electromagnetic launch with microwave propulsion

SpaceNut · 2020-03-16 16:53:13

There is a problem with a ship that has what much like a roads rumble strip where the speed of motion will change the sound pitch as the ship moves faster through the launch to boost. The same ripples will make a need for heat sheild alteration due to extra heating. Changing the spaces and hieghts of the ripple ridges will also alter the sound it makes as well as the pitch as the ship flies faster after launch as well.

Ships are smooth to keep the friction heating low as the rocket moves through the thick part of the air so as to not need a heat shield for launching through to the booster stage needs to ignite.

Taking an existing rocket may also prove hard to change for the lose of first stage mass that is part of the rockets center line balancing point. Removing that large mass means that we need to change how the shape of mass for the rocket gets distributed.

The first stage of that launch rocket is a glider even at high speeds and will need wings I believe to make it fly straight though it may be possible to use thrusters if fuel is there to place the angle of attack for the purpose of the climb from ground level to where we want to be for the stage ignition to finish getting the rocket to orbit.

kbd512 · 2020-03-16 17:45:49

tahanson43206,

Worrying about sonic booms is an utter waste of time. The short answer is that these birds are friggin loud and if you get a little too close they could actually kill you- in much the same way that putting your lawn chair right next to a launch pad is a really bad idea, as a certain dead Russian general officer discovered. However, this concept is about making omelettes and you're going to have to crack some eggs to do that. Locate the launch facility in the middle of nowhere. The US already has a hypersonic rocket sled at one of its test facilities in the desert and with or without noise complaints or dead jackrabbits, the facility continues to operate. To my knowledge, even that yahoo who volunteered for supersonic ejection seat tests lived through every crazy thing he tried to help improve ejection seat technology. NIMBYism will continue to exist for so long as someone is around to provide their opinion- everyone in existence thinks their little patch of dirt is the most precious thing in existence and no amount of public good or evidence to the contrary will ever sway their opinion.

The heat shield is an actual engineering problem, as is constructing the launch facility. You have to focus effort where you can actually accomplish something worthwhile. The "Come to Jesus" moment will occur the second Elon Musk realizes that even at the prices he thinks are affordable for the average person, nobody but multi-millionaires are capable of paying the asking price, whereupon it will be immediately obvious that there aren't any multi-millionaires outside of a handful of eccentrics who would sell everything they own and move to Mars to live like penniless old west settlers.

I could sell my house and cars and everything else I own and still not come close to paying for actually moving my family to Mars, which would be the only way I'd ever consider going. Furthermore, my wife and I are 40 years old now and it took that long to pay for the assets we hold now. The backbone of every country on this planet are all those working stiffs that make our world go round. None of them are moving at those prices because they could never afford to do it and the handful of rich people we have would never dream of getting their hands dirty cleaning their own toilets and growing their own food.

So, anyone who wants to can keep living in this alternate reality wherein some significant portion of the population from the industrialized world can afford to gas up several 747's... Or we can admit to reality and work on a solution that's somewhat less unaffordable, meaning approaching the realm wherein an upper middle class family consisting of people with the education (not so educated they no longer remember how to count) / experience (hopefully doing something that requires using their brain and their hands) / wealth (because you ain't going without quite a lot of it) to move to Mars has some chance of actually living there, albeit with significantly less material comfort, if that's what they decide they want to do.

I'd much rather figure out all the technical problems with the idea long before ever presenting it to anyone who might pay for some part of it. Making a little noise is not a bug, it's a feature. We're selling cheap launch services to people who can't afford more expensive launch services- a state of affairs that would apply to nearly every person going to Mars who's not named Elon Musk.

tahanson43206 · 2020-03-16 18:01:13

For SpaceNut re #76 and topic in general ...

To add a detail to the discussion of kbd512's concept of a launch from sea level ... if the trajectory is straight out over the Gulf of Mexico, and if the initial velocity is Mach 6 (6403 miles per hour according to Google), then the vehicle will reach an altitude of 20 miles after an elapsed time of 5 minutes and change.

Does this limited time for maximum heating have any effect on your vision of how this system would work?

The idea I was pursuing in recent posts is that appropriate design of the shape of the aircraft may (may) have an effect on the quality of the sound produced by the flight of the aircraft. The total amount of energy to be transferred to the atmosphere is probably predictable, and the question to be answered is whether that energy can be directed to reduce the impact upon living creatures along the flight path.

