electromagnetic launch with microwave propulsion

SpaceNut · 2020-03-10 17:42:02

Attributes for launching a payload to orbit.
1 payload mass
2 fairing or payload shroud may include adapter to hold and mount payload to rocket
3 circulation stage mass
4 booster stage mass or masses if more than 1 is needed.
5 remaining momentum to transfer to rocket plus payload
6 air speed resistance drag loss unitl booster fires
7 exit speed from ramp unit

https://www.scientificamerican.com/arti … -distance/

Key concepts: Physics, Velocity, Acceleration, Gravity 9.8 meters per second (m/s)

https://physics.info/drag/

https://www.engineeringtoolbox.com/incl … _1305.html

tahanson43206 · 2020-03-11 09:16:22

This is for kbd512 re topic, and specifically, creation of a 'point in time' branch.

There is precedent in the forum for what I am about to propose for your consideration. Louis created his "City on a Plain" topic, and came up with "Sagan City" as a name, and then (with a bit of prodding) Louis selected a site for the location of Sagan City. Louis then washed his hands of it. I picked up the concept and launched the My Hacienda topic with a long term set of objectives. The topic remains "alive" in the sense that it is ready for development by new volunteers who would be invited to join the forum for that purpose. I am still trying various ideas to publicize the opportunity, and to try to make it attractive to serious participants.

In the case of the EML topic you have created, I think there is a possibility that something like what your topic here has imagined could come into existence.

However, ** this ** topic is in a constant state of flux as new ideas appear and old ones are discarded or modified.

I'm hoping you will support the idea of my creating a branch of this topic which will try to reduce the uncertainty that goes with the creative process, by selecting specific parameters and fixing them in place so that decision makers can begin to think about costs, time lines, resources and everything else that would be involved in creating a large scale launch complex.

Your vision of microwave supplementary energy supply is attractive, but for the sake of the goal of reducing uncertainty, I'd like to trim that particular aspect of your vision from a first cut at a real world plan. It could most certainly be added later, either as a way of contributing energy to a flying vehicle, or as a way of supplying energy for launches, which has the advantage of less complexity on the ground as a trade for increased investment in space.

SpaceNut has affirmed that "management" of a topic is available to topic creators. Most topic creators in this forum appear to be willing to encourage diversion from the original theme, in order to encourage creative thinking that comes with the ongoing brainstorming that is characteristic of this forum.

What I'd like to try with a new topic which branches from this one is to (try to) exert a bit more guidance for content to be added or modified.

The new topic (as I am imagining it) would become a repository of knowledge about the specific topic, which anyone could pick up with confidence for application to similar facilities anywhere in the World.

(th)

SpaceNut · 2020-03-11 17:40:05

I do agree that the focus should be to solve the launch system in totallity and leave the microwave to later after a system is working.

kbd512 · 2020-03-13 22:11:37

tahanson43206,

I thought I was fairly explicit in that the initial goal for this program was to remove the requirement for a booster stage (apart from reentry heating, this is what drives the incredible cost of orbital class rocketry), test with a sub-scale model possessing significant payload capability (1t initially, with a design goal of 5t), to use conventional rocket propulsion technology until such time as follow-on programs can be implemented to further reduce the fuel requirements (apart from rockets, we don't have any other production-ready hypersonic engines), and to simplify the rocket propulsion system by using a hybrid solid rocket with substantial density impulse (to reduce the size and therefore cost of the vehicle) and improved specific impulse (and to accomplish this without exotic or hazardous propellants).

I want engineers to prove how clever they are by designing and building a practical, affordable, and reliable system that's only as complicated as it needs to be to achieve the aforementioned launch system project goals. Running up the cost with brand-new, untested, whiz-bang gadgets is not the plan here. This should be an exercise in electrical and mechanical engineering, not ground-breaking new propulsion technology.

This is the kind of rocket engine I had in mind:

Hickam CDR

When combined with a 3D-printed support matrix of plastic, a paraffin wax fuel has the right properties to increase specific impulse very near to the range of the RD-180 (and paraffin waxes are also around 15% denser than kerosene):

Wax Fuel Gives Hybrid Rockets More Oomph

If we don't come up with something significantly cheaper and easier to use than what we have now, very few of us are leaving this planet on account of cost alone.

