Q: What provides lift or centering?
High-Temperature Super Conductors produce a levitating force know as the Meissner effect. Further, the magnetic suspension is an area of proven art in maglev train technology. In this instance, it is necessary to combine these fields simultaneously with those from quench drive. Multiple possible configurations have been identified. Two leading configuration candidates are Electrodynamic Suspension (with the permanent magnet sub-variant known as Inductrack) as is used on the Japanese MagLev system and the Super Conducting loop design from Dr. James Powell.
Q: Can the hypersonic forces and sonic boom be managed?
Yes. Calculations on heat flux stagnation point and stability from Dr. James Powell and expert opinion by Dr. Graham Candler strongly suggest these are likely not showstopper issues even above the 5 km/s velocity targeted. The delivery cylinder is, after all, a heavy-duty, not lightweight object. From an engineering standpoint, these issues were worked out in the 1970s for the DoD concerning returning ICBM warheads at hypersonic speeds to various altitudes, including close to ground level. While carbon ablative solutions are most likely workable, other newer material technologies may prove to be a lower cost for this non-reusable item. Until sufficient altitude is reached, the sonic boom will undoubtedly require installation in a very remote location. Counterintuitively, the physics of the pressure wave creation in hypersonics are such that larger diameters and more extreme hypersonic velocity do not create dramatically more overpressure.
Q: How is cooling and excess heat managed?
Commercially available cryocoolers are sufficient for the operation of various material solutions in the high-temperature superconductor realm. Importantly, this temperature is reachable by liquid nitrogen rather than the much more expensive cooling requiring liquid helium. While cooling the vacuum tube, in general, is likely to be a somewhat straightforward engineering task, one aspect of heat management is more difficult. That is the heat dissipation performance in the carrier sleeve or armature. Much will depend on the level of efficiency that can be achieved. Reservoirs of liquid nitrogen can be carried and bled into the vacuum tube as used, and while this appears sufficient, it is another question that needs further research. Also, it is possible that modeling will show forces generated by permanent magnets are sufficient to trigger the quenching required. In that case, heat management requirements will be dramatically reduced.
Q: What are the likely diameters, lengths, weights, and velocities of the proposed design?
At this point, answers are just arbitrary selections of possible dimensions. An important aspect of the research needed is to explore the tradeoffs in various dimensions. For instance, the physics of magnetic fields are greatly helped by larger diameters, but the square area under the crushing (expansion) forces also grows with diameter. Much can be done to relieve the engineering challenges from higher power and higher acceleration approaches with a longer launch tube, but at some point, even in a public-private partnership, sunk capital costs grow so great as to make the project unworkable.
Q: What is the Tyranny of the Rocket Equation?
Getting on orbit isn’t how high you lift, but how fast you go if you want to stay in orbit anyway. Every gram of freight on-orbit must first have been lifted and accelerated to an enormous speed known as orbital velocity. (17,500 + MPH) The fuel that lifts and accelerates that weight must also be lifted and accelerated, and in turn, the fuel that lifts the fuel must be lifted and so on. It’s a vicious circle. The engineering truth is, rockets mostly lift and accelerate fuel to lift and accelerate fuel. Once you are in orbit, you are already most of the way to the moon or other far distant places from an energy needed perspective.
Q: How is the Sabot recovered?
Actually, we don’t use the term Sabot, which refers to a protective container that exits the barrel or launch tube. Importantly, the shuttle sleeve (armature) that carries the delivery cylinder uses the last 10% of the launch tube to de-accelerate by reverse polarity while the delivery cylinder continues and exits the launch tube.
Q: Doesn’t a fixed guideway limit your access to a various orbital inclination?
Of course, the launch tube is set to a single inclination for all launches. The important point is that the project dramatically changes the cost of raw materials, including fuel, to a low earth orbit. With the potential to reach $1 per pound of variable or incremental cost to LEO, orbits could be economically adjusted as needed after orbit is achieved.