The reason I am pursuing this is that kbd512 has maintained his position in favor of trying to achieve the economic benefits that would (or could) flow from such a launch.

To get specifically to your point .... one would normally design an object to fly through the atmosphere at this velocity to try to minimize drag, and thus the energy that would be given up to the atmosphere.

It might be possible to alter the way in which sound is produced by the vehicle as it moves, but that effect might be achieved at the expense of increased drag, which would mean that more energy would have to be invested in the vehicle at the time of launch.

The question to be answered is whether a configuration of the vehicle shape to reduce the negative effects of disturbing the atmosphere is possible at all, and if it is, whether any beneficial effects might be sufficient to appease living creatures within hearing of the flight.

In my estimation, it will take an individual or a group with fairly advanced knowledge and computing ability to answer the question one way or another.

An extreme solution would be one in which the sound waves produced by the vehicle cancel each other out, much as dynamic headphones (are claimed to) achieve selective noise reduction by feeding an exact opposite waveform into an ear piece, so that the original noise disappears, and only the non-noise component of a sound pattern is heard.

Edit#1: Google: noise cancelling headphones

The resulting list for the search above is much richer with examples than I had imagined would be the case.

One thought that comes to mind is to issue a set of these headphones to every person within earshot of the flight.

Every living creature above and below the water would be impacted as well, but headphones for them seem unlikely.

(th)

Last edited by tahanson43206 (2020-03-16 18:05:59)

SpaceNut · 2020-03-16 18:32:51

GW can attest to this information on the SR72 use of composite materials such as carbon fiber reinforced carbon, previously used in missile nose cones and/or ceramic materials to withstand the high temperatures generated by air friction at the intended Mach 6 speed at 80,000 ft. and with that launch at sea level the speed makes a shield material even more of a required.

Heat damage will look like this x15 page https://theaviationist.com/2017/11/21/t … -7-flight/

Aerodynamic heating is the heating of a solid body produced by its high-speed passage through air (or by the passage of air past a test object in a wind tunnel), whereby its kinetic energy is converted to heat by adiabatic heating, and (less significantly) by skin friction on the surface of the object at a rate that depends on the viscosity and speed of the air.

All this tells me that we will need the standard rocket protection that we currently use for the payload fairings or payload shroud....

tahanson43206 · 2020-03-16 20:06:16

For SpaceNut re #79

Thank you for the link to the blog article about the X15, which included a number of photographs showing damage suffered by the vehicle, and commentary by the pilot. It is not surprising the plane was immediately retired and put on display.

Until advised otherwise, i'm assuming kbd512 is determined to pursue the idea of launch at Mach 6.

Your reminder of the effects of heating is helpful. If the vehicle were launched at ground level, even more heating protection would be required than was the case at 80,000 feet, as you point out.

However, I still think the problem of the sound produced by the launch is the first hurdle to be overcome. it's good to know about other hurdles, but unless that one is solved to the satisfaction of every US citizen within earshot of the launch site, none of the other hurdles will get a chance to receive attention.

It seems likely this forum does not presently include a person with the knowledge and experience, and (potentially) the computational resources to address the sound mitigation problem.

There would appear to be no other option than to invite all current members, or anyone who reads the forum, to think about who they might know who would be able and potentially willing to take a look at the problem.

It seems highly unlikely the problem CAN be solved easily, because surely it would have been solved long ago if it had been easy. The economic incentives have been present for a long time. Never-the-less, solving the problem is absolutely necessary in order for kbd512's vision to advance to the next hurdle, whatever that may be.

As a side note ... solving the problem for kdb512's vision would ALSO provide economic advantage to whichever organization is first to exploit if for civilian air travel.

(th)

Last edited by tahanson43206 (2020-03-16 20:07:26)

SpaceNut · 2020-03-16 20:40:59

What you are still working on is fluid motion with air being the fluid. What nasa does for its rocket shapes and designs is use the wind tunnels to solve for the shape of the flow of air around the rocket as it moves. Sure the rockets are precision scale models for this testing but it does get you the data that we need.

The question of the initial launch speed is just not going to change all that much at the lower mach 1 speed as thats what the carrier plane was doing when the Pegasus was released. So do we need to get all the way to mach 6 is the question. The shuttle went through the atmosphere at one point slowing down to mach 5 or max q as they indicated in the launch profile.