We've been messing around with chemical rockets in a serious way for the better part of a century. At this point, no significant improvements to specific impulse are likely to materialize and thus the only way to reduce launch costs is to offset some of the energy requirement to attain orbital velocity with something substantially more efficient than burning massive quantities of chemicals. This particular plan does not require development of any fundamentally new or untested technologies, so it's mostly a matter of scaling up existing and well-understood technologies to the point where they're suitable for orbital launch.

tahanson43206 · 2020-03-14 07:29:11

For kbd512 re #54

Thanks for addition of clarification and more suggestions for design of an EML system to put 1 ton payloads in low Earth orbit.

As a visionary, you need the freedom to keep developing your ideas, and this forum is a great place for that to happen.

The problem I am facing is the lack of stability that is needed in order to enlist/recruit people to help.

The situation is not too different from trying to hire people to build a bridge, and the architect is constantly expanding his vision of where the bridge should go, how long it should be, what materials it should be made of, what loads it can carry and how it will handle natural phenomena like hurricanes and earthquakes.

Once a project team is set up to build a specific system, changes can still be introduced, but there is a limit beyond which the who project has to be discarded.

In the case of a wages-paid environment, it is hard on morale of workers, but at least they get paid. Since volunteers are "paid" only with satisfaction of collaborative achievement, changes to the point of discard can drain motivation out of individuals, and eventually out of the group.

What I would like to see come out of your initiative is a set of thoroughly vetted Open Source plans to build an EML in any location on Earth where the consequences of the activity can be tolerated, and where the economics are viable.

The plans should be sufficiently sound so that any of the hundreds of billionaires we have on this planet can take the risk of attempting to build the system.

I would trust the judgement of someone like GW Johnson, for example, to give the green light to a set of concepts you are willing to set in stone for the purpose of enlisting volunteers to contribute the detail that is needed.

I see significant challenges ahead, but am not personally able to see solutions:

1) A run from the surface of the Earth to above the atmosphere.

The distance is between 20 miles and 400 miles, depending upon the ability of the vehicle to bend its path upward

2) The noise level produced by the flight

The noise of successful launch can be alleviated by payment of dividends to those who live around the launch site.

3) The ability of the system to change azimuth

The launch facility can be designed to rotate, or the flight vehicle can adjust azimuth during flight through the atmosphere

No doubt there are other issues to be dealt with.

Thanks (if I haven't said so before) for providing the leadership here, that allows this topic to continue.

(th)

GW Johnson · 2020-03-14 10:05:56

Using high-school physics kinematics to find out what ball park we are playing in: speed 3000 m/s, max acceleration 50 m/s^2 (just over 5 gees) for human occupants. Desired altitude at end of run 20 km. V^2 = 2as gives s = 90,000 m = 90 km.

Rule-of-thumb for driving temperature for heat protection: deg K numerically equal to velocity m/s: 3000 K heat protection required by the time you reach end-of-track at 3000 m/s.

Nothing but the desired altitude is outside the "doable" with what we know at this time. We have built particle accelerators that extend over similar distances, and the supporting technologies for EM launch now exist, or that aircraft carrier would not be employing it. We have never built anything freestanding over 2 km high, and damned few such.

You are looking at a straight-line EM launch track 90 km long, up a mountain slope, to something nearer 3000 m = 3 km above local ground level, instead of 20 km above sea level. The track angle upward is on the order of 2 degrees.

That low end-of-track altitude means you will have heat transfer rates associated with sea level density instead of thin-air density, at a driving temperature near 3000 K. Those heat transfer rates are an order of magnitude, or more, worse than the thin-air problems we are used to dealing with. It will begin to affect your vehicle starting from the moment it goes supersonic along your track about 300 m/s. This heat protection problem far outstrips LEO entry heat protection, precisely because of being deep in the atmosphere.

So, the ballpark you are playing in is harsh for two reasons: (1) the very high heat protection requirements, and (2) the shock wave noise generated by moving Mach 10 at low altitudes, with the ground immediately adjacent.

Just for reference, a Mach 3 wave at 5000 feet is quite lethal to all on the ground within about a mile of the flight path. That was the major source of casualties expected from Project Pluto's nuclear ramjet cruise missile of about 1960. The second major casualty source was the hard radiation in the exhaust plume. The 1 megaton warhead was a distant-third source of casualties. So guess why we never built and flew this thing?

Just a bit of a reality check. Be fully aware of what ballpark you are really playing in. It's not that EM launch cannot replace first stage rocketry, because it can. It's that you will pay some heavy prices elsewhere, in order to afford that particular savings.

