Cray
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Posts: 4147
Loc: North America
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Ground Launched Jumpships
#54650 - 03/13/03 05:00 AM (147.160.125.185)
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The NAIS "Advanced Core Jumpship Project" (ACJP) strove to make two unrelated but very complementary breakthroughs in jumpship technology.
The first was less a breakthrough than a re-application of an old jumpship design feature, one that was abandoned with the advent of the first true dropships in the late 2400s/early 2500s. With the advent of true dropships, jumpships were pared back to the bare minimum: tiny, stationkeeping drives, a crew section, and a KF drive. This design minimized the mass that had to be encompassed by the drive's hyperspace field, and (safely) encompassing more mass was very expensive: witness the price of a docking hardpoint for a dropship, or the expense of a warship's KF drive. A couple thousand extra tons of equipment amounted to another dropship the drive had to carry - little wonder jumpship designers pared down the ships to the bare minimum once dropships became common. However, the jumpship designers of the ACJP held to the theory that the old ship architects had gone too far by making a jumpship's non-drive mass equal to 1/19th of the drive's mass (i.e., the drive was 95% of the ship's mass). With a drive that was 90% of the ship's mass, some fascinating possibilities for ship design were opened. To avoid scaring away customers, this "innovation" was dubbed "the high capacity civilian KF drive" rather than "the advanced civilian KF drive." Of course, the high capacity drive was twice as expensive as the standard KF drive....
The second breakthrough was a true breakthrough: a replacement for the rare and expensive germanium in KF drive cores. The ACJP tested new superconductors for the KF drive core. While this resulted in some spectacular (mid-jump) failures, particularly from the more chemically complicated ceramic superconductors, the simple magnesium diboride superconductor was readily adopted for KF drive use. With a critical temperature of 38K, it could be cooled (with a significant safety margin) by liquid hydrogen (20K) rather than the more expensive and obnoxious liquid helium that germanium needed. This development resulted in 7 attempts to sabotage the ACJP design facilities (5 of which have been traced back to germanium mining firms) and a crash in Inner Sphere germanium prices. The prices mostly recovered once everyone remembered the Inner Sphere's jumpship production capacity is so low that it'll be a couple of centuries before MgB2 can replace Ge in KF drive cores.
The ACJP moved beyond technology development and made a solid effort to transfer its innovations into the jumpship industry. Several jumpship firms have licensed the MgB2 technology while several of the ACJP's leading engineers went into private industry to start their own jumpship firm. It was a great deal easier than it sounds, mostly because of the first "innovation."
A JOINT VENTURE AND THE RESURRECTION OF A GIANT
The ACJP engineers teamed with a small, local aerospace firm (Raven Aerospace) that built a couple hundred jumbo airliners and a couple dozen shuttles annually and a shipyard (Neptune Marine Technologies) that turned out multi-hundred kiloton freighters and LNG tankers for local oceanic trade. A major subcontractor was LTV Fusion Engines, which produced several grades of small fusion engines (like the common 160 LTV and the huge 400 LTV) and titanic civil power plants. The joint venture was known as Pioneer Interstellar.
Raven Aerospace (RAS) was not hired to supply any jumpship-related technology. Rather, it supplied the knowhow for "basic" aerospace systems like pressure hulls, life support, power systems, etc. Neptune Marine Technologies (NMT) would do the grunt work of assembling the planned jumpship (and dropship) hulls and large fusion engines. It had the experience not just with large, mobile structures, but also with moving large structures under gravity. Its 500000-ton tankers were typically assembled in "modules" and moved (by barge and overland) several kilometers to a common assembly slip where cranes moved the multi-thousand-ton "modules" into place.
