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Space Forum / Space Flight / September 2005Microwave beamed power
Has anybody investigated the use of microwave beamed power as a way of eliminating the first stage of a rocket? To put it more precisely to assist a rocket by beaming microwaves to it and to use these microwaves to heat the air as it goes through a ramjet like engine. Higher up where there is no air it could heat pure hydrogen that is expelled from a tank. This would be like a solid core nuclear rocket engine but would not have any radiation nor shielding issues. I am pretty sure that large amounts of microwaves can be cheaply made with vacuum tubes and beamed up by a ground based power station. I also know they can be received by antennas and converted to DC power by diodes, but this would not be the best way in this case. We would have to heat the hydrogen somehow using the incoming microwaves. Perhaps some kind of microwave absorbing tubes could be used that can also stand high temperatures. Like some kind of ceramic coated refractory metal. Any thoughts are appreciated. Z >Has anybody investigated the use of microwave beamed power as a way of >eliminating the first stage of a rocket? [...] You want to look to the work of Liek Myrabo. He's done too much to summarize easily in one posting, but he has looked at a large number of laser and microwave externally powered rockets and ramjets of various types. A number of his more advanced concepts are thought by other experts either to not work, or be so speculative as to functionally be science fiction. However, he also has done test flights of more nearterm practical stuff such as pulsed laser / air propelled craft using a large USAF IR laser, which amount to essentially all the actual flight test experience to date with externally powered rockets in an atmsophere. Other experts in similar areas include Jordin Kare, who is focused on laser propulsion. -george william herbert gherbert@retro.com Zoltan> Has anybody investigated the use of microwave beamed power as a Zoltan> way of eliminating the first stage of a rocket? Yes. They've looked at heating air, and also heating hydrogen. It's the second link when you google "microwave rocket". Have you just started using the internet? Issues: 1. You need a very big antenna array. 2. You need a very large electrical power source on the ground. Many many gigawatts, for even modestly large rockets. This is a problem because while producing gigawatts economically is well understood, it costs over a dollar a watt -- assuming you can spend many minutes ramping the power up and ramping it back down again. 3. Ramjets still suck, even if you have an external power source, because you have to collect and compress the air with something. What I have not seen, but I'm sure has been looked at: Rather than heating a solid surface with microwaves, then heating the air/propellant by conduction, it might be possible to select a propellant which is opaque to some frequency to which the air is transparent. Then the propellant can be heated directly, which eliminates the temperature limitation. The portion which is opaque need not be a huge fraction of the propellant mass, if it's well mixed. Also, one can imagine launching with LOX/LH2, then aquiring the beam, then ramping down the LOX injection rate as the thrust requirement drops, to ramp up the Isp at the vehicle loses mass. > [...]while producing gigawatts economically is well understood, > it costs over a dollar a watt[...] It does? Then how to account for this 40 kW generator for US$13k (which comes to ~US$0.33/watt): http://www.elitegenerators.com/40qumo50.html Or these (one of which comes to ~US$0.15/watt): http://www.electricgeneratorstore.com/sppa.html Granted, a natural gas gigawatt electric power plant may indeed cost ~US$1, but clearly it doesn't have to if it isn't intended to link into a utility power grid and meet all the other requirements of said grid connection. Perhaps the Isp of existing LH-Lox engines could be boosted by simply irradiating them from behind with a microwave beam. The nozzle could act as a focusing and receiving device and the water vapor in the exhaust would absorb some beam energy further improving the Isp of the rocket. The exhaust temperature could exceed conventional limitations because the center would be heated much more then the walls. Who cares what the energy costs? Zoltan Hydrogen is a great fuel, and so are hydrocarbons. Gaseous hydrogen and gaseous oxygen can be entrained in a spongelike hydrocarbon aerogel and create a mixture less dense than air! By controlling the relative ratio of hydrogen