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The Denver International Peaple Shooter

Sends passengers anywhere on Earth quickly
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(Title deliberately misspelled :)

Synopsis:
For reference, consider this idea as combining elements of "Public: Amusement Ride: Throw me for a Loop (or twenty)" and "Business: Delivery: Ballistic Delivery Service" (but I didn't need that second one to think of this on my own). The goal is to send peaple to distant destinations, no aircraft needed. But spacesuits, heatshields, and paragliders are required! Note that I do know that variants of this idea have been around for a while (possibly as far back as in Robert Heinlein's novel, "The Moon is a Harsh Mistress"), but I also know how to make it work for real.

Details:
This idea works best for high-altitude locations. Denver (Colorado, USA) is located about an hour's travel time (by car) from Pike's Peak, which at 4300 meters is one of the taller mountains in the contiguous (48) United States. Unfortunately for the mountain, we have to reshape it as a perfect cone, or at least install a large amount of structural hardware, to get the effect of a surrounding cone. From the base of this cone to the top of the mountain, (could be more than 4 kilometers because of the angle), we run a two-meter tube. We can move this tube along the surface of the cone so that "base-to-top" direction can be adjusted to point anywhere among the 360 degrees of a circle.

At the base of the tube (and moving with it around the mountain) is the embarkation facility. Passengers are handled not so much on a first-come-first-served basis, as on a "which direction is the tube now pointing?" basis. If it's pointing toward Easter Island and your goal is Tokyo, then you might have to wait a few hours for rotation of the tube, along the cone, to bring it around to the correct direction. But if your goal is Moscow, your wait might be rather less....

Inside the embarkation facility the passengers have to don special space suits. Likely these will be rented, but frequent flyers are bound to want to own their own. The most obvious feature of these suits is its bullet-shaped design, like a giant artillery shell. Naturally, each suit also has some built-in life support, as well as a deployable heat-shield and paraglider. And two or three superconductive magnet-rings, of course.

Since the mountainside tube is two meters in diameter, the special suit can be large enough for a person to sit crosswise. Think about the original Mercury spacecraft in which the United States first sent individual men into orbit -- there used to be a joke that you didn't just crawl into it; you wore it! (Crosswise, I might add.) Well, just because passengers in these new special "pods" don't stand up like you might think, inside the volume described by "giant artillery shell", that doesn't mean we can't call them space suits if we wish. Certainly they will be smaller-diameter than a Mercury capsule, and the passengers are not expected to wear any other kind of space suit. (By the way, "pods" is a good name, too, heh heh heh....)

After being suited and having the magnet coils charged, the passenger is carefully weighed -- ladies can request confidentiality, but the ballistics computers MUST know precisely how much mass is about to be launched. Next, the passenger is loaded into the breech of the barrel of this mountainous gun. The breech space is actually also an airlock, because the tube itself is kept evacuated. After being pumped down, the lock is opened and the multi-kilometer coil gun begins accelerating the passenger. Orbital velocity can easily be achieved by the time the shell reaches the end of the barrel.

At the end of the barrel is a "plasma valve". I was quite surprised to learn that this is actually a workable technology (it was one of my 25-year-old mad ideas that I could never afford to do anything with, to FIND OUT if it was a workable technology). See link. Basically, a strong magnetic field is used to contain a whole lot of lowish-temperature plasma. On one side of this plasma is a vacuum, and on the other side is ordinary air pressure. The magnetic field keeps the plasma from entering the vacuum, and any air from the other side that enters the plasma (mostly its molecules bounce off) promptly becomes plasma, and thus is also unable to enter the vacuum.

So, the speeding passenger is shot right through the plasma valve at the end of the gun, as if it was no different from the air molecules beyond. Really, there isn't much difference, especially at that speed! Such speed is also why a high altitude location is very desirable for this idea. There will be a significant bump experienced by the passenger when leaving the vacuum in the barrel and entering the air at 4300 meters of altitude. However, when moving at perhaps 8km per second, the passenger will pass beyond the upper limits of the Earth's atmosphere in perhaps half a minute, depending on the trajectory angle. Some appropriate (and easily replaced) ablative heat shielding in the conical end of the space suit should prevent any overheating problems here.