The reasoning behind this alliance came from the size reductions in jumpships a "high capacity" drive made possible. The example seized on by Pioneer Interstellar was the ability to copy the Invader-class jumpship's capabilities at half the tonnage, or 75000 tons. This tonnage was important because of a historical footnote: the Colossus-class dropships. Though the Colossus-class dropships had died with the Star League, they were not forgotten in aerospace text books. The 100000-ton Colossus had ferried ground-built components up to warship shipyards during the Star League, including components (often whole fusion engines) as large as 80000 tons. RAS's, NMT's, and LTV's experience would enable such titans to live again, and give them a new use:
Launching ground built jumpships into orbit.
The Colossus II only had its name and general role (cargo delivery) in common with its Star League-era predecessor. It was powered by new engines from LTV, five beasts each heavier than a fully laden Union-class dropship (or swallow). These engines had been developed by LTVs as demonstrators for several warship engine contracts it had unsuccessfully pursued. (And they were the reason LTV was selected over fusion engine companies that offered lower bids.) The Colossus was little more than a 300-meter tall, 200-meter diameter hollow shelled egg. Its lower 25 meters were stuffed with the epic-scaled fusion engines and engineering spaces, plus ballast tanks. The ballast tanks enabled the Colossus to settle in water until its cargo deck was submerged so a jumpship could simply be floated into the bay. Water landings made life easier for nearby spaceports, which were incapable of handling the dropship. It also simplified the design of the landing gear by reducing it to fixed pads like the Mammoth's landing "gear," but moreso: the Colossus II would only need its landing gear on low gravity moons and asteroids. At the very top of the Colossus II was the docking hard point, crew quarters, and bridge (easily built separately and docked into place). The entire section could be ejected like a 1000-ton escape pod. In between was little but open space and bracing to hold tall, needle-thin objects (jumpships) in place during launch.
The Colossus II was technically rated to put 75000-ton jumpships into orbit, but there was some fudge room in that. First, the Colossus II could lighten itself by launching with partial fuel tanks - it only needed a few tons of fuel to get into orbit even when fully laden. Second, the jumpship could do the same, and certainly didn't need its cargo bays full at launch. These two weightsaving efforts would enable jumpships somewhat over 75000 tons, perhaps 80000 tons, to be launched. Third...well, the Colossus II's engines were rated to supply 150,000 tons of thrust without straining, or 250000 tons at full overthrust. With the fuel efficiency of fusion engines, the Colossus II only needed a small margin of acceleration over local gravity to get into orbit. In theory, the Colossus could put 175000 tons of cargo into orbit with thrust to spare. However, its designers and crews were rather wary of running the high-power, high-strung fusion engines at full overthrust.
Engineering the Colossus II was not without troubles, but the hard part (the engines) were already available. The rest involved adapting the facilities (and workers) of a shipyard meant to build oceanic ships into a shipyard that could also build spacecraft.
BIRTH OF THE PIONEER-CLASS JUMPSHIP
The Pioneer was the ultimate proof of principle for the ACJP. It was a 75000-ton jumpship with 3 docking hardpoints meant to be built in the benign, familiar environment of a planet's surface.
The effort was not without its challenges, most of them involving casting the 66000-ton, 161-meter long, 14-meter diameter bar of magnesium diboride core to the correct specifications. This took several (expensive) trials and very expensive, unique continuous casting equipment and a huge heat treating furnace to relieve casting stresses. Once this process was proven to work in gravity (the ACJP had used normal zero-G casting facilities at existing shipyards to create the first MgB2 cores), the project advanced to building the rest of the jumpship.
In normal production, the crew module for the front of the Pioneer, the engine module for the rear, and cylindrical mid-body sections were assembled at various points around the shipyard, all simultaneously. At final assembly, the midbody sections would be joined together into a 150-meter long cylinder (rather like assembling a small submersible cargo ship), the core would be slid into its hydrogen cryostat, then the cryostat loaded into the midbody (often accompanied by obscene comments from shipyard workers), and the engine and crew modules welded onto the ends. Aside from the drive core, most of the ship's "modules" were considerably lighter than the aquatic ship "modules" NMT was used to working with. The ship was slid sideways into the water like a small ship or submarine, then nudged by tugs toward a waiting Colossus II.