and hydrocarbon gel density can be controlled over a wide range. So, imagine a very long pipe that is equipped to manufacture aerogels that entrain gaseous hydrogen/oxygen mixtures. Imagine too the pipe varies the density of the aerogel/propellant string so that the string comes to rest at various altitudes - causing the string to trace out a synergic boost curve optimal to attain LEO. Now, we create a boost vehicle with a ramjet annulus. It boosts off the launch pad achieves supersonic flight and flies into the end of the string. The vehicle ingests the aerogel propellant string - detonates it - and derives thrust from it - tracking the string as it rises. In the end we have a single stage vehicle attain orbit. Once the first vehicle is on orbit, another string can be released and rise to its given altitude - so every 15 minutes or so, we can launch another payload into space by this technique. http://www.aiaa.org/content.cfm?pageid=406&gTable=japaperimport&gID=5200 http://www.aiaa.org/content.cfm?pageid=406&gTable=mtgpaper&gID=21706 http://www.aiaa.org/content.cfm?pageid=406&gTable=japaperimportPre97&gID=23768 This is one way. Another is to use laser energy to to ablate propellant from a solid block of plastic, and then use laser energy again to detonate that plastic into CO2 and H2O - creating a controlled blast of thrust. By creating millions of points of thrust across a surface any sort of lifting and control force can be applied to that surface. http://www.aiaa.org/content.cfm?pageid=406 This is another way >So, imagine a very long pipe that is equipped to manufacture aerogels >that entrain gaseous hydrogen/oxygen mixtures. > Boy, you had better hope you don't get a electrostatic discharge inside that string, or it's going to go off like a super-sized length of primacord. :-) >Imagine too the pipe varies the density of the aerogel/propellant >string so that the string comes to rest at various altitudes - causing [quoted text clipped - 5 lines] >it - and derives thrust from it - tracking the string as it rises. > That's somewhat similar to this idea: http://www.desertsecrets.com/i.chemtrail1.jpg http://www.desertsecrets.com/5,224,663.txt A real problem would be that the propellent string could be distorted by high altitude winds into a shape that the aircraft ingesting it would have a difficult time following. Here's what happened to the smoke trail from a Minuteman missile in fairly short order due to winds at altitude: http://www.freqofnature.com/photos/mmiii/P9192028.jpg That's from this page BTW: http://www.freqofnature.com/photos/mmiii/ Pat > Here's what happened to the smoke trail from a Minuteman missile in > fairly short order due to winds at altitude: > http://www.freqofnature.com/photos/mmiii/P9192028.jpg > That's from this page BTW: http://www.freqofnature.com/photos/mmiii/ That is some pretty fireworks show. Some pretty expensive fireworks show. Of course the contrail shown has zero lateral or tensile strength. Which is quite correct for the contrail of fuel patent you cited. Not so for the lightweight aerogel. A true analysis would look at winds aloft and determine the tensile strength needed to sustain a good enough trail of fuel and oxidizer. Clearly (see below) with a 16 kPa tensile strength, aerogels have sufficient strength to withstand considerable wind shear for some period of time. Hydrogen and oxygen will of course diffuse out of the gel over time, which will cause it to sag as time goes on. Which means the trail must be used minutes after it is in place. Rise times versus leakage times is an important ratio... Aerogel Specifications: Apparent density: 0.001-0.35 g/cc Internal surface area: 600-1000m2/g % solids 0.07-15% Mean pore diameters ~20 nm Primary particle diameter 2-5 nm index of refraction 1-1.05 Thermal tolerance to 500 C Coefficient of thermal expansion 2-4x10-6 Poisson ratio 0.2 Young's modulus 106-107 N/m2 tensile strength 16 kPa Fracture toughness 0.8 kPa*m0.5 Dielectric constant 1.1 Sound velocity through medium 100 m/s >Of course the contrail shown has zero lateral or tensile strength. >Which is quite correct for the contrail of fuel patent you cited. Not [quoted text clipped - 8 lines] >ratio... > As the air pressure drops around the ascending aerogel "propellant stick", the oxygen and hydrogen will leech out of the aerogel's structure unless it is covered in some sort of impermeable membrane. I still think there is going to be a problem regarding pre-ignition of the aerogel propellant stick- one static discharge anywhere within it, and your propellant supply gets turned into a giant fuel/air bomb. The other problem is how the oxygen and