The Slingatron: Building a Railroad to Space
The Slingatron: Building a Railroad to Space
A railroad to space using a mechanical hypervelocity launcher to enable large-scale space utilization.
A railroad to space using a mechanical hypervelocity launcher to enable large-scale space utilization. Read more
About this project
Our Vision for a Railroad to Space
We want to open up space for peaceful purposes in a dramatic way by significantly lowering space transportation costs, while dramatically increasing flight opportunities and launch reliability to earth orbit. Most importantly, we want you to be a part of this effort by not only being a backer of this Kickstarter project, but also by being a part of the user community that will grow out of this development effort. A Backer Participation Program in Slingatron Space Applications concept development is described further below.
As the early railroads opened many remote lands here on earth, the Slingatron space launcher has the potential to open the frontier of space on a scale that has never before been possible. It is our intent to develop the Slingatron as an efficient means of transporting bulk materials such as water, fuel, and building materials to earth orbit to enable large-scale space activities for the benefit of the entire planet.
Vehicles in Low Earth Orbit (LEO) have a velocity of about 7.6 km/sec. The Slingatron will work by essentially “slinging” bulk payloads into orbit using a unique mechanical acceleration approach that can launch payloads at up to 7 km/sec, and even higher. A payload launched in this manner will require a launch velocity sufficient to compensate for the small loss traversing the atmosphere, plus a small on-board delta-V capability needed for final orbit insertion and circularization. The latter will typically be accomplished with a small on-board kick motor. The result is a complete landbased electrically powered earth to orbit launcher.
On the occasion of the publication of Derek A. Tidman's textbook "SLINGATRON - A Mechanical Hypervelocity Mass Accelerator", Freeman Dyson had this to say about Slingatron....
We firmly believe this may be the most important Kickstarter project you will ever have the opportunity to back and to be involved with. The Slingatron is a mechanical hypervelocity mass accelerator that has the potential to dramatically increase flight opportunities and reduce the cost of launching payloads into earth orbit, thus helping to make humanity a truly spacefaring species. The Slingatron technology can be incrementally grown in performance and size to ultimately launch payloads into orbit. Our Kickstarter project goal is to build and demonstrate a modular Slingatron 5 times larger in diameter than the previous existing Mark 2 prototype. It will be used to launch in our laboratory a 1/4 pound payload to 1 kilometer/sec. That is about 2,237 mph! If launched straight up at that speed, a payload would reach an altitude of about 51 km, neglecting air resistance. This Kickstarter project is an important next step in the development of the Slingatron because it will provide vital technical information, practical experience, and cost data on what will be required to build a full-scale Slingatron orbital launch system in the future.
Please take a moment to read further about our project and what we intend to accomplish on this first critical increment!
Large scale space activities will require dramatically cheaper and more reliable means of putting bulk payloads into orbit !!
The high cost and high risk of present day space access is a fundamental barrier to large-scale space utilization. Only about 4% of a typical rocket is usable payload - rockets are essentially giant flying fuel tanks carrying a comparatively small payload to orbit. And as we are all reminded from time to time, launching rockets is still a complex risky endeavor.
As an example of current launch costs for what may be the smallest standardized satellite launch you can buy on a rocket, a cubesat with dimensions about 4 x 4 x 4 inch (10 x 10 x 10 cm) and weighing about 3 lbs (1.33 kg) placed into low earth orbit costs between $85,000 and $125,000. Even large payloads can still cost as much as $2,000-$5,000 per pound of payload on existing rockets. Rockets are still a high-risk transportation system. But despite the occasional rocket launch failure, rockets are still the only real way to put anything into orbit at present, and will probably be the only way to put fragile systems into orbit for a very long time. By fragile, we mean people and satellites like the Hubble Space Telescope.
On the other hand, if we are ever to truly break out into space in a big way to do big missions and industrialize space, which will require building large structures in space supporting many people, then we need a different paradigm. We need to transport the bulk building materials and other supplies, such as water and fuels, via a cheaper method. You don't want to use an advanced $60M rocket to deliver tons of water or radiation shielding, when a railroad is what is needed.
