Again odd wanderings with Cargo craft..
- Thread starter infojunky
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That seemed a bit too high, so I did a quick check on Google:
"How many cubic meters is a Boeing 747?
At 31,285 cubic feet (876 cubic meters), the 747-400 has the largest passenger interior volume of any commercial airliner, which is equivalent to more than three houses each measuring 1,500 square feet (135 square meters)."
That converts to about 65 dTons.
"How many cubic meters is a Boeing 747?
At 31,285 cubic feet (876 cubic meters), the 747-400 has the largest passenger interior volume of any commercial airliner, which is equivalent to more than three houses each measuring 1,500 square feet (135 square meters)."
That converts to about 65 dTons.
That is just the cargo volume. Note the various A classes 200 dTon traders are in the 40 to 80 dTon range for Cargo.
I thumbnailed off of the fusalage measurements which ballparks into the 200 dTons.
Condottiere
SOC-14 5K
Streamlined, needle, aerofins.
If it helps I was using the stats from the 747-800F.
But honestly I was pondering types of cargos such small ships would focus on. Thus the looking at Air Freight instead of Ship Freight.
Spinward Flow
SOC-14 5K
This is honestly the better approach to take when it comes to interstellar transport.
It isn't called aerospace for a trivial reason.
The value of air cargo on Planet Dirt is simply their speed and ability to fly inland. Surface travel is chosen for cost value where time is not as important as cost.
Of course, none of these are an issue with space/starships. They can all go wherever they want, as fast as they want. It's a real question whether surface vessels have any real value save perhaps for some very specialty things. I don't know how much cheaper a 200 ton surface freighter would be vs a space ship (i.e. no jump drive) for domestic cargo.
Of course, none of these are an issue with space/starships. They can all go wherever they want, as fast as they want. It's a real question whether surface vessels have any real value save perhaps for some very specialty things. I don't know how much cheaper a 200 ton surface freighter would be vs a space ship (i.e. no jump drive) for domestic cargo.
One obvious consideration is the TL of the planet - if it's below 8, they won't have a native spaceship industry.
Comparing the cost of spaceships in Traveller, they come out to 10-20 times the price of current surface ships (assuming Cr1 is equivalent to £/$1; I seem to recall that in T5 Cr4 per hour is given for unskilled manual labour which would put the price differential 2.5 times more.
Another factor would be crew requirements - the average size of bulk carriers is about 9500 dTon, container ships about 11500, tankers about 7500. Typical crew size would be 4 deck officers, 4 deck ratings, 3-4 engineering officers, 4-5 engineering ratings, a cook and a steward's assistant. Tankers may have a few more deck ratings for fire/spillage duties; the "mega-ships" wouldn't have many more crew aboard. Depending on which version of Traveller is being used, the equivalent crews would be significantly higher for the same size of spaceship.
No, it's not.
The then-new USAF and its backers put a lot of effort to ensure that particular word gained general usage -- a terrific advantage in the mid-century inter-service rivalries.
Rockets are very-long-range artillery (Army). Having personnel in climate-controlled pressurized craft is very like submarine ops (Navy). But when you think in terms of "aerospace," it can't be anything but USAF... hence USAF Space Command (now the somewhat clichéd Space Force).
In the '50s, cruise missiles were designated as unmanned bombers as part of this effort (otherwise, they might be artillery and we couldn't have that!)
Krikkitone
SOC-12
Advantages of a Surface cargo ship v. Space cargo ship…. partly depends on planet environment.
surface ships don’t need
-artificial gravity (if world size 1+)
-extensive Life support (if atm is 2-9)
-same level of thrust (if Hyd 1+ or Airframe in atm 1+)
-armor against orbital speed space junk (if atm 1+)
All of that could lead to cheaper but slower shipments on the surface… even if dealing with grav vehicles. Now that will be most important for settlements far from the starport(s) to connect them..or on high pop worlds where a lot of goods are produced in one part of the world and consumed somewhere else on the world.