While a mach 1 would lower cost a little its not until you start to remove mass, engines and fuel will the next be jump occur. So the question is for a near clean design to come for the rocket is at what speed of capable launch can we achieve for the new mass number for the rockets design can we actually do.

The second part of the design is the carrier platform as its not going to stop at the end as that takes momentum away from the rocket that is resting on it somewhat anchored or tied in place for the launch. The over ocean launch solution I gave earlier so the rockets mass will need that mass calculated into rockets performance to get the new numbers for launching the payload to orbit.

SpaceNut · 2020-03-16 21:38:53

https://www.nasa.gov/connect/chat/sonic_boom_chat.html

https://www.space.com/25629-nasa-supers … -tech.html

https://opentextbc.ca/physicstestbook2/ … nic-booms/

https://fyfluiddynamics.com/tagged/supersonic/

https://ntrs.nasa.gov/archive/nasa/casi … 165091.pdf

https://ntrs.nasa.gov/archive/nasa/casi … 008141.pdf

https://en.wikipedia.org/wiki/Supersonic_speed

SpaceNut · 2020-03-16 21:58:34

The Tsiolkovsky rocket equation, classical rocket equation, or ideal rocket equation is a mathematical equation that describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself using thrust by expelling part of its mass with high velocity can thereby move due to the conservation of momentum. Momentum is defined to be the mass of an object multiplied by the velocity of the object.

https://www.real-world-physics-problems … ysics.html

https://www.apogeerockets.com/education … ter320.pdf

tahanson43206 · 2020-03-16 22:07:24

For SpaceNut re #82

Thank you for the impressive list of links ... The chat contained promising hints.

More About Ed Haering
Ed is an aerospace engineer at NASA's Dryden Flight Research Center in Edwards, Ca. He really likes the variety of his work, which can involve starting up a new research program, doing computer simulations and analysis, troubleshooting instrumentation on exotic aircraft, and conducting field measurements in remote locations.

From LinkedIn:
Experience
NASA Armstrong Flight Research Center
Aerospace Engineer
NASA Armstrong Flight Research Center
Jan 1984 – Present36 years 3 months
Technical lead for supersonic aerodynamic research; from concept formulation, experiment design, prediction, execution of flight and field measurements, analysis and reporting, specializing in innovative techniques.
National Aeronautics and Space Administration (NASA)
Aerospace Engineer
National Aeronautics and Space Administration (NASA)
1984 – Present36 years
Education
University of Illinois at Urbana-Champaign
Bachelor of Science (B.S.)Aerospace, Aeronautical and Astronautical Engineering
1982 – 1987
University of Southern California
Master of Science (M.S.)Aerospace, Aeronautical and Astronautical Engineering

This is the kind of person who might be able to help to retire the risk of excessive noise from a vehicle launched at Mach 6 at ground level.

One idea that I picked up from the chat is that a small cross section of the vehicle might help.

A telephone pole shape would have a small cross section as compared to the overall volume of payload, and the tip could be fitted with an ablative nose cone for the trip through the lower atmosphere.

The telephone pole shape would also have the advantage of suitability for on-orbit construction such as of the "girder" for artificial gravity.

(th)

tahanson43206 · 2020-03-17 08:02:31

This is for kbd512 .... I went back and looked at the first post in this topic. The content is mostly a reply to Louis, which helps to put the beginning of this topic in historical context, but leaves a first time reader without much of a sense of what you've guided the topic to become over time.

Please consider going back to the first post, and edit it to show a summary of the goals you would like to achieve with this topic.

Please do NOT add any unnecessary detail, as you have the capacity to do. Instead, you could (if you have time and are willing) create an index to the prodigious posts full of detail that you have added to the topic over recent weeks.

***
I'm now touching base to see if the current vision I am holding is reasonably close to what you've been wanting:

1) Land based launch facility fixed in place to send a package of cargo, electronics and supplementary solid rocket out over water
2) Mach 6 as a nominal launch velocity, with even greater velocity desirable if it can be achieved
3) A very small cross section to minimize sound production (this is derived from NASA interview posted by SpaceNut)
4) A very long thin probe at the tip to help to minimize sound production (this taken from NASA interview posted by SpaceNut)
5) EML technology based upon the US carrier example "Gerald R. Ford" and extended as needed to 1 km or more
6) A straight flight from Earth to 20 miles altitude over a run of 400 miles in 5 minutes of flight time
7) Ablative tip material to survive the flight through the lower atmosphere
8) Design of the vehicle body to be used as a structural element in a large space vehicle (per elderflower inquiry)
9) One metric ton of payload delivered to LEO (total vehicle mass will include structure, rounding rocket and electronics)

More elements can and should be added. Are these in the ballpark of what you'd like to see coming out of this topic?