GW

Last edited by GW Johnson (2020-03-14 10:11:10)

tahanson43206 · 2020-03-14 15:40:52

For kbd512 re GW Johnson #56

It would be normal (for me at least) to feel a bit dejected by the facts provided in #56.

However, i am hoping for (and counting on) a response that accepts these elements for planning, and proceeds forward with what is possible.

The first suggestion I have is to change your thinking away from exceeding the velocity of sound at the launch point.

While GW Johnson has pointed out the (pretty clear) advantage of a launch up a mountain side, I believe anyone who looks into this will find that nowhere in the United States is there a location where such a facility could be constructed.

In other words, I ** like ** your proposal to launch from a horizontal facility.

However, your vision is going to have to adapt as the rules Ma Nature sets down (as revealed by GW Johnson in #56) , but then go on to provide inspiration for those who may be (hopefully will be) inspired to undertake the detailed research that would be needed to develop a practical plan.

Good luck! I (at least) am counting on you!

(th)

kbd512 · 2020-03-14 17:36:27

GW,

Although I'm still alive and well after a number of very close supersonic passes from fighter jets flying overhead (within a couple hundred yards or so), it sounds like what we need is an island in the Atlantic or Pacific. That should alleviate the problem with low level hypersonic flight close to inhabited areas. Perhaps some kind of exclusion zone near the launch facilities is also mandatory, not significantly different than a launch pad.

tahanson43206 · 2020-03-14 18:34:24

For kbd512 re #58

See what I mean about branches ? The idea of launching from a land mass such as Texas has (more or less) magically changed to launching from an island somewhere far away from the US and all its business activity.

A quick search via Google revealed a long list of uninhabited islands. Every last one showing in the top level list is beloved by the natives of the nation which include the islands in their territory, and many are protected wild life preserves.

Can i at least ** try ** to invite you back to the main concept, which is (or at least I ** think ** it is) to reduce the mass of a vehicle intended to transport a ton to low earth orbit.

If you change the scope slightly (well, maybe more than slightly) to envision an EML that moves a heavy mass to just below Mach 1 on the West coast of the Gulf of Mexico, you will have ALL the advantages that yields ... You can choose your azimuth. You can choose your angle of ascent. You can fly the primary vehicle back to the launch site. You can accommodate a wide range of vehicles by planning for that capability.

(th)

SpaceNut · 2020-03-14 19:32:16

To follow GW physics of high school
How to design and calculate a ramp

Gw gave us the ? in the image which is the ramp length but for the exit once at the top of the 2' grade is h for the sound that we will see. Second will the the Tsunami that will happen as the wave strikes the water.

https://www.mathopenref.com/trigprobslantangle.html

Since the ship is riding on a carrier platform we will not want to pull or allow it to impede the momentum we are trying to give to the rocket so lets launch it with the rocket and then release it with a parachute or use a musk payload fairing catcher.

That was due to the acceleration ramp length...suggesting noise level is also an impactor to doing on continental coast line. The map showed roads that are along the coast leaving little chance to launch from land.

kbd512 · 2020-03-14 19:32:39

tahanson43206,

I'm discussing an idea and at present, it's just an idea. The only way to determine the feasibility of an idea is to begin exploring the potential problems with an idea. I want people to actively poke holes in my ideas to discover the problems with my ideas. Sometimes a single person can't determine every issue that could possibly arise. That's why the idea needs to crystalize over some period of time wherein all the fundamental feasibility issues are identified and acceptable answers are elucidated to deal with those problems or, as is quite often the case, the idea isn't so simple and easy to implement, maybe to the point of being impractical with current technology.

You do recall the post wherein I stated that there's nothing inherently safer or easier about using this method of achieving orbital launch, right? It merely has the potential to dramatically reduce launch costs.

Achieving Mach 1 before leaving the Earth doesn't do very much to lower the mass and therefore cost of the booster and then you need to accelerate a much heavier 2 stage vehicle to Mach 1 and the vehicle has to withstand significant transverse aero loads in denser atmosphere, which also defeats the purpose of trying to design an electromagnetic launch system to deliver a lighter and smaller vehicle to orbit that uses less chemical fuel to achieve orbital velocity.

Initiating launch higher up in the atmosphere would be better from an aero loads, thermal loads, and sonic boom perspective, but then we'd need to fly a truly massive vehicle high into the stratosphere. Since we don't have any reusable hypersonic vehicles apart from conventional rocket boosters, we've just arrived right back at the original problem- we have a massive booster that's part of a 2 stage to orbit launch vehicle or an incredibly inefficient single stage to orbit vehicle. In either case, we have rocket hardware and fuel costs that are so great that the ordinary person has little to no hope of ever participating in space exploration and colonization activities.

