electromagnetic launch with microwave propulsion

SpaceNut · 2020-03-24 08:14:27

Another term is stepper motor, permanent magnet motor, BCDL these are controlled by pulsing the coil to cause the rotor to turn.
The contacts that pass the current to high power will burn and need to be replaced as the pulses are conducted into the coils.
The rail needs to have either coils along its length or a car for the motor to make the moving action with as the rockets not sliding on its sides up the ramp. Are we pushing or pulling in the design of the rail.

tahanson43206 · 2020-03-24 08:24:18

For kbd512 re topic ...

Your reply to quaoar in another topic contained a section on shielding.

http://newmars.com/forums/viewtopic.php … 76#p166576

What I have in mind for the tip of a telephone pole cargo carrier is a shaped section that can survive flight at escape velocity through the lower atmosphere.

From Google:

The escape velocity from Earth's surface is about 11.186 km/s (6.951 mi/s; 40,270 km/h; 36,700 ft/s; 25,020 mph; 21,744 kn).
Escape velocity - Wikipedia

The pertinent figure from the quote is 7 miles per second.

The article at the link below provides generally accepted altitudes for generally accepted layers of the atmosphere.
https://www.space.com/17683-earth-atmosphere.html

Taking the contents of the article as valid for the present post, half the Earth's atmosphere lies below 12 miles (20 km). Assuming a launch angle of 45 degrees, a cargo vehicle travelling at 7 mps would traverse the hypotenuse of the right triangle with side A set to 12 miles in 17/7 or 2.4 seconds or so.

The velocity of the vehicle would be reduced by some amount, but the atmosphere above the Troposphere will be decreasing in density rapidly.

After a full 10 seconds the vehicle would have reached an altitude of 48 miles (77+ km), well into the Mesosphere.

Vehicles accelerated to dock with customer facilities in LEO or GEO would spend more time in the atmosphere

Taking 160 km as the lowest practical altitude for an Earth orbit, the flight path would be a ballistic arc which peaks at 160 km.

Quote from Google:

Definition: Technically, objects in low-Earth orbit are at an altitude of between 160 to 2,000 km (99 to 1200 mi) above the Earth's surface. Any object below this altitude will being to suffer from orbital decay and will rapidly descend into the atmosphere, either burning up or crashing on the surface.Jan 6, 2017

I'll have to look for a calculator for this situation. A quick check with Google revealed a nice assortment of ballistics sites for small arms users.

(th)

tahanson43206 · 2020-03-24 08:31:03

For SpaceNut re #127

SpaceNut wrote:

Another term is stepper motor, permanent magnet motor, BCDL these are controlled by pulsing the coil to cause the rotor to turn.
The contacts that pass the current to high power will burn and need to be replaced as the pulses are conducted into the coils.
The rail needs to have either coils along its length or a car for the motor to make the moving action with as the rockets not sliding on its sides up the ramp. Are we pushing or pulling in the design of the rail.

Thanks for helpful design issues to address.

Can you describe the contacts a bit more? We have three people trying to visualize this system, and each has a different mental model.

The point of reference is whatever is being done on the Gerald R. Ford. Anything else is speculation.

I posted a link to a patent for electromagnetic launcher in a post earlier in this topic, but have not studied it to see if it has any bearing on the Ford implementation.

Ideally, this topic would attract an electrical engineer with actual experience building the Ford EML.

A person with that background and with the ability to share non-classified details with the public would be a valuable addition to this investigation.

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Last edited by tahanson43206 (2020-03-24 08:31:42)

SpaceNut · 2020-03-24 08:34:48

If I recall the shuttle made orbit in about 10 minutes after launch as its not a straight line but follows multiple arcs along the way towards orbit.

tahanson43206 · 2020-03-29 16:17:15

2020/03/29 for kbd512 ELM topic ...

The purpose of this investigation is to follow up on a recommendation of kbd512 to consider monopropellant for the cargo vehicle proposed for an ElectroMagnetic Launch system.

To recap: The proposed system would consist of a cylinder 30 centimeters in diameter …
1) Total mass 3 Metric tons
2) Total length …. whatever comes out of the trades
3) Payload delivered at LEO to customer facility: 1 Metric ton
4) Balance of mass includes:
a) Structure
b) Nose cap with navigation equipment and battery
c) Rocket for orbit circularization and docking with customer facility
d) Rocket fuel
e) Whatever else is needed
5) The vehicle would be designed for use in construction after the primary mission is completed.