(th)

Last edited by tahanson43206 (2020-03-17 14:51:50)

SpaceNut · 2020-03-17 16:54:50

The diameter of the rockets body is more about tank size to length with the payload not being the only factor for the overall diameter needed as the payload shroud or fairing can be much larger than the body diameter.

The next factor is the reuseablity factor as to how much and what portions can be reused as its got factors that not only impact the design but how we get the parts back as well.

While the payload shroud is the main part that helps with the payload we lift the actual payload itself is what changes the adaptor part of that fairing and could change the overall rocket stages size, mass and shape of them to accomidate the task of launch the payload to orbit.

I would think that water would be mostly likely number 1 for the most wanted item to get to orbit. With number 2 being food and some equipment types. That could be followed up with buffer gasses as number 3.

We need to take the atitude that what goes up is never coming back down as trash and its to be reused once empty.

tahanson43206 · 2020-03-17 18:50:56

For SpaceNut re #86

Hopefully kbd512 will return to clarify what he has in mind for this topic.

Your post implies that the vehicle would be returned to Earth after delivery of cargo to low Earth orbit.

In recent posts, I have proposed that the vehicle body be designed to stay in LEO for use as a structural element for space vehicles.

A long tubular structure would have potential for strength in a large structure.

There would be no need for fairings in a vehicle of this kind.

The body of the vehicle would hold the payload until it is transferred to the customer facility. After that, it would become (if properly designed) a construction component.

I agree that water would appear to be an attractive payload, for the right customer. it would have the distinct advantage of ease of packaging and ease of handling, both on Earth and in orbit.

(th)

kbd512 · 2020-03-17 21:55:18

tahanson43206,

I'm still gathering my thoughts on this, but I'll respond after I've had a chance to mull over some more design decisions. Maybe a small booster stage with a solid fuel ramjet that's parachute recoverable wouldn't be the worst thing in the world, but I still think we'll need to get that initial starting velocity near or even past Mach 1. At the very least, it's going supersonic when it leaves the launch rail. The ramjet stage could provide an effective specific impulse as high as 1,200 seconds or so. Provided we could accelerate from Mach 1 to Mach 6 on ramjet power, even though the propellant requirement reduction is not as extreme as with a hypersonic launch, it would greatly ameliorate the aerodynamic heating and noise issues. Accelerating a fighter jet sized vehicle to Mach 1.2 at sea level won't kill anyone, or I'd already be dead.

tahanson43206 · 2020-03-17 22:20:52

For kbd512 re #88

It is good to see your flexibility as you approach the challenges of trying to move from vision to modeling a possible real-world implementation.

Your change of approach, from Mach 6 to Mach 1 would appear (at first glance) to improve chances of being able to offer passenger service in addition to the all important freight service.

I am continuing to pursue the question of optimum design for a Mach 6 vehicle because there seems to be a small chance the concept could actually work, were you to decide to return to that idea. I am in the process of drafting a letter to Ed Haering, whose chat session with students SpaceNut showed us a few posts back. While Mr. Haering will surely NOT have time to address the question of feasibility of a Mach 6 telephone pole space vehicle, I am hoping he will have an acquaintance who would be interested in considering the issues involved.

As a reminder (mostly for readers of the forum, since I'm confident you already know this) NASA and others have carried out detailed studies of electromagnetic launch, but since nothing ever came of those studies, I think that your approach, of building upon the success of the Gerald R. Ford catapult design makes a lot of sense. What ** I ** do not know, at this point, is whether there may turn out to be some practical reason why the catapult cannot be extended to launch at velocities greater than 150 miles per hour. It would be helpful to bring a designer of that system into the conversation, if that is possible.

Edit#1: The catapult technology is not the only one being developed by the US Navy:

The Navy's Railgun Is About to Get Faster and More Powerful
www.popularmechanics.com › military › research › news › us-navy-r...
Jul 24, 2017 - The railgun works by using extremely high electrical currents to generate magnetic fields capable of accelerating a projectile to speeds of up to Mach 6, more than twice as fast as existing projectiles. The railgun has a range of more than 100 miles.

The projectile the US Navy is working with is intended for interaction with the assets of an opponent.

