The Savage Chicken
I decided I really should finish this before winter break, so here's the final set of quotes from Mark. There's about ten pages of miscellany, too, but people would get lost in that no matter how much I organized it. As noted in other threads, everything not in italics is from Mark.
It will be some time before the ship gets sold. I just wanted the ship to have some more motivations in life other than killing Sam. Now its got a goal to work for, and enough free will to take its own actions in reaching that goal.
The SC is a general purpose ship. Used for atmospheric work as well as orbital (and when the second fusion reactor gets repaired) and light in system work. The ejection seats are for work in the atmospheric stage, and are disabled when atmospheric pressure drops too low.
Being one of the initial ships in system, it was designed to be fairly robust, and operate even if all the systems weren't up. When a planet is being terraformed and initial industry still isn't in place, sometimes you just have to work with what you've got. As a system gets more civilized, the rules get tighter.
I've done what I can to make the ship look primitive and workable. Big flat plates instead of the smoothed curved plates that high tech finished products have. Valves, pumps, motors, circuit breakers. I also needed to keep the bottom of the ship pretty flat for both stability during re entry and to get a good coupling on the magnetic launch system that runs up a mountainside.
I had originally wanted to use the NASA type idea for Olympic Mons on Mars, where the volcano is so high, it actually sticks out of the atmosphere. But discussing it with a few folks, you just can't build a mountain that big under Earth Gravity. (Sides slide down the mountain due to the weight, and if they didn't, it would tend to sink into the crust.)
I used the Space Shuttle to get a rough idea of the size and thrust and weight [of the SC]. Basically, it's a two times scale up of the space shuttle, but with fusion rather than chemicals providing power. I'll have to look a bit closer to see if the numbers work out. After all, a two times scale up of a bumblebee can't fly, and I'm REALLY good at making stupid mistakes with my numbers.
The ship's A.I. is much more focused than Helix. If it doesn't affect how the ship will perform or its mission, it doesn't care. Though it could be argued that the ship is just as flexible as most of the robots; not only did it once think it could ignore orders, it's started working on getting Sam hurt ever since Florence convinced it it couldn't kill him.
The SC has a three stage engine system. For intra-atmosphere flight puopulsion is provided by turbofans which is the turned into vectored thrust, providing both lift and thrust. A system the same as a Harrier jump jet.
For that transition stage where the air is too thin for the air turbines, but still deep enough in the gravity well for the low thrust constant boost methods, I went very simple. Water. A steam rocket with a fusion reactor as the heat source. It's also used in space to give extra thrust. Downside is that it is reaction mass, and thus rather limited.
The ship “wings” contain a lot of water. The most energy costly part is getting the ship out of the gravity well, so designed that the maximum amount of water is between the reactor and the cockpit at this time. As the steam drive goes into effect, water is lost and shielding goes down, but not to any unsafe levels. In space, the reactors can be operated at lower power and less shielding is needed. (Yes, spent way too much time with some of the details of the ship.)
For re entry, the ship can just drop into the atmosphere until the air is thick enough for use as reaction mass.
The other way than FTL to get things around is to build them in a system that has factories and then just give them a push and let them drift to the next star system for pick up. When starting terraforming, this is the cheaper way of getting things there until local manufacturing can take over. Takes decades to go from point A to point B, but it's cheap. That's how Sam's ship arrived in the system.
For preservation of the ship's interior, it helps to hold a magnetic field around the ship to deflect charged particles. You don't want to leave a reactor running on its all that way, and with superconductors, you can make some really good power storage cells. The Savage Chicken has one fusion reactor down (500 MW reactor), but still has the 1500 MW/HR of storage capacity that was used during its long slow trip from the system that built it to the system its in now.
Iron Jets. Here I'm using another idea from Nasa. Earth is in the Arm of Orion, a big cloud of iron dust. Once you have nuclear fusion, your problem isn't energy, it's reaction mass. (Yep, keeping it primitive. No reactionless drives here.) Once in space, you can use a set of magnetic scoops to pull in the iron and accelerate it out the back. Free reaction mass. The thrust for this wouldn't be very great, since the iron dust even in heavy areas (like where Earth is) is still pretty diffuse.