The velocity imparted to the passenger depends entirely on the destination, of course. A pure and simple ballistic path will follow a Great Circle route, until atmospheric re-entry occurs. Pointed southward, a comparatively low-power shot could send a passenger to Tucson, Arizona (US); a more powerful shot could reach Easter Island; still more power would send someone to Antarctica, and sufficient power could even reach Moscow. (The Soviet Union first came up with that last idea, only travelling the other way; they called the notion of sending nuclear missles to the US by going over the SOUTH pole "FOBS", for Fractional Orbital Bombardment System.)

A problem I mentioned in an annotation to the "Throw me for a Loop" idea was that the superconducting rings need to be discharged before they warm up enough to explode. In THIS scenario, the solution to that problem is to use those rings as energy-storage devices, essentially batteries that power the spacesuit. The passenger will take up to 90 minutes to reach the desired destination (going southerly from Pike's Peak, one could reach Calgary in Alberta, Canada, in less than 90 minutes) -- naturally, there must be things to do while in flight, and almost all such things will involve energy expenditure that has to come from somewhere, such as the superconducting magnet-rings. Not to mention the needs of the life-support system, of course. By the time the rings have warmed up dangerously (a small in-suit supply of liquid nitrogen would be appropriate to delay that), they will have too little remaining energy to explode as superconductivity is lost. Draining their power in sequence is, by the way, the most efficient way to implement this idea (the liquid nitrogen will last longer when it has fewer rings to keep cool).

It is logical that since a given destination attracts multiple travellers, it will be efficient to design multi-passenger suits. The generic label of "PODS" is appropriate, for Partial-Orbit Delivery Suit(s), as several peaple may be lined up inside, in a manner vaguely reminiscent of bobsled riders (but actually spaced farther apart, in appropriate acceleration seats). And, need I mention the likelihood that certain couples will catch a bus from Denver to Pike's Peak, deliberately rent a 4-person PODS, and request a full 90 minutes of round-the-world transportation back to Denver?

As atmospheric re-entry occurs, the PODS first deploys some vanes to catch the first wisps of air and reorient for flat-end-first descent. After turnaround, the suit deploys (from its base area) an umbrella-shaped heat shield of ablative material. It may possibly even be deployed umbrella-fashion. We want this umbrella to be rather deeper than wide, because such a shape will better protect the passenger, and, when the mass distribution is considered, is also self-stabilizing with respect to its high-speed interaction with the atmosphere. Note that I am deliberately specifying ablative materials instead of more resistant stuff like space shuttle tiles, because tiles will almost always be rendered worthless by the crunch-down at landing, and if you have to replace the heat shield anyway, you might as well go with the cheaper stuff.

When airspeed drops enough, the PODS can now fold up its umbrella and deploy the large inflatable paraglider (using saved boiled-off formerly-liquid nitrogen, of course), possibly preceded by a drogue chute. Radars and computers and Global Positioning System equipment are small enough, and computer software is advanced enough, that a completely automated landing should be possible, almost exactly on target, every time.

Depending on how many International Peaple Shooters are built, it could be reasonable for all the rented PODS to be jointly owned by the launch organizations, in a manner not unlike the status of today's international cargo containers (they have a standard design and are freely shared among shippers). Thus all just-landed PODS need only be ordinary-transported only as far as the nearest International Peaple Shooter. Certainly it is reasonable to expect that as soon as the first one is built (I'm assuming near Denver) and proves its value, others will be desired elsewhere.

As mentioned above, ideas like this have been floating around for a while. The biggest drawback has been the air that gets in the way during the acceleration of the PODS. The shockwave of displaced air can destroy the acceleration coils! But the recent proving of plasma valves, in allowing a completely evacuated acceleration tube, is what will finally make this idea practical. Thus NASA could be approached for funding, and possibly also the Army and the Air Force. Certainly both NASA and the Air Force have plenty of things they'd like to send into orbit more cheaply than by rocket, and it is well known that something like an International Peaple Shooter most definitely does not have to be limited to mere suborbital shots.

