Monthly Archives: August 2017

Using Inverse Rail Guns for assisted space launch

Following on from the last article on skyline hypersonic travel, Carbon Devices will shortly announce a future space launch system with variants covering a wide range of capabilities. These will range from ultra-cheap launch of lightweight satellites into sub-orbital trajectories up to full orbital launch of large satellites or spacecraft with human crews. The system relies on novel carbon materials only in development today, but that will be routinely available in a decade or two. Once they are, this new system will offer space launches orders of magnitude cheaper and safer than current space launch systems and avoid the environmentally damaging emissions or water vapour in the high atmosphere associated with primitive rocket technology. With far lower launch costs and improved safety, the space industry will flourish.

In the next few posts, several inventions will be disclosed that may be used in our launch systems and weapons. In this article, we explain the first of those, a new technique for driving a tape through a motor at high speed using only electricity. It is related to the rail gun, currently the highest powered artillery system in action, with today’s guns able to launch 10kg metal slugs at over 2km/s, with energy of around 32MJ. By comparison, the Carbon Devices inverse rail gun will be able to launch 60kg slugs at over 50km/s and that is just the scaled down land-based variant. If you believe as we do that the route to peace is to talk softly but carry a big stick, then this is one of our big sticks. We need to learn to talk more softly to each other, because future battlefields will use weapons hundreds or thousands of times more powerful than today’s. The gulf between conventional and nuclear weapons will fully close by mid-century. This pic is a crude example of a fairly modest space weapon with a short tape. Even this would have 3TJ energy, about 100,000 times more than today’s rail gun and 0.75 kilotons of TNT equivalent. This version would only work in space but that’s where some battles in future wars will be fought. Anyway, enough about weapons, the best use of this tech is to launch spacecraft, both from space and into space.

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The Carbon Devices inverse rail gun uses exactly the same linear motor principle of the conventional rail gun, with current passing along and between the rails via the ‘slug’, but effectively inverts the idea of a slug by using a continuous tape of engineered graphene, through which high current is passed to generate the pulling magnetic field. As each short segment of the tape is pulled forwards, the rest follows behind, and although the short segment being driven suffers high heating levels due to the high currents involved, new segments of tape are continuously pulled into play as heated segments exit. The tape as a whole will survive because only a small segment at any time is being subjected to high current, but of course the entire length of tape following is accelerated, along with the attached payload. The length of the tape and thus the exit speed achievable is only limited by practicality. The tape drive has a wide range of applications from ultra-high powered rail guns with exit energy hundreds of times that of current weapons, right up to a super-fast multi-motor space system that will one day deliver crew members or supplies such as water or materials to Mars bases in just 5 days, with a launch speed of 800km/s. Even that speed is limited mainly by the slow acceleration forces that humans can cope with. Another variant that fires inert payloads is an asteroid defense system and the achievable speeds for that could be far higher. This pic gives a crude idea of the concept, using many low powered ‘rail gun’ motors.

Slide34

This powerful propulsion system is scalable  (the system shown uses multiple motors and a very long string), and exit speed is only limited by the practical size and cost of the system. 800km/s is a sensible compromise size for routine space missions, since the size of the system scales with the square of the exit speed needed. Because of that, it can not be any practical use for interstellar missions, where technology such as light sails offer much greater suitability. Even if used in conjunction with a light sail, it could only knock a few weeks off a 100 year flight time. (For those of you with weapons interests, the Mars commute system carries about 360TJ, or 85 kilotons of TNT energy equivalent, well into nuclear territory. I haven’t bothered to calculate how powerful it would be if militarized instead of running at just 5g acceleration. ‘Very’ is a good enough guess.

In space, the tape will naturally start very cold which will be an advantage, and of course the tape can also be laid out in a long line to avoid assorted mechanical issues. All of that makes high speeds reasonably feasible. On the Earth however, it is very hard to arrange for a tape to be laid out in a long line, and spooling and indeed unspooling speeds present a huge mechanical engineering problem, not least of which is that a spool spinning at high rpm is dangerous in itself. Aerodynamic heating is also a huge issue for ultra-high speeds. Therefore, land-based variants need to be greatly scaled down. A number of people over the years have suggested using rail guns to launch things into space, and heating is always a severely limiting problem. The novel system we will announce isn’t a rail gun launch and neatly circumvents this problem.

Having said that, rail gun space launch is not impossible and we have devised two novel launch variants using the rail gun linear motor principle. Carbon Devices’ graphene foam invention in 2013 outlined a solid foam that could be made lighter than helium, that would be ideal for supporting loads in the high atmosphere. MIT have more recently produced a lightweight 3d-printed matrix that could be used to print larger shells containing only vacuum (and they could even be printed at high altitude to avoid collapse in the high pressure lower atmosphere).

Slide7If circuits for a linear motor are made from graphene and on a graphene substrate, all supported by such floating platforms, then a long, vertical, linear motor could be made and supported in the air that could accelerate a sled with a disposable heat shield front end, holding a rocket. Depending on acceleration tolerable, fairly high speeds can be obtained, and although not fast enough for orbit, would greatly reduce the size of rocket needed to achieve orbit.