hydrogen get put into the aerogel in the first place; if this is to be done on the ground then it's going to require some sort of filling building several miles in length that can turn into the wind to release the filled aerogel cylinder through its roof, or a non traversing building that can only release in near dead calm conditions. In either case the two gases are going to stratify within the stick in fairly short order, with the hydrogen at the top. Getting the stick properly aligned for the TAV to ascend through is going to be a problem also; it must be aligned on the correct bearing for the intended orbit, as well as be floating at the correct angle to the horizontal for the intended ascent trajectory. This implies that the stick must be under control of some sort, most likely by being towed by an aircraft that attaches itself to the stick after it floats out of its gas loading shed, and then pulls it skyward to the intended altitude, trajectory, and ascent angle- probably at quite a low speed to stay within the structural limits of the aerogel. A helicopter of some sort sounds like a candidate for a tow aircraft, although this is going to badly limit the total altitude it can achieve. Pulling the stick through the air at even low speed is going to generate terrific drag given its length, and you are going to need a huge helicopter to even have a chance of moving and controlling it- something along the lines of a Mil-26 "Halo". Pat A closed cell aerogel is nothing but an impermeable membrane! Lots and lots of gas filled cells stuck together with each cell's membrane impermeable to the gases. No mixing of gases within the stick, no stratification of gases, no explosion risk while floating. Detonation occurs when the cells are mechanically burst by the passing of a vehicle which are mixed and heated by the shock effects. The building you imagine would be along the ground track of the vehicle under boost. It would not orient to the wind. The building wouldn't be a building either. It would be four pipelines in parallel. Two propellant pipelines, one aerogel precursor pipeline, and one mixing line - that opened along its length. Propellant and aerogel would be mixed in the mixing line - and the mixing line would then be opened. The effects of local winds over the length of the pipeline would largely cancel due to the immense drag of a miles long stick of material you already mention. The stick would take up the desired trajectory above the pipeline by simply changing the density of the aerogel along the length of the stick so that it came to rest at the appropriate density altitude. So, denser parts of the stick would hover lower in the sky than less dense parts of the stick. The angle of ascent would merely be a fuction of the difference in density along the sticks length. No helicpoters or other aircrat are needed to control it. Its immense size means that it will be little affected by light winds and by accurately controlling the density along its length - the altitude of the stick along its length will be accurately controlled - creating a precisely controlled trajectory for the vehicle powered by this propelant stick. [snip] >The building wouldn't be a building either. It would be four pipelines >in parallel. Two propellant pipelines, one aerogel precursor pipeline, [quoted text clipped - 3 lines] >pipeline would largely cancel due to the immense drag of a miles long >stick of material you already mention. [snip] Large Blimps and Zeppelins certainly care about winds... But you are probably just writng those off as "too small" and "local"... Ok, What about regional wind patterns. Say a low pressure center driving a circulation pattern several hundred miles across... What about coriolis? Since you are talking about making a thing that big, coriolis forces *are* going to be a problem. Since you are writing off "local" wind effects, then mesoscale effects must matter... how about pressure differentials between weather systems of several millibars... That will certainly mess up your nice smooth bouyancy curve. And my experience with hot air ballooning suggests that temperature will matter a *lot*... The very concept of these free flying bouyant "propellant sticks" that are supposed to be gobbled up by an ascending spacecraft is so full of obvious problems as to resemble a large swiss cheese. Gene P. Slidell LA  SignatureAlcore Nilth - The Mad Alchemist of Gevbeck alcore@uurth.com > Gaseous hydrogen and gaseous oxygen can be entrained in a spongelike > hydrocarbon aerogel and create a mixture less dense than air! And here I've been giving my kids helium balloons that last only a