Loading the Pioneer into the Colossus II involved some impressive crane, winch, and ballast work, because the fragile jumpship's structure was only able to endure launch stresses on its tail. Once in position and braced with cargo bay arms and trusses within the Colossus II, the dropship would be moved up the coast to a special, artificial launch bay far from civilization (to avoid noise pollution lawsuits and fines for endangering local whale populations). Then, of course, it would launch.
Not counting the government-funded ACJP, the process of designing and building the Pioneer (and Colossus II) cost over 15 billion C-bills. As large as that number is, this was "only" a medium-high risk investment for RAS and NMT. Both would probably have survived if the Pioneer failed (which it did not). RAS and NMT were small compared to interstellar megacorporations like Federated Boeing and Ceres Metals, but they were larger than many early 21st Century "mega" corporations on Terra. They both had large shares of local aerospace and shipbuilding markets (respectively) on a planet with a population of billions. 15 billion C-bills amounted to ~$45 billion (US $ 2003), a survivable investment.
PIONEER-CLASS JUMPSHIPS: CAPABILITIES
The Pioneer did not fail. It delivered the capabilities of an Invader at half the mass. By being constructed on a planet's surface, it avoided the need for the highly specialized (and expensive) training and support of zero-G workers, and avoided a lot of very expensive zero-G facilities. Though the first 4 Pioneers were built with germanium cores (to test one technology at a time) and the germanium option remained available, all later Pioneers were built with MgB2 cores, further reducing the price. Not only did the Pioneer deliver the capabilities of the Invader at half the mass, it did so at half the price.
Or could do so at half the price. Pioneer Interstellar initially charged 400 million C-bills per Pioneer rather than 250 million to recoup the initial investment.
Aside from its size and drive, the Pioneer is a fairly typical jumpship. It has 3 docking hard points (in the unusual arrangement of 2 on the long, slender midbody and 1 on the bow of the ship). Its spherical crew section has a whole deck dedicated to small craft, with a door each on the dorsal, starboard, ventral, and port sides of the crew section. Because most Pioneer owners operate in House core worlds, the bays typically hold 4 shuttles rather than any fighters.
Above the (toward the bow) fighter bay doors is the 100-meter torus holding the two counter-rotating gravdecks. With their small diameter, they are best suited for simulating about 0.2G (lunar gravity), and even then visitors tend to be disturbed by the fast (2rpm) spin. Crew quarters are available on the gravdecks (which are basically 314-meter long hallways - plenty of room for the whole crew) and in the bulk of the crew section. The gravdecks also hold spaces intended for hydroponics, but RAS's life support division has had trouble making the hydroponics work as a fully enclosed life support system. Currently, the hydroponics just provide some fresh vegetables and fruits to the crew, or are emptied and left unused. The Pioneer has very comfortable and roomy crew quarters. As with other BT spacecraft, the Pioneer has a lot of volume for its tonnage - providing extra elbow room is easy. The bow has a docking hard point for a third dropship. Slightly behind this is the ring of ports providing "forward" views to the crew on the toroidal bridge.
The Pioneer's stationkeeping drive is a cluster of five, small (180-ton) engines. Because stationkeeping thrust needed at zenith and nadir points is so miniscule (far below the 0.1G stationkeeping drives can manage), only three of the engines are kept powered up, and only 1 is actually supplying thrust. As with the crew section, the engineering section has abundant elbowroom. The stationkeeping drives can be individually deactivated and pulled inside for maintenance in a pressurized, shirtsleeve environment, and most other systems are dwarfed by the roomy access halls around them. The Pioneers with MgB2 cores have some additional pumps that cross-link their fuel tanks with the core's hydrogen bath, given the Pioneers additional safety in the case of an emergency, like a coolant leak.