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The first variant is entirely vertical. The rocket and crew or satellite payload would be attached to a sled, and the reusable sled would accelerate up the linear motor. With a few system engineering tweaks, it is feasible to make the path at least 35km high, with an exit speed of around 4000mph (1750m/s) for the 5g acceleration launch that is acceptable for astronauts. Although 4000mph is fast, it is no more than a useful starter push for a rocket that needs to reach the 17,500mph of the space station. Additionally, vertical speed is a useful boost, but no use in itself for orbit – a rocket travelling vertically would simply fall back to Earth eventually unless it gets high horizontal speed.

However, our second variant curves the track into a horizontal path at high altitude, again supported along its entire length by floating platforms made from carbon foam.

Slide39Assuming a 150km track, most of which is 35km high, we would have an expensive but reusable launch system that could accelerate humans up to 8600mph (3800m/s), about half way to orbital speed, and that would all be horizontal speed. It is easily possible to engineer the final sections of track to be higher in the atmosphere, and a slight incline would get our rocket out of atmosphere quickly to minimise heating issues, but the main benefit is that most of the high speed happens in the cold and thin high atmosphere. Such as system is feasible and would greatly reduce launch costs for human spacecraft. For a non-human payload, a 150km track can give full orbital speed for payloads that can tolerate in excess of 20g acceleration. Very many fall in that category, so this system could one day be used to achieve a fuel-free orbital launch.

As mentioned, these are only early system designs and forthcoming articles will outline more advanced Carbon Devices systems with greater potential to accelerate space development.

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Sky lines

High altitude solar array to power IT and propel planes

High altitude solar array to power IT and propel planes

Skylines are a zero carbon hypersonic air travel solution, a high altitude solar farm, a base for all sorts of high altitude electronics and even as a booster to reduce rocket engine size to get to orbit by getting spacecraft up to high hypersonic speeds before they need to fire engines. Well, most of the bits would be made of carbon materials, but it wouldn’t emit any CO2.

The pic says it all. A linear solar farm suspended in the high atmosphere (20km – 30km high) to provide an IT platform for sensors, comms and other functions often accomplished by low orbit satellite. It would float up there thanks to being fixed to a graphene foam base layer that can be made lighter than helium (my previous invention, see

https://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

which has since been prototyped and proven to be extremely resilient to high pressures too). Ideally, it would go all the way around the world, in various inclinations at different altitudes to provide routes to many places. More likely, it would connect a few major locations. Carbon materials are also incredibly strong so the line can be made as strong as can reasonably be required. Graphene is ideal for its weight, strength and most of all its electrical properties. It is perfect for making the various electrical circuits and as a base for solar panels.

This linear solar array would produce huge electric power, which is a potential use in itself, but housing various low ‘satellites’ would be even more useful, especially for comms where the latency would be lower than higher satellites and for surveillance where monitors will be closer to the ground.

As well as these, the flotation layer could also supports a hypersonic linear induction motor that could provide direct propulsion to a hypersonic glider or to electric props on a powered plane. Obviously this could also provide a means of making extremely low earth orbit satellites that continuously circumnavigate the ring. Once a plane is being pulled, it doesn’t need to breathe air for its engines, and with very thin air heating is less of an issue so it could go faster. High hypersonic speeds may be possible, making global air travel much faster and less environmentally damaging.

I know you’re asking already how the planes get up there. There are a few solutions.  Most likely they would use conventional engines to do so, and dock with a tether and sled once at a suitable height. Tethers could move to intercept, like a relay team’s members coordinating speed for handing over the baton, and a longer tether obviously means the plane doesn’t have to climb so high. Once it is tethered, of course it could climb a lot higher to escape air resistance, and some kinds of planes could even fly above the skyline, in very thin air, for super high speeds or even to assist in sub-orbital launches by reducing the needs for rockets. In theory, tethers could come all the way to ground level to airports, and electric engines powered by the skyline would then be used to get to height where the plane would pick up a sled-link, or else stronger links to the ground would allow planes to be pulled up by sleds, though these options would be far less feasible, because both mean that the air would have dangerous tethers dangling causing potential risks to other craft.

The power levels needed can be determined by looking at existing planes engines. The engines on a Boeing 777 generate about 8.25MW. A high altitude solar cell, above clouds could generate 300W per square metre. So a 777 equivalent plane needs 55km of panels if the line is just one metre wide. That means planes need to be at least that distance apart, but since that equates to around a minute, that is no barrier at all.

If you still doubt this, the Hyperloop was just a crazy idea when it was invented a century ago too. Now various companies are building demonstrators.

To finish on a tease, I mention above the potential for this to help spacecraft up to speed before they need to fire rocket engines. Although skylines are both feasible and useful for this, Carbon Devices is currently exploring some far superior ways of reaching space, but we are not ready to disclose them quite yet.