Clearly, there is plenty of room for innovative new concepts in space transportation. We're 60 years into the Space Age - it's time to seriously explore alternative approaches to launching bulk materials into orbit !!
SLINGATRON - A New Old Technology
The Slingatron space launcher is an earth-based mechanical hypervelocity mass accelerator. This patented technology can be made large enough to launch a steady stream of heavy payloads into orbit and even beyond. Conceptually, it adapts the old-fashioned sling, but uses modern engineering, materials, and computer controls to overcome the limitations of the old sling. Payloads launched from the Slingatron could range in size from tiny standardized satellites all the way up to multi-ton payload containers, with the most likely first generation space launcher sized for a few hundred pound vehicle. It should be emphasized that the Slingatron does not replace rockets. It complements rockets, freeing them to launch what they launch best. Slingatron is best suited to launch bulk materials such as water, fuel, building materials, radiation shielding, g-load-hardened satellites, etc. into orbit. It cannot launch people or very delicate equipment due to high acceleration (g) loads experienced during the launch cycle. However, bulk materials will account for the majority of mass launched into orbit if we are ever going to establish a major presence in space, whether those materials are launched from the Earth or from the Moon.
Here are examples of missions Slingatron could enable:*
- Low cost and rapid turn-around sub-orbital sounding rocket launch
- Rapid orbital deployment of a low cost global satellite based communications network as well as other large number satellite constellations
- On-orbit refueling of reusable launch vehicle stages to increase their payload launch capacity and overall mission performance
- High volume delivery of radiation shielding for manned deep space missions
- Refueling of robotic spacecraft in a large-scale effort to remove and or recycle orbital debris
- Resupply of manned platforms, including construction and fueling of large interplanetary spacecraft
- Delivery of structures and raw materials for large-scale space based construction and manufacturing
- Planetary defense from earth threatening asteroids by gradually diverting their trajectories
- Low cost large volume earth return of space manufactured products via high volume launch of reentry vehicles
*We would like to hear your suggestions for potential Slingatron missions that would improve life, both on and off earth.
How exactly does a SLINGATRON work?
In the figure below we show two versions of a classical sling. Case A shows a mass being accelerated by whirling it around with increasing frequency but with a constant radius (R) (the length of the string). Case B shows a mass accelerated along a spiral path by whirling it with a constant frequency, but with an increasing R accomplished by gradually letting the string out. The input power from the man's arm in Case B accelerates the mass by pulling it with a velocity component in the direction of the centripetal force acting on the payload.
Case A Case B
In these two versions of a classical sling the payload is
constrained to follow either a circular or a spiral path by a
centripetal force that is provided by the tension in the string. The
payload, and the end of the string to which it is attached, orbit with a
speed or velocity (V) which is proportional to the length of the string
R and the speed of the man's arm gyrating around in the little circle.
In Case A, high speed is achieved by increasing the gyrating frequency
with constant radius R, and in Case B high speed is achieved by
increasing radius R with constant gyration frequency.
Now, if a string with an infinite tensile strength were available, one could stably whirl a payload to a velocity much greater than 1 km/sec, theoretically fast enough even to reach space. However, real strings break under enough tension, and this typically limits the payload’s maximum velocity to about 1 km/sec, depending on the materials and design. Hypervelocity is therefore not achievable using a classical sling for either Case A or B. The Slingatron circumvents this tensile failure limit on classical slings, and makes such hypervelocity payload launching possible.
The Slingatron mimics the Case B above by using a very strong steel track (hence the railroad analogy) formed into the shape of a spiral path that the payload would have traveled with a lengthening string. This spiral launch track is mounted on top of a modular gyrating platform that is capable of gyrating at typically 40-60 cycles per second. The Figure below shows the geometry of the track analogous to the path taken by the payload in Case B above.