I want to fly one vehicle back to the launch site. I want that vehicle to carry the payload all the way to orbit. I don't want to contend with the fabrication / fuel / maintenance costs associated with using a traditional chemical fueled booster. I don't want to design a traditional single stage to orbit vehicle either, because once again, the fabrication / fuel / maintenance costs are every bit as high, if not substantially higher, than a vehicle with a booster. We've already proven through decades of actual operational experience that the launch costs associated with those methods are unaffordable for the average person and the majority of businesses. You have to electrify some significant portion of the energy expenditure to attain orbital velocity to improve efficiency and the majority of the launch infrastructure needs to be associated with more readily maintainable ground-based assets. The giant hypersonic gas tank method doesn't improve affordability, no matter which way you try to do it.

By accelerating a very small hypersonic aircraft to booster burnout velocity from an Earth-based launch loop, we're eliminating the expenses associated with a booster and drastically improving the payload mass fraction as a function of the total wet mass of the vehicle. We're not going to build something multiple kilometers into the sky, nor are we going to use it to launch the largest aircraft the world has ever seen, nor any other potentially possible but fantastically expensive and therefore impractical way to deal with the physics associated with orbital launch.

Thus far, we've identified heat and noise as the actual physical impediments to making this new technology a reality. I seriously doubt we can do much about the noise except for keeping people away from the launch area- much as we already do with the exclusion zones around conventional rocket launch pads, but I think we have sufficient technology to deal with the heat for the 30 seconds or so that the vehicle will be subjected to tremendous aerodynamic heating.

SpaceNut · 2020-03-14 21:35:48

Lets start with the pegasus altered rocket:
Pegasus XL is a winged, three-stage, solid rocket booster that weighs approximately 23,130 kg (51,000 lbm), measures 16.9 m (55.4 ft) in length 1.27 m (50 in.) in diameter, has a wing span of 6.7 m (22 ft).
Pegasus is lifted by the OCA to a level flight condition of about 11,900 m (39,000 ft) and Mach 0.82.

So using the ramp to launch this rocket for a mach 1 speed would only be reducing the carrier plane.

The pegasus has the wing on the first stage and since we are trying to remove a styage that wing needs to change shape and size for mounting it onto the second stage when we redesign the rocket for the em launch system. The em launch system needs to achieve the speed that it would do after that first stage had fired and was spent to make the numbers.
pg17 of the pdf I gave for the pagasus has the mass, firing time, and thrust numbers of which the document is expressing the speed in feet per second or fps. pg 21 shows the second stage altitude and firing information at which we have the speed we need to be at.

tahanson43206 · 2020-03-15 07:18:31

For kbd512 #61

You ** should ** be able to reach your long term objective, by building a team with the required skills. Unlike in the case of Elon, you'll have to work entirely with volunteers who want to help you out of a spirit of generosity, and because helping you is rewarding because of a shared sense of hard work toward a desirable objective, and occasional success to overcome the inevitable disappointments as the team goes through the Try-Fail cycle.

SpaceNut has offered a vision of a potentially competitive fuel/supplies launch capability.

It seems to me, given that Elon is your potential customer for fuel and supplies delivered to orbit, you would want to build a team capable of achieving a fully reusable system able to operate out of a facility on land, in Texas if possible, and able to perform many launches per day for weeks at a time, AND able to do all that at a cost which is LESS than Elon would pay if he did it all himself.

The potential for cost savings are (or should be) discovered in:

1) Electromagnetic Launch itself
2) Use of oxygen in the atmosphere during the time when the vehicle is in the lower atmosphere
3) Design of fully automated vehicles able to operate without significant refurbishment between flights.

Once you have a fully operational launch capability competing successfully with other launch companies and with Elon himself, you'll have plenty of time and resources to spend developing greater capability.

As a reminder, there is a significant challenge just to build a team able to design an electromagnetic launcher able to launch a vehicle at a speed greater than (about) 150 miles per hour. Your design will deserve funding when it shows it can meet all the requirements for product delivery while at the same time, avoiding irritating the neighbors, both in the US and in surrounding nations you'll be overflying.

(th)

tahanson43206 · 2020-03-15 07:38:33

For elderflower re earlier comment/question about fuel containers delivered to orbit in support of a planned expedition to Mars.

