Airships, Huzzah

[tbeard1999]

I like airships. So in my campaign, they're everywhere. Here are some rough stats for dirigibles.

Typical TL10 dirigibles
Size: 7,000 dtons-90,000 dtons
Crew: 2+(dtons/20,000 rounded up).
Speed: 150 kph sustained
Duration: fusion powered; limited to consumables (28 days typical)
Cost: Cr300 per dton
Lift capacity in metric tons: size in dtons * AR
(AR=atmosphere rating .004 for thin; .006 for standard; .010 for dense).
Typical cruising altitude: 1000-3000m (3000m max normally)

Note: most gear will average 4 metric tons per dton. Dense machinery will average 14 metric tons per dton, but allowing for access space will bring this down somewhat.

Edit: Note that airship capacity is in metric tons, not dtons. Volume isn't a problem with airships; mass is.

These are the basic ratings for a dirigible with basic TL10 controls and avionics, powerplant, engine, a bridge and 1 stateroom for each 2 crewmen. Additional components can be added. The most common are staterooms (1 mt/Cr20,000 each) and weaponry (actual weight x 2 for mount). Increase the cost of staterooms by Cr5,000 if filtration gear is required. Starship components can be added; mass in metric tons is tonnage in dtons x 4.

TL Hindenburg sized Dirigible
Size: 27,000 dtons
Crew: 4
Base Cost: MCr8.1
Speed: 150 kph four weeks duration
Base Lift Capacity: 108 mt in thin; 162 mt in standard; 270 mt in dense.
100 staterooms; 62 metric tons cargo
Final Cost: MCr10.1

(By comparison, the TL5 Hindenburg would have required at least triple the crew and had a carrying capacity of about 50% of its TL10 counterpart).

The skin of a Dirigible is treated as Cloth.

EDIT: Modern (TL8+) dirigibles do not require ground crews, as their vectored thrust engines allow them to act like VTOL aircraft and hover under their own power.

 

[tbeard1999]

I should add that a helium filled airship will be a tough target to take down (assuming TL10 self-sealing gasbags and fireproof construction). The reason is that they are freakin' huge. In CT terms, an airship can't really be harmed by small arms and even large weapons won't do much damage to the ship (though they can cause a lot of harm if targeted at engine pods or control rooms).

 

[Icosahedron]

I'm a fan of airships, too. Not in a geeky airship-spotting sense, but they strike me as a logical form of transport in a fusion society that is pouring out quanties of helium as a by-product of power-generation.

 

[ShapeShifter]

Cracking good work, old man! Skyward, hooo!!!

 

[beowulf2044]

I am a fan in a geeky, airship-spotting sense. One of mankind's best acheivements, in my own opinion (and in its own time-reference).

 

[The Oz]

Note: most gear will average 4 metric tons per dton. Dense machinery will average 1 metric ton per dton, but allowing for access space will bring this down somewhat.

Most gear averages 4 tons per dton but dense machinery is less dense than that? What am I misunderstanding here?

 

[tbeard1999]

Most gear averages 4 tons per dton but dense machinery is less dense than that? What am I misunderstanding here?

<smacks palm on forehead>

Duh-oh. Dense machinery averages 14 metric tons per dton.

EDIT: Since a dton is about 14 cubic meters, this works out to 1 metric ton per cubic meter of volume (the default assumption in Striker and FFS).

But I looked at the volume of several modern tank engines. Modern diesels average about 0.6 metric tons per cubic meter and gas turbine engines average about .85 metric tons per cubic meter. So maybe the appropriate conversion should be about 10 metric tons per dton for dense machinery.

 

[tbeard1999]

I am a fan in a geeky, airship-spotting sense.

Yeah, me too.

One of mankind's best acheivements, in my own opinion (and in its own time-reference).

Certainly among the most beautiful, dramatic and memorable forms of transport ever developed.

 

[Whipsnade]

Gents,

I've always dirigibles, yet never really got as chance to use them in any game! The closest I got was when my players got shanghaied into investigating a dirigible cash on Winston.

When I saw that there were dirigible building rules in COACC I book the book immediately.

If anyone is interested, let me recommend Dr. Echener's Dream Machine by Douglas Botting. It primarily covers the round-the-world flight of the Graf Zeppelin but touches on many other related topics too. I especially loved reading that passengers' first request after landing were for baths. There was very little water for bathing aboard, you'd get little more than what you could use for what my father referred as a "PTA shower".


Regards,
Bill

 

[tbeard1999]

Gents,

I've always dirigibles, yet never really got as chance to use them in any game! The closest I got was when my players got shanghaied into investigating a dirigible cash on Winston.

When I saw that there were dirigible building rules in COACC I book the book immediately.

If anyone is interested, let me recommend Dr. Echener's Dream Machine by Douglas Botting. It primarily covers the round-the-world flight of the Graf Zeppelin but touches on many other related topics too. I especially loved reading that passengers' first request after landing were for baths. There was very little water for bathing aboard, you'd get little more than what you could use for what my father referred as a "PTA shower".


Regards,
Bill

That's kinda surprising, since dirigibles used water for ballast. But I guess the plumbing necessary to use that water for bathing would have been prohibitively heavy.

The striking thing to me is how little airships can actually lift (considering their size).

Of course, Traveller can enable zeppelins by (a) postulating further improvements in materials science and (b) providing worlds with dense atmospheres.

I'll get that book.

 

[Whipsnade]

That's kinda surprising, since dirigibles used water for ballast. But I guess the plumbing necessary to use that water for bathing would have been prohibitively heavy.