The animation below illustrates the basic mechanical gyration function of a spiral Slingatron track:
In preparation for payload launch, the Slingatron is
gradually gyrated up to approximately 40-60 cycles per
second. Once the Slingatron track is cycling at launch speed, the
payload module is released into the entrance of the track near the center of the rapidly gyrating
spiral track. Once within the track, the payload module accelerates and quickly
becomes phase-locked with the gyrating action of the entire platform as a result
of the tremendous acceleration. The strong centrifugal force causes
the payload module to continue accelerating throughout the spiral track. From
the perspective of the payload module, it appears to be constantly
sliding down a steep incline under a very high "gravitational force", which is actually due to the centripetal acceleration. At high speed, the payload slides on a "plasma bearing" film that forms between the bottom of the payload and the surface of the steel track. This plasma bearing provides a very low coefficient of friction cushion which allows the rapid acceleration. When the payload reaches its launch velocity of about 7 km/sec in the last spiral turn, it then launches through a track angled up a hill or other structure to direct it into space.
For those of you who wish to learn more of the physics, detailed mathematical descriptions of the Slingatron dynamics are available through these published papers and presentations (free pdf download).
As mentioned earlier, an entire textbook devoted to the Slingatron has also been published by the inventor Dr. Derek A. Tidman. This 113 page textbook is one of the premiums for some backers, either as a pdf download, or the hardcopy textbook itself.
How will a Slingatron launch payloads into orbit?
Here is a conceptual overview of how a Slingatron would launch payloads into orbit:
- Satellites or a bulk cargo container are attached to a kick motor upperstage forming a payload module. The payload modules are then loaded into the launch rack at the center of the Slingatron spiral track.
- The Slingatron is gradually spun-up to a typical gyration speed of approximately 60 cycles per second. This is done over a period of minutes to ensure that all parts of the track are gyrating smoothly in phase.
- At the specified launch time, a Payload Module is released into the Slingatron spiral.
- The centripetal force from the gyrating Slingatron moves the payload module forward into the Slingatron track.
- The Payload Module rapidly accelerates under the tremendous centripetal force as it travels outward in the ever-expanding spiral track.
- The Payload Module exits the Slingatron at a velocity of about 4.3 miles/second(7 kilometers/second).
- The long thin Payload Module has an ablative nosecone which prevents thermal damage to the Payload Module during its brief (few seconds) flight through the dense layers of earth's atmosphere.
- The Payload Module loses some velocity due to atmospheric drag. This is small compared to its overall launch velocity.
- The rocket motor upperstage on the Payload Module is fired near apogee (highest part of the parabola) to make up the velocity lost from atmospheric drag and to alter its trajectory into a circular orbit around the earth.
- Payload Modules that are not free flying satellites are then captured in orbit by a robotic space tug and delivered to a central Payload Depot.
What are the advantages of a Slingatron orbital launch system?
- System is ground based and nearly completely reusable
- Rapid serial launch capability, one machine is capable of many thousands of launches per year
- Dramatic reduction in payload integration and launch costs via high volume launch rate
- Enables the cost effective use of low cost, mass produced short lifetime satellites
- Expected high launch reliability via overall system simplicity and high launch volume.
- Virtually no rocket exhaust emissions within the atmosphere
- Energy efficient electric motors drive the Slingatron. Most of the energy to reach orbit is just electricity from a conventional power grid.
- Simple robust ground based design of Slingatron enables a high level of maintainability and reliability.
- Launch on demand (short wait for launch opportunities)
- Has potential to be scaled up for launching large payloads
- Slingatron is modular for performance growth
- Ideal for launching bulk cargo
- The payload containers themselves can be designed for reuse as building blocks for large space structures
- An orbital Slingatron can be manufactured from existing, commercially available, highly reliable materials and components.
- Complementary to existing global rocket fleet by freeing them to launch what they launch best
What are the disadvantages of a Slingatron orbital launch system?