The two midbody docks reveal one of the limitations of small jumpships: the Pioneer can actually seem dwarfed by the attached dropships. Even with dropships that have smaller diameters than the Pioneers 200-meter length (like 100-meter diameter Overlords) can seem to dwarf the needle-thin (20m) jumpship with their bulbous forms. Mammoths and Behemoths are even worse. Should Pioneer Interstellar build its Pioneer-B (see below), it will have an actual problem fitting dropships around the narrow core of the Pioneer.
For defense, the Pioneer has an array of relatively low tech weapons. Twelve PPCs should discourage the light aerospace forces most pirates possess while twelve small pulse lasers function as multi-role anti-debris, anti-boarder, and anti-missile point defense systems. To keep things simple, the Pioneer was fitted with standard oriented graphite radiators using ammonia coolant (single strength heat sinks). Armor is standard steel/DFR boron nitride and quite thin. (Actually, I didn't know how much armor a jumpship could carry and guessed. Remove cargo capacity to beef it up to max, or add to cargo capacity if excessive).
Finally, the Pioneer has an oversized sail and bridge. The sail was hedging on the part of the shipyard designers who thought that it was fairly harmless to increase the size on the "solar APU" to speed charging at dim stars. (They were used to thinking of auxiliary power units as 100-ton gas turbines or 200-ton marine diesels. Getting several extra megawatts for a few tons was great.) The oversized bridge is a leftover from the prototype testing period when extra crew were carried to monitor the MgB2 cores. Now the bridge has additional crew space and room for additional systems and upgrades.
The Pioneer was not without teething problems, but most were cleared up easily due to the modular design of the components and large amounts of equipment access space. First of the problems were saltwater corrosion, which the RAS designers had not allowed for. (They generally didn't build airplanes "in saltwater bathtubs", hence the lack of anticipation of corrosion from an aerospacecraft built in an oceanic shipyard.) Second, the bearings of the gravdecks did not handle operation during significant (0.1G) maneuvering as they were supposed to, which required lengthy and expensive gravdeck redesign and replacement. Third, there is an ongoing problem with the fabled "closed ecological life support system," which was supposed to provide completely recycled air, water, and food to the crew. Pioneers currently use standard mechanical systems to recycle air and water with some losses, and rely on stored food (which is part of the cargo mass, as are spare parts). RAS has gotten as far as a "mostly closed" recycling system, which should reduce food/water/air store needs by 90%-95%.
VARIANTS
Pioneer Interstellar has been considering a slightly enlarged Pioneer (Pioneer-B) that would mount 4 docking hard points. However, the compact form of the Pioneer is ill-suited to carry 4 hard points. Finding a workable configuration for docking 4 dropships is the primary obstable to introducing the 80000-ton Pioneer-B.
Pioneers are available with lithium-fusion batteries. These cost some of fuel, cargo, and smallcraft capacities (200 tons, 300 tons, and 1 bay, respectively). And they triple the price of the ship, of course.
RULES
The magnesium diboride (MgB2) cores halve the cost of a KF drive. They are not yet available for compact (warship) KF drives, but are available for standard and "high capacity" KF drives.
The "high capacity" KF drive is twice as expensive as standard KF drives. However, it only uses 90% of the vessel's mass rather than 95%. High capacity drives can carry 1 dropship per 20000 tons.
Ground construction of jumpships cuts the cost of a jumpship in half, possibly more as the shipyard(s) involved become more experienced. However, construction of jumpships on planetary surfaces imposes a distinct problem: the size of the available dropships to launch the jumpship. The current limit is about 75000 tons and 200 meters in length for the Colossus II dropship. (Remember: the Behemoth cannot land.) Warships cannot yet be built on the ground, though they usually have adequate thrust to launch themselves.