week or two. Where can I get some of this lighter-than-air aerogel? ,------------------------------------------------------------------. | Joseph J. Strout Check out the Mac Web Directory: | | joe@strout.net http://www.macwebdir.com | `------------------------------------------------------------------' > > Gaseous hydrogen and gaseous oxygen can be entrained in a spongelike > > hydrocarbon aerogel and create a mixture less dense than air! [quoted text clipped - 6 lines] > | joe@strout.net http://www.macwebdir.com | > `------------------------------------------------------------------' lighter-than-air aerogel? sounds like a good material to build aircraft from but it could become a very difficult to clean up form of litter. I wonder how pieces of it might affect jet engines or how it might feel on a windy day to have to dodge chunks of the stuff. Ken > > And here I've been giving my kids helium balloons that last only a week > > or two. Where can I get some of this lighter-than-air aerogel? [quoted text clipped - 3 lines] > wonder how pieces of it might affect jet engines or how it might feel > on a windy day to have to dodge chunks of the stuff. I was being sarcastic. No such material exists. Best, - Joe ,------------------------------------------------------------------. | Joseph J. Strout Check out the Mac Web Directory: | | joe@strout.net http://www.macwebdir.com | `------------------------------------------------------------------' > Has anybody investiassuminguse of microwave beamed powkineticca way of > eliminating the first stage of a rocket? The Powers are just HUGE. One SSME, assuming 100% energy conversion to kinetic energy of the exhaust is about 5GW . Thats 15 GW for the space shuttle. In practice you will need a lot more than this. This is Massive. Producting that kinda power in microwaves has only been done on paper and the reality is that its unlikely to scale up as nicely as you mite like. Bottom line. Chemical rockets are not as bad as you mite think. Greg If you could boost the Isp to say 1000 you would not need nearly as much power as 15GW. I have an experimental air breathing engine that generates about 1 MW of power in terms of the heat output of the propane burnt. This engine has a 7 inch nozzle and an Isp of 4000. To get to orbit at an Isp of 1000 you need a mass ratio of 2.5 To get to orbit at an Isp of 400 you need a mass ratio of 10 You could probably get the shuttle to orbit on 5GW received power. Zoltan [...] > I have an experimental air breathing engine that generates about 1 MW > of power in terms of > the heat output of the propane burnt. This engine has a 7 inch nozzle > and an Isp of 4000. That seems very good --- Armadillo's only getting an ISP of a few hundred on their biprops. Do you have any more information? One thing I do have to ask is, at what range of speeds will it air-breathe? Sucking in stationary air on a bench is a *very* different thing from running at hypersonic speeds in the upper atmosphere. Signature+- David Given --McQ-+ "...you could wire up a *dead rat* to a DIMM | dg@cowlark.com | socket, and the PC BIOS memory test would pass it | (dg@tao-group.com) | just fine." --- Ethan Benson +- www.cowlark.com --+ David Given <dg@cowlark.com> : > zoltan wrote: > [...] [quoted text clipped - 9 lines] > Sucking in stationary air on a bench is a *very* different thing from > running at hypersonic speeds in the upper atmosphere. He have been making this claim for over a year now. The one thing he seems to refuse to do is to test fly it. Infact, he will not even strap it onto a car and test it at low speeds (0-100 mph). For some reason he thinks his intake has no drag. Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp "zoltan" <zoltanccc@aol.com> : > If you could boost the Isp to say 1000 you would not need nearly as > much power as 15GW. > > I have an experimental air breathing engine that generates about 1 MW > of power in terms of the heat output of the propane burnt. This engine > has a 7 inch nozzle and an Isp of 4000. No, you don't. You have an air-breathing engine that at static workbench or at a fraction of a mach speed appears to work that well. What you don't have is a supersonic engine. As far as I know you still have not flown your design to see how it performs at even a good fraction of a mach. > To get to orbit at an Isp of 1000 you need a mass ratio of 2.5 > To get to orbit at an Isp of 400 you need a mass ratio of 10 > You could probably get the shuttle to orbit on 5GW received power. GW is a rate of power flow, not a total sum. That are other factors than just mass-ratio. That is why there are no beer-can size SSTO rockets