I've been thinking about your comment/question.

The mass of the containers presents an opportunity. The containers can be designed to serve a purpose beyond their primary one, of holding fuel or oxidizer to be delivered to orbit.

We have a lot of talent available in this forum, and I'm hoping one or more members will think about the situation and post ideas.

However, as just ONE idea to try to "launch" the sequence, the containers might be designed to serve as links in a structure that would facilitate artificial gravity as a convoy makes its way to Mars.

SpaceNut has shown us at least one example of a rigid girder design proposed to allow for rotation of two or more vessels around a common center point. The fuel/oxidizer containers could be bolted together to make such a girder.

There is another aspect of this that recent discussion on the forum brings to mind.

There would appear to be a need for storage containers for liquid manufactured on Mars.

The shipping containers used to bring fuel/oxidizer to the expedition, and then used to make girders for the flight, could be unbolted and delivered to the surface of Mars (somehow) so they could be used to hold products on the surface.

I recognize the (somehow) is a problem to be solved, but the purpose of this post is to try to encourage systems level thinking.

(th)

SpaceNut · 2020-03-15 08:22:18

tahanson43206 wrote:

2) Use of oxygen in the atmosphere during the time when the vehicle is in the lower atmosphere

That would be the scram jet and while we are not taking the oxygen mass from launch there are issues with direct use as its not going to be dense enough as its not in a liquid form. The mass of cooling equipment plus energy system must be less than bringing it with launch so that at is time is not possible as we need more trials and testing to make the use more of a possibility.

tahanson43206 wrote:

SpaceNut has shown us at least one example of a rigid girder design proposed to allow for rotation of two or more vessels around a common center point. The fuel/oxidizer containers could be bolted together to make such a girder.

Thats the refueling depot topic but its not all that practical other than at a demo level for fuel cargo of a ton to orbit.

As for Try-Fail cycle that musk is using to build is not a good business model since it requires steady cash flow that you do not care about.

tahanson43206 · 2020-03-15 11:24:38

For SpaceNut re #65

It is difficult to keep up with changes in this topic. Your answer regarding a SCRAM jet would be appropriate if we were talking about a supersonic vehicle. However, I am trying to persuade kbd512 (creator of the topic) to consider accelerating the primary vehicle to just under Mach 1, and then holding that velocity while course changes are performed by ordinary jet engines until the vehicle is pointed along the azimuth needed by the customer to match orbital plane, and then lifted to the appropriate angle of attack for launch of the payload carrying stage.

Regarding the girder .... The example I was thinking of was NOT a fuel depot, although that is an interesting idea itself.

Instead, I was thinking of an example (which I ** think ** you provided) of a rotating system of rockets connected together to provide artificial gravity during a long flight from Earth. As I recall the example, a rocket was set in the center to provide a center of mass for the structure, and two other rockets were attached to a girder (or possibly a cable) that was itself attached to the center pivot rocket. The resulting system of three rockets could provide a modest amount of artificial gravity for the passengers and crew of the outer two rockets.

In order for the one ton fuel and oxiderizer containers to be sent to LEO to convert successfully into a girder for a Mars expedition, they would have to be designed so they could be bolted together in LEO, after their contents had been moved to the passenger vehicles.

It was ** that ** question from elderflower I was trying to address.

A fuel depot is an entirely different topic, which I propose not be included in this topic.

(th)

kbd512 · 2020-03-15 13:35:56

tahanson43206,

There's no significant cost benefit to accelerating something to just under Mach 1 using an electromagnetic launch. StratoLaunch can already do that right now without any additional infrastructure spending, but the cost associated with maintaining the airframe and the orbital launch vehicle isn't competitive with just maintaining a launch vehicle. That's why the holding company that owns StratoLaunch stopped work on the project and why SpaceX walked away from the project. I'm not interested in spending more money on another dead-on-arrival project.

The entire point of this project is to dramatically reduce the fuel consumption and launch vehicle hardware requirements. The only feasible way to do that is to eliminate the booster, replacing the extreme quantity of chemical fuels used, relative to the mass of the payload delivered, with cheaper and more efficient electrons. There's a very compelling cost argument for the cheaper fuel / consumables / equipment deliveries that you could send to orbit to support interplanetary vehicles such as Starship, meaning around 2/3rds less fuel and hardware to deliver small (1t to 5t) payloads for 1/3rd of the minimum possible cost of an all-chemically powered vehicle.