The original concept for orbit circularization (from Dr. John Hunter ‘s writings) was a solid fuel rocket.

A solid fuel rocket might be expected to survive high-G acceleration, but once ignited, it would burn until fuel is exhausted, or the burn is snuffed by the navigation system.’

A mono-propellant system would be restartable, and therefore is a better choice for this application, if it can be proven to work after high-G acceleration.

A Google Search for Monopropellant rocket engine yielded:

About 73,800 results (0.66 seconds)

A design consideration is safety of the propellant for ground personnel, as well as for astronauts working with the expended vehicle after payload delivery. It is anticipated that the vehicles will be designed to serve as integral components of large on-orbit space going structures after payload, navigation equipment and any other components to be returned to Earth for re-use are recovered.

This study will include consideration of bi-propellant systems, as they become available, and as they are shown to demonstrate increased safety to personnel on Earth and on orbit.

https://www.intechopen.com/books/aerosp … et-systems

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tahanson43206 · 2020-03-29 20:00:23

Continuing from #130 ...

This quote is from the chapter of the book at the link in #130 ...

For hypergolically activated bipropellants, a system development has been presented that uses, instead of the risky MMH and N2O4, a kerosene-based fuel and hydrogen peroxide oxidizer. Both are nontoxic and in common inexpensive usage in daily life.

For kbd512 ... taking the second alternative for discussion ...

Does it seem feasible to you to include a "kerosene-based-fuel" and hydrogen peroxide in a vehicle subject to high-G forces?

They would exert lateral force on the cylindrical wall of their containers. Is there a material that could withstand those forces?

If this topic does not include a post which gives G forces for various launch scenarios, then one should be added.

I don't remember such a post, but might have missed it.

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SpaceNut · 2020-03-29 20:30:32

What makes any fuels safe for use under the stress of launch is just the science of materials and thickness for the tanks plus side walls of the rocket that is being moved. Adding mass in excess of what is testable for what is required would mean a lose of payload capacity for the mission of getting a useable size or quantity of mass to orbit is critical.
This is one of the reasons for testing of what is made to prove out what level of pressure that the design can take.

kbd512 · 2020-03-29 20:47:57

tahanson43206,

High test / high purity H2O2 is very unstable. A very high test (95%+) H2O2 would be use or lose within a day or two. It's frequently talked about as a LOX alternative, but the problems associated with storing it are worse than the benefits of having a non-cryogenic oxidizer. H2O2's bulk density is slightly less than the bulk density of LOX, so the best you could hope to get from a very high purity product would be a non-cryogenic oxidizer with worse specific impulse performance and a very slight bulk density improvement for the entire propellant system, presuming H2O2/RP-1 vs LOX/RP-1. The bulk density improvement is attributable to the mixture ratio difference between H2O2 and LOX. The lower specific impulse for H2O2/RP-1, about 50 seconds IIRC, makes it a non-starter in my book. Isp is no better than a solid rocket and the solid rocket would have considerably improved bulk density. H2O2 is also considerably more expensive than LOX to boot.

tahanson43206 · 2020-03-29 21:24:31

For kbd512 ... re #133 ... thanks for your reply! I'm sure glad you know more about these chemicals than I do !!!

I'll keep looking at monopropellants, unless a bi-propellant combination looks as though it can hold up to the conditions we are considering here.

I almost hesitate to ask ... could LOX fit into this scenario? I like the idea of having docking capability as well as orbit circularization. The flight time should not be great, if the launch takes place so the cargo arrives as the customer facility passes overhead.

For SpaceNut re #132 ... thanks for the reminder of some of the trades at work here. Your point about testing is a good one. Failure of the wall of a fuel or oxidizer chamber would be messy for the launch facility. Theory can help, but ultimately, the development team is going to have to take the risk of trying whatever design is chosen at full power.