High Rise Rescue

A quick googling turned up this great idea, using an escape chute attached to the top of a fire crane. The chute has a fireproof external layer and people slow or speed their descent in it simply by varying their posture. Read the pdf for more details:

http://www.escapeconsult.biz/download.php?module=prod&id=26

The picture tells all you really need to know. You can see it reaches very high, up to 100m with the tallest fire appliance.

It is a great idea, but you can still see how it could be improved, and the manufacturer may well already have better versions on the way.

Firstly, the truck is already leaning, even though it has extendable feet to increase the effective base area. This affects all free-standing fire rescue cranes and ladders (suspension ladders, or ladders able to lean against a wall obviously include other forces). Physics dictates that the center of gravity, with the evacuees included, must remain above the base or it will start to topple. The higher it reaches and the further from the truck, the harder that becomes, and the fewer people can simultaneously use the escape chute. Clearly if it is go even higher, we need to find new ways of keeping the base and center of gravity aligned, or to prevent it toppling by leaning the ladder securely against a sound piece of wall that isn’t above a fire.

One solution is obvious. Usually with a high-rise fire, a number of fire appliances would be there. By linking several appliances to the ladder in a stable pattern, the base area then becomes far larger, the entire area enclosed by the combined appliances. At the very least, they can spread out across a street, and sometimes as in the Grenfell Tower fire, there is a lot of nearby space to spread over. With a number of fire appliances, the crane is also not limited to the carrying capacity of a single appliance.

If these are specialist hi-rise appliances, one or two would carry telescopic arms to support the rescue equipment, with one or more trucks using tension wires to increase the base area.

We also need to speed up entry to the chute and preferably make it accessible to more windows. The existing system has access via a small hole that might be slow to pass through, and challenging for larger people or those with less mobility. A funneled design would allow people to jump in from several windows or even drop from a floor above. Designing the access to prevent simultaneous arrivals at the chute is easy enough, even if several people jump in together

Also, it would be good if the chute could take evacuees away from the building and flames as fast as possible. Getting them to the ground is a lesser priority. Designing the funnel so it crosses several windows, with a steep slope away from the building (like an airplane escape slide) before it enters the downward chute would do that.

Another enhancement would be that instead of a broad funnel and single chute, a number of chutes could be suspended, with one for each window. Several people would be able to descend down different chutes at the same time. with a much broader base area, toppling risk would still be greatly reduced.

If a few support arms could be extended from the crane towards the building, that would provide extra stability until their strength (or building fabric) is compromised by fire. Further support might sometimes be available from window cleaning platform apparatus that could support the weight of the rescue chutes. If emergency escape chutes are built into the platforms could even make for an instant escape system before fire services arrive.

With these relatively straightforward enhancements, this evacuation system would be even better and would allow many people to escape who otherwise wouldn’t. OK, here’s a badly drawn pic:

All of this is possible with 2017 materials. As new carbon materials become economically available, it will be feasible to make the reach and size of this much greater and still stay within reasonable weight.

Carbon Devices (CD) is currently investigating mechanisms for rapid deployment of adaptive landing bags made from CD’s innovative graphene-based FG technology, that behave rather like smart air bags onto which people could safely jump, that could both actively intercept them if they don’t jump accurately, and give them a managed safe deceleration on landing.

Our FG is also the basis of rapid-deployment high towers also under investigation that could be used to get fire crews and equipment (or robotic equipment) to height to tackle fires. FG could greatly accelerate the processes of evacuation and getting fires under control.

FG will have a variety of other types of applications, since it can be used to make almost any volumetric or planar construction extremely rapidly, using enormous expansion capability coupled to high strength. In fact, in the above diagram, FG could provide the the tension members, compression members and support arms, as well as the escape chutes.

Carbon Devices Ltd has just been set up

Well, this all started with a frivolous idea a few years back when I invented a bunch of stuff for my sci-fi book Space Anchor. Recently, I have made a number of inventions (dozens in fact) that rely on graphene or carbon nanotubes or other carbon-based materials. Some are civil, many are weapons, and the company will own both sites, carbonweapons.com and this one, carbondevices.com.

I decided it is about time to set up a proper company rather than just a blog site. So I did, Carbon Devices Ltd.

It will own all the carbon-related intellectual property that I have invented over the last years. This site currently shows a few older ideas, as does the partner site carbonweapons.com, but all of the company’s recent intellectual property is as yet unpublished. Patenting or blogging ideas removes the bulk of their commercial value as inventions and publicity and ‘exposure’ is insufficient as a business model. Instead, short descriptors of ideas will sometimes be released that do not convey the important engineering details.

Some important ideas and concepts will however be fully disclosed for the public good, where the company does not intend to develop or sell them, but wants to make them publicly available to anyone free of charge and restriction and prevent others from seizing or controlling them. Such technical disclosures will be intended to disclose sufficient engineering detail to prevent others patenting them.

Some recent exciting and valuable space ideas will fall into that category. Watch this space!