Ty,

The book has some nice excerpts of "life aboard" reports filed by one Lady Grace Hay-Drummond-Hay. (Not even I could make that name up!) Lady Hay was one of the brigade of 1930s fearless, globe trotting, "girl reporters". She worked for the Hearst organization and several London papers, they paid her way aboard the Graf on all the record making flights and she sent them columns when she could get radio time. She seems to have been a favorite of Dr. Echener's too.

She nicely describes time aboard the Graf as "a picnic life" and talks about "washing in a teacup". During the Graf's first Atlantic crossing the menu each day was eggs and coffee for breakfast, soup, meat, and stewed fruit for lunch, bread and sausage for dinner. Some kind soul had sent the passengers a luxury basket with the usual caviar, pears, and cognac and it was emptied the first day out. They ran out of bottled water during the crossing too. One of the stewards brought aboard a bit of tea for Lady Hay in his dunnage and he'd smuggle her a pot every afternoon at 4:30. She also seems to have been a favorite of the crew.

During each of the Graf's various historic trips, the crew and passengers would be feted wherever they landed. Lady Hay would describe the whirlwind of well wishers and remark how all she wanted was "a manicure, a bath, and some sleep".

It was a nice little book with a nice little story that ends in tragedy with the Hindenburg and the Nazis.

As you pointed out, advances in material sciences among many other things would give the Imperium's 57th Century dirigibles quite an edge over Dr. Echener's dream machines.


Regards,
Bill

 

[Icosahedron]

<smacks palm on forehead>

Duh-oh. Dense machinery averages 14 metric tons per dton.

EDIT: Since a dton is about 14 cubic meters, this works out to 1 metric ton per cubic meter of volume (the default assumption in Striker and FFS).

But I looked at the volume of several modern tank engines. Modern diesels average about 0.6 metric tons per cubic meter and gas turbine engines average about .85 metric tons per cubic meter. So maybe the appropriate conversion should be about 10 metric tons per dton for dense machinery.

At the risk of instigating more palm-smacking, those engines will float! Water is 1 metric ton per cubic metre. Unless you're including access space.

IIRC there was some discussion of this last year on the CT-Striker Yahoo Group. They concluded about 5mt per cu m (70mt per dT) was typical for machinery (excluding access space).

 

[RKFM]

The striking thing to me is how little airships can actually lift (considering their size).

Of course, Traveller can enable zeppelins by (a) postulating further improvements in materials science and (b) providing worlds with dense atmospheres.

I'll get that book.

I'm don't know much about airships, but I seem to remember some article or such that talks about actually shaping the bag into an airfoil shape to increase lift.

 

[aramis]

At the risk of instigating more palm-smacking, those engines will float! Water is 1 metric ton per cubic metre. Unless you're including access space.

IIRC there was some discussion of this last year on the CT-Striker Yahoo Group. They concluded about 5mt per cu m (70mt per dT) was typical for machinery (excluding access space).

Take the motor of my van. THe motor itself fits in a compartment 1.3m wide, 0.5m deep, and 1m tall. (about 0.75 m^3). Said motor weighs under a ton. A lot of the space in that compartment is taken up by access for occasional maintenance, and some is airflow.

Generally, the working space for a part correlates to about SG 2 for parts made from SG 6 to 9 materials.
The maintenance access for naval quality maintain-aboard is about twice that volume.

So the mass-ratios in striker include working space (SG < 0.01 for std atm.), and the part.

BTW, a jet engine, if you seal it up, WILL float. The Navy has occasionally lost a jet engine wrapped up for shipping, and if the wrap is water tight (which it is apparently supposed to be), it will float unless the water pressure causes a fitting to rupture the wrapping.

Heck, MOST vehicles, were they wrapped in a watertight wrap, will float.

The Apollo capsule: 5800 kg and 13.82 m³ (approximate). Or about 4.4Tmass per Tdisp
Apollo SM: 24500 kg and 90.31 m³ or about 3.8 Tmass per Tdisp

The Lunar Module's Ascent stage was only about 90kg/cubic meter or roughly 1.25 Tmass per Tdisp

 

[boomslang]

I should add that a helium filled airship will be a tough target to take down (assuming TL10 self-sealing gasbags and fireproof construction). The reason is that they are freakin' huge. In CT terms, an airship can't really be harmed by small arms and even large weapons won't do much damage to the ship (though they can cause a lot of harm if targeted at engine pods or control rooms).

Do not overlook the fact that fusion powerplants (starship or otherwise) produce helium as a waste product -- which is a fairly important potential source given how expensive mining (and recycling) naturally-occurring helium is otherwise.

And therefore enterprising regular Travellers to airship-favoring worlds might convert their some or all of their fuel tankage to store the captured exhaust from their drives for sale or swap.

Have you priced a cubic liter of helium lately? Historically, the costs of helium production have always risen...

:devil:

 

[atpollard]

The density of an entire airship is almost exactly the same as air (for obvious reasons).

That's 16.8 kg per dTon (1.2 kg/cu.m.).

 

[tbeard1999]

At the risk of instigating more palm-smacking, those engines will float! Water is 1 metric ton per cubic metre. Unless you're including access space.

IIRC there was some discussion of this last year on the CT-Striker Yahoo Group. They concluded about 5mt per cu m (70mt per dT) was typical for machinery (excluding access space).

Well, maybe so, as suprising as that seems. The engines in question included the M1 Abrams' AGT-1500 gas turbine engine (1.302 cubic meters; 1.134 metric tons). http://www51.honeywell.com/aero/com...SurfaceSystems/AGT1500_Turbine_Technology.pdf

But note that the volume is calculated from the dimensions, so there's definitely some air space there.

The diesel engines on the Leopard 2 series were heavier, but significantly less dense (didn't keep the links) than the AGT-1500. They are also much more "squarish" so there is less air space there.