AND, FINALLY, THE SHIP
AeroTech 2 Vessel Technical Readout
NOT AT ALL VALIDATED
PIONEER CLASS
Tech: Inner Sphere / 3067
Vessel Type: JumpShip
Rules: Level 3
Mass: 75000 tons
Stationkeeping Drive: 900t
....Safe Thrust: .2 (0.1G)
....Maximum Thrust: .3 (0.15G)
KF Drive ("High Capacity"): 67500t
Jump Sail: 50t
Structural Integrity (SI 1): 500t
Total Heat Sinks (150 SHS): 63t
Fuel & Pumps: 510t
Bridge: 196t
Armor (Standard): 30t (?)
Cargo:
....Bay 1 (4 Small Craft with 4 doors): 800t
....Bay 2 (Cargo with 2 doors): 1145t
Armament:
....12 PPC (2/arc)
....12 Pulse Small Lasers (2/arc)
DropShip Capacity (3): 3000t
Grav Decks: (2x100-meter diameter): 100t
Passengers & Crew (40): 40t
Life Boats (10): 70t
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Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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Karagin
General
Reged: 04/21/01
Posts: 6412
Loc: Ft. Hood TX (Killeen)
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Re: Ground Launched Jumpships
[Re: Cray]
#142453 - 12/27/06 09:11 AM (70.123.166.36)
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Okay what gave you the idea for this one?
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Karagin
Given time and plenty of paper, a philosopher can prove anything.
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Karagin
General
Reged: 04/21/01
Posts: 6412
Loc: Ft. Hood TX (Killeen)
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Re: Ground Launched Jumpships
[Re: Karagin]
#156366 - 09/08/09 03:56 PM (72.178.75.99)
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This sounds like some of the ideas I have had...kind of like the Star Wars ships or some of the other sci-fi universe small freighters and such. This is one area that BT is different from the rest of the Scifi universe is the lack of freighters in the sense of small craft that can double as their own carriers via FTL travel.
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Karagin
Given time and plenty of paper, a philosopher can prove anything.
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His_Most_Royal_Highass_Donkey
Captain
Reged: 06/18/08
Posts: 917
Loc: Somewhere on the US highways
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Re: Ground Launched Jumpships
[Re: Karagin]
#166634 - 02/27/13 06:35 PM (108.103.121.24)
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This is a very interesting idea.
On my world I have no ability to build jump/drop ships do to having basically no zero-G shipyards beyond some minor small space-stations that EVAs are performed out of for dropship repair and refueling. The largest space-station in orbit is a union dropship that was so smashed up in battle its more a dead hulk than a ship. I had chemical thruster installed so it will stay in orbit and a fusion reactor from a battlemech to power its systems. Its original thrusters where striped out for the metal that they contained since that was all that they where good for do to damage.
If I could build planet side I might just start a dropship construction company. Nothing would boost my economy like building very rare things like dropships. My problem is being basically a bandit king I don't have access to enough highly educated and experienced zero-G construction crews. I just have enough to keep my fleet of Mule dropships and Merchant jumpships operating building dropships in orbit is out of the question.
How do I get my hands on one of thees Colossus IIs and how much do they cost? I am sure I can recoup the cost of buying a Colossus II with building dropships planet side and just doing final installing of components in orbit.
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Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
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Cray
General
Reged: 07/27/01
Posts: 4147
Loc: North America
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Quote:
How do I get my hands on one of thees Colossus IIs and how much do they cost?
Find a cooperative GM who allows fanfic custom DropShips in their game. A 100,000-ton, 3/5 DropShip with the required 75,000 tons of cargo space is about 750 million CB, according to a quick sketch in HMA.
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Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
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Col_Green
Private
Reged: 01/23/13
Posts: 33
Loc: Texas
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Re: Ground Launched Jumpships
[Re: Cray]
#166678 - 03/04/13 04:01 PM (99.9.128.106)
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I see one problem with this...sorry not trying to be a pain....but to me there is a reason why every corp or merc unit out there can't build DS planet side......it's because EVERYONE would then be building them.
Dont' get me wrong my unit also has the capital and people to start a bussiness like this...hell I wouldn't even have to run contracts anymoe I could just be garrison on in the Pirphery and my unit as the defense force.
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