being built. > Zoltan Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp > I have an experimental air breathing engine that generates about 1 MW > of power in terms of > the heat output of the propane burnt. This engine has a 7 inch nozzle > and an Isp of 4000. Jet engines are not rated in ISP, but fuel consumed per hour per unit thrust. They need air. > You could probably get the shuttle to orbit on 5GW received power. Higher ISP means more energy is put into the exhaust. Also it will be a neat trick to get a jet engine to work in a vacuume. greg. >> I have an experimental air breathing engine that generates about 1 MW >> of power in terms of [quoted text clipped - 3 lines] > Jet engines are not rated in ISP, but fuel consumed per hour per unit > thrust. They need air. Isp is the same quantity as specific consumption, but inverted, except that it's usually measured in seconds rather than 1/hours. Eg one pound of fuel per pound of thrust per hour is the same as an Isp of one hour or 3600 seconds. And 4,000 s Isp is 0.9 pound of fuel per pound of thrust per hour specific consumption. The presence of air doesn't affect that (although it's absence might :) (I have no use for slugs or poundals) SignaturePeter Fairbrother Peter Fairbrother <zenadsl6186@zen.co.uk> : > bob wrote: > [quoted text clipped - 17 lines] > > The presence of air doesn't affect that (although it's absence might :) Well the first problem is drag losses while the engine is breathing air. And so far Zoltan has refused to do any tests of his design where drag will be a factor. Second problem, is what happens inside the engine when air speeds at the intake reach Mach 1 and above. Zoltan again glosses over this. The problem with Zoltan's claims is he seems to refuse to do any tests off a workbench. For all I know the German V1 pulse engine rates an ISP over 1000, but I know for sure that it can't operate near or above Mach 1. Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp > Isp is the same quantity as specific consumption, but inverted, except > that it's usually measured in seconds rather than 1/hours. The reaction mass in a jet engine is *not* the same as in a rocket. They are apples and oranges. You don't buy jet engines rated in Isp. You don't buy rocket engines rated in specific fuel consumption. And lets face it. Jet engines don't work to well at 250,000 feet. Don't just compare on units. Its really a different measure. Greg The reason why we cannot use jet engines is because they are heavy. They are more of a burden because of their weight than they are worth. They also cannot be used over a wide speed range. At relatively modest velocities the intake compressors become useless. What I am working on is an engine that has the potential of overcoming these problems. I do the intake compression by a ventury effect and my engine can be very light because it is just an empty tube, similar to an ejector ramjet. It gives thrust over a range of velocities from zero to mach 6. Over mach 6 the same engine works as a decent hydrocarbon rocket engine with both fuel and oxidizer injection. see http://vtol.net/air.htm the diagram here shows approximate expected induction jet performance. As a useful thought experiment imagine what would happen if you simply took a conventional rocket and surrounded it with a large tube. Shortly after takeoff the rocket could turn off the oxidizer and fly on fuel only, to the point where either the velocity is too high or the altitude is too high and air breathing is no longer feasible. In the induction jet the engine generates thrust on fuel only at sea level at zero velocity. The intake system is only a drag in a conventional ramjet. In the induction jet the intake system contributes to the thrust. Zoltan "zoltan" <zoltanccc@aol.com> : > The reason why we cannot use jet engines is because they are heavy. > They are more of a burden because of their weight than they are worth. [quoted text clipped - 21 lines] > The intake system is only a drag in a conventional ramjet. In the > induction jet the intake system contributes to the thrust. What a lot of BS. You to date have not even run a test unit strapped to a car at 100 KM/H much less tried to get to Mach 1. There is no such thing as a dragless design and the fact that once you get pass the speed of sound in your air flow it is impossible not to get shock/compression fronts. And what about the body of your engine? 100% frictionaless material? There will be drag - lots of drag. Basicly, you are pushing a false claim because at no time do you have the guts to trying running a model of your engine at any speed above ZERO (0) KM/H. When do we see some real tests being done? Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp I actually don't have to run my engine at high speeds. There is plenty of data from Navajo and the Bomark ramjet engines. There is of course friction and drag losses. That is the reason why I would switch to a rocket mode of operation around mach 6. The big deal is that I can run a ramjet at zero velocity without oxidizer injection. Zoltan >... >The big deal is that I can run a ramjet at zero velocity without >oxidizer injection. One can't help but note, however, that zero velocity is of limited practical value. /kenw Ken Wallewein K&M Systems Integration Phone (403)274-7848 Fax (403)275-4535 kenw@kmsi.net www.kmsi.net >>... >>The big deal is that I can run a ramjet at zero velocity without >>oxidizer injection. > > One can't help but note, however, that zero velocity is of limited > practical value. It's really handy if you want to hover, and the engine is light. Zoltan> The big deal is that I can run a ramjet at zero velocity without Zoltan> oxidizer injection. Ken> One can't help but note, however, that zero velocity is of limited Ken> practical value. Ian> It's really handy if you want to hover, and the engine is light. If the static thrust is high enough, you might be able to launch with no additional booster. That saves a bunch of complexity. One of the troubles with ramjet-boost configurations is that once you have the high-thrust booster to get the ramjet to flight speed, you are left with the tradeoff of running the ramjet, briefly, to mach 6, or just making that booster larger, and dumping the ramjet entirely. A ramjet that could take off from a dead stop could be the first stage of a TSTO. But of course, there is the problem that the first stage design is usually driven by thrust and not by ISP. > Zoltan> The big deal is that I can run a ramjet at zero velocity > without [quoted text clipped - 15 lines] > of a TSTO. But of course, there is the problem that the first stage > design is usually driven by thrust and not by ISP. But. Aerodynamic modelling of supersonic flows is not trivial. It requires lots and lots of supercomputer time, or lots and lots of testing, preferrably both. Pointing at an object on a static test stand giving a certain amount of thrust, and saying that it will continue to do so at multiple mach numbers, beyond the current state of the art requires fairly strong justification. If it hasn't even been operated at 100km/h, nevermind 1000m/s and no extensive computer simulation has been done then the claim stretches credulity to breaking point. Ian> But. Oh yeah, you're right. Zoltan's flamethrower is a really cool home hack, but he doesn't appear committed to converting it into a real first stage. Ramjets as first stages are just dumb. First, there is the air breather's burden. But lately I've been thinking about another aspect. In order to combine the incoming oxygen with the fuel you have carried, you will have to match their speeds. Unless you are building a rocket and not a ramjet, that means accelerating the incoming oxygen to vehicle speed. So what's the difference between accelerating it while in flight versus accelerating it in a tank? A: In flight, you don't have to carry the tank, nor lift off with it fully loaded. You do, however, have to accelerate 4 times as much nitrogen. In some sense, the Isp of an airbreather looks good at low speeds because it's just postponing the acceleration of most of the oxidizer, to a point later on in the flight when getting energy is less efficient. In reply to "A ramjet that could take off from a dead stop could be the first stage of a TSTO. But of course, there is the problem that the first stage design is usually driven by thrust and not by ISP. " I was just wondering how an air launch a'la Spaceship One/White Knight might change this scenario since less rocket boost would be required to get the ramjet up to speed. The ramjet first stage could be recoverable in a TSTO configuration. Seems doable, but is it worth it? Thoughts? Steve Mickler > Zoltan> The big deal is that I can run a ramjet at zero velocity > without oxidizer injection. > Ken> One can't help but note, however, that zero velocity is of limited > Ken> practical value. > Ian> It's really handy if you want to hover, and the engine is light. > [quoted text clipped - 8 lines] > of a TSTO. But of course, there is the problem that the first stage > design is usually driven by thrust and not by ISP. But. Aerodynamic modelling of supersonic flows is not trivial. It requires lots and lots of supercomputer time, or lots and lots of testing, preferrably both. Pointing