By projecting a magnetic scoop in front of the ship, iron and other magnetic materials are pushed in the intakes, accelerated by a magnetic induction driver, and squirted out the back, thus providing low power, but constant thrust. Since this is a ramjet arrangement scoop the ship has to be moving at a sufficient speed to obtain enough 'reaction mass' to work. The teakettle provides that initial thrust. Notice also the exhaust port is located inline with the intakes. Important to obtain maximum acceleration. As for Stardrive, the SC is a purely in-system ship. The D.A.V.E. Dangerous and Very Expensive-Mark named it DAVE when questioned about what he calls his ‘warp drive,' but it was left as just an acronym until Arc Nova ‘named' it. dilation drive is only used on massive transport ships.
Ben Bova pointed out that objects in space acquire a slight negative charge (due to photons removing electrons by Compton Scattering.), so while iron is the stuff I'm interested in for reaction mass, other particles would work too.
The ship is highly compartmentalized. I had thought about the “launch suits” that a shuttle crew wears, but Sam doesn't have a vacuum suit, and Florence went up without one to show unity with the Captain. (Only time it would be faster to suit up than to change compartments would be during the boost phase.) Any accident large enough to take out so many compartments that this is no longer true would take out the ship.
Ships are always a little bit noisy. There's the ventilation fans constantly running, the pumps to keep the reactor cool, the life support systems. Just as long as there are no loud bangs or complete silence, things are usually working as expected.
In micro gravity, leak sealing is kind of neat. Since pressure forces everything to the leak, having “blow out” packs with something as simple as 10 cm by 10 cm thin pads of rubber could seal most expected leaks. Some of the “messier” versions I've seen from NASA use hardening foam.
Most engineering spaces are built with the expectation that only people who know what they're doing will be in there. Not only are things not fitted with “Molly guards”, covers over stop/reset switches or, in this case, things like the self-destruct or power trip buttons a certain amount of Darwinism comes into play. Those are spaces that will little effort, you can open things up that will allow you to kill yourself.
Metal fatigue. This becomes more detectable using superconductive cermets, since cracks would show up as no conductive points to high frequencies. (Same way a Time Domain Reflectometer works.) So ship hull integrity is easy to check. Seal integrity? That's a bit harder. I made the ship with double doors every place where there is a vacuum on the other side, and guess I need to show the “pull down” door that fits on the cargo bay door inside the ship.
Interstellar space is pretty sparse pickings. (Average density of matter in space being 1x10e-27 grams/cubic centimeter). But about a thousand or so years ago, the Earth moved into the Arm of Orion (or Orion Arm, depending on which site you look at). The Arm of Orion is mostly made of iron, nickel, and silicates. To cut to the chase, our solar system is now moving through a dust cloud with an average density of 1x10e-19 grams/cubic centimeter, or 100 million times denser than average interstellar space. We should be in the Arm of Orion for about another 50,000 years. I would love to say I came up with the idea, but the folks at NASA beat me to it with ideas on collecting this dust for station keeping reaction mass for satellites. Just about everyone is familiar with Bussard Ram Jets that scoop up interstellar hydrogen. With the dust available, it becomes possible to get decent amounts of reaction mass without having to go ludicrous speeds.
I used [a size of] 100 kilometers (50 Km radius, or area of 7854 square Km) [for the iron jets]. Now to do a simple trip to Mars using a Hohmann Transfer Ellipse for our path, the distance is 1.43605x10e9 Km. That gives (assuming you can catch all the mass there) 1.128x10e6 Kg of mass. Not a bad haul, really.
So essentially there are not 'thrusters' visible on the outside of the ship, only the common exhaust port. Now since one gets maximum thrust in a linear type mass driver one assumes that the 'acceleration tubes' are straight. This puts them in line with the intakes and the exhaust port. A smaller section of the intakes (which basically cover 80% of the front quadrant of the ship no there is plenty of 'space' are the air intakes for the turbines. By piping off some of the plasma from the fusion engine a MPD turbine connected to a compressor could easily provide the necessary airflow. The high power of this flow would allow it to be ducted into the main thrust tube. The teakettle engine is a bit more tricky as it requires the water to come into close proximity of the fusion core to be superheated. This would mean that it would have to be close to the reactor and to prevent damage to the thrust tube would need to be shielded. All from Ashe, but Mark didn't object, so I'm assuming I just missed it somewhere.
For the Freefall universe, I'm trying to keep the science pretty much what we have today. Easier to write when I understand the underlying physics. So no faster than light communications. If you want to send a message from one place to another, you have to do it by sending a ship. I [also] decided to go with known technology (Cermets, like the armor on the M1 tank) and use “good enough” stuff [for ship construction]. I also like things that are simple, and big ol' diamond plates are simple and effective. (Diamond over titanium. With fusion, power is cheap, and titanium is the seventh most abundant element in the Earth's crust). The hull of the Savage Chicken is a type two superconductor sandwiched between cermet plates.