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kbd512 · 2020-03-29 21:34:22

tahanson43206,

LOX is pretty much the only oxidizer I've considered, whether we're talking about conventional liquid propellants or hybrid solids. Of all the available oxidizers, we have more experience with LOX by a country mile. Apart from horribly toxic Fluorine-based oxidizers, LOX also tends to provide the best performance in terms of both specific impulse and impulse density (for an orbital launch system, not necessarily for in-space propulsion systems).

tahanson43206 · 2020-03-30 07:09:51

For kbd512 #135 and topic in general

Thanks for your endorsement of LOX ... A practical concern I have with a liquid solution is handling at the launch site. A lower specific impulse bi-propellant that could be loaded at a ground facility and allowed to sit for days while the launch slot opens for a given shipment would be a lot easier to manage.

I will toss this next idea out for your consideration, knowing in advance that the energy content is so much less.

If the amount of thrust needed for orbit circularization is provided by something else (such as a solid), then a sphere of compressed oxygen might have the capacity to support docking, if used judiciously. Such a sphere could be loaded ahead of a launch, and topped off just before the vehicle is dropped into the chute, if necessary.

The idea I have in mind for this system is extreme simplicity, reliability and mass producability.

Solid fuel for the orbit circularization was Dr. Hunter's original idea (as I remember his writings) and I think that concept makes a lot of sense. It would also make one or more manufacturers of solid fuel rockets happy, because there would be a steady business for them if we can put this together.

At some point, in building a consensus around the concept, support by an architect or two wanting to design a large space habitat using cargo vehicle bodies would be a nice plus.

I'm starting to think of the nose section as having even more functionality, so that it can justifiably be collected and brought back to Earth for re-use. The nose section could have the docking propulsion system, which would open up after the vehicle leaves the atmosphere. The solid rocket section could be equipped with explosive bolts to remove the nozzle from the base of the vehicle, to effectively snuff the solid it it has reached the needed orbit and is still burning.

This next section is for a forum reader who just found the forum, and is reading messages in the active list for the first time:

This topic was started by kbd512, and he is the topic manager.

I am working on a specific subset of the many ideas which have been posted here in recent weeks.

See Post #2 of this topic for a quick summary of the features of the subset I am working on.

If you ** are ** qualified to help develop this subtopic, or ** any ** of the ideas posted in this topic, please register and contribute.

Edit#1: SearchTerm:LastPost

The most recent post in this topic was #137 at Today 07:44:45 on 2020/03/30
The most recent post in this topic was #138 at Today 11:02:09 on 2020/03/30

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Last edited by tahanson43206 (2020-03-30 09:05:24)

kbd512 · 2020-03-30 07:44:45

tahanson43206,

As a practical matter, this is an orbital bulk cargo shipment system. Whatever fits that also won't be destroyed by the launch is going to ship and the only real schedule is "as fast as you can safely get it into orbit". Nothing is going to "sit on the loading docks". We're limited to powders, liquids, metals, plastics, and fibers, but when it comes right down to it that's most of what we would use to construct or load an interplanetary transport vehicle with. I'm focusing on bulk commodities that are inexpensive but heavy, therefore unnecessarily expensive in terms of the fuel required to transport them to orbit using a conventional rocket, yet also necessary to sustain life. We need fibers for inflatable habitat modules and clothing. We need metals and ceramics for structural members and engines and tools. We need plastics for radiation shielding and lots of ordinary everyday items like toothbrushes and food containers and eating utensils. We need liquids for drinking water and propellants for propulsion. If we could limit rocket propulsion to delicate electronics and people, we could sustain the costs of a Mars colonization endeavor.

We're not going to ship hundreds of pounds of fuels for each pound of payload delivered. We don't do that here on Earth whenever there's a more energy efficient and therefore less costly alternative. The notion that we're going to create a second civilization on another planet without inexpensive transport is absurd. Even if the rockets were free, which they're certainly not, the average person doesn't have enough money to pay the fuel bill just to transport their person to Mars and nothing else. Since there's literally tons of other stuff required to keep them alive long enough to get to Mars, that clearly doesn't work. As such, this is our affordable and therefore practical alternative. It's not a replacement for a vehicle like Starship, but may be the only feasible way to make the transportation costs affordable enough to be feasible for your average construction worker or school teacher until those teleportation or anti-gravity drives materialize.