Q: Are the G forces from acceleration so excessive as to be unworkable?
No. Importantly, we are talking about raw materials, liquids, roll stock, prefabricated construction components and powders for 3D printing. See the downloadable simple kinematics calculator to look at longer runway (vacuum tube) lengths, gentler upward curves, and lower release angles. This, combined with speeds below actual orbital velocities, appears to keep forces within the range of existing electromagnetic technologies.
Q: How are the delivery cylinders and their final boost rocket motors deorbited and recovered?
The delivery cylinders are not intended to be recovered from orbit. Unlike rockets with their need for expensive minimalist construction, the delivery cylinders are low-cost heavy-duty containers and themselves, a source of useful material on orbit. The solid rocket motors for final insertion and orbital circularization leave both a shell and rocket nozzle, also useful on-orbit raw materials.
Q: Is there a market for this amount of raw material on orbit?
We certainly think so. It is hard to overstate the importance of truly low-cost access to low earth orbit. Most of the world’s great innovations have been about cost reduction. The Railroad, the Panama Canal, and Containerized Shipping are three examples of transportation that transformed the world.
Truly low-cost access to space for raw materials enables on-orbit construction for manned exploration and the solar system settlement. This will certainly require habitats with greater mass (e.g., rotating structures and shielded structures) necessary to mitigate the already known debilitating health effects of weightlessness and radiation exposure. In fact, the pursuit of all the great space opportunities, unlimited raw materials from the asteroid belt, unlimited clean energy from space-based solar, protection from cataclysmic planetary loss, geoengineering to mitigate climate change, orbital debris mitigation, the building of habitats on the moon or in near-earth orbit, or maintaining the strategic high ground all require a massive transfer to orbit.
Q: Can the necessary vacuum levels be achieved and maintained?
Preliminary estimates of vacuum requirements appear to be well within the capabilities of commercially available systems. Note the rendering above specifically allows for a much larger carrier sleeve than the delivery cylinder to allow for pass-through concerning pistoning effects.
Q: How will the launch tube be closed to maintain a vacuum but opened as needed?
Some combination of mechanical closure and multiple membranes (i.e., each separately spaced film ply holds back a percentage of air pressure) appear adequate to the task. Air pressure in the vicinity of the opening can be further reduced with steam injection. There is some conjecture that a magnetohydrodynamic solution could provide assistance, but early evaluation suggests the contribution would be slight.
Q: Can the launch tube and carrier sleeve be made strong enough?
Certainly, the crushing and expansion forces are large. The early evaluation suggests they are within the capabilities of modern materials such as carbon fiber. Lowering energy levels reduces acceleration and crushing/expansion forces, but at the penalty of greater sunk capital cost of a longer launch tube.
Q: Will the economics of construction be affordable, and operation be truly low cost?
It appears so. A public-private partnership seems to be a necessary approach. There’s little doubt the upfront capital costs will be extremely high and require the project to be de-risked in stages. Ultra-low operating cost is a primary design driver. Further, as an electromagnetic approach bypasses the tyranny of the rocket equation, it limits itself to raw materials (roll stock, powders, liquids, and prefabricated construction pieces), and does require the significant challenges of deorbiting to be managed, ultra-low operating costs are certainly plausible. In summary, we know that the physics of this approach makes sense and holds out the promise of great economic advantage through an ultra-low variable or ongoing operating costs. Work done to date by the leading experts in the field strongly suggests this approach is plausible and feasible.
Q: Are there other ways to accomplish electromagnetic launch, other than with a quench launcher needing high-temperature superconductors? Is the quench technology the only method that will work?
The Quench Launcher has the most workable design. There are several other ways. Each has advantages, and each also has difficulties that appear to make them unsuitable. The key is to understand that you are applying enormous amounts of power to large masses, driving them to ultra-high velocities in short distances. (yes, ten miles is short.) And, if you are to do so in a series of short pushes or pulls, as with most electric motors, some method must be found to switch on or off that high power quickly and repeatedly. It might be an overstatement to say the quench launcher is the only approach that will work. It is, however, the one that appears feasible. Maybe future discoveries will make other methods workable, or further research will improve through a hybrid of approaches. Each of the other launcher approaches is described below.