Why did I mention the Army? I'm sure my Mad Scientist aspect had something to do with it. See, the Army is in charge of artillery weapons, right? Just think of all the conventional munitions that were recently transported by air from the U.S. to Iraq. Now re-think that operation in the future: Initially, special PODS transport and release large numbers of "bombs" that actually are radar-seeking missiles. Then Remotely Piloted Vehicles fly in from some neighboring region, perhaps from Naval vessels, and are used to shine Laser Target Designators at various other sites. More special PODS arrive, now carrying multiple smart bombs that are dumped at altitude, letting them seek their designated targets. Ordinary bomber aircraft are no longer needed! The less expensive PODS are expended, and no major airplane experiences any wear-and-tear or risk of damage by anti-aircraft fire. Pilots don't get worn to a frazzle, either. Not to mention that the "supply train" for the bombs in this case is entirely internal to the United States, so there are no foreign ammunition dumps to build up across weeks of transport time, and then to guard against terrorists (stuff that the Army is in charge of). All this major savings in time, manpower, and equipment-wear ought to be worth a significant contribution by the Army to the construction of the Denver International Peaple Shooter.

Vernon, Oct 10 2003

Plasma Valve http://www.bnl.gov/...003/bnlpr052803.htm
I did too think of this independently, a whole bunch of years ago! If I recall right, I had just encountered descriptions of coil-gun space-launch systems, which included the problem of atmospheric shock waves against the coils as the accelerated object passes through. So I knew the acceleration needed to be done in a vacuum, and I knew there would be a problem at the end of the tube...thus the plasma valve (I didn't call it that) is the key to making this idea work for real, now that we know such valves can actually be made. [Vernon, Oct 04 2004, last modified Oct 21 2004]

The origin of Murphy's Law http://www.ignobel....murphy/murphy0.html
Colonel Stapp showed how tough the human body really is. [Vernon, Oct 04 2004, last modified Oct 21 2004]

Denver's not the only place, of course http://www.infoplea...m/ipa/A0001798.html
A list of possible Peaple Shooter sites in the U.S. [Vernon, Oct 04 2004, last modified Oct 21 2004]

More possible sites http://www.infoplea...m/ipa/A0001771.html
Not to ignore the rest of the world.... [Vernon, Oct 04 2004, last modified Oct 21 2004]

[link]






       Vernon, you just been to Six Flags or started taking a new medication or something?
DrCurry, Oct 10 2003
  

       Can anybody be bothered to do some calculations? I want to know what the accelerations would be like...   

       Moving the tube around 360 degrees doesn't sound likely to work, maybe we could have four or so big(wide) fixed tubes and use magnets to determine the exact direction the flyer leaves in.   

       Does the tube really have to be 'full' of vacuum? Might it not make more sense to keep the whole thing at high altidude air pressure?
RobertKidney, Oct 10 2003
  

       peaple? is that some sort of fruit?
Eugene, Oct 10 2003
  

       So why exactly is the title misspelled ?
riskyrisk, Oct 12 2003
  

       riskyrisk, you may regret having asked that question. I was having fun with words; for example, there is a thing called a "pea shooter" (most likely a suitable-diameter drinking straw being misused). And there is also a reasonably well known phrase concerning "peas in a pod"... Changing the word "people" by one letter, to bring up such associations, seemed pleasantly humorous. ALSO, however, I had the more pragmatic reason of trying to dissociate the phrase "people shooter" from its most common interpretation....
Vernon, Oct 12 2003
  

       Nice! I like it. About the army part, I am in doubt however: having a bomb hit a wall of air at 8kms-1, is that wise? (unless on purpose - the so-called Thouroughly Self Destructing Launch Installation)
moroder, Oct 12 2003
  

       moroder, I specified that the bombs would be sent inside specialized PODS. They should be fine.
Vernon, Oct 12 2003
  

       reensure, the plasma valve does not especially suck in any air. It actually acts more like a barrier, with air molecules bouncing off the trapped ions. Only if the bounce happens to be especially violent would an air molecule itself become an ion, and thereby become trapped by the magnetic field.   