SpaceNut · 2020-03-30 09:02:09

Boiloff occurs for any cyrogenic fuels or oxidizer so there will be no days let alone a single day for those fuel types. When missions get scrubbed the fuels are unload if the flight does not happen within hours. That leaves solids if that is a requirement to have it ready to go at all times.
From an earth stand point there is a priority list of things to ship to LEO to support and there is a list to allow for expansion. There are also lists of needs to move beyond LEO for the needs of man once established there. One only needs to look at the ISS for the first 2 lists to acknowledge what we need to get to orbit in a cheaper fashion.

kbd512 · 2020-03-31 00:27:16

Why would you not have an on-site LOX plant?

What cost or complexity advantage does shipping LOX to the launch site confer to the overall solution?

tahanson43206 · 2020-03-31 07:26:19

For All .... Calliban inspired a series of posts in another topic, about electromagnetic launch.
The link to a post about launch of 1 Metric ton is given here:
http://newmars.com/forums/viewtopic.php … 64#p165764

A question posed to Calliban has been addressed by kbd512 in this topic. kbd512 has proposed using the rotating mass energy storage system developed for the US Navy electromagnetic catapult system.

For kbd512 ... I went back and re-read your Post #5, and in particular, I read the NASA paper you linked in Post #5. With all the other content in Post #5, I appear to have overlooked the link. It reports on a study competing with a Titan launch, using an EML for just over Mach 1 launch of a ram jet flying vehicle, which itself was carrying a rocket stage for delivery of payload to orbit.

The detail that I found most helpful was the lengthy presentation on the linear motor that was designed and modeled with live tests. The use of an aluminum keel was a detail I'd not seen before. The use of aluminum in other designs for magnetic levitation devices was familiar to me, and I have seen a working demonstration of magnetic levitation on an aluminum base.

A detail I found interesting was the decision NOT to worry about magnetic levitation for the launch sled.

Today, I'm planning to add another session done with Physics 101, to study the specific cases of launch to LEO and launch to Escape.

SearchTerm:Physics101

2020/03/30 Notes for NewMars EML Discussion

Physics of EML (ElectroMagnetic Launch)

Reference: Physics 101 Version SE 8 (9/15/2010)

Conditions to be studied:

1)Mass of vehicle: 3 metric tons
2)Payload delivered to Low Earth Orbit 1 ton
3)Range of capability of EML: 100 km minimal orbit to escape
4)Length of EML: 1 km

Results to be delivered:

1)Velocity of vehicle upon exit from launcher
2)G forces experienced by vehicle over range of orbits
3)Times to be expected for various phases of launch
4)Ballistics computations (note lack of gravity gradiant) (*)

(*) The Physics 101 program does not reduce gravity with altitude

Topic 1: Velocity of vehicle upon exit from launcher

A. For low Earth orbit, required velocity is (about) 7.8 km/s

Wikipedia/Low_Earth_Orbit gives 9.4 km/s delta V needed
this value includes atmospheric and gravity drag. [9400 m/s]

In practice, if a rocket is fired to achieve orbit circularization, the velocity at exit from and EML would be less than 9.4 km/s. However, that velocity is a useful starting point for calculating stresses on the vehicle, and capability needed for the EML.

B. Escape Velocity

Wikipedia/Escape_Velocity gives “about 11.186 km/s” A vehicle to be launched from an EML would need more delta V. Using the example for low Earth orbit, which suggested 9.4-7.8 km/s or 1.6 km/s, the comparable sum for Escape would be 11.2+1.6 or 12.8 km/s [12800 m/s]

Physics 101 session:

Compute Velocity for Orbital launch (Find Acceleration)
Given initial velocity: Zero
Given track length: 1000 meters
Find velocity if acceleration is 45000 meters per second squared
Velocity is: 9486+ meters per second
G force is 45000/9.8: 4592- G's

Compute velocity for Escape: (Find Acceleration)
Given initial velocity: Zero
Given track length: 1000 meters
Find velocity if acceleration is 82000 meters per second squared
Velocity is: 12806+ meters per second
G force is 82000/9.8: 8367+ G's

Now find the time required:

For orbital velocity:
Given initial velocity: Zero
Given final velocity: 9486 meters per second
Given acceleration 45000 m/s(squared)
Time is: 0.211 seconds

For escape velocity:
Given initial velocity: Zero
Given final velocity: 12806 meters per second
Given acceleration 82000 m/s(squared)
Time is: 0.156 seconds

These results are consistent with the ones developed earlier for the One Metric Ton case.