The Rail Gun
The simplest of all the designs is just a projectile (armature) located between two rails. As power flows from one rail through the projectile, a force, known as the Lorentz Force, pushes the projectile forward into the other rail. Critically, and unfortunately, the rails and the projectile have to be in physical contact for the system to work. At high power levels and high speeds, the arcing, plasma, and wear creates limits on the number of times such a launcher can be used without rebuilding. In fact, the DoD quietly shuttered their research effort into high power, and high-speed rail guns as the issues with robustness do not appear to be resolvable.
The Induction Launcher
The Induction (or traveling wave) Launcher: This wonderful technology is the basis of most electric motors today. Higher and higher frequencies of the AC lead to faster and faster speeds. Unfortunately, there is no known way to switch the very high current levels needed at the very high frequencies necessary to reach the high velocities required.
The Multi Coil Solenoid Launcher
A series of coils or solenoids, in theory, could push a launch package forward, each giving another push to higher and higher velocities. The power needs to be stored so that it can quickly dump into each coil when needed. Batteries do not release power quickly enough, but many thousands of giant capacitors would possibly suffice. As with the Induction Launcher, the switching problem is a showstopper. A good way needs to be found to release the power from each capacitor, exactly when needed to each coil, and of course, this varies with the speed of the launching mechanism. Unfortunately, there is no known way to do this. Further, there is a concern with putting that much energy into pushing/compressing a launch carrier. Pulling, (it is, after all, a solenoid) while a better choice for material reasons is not workable as there is no good way to dissipate (switch off) the power in the coil at the speeds necessary. In effect, the HTS Quench Launcher is a solution to these problems and is of the Multi Coil Solenoid family.
Q: Wasn’t the military unwise to invest so much in rail gun research?
We don’t think so. Even though it’s hard to be a rail gun fan at this point, you have to remember there was no switch option when that technology was selected. Their priorities were tactical, so things like short barrel length and gun slewing (moving the barrel to aim) were important. A great deal was learned in the high energy physics arena from this early research.
Q: Will the high-temperature superconducting quench switches operate at high enough power levels and dissipate (switch) energy fast enough to achieve the 5+km per second exit velocities targeted?
Preliminary work funded by DARPA suggests the answer to this question can be yes. More dynamic modeling work on novel designs, particularly concerning robustness in repeated use, needs to be done to answer the question fully. The speed of quench and dissipation of the magnetic field is paramount, but so is robustness in repeated use, therefore providing low operational cost.
Q: Are there commercial efforts to pursue electromagnetic launch?
Yes there are. If this is an area of interest for you or your organization, please contact us.
Q: Are other countries exploring electromagnetic launch?
Yes, in particular, China. When China attended their first IEEE International Symposium on Electromagnetic Launch in 1998, a few individuals attended. Most attendees were from the United States, Europe, and Japan, although the meeting was in Scotland. Two years later, at the next event, many more individuals attended from China, and their leader shared EML’s selection as a national priority for China. EML became the priority they promised, the engagement of thirty Chinese Universities followed. At the 18th annual IEEE symposium in 2018, of the 376 abstracts received, 301 were from China. More, by far, than any other country. Presumably, from national strategic implications, visas for travel to the symposium became difficult to acquire, and descriptions of China’s research efforts became, to put it nicely, not very enlightening. The EML program in China proceeds at a size and pace greater than anywhere else in the world. The IEEE international symposium on Electromagnetic Launch Technology ended after 2018.
Q: Won’t a quench launcher with miles of high-temperature superconductor be too expensive to build?