In the end, I'm trying to create a complimentary technology to provide fuel / water / engines / construction materials for Mars to use in conjunction with Starship Super Heavy of whatever else SpaceX comes up with. The need for giant spaceships isn't going away for colonization, it's only becoming more acute. However, the need for even cheaper delivery of supplies will also become more acute.

Imagine for a moment that we have 24 (2 squadrons worth) of these delivery vehicles and we could fly each vehicle 2 times per day. We need to deliver 1,200t of propellant to an outbound Starship. We can accomplish that in 5 days using 1/3rd of the fuel that Starship tankers would burn to deliver the same tonnage of propellant to the outbound Starship. Put another way, each Starship produced can be used as an interplanetary transport.

tahanson43206 · 2020-03-15 20:30:02

For kbd512 re #67

I regret being unable to verify your belief that there is no cost benefit to an electromagnetic launch. However, even if your belief is ultimately proven to be correct, I'm hoping you'll be interested in this quote served up by Google:

Top speed: 530 mph
Aircraft carried: Pegasus (previously proposed); Dream Chaser (previously proposed)
First flight: April 13, 2019
Number built: 1
Manufacturer: Scaled Composites
Registration: N351SL

From: https://en.wikipedia.org/wiki/Stratolaunch_Systems

First, the plane flew for the first time just under a year ago.

Second, I found no evidence it has flown since.

Third, there is only ONE of these in the world (that I know of) [The Russians have built large planes, and may have something this size]

To my eye, that is a very fragile aircraft. It is a very IMPRESSIVE aircraft, but my expectation is it is safe if flown VERY carefully.

In contrast, were you to allow yourself to consider an EML from Texas over the Gulf of Mexico at just under Mach 1, you would be offering a Pegasus customer a higher starting velocity than they can get with a plane that takes a long time to reach altitude. The EML launched carrier aircraft would be moving at just under Mach 1 in a minute or less of acceleration at ground level, and it would be holding that velocity for as long as necessary to achieve the azimuth and angle of attack needed for a launch of the payload vehicle.

What is more, potentially you could be offering launches at the rate of one per hour or so, and NOT annoying the neighbors.

No one has build an EML capable of launching a large mass at just under Mach 1.

It would take a super-salesperson to convince funders to take the risk of trying to build a heavy lift EML, even though a working version is deployed at sea right now.

Because your preferred direction sounds similar to railguns, I investigated a bit:
https://en.wikipedia.org/wiki/Railgun

In addition to military applications, NASA has proposed to use a railgun to launch "wedge-shaped aircraft with scramjets" to high-altitude at Mach 10, where they will then fire a small payload into orbit using conventional rocket propulsion.[5] The extreme g-forces involved with direct railgun ground-launch to space may restrict the usage to only the sturdiest of payloads. Alternatively, very long rail systems may be used to reduce the required launch acceleration.[6]

That about sums up the topic, except for the microwave energy supply idea.

I'd like to see a modest proposal come out of this topic, with a modest chance of winning funding, than an ambitious proposal that contains too many challenges for any but the most desperate of governmental agencies.

(th)

tahanson43206 · 2020-03-15 20:52:40

For kbd512 re topic ...

I just realized this topic was created in the top level category of "Human missions"

It appears that I contributed to departure from your original intent, in Post #2.

If you want to return to the original focus, then the option of delivering a passenger carrying vehicle to just under Mach 1 may look a bit more appealing.

The pursuit of EML for payloads would seem better suited for another topic category, although since one does not exist for launch systems, perhaps now is as good a time as any to ask SpaceNut to create one, or to ask for the Powers that Be to create one if necessary.

(th)

kbd512 · 2020-03-15 21:10:06

tahanson43206,

The problem is that you're going close to Mach 1 near sea level versus 40,000 feet. Afterwards, you have to pitch up and climb out of the thickest part of the atmosphere. You either forfeit much of the velocity provided by the launch to gain altitude or you spend more time climbing through thicker atmosphere with the aerodynamic drag, heating, and engine specific impulse performance penalties those issues impose on your launch vehicle.

High performance fighter jets like the F-15 and F-22 have climb rates near 50,000 feet per minute. Why not just fly a high performance fighter jet off a conventional runway and then launch a conventional rocket like Pegasus near 100,000 feet? That's be a heck of a lot easier to do, would use a rocket engine nozzle optimized for near-vacuum conditions (higher specific impulse), and there'd be a lot less heating and sonic boom issues to deal with.

