The Slingatron concept, via HyperV
Last year, HyperV Technologies successfully crowdfunded plasma jet electric thrusters intended for use in spacecraft. Now, the Chantilly, VA-based company, founded by Dr. Doug Witherspoon with Chris Faranetta, Dr. Andrew Case, and Dr. Sam Brockington, aims to build a space railroad called the Slingatron.
What exactly is a space railroad? Well, according to HyperV, it is Earth-based and works on a fairly straightforward product of mechanical engineering—specifically, the good old-fashioned sling.
"The Slingatron space launcher is an earth-based mechanical hypervelocity mass accelerator," reads the company's Kickstarter project description. "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."
Essentially, the Slingatron would be an alternative to rockets. It could launch tiny satellites to "multi-ton payload containers" carrying water, fuel, building materials, for example, into orbit. The advantage to launching via a Slingatron is that it is reusable and could be launched thousands of times.
HyperV's Mark II Slingatron, the first attempt at a semi-modular design for launching a heavy sliding payload. It accelerated a 1/2lb payload to 100 m/sec. A plastic lined steel block slid along the spiral steel track at 224 mph. (Image courtesy of HyperV)
The space railroad would be a heavy duty metal track designed to replicate the path that a payload would travel on the lengthening string of a sling. This metal track would then be mounted on a gyrating platform, which would be capable of gyrating 40-60 cycles per second. In preparation for launch, the Slingatron would begin gyrating up to 40-60 cycles per second.
Once it reaches that threshold, the payload (satellites, water, food, building materials, etc.) would be released near the center of the spiral. From there, the payload module accelerates until it becomes phase-locked with the gyrating platform, and continues accelerating along the spiral track due to centripetal force.
"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," reads HyperV's description. "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."
HyperV have built and tested two different models of the Slingatron—Mark I and Mark II. The Mark I featured a spiral launch track, but used a steel ball bearing, launching it at 152 m/s. In the Mark II, HyperV launched a 1/2 lb plastic-lined steel block so that they could get it to slide instead of roll. The video below shows the Slingatron Mark II in action. The damned thing blasts the steel block through a piece of fabric, then kicks up some dust in the background.
I posed some questions to HyperV Technologies co-founder Chris Faranetta to, amongst other things, get a clearer picture of what a launch would look like, and to see if a human could withstand it.
Motherboard: If you hit your fundraising goal, HyperV will presumable build more robust prototypes, no?
Chris Faranetta: Yes, we will have to build a series of machines, and each machine would have the ability to launch heavier payloads at faster velocities. An important feature of our next five-meter machine is that it will be modular, so that we can grow it into a larger diameter with a tight control on cost.
How big would a full-scale Slingatron have to be?
We estimate about 250 to 300 meters/985 feet in diameter for a machine that is capable of placing payloads in low earth orbit. We will have a better understanding of this as we build larger machines and create tighter computer models.
What are the biggest engineering or other technical challenges?
Some of the technical challenges are issues like: 1) Building and operating an orbital launch machine above gyration speeds of 40 cycles per second, 2) Getting people to understand how the Slingatron works, 3) Developing satellites which can survive g-forces above 40,000 gs, and 4) Developing rocket motor upper stages which can survive g-forces above 40,000 gs. To tackle these technical issues we gain experience from operating and using the smaller Slingatrons as payload R&D platforms.
If you had funding right now, how soon could you have a full-scale model built?
We will have a good idea of cost and schedule after we build and test our five-meter machine.
Would this be able to shoot humans into orbit?
No, never. The Slingatron would crush a person into pudding at launch. This is why the Slingatron will never be able to fully replace rockets, which are needed to launch people and complex spacecraft.
Why isn't anyone else working in this area; or, are there people doing this sort of R&D?
It is a very unique idea derived from the ancient sling. As far as I know we are the only people working on a machine of this type. Would you ever consider that a machine based on a prehistoric technology could be capable of launching payloads at hypersonic velocities? (FYI: the Slingatron is patented.)
If one were to watch the launch, how would it look relative to a rocket launch?
Here is a hypothetical launch sequence:
A. Sirens sound, a voice comes over the PA and announces "clear the Slingatron service area 30 seconds to gyration start!"
B. The Slingatron slowly begins to gyrate at first, gaining speed with each gyration.
C. As the Slingatron gains speed the launch announcer calls off cycles per second (CPS) in tens. "10 CPS", "20 CPS", "30 CPS", etc.
D. By now the Slingatron would be a blur of gyrations accompanied by a whirring noise.
E. Once the desired launch speed is reached the announcer would then call off: "Holding at launch speed 30 seconds to launch window"
F. Then the announcer would give a count down to the desired launch moment.
G. The payload would shoot out the end of the Slingatron leaving a contrail of ablative material gas as it arcs into the sky and out of sight.
What would you like to use the Slingatron to launch?
I would like to use the Slingatron to launch and maintain a constellation of satellites that would provide global, low-cost and high-speed communications.