Maybe. The cost of HTS materials continue to fall, and it is now manufactured in mass quantity to supply industrial needs such as laboratory equipment future MRI imaging machines. Certainly, an EML system will be in the billion-dollar class of machines and will need HTS production scaled to new and higher levels. Some argue that this project should be pursued as a multi-nation international project beyond the need for a public-private partnership.
Q: We hope this doesn’t sound rude, but this seems so fantastic. Is this really going to work? Really?
We get that question a lot. Actually, the answer is that it is 100% certain to work. It is, after all, just a solenoid in a vacuum tube. It can’t not work. A better question is, “will it work well enough to fulfill the promise of truly low-cost access to space”? The answer to that question is only, sorry to say, probably. The engineering is really tough. There are huge forces involved. After all, you are accelerating a lot of mass to ultra-high velocities, and the system needs to be so robust you can use it over and over, maintenance-free. Something that robust is probably the hardest part. Look at it this way, suppose the chances were 50/50. And you won’t know until you try. But, if you are successful, you enable low cost clean renewable energy, exploration and settlement of the galaxy, access to unlimited raw materials, and the strategic high ground. The juice is definitely worth the squeeze.
Q: So, is Electromagnetic Launch a competitive threat to Space X’s Starship or Blue Origin’s New Glenn Rocket?
Not at all. The reverse is the case. G forces and engineering practicality limit EML to raw materials and small diameter container sizes. With low-cost raw materials available on-orbit, these great rockets could bring human cargo, delicate cargo, oversized cargo, and complex machinery to orbit to assemble the great ships and habitats needed for humans to venture out into the solar system.
Q: What about the upfront capital costs?
This needs to be a public-private partnership. The government’s unique long-term and strategic perspective allows it to consider a project with high up-front costs but world-changing potential. Think about large particle accelerators, or the Panama Canal, or an aircraft carrier. Traditional private capital ROI’s are not the correct model for these types of projects.
Q: Won’t the costs to get to orbit with Space X and Blue Origin get so cheap such a launch system won’t be needed.
Maybe, actually, we hope so, but it doesn’t look like it. Let’s start by thanking the entrepreneurs and engineers that have brought down the cost of rocket transport to low earth orbit so much. Not long ago, it was $10,000 per pound to send something into space. Now, thanks to reusable rockets, companies with high performance and risk-tolerant cultures have brought those costs down to as little as $1,000 per pound. Their goals are to get to even lower numbers. No one really knows just how low they will get. Much depends on the idea of mass production of these rockets, something Elon Musk himself says is 1,000 times harder than just making one in the first place. And, the goals are dependent on reusing these machines over and over, like an airplane. This, even though they will be exposed to some of the highest pressures, temperatures, and stresses known to modern engineering in a vehicle designed to be as lite as possible. How many uses before a rebuild is necessary is not yet known but is a source of serious concern. Many think they will get to $500 per pound. EML technology is estimated to have costs of $3 per pound to low earth orbit.
Q: SO ARE YOU SAYING THE DESIGN SHOWN IN THE RENDERINGS AND ANIMATIONS MIGHT JUST WORK?
No. What we are showing in the renderings and animations are artists concepts to get across the general idea to the public. Working designs that anticipate solutions to the quench drive challenges would need to show:
- Adequate cooling for both the launch tube and the carrier sleeve
- Design to apply forces uniformly across the entire carrier sleeve or account for tensional strength needed if end only driven
- Design for sufficient levitation or packaging centering
- Design for displacement of the magnetic fields (current) from drive coils once quenched
Q: IS THE COST OF COMMUNICATION, GUIDANCE AND CONTROL EQUIPMENT INCLUDED IN THE ESTIMATED COSTS FOR EITHER THE DELIVERY CYLINDERS OR ROCKET MOTOR CYLINDERS?
No, and frankly it needs to be. We do not suppose that that world should accept a high volume of heavy freight added to imprecise orbits. Discussions are ongoing as to the best way to manage this. Our key economic measure is all in operating cost per pound to orbit. So, this capability with a low cost per delivery unit with useful upcycling or recycling opportunities is an important design constraint.