As compared to a Mach 1 launch at sea level, StratoLaunch would provide a greater performance boost from starting the launch sequence at an altitude with less than 1/3rd of the sea level atmospheric density and a significant percentage of the same speed that the electromagnetic launch would provide. In short, you either accelerate really fast so that you only spend seconds climbing through the lower atmosphere or you're better off just starting higher up in the atmosphere where you can use a rocket engine with a nozzle specifically designed for reduced atmospheric pressure, which improves your engine's specific impulse.

I proposed the idea for the engineering advantage of booster elimination and fuel mass savings, not because I thought this was something particularly cool or simple or easy to do. Desperation is hoping that "building it bigger" will result in some kind of cost savings that rarely materializes, apart from cases involving mass production (which only reduce production costs, not operational costs). Nobody I know will be moving to Mars on account of the fuel costs alone. We either come up with something radically more efficient or the only people going into space will be astronauts and the odd billionaire.

SpaceNut · 2020-03-15 21:23:33

Have just moved the topic location as its a technology developement that is being worked.

Sub orbital carrier planes are large and the fuel is a slow burn such as the Shape Ship One.
So launching a the Mach 1 for those joy ride flights mean we are not going to orbit.

The benefit of a Mach 1 pegasus we can continue down that road but the cost of flight is just the carrier plane time and fuel once its fitted to it. Thats not really a savings and the Pegasus has still got to get to the engine firing location from that push from the ground altitude. It is a cargo only use vehicle as designed. All of the examples were all cargo launchers with only some needing to be lifted to altitude to launch from. None of which are reuseable.

The reality is that with a different rocket design being launched the fuels being used, engines there is a different market to be had for cargo to orbit.

tahanson43206 · 2020-03-15 21:56:45

For SpaceNut re #71

This Index level topic seems a better fit.

Regarding the carrier aircraft (Stratolaunch) ... That vehicle, impressive as it is, has only flown once, and has never launched anything.

It's potential is non-zero, but it's performance as a going operation is still zero.

kbd512 ... if you want to pursue the EML path, and you want to build a successful business, the single biggest obstacle I can see remains social ... There may be a technical solution to the sonic boom problem. I'd like to recommend you put that first on the critical path. Moving to a Pacific Island is not practical for a number of reasons, which I have tried to point out in a recent post.

From Google: how to prevent sonic boom

Can sonic boom be eliminated?
The key to eliminating the sonic boom is in the design of an airframe. In a conventional supersonic jet, the shockwaves coalesce as they expand away from the nose and tail - leading to two distinct sonic booms. ... Current regulations mean civil aircraft can only go supersonic over water.Jul 20, 2018
Is killing the boom the key to supersonic air travel? - BBC News
The trick is to shape the aircraft in such a way that the shockwaves remain separate as they travel away from the aircraft. This means they reach the ground still separated, generating a quick series of soft thumps.

OK kbd512 ... Perhaps that is the answer for your ground level Mach 6 vehicle travelling 400 miles over the Gulf to reach 20 miles altitude.

Assuming it is, I'm curious to know how much of your initial velocity will be lost to that 400 mile run. It may not be much, or it might be a lot. The same design of the shape might have a side benefit of reducing drag to some extent.

In any case, (to my knowledge) no engineering team has attempted to scale up a launch track to exceed 150 miles per hour.

Your funder is going to have to be convinced a lot of technical advances can be achieved by your engineering team.

Edit #1: Addressing the sonic boom problem, and extending from the BBC report:

If a vehicle were long and of (relatively) small diameter, perhaps it could be configured to generate sonic booms in a long sequence that would sound like a series of waves instead of a few large ones.

Perhaps the sound energy could be focused upward somehow ... in other words, the bottom of the vehicle would be flat, while the top contained whatever is needed to interact with the atmosphere to move it aside to admit the vehicle. The air molecules are ** still ** going to come back together with some vigor, after the vehicle has passed by. That is essentially what happens when lightning clears a path for electrons to move rapidly, and a temporary vacuum appears.