- High peak g-loads of up to 40-60,000 g’s during launch limits the type and complexity of payloads that can be launched. Allowing larger diameter Slingatrons, however, can reduce these g-loads in direct proportion to the increase in diameter.
- Special g-hardened satellites will need to be developed for those applications requiring specialized satellite functionality.
- Non-satellite bulk payloads will most likely require orbital capture by a space tug and further processing at a supply depot on-orbit. The cost of these systems must be factored into the overall infrastructure cost of a large-scale orbital Slingatron launch system. These systems will presumably be reusable and enabled by the lower Slingatron launch costs.
- To reduce drag and heating during launch and the brief atmospheric transit, payload modules must be designed to be long and relatively small in diameter thin.
How far along are we with Slingatron development?
To date, three one meter in diameter Slingatron demonstrator machines have been built by the Slingatron development team.
The video below shows the Slingatron Mark II Prototype in operation at about 30 cycles per second gyration frequency. Of course, a space launcher will be much larger and capable of launching at much higher velocity!
We are planning a multi-step development program in which we establish and then achieve specific performance milestones on our path to a full-scale space launcher. This Kickstarter project aims to accomplish the first step!
Technical Objectives for Slingatron?
Our technical objectives for this Slingatron Kickstarter development project are to meet or exceed the following performance goals.
1) We will design, construct, and test a Slingatron with a diameter of about 5 meters and capable of accelerating one pound payloads to 1 km/sec. We will need to achieve 40-60 cycles per second gyration frequency to accomplish this. We will only work with ¼ lb payloads during the basic Kickstarter project and for the demo event, but we will design and build the Slingatron so that later we can safely test launch one pound payloads. During these laboratory and demo tests, the payload will be captured in a tank.
2) We will design the 5-meter Slingatron as the core module of an expandable system to which additional modules can be added later to extend the performance to 2 km/sec or higher. This allows the investment in hardware provided by this Kickstarter project to leverage the construction of higher performance machines without having to start from scratch.
We are proposing in this Kickstarter project to build and operate the next step in Slingatron development - a 5-meter diameter device that will enable a dramatic performance increase to launch about 1 lb at 1 km/s (2,237 mph!).
The Kickstarter demonstration unit will look much like the CAD drawing below which is an extension of the existing Mark II prototype device onto a horizontal plane.
The goal is not only to demonstrate a dramatic jump in performance, but also to demonstrate a modular approach that will make it easier to build much larger systems using the 5 meter unit as a logical building block.
In addition to these technical goals, an additional goal is to establish the Backer Participation Program through a Slingatron Applications website as described below.
KickStarter Funding GOAL and Backer Participation in SLINGATRON APPLICATIONS Development
We invite you to join us as we construct, test, and demonstrate the first step along the pathway to constructing earth's first railroad to space!
Our initial funding goal is $250,000. We plan to use these Kickstarter funds to build a
modular, horizontal Slingatron device that is five meters (16.4 feet) in
diameter and capable of gyrating at 40-60 cycles per second (cps). This
Slingatron will be designed to be able to launch a 0.454 kg (1 lb)
payload at a velocity of one kilometer per second, but will only
be operated with 1/4 lb payloads for the demo. It will take us approximately six months to build and test the demo device.
The culmination of this Kickstarter project will be two-fold:
1) An all-up laboratory demonstration of a Slingatron module launching a 1/4 pound test payload to 1 km/sec, 10 times the previous Slingatron record; and
2) The first Slingatron Applications Workshop to be hosted at HyperV Technologies immediately following the demo event above.
While HyperV Technologies Corp. develops the Slingatron launcher technology itself, we want to also build, in parallel, a community of potential end users and individual contributors to developing peaceful SLINGATRON APPLICATIONS in an open discussion environment. This is where you, our potential backers, can play a participatory role. We plan to launch a Slingatron Applications website for access by backers only, shortly after reaching our Kickstarter goal, which will have discussion forums and online material related to commercial civil end uses of the Slingatron in space.