The projectile we are discussing here would be somewhat more massive, and it would be intended for delivery of freight to low earth orbit.

I note that (it appears) the systems already tested can reach Mach 6. However, the range of 100 miles is significantly less than is needed for a space launch.

The problem to be solved is (relatively) simple ballistics. There is a velocity at which a projectile launched from Earth will reach orbit. Mach 6 is not that velocity. So now I come back to the telephone pole design for a space freight vehicle. If the sound management problem can be solved for such a vehicle travelling at Mach 6, then there is a possibility those solutions would work for higher Mach numbers. It should be noted that there are laws of physics that govern the processes at work here, so it may turn out that sound mitigation procedures may not overcome the sheer magnitude of the energy that would be dumped into the atmosphere by a vehicle operating at a velocity sufficient to take it to low Earth orbit.

On the OTHER hand, unlike with the case of gas propulsion, which is limited (apparently) by the speed of sound in Hydrogen, at this point, I am blissfully unaware of any limitations imposed by physics which would preclude acceleration of a vehicle to LEO speeds using electromagnetic acceleration.

In short, because of our collective ignorance, we have a window of opportunity to explore this topic before the inevitable real world facts impose themselves.

(th)

Last edited by tahanson43206 (2020-03-18 08:36:32)

SpaceNut · 2020-03-18 17:06:33

The fairing or payload shroud protects the cargo within it and it has the heatshielding needed to go through the atmosphere on its way up as its coated with a material that contains the pica material. If not reusing payload enclosure then we must change the rockets payload to have stabilization thursters and fuel to be able to dock the item with the target unloading unit. That means the payload shroud or fairing is ejected since that would cover the entrance for docking under the top of it unless we design the tip to hinge open as the Dragon does. The Dragon does not have docking capability and must use the robotic arm to make that docking happen. The cargo opening once docked would be how the merchandise is retrieved from the inside of it.

tahanson43206 · 2020-03-18 17:40:27

For SpaceNut re #90

Thank you for continuing to think about this topic, and the various alternatives which have surfaced over the past 80+ posts.

Your suggestion of the tip swinging back for docking with a customer site in orbit seems most applicable for the telephone pole cargo vehicle.

Another variation of that idea is to screw the cap on before launch, and unscrew the cap after the vehicle arrives at the customer site. In that sense, the caps would be similar to fairings, in that they would be recoverable. Collections of them could be returned to Earth in a much larger vehicle. They could be refitted with ablative material and reused. These devices could be fitted with navigation electronics, so that the cargo containers themselves could be designed for on-orbit construction of large structures.

(th)

It seems to me that the less hardware that is needed on the cargo vessel to help with docking the better. The customer site can be fitted with arms and small robot vessels to go out to retrieve cargo shipments.

kbd512 · 2020-03-18 18:01:16

tahanson43206,

It's mostly a matter of money and politics. A high subsonic or low supersonic speed electromagnetic launch has been feasible since at least the implementation of the commercial MAGLEV trains in the 1980's. The L0 series Shinkansen hit 375mph in 2015 and is operating with passengers, albeit still in testing so far as I know. L0 is many times the mass of the proposed fighter jet / booster combination.

A launch facility would have a cost ranging into the low billions and has to be built near an ocean. Unfortunately, it's not a particularly juicy piece of pork that can be sliced and diced six ways to Sunday to farm out porklets across America to secure votes in other Congressional districts.

Prime real estate is our coastlines, but that's about it. I was actually thinking about Puerto Rico. They need a "draw", if you will, to promote STEM there to help reduce the systemic poverty. It's a "government project", so someone can make a buck off of building it. We need to give them something and a commercial space launch port is a good piece of infrastructure to have. We already have Starship space launch ports in Texas. Beyond that, we can use their port to deliver the cargo and desalinate the sea water for potable water and propellant. I would like to see our textiles and pharmaceuticals manufacturing moved back to Puerto Rico from China as well. COVID-19 is proving just how unreliable dependence on foreign economies can be.

As to the physics of the problem, the rate of acceleration in the lower atmosphere determines the severity of the aerodynamic heating because as soon as the vehicle leaves the track it pitches up to clear the dense lower atmosphere. A high acceleration rate, which would work for most cargo but not humans, would help ameliorate that problem.

Have a quick read about the gun-launched solid-rocket propelled projectiles from Project HARP:

Project HARP - Martlet 4

Edit:

Wikipedia - Project HARP

Take note the 6,750fps / Mach 6 muzzle velocity of the last projectile launched.