They lead to the observation that the length of time required for all the launch scenarios considered is under one second for a launch length of 1 kilometer.

I am skeptical that humans living in 2020 are capable of building a linear motor able to deliver performance at this level. I read your early optimism in this topic, and hope you are right. However, there is a significant difference in degree of performance from pulling 50,000 pounds to 150 miles per hour, and pulling three tons to 9.4 kilometers per second, let alone 12.8 kilometers per second for Escape.

(th)

tahanson43206 · 2020-03-31 11:16:28

For kbd512 re topic

In pursuit of an answer to the question if linear motors can deliver the velocity required for the EML of my subtopic, I asked Mr. Google:

Today, linear motors typically reach speeds of 5 m/s, with high accelerations of 5 g in practice. Theoretically, motors can reach over 20 g with 40 m/s velocity.
Linear Motors Application Guide - Aerotech

That citation in the results list includes a link to a pdf which I hope will explain how the maximum capability of 40 m/s velocity is determined.

40 m/s is only 89 mph. The real world already exceeds the prediction in the citation, if reports of US Navy catapult performance are correct.

Alternatively, the US Navy catapult may be using a technology OTHER than the one studied in the citation.

In any case, if a forum member cares to help out (someone in addition to kdb512, SpaceNut and myself) there is an opportunity here for them to pitch in.

If a forum reader is NOT already a member, and is both able and willing to make a contribution, please register and do so.

The velocity to be achieved for Escape velocity is 12806 meters per second.

It should be noted (for the ambitious among us) that Dr. John Hunter was initially asked to try to find an EML solution for Star Wars projectiles. He gave up on that avenue of research, and went to Hydrogen gas guns, where he achieved documented results.

I am hoping it will turn out Dr. Hunter's options were limited by the technology of the time, and that another look at possibilities might yield a bit of encouragement.

(th)

Last edited by tahanson43206 (2020-03-31 11:19:39)

SpaceNut · 2020-03-31 15:37:22

Linear motion (also called rectilinear motion ) is a one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion with constant velocity or zero acceleration; non uniform linear motion with variable velocity or non-zero acceleration.

https://www.engineeringtoolbox.com/moti … d_941.html

Linear motor sizing is relatively straightforward when the proper mathematical relationships are used. Given a moving mass and motion profile, the equations of motion and a few motor parameters can be used to calculate a motor’s temperature rise.

Calculating Linear Motor Requirements

Part of the issue for levitation is mass for the rocket and distance that we need for the seperation once we start to launch along the length of the track. I was reminded on a none mass ability to float on a cushion of air...when I thought of the old air hockey table that was blowing air out tiny holes in its surface and just how fast the puck moved accross the table once hit. A plastic puck is very light but just how much force must the air provide to lift the rocket from its cradle in order to make a near friction less launch possible.
I am thinking that a semi circular launch ramp for the rocket to ride in with lots of air flowing into the areas of the track where the rocket is turning it on/off as it get by where it is not to keep the rockets mass off from the air slide.

tahanson43206 · 2020-03-31 17:40:41

For SpaceNut re #142

I like your idea of using air molecules for lubrication/elevation of the moving cargo vessel.

Along that line (and building upon your thought), it could turn out that the shape of the vehicle could be designed to interact with the shape of the track, so that air in front of the vehicle flows preferentially between the vehicle and the bed of the track.

It is possible you have not yet had a chance to study the linear motor design that kbd512 brought to our attention in Post #5 of this topic. If you ever have time to take a look at it, scan down until you find the illustrations of the working model, and beyond that, to the rendering of what a full size launcher might look like. What I'd like to bring to your attention is that the drive plate is a thin sheet of aluminum which travels between two banks of magnets. It is the aluminum which receives the thrust from the motor. The aluminum then delivers that thrust to the vehicle.

Thanks again for your suggestion to use air itself as a lubricant.

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Last edited by tahanson43206 (2020-03-31 17:41:44)

SpaceNut · 2020-03-31 18:33:21

Aluminum is a magnetic field blocker...It can conduct power or current through it buts used to isolate magnetic field.
I will see if I can get #5 link to display for me.

tahanson43206 · 2020-04-01 08:55:36

For SpaceNut re #144

It appears that the two of us are the only ones actively working this problem, and (I suspect) you are doing so partly out of a sense of duty to your members.