Backers will have the opportunity to review and contribute concepts for various peaceful applications and missions for which Slingatron can play a key enabling role. We will start out with three topical areas and add to them as new ideas arise both by us and by you, our backers. The first three Application topics will be:
- Asteroid Diversion and Mining
- Orbital Debris Removal
- Large-Scale Space Manufacturing (such as supply depots, orbital shipyards, and other manufacturing facilities)
Future topics will include, among others:
- Lunar-Based Slingatrons
- Large Astrophysical Observatories
- Large Space Habitats & Structures
We are also looking forward to some innovative suggestions from our backer community!
We encourage backers to participate in this open application development as we explore together different approaches to accomplishing important missions in space using the Slingatron as the key enabling launch technology.
We will encourage backers to post original drawings, artwork, video animations, technical analyses - both engineering and physics, and even cost analyses, where possible, for the various space missions. This information will be posted on the website as a central repository for public review and discussion. All contributed material will be considered open source to encourage a free ranging discussion of ideas and concepts. Depending on the level of participation, we will consider beginning an on-line journal on the website, "The Journal of Slingatron Applications", which would include both peer-reviewed and non-peer reviewed articles.
We will update you regularly about our progress via our Kickstarter blog, Facebook, Twitter, and uploaded video of the tests posted to our website and YouTube channel. We will invite select backers and the press to the demo and plan to put the event on live webcam for all backers to experience live.
We have a strong and experienced technical team
We are technical professionals with many years of experience developing and safely testing hypervelocity acceleration technology. Detailed biographical information for the Slingatron development team is available in the right sidebar link near the top of this page - "See full bio".
Dr. F. Douglas Witherspoon is President and Chief Scientist of HyperV Technologies Corp.
Dr. Derek A. Tidman is the inventor of the Slingatron.
Mr. Mark Kregel is a Mechanical Engineer.
Dr. Andrew Case is a Senior Scientist with HyperV Technologies Corp.
Dr. Samuel Brockington is a Senior Scientist with HyperV Technologies Corp.
Mr. Christopher J. Faranetta is Vice President for New Business Development for HyperV Technologies Corp.
HyperV Technologies Corp is a small R&D company based in Chantilly, Virginia USA. Our facility has a machine shop from which our plasma thrusters, high power switches and other advanced technology have been produced. Our 9,000 square foot facility contains two fully functional safety interlocked high voltage/high vacuum laboratories, complete with high voltage charge/dump control systems and high vacuum chambers, as well as other experimental support such as a large rfi/emi shielded control room. This facility will serve as a base for the design, manufacture and special testing of the Kickstarter five meter Slingatron. HyperV successfully completed a KickStarter project, Plasma Jet Electric Thrusters for Space, a few months ago, to begin development of a plasma thruster for use in the space leg of our vision for space for which the Slingatron forms the ground-to-orbit leg.
Detailed Backer Rewards List
A detailed backer rewards list in an easy to read format can be obtained as a pdf download here - Detailed Backer Rewards List
Risks and challenges
As far as the Kickstarter project goal is concerned, the risks and challenges are mainly technical. The main risk is that we might not achieve the performance goal of 1 km/sec. That seems unlikely given the preponderance of data to date, but is still possible, either because the effective coefficient of friction turns out to be larger than expected or because we run into problems controlling the drive motors or getting the system sufficiently well-balanced that we cannot run at high enough gyration frequency. Since we already have fairly definitive friction data for plastic on steel at up to 5 km/sec, friction seems an unlikely technical barrier. Furthermore, controlling the motors appears to be fairly straightforward, although getting all the sensor and control algorithms working properly will be challenging. We have extensive experience doing diagnostics and controls for high voltage experiments, so that seems to be a low probability problem. The issue that might cause some difficulties would be getting the system properly balanced for smooth gyration. Since the velocity is proportional to the gyration frequency, any limit on the gyration frequency, due for example to an unbalanced system, would thus limit the velocity achievable. In the end, the challenge is not so much as to whether it can be done, which is pretty much a given, but whether we can successfully do it within the constraints of the budget and time available. In any case, the odds are very high that we can successfully pull off the project demonstration which is the official goal of this Kickstarter project. At worst, the gyration frequency might not quite reach the goal of 40-60 cps so that the final payload velocity would be proportionally lower. We would still be able to demonstrate a new performance milestone significantly higher than previously. In closing, we should emphasize that we are technical professionals and this is a complex patented technology that should not be attempted by anyone else.Learn about accountability on Kickstarter
Slingatrons are high speed, high kinetic energy, gyrating devices requiring precision design, fabrication, and expert assembly and operation. For safety reasons we do not recommend attempting the construction of amateur built Slingatrons. Please do not try this at home!