Also, depending on the atmosphere, waterborne ships can be wind-powered. This is useful on worlds whose petrochemical geological deposits either never formed, or were already exploited by a prior civilization. If you they don't have the TL for gravitics, and atomics and/or fusion, wind power looks pretty good. Batteries at that TL aren't particularly good...
Straybow
SOC-14 1K
No, the 876 m³ is correct for the passenger decks. Cargo is 159 m³. Add about 30 m³ of fuel for a usable volume of 1065 m³, excluding the ends of the wings, the tail and stabilizers. Actually, not sure if the 876 m³ includes cockpit and crew area, which has a little nap compartment in the nose. Anyway, 76 Td would be the Traveller size.
By comparison, the smallest 737 is 102 ft long, elliptical section ~14'×12', with a long tapering tail, comes to ~10500 ft³ = 21 Td.
This is one of the reasons I contend the 14 m³ "hydrogen displacement ton" was added after the 77 printing. Somebody noticed that water displacement tons wouldn't work for H2, and they could either use ship tonnage and ignore the difference or convert to hydrogen tonnage. I would do the former.
Using British Register Tons, the 20 ton launch would be the size of a small 29' city bus. 30 ton boat would be a long 45' city bus. 40 ton pinnace would be a 60' bendy-bus. 100 tons would be like a Coast Guard patrol ship (the 98-105 ton Cape class was in service in the '70s), or the short 737.
Condottiere
SOC-14 5K
My method starts with a scale model of a 747 with a known volume (in this case the model of a 747–8I here, which conveniently is solid and has a listed mass of material used).
The model is a 1:200 scale model made of PLA with a mass of 161 grams.
PLA has a density of 1.25 g/cm^3, so the model has a volume of 128.8 cm^3.
A 1:200 scale model has 1 cm^3 for every 8 m^3 in the original article (because 200^3 is 8 million and 1 m^3 is 1 million cm^3).
128.8*8 = 1030.4
The total volume is therefore approximately 1030 m^3, although it could be a bit bigger or smaller. I would leave it at “between 1000 and 1050 m^3” to account for modelling inaccuracies and the volume of the stand.
The model is a 1:200 scale model made of PLA with a mass of 161 grams.
PLA has a density of 1.25 g/cm^3, so the model has a volume of 128.8 cm^3.
A 1:200 scale model has 1 cm^3 for every 8 m^3 in the original article (because 200^3 is 8 million and 1 m^3 is 1 million cm^3).
128.8*8 = 1030.4
The total volume is therefore approximately 1030 m^3, although it could be a bit bigger or smaller. I would leave it at “between 1000 and 1050 m^3” to account for modelling inaccuracies and the volume of the stand.
Trying to find accurate volume details for the 747 isn't going to be easy. I've found one site that does give some figures for one of the -200 series and that gave me a cylinder volume for the fuselage of about 170 dTons. Adding on some volume for the wings, engines and the bulbous fore would bring it up to about 200 dTons.
I don't think they could have been using British/Gross Register Tons (1 GRT = 100 cu ft) as that would make the staterooms incredibly cramped, especially as that volume would also have to include some common space, eg corridors. Given that 1 GRT is about 2.8m^3, the volume would be about 1/5 of that from using the volume of 1000kg of liquid hydrogen.
I suspect they had the H2(l) volume in mind in 1977, but forgot to define it in the rules; I very much doubt they had the volume of 1000kg of water as the definition of the tonnage volume in mind as that would have made staterooms really tiny.
OK, a slight problem with that as the print isn't solid PLA; it's likely to have two (possibly three) solid outer walls, each 0.4mm thick, but the interior isn't solid - it's likely to be around 10-20% density. That would make the actual volume of the print quite a bit larger.
This is how I made my supposition.
Note historically some Traveller Illuminati placed the Space Shuttle at 95 dTons...
When you look at photos of the Space shuttle being carried on top of a 747, it being 95 dTons and the 747 being 200-250 dTons sounds about right.
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