Last edited by kbd512 (2020-03-18 18:16:03)

SpaceNut · 2020-03-18 19:16:17

The total length and diameter is a function of the fuel mass required for the design and since its not just a single stage is going to have a shape that is not a cylinder from engine to nose....

https://historicspacecraft.com/Rockets_Orbital.html

Here is the Minotaur V rocket, take a notice to the top double angle area as thats the payload protection shrould or fairing as it might be called. https://en.wikipedia.org/wiki/Minotaur_(rocket) family or series with different sizes of stages for payload capability.

https://en.wikipedia.org/wiki/Minotaur_V

https://www.nasa.gov/pdf/433343main_Minotaur_V_fact.pdf
the cutaway of the payload shroud in on the second page.

The ﬁrst three stages of the Minotaur V are former Peacekeeper solid rocket motors with over 50 ﬂights of each stage. The fourth and ﬁfth stages are commercial motors that can be selected to provide varying levels of performance. The stage four motor is a Star 48V conﬁguration.
The rocket stands 80 feet (24 meters) tall and is about 7.6 feet (2.3 m) wide. When fully fueled, it weighs 197,034 pounds (89,373 kilograms).
The Minotaur rocket can launch payloads of up to 1,400 pounds (630 kg) into geosynchronous orbit and payloads of up to 750 pounds (340 kg) towards the moon.

https://www.nasaspaceflight.com/2017/08 … -5-launch/

The first stage burned for fifty-six seconds before separating. The second stage – an SR-119 – ignited and burned for fifty-seven seconds, separating about eleven seconds after burnout. The third stage, an SR-120, ignited at staging to begin its seventy-three second burn. Nineteen seconds after the third stage ignites, with the rocket at an altitude of 130 kilometers (81 miles, 71 nautical miles), Minotaur’s payload fairing separated from the nose of the rocket.
After third stage burnout, the launch entered a coast phase as the vehicle ascends towards the apogee, or highest point, of its trajectory. Ten minutes and twenty-seven seconds into the coast, the spent third stage was jettisoned, with the fourth stage igniting eleven seconds later at thirteen minutes, 55 seconds mission elapsed time. The Orion-38 fourth stage burned for a minute and seven seconds, injecting ORS-5 into an initial parking orbit.

The goal in design is to replace the first few stages with the catapult launch and still achieve orbit. The catapult needs to be able to launch the remaining portion of the rocket to speed for the next stage to fire when its needed to finish the launch to orbit sequence.

tahanson43206 · 2020-03-18 19:38:24

For SpaceNut re #93

Thank you for this impressive (to me for sure) collection of Minotaur images and text!

From a US taxpayer perspective, this is a very GOOD use of some of our vast array of military hardware.

For kbd512 re #92

Puerto Rico is an interesting suggestion. The smaller islands to the East would be impacted by overflights.

Attention paid to noise mitigation might help to ease concerns folks might have.

In addition, a decision to stay just below or just above Mach 1 might help considerably with design for human passenger launch, although that market seems to be shaping up as highly competitive with multiple players and multiple approaches.

As you are aware, launching at an angle would be advantageous, and Dr. Hunter was planning to launch from a floating facility in the ocean.

I took a quick look at the topography of the ocean around Puerto Rico, and found that one of the deepest trenches in the oceans of Earth is ** right there **, West of Puerto Rico.

A tube of reinforced concrete could be lowered down the West side of the island, to provide a weather proof launch platform of whatever length turns out to be most cost effective. As you have pointed out, the infrastructure that would be required to support an EML on this scale would surely contribute to a recovery of the economy, and perhaps to achieving new heights.

The tube would be fixed in position, but in recent posts you have already indicated a willingness to plan for trajectory adjustment as the vehicle ascends. The orientation (azimuth and angle of elevation) of the tube could be chosen for the optimum value to future customers. A consideration is that Elon could fly to meet cargo to be delivered by the launcher from his location to the West. The orbital plane of the EML would then become a standard meeting place for expeditions planning to refuel and resupply before departure from LEO.

One caution I would offer is that it is NOT (in my opinion) reasonable to conclude that because engineers have achieved run speeds of 350 miles per hour for a train, they can be expected to write a plan to achieve greater speeds for a space vehicle. There would appear to be reason to hope higher speeds might be possible, but in the absence of knowledgeable commentary by an engineer who is working in the field, I would recommend caution about making assumptions.

