control surfaces might not be ideal for a gravitic vehicle in atmosphere. But fixed stabilizers, in combination with vectored gravitic "thrust", would make atmospheric flight smoother.

A plasma shell in atmospheric flight seems like something that planetary authorities would frown on. In the lower reaches of an.Earth-like atmosphere, a plasma shell would generate a lot of nitrogen oxides, which are a pretty noxious pollutant, creating smog and acid rain. In the upper atmosphere, a plasma shell might also be a problem; nitrogen oxides are hard on the ozone layer.

Real-world re-entry vehicles, including ablative heat shields like the Apollo capsules and non-ablative surfaces like the Space Shuttle tiles, generate their own plasma layer during the hottest part of re-entry. If space flight were routine, that would be a pollution issue. Intentional plasma layers would be a problem.

I would also think that it would be a rough ride, along the lines of a super-cavitating submarine. But inertial compensation might mitigate that.
phavoc
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Re: Form follows function.

Postby phavoc » Mon Nov 05, 2018 8:13 pm

Wouldn't the plasma shell also render communications useless? It has for Apollo and the Shuttle. Or at least radio would be that way. I suppose one could TRY to get a laser whisker out, but it'd probably be damned near impossible. And meson communications should be fine.
Linwood
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Re: Form follows function.

Postby Linwood » Wed Nov 07, 2018 1:17 am

I have vague memories of a brief article in NASA Tech Briefs about experiments in generating plasma on the outer surface of an airfoil as a control surface. No idea if the technology worked....

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