Yes, NASA is aware of Slingatron technology. However, we feel that in order to build more meaningful interest, we need to develop and operate a higher performance machine with the capability of scaling to larger sizes and higher performance, i.e. something along the lines of our Kickstarter project demo! Raising general awareness and understanding of Slingatron technology as a result of a successful Kickstarter project should naturally aid that process.
We hope the Kickstarter project demonstration will help create a global community of people who are interested and involved in the future of Slingatron development, and some day even use it to launch payloads into space. Your backer funds will be used to develop and test a modular scalable Slingatron and perform this demonstration. This machine will help us better understand the technical challenges and costs which lay ahead in the development of a much larger orbital launch Slingatron. We are very excited about this project and the prospect of your involvement in this effort to build what will essentially be the first ever “railroad” to orbit, and throwing the frontier of space wide open!
Yes, obviously, as with all forms of transportation on land, sea, air and space, fast and slow, there are potential defense applications of the Slingatron. We are focused on developing a space launch system for civil uses.
The extreme acceleration (g load) experienced by the Slingatron payload during launch would easily crush the human body or any other carbon-based life-form unit.
This is actually an integral part of the unique Slingatron approach. The high g loads are a result of extremely high speed and a relatively small turning radius. The acceleration is given mathematically as the speed squared divided by the turning radius. For our demonstration, we will have a speed of 1000 m/s and a turning radius of about 2.5 m. This gives an acceleration of 400,000 m/sec^2. Divide this by the acceleration due to gravity, 9.8 m/sec^2, and you get about 40,000 gees. What this means physically is that one pound in the payload will actually "feel" like 40,000 pounds.
A kick motor is a small upper stage rocket engine that provides the final acceleration and trajectory correction needed to precisely place the Payload Module into a specific orbit. Any payload launched on a ballistic trajectory from the surface of the earth, such as in the case of the Slingatron, must have its trajectory circularized at the top of its parabola to enter orbit. Depending on the launch velocity from the Slingatron, the kick motor may also need to impart some additional velocity just to reach orbit. Ideally, the Slingatron would be sized so as to minimize the delta-V requirements of the kick motor!
No. A Slingatron is constructed from commercially available high quality materials, as well as many other off-the-shelf industrial grade components. The Slingatron does not use any hypothetical, yet to be developed materials, in its construction. It can be built entirely with existing materials.
For safety reasons and to comply with U.S. laws regulating the export of aerospace technology this project, and specifically the Slingatron technology, engineering details, and know-how, will not be open source. However, we will keep you updated through the Slingatron users forum on our progress all the way to the production and testing of an orbital launch machine. It is our genuine hope that someday you will be able to launch your payload or satellite to orbit via Slingatron.
On the other hand, the specific civil space missions that Slingatron will help enable can and will be discussed in our Backer Participation Forums. These will be civil missions such as discussing how to remove orbital debris, how to divert incoming large asteroids, how to mine near earth asteroids, how to build large habitats in space using building materials launched by a Slingatron, how to build large space observatories, etc. – you get the idea. These discussions by their very nature are open to all to explore and imagine.
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