On the other hand, US Navy success with rail guns seems to indicate that the technology used for that application ** can ** achieve higher velocities.

It would be interesting to know what rail gun engineers could do with an ocean mounted tube. Perhaps the answer for economic competitive launches of cargo is to drop individual shipments down to whatever size the US Navy is using for their payloads, and just fire with sufficient force to reach LEO. The vehicles will still require an orbit smoothing rocket as Dr. Hunter had planned, but his design anticipated the ability to withstand the G loads of the hydrogen launcher, so I expect the same technology would work fine for an EML.

On the whole, my sense is that the three active contributors to this topic are making some progress.

As a reminder, contributions by others might help to move things along even more rapidly.

(th)

Last edited by tahanson43206 (2020-03-18 19:50:43)

tahanson43206 · 2020-03-19 08:35:49

This is for both SpaceNut (Administrator) and kbd512 (topic manager)

I'd like to suggest new topics affiliated with this one, dedicated to three candidate geographical locations.

The first is Puerto Rico, as suggested by kbd512
The second is Southern Texas/Northeastern Mexico, which I see as potentially advantageous for a variety of reasons
The third is Indonesia, which recently announced the beginning of a five year ambition to launch a rocket to LEO

All three have the needed feature of a large open ocean space to the East, but each have populations who would be concerned about what an EML site would mean for them, and who would be impacted positively and negatively to varying degrees if an EML is actually built.

I see two directions that the initiative is heading. The first would appear to be headed toward delivery of cargo to low Earth orbit, in which case high G forces and high velocity would combine to permit minimal cost. The second would appear to be gentler boost of passenger carrying vehicles which would benefit from acceleration to Mach 1 or thereabouts, at which point a combination of aircraft propulsion and rocket propulsion would complete delivery.

Proposed titles for the new topics would be:

EML Puerto Rico
EML Texas
EML Mexico
EML Indonesia

I would like to suggest splitting Texas and Mexico because of the different political systems at work. However, the technical aspects of projects in both locations would (presumably) be identical.

(th)

Last edited by tahanson43206 (2020-03-19 08:36:55)

SpaceNut · 2020-03-19 10:09:36

I think that we can do that a bit later as we are still working on the eml launch details of power and mass of the rocket systems needed to be able to perform the act of getting payloads to orbit for less.

The catapult and such style eml are from the air craft cariers and here are the links for the class sizes that we are trying to leverage a system from. From this we get the aircraft mass, runway distance and other details to use in calculating where we need to be to perform the launch task.

https://en.wikipedia.org/wiki/Queen_Eli … ft_carrier
https://en.wikipedia.org/wiki/Essex-cla … ft_carrier
https://en.wikipedia.org/wiki/Nimitz-cl … ft_carrier

Now time to go read about these systems....The aircraft masses that are being accelerated and energy levels.

edit
https://science.howstuffworks.com/aircraft-carrier3.htm

Each catapult consists of two pistons that sit inside two parallel cylinders, each about as long as a football field, positioned under the deck. The pistons each have a metal lug on their tip, which protrudes through a narrow gap along the top of each cylinder. The two lugs extend through rubber flanges, which seal the cylinders, and through a gap in the flight deck, where they attach to a small shuttle.
When the plane is ready to go, the catapult officer opens valves to fill the catapult cylinders with high-pressure steam from the ship's reactors. This steam provides the necessary force to propel the pistons at high speed, slinging the plane forward to generate the necessary lift for takeoff. When the cylinders are charged to the appropriate pressure level, the pilot blasts the plane's engines.
This totally steam-driven system can rocket a 45,000-pound plane from 0 to 165 miles per hour (a 20,000-kg plane from 0 to 266 kph) in two seconds!

This is the Nimitz class and it stretches 1,092 feet (333 meters) from bow to stern.

The flight deck only has about 500 feet (~150 meters) of runway space for landing planes.

tahanson43206 · 2020-03-19 11:46:49

For SpaceNut re #96 and topic in general.

Thanks for thinking about the split suggestion.

As a suggestion, if you can find information on design of the Gerald R. Ford electromagnetic launch system, it would be of particular interest for those who are (hopefully) following this topic. kbd512 has contributed the important insight that energy is (I gather) stored in large ? rotating masses, which are able to dump large amounts of energy into magnet coils in a short amount of time as the vehicle to be accelerated approaches each magnet station.