Until we can bring more knowledgeable and experienced people (like electrical engineers who work with linear motors) we are going to have to try to puzzle this challenge out on our own. kbd512 is the topic manager, and he has shown the way forward, but I think it is unfair to expect kbd512 to take more than a high level view, with the occasional deep dive to keep things moving. An example of that all important occasional deep dive is the link you are going to try to pull up.

Overnight, I realized that the design published by the NASA team can be extended from a single aluminum blade travelling along the linear motor slot, to four of them. I was concerned about the forces involved in this operation ripping the lugs right off the aluminum plate where they enter the cutouts in the cargo vehicle body., The strain on individual lugs can be reduced by increasing the number of motors to four, and increasing the number of lugs by as many will fit on the length of the aluminum keel.

The strain on the (probably steel) body of the cargo vessel can be distributed over the entire cylinder and over the entire length of the cylinder using this technique.

Finally, I suspect that the forces at work during the acceleration shown in the Physics 101 post earlier in this topic will melt (or vaporize) the aluminum keel.

Here is a direction I propose looking at this stage of the investigation, in the absence of participation by others with more knowledge and experience.

It would (seem to me to) make sense to take the existing performance of the US Navy EML as a base line, and find out what G force the system is able to generate over the short distance of a fighter aircraft launch. That would be the floor from which to build.

Given the proven acceleration capability, it would be possible to determine how long a track would have to be to deliver launches at LEO and Escape velocities.

All this work has been done before by others, and it has been done multiple times, without a doubt.

However, to the best of my knowledge, that work does NOT show up in this forum, so this topic is as good a place as any to add it.

If there is anyone who is a member who would like to make a contribution, this is a good time to do so.

If there is a forum reader who has the education and experience to make a contribution, and the generosity of spirit to do so, please register and post something.

For SpaceNut re #144 ... Among the useful knowledge to be added would be a precise analysis of how a piece of aluminum can be caused to move in a magnetic field. The fact that it CAN is shown in the link in Post #5. The physics of the interaction of the field coils of the linear motor, and the aluminum plate, are currently NOT documented in this forum.

In case someone is tempted to toss some conjecture into the topic, please take the time to collect references before posting.

Dr. John Hunter gave up on this long ago. Let's find out if advances in technology justify another look.

(th)

SpaceNut · 2020-04-01 11:12:21

Nasa link is from 2009 for post #5...

Page 1 of the pdf last sentence tells the type of motor design which is inductive.
The rotor is the inductive part in the design which uses different metals to do a lead lag of currents created by the fields to push and pull by reflection and attraction as pulsed with the help of a capacitor to complete the current circuit.

The pulse timing cycle is what will make the motor rotate faster and faster as the timing of the pulses are made shorter and shorter.

An example of an AC 60hz inductive motor is a window fan.
A dc source voltage with a switching device while it looks like AC to the motor is pulsed DC with a frequency that can be changed. Other features to that psuedo AC signal voltage is that we can limit the current and the voltage to the coil and that also changes the power going into the motor to make it move as controlled torque.

tahanson43206 · 2020-04-01 11:51:39

For SpaceNut re Post 146

This post seems like a great start in developing a series of posts that could be read by a high school level science student, to understand the physics demonstrated by the NASA test article in 2009. As you can see in the diagrams and photographs in the pdf, a long aluminum plate is held between two sets of magnets.

Aluminum is an interesting material for a number of reasons. One feature of aluminum is that it is NOT attracted to a magnet (see citation below).

In Post #146, you've started along a path that (I'm hoping) will lead to understanding how a strip of aluminum could be propelled by magnets, let along used to pull a cargo pod along with it.

Google found this, to help us get started, in the absence of someone knowledgeable with experience.