Fermi One used liquid sodium for coolant. It was a fast breeder reactor run for Uncle Sam and long since decommissioned. For non-breeders, water works great. What you are looking for in a thermal plant is an atom about the same mass as a neutron. Then a collision transfers about half its energy, and slows down the neutron in the minimum number of collisions. (Thermal neutrons in this case are considered to be moving at the same speed as the other molecules at the same temperature.)
The Asimov's reaction mass is expelled from the four small pipes on the outside of the general equipment cylinders. It was a rough design, and I was still kicking around in my head if it would be better to have it self propelled or to use a strap on rocket pack that would be jettisoned before the DAVE drive went on. They're not more obvious because I was leaving myself wiggle room.
Almost every science fiction story has one “magic” bit, usually a faster than light drive. But even with science, we have our bits and pieces that no one knows WHY some things occur, like quantum tunneling and quantum non locality. Must be due to the Cheese Sandwich drives.
The DAVE drive in Freefall is essentially a low grade wormhole. Taking the Einstein/Rosen bridge and combining it with Hawking's theories on time, a perfect wormhole would be timeless since there is nothing to degrade. No entropy, no time. But put matter into it, now you've got time. At least until the matter within reaches thermal equilibrium.
There is a sort of FTL in Freefall. I took what Stephen Hawkings said about time, and put that together with the standard Einstein/Rosen bridge. (1935, Einstein and Nathan Rosen suggest that separate parts of space may be connected by timeless bridges. Otherwise known as a wormhole.) So I played around with this for a bit, and came up with what happens if you lower space time density in an area. Light speed goes up, and to preserve relativity, the rate of time increases. This is where I have to use a bit of “magic”, since while we have dynamic vacuum theory, we currently don't have anyone even making guesses on how it can be manipulated.
To make a long story short, the starships in Freefall make pockets of lower space time density, increasing the rate at which they go through time. From their point of view, they never exceed light speed, and it takes them years to travel from point to point. From the planet based observer, they make the trip in a much shorter time. (Such as a week.) The ships have to be overhauled at their destination, and cold sleep is needed for the passengers to keep supplies down to a reasonable amount. (And also to make them less susceptible to radiation, since cell vulnerability is based on reproduction rate.) Kind of an odd way to make an “FTL” drive, but only one I could even come close to getting the physics to work for.
Mass/energy equivalence causes the rate of time to slow down. If you could do it without being ripped into tiny pieces, the same effects can be done by lowering a person towards a black hole. Gravitational effects, acceleration effects, the theory doesn't care which causes it. On the other hand, less mass energy in an area, the faster time goes. (Stephen Hawkings explains this in “A brief history of time” in far more detail than I can do in a forum.) An easy way to think of it is to take a box made of a material that matter or energy can not pass through, and has no mass or energy of it's own. Make the box one meter by one meter by one light year long. Now take all the matter and energy out from the inside of the box and seal it. This is our old friend, the Einstein/Rosen bridge, in a box for convenient handling and to wave about at birthday parties. Nothing to it, really. The nifty thing about the box is that all the points on the inside of the box are touching. Not because they're actually touching, but because there's nothing inside the box to define space/time. If we were to shoot a photon into the end of the box, it would come out the other side instantly. (This is assuming it hits at the right angle, doesn't tunnel out or collapse into background radiation, etc.) The fun begins when you start to let energy and matter leak into the box.
For all practical purposes, this box can be considered a separate universe. Okay, it's a pretty boring universe, nothing in there. So we'll let a single electron in. Fills up the entire box. (Big electron, but only mass/energy in there.) Now Hawkings has said that time is a measure of entropy, and in order for time to progress, there has to be order going into disorder. With just one electron, there is no interaction, and still no time inside the box, even though something is there. So we'll add another electron with a bit higher energy. Photon exchanges, entropy, we now have time in our little universe. But it soon reaches a stable state, heat death has occurred, and time stops again. But if you add more particles, there is more and more room for interaction, and “time” moves at a slower rate.
Distance will have to wait for another day. I have to admit I'm still a bit confused about some of the aspects of distance. Einstein has said mass creates space/time, but there is space/time where there is no mass. When you accelerate an object, it gains mass equivalence. So can energy be a component of distance, and removing energy remove space/time? Guess it's still the simple questions like “Why is there distance in interstellar space?” still stump me.