While steam catapult history will surely be interesting in a number of ways, the more modern electric catapult design will be of interest as well.

Engineering issues to be discovered would include how the existing carrier system measures the approach of the launch sled, and how the electronics times discharge of the rotating masses to insure maximum effectiveness of the pulling power exerted by each magnet.

The work of Dr. O'Neill is available for study from ssi.org (Space Studies Institute). I'm pretty sure you will discover that the launcher design pioneered by Dr. O'Neill and his graduate students used radio frequency generated wave forms as a way to coordinate expression of energy as the payload device passed each magnet station. The magnet stations were spaced out (as I recall) to insure that the payload device was arriving at station just as the energy peaked in value.

This is the level of engineering detail I am hoping to see recorded in the forum. There needs to be a way to collect such detail in meaningful, easy to find categories. The present system of totally random deposits of useful information is entertaining, for sure, but it seems to me there might be a better way to organize the archive for serious students.

Edit#1: For kbd512

An idea I have not seen proposed anywhere else (so far) is a hybrid design. Dr. John Hunter carried design of a hydrogen gas launcher about as far as it can go, from everything I've been able to learn from published reports. The US Navy has demonstrated both heavy object acceleration (carrier catapult) and middle mass acceleration to high velocity (rail guns).

It might be possible to combine the two technologies. A hydrogen gas impulse could provide a substantial momentum to a vehicle whose subsequent progress would be accelerated by magnetic force. Another benefit of a hybrid design is that drag can be overcome in the vicinity of a moving vehicle, if there is an abundance of gas coming along behind to push air molecules ahead of the nose until it reaches the end of the run. This concept presumes an enclosed acceleration facility, such as the tube described in a recent earlier post.

(th)

Last edited by tahanson43206 (2020-03-19 14:25:38)

SpaceNut · 2020-03-19 14:48:31

post #93 & 96

Minotaur V rocket: The rocket stands 80 feet (24 meters) tall and is about 7.6 feet (2.3 m) wide. When fully fueled, it weighs 197,034 pounds (89,373 kilograms).
launching plane: This totally steam-driven system can rocket a 45,000-pound plane from 0 to 165 miles per hour (a 20,000-kg plane from 0 to 266 kph) in two seconds!

Using exisiting launch forces and rocket we can see that we can not even move the rocket off from the deck of the nimitz as it would require all 4 catapults to even get the rocket moving very slowly. That said now to begin researching mass for the eml as that means we need to design a very light mass rocket to make use of a system that is intended to save money per launch. Will need to look back at other rockets to see if there are any that exists that would fit the model of launch system used to reduce rocket size.

SpaceNut · 2020-03-19 16:12:50

https://en.wikipedia.org/wiki/Gerald_R. … ft_carrier

https://en.wikipedia.org/wiki/Electroma … nch_System

The EMALS' 300-foot (91 m) linear induction motor or LIM will accelerate a 100,000-pound (45,000 kg) aircraft to 130 kn (240 km/h; 150 mph).

Still falls short for the rocket and would require 2 units to get the small rockets we have moving...

The EMALS energy-storage system design accommodates this by drawing power from the ship during its 45-second recharge period and storing the energy kinetically using the rotors of four disk alternators; the system then releases that energy (up to 484 MJ) in 2–3 seconds. Each rotor delivers up to 121 MJ (34 kWh) (approximately one gasoline gallon equivalent) and can be recharged within 45 seconds of a launch; this is faster than steam catapults. A maximum-performance launch using 121 MJ of energy from each disk alternator slows the rotors from 6400 rpm to 5205 rpm.

https://en.wikipedia.org/wiki/Linear_induction_motor

https://en.wikipedia.org/wiki/Coilgun

https://en.wikipedia.org/wiki/Mass_driver

tahanson43206 · 2020-03-19 17:36:04

For SpaceNut re #99 .... Thanks for these on point links. There is a lot to study so will comment later.

Something for you to think about is that the distance limitations of an aircraft carrier do not apply in this situation.

A launch run of a kilometer is routinely discussed. The questions ** I ** have are about whether the technique that works for an aircraft carrier can be extended over longer distances and at greater velocities. It would help a ** lot ** if an electrical engineer with experience in building the aircraft launcher were to join the discussion. I think the sonic boom problem is addressable by changing the shape of the vehicle and reducing the cross section to telephone pole size. Confirmation by an engineer trained in ** that ** specialty is (obviously) still pending.

(th)

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