The best answer is to say that it is not magnetic under normal circumstances. But it's always impressive to show them the can demonstration and how it can interact with magnets. We can say that in strong magnetic fields aluminum can become slightly magnetic but in everyday experience it does not exhibit magnetism.
Is Aluminum Magnetic? - TerpConnect
terpconnect.umd.edu › ~wbreslyn › magnets › is-aluminium-magnetic

Edit #1: This image is part of an article on linear motors. The illustration shows a NASA design for an EML, dating to 1999. The deep slot for the aluminum keel is visible:

https://cdn4.explainthatstuff.com/linearmotor.jpg

The article itself may be seen at: https://www.explainthatstuff.com/linearmotor.html

Edit#2: The article contains a list of related books and citations of articles.

It includes an illustration of a train system patented in the 1960's, which has some similarity to the system NASA designed for the 2009 paper.

The difference is that the magnets are mounted in the bottom of the train and they work against the rail. In the NASA design, the magnets are mounted in the track and they work against the keel of the sled. Interesting (to me at least) is that the 1960's design for the rail system used your suggestion of air flow as lubricant for the cars of the train.

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Last edited by tahanson43206 (2020-04-01 12:11:59)

tahanson43206 · 2020-04-01 12:24:48

For SpaceNut ...

Inspired by your post #146, I decided to ask Mr. Google about "science experiments linear motor"

This was a fruitful inquiry!

The first page was about half full of directly related citations, before the inevitable drift began. Even the top drift articles were somewhat related.

There are 9 (nine) videos to start things out!

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SpaceNut · 2020-04-01 18:02:12

Having magnets are not inductive for motor design in the clasic sense. Magnets make it a motor generator type and depending on if you are making the parts that turn will determine what is going to be done..

This paper proposes a system that is composed of a
ground-based Mach 1.5 electromagnetic catapult,
a Mach 4 reusable ramjet, and a
chemical rocket second-stage -to-orbit.
Current orbital delivery costs can reach $10K/lb.

The linear stator coils are on page 9 of the motor
In a round motor the rotor would house the shaft to make the motor function which is the part of the inductive motor.

Here is the drawing of a typical rotating motor

The outer part is the stator and the inner is the rotor.

The design which they have is one where the voltage is ramped upward to increase speed at a fixed frequency.
variable voltage variable frequency (VVVF) converters for variable speed drive (VSD)

The slide that is in between the stator coil is a reaction plate or the flat rotor and its not just aluminum.

The inductive motors stator are usually made up of laminate steel and the rotor is as well but its got alternating materials and shape for how they are staggered.

Squirrel cage rotor type, which comprises a set of copper or aluminum bars installed into the slots, which are connected to an end-ring at each end of the rotor. The construction of these rotor windings resembles a ‘squirrel cage’. Aluminum rotor bars are usually die-cast into the rotor slots, which results in a very rugged construction. Even though the aluminum rotor bars are in direct contact with the steel laminations, practically all the rotor current flows through the aluminum bars and not in the laminations.

http://ww1.microchip.com/downloads/en/D … 0motor.pdf

https://electrical-engineering-portal.c … ion-motors

tahanson43206 · 2020-04-01 18:50:42

For SpaceNut re #149

Thanks for taking a look at the NASA paper kbd512 showed us!

It is easy to become distracted by rotating equipment, as shown in #149

This subtopic is focused upon linear motors, with the specific example provided by kbd512 of whatever the US Navy is using to accelerate aircraft on the Gerald R. Ford. NASA's 2009 paper shows an example of a linear motor designed to accelerate an object such as a flight vehicle.

This citation showed up when I asked Mr. Google to look for articles about linear motors:

Linear Induction Motorslink.springer.com › content › pdf
Current world-wide interest in the design and use of linear ... by the normal rotating machines (ie that the rotor must be ... the fixed aluminium alloy rotor plate.

The citation mentions "aluminum alloy", so I expect that with a bit of searching, we may discover the optimum alloy for this application.

Keeping focus on the problem to be addressed:

The goal is to find a solution that can accelerate a cargo vehicle to 18,000 meters per second, if the laws of physics do not forbid it, AND if the reality of operation in practice allows it.

If anyone can find the exact performance for the US Navy catapult design, that would be helpful. We already have available the approximate mass of the aircraft launched, and we have a speed of 150 miles per hour as a reasonable estimate of velocity of the aircraft at the end of acceleration. What I am unsure of is the length of the track, and the time expended from start of acceleration to the end.

(th)

Last edited by tahanson43206 (2020-04-01 18:51:25)

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