       RobertKidney, it could be that I have erred in describing the launch tube as being only a few kilometers long; I seem to remember prior coil-gun writings describing longer ones, just to reduce the G-forces experienced during launch. Sorry. Still, it could be possible to modify the design a bit, such as including a complete tubular ring around the base of the mountain, as a place for gradual acceleration, before taking a branch route that starts as a spiral up the mountain, and ends as a straight shot. Next, it really is easier to be able to aim directly toward the destination, than to rely on fancy maneuverings of the PODS to compensate for a fixed shooter-barrel. And, while I described things such that a 180-degree rotation could be workable, in the long run it saves energy to not frequently need to deliver things more than halfway around the world. I mentioned the south-to-Moscow route simply because it was both possible and offers a time-savings to anyone in such a hurry as to pay a higher delivery price, than to wait for the entire launching assembly to be rotated so it aims northward. Overall, I would expect this transportation facility to be almost constantly rotating either in the clockwise or the counterclockwise direction, around the mountain (say, one whole turn per day). Just like ordinary air-travel routes, where you can catch planes to certain destinations only at certain times a day (sometimes only once a day), it is reasonable to think of this facility as offering any destination on Earth, once a day at the cheap rate, and one other time a day at the more expensive rate. Finally, concerning your question about keeping the tube entirely evacuated, this really is the most energy-efficient way to accelerate the PODS. Why waste effort shoving air aside (which also causes shock-wave damage inside the tube), when it can be avoided, up to the moment the plasma valve is reached?
Vernon, Oct 12 2003
  

       Well you waste some effort but it also stops the sudden decelleration when your passenger hits the air. And we want the passenger to be at least a little comfortable.   

       Are you sure a giant rotating tube is not a bit too optimistic from an engineering perspective?
RobertKidney, Oct 12 2003
  

       Regarding the shock of entering the air at the end of the barrel, this will depend rather significantly on the mass of the PODS. The more massive, the less effect that "wall" of air will have. Also, it is conceivable that some means be employed to shock that air into motion even before the PODS arrives. A blast of laser light, possibly. Then the shock of impact by the PODS will depend on the relative velocities of PODS and air.
Vernon, Oct 13 2003
  

       I like it! But I'm still curious about the acceleration factor. It would be unpleasant to have to mop the passengers from the pod on arrival.
PauloSargaco, Oct 13 2003
  

       PauloSargaco, it is fairly well known that people can easily handle significant short-term accelerations. Consider two football players rushing into each other, for example. I once read of some curious researchers outfitting these guys with accelerometers, just to study the intensity of those collisions -- 25+Gs! And other work has also been done (see link).
Vernon, Oct 13 2003
  

       RobertKidney, no, the description is workable with present technology. Consider the TransAlaska Pipeline, for example, as an actually larger-scale construction project with a similar-sized tube. For this one, at various heights, regularly spaced along the mountain, would be placed ring-around-the-mountain guide-tracks. That work would be minimized if the mountain was physically more conical. (If Mt. Fuji in Japan wasn't considered sacred --and if it was an EXTINCT volcano-- it could be a practically ideal ready-made International Peaple Shooter site.) The launch tube rests on every track at a single point. If a tubular acceleration-ring-around-the-base-of-the-mountain is needed, then that ring will have its own guide-track all to itself. Then all that is needed are various computer-controlled motors to drive the tube sideways along all those tracks, more quickly at the mountain base than at its peak, to keep the tube straight. The acceleration coils built into the tubes would get their power from those same ring-tracks, via sliding contact points, like electric trains. This IS workable!
Vernon, Oct 13 2003
  
      
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