at an object on a static test stand giving a certain amount of thrust, and saying that it will continue to do so at multiple mach numbers, beyond the current state of the art requires fairly strong justification. If it hasn't even been operated at 100km/h, nevermind 1000m/s and no extensive computer simulation has been done then the claim stretches credulity to breaking point. And that's not even going into the whole issue of mass ratio of existing stages to get to 2Km/s, which isn't really bad. Even with adding an extra 200m/s or so of fuel to support navigating back to base (1Km/s maybe with the top stage off) and VTOL isn't horribly heavy. (Reposted, as my first attempt does not seem to have made it) > I actually don't have to run my engine at high speeds. There is plenty > of data from Navajo and the Bomark ramjet engines. There is of course > friction and drag losses. That is the reason why I would switch to a > rocket mode of operation around mach 6. Yes, there is plenty of data. How have you analysed this? What studies of hypersonic aerodynamics have you done? How have you proved that it will run at high speeds? Hundreds of hours of analysis on paper, computer simulation, ... The navaho and bomark ramjets had an Isp of 1800 at mach 3. The fastest flight achieved by navaho was around mach 6. > The navaho and bomark ramjets had an Isp of 1800 at mach 3. > The fastest flight achieved by navaho was around mach 6. Do you have a reference for this? That would be extraordinary if true. Jim Davis "zoltan" <zoltanccc@aol.com> : > The navaho and bomark ramjets had an Isp of 1800 at mach 3. The fastest > flight achieved by navaho was around mach 6. Have you got an URL pointing to such? And by the way what was the thrust to drag ratio? If it is near 1::1 then you spend alot of time fighting drag while trying to get up to speed. Earl Colby Pottinger SignatureI make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos, SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to the time? http://webhome.idirect.com/~earlcp > The reason why we cannot use jet engines is because they are heavy And they need *air*, which you don't have for the last and most important part of the flight profile. Even a magical jet engine, that you claim to have *without* flight testing is still not going to help much. Put that engine on a RC plane and see how fast it goes. Greg > The Powers are just HUGE. One SSME, assuming 100% energy conversion to > kinetic energy of the exhaust is about 5GW . Thats 15 GW for the space > shuttle. In practice you will need a lot more than this. At 1 GW per nuclear reactor, 15 nuclear reactors. Expensive, but doable. The French manage to generate nuclear electrity at 3 eurocents/kWh. That would be about $0.036 USD/kWh. Wouldn't the fact that the vehicle weighs less (because you need less fuel) mean you need less power to move it up the gravity well than Shuttle? > This is Massive. Producting that kinda power in microwaves has only been > done on paper and the reality is that its unlikely to scale up as nicely as > you mite like. A prototype does not need to be as big as the Shuttle. If you need more power, just use a bunch of microwave generators instead of just one. The microwave generator is going to be fixed in the ground, size and weight don't matter. Just cost. > Bottom line. Chemical rockets are not as bad as you mite think. Yes they are bad. They may be the best we got, but they still suck. [...] >> Bottom line. Chemical rockets are not as bad as you mite think. > > Yes they are bad. They may be the best we got, but they still suck. Yeah, they do. Someone should hurry up and invent antigravity, quick. I had a lot of hopes on the Woodward Effect --- this is the Mach's Principle based theory that seems to predict that you can vary something's mass by changing its energy density quickly --- but I haven't heard anything from him for some time. Pity, because Woodward is actually a real scientist, with, like, papers and everything. I know that someone discovered a flaw in his experiment, and he was redesigning it, but I suspect the whole theory didn't pan out. The least weird-science way of cheaply getting to orbit seems to be one of the space elevator variants. Alas, while they seem to be considerably cheaper and easier to build than originally expected, I'm still going to be lucky to see one in my lifetime. - -- +- David Given --McQ-+ "You cannot truly appreciate _Atlas Shrugged_ | dg@cowlark.com | until you have read it in the original Klingon." | (dg@tao-group.com) | --- Sea Wasp on r.a.sf.w +- www.cowlark.com --+ |
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