(th)

Last edited by tahanson43206 (2020-03-15 22:15:03)

tahanson43206 · 2020-03-16 07:49:27

For kbd512 re topic ... Accoustic Signature

SearchTerm:AccousticSignature
SearchTerm:Mach6Tone
SearchTerm:ToneLaunch

Yesterday, while standing in a very long line at a local supermarket, I struck up conversation with a gent ahead of me in line. I had asked if he would be impacted by the local announcement that all bars and restaurants were to be closed throughout the entire State. He assured me he would be, but not from that particular policy. He is a school teacher, and is scrambling to try to figure out how to teach his middle school students from home. His particular school is a public school, BUT it has somehow managed to provide every student with a laptop, so online learning is possible. The reason I am bringing this up is that the teacher's specialty is music instruction, and specifically wind instruments.

Overnight, I'd been thinking about the interesting problem of finding a way to make sending a projectile over the Gulf of Mexico at Mach 6 or so palatable to the population of the United States and Mexico which surround the gulf.

The research on sonic booms reported by the BBC (in Post #72) led me to imagine a design for the shape of the vehicle that would produce a tone, such as Middle C, when the vehicle passes overhead. If ridges are built into the cylindrical shape of a long pole shaped fuselage, for example, it seems reasonable (at this point of complete ignorance) to suppose that waves of sound could be created that would sum to a pleasing effect, which might render the flight less disagreeable to humans below.

In order to find out if there is anything to this hypothesis, it will be necessary to enlist/recruit persons with the appropriate education, experience and generosity of spirit willing to tackle this question as an Open Source, volunteer contribution to the NewMars forum.

If any existing member of the forum (or non-registered reader for that matter) knows of such a person, please let them know of the opportunity to help kbd512 with his quixotic ambition to provide an electromagnetic launch facility that will operate so efficiently and so effectively that it can compete with Elon Musk to deliver fuel and oxidizer, and other supplies for a Mars Expedition assembling in low Earth orbit.

(th)

kbd512 · 2020-03-16 10:54:52

tahanson43206,

Quixotic ambition though it may seem, we either find a better way or we continue to accept that each pound of payload delivered to Mars requires a bare minimum of 225 pounds of propellant, presuming only 5 Starship tankers required to refill the outbound Starship. That's 6,750 pounds / 1,907 gallons of LCH4 and 27,000 pounds / 2,834 gallons of LOX per 150 pound person. To put this in perspective, a Boeing 747 would burn 36,000 gallons of Jet-A / kerosene over a ten hour flight, which works out to roughly 90 gallons of jet fuel per person for a flight with 400 people on it. In terms of fuel alone, a single Starship flight to Mars is equivalent to just over 21 ten hour 747 flights. That's just the fuel required to transport your body mass and absolutely nothing else, not even life support. Nearly all of what makes transcontinental flights so expensive is the fuel cost. NASA allocates 1.84 kilograms of consumables per person per day for ISS operations, which equates to 728 pounds of food and water, just to make it to Mars. That requires another 4.85 times the amount of fuel and oxidizer on top of the fuel to send your body mass, just to keep you alive on the way to Mars. We're now up to 11,170 gallons of LCH4 and 16,579 gallons of LOX to send you plus enough food and water to survive the trip- fast approaching 1/3rd of that 747's entire fuel load per person delivered to Mars alive.

We have no way to keep you alive on Mars if we ONLY expend that amount of fuel, so are you beginning to get the idea that we're going to need something substantially more efficient?

Could you afford to purchase several 747 fuel loads for each member of your family?

Does cutting the fuel requirement to a still extravagant 636 gallons of LCH4 per pound of payload delivered seem like a better trade, especially if costs have to be managed at some level that permits someone who isn't a multi-millionaire from going?

The fuel and oxidizer is either going to have to be cheaper than water or we're going to have to find another way to even attempt to sustain something like what Elon Musk is planning to do.

tahanson43206 · 2020-03-16 14:18:34

For kbd512 re #74

I'm trying to help, but it is proving difficult. Could you please take up the concept outlined in Post #73 and think about it. You may know someone who could help directly. According to network theory, you are linked to someone who could deal with the issue, although the links may stretch out to six people.

What I think the research into sonic booms reported in the BBC article shows is that airframe/airfoil design can influence the behavior of the atmosphere through which a vehicle is passing. I think solving this problem is the most critical item on the critical path, so worrying about how to design an EML that does not currently exist is on the path AFTER this one.

I'd like to cast the net a bit wider ... if anyone currently in the forum, or who reads these posts, knows of someone who could speak to the challenge of modeling sonic boom behavior at Mach 6, please invite them to help out. They may decline, but they may decide the benefit to society is worth a little bit of their time.

My guess is that a problem on this scale is going to require some reasonably advanced fluid dynamics modelling software.

(th)

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